src/sqlite3.h
author Dirk Zimmermann <dz@pep.security>
Thu, 11 Apr 2019 10:46:46 +0200
branchIOS-1482
changeset 3505 3fe4b41696d3
parent 3192 8797e99f7ab2
permissions -rw-r--r--
IOS-1482 close branch
     1 /*
     2 ** 2001-09-15
     3 **
     4 ** The author disclaims copyright to this source code.  In place of
     5 ** a legal notice, here is a blessing:
     6 **
     7 **    May you do good and not evil.
     8 **    May you find forgiveness for yourself and forgive others.
     9 **    May you share freely, never taking more than you give.
    10 **
    11 *************************************************************************
    12 ** This header file defines the interface that the SQLite library
    13 ** presents to client programs.  If a C-function, structure, datatype,
    14 ** or constant definition does not appear in this file, then it is
    15 ** not a published API of SQLite, is subject to change without
    16 ** notice, and should not be referenced by programs that use SQLite.
    17 **
    18 ** Some of the definitions that are in this file are marked as
    19 ** "experimental".  Experimental interfaces are normally new
    20 ** features recently added to SQLite.  We do not anticipate changes
    21 ** to experimental interfaces but reserve the right to make minor changes
    22 ** if experience from use "in the wild" suggest such changes are prudent.
    23 **
    24 ** The official C-language API documentation for SQLite is derived
    25 ** from comments in this file.  This file is the authoritative source
    26 ** on how SQLite interfaces are supposed to operate.
    27 **
    28 ** The name of this file under configuration management is "sqlite.h.in".
    29 ** The makefile makes some minor changes to this file (such as inserting
    30 ** the version number) and changes its name to "sqlite3.h" as
    31 ** part of the build process.
    32 */
    33 #ifndef SQLITE3_H
    34 #define SQLITE3_H
    35 #include <stdarg.h>     /* Needed for the definition of va_list */
    36 
    37 /*
    38 ** Make sure we can call this stuff from C++.
    39 */
    40 #ifdef __cplusplus
    41 extern "C" {
    42 #endif
    43 
    44 
    45 /*
    46 ** Provide the ability to override linkage features of the interface.
    47 */
    48 #ifndef SQLITE_EXTERN
    49 # define SQLITE_EXTERN extern
    50 #endif
    51 #ifndef SQLITE_API
    52 # define SQLITE_API
    53 #endif
    54 #ifndef SQLITE_CDECL
    55 # define SQLITE_CDECL
    56 #endif
    57 #ifndef SQLITE_APICALL
    58 # define SQLITE_APICALL
    59 #endif
    60 #ifndef SQLITE_STDCALL
    61 # define SQLITE_STDCALL SQLITE_APICALL
    62 #endif
    63 #ifndef SQLITE_CALLBACK
    64 # define SQLITE_CALLBACK
    65 #endif
    66 #ifndef SQLITE_SYSAPI
    67 # define SQLITE_SYSAPI
    68 #endif
    69 
    70 /*
    71 ** These no-op macros are used in front of interfaces to mark those
    72 ** interfaces as either deprecated or experimental.  New applications
    73 ** should not use deprecated interfaces - they are supported for backwards
    74 ** compatibility only.  Application writers should be aware that
    75 ** experimental interfaces are subject to change in point releases.
    76 **
    77 ** These macros used to resolve to various kinds of compiler magic that
    78 ** would generate warning messages when they were used.  But that
    79 ** compiler magic ended up generating such a flurry of bug reports
    80 ** that we have taken it all out and gone back to using simple
    81 ** noop macros.
    82 */
    83 #define SQLITE_DEPRECATED
    84 #define SQLITE_EXPERIMENTAL
    85 
    86 /*
    87 ** Ensure these symbols were not defined by some previous header file.
    88 */
    89 #ifdef SQLITE_VERSION
    90 # undef SQLITE_VERSION
    91 #endif
    92 #ifdef SQLITE_VERSION_NUMBER
    93 # undef SQLITE_VERSION_NUMBER
    94 #endif
    95 
    96 /*
    97 ** CAPI3REF: Compile-Time Library Version Numbers
    98 **
    99 ** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header
   100 ** evaluates to a string literal that is the SQLite version in the
   101 ** format "X.Y.Z" where X is the major version number (always 3 for
   102 ** SQLite3) and Y is the minor version number and Z is the release number.)^
   103 ** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer
   104 ** with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z are the same
   105 ** numbers used in [SQLITE_VERSION].)^
   106 ** The SQLITE_VERSION_NUMBER for any given release of SQLite will also
   107 ** be larger than the release from which it is derived.  Either Y will
   108 ** be held constant and Z will be incremented or else Y will be incremented
   109 ** and Z will be reset to zero.
   110 **
   111 ** Since [version 3.6.18] ([dateof:3.6.18]), 
   112 ** SQLite source code has been stored in the
   113 ** <a href="http://www.fossil-scm.org/">Fossil configuration management
   114 ** system</a>.  ^The SQLITE_SOURCE_ID macro evaluates to
   115 ** a string which identifies a particular check-in of SQLite
   116 ** within its configuration management system.  ^The SQLITE_SOURCE_ID
   117 ** string contains the date and time of the check-in (UTC) and a SHA1
   118 ** or SHA3-256 hash of the entire source tree.  If the source code has
   119 ** been edited in any way since it was last checked in, then the last
   120 ** four hexadecimal digits of the hash may be modified.
   121 **
   122 ** See also: [sqlite3_libversion()],
   123 ** [sqlite3_libversion_number()], [sqlite3_sourceid()],
   124 ** [sqlite_version()] and [sqlite_source_id()].
   125 */
   126 #define SQLITE_VERSION        "3.26.0"
   127 #define SQLITE_VERSION_NUMBER 3026000
   128 #define SQLITE_SOURCE_ID      "2018-12-01 12:34:55 bf8c1b2b7a5960c282e543b9c293686dccff272512d08865f4600fb58238b4f9"
   129 
   130 /*
   131 ** CAPI3REF: Run-Time Library Version Numbers
   132 ** KEYWORDS: sqlite3_version sqlite3_sourceid
   133 **
   134 ** These interfaces provide the same information as the [SQLITE_VERSION],
   135 ** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
   136 ** but are associated with the library instead of the header file.  ^(Cautious
   137 ** programmers might include assert() statements in their application to
   138 ** verify that values returned by these interfaces match the macros in
   139 ** the header, and thus ensure that the application is
   140 ** compiled with matching library and header files.
   141 **
   142 ** <blockquote><pre>
   143 ** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
   144 ** assert( strncmp(sqlite3_sourceid(),SQLITE_SOURCE_ID,80)==0 );
   145 ** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
   146 ** </pre></blockquote>)^
   147 **
   148 ** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
   149 ** macro.  ^The sqlite3_libversion() function returns a pointer to the
   150 ** to the sqlite3_version[] string constant.  The sqlite3_libversion()
   151 ** function is provided for use in DLLs since DLL users usually do not have
   152 ** direct access to string constants within the DLL.  ^The
   153 ** sqlite3_libversion_number() function returns an integer equal to
   154 ** [SQLITE_VERSION_NUMBER].  ^(The sqlite3_sourceid() function returns 
   155 ** a pointer to a string constant whose value is the same as the 
   156 ** [SQLITE_SOURCE_ID] C preprocessor macro.  Except if SQLite is built
   157 ** using an edited copy of [the amalgamation], then the last four characters
   158 ** of the hash might be different from [SQLITE_SOURCE_ID].)^
   159 **
   160 ** See also: [sqlite_version()] and [sqlite_source_id()].
   161 */
   162 SQLITE_API SQLITE_EXTERN const char sqlite3_version[];
   163 SQLITE_API const char *sqlite3_libversion(void);
   164 SQLITE_API const char *sqlite3_sourceid(void);
   165 SQLITE_API int sqlite3_libversion_number(void);
   166 
   167 /*
   168 ** CAPI3REF: Run-Time Library Compilation Options Diagnostics
   169 **
   170 ** ^The sqlite3_compileoption_used() function returns 0 or 1 
   171 ** indicating whether the specified option was defined at 
   172 ** compile time.  ^The SQLITE_ prefix may be omitted from the 
   173 ** option name passed to sqlite3_compileoption_used().  
   174 **
   175 ** ^The sqlite3_compileoption_get() function allows iterating
   176 ** over the list of options that were defined at compile time by
   177 ** returning the N-th compile time option string.  ^If N is out of range,
   178 ** sqlite3_compileoption_get() returns a NULL pointer.  ^The SQLITE_ 
   179 ** prefix is omitted from any strings returned by 
   180 ** sqlite3_compileoption_get().
   181 **
   182 ** ^Support for the diagnostic functions sqlite3_compileoption_used()
   183 ** and sqlite3_compileoption_get() may be omitted by specifying the 
   184 ** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
   185 **
   186 ** See also: SQL functions [sqlite_compileoption_used()] and
   187 ** [sqlite_compileoption_get()] and the [compile_options pragma].
   188 */
   189 #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
   190 SQLITE_API int sqlite3_compileoption_used(const char *zOptName);
   191 SQLITE_API const char *sqlite3_compileoption_get(int N);
   192 #endif
   193 
   194 /*
   195 ** CAPI3REF: Test To See If The Library Is Threadsafe
   196 **
   197 ** ^The sqlite3_threadsafe() function returns zero if and only if
   198 ** SQLite was compiled with mutexing code omitted due to the
   199 ** [SQLITE_THREADSAFE] compile-time option being set to 0.
   200 **
   201 ** SQLite can be compiled with or without mutexes.  When
   202 ** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes
   203 ** are enabled and SQLite is threadsafe.  When the
   204 ** [SQLITE_THREADSAFE] macro is 0, 
   205 ** the mutexes are omitted.  Without the mutexes, it is not safe
   206 ** to use SQLite concurrently from more than one thread.
   207 **
   208 ** Enabling mutexes incurs a measurable performance penalty.
   209 ** So if speed is of utmost importance, it makes sense to disable
   210 ** the mutexes.  But for maximum safety, mutexes should be enabled.
   211 ** ^The default behavior is for mutexes to be enabled.
   212 **
   213 ** This interface can be used by an application to make sure that the
   214 ** version of SQLite that it is linking against was compiled with
   215 ** the desired setting of the [SQLITE_THREADSAFE] macro.
   216 **
   217 ** This interface only reports on the compile-time mutex setting
   218 ** of the [SQLITE_THREADSAFE] flag.  If SQLite is compiled with
   219 ** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but
   220 ** can be fully or partially disabled using a call to [sqlite3_config()]
   221 ** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],
   222 ** or [SQLITE_CONFIG_SERIALIZED].  ^(The return value of the
   223 ** sqlite3_threadsafe() function shows only the compile-time setting of
   224 ** thread safety, not any run-time changes to that setting made by
   225 ** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()
   226 ** is unchanged by calls to sqlite3_config().)^
   227 **
   228 ** See the [threading mode] documentation for additional information.
   229 */
   230 SQLITE_API int sqlite3_threadsafe(void);
   231 
   232 /*
   233 ** CAPI3REF: Database Connection Handle
   234 ** KEYWORDS: {database connection} {database connections}
   235 **
   236 ** Each open SQLite database is represented by a pointer to an instance of
   237 ** the opaque structure named "sqlite3".  It is useful to think of an sqlite3
   238 ** pointer as an object.  The [sqlite3_open()], [sqlite3_open16()], and
   239 ** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
   240 ** and [sqlite3_close_v2()] are its destructors.  There are many other
   241 ** interfaces (such as
   242 ** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
   243 ** [sqlite3_busy_timeout()] to name but three) that are methods on an
   244 ** sqlite3 object.
   245 */
   246 typedef struct sqlite3 sqlite3;
   247 
   248 /*
   249 ** CAPI3REF: 64-Bit Integer Types
   250 ** KEYWORDS: sqlite_int64 sqlite_uint64
   251 **
   252 ** Because there is no cross-platform way to specify 64-bit integer types
   253 ** SQLite includes typedefs for 64-bit signed and unsigned integers.
   254 **
   255 ** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
   256 ** The sqlite_int64 and sqlite_uint64 types are supported for backwards
   257 ** compatibility only.
   258 **
   259 ** ^The sqlite3_int64 and sqlite_int64 types can store integer values
   260 ** between -9223372036854775808 and +9223372036854775807 inclusive.  ^The
   261 ** sqlite3_uint64 and sqlite_uint64 types can store integer values 
   262 ** between 0 and +18446744073709551615 inclusive.
   263 */
   264 #ifdef SQLITE_INT64_TYPE
   265   typedef SQLITE_INT64_TYPE sqlite_int64;
   266 # ifdef SQLITE_UINT64_TYPE
   267     typedef SQLITE_UINT64_TYPE sqlite_uint64;
   268 # else  
   269     typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
   270 # endif
   271 #elif defined(_MSC_VER) || defined(__BORLANDC__)
   272   typedef __int64 sqlite_int64;
   273   typedef unsigned __int64 sqlite_uint64;
   274 #else
   275   typedef long long int sqlite_int64;
   276   typedef unsigned long long int sqlite_uint64;
   277 #endif
   278 typedef sqlite_int64 sqlite3_int64;
   279 typedef sqlite_uint64 sqlite3_uint64;
   280 
   281 /*
   282 ** If compiling for a processor that lacks floating point support,
   283 ** substitute integer for floating-point.
   284 */
   285 #ifdef SQLITE_OMIT_FLOATING_POINT
   286 # define double sqlite3_int64
   287 #endif
   288 
   289 /*
   290 ** CAPI3REF: Closing A Database Connection
   291 ** DESTRUCTOR: sqlite3
   292 **
   293 ** ^The sqlite3_close() and sqlite3_close_v2() routines are destructors
   294 ** for the [sqlite3] object.
   295 ** ^Calls to sqlite3_close() and sqlite3_close_v2() return [SQLITE_OK] if
   296 ** the [sqlite3] object is successfully destroyed and all associated
   297 ** resources are deallocated.
   298 **
   299 ** ^If the database connection is associated with unfinalized prepared
   300 ** statements or unfinished sqlite3_backup objects then sqlite3_close()
   301 ** will leave the database connection open and return [SQLITE_BUSY].
   302 ** ^If sqlite3_close_v2() is called with unfinalized prepared statements
   303 ** and/or unfinished sqlite3_backups, then the database connection becomes
   304 ** an unusable "zombie" which will automatically be deallocated when the
   305 ** last prepared statement is finalized or the last sqlite3_backup is
   306 ** finished.  The sqlite3_close_v2() interface is intended for use with
   307 ** host languages that are garbage collected, and where the order in which
   308 ** destructors are called is arbitrary.
   309 **
   310 ** Applications should [sqlite3_finalize | finalize] all [prepared statements],
   311 ** [sqlite3_blob_close | close] all [BLOB handles], and 
   312 ** [sqlite3_backup_finish | finish] all [sqlite3_backup] objects associated
   313 ** with the [sqlite3] object prior to attempting to close the object.  ^If
   314 ** sqlite3_close_v2() is called on a [database connection] that still has
   315 ** outstanding [prepared statements], [BLOB handles], and/or
   316 ** [sqlite3_backup] objects then it returns [SQLITE_OK] and the deallocation
   317 ** of resources is deferred until all [prepared statements], [BLOB handles],
   318 ** and [sqlite3_backup] objects are also destroyed.
   319 **
   320 ** ^If an [sqlite3] object is destroyed while a transaction is open,
   321 ** the transaction is automatically rolled back.
   322 **
   323 ** The C parameter to [sqlite3_close(C)] and [sqlite3_close_v2(C)]
   324 ** must be either a NULL
   325 ** pointer or an [sqlite3] object pointer obtained
   326 ** from [sqlite3_open()], [sqlite3_open16()], or
   327 ** [sqlite3_open_v2()], and not previously closed.
   328 ** ^Calling sqlite3_close() or sqlite3_close_v2() with a NULL pointer
   329 ** argument is a harmless no-op.
   330 */
   331 SQLITE_API int sqlite3_close(sqlite3*);
   332 SQLITE_API int sqlite3_close_v2(sqlite3*);
   333 
   334 /*
   335 ** The type for a callback function.
   336 ** This is legacy and deprecated.  It is included for historical
   337 ** compatibility and is not documented.
   338 */
   339 typedef int (*sqlite3_callback)(void*,int,char**, char**);
   340 
   341 /*
   342 ** CAPI3REF: One-Step Query Execution Interface
   343 ** METHOD: sqlite3
   344 **
   345 ** The sqlite3_exec() interface is a convenience wrapper around
   346 ** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],
   347 ** that allows an application to run multiple statements of SQL
   348 ** without having to use a lot of C code. 
   349 **
   350 ** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
   351 ** semicolon-separate SQL statements passed into its 2nd argument,
   352 ** in the context of the [database connection] passed in as its 1st
   353 ** argument.  ^If the callback function of the 3rd argument to
   354 ** sqlite3_exec() is not NULL, then it is invoked for each result row
   355 ** coming out of the evaluated SQL statements.  ^The 4th argument to
   356 ** sqlite3_exec() is relayed through to the 1st argument of each
   357 ** callback invocation.  ^If the callback pointer to sqlite3_exec()
   358 ** is NULL, then no callback is ever invoked and result rows are
   359 ** ignored.
   360 **
   361 ** ^If an error occurs while evaluating the SQL statements passed into
   362 ** sqlite3_exec(), then execution of the current statement stops and
   363 ** subsequent statements are skipped.  ^If the 5th parameter to sqlite3_exec()
   364 ** is not NULL then any error message is written into memory obtained
   365 ** from [sqlite3_malloc()] and passed back through the 5th parameter.
   366 ** To avoid memory leaks, the application should invoke [sqlite3_free()]
   367 ** on error message strings returned through the 5th parameter of
   368 ** sqlite3_exec() after the error message string is no longer needed.
   369 ** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
   370 ** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
   371 ** NULL before returning.
   372 **
   373 ** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()
   374 ** routine returns SQLITE_ABORT without invoking the callback again and
   375 ** without running any subsequent SQL statements.
   376 **
   377 ** ^The 2nd argument to the sqlite3_exec() callback function is the
   378 ** number of columns in the result.  ^The 3rd argument to the sqlite3_exec()
   379 ** callback is an array of pointers to strings obtained as if from
   380 ** [sqlite3_column_text()], one for each column.  ^If an element of a
   381 ** result row is NULL then the corresponding string pointer for the
   382 ** sqlite3_exec() callback is a NULL pointer.  ^The 4th argument to the
   383 ** sqlite3_exec() callback is an array of pointers to strings where each
   384 ** entry represents the name of corresponding result column as obtained
   385 ** from [sqlite3_column_name()].
   386 **
   387 ** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer
   388 ** to an empty string, or a pointer that contains only whitespace and/or 
   389 ** SQL comments, then no SQL statements are evaluated and the database
   390 ** is not changed.
   391 **
   392 ** Restrictions:
   393 **
   394 ** <ul>
   395 ** <li> The application must ensure that the 1st parameter to sqlite3_exec()
   396 **      is a valid and open [database connection].
   397 ** <li> The application must not close the [database connection] specified by
   398 **      the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
   399 ** <li> The application must not modify the SQL statement text passed into
   400 **      the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.
   401 ** </ul>
   402 */
   403 SQLITE_API int sqlite3_exec(
   404   sqlite3*,                                  /* An open database */
   405   const char *sql,                           /* SQL to be evaluated */
   406   int (*callback)(void*,int,char**,char**),  /* Callback function */
   407   void *,                                    /* 1st argument to callback */
   408   char **errmsg                              /* Error msg written here */
   409 );
   410 
   411 /*
   412 ** CAPI3REF: Result Codes
   413 ** KEYWORDS: {result code definitions}
   414 **
   415 ** Many SQLite functions return an integer result code from the set shown
   416 ** here in order to indicate success or failure.
   417 **
   418 ** New error codes may be added in future versions of SQLite.
   419 **
   420 ** See also: [extended result code definitions]
   421 */
   422 #define SQLITE_OK           0   /* Successful result */
   423 /* beginning-of-error-codes */
   424 #define SQLITE_ERROR        1   /* Generic error */
   425 #define SQLITE_INTERNAL     2   /* Internal logic error in SQLite */
   426 #define SQLITE_PERM         3   /* Access permission denied */
   427 #define SQLITE_ABORT        4   /* Callback routine requested an abort */
   428 #define SQLITE_BUSY         5   /* The database file is locked */
   429 #define SQLITE_LOCKED       6   /* A table in the database is locked */
   430 #define SQLITE_NOMEM        7   /* A malloc() failed */
   431 #define SQLITE_READONLY     8   /* Attempt to write a readonly database */
   432 #define SQLITE_INTERRUPT    9   /* Operation terminated by sqlite3_interrupt()*/
   433 #define SQLITE_IOERR       10   /* Some kind of disk I/O error occurred */
   434 #define SQLITE_CORRUPT     11   /* The database disk image is malformed */
   435 #define SQLITE_NOTFOUND    12   /* Unknown opcode in sqlite3_file_control() */
   436 #define SQLITE_FULL        13   /* Insertion failed because database is full */
   437 #define SQLITE_CANTOPEN    14   /* Unable to open the database file */
   438 #define SQLITE_PROTOCOL    15   /* Database lock protocol error */
   439 #define SQLITE_EMPTY       16   /* Internal use only */
   440 #define SQLITE_SCHEMA      17   /* The database schema changed */
   441 #define SQLITE_TOOBIG      18   /* String or BLOB exceeds size limit */
   442 #define SQLITE_CONSTRAINT  19   /* Abort due to constraint violation */
   443 #define SQLITE_MISMATCH    20   /* Data type mismatch */
   444 #define SQLITE_MISUSE      21   /* Library used incorrectly */
   445 #define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
   446 #define SQLITE_AUTH        23   /* Authorization denied */
   447 #define SQLITE_FORMAT      24   /* Not used */
   448 #define SQLITE_RANGE       25   /* 2nd parameter to sqlite3_bind out of range */
   449 #define SQLITE_NOTADB      26   /* File opened that is not a database file */
   450 #define SQLITE_NOTICE      27   /* Notifications from sqlite3_log() */
   451 #define SQLITE_WARNING     28   /* Warnings from sqlite3_log() */
   452 #define SQLITE_ROW         100  /* sqlite3_step() has another row ready */
   453 #define SQLITE_DONE        101  /* sqlite3_step() has finished executing */
   454 /* end-of-error-codes */
   455 
   456 /*
   457 ** CAPI3REF: Extended Result Codes
   458 ** KEYWORDS: {extended result code definitions}
   459 **
   460 ** In its default configuration, SQLite API routines return one of 30 integer
   461 ** [result codes].  However, experience has shown that many of
   462 ** these result codes are too coarse-grained.  They do not provide as
   463 ** much information about problems as programmers might like.  In an effort to
   464 ** address this, newer versions of SQLite (version 3.3.8 [dateof:3.3.8]
   465 ** and later) include
   466 ** support for additional result codes that provide more detailed information
   467 ** about errors. These [extended result codes] are enabled or disabled
   468 ** on a per database connection basis using the
   469 ** [sqlite3_extended_result_codes()] API.  Or, the extended code for
   470 ** the most recent error can be obtained using
   471 ** [sqlite3_extended_errcode()].
   472 */
   473 #define SQLITE_ERROR_MISSING_COLLSEQ   (SQLITE_ERROR | (1<<8))
   474 #define SQLITE_ERROR_RETRY             (SQLITE_ERROR | (2<<8))
   475 #define SQLITE_ERROR_SNAPSHOT          (SQLITE_ERROR | (3<<8))
   476 #define SQLITE_IOERR_READ              (SQLITE_IOERR | (1<<8))
   477 #define SQLITE_IOERR_SHORT_READ        (SQLITE_IOERR | (2<<8))
   478 #define SQLITE_IOERR_WRITE             (SQLITE_IOERR | (3<<8))
   479 #define SQLITE_IOERR_FSYNC             (SQLITE_IOERR | (4<<8))
   480 #define SQLITE_IOERR_DIR_FSYNC         (SQLITE_IOERR | (5<<8))
   481 #define SQLITE_IOERR_TRUNCATE          (SQLITE_IOERR | (6<<8))
   482 #define SQLITE_IOERR_FSTAT             (SQLITE_IOERR | (7<<8))
   483 #define SQLITE_IOERR_UNLOCK            (SQLITE_IOERR | (8<<8))
   484 #define SQLITE_IOERR_RDLOCK            (SQLITE_IOERR | (9<<8))
   485 #define SQLITE_IOERR_DELETE            (SQLITE_IOERR | (10<<8))
   486 #define SQLITE_IOERR_BLOCKED           (SQLITE_IOERR | (11<<8))
   487 #define SQLITE_IOERR_NOMEM             (SQLITE_IOERR | (12<<8))
   488 #define SQLITE_IOERR_ACCESS            (SQLITE_IOERR | (13<<8))
   489 #define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
   490 #define SQLITE_IOERR_LOCK              (SQLITE_IOERR | (15<<8))
   491 #define SQLITE_IOERR_CLOSE             (SQLITE_IOERR | (16<<8))
   492 #define SQLITE_IOERR_DIR_CLOSE         (SQLITE_IOERR | (17<<8))
   493 #define SQLITE_IOERR_SHMOPEN           (SQLITE_IOERR | (18<<8))
   494 #define SQLITE_IOERR_SHMSIZE           (SQLITE_IOERR | (19<<8))
   495 #define SQLITE_IOERR_SHMLOCK           (SQLITE_IOERR | (20<<8))
   496 #define SQLITE_IOERR_SHMMAP            (SQLITE_IOERR | (21<<8))
   497 #define SQLITE_IOERR_SEEK              (SQLITE_IOERR | (22<<8))
   498 #define SQLITE_IOERR_DELETE_NOENT      (SQLITE_IOERR | (23<<8))
   499 #define SQLITE_IOERR_MMAP              (SQLITE_IOERR | (24<<8))
   500 #define SQLITE_IOERR_GETTEMPPATH       (SQLITE_IOERR | (25<<8))
   501 #define SQLITE_IOERR_CONVPATH          (SQLITE_IOERR | (26<<8))
   502 #define SQLITE_IOERR_VNODE             (SQLITE_IOERR | (27<<8))
   503 #define SQLITE_IOERR_AUTH              (SQLITE_IOERR | (28<<8))
   504 #define SQLITE_IOERR_BEGIN_ATOMIC      (SQLITE_IOERR | (29<<8))
   505 #define SQLITE_IOERR_COMMIT_ATOMIC     (SQLITE_IOERR | (30<<8))
   506 #define SQLITE_IOERR_ROLLBACK_ATOMIC   (SQLITE_IOERR | (31<<8))
   507 #define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
   508 #define SQLITE_LOCKED_VTAB             (SQLITE_LOCKED |  (2<<8))
   509 #define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
   510 #define SQLITE_BUSY_SNAPSHOT           (SQLITE_BUSY   |  (2<<8))
   511 #define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
   512 #define SQLITE_CANTOPEN_ISDIR          (SQLITE_CANTOPEN | (2<<8))
   513 #define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
   514 #define SQLITE_CANTOPEN_CONVPATH       (SQLITE_CANTOPEN | (4<<8))
   515 #define SQLITE_CANTOPEN_DIRTYWAL       (SQLITE_CANTOPEN | (5<<8)) /* Not Used */
   516 #define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
   517 #define SQLITE_CORRUPT_SEQUENCE        (SQLITE_CORRUPT | (2<<8))
   518 #define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
   519 #define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))
   520 #define SQLITE_READONLY_ROLLBACK       (SQLITE_READONLY | (3<<8))
   521 #define SQLITE_READONLY_DBMOVED        (SQLITE_READONLY | (4<<8))
   522 #define SQLITE_READONLY_CANTINIT       (SQLITE_READONLY | (5<<8))
   523 #define SQLITE_READONLY_DIRECTORY      (SQLITE_READONLY | (6<<8))
   524 #define SQLITE_ABORT_ROLLBACK          (SQLITE_ABORT | (2<<8))
   525 #define SQLITE_CONSTRAINT_CHECK        (SQLITE_CONSTRAINT | (1<<8))
   526 #define SQLITE_CONSTRAINT_COMMITHOOK   (SQLITE_CONSTRAINT | (2<<8))
   527 #define SQLITE_CONSTRAINT_FOREIGNKEY   (SQLITE_CONSTRAINT | (3<<8))
   528 #define SQLITE_CONSTRAINT_FUNCTION     (SQLITE_CONSTRAINT | (4<<8))
   529 #define SQLITE_CONSTRAINT_NOTNULL      (SQLITE_CONSTRAINT | (5<<8))
   530 #define SQLITE_CONSTRAINT_PRIMARYKEY   (SQLITE_CONSTRAINT | (6<<8))
   531 #define SQLITE_CONSTRAINT_TRIGGER      (SQLITE_CONSTRAINT | (7<<8))
   532 #define SQLITE_CONSTRAINT_UNIQUE       (SQLITE_CONSTRAINT | (8<<8))
   533 #define SQLITE_CONSTRAINT_VTAB         (SQLITE_CONSTRAINT | (9<<8))
   534 #define SQLITE_CONSTRAINT_ROWID        (SQLITE_CONSTRAINT |(10<<8))
   535 #define SQLITE_NOTICE_RECOVER_WAL      (SQLITE_NOTICE | (1<<8))
   536 #define SQLITE_NOTICE_RECOVER_ROLLBACK (SQLITE_NOTICE | (2<<8))
   537 #define SQLITE_WARNING_AUTOINDEX       (SQLITE_WARNING | (1<<8))
   538 #define SQLITE_AUTH_USER               (SQLITE_AUTH | (1<<8))
   539 #define SQLITE_OK_LOAD_PERMANENTLY     (SQLITE_OK | (1<<8))
   540 
   541 /*
   542 ** CAPI3REF: Flags For File Open Operations
   543 **
   544 ** These bit values are intended for use in the
   545 ** 3rd parameter to the [sqlite3_open_v2()] interface and
   546 ** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
   547 */
   548 #define SQLITE_OPEN_READONLY         0x00000001  /* Ok for sqlite3_open_v2() */
   549 #define SQLITE_OPEN_READWRITE        0x00000002  /* Ok for sqlite3_open_v2() */
   550 #define SQLITE_OPEN_CREATE           0x00000004  /* Ok for sqlite3_open_v2() */
   551 #define SQLITE_OPEN_DELETEONCLOSE    0x00000008  /* VFS only */
   552 #define SQLITE_OPEN_EXCLUSIVE        0x00000010  /* VFS only */
   553 #define SQLITE_OPEN_AUTOPROXY        0x00000020  /* VFS only */
   554 #define SQLITE_OPEN_URI              0x00000040  /* Ok for sqlite3_open_v2() */
   555 #define SQLITE_OPEN_MEMORY           0x00000080  /* Ok for sqlite3_open_v2() */
   556 #define SQLITE_OPEN_MAIN_DB          0x00000100  /* VFS only */
   557 #define SQLITE_OPEN_TEMP_DB          0x00000200  /* VFS only */
   558 #define SQLITE_OPEN_TRANSIENT_DB     0x00000400  /* VFS only */
   559 #define SQLITE_OPEN_MAIN_JOURNAL     0x00000800  /* VFS only */
   560 #define SQLITE_OPEN_TEMP_JOURNAL     0x00001000  /* VFS only */
   561 #define SQLITE_OPEN_SUBJOURNAL       0x00002000  /* VFS only */
   562 #define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */
   563 #define SQLITE_OPEN_NOMUTEX          0x00008000  /* Ok for sqlite3_open_v2() */
   564 #define SQLITE_OPEN_FULLMUTEX        0x00010000  /* Ok for sqlite3_open_v2() */
   565 #define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
   566 #define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */
   567 #define SQLITE_OPEN_WAL              0x00080000  /* VFS only */
   568 
   569 /* Reserved:                         0x00F00000 */
   570 
   571 /*
   572 ** CAPI3REF: Device Characteristics
   573 **
   574 ** The xDeviceCharacteristics method of the [sqlite3_io_methods]
   575 ** object returns an integer which is a vector of these
   576 ** bit values expressing I/O characteristics of the mass storage
   577 ** device that holds the file that the [sqlite3_io_methods]
   578 ** refers to.
   579 **
   580 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
   581 ** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
   582 ** mean that writes of blocks that are nnn bytes in size and
   583 ** are aligned to an address which is an integer multiple of
   584 ** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
   585 ** that when data is appended to a file, the data is appended
   586 ** first then the size of the file is extended, never the other
   587 ** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
   588 ** information is written to disk in the same order as calls
   589 ** to xWrite().  The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that
   590 ** after reboot following a crash or power loss, the only bytes in a
   591 ** file that were written at the application level might have changed
   592 ** and that adjacent bytes, even bytes within the same sector are
   593 ** guaranteed to be unchanged.  The SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
   594 ** flag indicates that a file cannot be deleted when open.  The
   595 ** SQLITE_IOCAP_IMMUTABLE flag indicates that the file is on
   596 ** read-only media and cannot be changed even by processes with
   597 ** elevated privileges.
   598 **
   599 ** The SQLITE_IOCAP_BATCH_ATOMIC property means that the underlying
   600 ** filesystem supports doing multiple write operations atomically when those
   601 ** write operations are bracketed by [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE] and
   602 ** [SQLITE_FCNTL_COMMIT_ATOMIC_WRITE].
   603 */
   604 #define SQLITE_IOCAP_ATOMIC                 0x00000001
   605 #define SQLITE_IOCAP_ATOMIC512              0x00000002
   606 #define SQLITE_IOCAP_ATOMIC1K               0x00000004
   607 #define SQLITE_IOCAP_ATOMIC2K               0x00000008
   608 #define SQLITE_IOCAP_ATOMIC4K               0x00000010
   609 #define SQLITE_IOCAP_ATOMIC8K               0x00000020
   610 #define SQLITE_IOCAP_ATOMIC16K              0x00000040
   611 #define SQLITE_IOCAP_ATOMIC32K              0x00000080
   612 #define SQLITE_IOCAP_ATOMIC64K              0x00000100
   613 #define SQLITE_IOCAP_SAFE_APPEND            0x00000200
   614 #define SQLITE_IOCAP_SEQUENTIAL             0x00000400
   615 #define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN  0x00000800
   616 #define SQLITE_IOCAP_POWERSAFE_OVERWRITE    0x00001000
   617 #define SQLITE_IOCAP_IMMUTABLE              0x00002000
   618 #define SQLITE_IOCAP_BATCH_ATOMIC           0x00004000
   619 
   620 /*
   621 ** CAPI3REF: File Locking Levels
   622 **
   623 ** SQLite uses one of these integer values as the second
   624 ** argument to calls it makes to the xLock() and xUnlock() methods
   625 ** of an [sqlite3_io_methods] object.
   626 */
   627 #define SQLITE_LOCK_NONE          0
   628 #define SQLITE_LOCK_SHARED        1
   629 #define SQLITE_LOCK_RESERVED      2
   630 #define SQLITE_LOCK_PENDING       3
   631 #define SQLITE_LOCK_EXCLUSIVE     4
   632 
   633 /*
   634 ** CAPI3REF: Synchronization Type Flags
   635 **
   636 ** When SQLite invokes the xSync() method of an
   637 ** [sqlite3_io_methods] object it uses a combination of
   638 ** these integer values as the second argument.
   639 **
   640 ** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
   641 ** sync operation only needs to flush data to mass storage.  Inode
   642 ** information need not be flushed. If the lower four bits of the flag
   643 ** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.
   644 ** If the lower four bits equal SQLITE_SYNC_FULL, that means
   645 ** to use Mac OS X style fullsync instead of fsync().
   646 **
   647 ** Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags
   648 ** with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL
   649 ** settings.  The [synchronous pragma] determines when calls to the
   650 ** xSync VFS method occur and applies uniformly across all platforms.
   651 ** The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how
   652 ** energetic or rigorous or forceful the sync operations are and
   653 ** only make a difference on Mac OSX for the default SQLite code.
   654 ** (Third-party VFS implementations might also make the distinction
   655 ** between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the
   656 ** operating systems natively supported by SQLite, only Mac OSX
   657 ** cares about the difference.)
   658 */
   659 #define SQLITE_SYNC_NORMAL        0x00002
   660 #define SQLITE_SYNC_FULL          0x00003
   661 #define SQLITE_SYNC_DATAONLY      0x00010
   662 
   663 /*
   664 ** CAPI3REF: OS Interface Open File Handle
   665 **
   666 ** An [sqlite3_file] object represents an open file in the 
   667 ** [sqlite3_vfs | OS interface layer].  Individual OS interface
   668 ** implementations will
   669 ** want to subclass this object by appending additional fields
   670 ** for their own use.  The pMethods entry is a pointer to an
   671 ** [sqlite3_io_methods] object that defines methods for performing
   672 ** I/O operations on the open file.
   673 */
   674 typedef struct sqlite3_file sqlite3_file;
   675 struct sqlite3_file {
   676   const struct sqlite3_io_methods *pMethods;  /* Methods for an open file */
   677 };
   678 
   679 /*
   680 ** CAPI3REF: OS Interface File Virtual Methods Object
   681 **
   682 ** Every file opened by the [sqlite3_vfs.xOpen] method populates an
   683 ** [sqlite3_file] object (or, more commonly, a subclass of the
   684 ** [sqlite3_file] object) with a pointer to an instance of this object.
   685 ** This object defines the methods used to perform various operations
   686 ** against the open file represented by the [sqlite3_file] object.
   687 **
   688 ** If the [sqlite3_vfs.xOpen] method sets the sqlite3_file.pMethods element 
   689 ** to a non-NULL pointer, then the sqlite3_io_methods.xClose method
   690 ** may be invoked even if the [sqlite3_vfs.xOpen] reported that it failed.  The
   691 ** only way to prevent a call to xClose following a failed [sqlite3_vfs.xOpen]
   692 ** is for the [sqlite3_vfs.xOpen] to set the sqlite3_file.pMethods element
   693 ** to NULL.
   694 **
   695 ** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
   696 ** [SQLITE_SYNC_FULL].  The first choice is the normal fsync().
   697 ** The second choice is a Mac OS X style fullsync.  The [SQLITE_SYNC_DATAONLY]
   698 ** flag may be ORed in to indicate that only the data of the file
   699 ** and not its inode needs to be synced.
   700 **
   701 ** The integer values to xLock() and xUnlock() are one of
   702 ** <ul>
   703 ** <li> [SQLITE_LOCK_NONE],
   704 ** <li> [SQLITE_LOCK_SHARED],
   705 ** <li> [SQLITE_LOCK_RESERVED],
   706 ** <li> [SQLITE_LOCK_PENDING], or
   707 ** <li> [SQLITE_LOCK_EXCLUSIVE].
   708 ** </ul>
   709 ** xLock() increases the lock. xUnlock() decreases the lock.
   710 ** The xCheckReservedLock() method checks whether any database connection,
   711 ** either in this process or in some other process, is holding a RESERVED,
   712 ** PENDING, or EXCLUSIVE lock on the file.  It returns true
   713 ** if such a lock exists and false otherwise.
   714 **
   715 ** The xFileControl() method is a generic interface that allows custom
   716 ** VFS implementations to directly control an open file using the
   717 ** [sqlite3_file_control()] interface.  The second "op" argument is an
   718 ** integer opcode.  The third argument is a generic pointer intended to
   719 ** point to a structure that may contain arguments or space in which to
   720 ** write return values.  Potential uses for xFileControl() might be
   721 ** functions to enable blocking locks with timeouts, to change the
   722 ** locking strategy (for example to use dot-file locks), to inquire
   723 ** about the status of a lock, or to break stale locks.  The SQLite
   724 ** core reserves all opcodes less than 100 for its own use.
   725 ** A [file control opcodes | list of opcodes] less than 100 is available.
   726 ** Applications that define a custom xFileControl method should use opcodes
   727 ** greater than 100 to avoid conflicts.  VFS implementations should
   728 ** return [SQLITE_NOTFOUND] for file control opcodes that they do not
   729 ** recognize.
   730 **
   731 ** The xSectorSize() method returns the sector size of the
   732 ** device that underlies the file.  The sector size is the
   733 ** minimum write that can be performed without disturbing
   734 ** other bytes in the file.  The xDeviceCharacteristics()
   735 ** method returns a bit vector describing behaviors of the
   736 ** underlying device:
   737 **
   738 ** <ul>
   739 ** <li> [SQLITE_IOCAP_ATOMIC]
   740 ** <li> [SQLITE_IOCAP_ATOMIC512]
   741 ** <li> [SQLITE_IOCAP_ATOMIC1K]
   742 ** <li> [SQLITE_IOCAP_ATOMIC2K]
   743 ** <li> [SQLITE_IOCAP_ATOMIC4K]
   744 ** <li> [SQLITE_IOCAP_ATOMIC8K]
   745 ** <li> [SQLITE_IOCAP_ATOMIC16K]
   746 ** <li> [SQLITE_IOCAP_ATOMIC32K]
   747 ** <li> [SQLITE_IOCAP_ATOMIC64K]
   748 ** <li> [SQLITE_IOCAP_SAFE_APPEND]
   749 ** <li> [SQLITE_IOCAP_SEQUENTIAL]
   750 ** <li> [SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN]
   751 ** <li> [SQLITE_IOCAP_POWERSAFE_OVERWRITE]
   752 ** <li> [SQLITE_IOCAP_IMMUTABLE]
   753 ** <li> [SQLITE_IOCAP_BATCH_ATOMIC]
   754 ** </ul>
   755 **
   756 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
   757 ** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
   758 ** mean that writes of blocks that are nnn bytes in size and
   759 ** are aligned to an address which is an integer multiple of
   760 ** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
   761 ** that when data is appended to a file, the data is appended
   762 ** first then the size of the file is extended, never the other
   763 ** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
   764 ** information is written to disk in the same order as calls
   765 ** to xWrite().
   766 **
   767 ** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
   768 ** in the unread portions of the buffer with zeros.  A VFS that
   769 ** fails to zero-fill short reads might seem to work.  However,
   770 ** failure to zero-fill short reads will eventually lead to
   771 ** database corruption.
   772 */
   773 typedef struct sqlite3_io_methods sqlite3_io_methods;
   774 struct sqlite3_io_methods {
   775   int iVersion;
   776   int (*xClose)(sqlite3_file*);
   777   int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
   778   int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
   779   int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
   780   int (*xSync)(sqlite3_file*, int flags);
   781   int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
   782   int (*xLock)(sqlite3_file*, int);
   783   int (*xUnlock)(sqlite3_file*, int);
   784   int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
   785   int (*xFileControl)(sqlite3_file*, int op, void *pArg);
   786   int (*xSectorSize)(sqlite3_file*);
   787   int (*xDeviceCharacteristics)(sqlite3_file*);
   788   /* Methods above are valid for version 1 */
   789   int (*xShmMap)(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
   790   int (*xShmLock)(sqlite3_file*, int offset, int n, int flags);
   791   void (*xShmBarrier)(sqlite3_file*);
   792   int (*xShmUnmap)(sqlite3_file*, int deleteFlag);
   793   /* Methods above are valid for version 2 */
   794   int (*xFetch)(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
   795   int (*xUnfetch)(sqlite3_file*, sqlite3_int64 iOfst, void *p);
   796   /* Methods above are valid for version 3 */
   797   /* Additional methods may be added in future releases */
   798 };
   799 
   800 /*
   801 ** CAPI3REF: Standard File Control Opcodes
   802 ** KEYWORDS: {file control opcodes} {file control opcode}
   803 **
   804 ** These integer constants are opcodes for the xFileControl method
   805 ** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
   806 ** interface.
   807 **
   808 ** <ul>
   809 ** <li>[[SQLITE_FCNTL_LOCKSTATE]]
   810 ** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging.  This
   811 ** opcode causes the xFileControl method to write the current state of
   812 ** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
   813 ** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
   814 ** into an integer that the pArg argument points to. This capability
   815 ** is used during testing and is only available when the SQLITE_TEST
   816 ** compile-time option is used.
   817 **
   818 ** <li>[[SQLITE_FCNTL_SIZE_HINT]]
   819 ** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
   820 ** layer a hint of how large the database file will grow to be during the
   821 ** current transaction.  This hint is not guaranteed to be accurate but it
   822 ** is often close.  The underlying VFS might choose to preallocate database
   823 ** file space based on this hint in order to help writes to the database
   824 ** file run faster.
   825 **
   826 ** <li>[[SQLITE_FCNTL_CHUNK_SIZE]]
   827 ** The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS
   828 ** extends and truncates the database file in chunks of a size specified
   829 ** by the user. The fourth argument to [sqlite3_file_control()] should 
   830 ** point to an integer (type int) containing the new chunk-size to use
   831 ** for the nominated database. Allocating database file space in large
   832 ** chunks (say 1MB at a time), may reduce file-system fragmentation and
   833 ** improve performance on some systems.
   834 **
   835 ** <li>[[SQLITE_FCNTL_FILE_POINTER]]
   836 ** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
   837 ** to the [sqlite3_file] object associated with a particular database
   838 ** connection.  See also [SQLITE_FCNTL_JOURNAL_POINTER].
   839 **
   840 ** <li>[[SQLITE_FCNTL_JOURNAL_POINTER]]
   841 ** The [SQLITE_FCNTL_JOURNAL_POINTER] opcode is used to obtain a pointer
   842 ** to the [sqlite3_file] object associated with the journal file (either
   843 ** the [rollback journal] or the [write-ahead log]) for a particular database
   844 ** connection.  See also [SQLITE_FCNTL_FILE_POINTER].
   845 **
   846 ** <li>[[SQLITE_FCNTL_SYNC_OMITTED]]
   847 ** No longer in use.
   848 **
   849 ** <li>[[SQLITE_FCNTL_SYNC]]
   850 ** The [SQLITE_FCNTL_SYNC] opcode is generated internally by SQLite and
   851 ** sent to the VFS immediately before the xSync method is invoked on a
   852 ** database file descriptor. Or, if the xSync method is not invoked 
   853 ** because the user has configured SQLite with 
   854 ** [PRAGMA synchronous | PRAGMA synchronous=OFF] it is invoked in place 
   855 ** of the xSync method. In most cases, the pointer argument passed with
   856 ** this file-control is NULL. However, if the database file is being synced
   857 ** as part of a multi-database commit, the argument points to a nul-terminated
   858 ** string containing the transactions master-journal file name. VFSes that 
   859 ** do not need this signal should silently ignore this opcode. Applications 
   860 ** should not call [sqlite3_file_control()] with this opcode as doing so may 
   861 ** disrupt the operation of the specialized VFSes that do require it.  
   862 **
   863 ** <li>[[SQLITE_FCNTL_COMMIT_PHASETWO]]
   864 ** The [SQLITE_FCNTL_COMMIT_PHASETWO] opcode is generated internally by SQLite
   865 ** and sent to the VFS after a transaction has been committed immediately
   866 ** but before the database is unlocked. VFSes that do not need this signal
   867 ** should silently ignore this opcode. Applications should not call
   868 ** [sqlite3_file_control()] with this opcode as doing so may disrupt the 
   869 ** operation of the specialized VFSes that do require it.  
   870 **
   871 ** <li>[[SQLITE_FCNTL_WIN32_AV_RETRY]]
   872 ** ^The [SQLITE_FCNTL_WIN32_AV_RETRY] opcode is used to configure automatic
   873 ** retry counts and intervals for certain disk I/O operations for the
   874 ** windows [VFS] in order to provide robustness in the presence of
   875 ** anti-virus programs.  By default, the windows VFS will retry file read,
   876 ** file write, and file delete operations up to 10 times, with a delay
   877 ** of 25 milliseconds before the first retry and with the delay increasing
   878 ** by an additional 25 milliseconds with each subsequent retry.  This
   879 ** opcode allows these two values (10 retries and 25 milliseconds of delay)
   880 ** to be adjusted.  The values are changed for all database connections
   881 ** within the same process.  The argument is a pointer to an array of two
   882 ** integers where the first integer is the new retry count and the second
   883 ** integer is the delay.  If either integer is negative, then the setting
   884 ** is not changed but instead the prior value of that setting is written
   885 ** into the array entry, allowing the current retry settings to be
   886 ** interrogated.  The zDbName parameter is ignored.
   887 **
   888 ** <li>[[SQLITE_FCNTL_PERSIST_WAL]]
   889 ** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the
   890 ** persistent [WAL | Write Ahead Log] setting.  By default, the auxiliary
   891 ** write ahead log ([WAL file]) and shared memory
   892 ** files used for transaction control
   893 ** are automatically deleted when the latest connection to the database
   894 ** closes.  Setting persistent WAL mode causes those files to persist after
   895 ** close.  Persisting the files is useful when other processes that do not
   896 ** have write permission on the directory containing the database file want
   897 ** to read the database file, as the WAL and shared memory files must exist
   898 ** in order for the database to be readable.  The fourth parameter to
   899 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
   900 ** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
   901 ** WAL mode.  If the integer is -1, then it is overwritten with the current
   902 ** WAL persistence setting.
   903 **
   904 ** <li>[[SQLITE_FCNTL_POWERSAFE_OVERWRITE]]
   905 ** ^The [SQLITE_FCNTL_POWERSAFE_OVERWRITE] opcode is used to set or query the
   906 ** persistent "powersafe-overwrite" or "PSOW" setting.  The PSOW setting
   907 ** determines the [SQLITE_IOCAP_POWERSAFE_OVERWRITE] bit of the
   908 ** xDeviceCharacteristics methods. The fourth parameter to
   909 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
   910 ** That integer is 0 to disable zero-damage mode or 1 to enable zero-damage
   911 ** mode.  If the integer is -1, then it is overwritten with the current
   912 ** zero-damage mode setting.
   913 **
   914 ** <li>[[SQLITE_FCNTL_OVERWRITE]]
   915 ** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
   916 ** a write transaction to indicate that, unless it is rolled back for some
   917 ** reason, the entire database file will be overwritten by the current 
   918 ** transaction. This is used by VACUUM operations.
   919 **
   920 ** <li>[[SQLITE_FCNTL_VFSNAME]]
   921 ** ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of
   922 ** all [VFSes] in the VFS stack.  The names are of all VFS shims and the
   923 ** final bottom-level VFS are written into memory obtained from 
   924 ** [sqlite3_malloc()] and the result is stored in the char* variable
   925 ** that the fourth parameter of [sqlite3_file_control()] points to.
   926 ** The caller is responsible for freeing the memory when done.  As with
   927 ** all file-control actions, there is no guarantee that this will actually
   928 ** do anything.  Callers should initialize the char* variable to a NULL
   929 ** pointer in case this file-control is not implemented.  This file-control
   930 ** is intended for diagnostic use only.
   931 **
   932 ** <li>[[SQLITE_FCNTL_VFS_POINTER]]
   933 ** ^The [SQLITE_FCNTL_VFS_POINTER] opcode finds a pointer to the top-level
   934 ** [VFSes] currently in use.  ^(The argument X in
   935 ** sqlite3_file_control(db,SQLITE_FCNTL_VFS_POINTER,X) must be
   936 ** of type "[sqlite3_vfs] **".  This opcodes will set *X
   937 ** to a pointer to the top-level VFS.)^
   938 ** ^When there are multiple VFS shims in the stack, this opcode finds the
   939 ** upper-most shim only.
   940 **
   941 ** <li>[[SQLITE_FCNTL_PRAGMA]]
   942 ** ^Whenever a [PRAGMA] statement is parsed, an [SQLITE_FCNTL_PRAGMA] 
   943 ** file control is sent to the open [sqlite3_file] object corresponding
   944 ** to the database file to which the pragma statement refers. ^The argument
   945 ** to the [SQLITE_FCNTL_PRAGMA] file control is an array of
   946 ** pointers to strings (char**) in which the second element of the array
   947 ** is the name of the pragma and the third element is the argument to the
   948 ** pragma or NULL if the pragma has no argument.  ^The handler for an
   949 ** [SQLITE_FCNTL_PRAGMA] file control can optionally make the first element
   950 ** of the char** argument point to a string obtained from [sqlite3_mprintf()]
   951 ** or the equivalent and that string will become the result of the pragma or
   952 ** the error message if the pragma fails. ^If the
   953 ** [SQLITE_FCNTL_PRAGMA] file control returns [SQLITE_NOTFOUND], then normal 
   954 ** [PRAGMA] processing continues.  ^If the [SQLITE_FCNTL_PRAGMA]
   955 ** file control returns [SQLITE_OK], then the parser assumes that the
   956 ** VFS has handled the PRAGMA itself and the parser generates a no-op
   957 ** prepared statement if result string is NULL, or that returns a copy
   958 ** of the result string if the string is non-NULL.
   959 ** ^If the [SQLITE_FCNTL_PRAGMA] file control returns
   960 ** any result code other than [SQLITE_OK] or [SQLITE_NOTFOUND], that means
   961 ** that the VFS encountered an error while handling the [PRAGMA] and the
   962 ** compilation of the PRAGMA fails with an error.  ^The [SQLITE_FCNTL_PRAGMA]
   963 ** file control occurs at the beginning of pragma statement analysis and so
   964 ** it is able to override built-in [PRAGMA] statements.
   965 **
   966 ** <li>[[SQLITE_FCNTL_BUSYHANDLER]]
   967 ** ^The [SQLITE_FCNTL_BUSYHANDLER]
   968 ** file-control may be invoked by SQLite on the database file handle
   969 ** shortly after it is opened in order to provide a custom VFS with access
   970 ** to the connections busy-handler callback. The argument is of type (void **)
   971 ** - an array of two (void *) values. The first (void *) actually points
   972 ** to a function of type (int (*)(void *)). In order to invoke the connections
   973 ** busy-handler, this function should be invoked with the second (void *) in
   974 ** the array as the only argument. If it returns non-zero, then the operation
   975 ** should be retried. If it returns zero, the custom VFS should abandon the
   976 ** current operation.
   977 **
   978 ** <li>[[SQLITE_FCNTL_TEMPFILENAME]]
   979 ** ^Application can invoke the [SQLITE_FCNTL_TEMPFILENAME] file-control
   980 ** to have SQLite generate a
   981 ** temporary filename using the same algorithm that is followed to generate
   982 ** temporary filenames for TEMP tables and other internal uses.  The
   983 ** argument should be a char** which will be filled with the filename
   984 ** written into memory obtained from [sqlite3_malloc()].  The caller should
   985 ** invoke [sqlite3_free()] on the result to avoid a memory leak.
   986 **
   987 ** <li>[[SQLITE_FCNTL_MMAP_SIZE]]
   988 ** The [SQLITE_FCNTL_MMAP_SIZE] file control is used to query or set the
   989 ** maximum number of bytes that will be used for memory-mapped I/O.
   990 ** The argument is a pointer to a value of type sqlite3_int64 that
   991 ** is an advisory maximum number of bytes in the file to memory map.  The
   992 ** pointer is overwritten with the old value.  The limit is not changed if
   993 ** the value originally pointed to is negative, and so the current limit 
   994 ** can be queried by passing in a pointer to a negative number.  This
   995 ** file-control is used internally to implement [PRAGMA mmap_size].
   996 **
   997 ** <li>[[SQLITE_FCNTL_TRACE]]
   998 ** The [SQLITE_FCNTL_TRACE] file control provides advisory information
   999 ** to the VFS about what the higher layers of the SQLite stack are doing.
  1000 ** This file control is used by some VFS activity tracing [shims].
  1001 ** The argument is a zero-terminated string.  Higher layers in the
  1002 ** SQLite stack may generate instances of this file control if
  1003 ** the [SQLITE_USE_FCNTL_TRACE] compile-time option is enabled.
  1004 **
  1005 ** <li>[[SQLITE_FCNTL_HAS_MOVED]]
  1006 ** The [SQLITE_FCNTL_HAS_MOVED] file control interprets its argument as a
  1007 ** pointer to an integer and it writes a boolean into that integer depending
  1008 ** on whether or not the file has been renamed, moved, or deleted since it
  1009 ** was first opened.
  1010 **
  1011 ** <li>[[SQLITE_FCNTL_WIN32_GET_HANDLE]]
  1012 ** The [SQLITE_FCNTL_WIN32_GET_HANDLE] opcode can be used to obtain the
  1013 ** underlying native file handle associated with a file handle.  This file
  1014 ** control interprets its argument as a pointer to a native file handle and
  1015 ** writes the resulting value there.
  1016 **
  1017 ** <li>[[SQLITE_FCNTL_WIN32_SET_HANDLE]]
  1018 ** The [SQLITE_FCNTL_WIN32_SET_HANDLE] opcode is used for debugging.  This
  1019 ** opcode causes the xFileControl method to swap the file handle with the one
  1020 ** pointed to by the pArg argument.  This capability is used during testing
  1021 ** and only needs to be supported when SQLITE_TEST is defined.
  1022 **
  1023 ** <li>[[SQLITE_FCNTL_WAL_BLOCK]]
  1024 ** The [SQLITE_FCNTL_WAL_BLOCK] is a signal to the VFS layer that it might
  1025 ** be advantageous to block on the next WAL lock if the lock is not immediately
  1026 ** available.  The WAL subsystem issues this signal during rare
  1027 ** circumstances in order to fix a problem with priority inversion.
  1028 ** Applications should <em>not</em> use this file-control.
  1029 **
  1030 ** <li>[[SQLITE_FCNTL_ZIPVFS]]
  1031 ** The [SQLITE_FCNTL_ZIPVFS] opcode is implemented by zipvfs only. All other
  1032 ** VFS should return SQLITE_NOTFOUND for this opcode.
  1033 **
  1034 ** <li>[[SQLITE_FCNTL_RBU]]
  1035 ** The [SQLITE_FCNTL_RBU] opcode is implemented by the special VFS used by
  1036 ** the RBU extension only.  All other VFS should return SQLITE_NOTFOUND for
  1037 ** this opcode.  
  1038 **
  1039 ** <li>[[SQLITE_FCNTL_BEGIN_ATOMIC_WRITE]]
  1040 ** If the [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE] opcode returns SQLITE_OK, then
  1041 ** the file descriptor is placed in "batch write mode", which
  1042 ** means all subsequent write operations will be deferred and done
  1043 ** atomically at the next [SQLITE_FCNTL_COMMIT_ATOMIC_WRITE].  Systems
  1044 ** that do not support batch atomic writes will return SQLITE_NOTFOUND.
  1045 ** ^Following a successful SQLITE_FCNTL_BEGIN_ATOMIC_WRITE and prior to
  1046 ** the closing [SQLITE_FCNTL_COMMIT_ATOMIC_WRITE] or
  1047 ** [SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE], SQLite will make
  1048 ** no VFS interface calls on the same [sqlite3_file] file descriptor
  1049 ** except for calls to the xWrite method and the xFileControl method
  1050 ** with [SQLITE_FCNTL_SIZE_HINT].
  1051 **
  1052 ** <li>[[SQLITE_FCNTL_COMMIT_ATOMIC_WRITE]]
  1053 ** The [SQLITE_FCNTL_COMMIT_ATOMIC_WRITE] opcode causes all write
  1054 ** operations since the previous successful call to 
  1055 ** [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE] to be performed atomically.
  1056 ** This file control returns [SQLITE_OK] if and only if the writes were
  1057 ** all performed successfully and have been committed to persistent storage.
  1058 ** ^Regardless of whether or not it is successful, this file control takes
  1059 ** the file descriptor out of batch write mode so that all subsequent
  1060 ** write operations are independent.
  1061 ** ^SQLite will never invoke SQLITE_FCNTL_COMMIT_ATOMIC_WRITE without
  1062 ** a prior successful call to [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE].
  1063 **
  1064 ** <li>[[SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE]]
  1065 ** The [SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE] opcode causes all write
  1066 ** operations since the previous successful call to 
  1067 ** [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE] to be rolled back.
  1068 ** ^This file control takes the file descriptor out of batch write mode
  1069 ** so that all subsequent write operations are independent.
  1070 ** ^SQLite will never invoke SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE without
  1071 ** a prior successful call to [SQLITE_FCNTL_BEGIN_ATOMIC_WRITE].
  1072 **
  1073 ** <li>[[SQLITE_FCNTL_LOCK_TIMEOUT]]
  1074 ** The [SQLITE_FCNTL_LOCK_TIMEOUT] opcode causes attempts to obtain
  1075 ** a file lock using the xLock or xShmLock methods of the VFS to wait
  1076 ** for up to M milliseconds before failing, where M is the single 
  1077 ** unsigned integer parameter.
  1078 **
  1079 ** <li>[[SQLITE_FCNTL_DATA_VERSION]]
  1080 ** The [SQLITE_FCNTL_DATA_VERSION] opcode is used to detect changes to
  1081 ** a database file.  The argument is a pointer to a 32-bit unsigned integer.
  1082 ** The "data version" for the pager is written into the pointer.  The
  1083 ** "data version" changes whenever any change occurs to the corresponding
  1084 ** database file, either through SQL statements on the same database
  1085 ** connection or through transactions committed by separate database
  1086 ** connections possibly in other processes. The [sqlite3_total_changes()]
  1087 ** interface can be used to find if any database on the connection has changed,
  1088 ** but that interface responds to changes on TEMP as well as MAIN and does
  1089 ** not provide a mechanism to detect changes to MAIN only.  Also, the
  1090 ** [sqlite3_total_changes()] interface responds to internal changes only and
  1091 ** omits changes made by other database connections.  The
  1092 ** [PRAGMA data_version] command provide a mechanism to detect changes to
  1093 ** a single attached database that occur due to other database connections,
  1094 ** but omits changes implemented by the database connection on which it is
  1095 ** called.  This file control is the only mechanism to detect changes that
  1096 ** happen either internally or externally and that are associated with
  1097 ** a particular attached database.
  1098 ** </ul>
  1099 */
  1100 #define SQLITE_FCNTL_LOCKSTATE               1
  1101 #define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
  1102 #define SQLITE_FCNTL_SET_LOCKPROXYFILE       3
  1103 #define SQLITE_FCNTL_LAST_ERRNO              4
  1104 #define SQLITE_FCNTL_SIZE_HINT               5
  1105 #define SQLITE_FCNTL_CHUNK_SIZE              6
  1106 #define SQLITE_FCNTL_FILE_POINTER            7
  1107 #define SQLITE_FCNTL_SYNC_OMITTED            8
  1108 #define SQLITE_FCNTL_WIN32_AV_RETRY          9
  1109 #define SQLITE_FCNTL_PERSIST_WAL            10
  1110 #define SQLITE_FCNTL_OVERWRITE              11
  1111 #define SQLITE_FCNTL_VFSNAME                12
  1112 #define SQLITE_FCNTL_POWERSAFE_OVERWRITE    13
  1113 #define SQLITE_FCNTL_PRAGMA                 14
  1114 #define SQLITE_FCNTL_BUSYHANDLER            15
  1115 #define SQLITE_FCNTL_TEMPFILENAME           16
  1116 #define SQLITE_FCNTL_MMAP_SIZE              18
  1117 #define SQLITE_FCNTL_TRACE                  19
  1118 #define SQLITE_FCNTL_HAS_MOVED              20
  1119 #define SQLITE_FCNTL_SYNC                   21
  1120 #define SQLITE_FCNTL_COMMIT_PHASETWO        22
  1121 #define SQLITE_FCNTL_WIN32_SET_HANDLE       23
  1122 #define SQLITE_FCNTL_WAL_BLOCK              24
  1123 #define SQLITE_FCNTL_ZIPVFS                 25
  1124 #define SQLITE_FCNTL_RBU                    26
  1125 #define SQLITE_FCNTL_VFS_POINTER            27
  1126 #define SQLITE_FCNTL_JOURNAL_POINTER        28
  1127 #define SQLITE_FCNTL_WIN32_GET_HANDLE       29
  1128 #define SQLITE_FCNTL_PDB                    30
  1129 #define SQLITE_FCNTL_BEGIN_ATOMIC_WRITE     31
  1130 #define SQLITE_FCNTL_COMMIT_ATOMIC_WRITE    32
  1131 #define SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE  33
  1132 #define SQLITE_FCNTL_LOCK_TIMEOUT           34
  1133 #define SQLITE_FCNTL_DATA_VERSION           35
  1134 
  1135 /* deprecated names */
  1136 #define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
  1137 #define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
  1138 #define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO
  1139 
  1140 
  1141 /*
  1142 ** CAPI3REF: Mutex Handle
  1143 **
  1144 ** The mutex module within SQLite defines [sqlite3_mutex] to be an
  1145 ** abstract type for a mutex object.  The SQLite core never looks
  1146 ** at the internal representation of an [sqlite3_mutex].  It only
  1147 ** deals with pointers to the [sqlite3_mutex] object.
  1148 **
  1149 ** Mutexes are created using [sqlite3_mutex_alloc()].
  1150 */
  1151 typedef struct sqlite3_mutex sqlite3_mutex;
  1152 
  1153 /*
  1154 ** CAPI3REF: Loadable Extension Thunk
  1155 **
  1156 ** A pointer to the opaque sqlite3_api_routines structure is passed as
  1157 ** the third parameter to entry points of [loadable extensions].  This
  1158 ** structure must be typedefed in order to work around compiler warnings
  1159 ** on some platforms.
  1160 */
  1161 typedef struct sqlite3_api_routines sqlite3_api_routines;
  1162 
  1163 /*
  1164 ** CAPI3REF: OS Interface Object
  1165 **
  1166 ** An instance of the sqlite3_vfs object defines the interface between
  1167 ** the SQLite core and the underlying operating system.  The "vfs"
  1168 ** in the name of the object stands for "virtual file system".  See
  1169 ** the [VFS | VFS documentation] for further information.
  1170 **
  1171 ** The VFS interface is sometimes extended by adding new methods onto
  1172 ** the end.  Each time such an extension occurs, the iVersion field
  1173 ** is incremented.  The iVersion value started out as 1 in
  1174 ** SQLite [version 3.5.0] on [dateof:3.5.0], then increased to 2
  1175 ** with SQLite [version 3.7.0] on [dateof:3.7.0], and then increased
  1176 ** to 3 with SQLite [version 3.7.6] on [dateof:3.7.6].  Additional fields
  1177 ** may be appended to the sqlite3_vfs object and the iVersion value
  1178 ** may increase again in future versions of SQLite.
  1179 ** Note that the structure
  1180 ** of the sqlite3_vfs object changes in the transition from
  1181 ** SQLite [version 3.5.9] to [version 3.6.0] on [dateof:3.6.0]
  1182 ** and yet the iVersion field was not modified.
  1183 **
  1184 ** The szOsFile field is the size of the subclassed [sqlite3_file]
  1185 ** structure used by this VFS.  mxPathname is the maximum length of
  1186 ** a pathname in this VFS.
  1187 **
  1188 ** Registered sqlite3_vfs objects are kept on a linked list formed by
  1189 ** the pNext pointer.  The [sqlite3_vfs_register()]
  1190 ** and [sqlite3_vfs_unregister()] interfaces manage this list
  1191 ** in a thread-safe way.  The [sqlite3_vfs_find()] interface
  1192 ** searches the list.  Neither the application code nor the VFS
  1193 ** implementation should use the pNext pointer.
  1194 **
  1195 ** The pNext field is the only field in the sqlite3_vfs
  1196 ** structure that SQLite will ever modify.  SQLite will only access
  1197 ** or modify this field while holding a particular static mutex.
  1198 ** The application should never modify anything within the sqlite3_vfs
  1199 ** object once the object has been registered.
  1200 **
  1201 ** The zName field holds the name of the VFS module.  The name must
  1202 ** be unique across all VFS modules.
  1203 **
  1204 ** [[sqlite3_vfs.xOpen]]
  1205 ** ^SQLite guarantees that the zFilename parameter to xOpen
  1206 ** is either a NULL pointer or string obtained
  1207 ** from xFullPathname() with an optional suffix added.
  1208 ** ^If a suffix is added to the zFilename parameter, it will
  1209 ** consist of a single "-" character followed by no more than
  1210 ** 11 alphanumeric and/or "-" characters.
  1211 ** ^SQLite further guarantees that
  1212 ** the string will be valid and unchanged until xClose() is
  1213 ** called. Because of the previous sentence,
  1214 ** the [sqlite3_file] can safely store a pointer to the
  1215 ** filename if it needs to remember the filename for some reason.
  1216 ** If the zFilename parameter to xOpen is a NULL pointer then xOpen
  1217 ** must invent its own temporary name for the file.  ^Whenever the 
  1218 ** xFilename parameter is NULL it will also be the case that the
  1219 ** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
  1220 **
  1221 ** The flags argument to xOpen() includes all bits set in
  1222 ** the flags argument to [sqlite3_open_v2()].  Or if [sqlite3_open()]
  1223 ** or [sqlite3_open16()] is used, then flags includes at least
  1224 ** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]. 
  1225 ** If xOpen() opens a file read-only then it sets *pOutFlags to
  1226 ** include [SQLITE_OPEN_READONLY].  Other bits in *pOutFlags may be set.
  1227 **
  1228 ** ^(SQLite will also add one of the following flags to the xOpen()
  1229 ** call, depending on the object being opened:
  1230 **
  1231 ** <ul>
  1232 ** <li>  [SQLITE_OPEN_MAIN_DB]
  1233 ** <li>  [SQLITE_OPEN_MAIN_JOURNAL]
  1234 ** <li>  [SQLITE_OPEN_TEMP_DB]
  1235 ** <li>  [SQLITE_OPEN_TEMP_JOURNAL]
  1236 ** <li>  [SQLITE_OPEN_TRANSIENT_DB]
  1237 ** <li>  [SQLITE_OPEN_SUBJOURNAL]
  1238 ** <li>  [SQLITE_OPEN_MASTER_JOURNAL]
  1239 ** <li>  [SQLITE_OPEN_WAL]
  1240 ** </ul>)^
  1241 **
  1242 ** The file I/O implementation can use the object type flags to
  1243 ** change the way it deals with files.  For example, an application
  1244 ** that does not care about crash recovery or rollback might make
  1245 ** the open of a journal file a no-op.  Writes to this journal would
  1246 ** also be no-ops, and any attempt to read the journal would return
  1247 ** SQLITE_IOERR.  Or the implementation might recognize that a database
  1248 ** file will be doing page-aligned sector reads and writes in a random
  1249 ** order and set up its I/O subsystem accordingly.
  1250 **
  1251 ** SQLite might also add one of the following flags to the xOpen method:
  1252 **
  1253 ** <ul>
  1254 ** <li> [SQLITE_OPEN_DELETEONCLOSE]
  1255 ** <li> [SQLITE_OPEN_EXCLUSIVE]
  1256 ** </ul>
  1257 **
  1258 ** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
  1259 ** deleted when it is closed.  ^The [SQLITE_OPEN_DELETEONCLOSE]
  1260 ** will be set for TEMP databases and their journals, transient
  1261 ** databases, and subjournals.
  1262 **
  1263 ** ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction
  1264 ** with the [SQLITE_OPEN_CREATE] flag, which are both directly
  1265 ** analogous to the O_EXCL and O_CREAT flags of the POSIX open()
  1266 ** API.  The SQLITE_OPEN_EXCLUSIVE flag, when paired with the 
  1267 ** SQLITE_OPEN_CREATE, is used to indicate that file should always
  1268 ** be created, and that it is an error if it already exists.
  1269 ** It is <i>not</i> used to indicate the file should be opened 
  1270 ** for exclusive access.
  1271 **
  1272 ** ^At least szOsFile bytes of memory are allocated by SQLite
  1273 ** to hold the  [sqlite3_file] structure passed as the third
  1274 ** argument to xOpen.  The xOpen method does not have to
  1275 ** allocate the structure; it should just fill it in.  Note that
  1276 ** the xOpen method must set the sqlite3_file.pMethods to either
  1277 ** a valid [sqlite3_io_methods] object or to NULL.  xOpen must do
  1278 ** this even if the open fails.  SQLite expects that the sqlite3_file.pMethods
  1279 ** element will be valid after xOpen returns regardless of the success
  1280 ** or failure of the xOpen call.
  1281 **
  1282 ** [[sqlite3_vfs.xAccess]]
  1283 ** ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
  1284 ** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
  1285 ** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
  1286 ** to test whether a file is at least readable.   The file can be a
  1287 ** directory.
  1288 **
  1289 ** ^SQLite will always allocate at least mxPathname+1 bytes for the
  1290 ** output buffer xFullPathname.  The exact size of the output buffer
  1291 ** is also passed as a parameter to both  methods. If the output buffer
  1292 ** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
  1293 ** handled as a fatal error by SQLite, vfs implementations should endeavor
  1294 ** to prevent this by setting mxPathname to a sufficiently large value.
  1295 **
  1296 ** The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64()
  1297 ** interfaces are not strictly a part of the filesystem, but they are
  1298 ** included in the VFS structure for completeness.
  1299 ** The xRandomness() function attempts to return nBytes bytes
  1300 ** of good-quality randomness into zOut.  The return value is
  1301 ** the actual number of bytes of randomness obtained.
  1302 ** The xSleep() method causes the calling thread to sleep for at
  1303 ** least the number of microseconds given.  ^The xCurrentTime()
  1304 ** method returns a Julian Day Number for the current date and time as
  1305 ** a floating point value.
  1306 ** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
  1307 ** Day Number multiplied by 86400000 (the number of milliseconds in 
  1308 ** a 24-hour day).  
  1309 ** ^SQLite will use the xCurrentTimeInt64() method to get the current
  1310 ** date and time if that method is available (if iVersion is 2 or 
  1311 ** greater and the function pointer is not NULL) and will fall back
  1312 ** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
  1313 **
  1314 ** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
  1315 ** are not used by the SQLite core.  These optional interfaces are provided
  1316 ** by some VFSes to facilitate testing of the VFS code. By overriding 
  1317 ** system calls with functions under its control, a test program can
  1318 ** simulate faults and error conditions that would otherwise be difficult
  1319 ** or impossible to induce.  The set of system calls that can be overridden
  1320 ** varies from one VFS to another, and from one version of the same VFS to the
  1321 ** next.  Applications that use these interfaces must be prepared for any
  1322 ** or all of these interfaces to be NULL or for their behavior to change
  1323 ** from one release to the next.  Applications must not attempt to access
  1324 ** any of these methods if the iVersion of the VFS is less than 3.
  1325 */
  1326 typedef struct sqlite3_vfs sqlite3_vfs;
  1327 typedef void (*sqlite3_syscall_ptr)(void);
  1328 struct sqlite3_vfs {
  1329   int iVersion;            /* Structure version number (currently 3) */
  1330   int szOsFile;            /* Size of subclassed sqlite3_file */
  1331   int mxPathname;          /* Maximum file pathname length */
  1332   sqlite3_vfs *pNext;      /* Next registered VFS */
  1333   const char *zName;       /* Name of this virtual file system */
  1334   void *pAppData;          /* Pointer to application-specific data */
  1335   int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
  1336                int flags, int *pOutFlags);
  1337   int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
  1338   int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
  1339   int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
  1340   void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
  1341   void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
  1342   void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
  1343   void (*xDlClose)(sqlite3_vfs*, void*);
  1344   int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
  1345   int (*xSleep)(sqlite3_vfs*, int microseconds);
  1346   int (*xCurrentTime)(sqlite3_vfs*, double*);
  1347   int (*xGetLastError)(sqlite3_vfs*, int, char *);
  1348   /*
  1349   ** The methods above are in version 1 of the sqlite_vfs object
  1350   ** definition.  Those that follow are added in version 2 or later
  1351   */
  1352   int (*xCurrentTimeInt64)(sqlite3_vfs*, sqlite3_int64*);
  1353   /*
  1354   ** The methods above are in versions 1 and 2 of the sqlite_vfs object.
  1355   ** Those below are for version 3 and greater.
  1356   */
  1357   int (*xSetSystemCall)(sqlite3_vfs*, const char *zName, sqlite3_syscall_ptr);
  1358   sqlite3_syscall_ptr (*xGetSystemCall)(sqlite3_vfs*, const char *zName);
  1359   const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
  1360   /*
  1361   ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
  1362   ** New fields may be appended in future versions.  The iVersion
  1363   ** value will increment whenever this happens. 
  1364   */
  1365 };
  1366 
  1367 /*
  1368 ** CAPI3REF: Flags for the xAccess VFS method
  1369 **
  1370 ** These integer constants can be used as the third parameter to
  1371 ** the xAccess method of an [sqlite3_vfs] object.  They determine
  1372 ** what kind of permissions the xAccess method is looking for.
  1373 ** With SQLITE_ACCESS_EXISTS, the xAccess method
  1374 ** simply checks whether the file exists.
  1375 ** With SQLITE_ACCESS_READWRITE, the xAccess method
  1376 ** checks whether the named directory is both readable and writable
  1377 ** (in other words, if files can be added, removed, and renamed within
  1378 ** the directory).
  1379 ** The SQLITE_ACCESS_READWRITE constant is currently used only by the
  1380 ** [temp_store_directory pragma], though this could change in a future
  1381 ** release of SQLite.
  1382 ** With SQLITE_ACCESS_READ, the xAccess method
  1383 ** checks whether the file is readable.  The SQLITE_ACCESS_READ constant is
  1384 ** currently unused, though it might be used in a future release of
  1385 ** SQLite.
  1386 */
  1387 #define SQLITE_ACCESS_EXISTS    0
  1388 #define SQLITE_ACCESS_READWRITE 1   /* Used by PRAGMA temp_store_directory */
  1389 #define SQLITE_ACCESS_READ      2   /* Unused */
  1390 
  1391 /*
  1392 ** CAPI3REF: Flags for the xShmLock VFS method
  1393 **
  1394 ** These integer constants define the various locking operations
  1395 ** allowed by the xShmLock method of [sqlite3_io_methods].  The
  1396 ** following are the only legal combinations of flags to the
  1397 ** xShmLock method:
  1398 **
  1399 ** <ul>
  1400 ** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_SHARED
  1401 ** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE
  1402 ** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED
  1403 ** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE
  1404 ** </ul>
  1405 **
  1406 ** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
  1407 ** was given on the corresponding lock.  
  1408 **
  1409 ** The xShmLock method can transition between unlocked and SHARED or
  1410 ** between unlocked and EXCLUSIVE.  It cannot transition between SHARED
  1411 ** and EXCLUSIVE.
  1412 */
  1413 #define SQLITE_SHM_UNLOCK       1
  1414 #define SQLITE_SHM_LOCK         2
  1415 #define SQLITE_SHM_SHARED       4
  1416 #define SQLITE_SHM_EXCLUSIVE    8
  1417 
  1418 /*
  1419 ** CAPI3REF: Maximum xShmLock index
  1420 **
  1421 ** The xShmLock method on [sqlite3_io_methods] may use values
  1422 ** between 0 and this upper bound as its "offset" argument.
  1423 ** The SQLite core will never attempt to acquire or release a
  1424 ** lock outside of this range
  1425 */
  1426 #define SQLITE_SHM_NLOCK        8
  1427 
  1428 
  1429 /*
  1430 ** CAPI3REF: Initialize The SQLite Library
  1431 **
  1432 ** ^The sqlite3_initialize() routine initializes the
  1433 ** SQLite library.  ^The sqlite3_shutdown() routine
  1434 ** deallocates any resources that were allocated by sqlite3_initialize().
  1435 ** These routines are designed to aid in process initialization and
  1436 ** shutdown on embedded systems.  Workstation applications using
  1437 ** SQLite normally do not need to invoke either of these routines.
  1438 **
  1439 ** A call to sqlite3_initialize() is an "effective" call if it is
  1440 ** the first time sqlite3_initialize() is invoked during the lifetime of
  1441 ** the process, or if it is the first time sqlite3_initialize() is invoked
  1442 ** following a call to sqlite3_shutdown().  ^(Only an effective call
  1443 ** of sqlite3_initialize() does any initialization.  All other calls
  1444 ** are harmless no-ops.)^
  1445 **
  1446 ** A call to sqlite3_shutdown() is an "effective" call if it is the first
  1447 ** call to sqlite3_shutdown() since the last sqlite3_initialize().  ^(Only
  1448 ** an effective call to sqlite3_shutdown() does any deinitialization.
  1449 ** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^
  1450 **
  1451 ** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()
  1452 ** is not.  The sqlite3_shutdown() interface must only be called from a
  1453 ** single thread.  All open [database connections] must be closed and all
  1454 ** other SQLite resources must be deallocated prior to invoking
  1455 ** sqlite3_shutdown().
  1456 **
  1457 ** Among other things, ^sqlite3_initialize() will invoke
  1458 ** sqlite3_os_init().  Similarly, ^sqlite3_shutdown()
  1459 ** will invoke sqlite3_os_end().
  1460 **
  1461 ** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.
  1462 ** ^If for some reason, sqlite3_initialize() is unable to initialize
  1463 ** the library (perhaps it is unable to allocate a needed resource such
  1464 ** as a mutex) it returns an [error code] other than [SQLITE_OK].
  1465 **
  1466 ** ^The sqlite3_initialize() routine is called internally by many other
  1467 ** SQLite interfaces so that an application usually does not need to
  1468 ** invoke sqlite3_initialize() directly.  For example, [sqlite3_open()]
  1469 ** calls sqlite3_initialize() so the SQLite library will be automatically
  1470 ** initialized when [sqlite3_open()] is called if it has not be initialized
  1471 ** already.  ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
  1472 ** compile-time option, then the automatic calls to sqlite3_initialize()
  1473 ** are omitted and the application must call sqlite3_initialize() directly
  1474 ** prior to using any other SQLite interface.  For maximum portability,
  1475 ** it is recommended that applications always invoke sqlite3_initialize()
  1476 ** directly prior to using any other SQLite interface.  Future releases
  1477 ** of SQLite may require this.  In other words, the behavior exhibited
  1478 ** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
  1479 ** default behavior in some future release of SQLite.
  1480 **
  1481 ** The sqlite3_os_init() routine does operating-system specific
  1482 ** initialization of the SQLite library.  The sqlite3_os_end()
  1483 ** routine undoes the effect of sqlite3_os_init().  Typical tasks
  1484 ** performed by these routines include allocation or deallocation
  1485 ** of static resources, initialization of global variables,
  1486 ** setting up a default [sqlite3_vfs] module, or setting up
  1487 ** a default configuration using [sqlite3_config()].
  1488 **
  1489 ** The application should never invoke either sqlite3_os_init()
  1490 ** or sqlite3_os_end() directly.  The application should only invoke
  1491 ** sqlite3_initialize() and sqlite3_shutdown().  The sqlite3_os_init()
  1492 ** interface is called automatically by sqlite3_initialize() and
  1493 ** sqlite3_os_end() is called by sqlite3_shutdown().  Appropriate
  1494 ** implementations for sqlite3_os_init() and sqlite3_os_end()
  1495 ** are built into SQLite when it is compiled for Unix, Windows, or OS/2.
  1496 ** When [custom builds | built for other platforms]
  1497 ** (using the [SQLITE_OS_OTHER=1] compile-time
  1498 ** option) the application must supply a suitable implementation for
  1499 ** sqlite3_os_init() and sqlite3_os_end().  An application-supplied
  1500 ** implementation of sqlite3_os_init() or sqlite3_os_end()
  1501 ** must return [SQLITE_OK] on success and some other [error code] upon
  1502 ** failure.
  1503 */
  1504 SQLITE_API int sqlite3_initialize(void);
  1505 SQLITE_API int sqlite3_shutdown(void);
  1506 SQLITE_API int sqlite3_os_init(void);
  1507 SQLITE_API int sqlite3_os_end(void);
  1508 
  1509 /*
  1510 ** CAPI3REF: Configuring The SQLite Library
  1511 **
  1512 ** The sqlite3_config() interface is used to make global configuration
  1513 ** changes to SQLite in order to tune SQLite to the specific needs of
  1514 ** the application.  The default configuration is recommended for most
  1515 ** applications and so this routine is usually not necessary.  It is
  1516 ** provided to support rare applications with unusual needs.
  1517 **
  1518 ** <b>The sqlite3_config() interface is not threadsafe. The application
  1519 ** must ensure that no other SQLite interfaces are invoked by other
  1520 ** threads while sqlite3_config() is running.</b>
  1521 **
  1522 ** The sqlite3_config() interface
  1523 ** may only be invoked prior to library initialization using
  1524 ** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
  1525 ** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
  1526 ** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.
  1527 ** Note, however, that ^sqlite3_config() can be called as part of the
  1528 ** implementation of an application-defined [sqlite3_os_init()].
  1529 **
  1530 ** The first argument to sqlite3_config() is an integer
  1531 ** [configuration option] that determines
  1532 ** what property of SQLite is to be configured.  Subsequent arguments
  1533 ** vary depending on the [configuration option]
  1534 ** in the first argument.
  1535 **
  1536 ** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
  1537 ** ^If the option is unknown or SQLite is unable to set the option
  1538 ** then this routine returns a non-zero [error code].
  1539 */
  1540 SQLITE_API int sqlite3_config(int, ...);
  1541 
  1542 /*
  1543 ** CAPI3REF: Configure database connections
  1544 ** METHOD: sqlite3
  1545 **
  1546 ** The sqlite3_db_config() interface is used to make configuration
  1547 ** changes to a [database connection].  The interface is similar to
  1548 ** [sqlite3_config()] except that the changes apply to a single
  1549 ** [database connection] (specified in the first argument).
  1550 **
  1551 ** The second argument to sqlite3_db_config(D,V,...)  is the
  1552 ** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code 
  1553 ** that indicates what aspect of the [database connection] is being configured.
  1554 ** Subsequent arguments vary depending on the configuration verb.
  1555 **
  1556 ** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
  1557 ** the call is considered successful.
  1558 */
  1559 SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);
  1560 
  1561 /*
  1562 ** CAPI3REF: Memory Allocation Routines
  1563 **
  1564 ** An instance of this object defines the interface between SQLite
  1565 ** and low-level memory allocation routines.
  1566 **
  1567 ** This object is used in only one place in the SQLite interface.
  1568 ** A pointer to an instance of this object is the argument to
  1569 ** [sqlite3_config()] when the configuration option is
  1570 ** [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC].  
  1571 ** By creating an instance of this object
  1572 ** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])
  1573 ** during configuration, an application can specify an alternative
  1574 ** memory allocation subsystem for SQLite to use for all of its
  1575 ** dynamic memory needs.
  1576 **
  1577 ** Note that SQLite comes with several [built-in memory allocators]
  1578 ** that are perfectly adequate for the overwhelming majority of applications
  1579 ** and that this object is only useful to a tiny minority of applications
  1580 ** with specialized memory allocation requirements.  This object is
  1581 ** also used during testing of SQLite in order to specify an alternative
  1582 ** memory allocator that simulates memory out-of-memory conditions in
  1583 ** order to verify that SQLite recovers gracefully from such
  1584 ** conditions.
  1585 **
  1586 ** The xMalloc, xRealloc, and xFree methods must work like the
  1587 ** malloc(), realloc() and free() functions from the standard C library.
  1588 ** ^SQLite guarantees that the second argument to
  1589 ** xRealloc is always a value returned by a prior call to xRoundup.
  1590 **
  1591 ** xSize should return the allocated size of a memory allocation
  1592 ** previously obtained from xMalloc or xRealloc.  The allocated size
  1593 ** is always at least as big as the requested size but may be larger.
  1594 **
  1595 ** The xRoundup method returns what would be the allocated size of
  1596 ** a memory allocation given a particular requested size.  Most memory
  1597 ** allocators round up memory allocations at least to the next multiple
  1598 ** of 8.  Some allocators round up to a larger multiple or to a power of 2.
  1599 ** Every memory allocation request coming in through [sqlite3_malloc()]
  1600 ** or [sqlite3_realloc()] first calls xRoundup.  If xRoundup returns 0, 
  1601 ** that causes the corresponding memory allocation to fail.
  1602 **
  1603 ** The xInit method initializes the memory allocator.  For example,
  1604 ** it might allocate any require mutexes or initialize internal data
  1605 ** structures.  The xShutdown method is invoked (indirectly) by
  1606 ** [sqlite3_shutdown()] and should deallocate any resources acquired
  1607 ** by xInit.  The pAppData pointer is used as the only parameter to
  1608 ** xInit and xShutdown.
  1609 **
  1610 ** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes
  1611 ** the xInit method, so the xInit method need not be threadsafe.  The
  1612 ** xShutdown method is only called from [sqlite3_shutdown()] so it does
  1613 ** not need to be threadsafe either.  For all other methods, SQLite
  1614 ** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the
  1615 ** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which
  1616 ** it is by default) and so the methods are automatically serialized.
  1617 ** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other
  1618 ** methods must be threadsafe or else make their own arrangements for
  1619 ** serialization.
  1620 **
  1621 ** SQLite will never invoke xInit() more than once without an intervening
  1622 ** call to xShutdown().
  1623 */
  1624 typedef struct sqlite3_mem_methods sqlite3_mem_methods;
  1625 struct sqlite3_mem_methods {
  1626   void *(*xMalloc)(int);         /* Memory allocation function */
  1627   void (*xFree)(void*);          /* Free a prior allocation */
  1628   void *(*xRealloc)(void*,int);  /* Resize an allocation */
  1629   int (*xSize)(void*);           /* Return the size of an allocation */
  1630   int (*xRoundup)(int);          /* Round up request size to allocation size */
  1631   int (*xInit)(void*);           /* Initialize the memory allocator */
  1632   void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
  1633   void *pAppData;                /* Argument to xInit() and xShutdown() */
  1634 };
  1635 
  1636 /*
  1637 ** CAPI3REF: Configuration Options
  1638 ** KEYWORDS: {configuration option}
  1639 **
  1640 ** These constants are the available integer configuration options that
  1641 ** can be passed as the first argument to the [sqlite3_config()] interface.
  1642 **
  1643 ** New configuration options may be added in future releases of SQLite.
  1644 ** Existing configuration options might be discontinued.  Applications
  1645 ** should check the return code from [sqlite3_config()] to make sure that
  1646 ** the call worked.  The [sqlite3_config()] interface will return a
  1647 ** non-zero [error code] if a discontinued or unsupported configuration option
  1648 ** is invoked.
  1649 **
  1650 ** <dl>
  1651 ** [[SQLITE_CONFIG_SINGLETHREAD]] <dt>SQLITE_CONFIG_SINGLETHREAD</dt>
  1652 ** <dd>There are no arguments to this option.  ^This option sets the
  1653 ** [threading mode] to Single-thread.  In other words, it disables
  1654 ** all mutexing and puts SQLite into a mode where it can only be used
  1655 ** by a single thread.   ^If SQLite is compiled with
  1656 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1657 ** it is not possible to change the [threading mode] from its default
  1658 ** value of Single-thread and so [sqlite3_config()] will return 
  1659 ** [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD
  1660 ** configuration option.</dd>
  1661 **
  1662 ** [[SQLITE_CONFIG_MULTITHREAD]] <dt>SQLITE_CONFIG_MULTITHREAD</dt>
  1663 ** <dd>There are no arguments to this option.  ^This option sets the
  1664 ** [threading mode] to Multi-thread.  In other words, it disables
  1665 ** mutexing on [database connection] and [prepared statement] objects.
  1666 ** The application is responsible for serializing access to
  1667 ** [database connections] and [prepared statements].  But other mutexes
  1668 ** are enabled so that SQLite will be safe to use in a multi-threaded
  1669 ** environment as long as no two threads attempt to use the same
  1670 ** [database connection] at the same time.  ^If SQLite is compiled with
  1671 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1672 ** it is not possible to set the Multi-thread [threading mode] and
  1673 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
  1674 ** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>
  1675 **
  1676 ** [[SQLITE_CONFIG_SERIALIZED]] <dt>SQLITE_CONFIG_SERIALIZED</dt>
  1677 ** <dd>There are no arguments to this option.  ^This option sets the
  1678 ** [threading mode] to Serialized. In other words, this option enables
  1679 ** all mutexes including the recursive
  1680 ** mutexes on [database connection] and [prepared statement] objects.
  1681 ** In this mode (which is the default when SQLite is compiled with
  1682 ** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
  1683 ** to [database connections] and [prepared statements] so that the
  1684 ** application is free to use the same [database connection] or the
  1685 ** same [prepared statement] in different threads at the same time.
  1686 ** ^If SQLite is compiled with
  1687 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1688 ** it is not possible to set the Serialized [threading mode] and
  1689 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
  1690 ** SQLITE_CONFIG_SERIALIZED configuration option.</dd>
  1691 **
  1692 ** [[SQLITE_CONFIG_MALLOC]] <dt>SQLITE_CONFIG_MALLOC</dt>
  1693 ** <dd> ^(The SQLITE_CONFIG_MALLOC option takes a single argument which is 
  1694 ** a pointer to an instance of the [sqlite3_mem_methods] structure.
  1695 ** The argument specifies
  1696 ** alternative low-level memory allocation routines to be used in place of
  1697 ** the memory allocation routines built into SQLite.)^ ^SQLite makes
  1698 ** its own private copy of the content of the [sqlite3_mem_methods] structure
  1699 ** before the [sqlite3_config()] call returns.</dd>
  1700 **
  1701 ** [[SQLITE_CONFIG_GETMALLOC]] <dt>SQLITE_CONFIG_GETMALLOC</dt>
  1702 ** <dd> ^(The SQLITE_CONFIG_GETMALLOC option takes a single argument which
  1703 ** is a pointer to an instance of the [sqlite3_mem_methods] structure.
  1704 ** The [sqlite3_mem_methods]
  1705 ** structure is filled with the currently defined memory allocation routines.)^
  1706 ** This option can be used to overload the default memory allocation
  1707 ** routines with a wrapper that simulations memory allocation failure or
  1708 ** tracks memory usage, for example. </dd>
  1709 **
  1710 ** [[SQLITE_CONFIG_SMALL_MALLOC]] <dt>SQLITE_CONFIG_SMALL_MALLOC</dt>
  1711 ** <dd> ^The SQLITE_CONFIG_SMALL_MALLOC option takes single argument of
  1712 ** type int, interpreted as a boolean, which if true provides a hint to
  1713 ** SQLite that it should avoid large memory allocations if possible.
  1714 ** SQLite will run faster if it is free to make large memory allocations,
  1715 ** but some application might prefer to run slower in exchange for
  1716 ** guarantees about memory fragmentation that are possible if large
  1717 ** allocations are avoided.  This hint is normally off.
  1718 ** </dd>
  1719 **
  1720 ** [[SQLITE_CONFIG_MEMSTATUS]] <dt>SQLITE_CONFIG_MEMSTATUS</dt>
  1721 ** <dd> ^The SQLITE_CONFIG_MEMSTATUS option takes single argument of type int,
  1722 ** interpreted as a boolean, which enables or disables the collection of
  1723 ** memory allocation statistics. ^(When memory allocation statistics are
  1724 ** disabled, the following SQLite interfaces become non-operational:
  1725 **   <ul>
  1726 **   <li> [sqlite3_memory_used()]
  1727 **   <li> [sqlite3_memory_highwater()]
  1728 **   <li> [sqlite3_soft_heap_limit64()]
  1729 **   <li> [sqlite3_status64()]
  1730 **   </ul>)^
  1731 ** ^Memory allocation statistics are enabled by default unless SQLite is
  1732 ** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
  1733 ** allocation statistics are disabled by default.
  1734 ** </dd>
  1735 **
  1736 ** [[SQLITE_CONFIG_SCRATCH]] <dt>SQLITE_CONFIG_SCRATCH</dt>
  1737 ** <dd> The SQLITE_CONFIG_SCRATCH option is no longer used.
  1738 ** </dd>
  1739 **
  1740 ** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
  1741 ** <dd> ^The SQLITE_CONFIG_PAGECACHE option specifies a memory pool
  1742 ** that SQLite can use for the database page cache with the default page
  1743 ** cache implementation.  
  1744 ** This configuration option is a no-op if an application-define page
  1745 ** cache implementation is loaded using the [SQLITE_CONFIG_PCACHE2].
  1746 ** ^There are three arguments to SQLITE_CONFIG_PAGECACHE: A pointer to
  1747 ** 8-byte aligned memory (pMem), the size of each page cache line (sz),
  1748 ** and the number of cache lines (N).
  1749 ** The sz argument should be the size of the largest database page
  1750 ** (a power of two between 512 and 65536) plus some extra bytes for each
  1751 ** page header.  ^The number of extra bytes needed by the page header
  1752 ** can be determined using [SQLITE_CONFIG_PCACHE_HDRSZ].
  1753 ** ^It is harmless, apart from the wasted memory,
  1754 ** for the sz parameter to be larger than necessary.  The pMem
  1755 ** argument must be either a NULL pointer or a pointer to an 8-byte
  1756 ** aligned block of memory of at least sz*N bytes, otherwise
  1757 ** subsequent behavior is undefined.
  1758 ** ^When pMem is not NULL, SQLite will strive to use the memory provided
  1759 ** to satisfy page cache needs, falling back to [sqlite3_malloc()] if
  1760 ** a page cache line is larger than sz bytes or if all of the pMem buffer
  1761 ** is exhausted.
  1762 ** ^If pMem is NULL and N is non-zero, then each database connection
  1763 ** does an initial bulk allocation for page cache memory
  1764 ** from [sqlite3_malloc()] sufficient for N cache lines if N is positive or
  1765 ** of -1024*N bytes if N is negative, . ^If additional
  1766 ** page cache memory is needed beyond what is provided by the initial
  1767 ** allocation, then SQLite goes to [sqlite3_malloc()] separately for each
  1768 ** additional cache line. </dd>
  1769 **
  1770 ** [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt>
  1771 ** <dd> ^The SQLITE_CONFIG_HEAP option specifies a static memory buffer 
  1772 ** that SQLite will use for all of its dynamic memory allocation needs
  1773 ** beyond those provided for by [SQLITE_CONFIG_PAGECACHE].
  1774 ** ^The SQLITE_CONFIG_HEAP option is only available if SQLite is compiled
  1775 ** with either [SQLITE_ENABLE_MEMSYS3] or [SQLITE_ENABLE_MEMSYS5] and returns
  1776 ** [SQLITE_ERROR] if invoked otherwise.
  1777 ** ^There are three arguments to SQLITE_CONFIG_HEAP:
  1778 ** An 8-byte aligned pointer to the memory,
  1779 ** the number of bytes in the memory buffer, and the minimum allocation size.
  1780 ** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
  1781 ** to using its default memory allocator (the system malloc() implementation),
  1782 ** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
  1783 ** memory pointer is not NULL then the alternative memory
  1784 ** allocator is engaged to handle all of SQLites memory allocation needs.
  1785 ** The first pointer (the memory pointer) must be aligned to an 8-byte
  1786 ** boundary or subsequent behavior of SQLite will be undefined.
  1787 ** The minimum allocation size is capped at 2**12. Reasonable values
  1788 ** for the minimum allocation size are 2**5 through 2**8.</dd>
  1789 **
  1790 ** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
  1791 ** <dd> ^(The SQLITE_CONFIG_MUTEX option takes a single argument which is a
  1792 ** pointer to an instance of the [sqlite3_mutex_methods] structure.
  1793 ** The argument specifies alternative low-level mutex routines to be used
  1794 ** in place the mutex routines built into SQLite.)^  ^SQLite makes a copy of
  1795 ** the content of the [sqlite3_mutex_methods] structure before the call to
  1796 ** [sqlite3_config()] returns. ^If SQLite is compiled with
  1797 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1798 ** the entire mutexing subsystem is omitted from the build and hence calls to
  1799 ** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
  1800 ** return [SQLITE_ERROR].</dd>
  1801 **
  1802 ** [[SQLITE_CONFIG_GETMUTEX]] <dt>SQLITE_CONFIG_GETMUTEX</dt>
  1803 ** <dd> ^(The SQLITE_CONFIG_GETMUTEX option takes a single argument which
  1804 ** is a pointer to an instance of the [sqlite3_mutex_methods] structure.  The
  1805 ** [sqlite3_mutex_methods]
  1806 ** structure is filled with the currently defined mutex routines.)^
  1807 ** This option can be used to overload the default mutex allocation
  1808 ** routines with a wrapper used to track mutex usage for performance
  1809 ** profiling or testing, for example.   ^If SQLite is compiled with
  1810 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1811 ** the entire mutexing subsystem is omitted from the build and hence calls to
  1812 ** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will
  1813 ** return [SQLITE_ERROR].</dd>
  1814 **
  1815 ** [[SQLITE_CONFIG_LOOKASIDE]] <dt>SQLITE_CONFIG_LOOKASIDE</dt>
  1816 ** <dd> ^(The SQLITE_CONFIG_LOOKASIDE option takes two arguments that determine
  1817 ** the default size of lookaside memory on each [database connection].
  1818 ** The first argument is the
  1819 ** size of each lookaside buffer slot and the second is the number of
  1820 ** slots allocated to each database connection.)^  ^(SQLITE_CONFIG_LOOKASIDE
  1821 ** sets the <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]
  1822 ** option to [sqlite3_db_config()] can be used to change the lookaside
  1823 ** configuration on individual connections.)^ </dd>
  1824 **
  1825 ** [[SQLITE_CONFIG_PCACHE2]] <dt>SQLITE_CONFIG_PCACHE2</dt>
  1826 ** <dd> ^(The SQLITE_CONFIG_PCACHE2 option takes a single argument which is 
  1827 ** a pointer to an [sqlite3_pcache_methods2] object.  This object specifies
  1828 ** the interface to a custom page cache implementation.)^
  1829 ** ^SQLite makes a copy of the [sqlite3_pcache_methods2] object.</dd>
  1830 **
  1831 ** [[SQLITE_CONFIG_GETPCACHE2]] <dt>SQLITE_CONFIG_GETPCACHE2</dt>
  1832 ** <dd> ^(The SQLITE_CONFIG_GETPCACHE2 option takes a single argument which
  1833 ** is a pointer to an [sqlite3_pcache_methods2] object.  SQLite copies of
  1834 ** the current page cache implementation into that object.)^ </dd>
  1835 **
  1836 ** [[SQLITE_CONFIG_LOG]] <dt>SQLITE_CONFIG_LOG</dt>
  1837 ** <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite
  1838 ** global [error log].
  1839 ** (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
  1840 ** function with a call signature of void(*)(void*,int,const char*), 
  1841 ** and a pointer to void. ^If the function pointer is not NULL, it is
  1842 ** invoked by [sqlite3_log()] to process each logging event.  ^If the
  1843 ** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
  1844 ** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
  1845 ** passed through as the first parameter to the application-defined logger
  1846 ** function whenever that function is invoked.  ^The second parameter to
  1847 ** the logger function is a copy of the first parameter to the corresponding
  1848 ** [sqlite3_log()] call and is intended to be a [result code] or an
  1849 ** [extended result code].  ^The third parameter passed to the logger is
  1850 ** log message after formatting via [sqlite3_snprintf()].
  1851 ** The SQLite logging interface is not reentrant; the logger function
  1852 ** supplied by the application must not invoke any SQLite interface.
  1853 ** In a multi-threaded application, the application-defined logger
  1854 ** function must be threadsafe. </dd>
  1855 **
  1856 ** [[SQLITE_CONFIG_URI]] <dt>SQLITE_CONFIG_URI
  1857 ** <dd>^(The SQLITE_CONFIG_URI option takes a single argument of type int.
  1858 ** If non-zero, then URI handling is globally enabled. If the parameter is zero,
  1859 ** then URI handling is globally disabled.)^ ^If URI handling is globally
  1860 ** enabled, all filenames passed to [sqlite3_open()], [sqlite3_open_v2()],
  1861 ** [sqlite3_open16()] or
  1862 ** specified as part of [ATTACH] commands are interpreted as URIs, regardless
  1863 ** of whether or not the [SQLITE_OPEN_URI] flag is set when the database
  1864 ** connection is opened. ^If it is globally disabled, filenames are
  1865 ** only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the
  1866 ** database connection is opened. ^(By default, URI handling is globally
  1867 ** disabled. The default value may be changed by compiling with the
  1868 ** [SQLITE_USE_URI] symbol defined.)^
  1869 **
  1870 ** [[SQLITE_CONFIG_COVERING_INDEX_SCAN]] <dt>SQLITE_CONFIG_COVERING_INDEX_SCAN
  1871 ** <dd>^The SQLITE_CONFIG_COVERING_INDEX_SCAN option takes a single integer
  1872 ** argument which is interpreted as a boolean in order to enable or disable
  1873 ** the use of covering indices for full table scans in the query optimizer.
  1874 ** ^The default setting is determined
  1875 ** by the [SQLITE_ALLOW_COVERING_INDEX_SCAN] compile-time option, or is "on"
  1876 ** if that compile-time option is omitted.
  1877 ** The ability to disable the use of covering indices for full table scans
  1878 ** is because some incorrectly coded legacy applications might malfunction
  1879 ** when the optimization is enabled.  Providing the ability to
  1880 ** disable the optimization allows the older, buggy application code to work
  1881 ** without change even with newer versions of SQLite.
  1882 **
  1883 ** [[SQLITE_CONFIG_PCACHE]] [[SQLITE_CONFIG_GETPCACHE]]
  1884 ** <dt>SQLITE_CONFIG_PCACHE and SQLITE_CONFIG_GETPCACHE
  1885 ** <dd> These options are obsolete and should not be used by new code.
  1886 ** They are retained for backwards compatibility but are now no-ops.
  1887 ** </dd>
  1888 **
  1889 ** [[SQLITE_CONFIG_SQLLOG]]
  1890 ** <dt>SQLITE_CONFIG_SQLLOG
  1891 ** <dd>This option is only available if sqlite is compiled with the
  1892 ** [SQLITE_ENABLE_SQLLOG] pre-processor macro defined. The first argument should
  1893 ** be a pointer to a function of type void(*)(void*,sqlite3*,const char*, int).
  1894 ** The second should be of type (void*). The callback is invoked by the library
  1895 ** in three separate circumstances, identified by the value passed as the
  1896 ** fourth parameter. If the fourth parameter is 0, then the database connection
  1897 ** passed as the second argument has just been opened. The third argument
  1898 ** points to a buffer containing the name of the main database file. If the
  1899 ** fourth parameter is 1, then the SQL statement that the third parameter
  1900 ** points to has just been executed. Or, if the fourth parameter is 2, then
  1901 ** the connection being passed as the second parameter is being closed. The
  1902 ** third parameter is passed NULL In this case.  An example of using this
  1903 ** configuration option can be seen in the "test_sqllog.c" source file in
  1904 ** the canonical SQLite source tree.</dd>
  1905 **
  1906 ** [[SQLITE_CONFIG_MMAP_SIZE]]
  1907 ** <dt>SQLITE_CONFIG_MMAP_SIZE
  1908 ** <dd>^SQLITE_CONFIG_MMAP_SIZE takes two 64-bit integer (sqlite3_int64) values
  1909 ** that are the default mmap size limit (the default setting for
  1910 ** [PRAGMA mmap_size]) and the maximum allowed mmap size limit.
  1911 ** ^The default setting can be overridden by each database connection using
  1912 ** either the [PRAGMA mmap_size] command, or by using the
  1913 ** [SQLITE_FCNTL_MMAP_SIZE] file control.  ^(The maximum allowed mmap size
  1914 ** will be silently truncated if necessary so that it does not exceed the
  1915 ** compile-time maximum mmap size set by the
  1916 ** [SQLITE_MAX_MMAP_SIZE] compile-time option.)^
  1917 ** ^If either argument to this option is negative, then that argument is
  1918 ** changed to its compile-time default.
  1919 **
  1920 ** [[SQLITE_CONFIG_WIN32_HEAPSIZE]]
  1921 ** <dt>SQLITE_CONFIG_WIN32_HEAPSIZE
  1922 ** <dd>^The SQLITE_CONFIG_WIN32_HEAPSIZE option is only available if SQLite is
  1923 ** compiled for Windows with the [SQLITE_WIN32_MALLOC] pre-processor macro
  1924 ** defined. ^SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value
  1925 ** that specifies the maximum size of the created heap.
  1926 **
  1927 ** [[SQLITE_CONFIG_PCACHE_HDRSZ]]
  1928 ** <dt>SQLITE_CONFIG_PCACHE_HDRSZ
  1929 ** <dd>^The SQLITE_CONFIG_PCACHE_HDRSZ option takes a single parameter which
  1930 ** is a pointer to an integer and writes into that integer the number of extra
  1931 ** bytes per page required for each page in [SQLITE_CONFIG_PAGECACHE].
  1932 ** The amount of extra space required can change depending on the compiler,
  1933 ** target platform, and SQLite version.
  1934 **
  1935 ** [[SQLITE_CONFIG_PMASZ]]
  1936 ** <dt>SQLITE_CONFIG_PMASZ
  1937 ** <dd>^The SQLITE_CONFIG_PMASZ option takes a single parameter which
  1938 ** is an unsigned integer and sets the "Minimum PMA Size" for the multithreaded
  1939 ** sorter to that integer.  The default minimum PMA Size is set by the
  1940 ** [SQLITE_SORTER_PMASZ] compile-time option.  New threads are launched
  1941 ** to help with sort operations when multithreaded sorting
  1942 ** is enabled (using the [PRAGMA threads] command) and the amount of content
  1943 ** to be sorted exceeds the page size times the minimum of the
  1944 ** [PRAGMA cache_size] setting and this value.
  1945 **
  1946 ** [[SQLITE_CONFIG_STMTJRNL_SPILL]]
  1947 ** <dt>SQLITE_CONFIG_STMTJRNL_SPILL
  1948 ** <dd>^The SQLITE_CONFIG_STMTJRNL_SPILL option takes a single parameter which
  1949 ** becomes the [statement journal] spill-to-disk threshold.  
  1950 ** [Statement journals] are held in memory until their size (in bytes)
  1951 ** exceeds this threshold, at which point they are written to disk.
  1952 ** Or if the threshold is -1, statement journals are always held
  1953 ** exclusively in memory.
  1954 ** Since many statement journals never become large, setting the spill
  1955 ** threshold to a value such as 64KiB can greatly reduce the amount of
  1956 ** I/O required to support statement rollback.
  1957 ** The default value for this setting is controlled by the
  1958 ** [SQLITE_STMTJRNL_SPILL] compile-time option.
  1959 **
  1960 ** [[SQLITE_CONFIG_SORTERREF_SIZE]]
  1961 ** <dt>SQLITE_CONFIG_SORTERREF_SIZE
  1962 ** <dd>The SQLITE_CONFIG_SORTERREF_SIZE option accepts a single parameter
  1963 ** of type (int) - the new value of the sorter-reference size threshold.
  1964 ** Usually, when SQLite uses an external sort to order records according
  1965 ** to an ORDER BY clause, all fields required by the caller are present in the
  1966 ** sorted records. However, if SQLite determines based on the declared type
  1967 ** of a table column that its values are likely to be very large - larger
  1968 ** than the configured sorter-reference size threshold - then a reference
  1969 ** is stored in each sorted record and the required column values loaded
  1970 ** from the database as records are returned in sorted order. The default
  1971 ** value for this option is to never use this optimization. Specifying a 
  1972 ** negative value for this option restores the default behaviour.
  1973 ** This option is only available if SQLite is compiled with the
  1974 ** [SQLITE_ENABLE_SORTER_REFERENCES] compile-time option.
  1975 ** </dl>
  1976 */
  1977 #define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
  1978 #define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
  1979 #define SQLITE_CONFIG_SERIALIZED    3  /* nil */
  1980 #define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
  1981 #define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
  1982 #define SQLITE_CONFIG_SCRATCH       6  /* No longer used */
  1983 #define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
  1984 #define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
  1985 #define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
  1986 #define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
  1987 #define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
  1988 /* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 
  1989 #define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
  1990 #define SQLITE_CONFIG_PCACHE       14  /* no-op */
  1991 #define SQLITE_CONFIG_GETPCACHE    15  /* no-op */
  1992 #define SQLITE_CONFIG_LOG          16  /* xFunc, void* */
  1993 #define SQLITE_CONFIG_URI          17  /* int */
  1994 #define SQLITE_CONFIG_PCACHE2      18  /* sqlite3_pcache_methods2* */
  1995 #define SQLITE_CONFIG_GETPCACHE2   19  /* sqlite3_pcache_methods2* */
  1996 #define SQLITE_CONFIG_COVERING_INDEX_SCAN 20  /* int */
  1997 #define SQLITE_CONFIG_SQLLOG       21  /* xSqllog, void* */
  1998 #define SQLITE_CONFIG_MMAP_SIZE    22  /* sqlite3_int64, sqlite3_int64 */
  1999 #define SQLITE_CONFIG_WIN32_HEAPSIZE      23  /* int nByte */
  2000 #define SQLITE_CONFIG_PCACHE_HDRSZ        24  /* int *psz */
  2001 #define SQLITE_CONFIG_PMASZ               25  /* unsigned int szPma */
  2002 #define SQLITE_CONFIG_STMTJRNL_SPILL      26  /* int nByte */
  2003 #define SQLITE_CONFIG_SMALL_MALLOC        27  /* boolean */
  2004 #define SQLITE_CONFIG_SORTERREF_SIZE      28  /* int nByte */
  2005 
  2006 /*
  2007 ** CAPI3REF: Database Connection Configuration Options
  2008 **
  2009 ** These constants are the available integer configuration options that
  2010 ** can be passed as the second argument to the [sqlite3_db_config()] interface.
  2011 **
  2012 ** New configuration options may be added in future releases of SQLite.
  2013 ** Existing configuration options might be discontinued.  Applications
  2014 ** should check the return code from [sqlite3_db_config()] to make sure that
  2015 ** the call worked.  ^The [sqlite3_db_config()] interface will return a
  2016 ** non-zero [error code] if a discontinued or unsupported configuration option
  2017 ** is invoked.
  2018 **
  2019 ** <dl>
  2020 ** [[SQLITE_DBCONFIG_LOOKASIDE]]
  2021 ** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
  2022 ** <dd> ^This option takes three additional arguments that determine the 
  2023 ** [lookaside memory allocator] configuration for the [database connection].
  2024 ** ^The first argument (the third parameter to [sqlite3_db_config()] is a
  2025 ** pointer to a memory buffer to use for lookaside memory.
  2026 ** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
  2027 ** may be NULL in which case SQLite will allocate the
  2028 ** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
  2029 ** size of each lookaside buffer slot.  ^The third argument is the number of
  2030 ** slots.  The size of the buffer in the first argument must be greater than
  2031 ** or equal to the product of the second and third arguments.  The buffer
  2032 ** must be aligned to an 8-byte boundary.  ^If the second argument to
  2033 ** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally
  2034 ** rounded down to the next smaller multiple of 8.  ^(The lookaside memory
  2035 ** configuration for a database connection can only be changed when that
  2036 ** connection is not currently using lookaside memory, or in other words
  2037 ** when the "current value" returned by
  2038 ** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
  2039 ** Any attempt to change the lookaside memory configuration when lookaside
  2040 ** memory is in use leaves the configuration unchanged and returns 
  2041 ** [SQLITE_BUSY].)^</dd>
  2042 **
  2043 ** [[SQLITE_DBCONFIG_ENABLE_FKEY]]
  2044 ** <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>
  2045 ** <dd> ^This option is used to enable or disable the enforcement of
  2046 ** [foreign key constraints].  There should be two additional arguments.
  2047 ** The first argument is an integer which is 0 to disable FK enforcement,
  2048 ** positive to enable FK enforcement or negative to leave FK enforcement
  2049 ** unchanged.  The second parameter is a pointer to an integer into which
  2050 ** is written 0 or 1 to indicate whether FK enforcement is off or on
  2051 ** following this call.  The second parameter may be a NULL pointer, in
  2052 ** which case the FK enforcement setting is not reported back. </dd>
  2053 **
  2054 ** [[SQLITE_DBCONFIG_ENABLE_TRIGGER]]
  2055 ** <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>
  2056 ** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
  2057 ** There should be two additional arguments.
  2058 ** The first argument is an integer which is 0 to disable triggers,
  2059 ** positive to enable triggers or negative to leave the setting unchanged.
  2060 ** The second parameter is a pointer to an integer into which
  2061 ** is written 0 or 1 to indicate whether triggers are disabled or enabled
  2062 ** following this call.  The second parameter may be a NULL pointer, in
  2063 ** which case the trigger setting is not reported back. </dd>
  2064 **
  2065 ** [[SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER]]
  2066 ** <dt>SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER</dt>
  2067 ** <dd> ^This option is used to enable or disable the two-argument
  2068 ** version of the [fts3_tokenizer()] function which is part of the
  2069 ** [FTS3] full-text search engine extension.
  2070 ** There should be two additional arguments.
  2071 ** The first argument is an integer which is 0 to disable fts3_tokenizer() or
  2072 ** positive to enable fts3_tokenizer() or negative to leave the setting
  2073 ** unchanged.
  2074 ** The second parameter is a pointer to an integer into which
  2075 ** is written 0 or 1 to indicate whether fts3_tokenizer is disabled or enabled
  2076 ** following this call.  The second parameter may be a NULL pointer, in
  2077 ** which case the new setting is not reported back. </dd>
  2078 **
  2079 ** [[SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION]]
  2080 ** <dt>SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION</dt>
  2081 ** <dd> ^This option is used to enable or disable the [sqlite3_load_extension()]
  2082 ** interface independently of the [load_extension()] SQL function.
  2083 ** The [sqlite3_enable_load_extension()] API enables or disables both the
  2084 ** C-API [sqlite3_load_extension()] and the SQL function [load_extension()].
  2085 ** There should be two additional arguments.
  2086 ** When the first argument to this interface is 1, then only the C-API is
  2087 ** enabled and the SQL function remains disabled.  If the first argument to
  2088 ** this interface is 0, then both the C-API and the SQL function are disabled.
  2089 ** If the first argument is -1, then no changes are made to state of either the
  2090 ** C-API or the SQL function.
  2091 ** The second parameter is a pointer to an integer into which
  2092 ** is written 0 or 1 to indicate whether [sqlite3_load_extension()] interface
  2093 ** is disabled or enabled following this call.  The second parameter may
  2094 ** be a NULL pointer, in which case the new setting is not reported back.
  2095 ** </dd>
  2096 **
  2097 ** [[SQLITE_DBCONFIG_MAINDBNAME]] <dt>SQLITE_DBCONFIG_MAINDBNAME</dt>
  2098 ** <dd> ^This option is used to change the name of the "main" database
  2099 ** schema.  ^The sole argument is a pointer to a constant UTF8 string
  2100 ** which will become the new schema name in place of "main".  ^SQLite
  2101 ** does not make a copy of the new main schema name string, so the application
  2102 ** must ensure that the argument passed into this DBCONFIG option is unchanged
  2103 ** until after the database connection closes.
  2104 ** </dd>
  2105 **
  2106 ** [[SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE]] 
  2107 ** <dt>SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE</dt>
  2108 ** <dd> Usually, when a database in wal mode is closed or detached from a 
  2109 ** database handle, SQLite checks if this will mean that there are now no 
  2110 ** connections at all to the database. If so, it performs a checkpoint 
  2111 ** operation before closing the connection. This option may be used to
  2112 ** override this behaviour. The first parameter passed to this operation
  2113 ** is an integer - positive to disable checkpoints-on-close, or zero (the
  2114 ** default) to enable them, and negative to leave the setting unchanged.
  2115 ** The second parameter is a pointer to an integer
  2116 ** into which is written 0 or 1 to indicate whether checkpoints-on-close
  2117 ** have been disabled - 0 if they are not disabled, 1 if they are.
  2118 ** </dd>
  2119 **
  2120 ** [[SQLITE_DBCONFIG_ENABLE_QPSG]] <dt>SQLITE_DBCONFIG_ENABLE_QPSG</dt>
  2121 ** <dd>^(The SQLITE_DBCONFIG_ENABLE_QPSG option activates or deactivates
  2122 ** the [query planner stability guarantee] (QPSG).  When the QPSG is active,
  2123 ** a single SQL query statement will always use the same algorithm regardless
  2124 ** of values of [bound parameters].)^ The QPSG disables some query optimizations
  2125 ** that look at the values of bound parameters, which can make some queries
  2126 ** slower.  But the QPSG has the advantage of more predictable behavior.  With
  2127 ** the QPSG active, SQLite will always use the same query plan in the field as
  2128 ** was used during testing in the lab.
  2129 ** The first argument to this setting is an integer which is 0 to disable 
  2130 ** the QPSG, positive to enable QPSG, or negative to leave the setting
  2131 ** unchanged. The second parameter is a pointer to an integer into which
  2132 ** is written 0 or 1 to indicate whether the QPSG is disabled or enabled
  2133 ** following this call.
  2134 ** </dd>
  2135 **
  2136 ** [[SQLITE_DBCONFIG_TRIGGER_EQP]] <dt>SQLITE_DBCONFIG_TRIGGER_EQP</dt>
  2137 ** <dd> By default, the output of EXPLAIN QUERY PLAN commands does not 
  2138 ** include output for any operations performed by trigger programs. This
  2139 ** option is used to set or clear (the default) a flag that governs this
  2140 ** behavior. The first parameter passed to this operation is an integer -
  2141 ** positive to enable output for trigger programs, or zero to disable it,
  2142 ** or negative to leave the setting unchanged.
  2143 ** The second parameter is a pointer to an integer into which is written 
  2144 ** 0 or 1 to indicate whether output-for-triggers has been disabled - 0 if 
  2145 ** it is not disabled, 1 if it is.  
  2146 ** </dd>
  2147 **
  2148 ** [[SQLITE_DBCONFIG_RESET_DATABASE]] <dt>SQLITE_DBCONFIG_RESET_DATABASE</dt>
  2149 ** <dd> Set the SQLITE_DBCONFIG_RESET_DATABASE flag and then run
  2150 ** [VACUUM] in order to reset a database back to an empty database
  2151 ** with no schema and no content. The following process works even for
  2152 ** a badly corrupted database file:
  2153 ** <ol>
  2154 ** <li> If the database connection is newly opened, make sure it has read the
  2155 **      database schema by preparing then discarding some query against the
  2156 **      database, or calling sqlite3_table_column_metadata(), ignoring any
  2157 **      errors.  This step is only necessary if the application desires to keep
  2158 **      the database in WAL mode after the reset if it was in WAL mode before
  2159 **      the reset.  
  2160 ** <li> sqlite3_db_config(db, SQLITE_DBCONFIG_RESET_DATABASE, 1, 0);
  2161 ** <li> [sqlite3_exec](db, "[VACUUM]", 0, 0, 0);
  2162 ** <li> sqlite3_db_config(db, SQLITE_DBCONFIG_RESET_DATABASE, 0, 0);
  2163 ** </ol>
  2164 ** Because resetting a database is destructive and irreversible, the
  2165 ** process requires the use of this obscure API and multiple steps to help
  2166 ** ensure that it does not happen by accident.
  2167 **
  2168 ** [[SQLITE_DBCONFIG_DEFENSIVE]] <dt>SQLITE_DBCONFIG_DEFENSIVE</dt>
  2169 ** <dd>The SQLITE_DBCONFIG_DEFENSIVE option activates or deactivates the
  2170 ** "defensive" flag for a database connection.  When the defensive
  2171 ** flag is enabled, language features that allow ordinary SQL to 
  2172 ** deliberately corrupt the database file are disabled.  The disabled
  2173 ** features include but are not limited to the following:
  2174 ** <ul>
  2175 ** <li> The [PRAGMA writable_schema=ON] statement.
  2176 ** <li> Writes to the [sqlite_dbpage] virtual table.
  2177 ** <li> Direct writes to [shadow tables].
  2178 ** </ul>
  2179 ** </dd>
  2180 ** </dl>
  2181 */
  2182 #define SQLITE_DBCONFIG_MAINDBNAME            1000 /* const char* */
  2183 #define SQLITE_DBCONFIG_LOOKASIDE             1001 /* void* int int */
  2184 #define SQLITE_DBCONFIG_ENABLE_FKEY           1002 /* int int* */
  2185 #define SQLITE_DBCONFIG_ENABLE_TRIGGER        1003 /* int int* */
  2186 #define SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER 1004 /* int int* */
  2187 #define SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION 1005 /* int int* */
  2188 #define SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE      1006 /* int int* */
  2189 #define SQLITE_DBCONFIG_ENABLE_QPSG           1007 /* int int* */
  2190 #define SQLITE_DBCONFIG_TRIGGER_EQP           1008 /* int int* */
  2191 #define SQLITE_DBCONFIG_RESET_DATABASE        1009 /* int int* */
  2192 #define SQLITE_DBCONFIG_DEFENSIVE             1010 /* int int* */
  2193 #define SQLITE_DBCONFIG_MAX                   1010 /* Largest DBCONFIG */
  2194 
  2195 /*
  2196 ** CAPI3REF: Enable Or Disable Extended Result Codes
  2197 ** METHOD: sqlite3
  2198 **
  2199 ** ^The sqlite3_extended_result_codes() routine enables or disables the
  2200 ** [extended result codes] feature of SQLite. ^The extended result
  2201 ** codes are disabled by default for historical compatibility.
  2202 */
  2203 SQLITE_API int sqlite3_extended_result_codes(sqlite3*, int onoff);
  2204 
  2205 /*
  2206 ** CAPI3REF: Last Insert Rowid
  2207 ** METHOD: sqlite3
  2208 **
  2209 ** ^Each entry in most SQLite tables (except for [WITHOUT ROWID] tables)
  2210 ** has a unique 64-bit signed
  2211 ** integer key called the [ROWID | "rowid"]. ^The rowid is always available
  2212 ** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
  2213 ** names are not also used by explicitly declared columns. ^If
  2214 ** the table has a column of type [INTEGER PRIMARY KEY] then that column
  2215 ** is another alias for the rowid.
  2216 **
  2217 ** ^The sqlite3_last_insert_rowid(D) interface usually returns the [rowid] of
  2218 ** the most recent successful [INSERT] into a rowid table or [virtual table]
  2219 ** on database connection D. ^Inserts into [WITHOUT ROWID] tables are not
  2220 ** recorded. ^If no successful [INSERT]s into rowid tables have ever occurred 
  2221 ** on the database connection D, then sqlite3_last_insert_rowid(D) returns 
  2222 ** zero.
  2223 **
  2224 ** As well as being set automatically as rows are inserted into database
  2225 ** tables, the value returned by this function may be set explicitly by
  2226 ** [sqlite3_set_last_insert_rowid()]
  2227 **
  2228 ** Some virtual table implementations may INSERT rows into rowid tables as
  2229 ** part of committing a transaction (e.g. to flush data accumulated in memory
  2230 ** to disk). In this case subsequent calls to this function return the rowid
  2231 ** associated with these internal INSERT operations, which leads to 
  2232 ** unintuitive results. Virtual table implementations that do write to rowid
  2233 ** tables in this way can avoid this problem by restoring the original 
  2234 ** rowid value using [sqlite3_set_last_insert_rowid()] before returning 
  2235 ** control to the user.
  2236 **
  2237 ** ^(If an [INSERT] occurs within a trigger then this routine will 
  2238 ** return the [rowid] of the inserted row as long as the trigger is 
  2239 ** running. Once the trigger program ends, the value returned 
  2240 ** by this routine reverts to what it was before the trigger was fired.)^
  2241 **
  2242 ** ^An [INSERT] that fails due to a constraint violation is not a
  2243 ** successful [INSERT] and does not change the value returned by this
  2244 ** routine.  ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
  2245 ** and INSERT OR ABORT make no changes to the return value of this
  2246 ** routine when their insertion fails.  ^(When INSERT OR REPLACE
  2247 ** encounters a constraint violation, it does not fail.  The
  2248 ** INSERT continues to completion after deleting rows that caused
  2249 ** the constraint problem so INSERT OR REPLACE will always change
  2250 ** the return value of this interface.)^
  2251 **
  2252 ** ^For the purposes of this routine, an [INSERT] is considered to
  2253 ** be successful even if it is subsequently rolled back.
  2254 **
  2255 ** This function is accessible to SQL statements via the
  2256 ** [last_insert_rowid() SQL function].
  2257 **
  2258 ** If a separate thread performs a new [INSERT] on the same
  2259 ** database connection while the [sqlite3_last_insert_rowid()]
  2260 ** function is running and thus changes the last insert [rowid],
  2261 ** then the value returned by [sqlite3_last_insert_rowid()] is
  2262 ** unpredictable and might not equal either the old or the new
  2263 ** last insert [rowid].
  2264 */
  2265 SQLITE_API sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);
  2266 
  2267 /*
  2268 ** CAPI3REF: Set the Last Insert Rowid value.
  2269 ** METHOD: sqlite3
  2270 **
  2271 ** The sqlite3_set_last_insert_rowid(D, R) method allows the application to
  2272 ** set the value returned by calling sqlite3_last_insert_rowid(D) to R 
  2273 ** without inserting a row into the database.
  2274 */
  2275 SQLITE_API void sqlite3_set_last_insert_rowid(sqlite3*,sqlite3_int64);
  2276 
  2277 /*
  2278 ** CAPI3REF: Count The Number Of Rows Modified
  2279 ** METHOD: sqlite3
  2280 **
  2281 ** ^This function returns the number of rows modified, inserted or
  2282 ** deleted by the most recently completed INSERT, UPDATE or DELETE
  2283 ** statement on the database connection specified by the only parameter.
  2284 ** ^Executing any other type of SQL statement does not modify the value
  2285 ** returned by this function.
  2286 **
  2287 ** ^Only changes made directly by the INSERT, UPDATE or DELETE statement are
  2288 ** considered - auxiliary changes caused by [CREATE TRIGGER | triggers], 
  2289 ** [foreign key actions] or [REPLACE] constraint resolution are not counted.
  2290 ** 
  2291 ** Changes to a view that are intercepted by 
  2292 ** [INSTEAD OF trigger | INSTEAD OF triggers] are not counted. ^The value 
  2293 ** returned by sqlite3_changes() immediately after an INSERT, UPDATE or 
  2294 ** DELETE statement run on a view is always zero. Only changes made to real 
  2295 ** tables are counted.
  2296 **
  2297 ** Things are more complicated if the sqlite3_changes() function is
  2298 ** executed while a trigger program is running. This may happen if the
  2299 ** program uses the [changes() SQL function], or if some other callback
  2300 ** function invokes sqlite3_changes() directly. Essentially:
  2301 ** 
  2302 ** <ul>
  2303 **   <li> ^(Before entering a trigger program the value returned by
  2304 **        sqlite3_changes() function is saved. After the trigger program 
  2305 **        has finished, the original value is restored.)^
  2306 ** 
  2307 **   <li> ^(Within a trigger program each INSERT, UPDATE and DELETE 
  2308 **        statement sets the value returned by sqlite3_changes() 
  2309 **        upon completion as normal. Of course, this value will not include 
  2310 **        any changes performed by sub-triggers, as the sqlite3_changes() 
  2311 **        value will be saved and restored after each sub-trigger has run.)^
  2312 ** </ul>
  2313 ** 
  2314 ** ^This means that if the changes() SQL function (or similar) is used
  2315 ** by the first INSERT, UPDATE or DELETE statement within a trigger, it 
  2316 ** returns the value as set when the calling statement began executing.
  2317 ** ^If it is used by the second or subsequent such statement within a trigger 
  2318 ** program, the value returned reflects the number of rows modified by the 
  2319 ** previous INSERT, UPDATE or DELETE statement within the same trigger.
  2320 **
  2321 ** If a separate thread makes changes on the same database connection
  2322 ** while [sqlite3_changes()] is running then the value returned
  2323 ** is unpredictable and not meaningful.
  2324 **
  2325 ** See also:
  2326 ** <ul>
  2327 ** <li> the [sqlite3_total_changes()] interface
  2328 ** <li> the [count_changes pragma]
  2329 ** <li> the [changes() SQL function]
  2330 ** <li> the [data_version pragma]
  2331 ** </ul>
  2332 */
  2333 SQLITE_API int sqlite3_changes(sqlite3*);
  2334 
  2335 /*
  2336 ** CAPI3REF: Total Number Of Rows Modified
  2337 ** METHOD: sqlite3
  2338 **
  2339 ** ^This function returns the total number of rows inserted, modified or
  2340 ** deleted by all [INSERT], [UPDATE] or [DELETE] statements completed
  2341 ** since the database connection was opened, including those executed as
  2342 ** part of trigger programs. ^Executing any other type of SQL statement
  2343 ** does not affect the value returned by sqlite3_total_changes().
  2344 ** 
  2345 ** ^Changes made as part of [foreign key actions] are included in the
  2346 ** count, but those made as part of REPLACE constraint resolution are
  2347 ** not. ^Changes to a view that are intercepted by INSTEAD OF triggers 
  2348 ** are not counted.
  2349 **
  2350 ** This the [sqlite3_total_changes(D)] interface only reports the number
  2351 ** of rows that changed due to SQL statement run against database
  2352 ** connection D.  Any changes by other database connections are ignored.
  2353 ** To detect changes against a database file from other database
  2354 ** connections use the [PRAGMA data_version] command or the
  2355 ** [SQLITE_FCNTL_DATA_VERSION] [file control].
  2356 ** 
  2357 ** If a separate thread makes changes on the same database connection
  2358 ** while [sqlite3_total_changes()] is running then the value
  2359 ** returned is unpredictable and not meaningful.
  2360 **
  2361 ** See also:
  2362 ** <ul>
  2363 ** <li> the [sqlite3_changes()] interface
  2364 ** <li> the [count_changes pragma]
  2365 ** <li> the [changes() SQL function]
  2366 ** <li> the [data_version pragma]
  2367 ** <li> the [SQLITE_FCNTL_DATA_VERSION] [file control]
  2368 ** </ul>
  2369 */
  2370 SQLITE_API int sqlite3_total_changes(sqlite3*);
  2371 
  2372 /*
  2373 ** CAPI3REF: Interrupt A Long-Running Query
  2374 ** METHOD: sqlite3
  2375 **
  2376 ** ^This function causes any pending database operation to abort and
  2377 ** return at its earliest opportunity. This routine is typically
  2378 ** called in response to a user action such as pressing "Cancel"
  2379 ** or Ctrl-C where the user wants a long query operation to halt
  2380 ** immediately.
  2381 **
  2382 ** ^It is safe to call this routine from a thread different from the
  2383 ** thread that is currently running the database operation.  But it
  2384 ** is not safe to call this routine with a [database connection] that
  2385 ** is closed or might close before sqlite3_interrupt() returns.
  2386 **
  2387 ** ^If an SQL operation is very nearly finished at the time when
  2388 ** sqlite3_interrupt() is called, then it might not have an opportunity
  2389 ** to be interrupted and might continue to completion.
  2390 **
  2391 ** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
  2392 ** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
  2393 ** that is inside an explicit transaction, then the entire transaction
  2394 ** will be rolled back automatically.
  2395 **
  2396 ** ^The sqlite3_interrupt(D) call is in effect until all currently running
  2397 ** SQL statements on [database connection] D complete.  ^Any new SQL statements
  2398 ** that are started after the sqlite3_interrupt() call and before the 
  2399 ** running statements reaches zero are interrupted as if they had been
  2400 ** running prior to the sqlite3_interrupt() call.  ^New SQL statements
  2401 ** that are started after the running statement count reaches zero are
  2402 ** not effected by the sqlite3_interrupt().
  2403 ** ^A call to sqlite3_interrupt(D) that occurs when there are no running
  2404 ** SQL statements is a no-op and has no effect on SQL statements
  2405 ** that are started after the sqlite3_interrupt() call returns.
  2406 */
  2407 SQLITE_API void sqlite3_interrupt(sqlite3*);
  2408 
  2409 /*
  2410 ** CAPI3REF: Determine If An SQL Statement Is Complete
  2411 **
  2412 ** These routines are useful during command-line input to determine if the
  2413 ** currently entered text seems to form a complete SQL statement or
  2414 ** if additional input is needed before sending the text into
  2415 ** SQLite for parsing.  ^These routines return 1 if the input string
  2416 ** appears to be a complete SQL statement.  ^A statement is judged to be
  2417 ** complete if it ends with a semicolon token and is not a prefix of a
  2418 ** well-formed CREATE TRIGGER statement.  ^Semicolons that are embedded within
  2419 ** string literals or quoted identifier names or comments are not
  2420 ** independent tokens (they are part of the token in which they are
  2421 ** embedded) and thus do not count as a statement terminator.  ^Whitespace
  2422 ** and comments that follow the final semicolon are ignored.
  2423 **
  2424 ** ^These routines return 0 if the statement is incomplete.  ^If a
  2425 ** memory allocation fails, then SQLITE_NOMEM is returned.
  2426 **
  2427 ** ^These routines do not parse the SQL statements thus
  2428 ** will not detect syntactically incorrect SQL.
  2429 **
  2430 ** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior 
  2431 ** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked
  2432 ** automatically by sqlite3_complete16().  If that initialization fails,
  2433 ** then the return value from sqlite3_complete16() will be non-zero
  2434 ** regardless of whether or not the input SQL is complete.)^
  2435 **
  2436 ** The input to [sqlite3_complete()] must be a zero-terminated
  2437 ** UTF-8 string.
  2438 **
  2439 ** The input to [sqlite3_complete16()] must be a zero-terminated
  2440 ** UTF-16 string in native byte order.
  2441 */
  2442 SQLITE_API int sqlite3_complete(const char *sql);
  2443 SQLITE_API int sqlite3_complete16(const void *sql);
  2444 
  2445 /*
  2446 ** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
  2447 ** KEYWORDS: {busy-handler callback} {busy handler}
  2448 ** METHOD: sqlite3
  2449 **
  2450 ** ^The sqlite3_busy_handler(D,X,P) routine sets a callback function X
  2451 ** that might be invoked with argument P whenever
  2452 ** an attempt is made to access a database table associated with
  2453 ** [database connection] D when another thread
  2454 ** or process has the table locked.
  2455 ** The sqlite3_busy_handler() interface is used to implement
  2456 ** [sqlite3_busy_timeout()] and [PRAGMA busy_timeout].
  2457 **
  2458 ** ^If the busy callback is NULL, then [SQLITE_BUSY]
  2459 ** is returned immediately upon encountering the lock.  ^If the busy callback
  2460 ** is not NULL, then the callback might be invoked with two arguments.
  2461 **
  2462 ** ^The first argument to the busy handler is a copy of the void* pointer which
  2463 ** is the third argument to sqlite3_busy_handler().  ^The second argument to
  2464 ** the busy handler callback is the number of times that the busy handler has
  2465 ** been invoked previously for the same locking event.  ^If the
  2466 ** busy callback returns 0, then no additional attempts are made to
  2467 ** access the database and [SQLITE_BUSY] is returned
  2468 ** to the application.
  2469 ** ^If the callback returns non-zero, then another attempt
  2470 ** is made to access the database and the cycle repeats.
  2471 **
  2472 ** The presence of a busy handler does not guarantee that it will be invoked
  2473 ** when there is lock contention. ^If SQLite determines that invoking the busy
  2474 ** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
  2475 ** to the application instead of invoking the 
  2476 ** busy handler.
  2477 ** Consider a scenario where one process is holding a read lock that
  2478 ** it is trying to promote to a reserved lock and
  2479 ** a second process is holding a reserved lock that it is trying
  2480 ** to promote to an exclusive lock.  The first process cannot proceed
  2481 ** because it is blocked by the second and the second process cannot
  2482 ** proceed because it is blocked by the first.  If both processes
  2483 ** invoke the busy handlers, neither will make any progress.  Therefore,
  2484 ** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
  2485 ** will induce the first process to release its read lock and allow
  2486 ** the second process to proceed.
  2487 **
  2488 ** ^The default busy callback is NULL.
  2489 **
  2490 ** ^(There can only be a single busy handler defined for each
  2491 ** [database connection].  Setting a new busy handler clears any
  2492 ** previously set handler.)^  ^Note that calling [sqlite3_busy_timeout()]
  2493 ** or evaluating [PRAGMA busy_timeout=N] will change the
  2494 ** busy handler and thus clear any previously set busy handler.
  2495 **
  2496 ** The busy callback should not take any actions which modify the
  2497 ** database connection that invoked the busy handler.  In other words,
  2498 ** the busy handler is not reentrant.  Any such actions
  2499 ** result in undefined behavior.
  2500 ** 
  2501 ** A busy handler must not close the database connection
  2502 ** or [prepared statement] that invoked the busy handler.
  2503 */
  2504 SQLITE_API int sqlite3_busy_handler(sqlite3*,int(*)(void*,int),void*);
  2505 
  2506 /*
  2507 ** CAPI3REF: Set A Busy Timeout
  2508 ** METHOD: sqlite3
  2509 **
  2510 ** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
  2511 ** for a specified amount of time when a table is locked.  ^The handler
  2512 ** will sleep multiple times until at least "ms" milliseconds of sleeping
  2513 ** have accumulated.  ^After at least "ms" milliseconds of sleeping,
  2514 ** the handler returns 0 which causes [sqlite3_step()] to return
  2515 ** [SQLITE_BUSY].
  2516 **
  2517 ** ^Calling this routine with an argument less than or equal to zero
  2518 ** turns off all busy handlers.
  2519 **
  2520 ** ^(There can only be a single busy handler for a particular
  2521 ** [database connection] at any given moment.  If another busy handler
  2522 ** was defined  (using [sqlite3_busy_handler()]) prior to calling
  2523 ** this routine, that other busy handler is cleared.)^
  2524 **
  2525 ** See also:  [PRAGMA busy_timeout]
  2526 */
  2527 SQLITE_API int sqlite3_busy_timeout(sqlite3*, int ms);
  2528 
  2529 /*
  2530 ** CAPI3REF: Convenience Routines For Running Queries
  2531 ** METHOD: sqlite3
  2532 **
  2533 ** This is a legacy interface that is preserved for backwards compatibility.
  2534 ** Use of this interface is not recommended.
  2535 **
  2536 ** Definition: A <b>result table</b> is memory data structure created by the
  2537 ** [sqlite3_get_table()] interface.  A result table records the
  2538 ** complete query results from one or more queries.
  2539 **
  2540 ** The table conceptually has a number of rows and columns.  But
  2541 ** these numbers are not part of the result table itself.  These
  2542 ** numbers are obtained separately.  Let N be the number of rows
  2543 ** and M be the number of columns.
  2544 **
  2545 ** A result table is an array of pointers to zero-terminated UTF-8 strings.
  2546 ** There are (N+1)*M elements in the array.  The first M pointers point
  2547 ** to zero-terminated strings that  contain the names of the columns.
  2548 ** The remaining entries all point to query results.  NULL values result
  2549 ** in NULL pointers.  All other values are in their UTF-8 zero-terminated
  2550 ** string representation as returned by [sqlite3_column_text()].
  2551 **
  2552 ** A result table might consist of one or more memory allocations.
  2553 ** It is not safe to pass a result table directly to [sqlite3_free()].
  2554 ** A result table should be deallocated using [sqlite3_free_table()].
  2555 **
  2556 ** ^(As an example of the result table format, suppose a query result
  2557 ** is as follows:
  2558 **
  2559 ** <blockquote><pre>
  2560 **        Name        | Age
  2561 **        -----------------------
  2562 **        Alice       | 43
  2563 **        Bob         | 28
  2564 **        Cindy       | 21
  2565 ** </pre></blockquote>
  2566 **
  2567 ** There are two column (M==2) and three rows (N==3).  Thus the
  2568 ** result table has 8 entries.  Suppose the result table is stored
  2569 ** in an array names azResult.  Then azResult holds this content:
  2570 **
  2571 ** <blockquote><pre>
  2572 **        azResult&#91;0] = "Name";
  2573 **        azResult&#91;1] = "Age";
  2574 **        azResult&#91;2] = "Alice";
  2575 **        azResult&#91;3] = "43";
  2576 **        azResult&#91;4] = "Bob";
  2577 **        azResult&#91;5] = "28";
  2578 **        azResult&#91;6] = "Cindy";
  2579 **        azResult&#91;7] = "21";
  2580 ** </pre></blockquote>)^
  2581 **
  2582 ** ^The sqlite3_get_table() function evaluates one or more
  2583 ** semicolon-separated SQL statements in the zero-terminated UTF-8
  2584 ** string of its 2nd parameter and returns a result table to the
  2585 ** pointer given in its 3rd parameter.
  2586 **
  2587 ** After the application has finished with the result from sqlite3_get_table(),
  2588 ** it must pass the result table pointer to sqlite3_free_table() in order to
  2589 ** release the memory that was malloced.  Because of the way the
  2590 ** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
  2591 ** function must not try to call [sqlite3_free()] directly.  Only
  2592 ** [sqlite3_free_table()] is able to release the memory properly and safely.
  2593 **
  2594 ** The sqlite3_get_table() interface is implemented as a wrapper around
  2595 ** [sqlite3_exec()].  The sqlite3_get_table() routine does not have access
  2596 ** to any internal data structures of SQLite.  It uses only the public
  2597 ** interface defined here.  As a consequence, errors that occur in the
  2598 ** wrapper layer outside of the internal [sqlite3_exec()] call are not
  2599 ** reflected in subsequent calls to [sqlite3_errcode()] or
  2600 ** [sqlite3_errmsg()].
  2601 */
  2602 SQLITE_API int sqlite3_get_table(
  2603   sqlite3 *db,          /* An open database */
  2604   const char *zSql,     /* SQL to be evaluated */
  2605   char ***pazResult,    /* Results of the query */
  2606   int *pnRow,           /* Number of result rows written here */
  2607   int *pnColumn,        /* Number of result columns written here */
  2608   char **pzErrmsg       /* Error msg written here */
  2609 );
  2610 SQLITE_API void sqlite3_free_table(char **result);
  2611 
  2612 /*
  2613 ** CAPI3REF: Formatted String Printing Functions
  2614 **
  2615 ** These routines are work-alikes of the "printf()" family of functions
  2616 ** from the standard C library.
  2617 ** These routines understand most of the common formatting options from
  2618 ** the standard library printf() 
  2619 ** plus some additional non-standard formats ([%q], [%Q], [%w], and [%z]).
  2620 ** See the [built-in printf()] documentation for details.
  2621 **
  2622 ** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
  2623 ** results into memory obtained from [sqlite3_malloc64()].
  2624 ** The strings returned by these two routines should be
  2625 ** released by [sqlite3_free()].  ^Both routines return a
  2626 ** NULL pointer if [sqlite3_malloc64()] is unable to allocate enough
  2627 ** memory to hold the resulting string.
  2628 **
  2629 ** ^(The sqlite3_snprintf() routine is similar to "snprintf()" from
  2630 ** the standard C library.  The result is written into the
  2631 ** buffer supplied as the second parameter whose size is given by
  2632 ** the first parameter. Note that the order of the
  2633 ** first two parameters is reversed from snprintf().)^  This is an
  2634 ** historical accident that cannot be fixed without breaking
  2635 ** backwards compatibility.  ^(Note also that sqlite3_snprintf()
  2636 ** returns a pointer to its buffer instead of the number of
  2637 ** characters actually written into the buffer.)^  We admit that
  2638 ** the number of characters written would be a more useful return
  2639 ** value but we cannot change the implementation of sqlite3_snprintf()
  2640 ** now without breaking compatibility.
  2641 **
  2642 ** ^As long as the buffer size is greater than zero, sqlite3_snprintf()
  2643 ** guarantees that the buffer is always zero-terminated.  ^The first
  2644 ** parameter "n" is the total size of the buffer, including space for
  2645 ** the zero terminator.  So the longest string that can be completely
  2646 ** written will be n-1 characters.
  2647 **
  2648 ** ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf().
  2649 **
  2650 ** See also:  [built-in printf()], [printf() SQL function]
  2651 */
  2652 SQLITE_API char *sqlite3_mprintf(const char*,...);
  2653 SQLITE_API char *sqlite3_vmprintf(const char*, va_list);
  2654 SQLITE_API char *sqlite3_snprintf(int,char*,const char*, ...);
  2655 SQLITE_API char *sqlite3_vsnprintf(int,char*,const char*, va_list);
  2656 
  2657 /*
  2658 ** CAPI3REF: Memory Allocation Subsystem
  2659 **
  2660 ** The SQLite core uses these three routines for all of its own
  2661 ** internal memory allocation needs. "Core" in the previous sentence
  2662 ** does not include operating-system specific VFS implementation.  The
  2663 ** Windows VFS uses native malloc() and free() for some operations.
  2664 **
  2665 ** ^The sqlite3_malloc() routine returns a pointer to a block
  2666 ** of memory at least N bytes in length, where N is the parameter.
  2667 ** ^If sqlite3_malloc() is unable to obtain sufficient free
  2668 ** memory, it returns a NULL pointer.  ^If the parameter N to
  2669 ** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
  2670 ** a NULL pointer.
  2671 **
  2672 ** ^The sqlite3_malloc64(N) routine works just like
  2673 ** sqlite3_malloc(N) except that N is an unsigned 64-bit integer instead
  2674 ** of a signed 32-bit integer.
  2675 **
  2676 ** ^Calling sqlite3_free() with a pointer previously returned
  2677 ** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
  2678 ** that it might be reused.  ^The sqlite3_free() routine is
  2679 ** a no-op if is called with a NULL pointer.  Passing a NULL pointer
  2680 ** to sqlite3_free() is harmless.  After being freed, memory
  2681 ** should neither be read nor written.  Even reading previously freed
  2682 ** memory might result in a segmentation fault or other severe error.
  2683 ** Memory corruption, a segmentation fault, or other severe error
  2684 ** might result if sqlite3_free() is called with a non-NULL pointer that
  2685 ** was not obtained from sqlite3_malloc() or sqlite3_realloc().
  2686 **
  2687 ** ^The sqlite3_realloc(X,N) interface attempts to resize a
  2688 ** prior memory allocation X to be at least N bytes.
  2689 ** ^If the X parameter to sqlite3_realloc(X,N)
  2690 ** is a NULL pointer then its behavior is identical to calling
  2691 ** sqlite3_malloc(N).
  2692 ** ^If the N parameter to sqlite3_realloc(X,N) is zero or
  2693 ** negative then the behavior is exactly the same as calling
  2694 ** sqlite3_free(X).
  2695 ** ^sqlite3_realloc(X,N) returns a pointer to a memory allocation
  2696 ** of at least N bytes in size or NULL if insufficient memory is available.
  2697 ** ^If M is the size of the prior allocation, then min(N,M) bytes
  2698 ** of the prior allocation are copied into the beginning of buffer returned
  2699 ** by sqlite3_realloc(X,N) and the prior allocation is freed.
  2700 ** ^If sqlite3_realloc(X,N) returns NULL and N is positive, then the
  2701 ** prior allocation is not freed.
  2702 **
  2703 ** ^The sqlite3_realloc64(X,N) interfaces works the same as
  2704 ** sqlite3_realloc(X,N) except that N is a 64-bit unsigned integer instead
  2705 ** of a 32-bit signed integer.
  2706 **
  2707 ** ^If X is a memory allocation previously obtained from sqlite3_malloc(),
  2708 ** sqlite3_malloc64(), sqlite3_realloc(), or sqlite3_realloc64(), then
  2709 ** sqlite3_msize(X) returns the size of that memory allocation in bytes.
  2710 ** ^The value returned by sqlite3_msize(X) might be larger than the number
  2711 ** of bytes requested when X was allocated.  ^If X is a NULL pointer then
  2712 ** sqlite3_msize(X) returns zero.  If X points to something that is not
  2713 ** the beginning of memory allocation, or if it points to a formerly
  2714 ** valid memory allocation that has now been freed, then the behavior
  2715 ** of sqlite3_msize(X) is undefined and possibly harmful.
  2716 **
  2717 ** ^The memory returned by sqlite3_malloc(), sqlite3_realloc(),
  2718 ** sqlite3_malloc64(), and sqlite3_realloc64()
  2719 ** is always aligned to at least an 8 byte boundary, or to a
  2720 ** 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time
  2721 ** option is used.
  2722 **
  2723 ** In SQLite version 3.5.0 and 3.5.1, it was possible to define
  2724 ** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
  2725 ** implementation of these routines to be omitted.  That capability
  2726 ** is no longer provided.  Only built-in memory allocators can be used.
  2727 **
  2728 ** Prior to SQLite version 3.7.10, the Windows OS interface layer called
  2729 ** the system malloc() and free() directly when converting
  2730 ** filenames between the UTF-8 encoding used by SQLite
  2731 ** and whatever filename encoding is used by the particular Windows
  2732 ** installation.  Memory allocation errors were detected, but
  2733 ** they were reported back as [SQLITE_CANTOPEN] or
  2734 ** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
  2735 **
  2736 ** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
  2737 ** must be either NULL or else pointers obtained from a prior
  2738 ** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
  2739 ** not yet been released.
  2740 **
  2741 ** The application must not read or write any part of
  2742 ** a block of memory after it has been released using
  2743 ** [sqlite3_free()] or [sqlite3_realloc()].
  2744 */
  2745 SQLITE_API void *sqlite3_malloc(int);
  2746 SQLITE_API void *sqlite3_malloc64(sqlite3_uint64);
  2747 SQLITE_API void *sqlite3_realloc(void*, int);
  2748 SQLITE_API void *sqlite3_realloc64(void*, sqlite3_uint64);
  2749 SQLITE_API void sqlite3_free(void*);
  2750 SQLITE_API sqlite3_uint64 sqlite3_msize(void*);
  2751 
  2752 /*
  2753 ** CAPI3REF: Memory Allocator Statistics
  2754 **
  2755 ** SQLite provides these two interfaces for reporting on the status
  2756 ** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
  2757 ** routines, which form the built-in memory allocation subsystem.
  2758 **
  2759 ** ^The [sqlite3_memory_used()] routine returns the number of bytes
  2760 ** of memory currently outstanding (malloced but not freed).
  2761 ** ^The [sqlite3_memory_highwater()] routine returns the maximum
  2762 ** value of [sqlite3_memory_used()] since the high-water mark
  2763 ** was last reset.  ^The values returned by [sqlite3_memory_used()] and
  2764 ** [sqlite3_memory_highwater()] include any overhead
  2765 ** added by SQLite in its implementation of [sqlite3_malloc()],
  2766 ** but not overhead added by the any underlying system library
  2767 ** routines that [sqlite3_malloc()] may call.
  2768 **
  2769 ** ^The memory high-water mark is reset to the current value of
  2770 ** [sqlite3_memory_used()] if and only if the parameter to
  2771 ** [sqlite3_memory_highwater()] is true.  ^The value returned
  2772 ** by [sqlite3_memory_highwater(1)] is the high-water mark
  2773 ** prior to the reset.
  2774 */
  2775 SQLITE_API sqlite3_int64 sqlite3_memory_used(void);
  2776 SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag);
  2777 
  2778 /*
  2779 ** CAPI3REF: Pseudo-Random Number Generator
  2780 **
  2781 ** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
  2782 ** select random [ROWID | ROWIDs] when inserting new records into a table that
  2783 ** already uses the largest possible [ROWID].  The PRNG is also used for
  2784 ** the build-in random() and randomblob() SQL functions.  This interface allows
  2785 ** applications to access the same PRNG for other purposes.
  2786 **
  2787 ** ^A call to this routine stores N bytes of randomness into buffer P.
  2788 ** ^The P parameter can be a NULL pointer.
  2789 **
  2790 ** ^If this routine has not been previously called or if the previous
  2791 ** call had N less than one or a NULL pointer for P, then the PRNG is
  2792 ** seeded using randomness obtained from the xRandomness method of
  2793 ** the default [sqlite3_vfs] object.
  2794 ** ^If the previous call to this routine had an N of 1 or more and a
  2795 ** non-NULL P then the pseudo-randomness is generated
  2796 ** internally and without recourse to the [sqlite3_vfs] xRandomness
  2797 ** method.
  2798 */
  2799 SQLITE_API void sqlite3_randomness(int N, void *P);
  2800 
  2801 /*
  2802 ** CAPI3REF: Compile-Time Authorization Callbacks
  2803 ** METHOD: sqlite3
  2804 ** KEYWORDS: {authorizer callback}
  2805 **
  2806 ** ^This routine registers an authorizer callback with a particular
  2807 ** [database connection], supplied in the first argument.
  2808 ** ^The authorizer callback is invoked as SQL statements are being compiled
  2809 ** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
  2810 ** [sqlite3_prepare_v3()], [sqlite3_prepare16()], [sqlite3_prepare16_v2()],
  2811 ** and [sqlite3_prepare16_v3()].  ^At various
  2812 ** points during the compilation process, as logic is being created
  2813 ** to perform various actions, the authorizer callback is invoked to
  2814 ** see if those actions are allowed.  ^The authorizer callback should
  2815 ** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
  2816 ** specific action but allow the SQL statement to continue to be
  2817 ** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
  2818 ** rejected with an error.  ^If the authorizer callback returns
  2819 ** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
  2820 ** then the [sqlite3_prepare_v2()] or equivalent call that triggered
  2821 ** the authorizer will fail with an error message.
  2822 **
  2823 ** When the callback returns [SQLITE_OK], that means the operation
  2824 ** requested is ok.  ^When the callback returns [SQLITE_DENY], the
  2825 ** [sqlite3_prepare_v2()] or equivalent call that triggered the
  2826 ** authorizer will fail with an error message explaining that
  2827 ** access is denied. 
  2828 **
  2829 ** ^The first parameter to the authorizer callback is a copy of the third
  2830 ** parameter to the sqlite3_set_authorizer() interface. ^The second parameter
  2831 ** to the callback is an integer [SQLITE_COPY | action code] that specifies
  2832 ** the particular action to be authorized. ^The third through sixth parameters
  2833 ** to the callback are either NULL pointers or zero-terminated strings
  2834 ** that contain additional details about the action to be authorized.
  2835 ** Applications must always be prepared to encounter a NULL pointer in any
  2836 ** of the third through the sixth parameters of the authorization callback.
  2837 **
  2838 ** ^If the action code is [SQLITE_READ]
  2839 ** and the callback returns [SQLITE_IGNORE] then the
  2840 ** [prepared statement] statement is constructed to substitute
  2841 ** a NULL value in place of the table column that would have
  2842 ** been read if [SQLITE_OK] had been returned.  The [SQLITE_IGNORE]
  2843 ** return can be used to deny an untrusted user access to individual
  2844 ** columns of a table.
  2845 ** ^When a table is referenced by a [SELECT] but no column values are
  2846 ** extracted from that table (for example in a query like
  2847 ** "SELECT count(*) FROM tab") then the [SQLITE_READ] authorizer callback
  2848 ** is invoked once for that table with a column name that is an empty string.
  2849 ** ^If the action code is [SQLITE_DELETE] and the callback returns
  2850 ** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the
  2851 ** [truncate optimization] is disabled and all rows are deleted individually.
  2852 **
  2853 ** An authorizer is used when [sqlite3_prepare | preparing]
  2854 ** SQL statements from an untrusted source, to ensure that the SQL statements
  2855 ** do not try to access data they are not allowed to see, or that they do not
  2856 ** try to execute malicious statements that damage the database.  For
  2857 ** example, an application may allow a user to enter arbitrary
  2858 ** SQL queries for evaluation by a database.  But the application does
  2859 ** not want the user to be able to make arbitrary changes to the
  2860 ** database.  An authorizer could then be put in place while the
  2861 ** user-entered SQL is being [sqlite3_prepare | prepared] that
  2862 ** disallows everything except [SELECT] statements.
  2863 **
  2864 ** Applications that need to process SQL from untrusted sources
  2865 ** might also consider lowering resource limits using [sqlite3_limit()]
  2866 ** and limiting database size using the [max_page_count] [PRAGMA]
  2867 ** in addition to using an authorizer.
  2868 **
  2869 ** ^(Only a single authorizer can be in place on a database connection
  2870 ** at a time.  Each call to sqlite3_set_authorizer overrides the
  2871 ** previous call.)^  ^Disable the authorizer by installing a NULL callback.
  2872 ** The authorizer is disabled by default.
  2873 **
  2874 ** The authorizer callback must not do anything that will modify
  2875 ** the database connection that invoked the authorizer callback.
  2876 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  2877 ** database connections for the meaning of "modify" in this paragraph.
  2878 **
  2879 ** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the
  2880 ** statement might be re-prepared during [sqlite3_step()] due to a 
  2881 ** schema change.  Hence, the application should ensure that the
  2882 ** correct authorizer callback remains in place during the [sqlite3_step()].
  2883 **
  2884 ** ^Note that the authorizer callback is invoked only during
  2885 ** [sqlite3_prepare()] or its variants.  Authorization is not
  2886 ** performed during statement evaluation in [sqlite3_step()], unless
  2887 ** as stated in the previous paragraph, sqlite3_step() invokes
  2888 ** sqlite3_prepare_v2() to reprepare a statement after a schema change.
  2889 */
  2890 SQLITE_API int sqlite3_set_authorizer(
  2891   sqlite3*,
  2892   int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
  2893   void *pUserData
  2894 );
  2895 
  2896 /*
  2897 ** CAPI3REF: Authorizer Return Codes
  2898 **
  2899 ** The [sqlite3_set_authorizer | authorizer callback function] must
  2900 ** return either [SQLITE_OK] or one of these two constants in order
  2901 ** to signal SQLite whether or not the action is permitted.  See the
  2902 ** [sqlite3_set_authorizer | authorizer documentation] for additional
  2903 ** information.
  2904 **
  2905 ** Note that SQLITE_IGNORE is also used as a [conflict resolution mode]
  2906 ** returned from the [sqlite3_vtab_on_conflict()] interface.
  2907 */
  2908 #define SQLITE_DENY   1   /* Abort the SQL statement with an error */
  2909 #define SQLITE_IGNORE 2   /* Don't allow access, but don't generate an error */
  2910 
  2911 /*
  2912 ** CAPI3REF: Authorizer Action Codes
  2913 **
  2914 ** The [sqlite3_set_authorizer()] interface registers a callback function
  2915 ** that is invoked to authorize certain SQL statement actions.  The
  2916 ** second parameter to the callback is an integer code that specifies
  2917 ** what action is being authorized.  These are the integer action codes that
  2918 ** the authorizer callback may be passed.
  2919 **
  2920 ** These action code values signify what kind of operation is to be
  2921 ** authorized.  The 3rd and 4th parameters to the authorization
  2922 ** callback function will be parameters or NULL depending on which of these
  2923 ** codes is used as the second parameter.  ^(The 5th parameter to the
  2924 ** authorizer callback is the name of the database ("main", "temp",
  2925 ** etc.) if applicable.)^  ^The 6th parameter to the authorizer callback
  2926 ** is the name of the inner-most trigger or view that is responsible for
  2927 ** the access attempt or NULL if this access attempt is directly from
  2928 ** top-level SQL code.
  2929 */
  2930 /******************************************* 3rd ************ 4th ***********/
  2931 #define SQLITE_CREATE_INDEX          1   /* Index Name      Table Name      */
  2932 #define SQLITE_CREATE_TABLE          2   /* Table Name      NULL            */
  2933 #define SQLITE_CREATE_TEMP_INDEX     3   /* Index Name      Table Name      */
  2934 #define SQLITE_CREATE_TEMP_TABLE     4   /* Table Name      NULL            */
  2935 #define SQLITE_CREATE_TEMP_TRIGGER   5   /* Trigger Name    Table Name      */
  2936 #define SQLITE_CREATE_TEMP_VIEW      6   /* View Name       NULL            */
  2937 #define SQLITE_CREATE_TRIGGER        7   /* Trigger Name    Table Name      */
  2938 #define SQLITE_CREATE_VIEW           8   /* View Name       NULL            */
  2939 #define SQLITE_DELETE                9   /* Table Name      NULL            */
  2940 #define SQLITE_DROP_INDEX           10   /* Index Name      Table Name      */
  2941 #define SQLITE_DROP_TABLE           11   /* Table Name      NULL            */
  2942 #define SQLITE_DROP_TEMP_INDEX      12   /* Index Name      Table Name      */
  2943 #define SQLITE_DROP_TEMP_TABLE      13   /* Table Name      NULL            */
  2944 #define SQLITE_DROP_TEMP_TRIGGER    14   /* Trigger Name    Table Name      */
  2945 #define SQLITE_DROP_TEMP_VIEW       15   /* View Name       NULL            */
  2946 #define SQLITE_DROP_TRIGGER         16   /* Trigger Name    Table Name      */
  2947 #define SQLITE_DROP_VIEW            17   /* View Name       NULL            */
  2948 #define SQLITE_INSERT               18   /* Table Name      NULL            */
  2949 #define SQLITE_PRAGMA               19   /* Pragma Name     1st arg or NULL */
  2950 #define SQLITE_READ                 20   /* Table Name      Column Name     */
  2951 #define SQLITE_SELECT               21   /* NULL            NULL            */
  2952 #define SQLITE_TRANSACTION          22   /* Operation       NULL            */
  2953 #define SQLITE_UPDATE               23   /* Table Name      Column Name     */
  2954 #define SQLITE_ATTACH               24   /* Filename        NULL            */
  2955 #define SQLITE_DETACH               25   /* Database Name   NULL            */
  2956 #define SQLITE_ALTER_TABLE          26   /* Database Name   Table Name      */
  2957 #define SQLITE_REINDEX              27   /* Index Name      NULL            */
  2958 #define SQLITE_ANALYZE              28   /* Table Name      NULL            */
  2959 #define SQLITE_CREATE_VTABLE        29   /* Table Name      Module Name     */
  2960 #define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
  2961 #define SQLITE_FUNCTION             31   /* NULL            Function Name   */
  2962 #define SQLITE_SAVEPOINT            32   /* Operation       Savepoint Name  */
  2963 #define SQLITE_COPY                  0   /* No longer used */
  2964 #define SQLITE_RECURSIVE            33   /* NULL            NULL            */
  2965 
  2966 /*
  2967 ** CAPI3REF: Tracing And Profiling Functions
  2968 ** METHOD: sqlite3
  2969 **
  2970 ** These routines are deprecated. Use the [sqlite3_trace_v2()] interface
  2971 ** instead of the routines described here.
  2972 **
  2973 ** These routines register callback functions that can be used for
  2974 ** tracing and profiling the execution of SQL statements.
  2975 **
  2976 ** ^The callback function registered by sqlite3_trace() is invoked at
  2977 ** various times when an SQL statement is being run by [sqlite3_step()].
  2978 ** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
  2979 ** SQL statement text as the statement first begins executing.
  2980 ** ^(Additional sqlite3_trace() callbacks might occur
  2981 ** as each triggered subprogram is entered.  The callbacks for triggers
  2982 ** contain a UTF-8 SQL comment that identifies the trigger.)^
  2983 **
  2984 ** The [SQLITE_TRACE_SIZE_LIMIT] compile-time option can be used to limit
  2985 ** the length of [bound parameter] expansion in the output of sqlite3_trace().
  2986 **
  2987 ** ^The callback function registered by sqlite3_profile() is invoked
  2988 ** as each SQL statement finishes.  ^The profile callback contains
  2989 ** the original statement text and an estimate of wall-clock time
  2990 ** of how long that statement took to run.  ^The profile callback
  2991 ** time is in units of nanoseconds, however the current implementation
  2992 ** is only capable of millisecond resolution so the six least significant
  2993 ** digits in the time are meaningless.  Future versions of SQLite
  2994 ** might provide greater resolution on the profiler callback.  The
  2995 ** sqlite3_profile() function is considered experimental and is
  2996 ** subject to change in future versions of SQLite.
  2997 */
  2998 SQLITE_API SQLITE_DEPRECATED void *sqlite3_trace(sqlite3*,
  2999    void(*xTrace)(void*,const char*), void*);
  3000 SQLITE_API SQLITE_DEPRECATED void *sqlite3_profile(sqlite3*,
  3001    void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
  3002 
  3003 /*
  3004 ** CAPI3REF: SQL Trace Event Codes
  3005 ** KEYWORDS: SQLITE_TRACE
  3006 **
  3007 ** These constants identify classes of events that can be monitored
  3008 ** using the [sqlite3_trace_v2()] tracing logic.  The M argument
  3009 ** to [sqlite3_trace_v2(D,M,X,P)] is an OR-ed combination of one or more of
  3010 ** the following constants.  ^The first argument to the trace callback
  3011 ** is one of the following constants.
  3012 **
  3013 ** New tracing constants may be added in future releases.
  3014 **
  3015 ** ^A trace callback has four arguments: xCallback(T,C,P,X).
  3016 ** ^The T argument is one of the integer type codes above.
  3017 ** ^The C argument is a copy of the context pointer passed in as the
  3018 ** fourth argument to [sqlite3_trace_v2()].
  3019 ** The P and X arguments are pointers whose meanings depend on T.
  3020 **
  3021 ** <dl>
  3022 ** [[SQLITE_TRACE_STMT]] <dt>SQLITE_TRACE_STMT</dt>
  3023 ** <dd>^An SQLITE_TRACE_STMT callback is invoked when a prepared statement
  3024 ** first begins running and possibly at other times during the
  3025 ** execution of the prepared statement, such as at the start of each
  3026 ** trigger subprogram. ^The P argument is a pointer to the
  3027 ** [prepared statement]. ^The X argument is a pointer to a string which
  3028 ** is the unexpanded SQL text of the prepared statement or an SQL comment 
  3029 ** that indicates the invocation of a trigger.  ^The callback can compute
  3030 ** the same text that would have been returned by the legacy [sqlite3_trace()]
  3031 ** interface by using the X argument when X begins with "--" and invoking
  3032 ** [sqlite3_expanded_sql(P)] otherwise.
  3033 **
  3034 ** [[SQLITE_TRACE_PROFILE]] <dt>SQLITE_TRACE_PROFILE</dt>
  3035 ** <dd>^An SQLITE_TRACE_PROFILE callback provides approximately the same
  3036 ** information as is provided by the [sqlite3_profile()] callback.
  3037 ** ^The P argument is a pointer to the [prepared statement] and the
  3038 ** X argument points to a 64-bit integer which is the estimated of
  3039 ** the number of nanosecond that the prepared statement took to run.
  3040 ** ^The SQLITE_TRACE_PROFILE callback is invoked when the statement finishes.
  3041 **
  3042 ** [[SQLITE_TRACE_ROW]] <dt>SQLITE_TRACE_ROW</dt>
  3043 ** <dd>^An SQLITE_TRACE_ROW callback is invoked whenever a prepared
  3044 ** statement generates a single row of result.  
  3045 ** ^The P argument is a pointer to the [prepared statement] and the
  3046 ** X argument is unused.
  3047 **
  3048 ** [[SQLITE_TRACE_CLOSE]] <dt>SQLITE_TRACE_CLOSE</dt>
  3049 ** <dd>^An SQLITE_TRACE_CLOSE callback is invoked when a database
  3050 ** connection closes.
  3051 ** ^The P argument is a pointer to the [database connection] object
  3052 ** and the X argument is unused.
  3053 ** </dl>
  3054 */
  3055 #define SQLITE_TRACE_STMT       0x01
  3056 #define SQLITE_TRACE_PROFILE    0x02
  3057 #define SQLITE_TRACE_ROW        0x04
  3058 #define SQLITE_TRACE_CLOSE      0x08
  3059 
  3060 /*
  3061 ** CAPI3REF: SQL Trace Hook
  3062 ** METHOD: sqlite3
  3063 **
  3064 ** ^The sqlite3_trace_v2(D,M,X,P) interface registers a trace callback
  3065 ** function X against [database connection] D, using property mask M
  3066 ** and context pointer P.  ^If the X callback is
  3067 ** NULL or if the M mask is zero, then tracing is disabled.  The
  3068 ** M argument should be the bitwise OR-ed combination of
  3069 ** zero or more [SQLITE_TRACE] constants.
  3070 **
  3071 ** ^Each call to either sqlite3_trace() or sqlite3_trace_v2() overrides 
  3072 ** (cancels) any prior calls to sqlite3_trace() or sqlite3_trace_v2().
  3073 **
  3074 ** ^The X callback is invoked whenever any of the events identified by 
  3075 ** mask M occur.  ^The integer return value from the callback is currently
  3076 ** ignored, though this may change in future releases.  Callback
  3077 ** implementations should return zero to ensure future compatibility.
  3078 **
  3079 ** ^A trace callback is invoked with four arguments: callback(T,C,P,X).
  3080 ** ^The T argument is one of the [SQLITE_TRACE]
  3081 ** constants to indicate why the callback was invoked.
  3082 ** ^The C argument is a copy of the context pointer.
  3083 ** The P and X arguments are pointers whose meanings depend on T.
  3084 **
  3085 ** The sqlite3_trace_v2() interface is intended to replace the legacy
  3086 ** interfaces [sqlite3_trace()] and [sqlite3_profile()], both of which
  3087 ** are deprecated.
  3088 */
  3089 SQLITE_API int sqlite3_trace_v2(
  3090   sqlite3*,
  3091   unsigned uMask,
  3092   int(*xCallback)(unsigned,void*,void*,void*),
  3093   void *pCtx
  3094 );
  3095 
  3096 /*
  3097 ** CAPI3REF: Query Progress Callbacks
  3098 ** METHOD: sqlite3
  3099 **
  3100 ** ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback
  3101 ** function X to be invoked periodically during long running calls to
  3102 ** [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for
  3103 ** database connection D.  An example use for this
  3104 ** interface is to keep a GUI updated during a large query.
  3105 **
  3106 ** ^The parameter P is passed through as the only parameter to the 
  3107 ** callback function X.  ^The parameter N is the approximate number of 
  3108 ** [virtual machine instructions] that are evaluated between successive
  3109 ** invocations of the callback X.  ^If N is less than one then the progress
  3110 ** handler is disabled.
  3111 **
  3112 ** ^Only a single progress handler may be defined at one time per
  3113 ** [database connection]; setting a new progress handler cancels the
  3114 ** old one.  ^Setting parameter X to NULL disables the progress handler.
  3115 ** ^The progress handler is also disabled by setting N to a value less
  3116 ** than 1.
  3117 **
  3118 ** ^If the progress callback returns non-zero, the operation is
  3119 ** interrupted.  This feature can be used to implement a
  3120 ** "Cancel" button on a GUI progress dialog box.
  3121 **
  3122 ** The progress handler callback must not do anything that will modify
  3123 ** the database connection that invoked the progress handler.
  3124 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  3125 ** database connections for the meaning of "modify" in this paragraph.
  3126 **
  3127 */
  3128 SQLITE_API void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
  3129 
  3130 /*
  3131 ** CAPI3REF: Opening A New Database Connection
  3132 ** CONSTRUCTOR: sqlite3
  3133 **
  3134 ** ^These routines open an SQLite database file as specified by the 
  3135 ** filename argument. ^The filename argument is interpreted as UTF-8 for
  3136 ** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
  3137 ** order for sqlite3_open16(). ^(A [database connection] handle is usually
  3138 ** returned in *ppDb, even if an error occurs.  The only exception is that
  3139 ** if SQLite is unable to allocate memory to hold the [sqlite3] object,
  3140 ** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
  3141 ** object.)^ ^(If the database is opened (and/or created) successfully, then
  3142 ** [SQLITE_OK] is returned.  Otherwise an [error code] is returned.)^ ^The
  3143 ** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
  3144 ** an English language description of the error following a failure of any
  3145 ** of the sqlite3_open() routines.
  3146 **
  3147 ** ^The default encoding will be UTF-8 for databases created using
  3148 ** sqlite3_open() or sqlite3_open_v2().  ^The default encoding for databases
  3149 ** created using sqlite3_open16() will be UTF-16 in the native byte order.
  3150 **
  3151 ** Whether or not an error occurs when it is opened, resources
  3152 ** associated with the [database connection] handle should be released by
  3153 ** passing it to [sqlite3_close()] when it is no longer required.
  3154 **
  3155 ** The sqlite3_open_v2() interface works like sqlite3_open()
  3156 ** except that it accepts two additional parameters for additional control
  3157 ** over the new database connection.  ^(The flags parameter to
  3158 ** sqlite3_open_v2() can take one of
  3159 ** the following three values, optionally combined with the 
  3160 ** [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE],
  3161 ** [SQLITE_OPEN_PRIVATECACHE], and/or [SQLITE_OPEN_URI] flags:)^
  3162 **
  3163 ** <dl>
  3164 ** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
  3165 ** <dd>The database is opened in read-only mode.  If the database does not
  3166 ** already exist, an error is returned.</dd>)^
  3167 **
  3168 ** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
  3169 ** <dd>The database is opened for reading and writing if possible, or reading
  3170 ** only if the file is write protected by the operating system.  In either
  3171 ** case the database must already exist, otherwise an error is returned.</dd>)^
  3172 **
  3173 ** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
  3174 ** <dd>The database is opened for reading and writing, and is created if
  3175 ** it does not already exist. This is the behavior that is always used for
  3176 ** sqlite3_open() and sqlite3_open16().</dd>)^
  3177 ** </dl>
  3178 **
  3179 ** If the 3rd parameter to sqlite3_open_v2() is not one of the
  3180 ** combinations shown above optionally combined with other
  3181 ** [SQLITE_OPEN_READONLY | SQLITE_OPEN_* bits]
  3182 ** then the behavior is undefined.
  3183 **
  3184 ** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
  3185 ** opens in the multi-thread [threading mode] as long as the single-thread
  3186 ** mode has not been set at compile-time or start-time.  ^If the
  3187 ** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
  3188 ** in the serialized [threading mode] unless single-thread was
  3189 ** previously selected at compile-time or start-time.
  3190 ** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be
  3191 ** eligible to use [shared cache mode], regardless of whether or not shared
  3192 ** cache is enabled using [sqlite3_enable_shared_cache()].  ^The
  3193 ** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not
  3194 ** participate in [shared cache mode] even if it is enabled.
  3195 **
  3196 ** ^The fourth parameter to sqlite3_open_v2() is the name of the
  3197 ** [sqlite3_vfs] object that defines the operating system interface that
  3198 ** the new database connection should use.  ^If the fourth parameter is
  3199 ** a NULL pointer then the default [sqlite3_vfs] object is used.
  3200 **
  3201 ** ^If the filename is ":memory:", then a private, temporary in-memory database
  3202 ** is created for the connection.  ^This in-memory database will vanish when
  3203 ** the database connection is closed.  Future versions of SQLite might
  3204 ** make use of additional special filenames that begin with the ":" character.
  3205 ** It is recommended that when a database filename actually does begin with
  3206 ** a ":" character you should prefix the filename with a pathname such as
  3207 ** "./" to avoid ambiguity.
  3208 **
  3209 ** ^If the filename is an empty string, then a private, temporary
  3210 ** on-disk database will be created.  ^This private database will be
  3211 ** automatically deleted as soon as the database connection is closed.
  3212 **
  3213 ** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
  3214 **
  3215 ** ^If [URI filename] interpretation is enabled, and the filename argument
  3216 ** begins with "file:", then the filename is interpreted as a URI. ^URI
  3217 ** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
  3218 ** set in the third argument to sqlite3_open_v2(), or if it has
  3219 ** been enabled globally using the [SQLITE_CONFIG_URI] option with the
  3220 ** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
  3221 ** URI filename interpretation is turned off
  3222 ** by default, but future releases of SQLite might enable URI filename
  3223 ** interpretation by default.  See "[URI filenames]" for additional
  3224 ** information.
  3225 **
  3226 ** URI filenames are parsed according to RFC 3986. ^If the URI contains an
  3227 ** authority, then it must be either an empty string or the string 
  3228 ** "localhost". ^If the authority is not an empty string or "localhost", an 
  3229 ** error is returned to the caller. ^The fragment component of a URI, if 
  3230 ** present, is ignored.
  3231 **
  3232 ** ^SQLite uses the path component of the URI as the name of the disk file
  3233 ** which contains the database. ^If the path begins with a '/' character, 
  3234 ** then it is interpreted as an absolute path. ^If the path does not begin 
  3235 ** with a '/' (meaning that the authority section is omitted from the URI)
  3236 ** then the path is interpreted as a relative path. 
  3237 ** ^(On windows, the first component of an absolute path 
  3238 ** is a drive specification (e.g. "C:").)^
  3239 **
  3240 ** [[core URI query parameters]]
  3241 ** The query component of a URI may contain parameters that are interpreted
  3242 ** either by SQLite itself, or by a [VFS | custom VFS implementation].
  3243 ** SQLite and its built-in [VFSes] interpret the
  3244 ** following query parameters:
  3245 **
  3246 ** <ul>
  3247 **   <li> <b>vfs</b>: ^The "vfs" parameter may be used to specify the name of
  3248 **     a VFS object that provides the operating system interface that should
  3249 **     be used to access the database file on disk. ^If this option is set to
  3250 **     an empty string the default VFS object is used. ^Specifying an unknown
  3251 **     VFS is an error. ^If sqlite3_open_v2() is used and the vfs option is
  3252 **     present, then the VFS specified by the option takes precedence over
  3253 **     the value passed as the fourth parameter to sqlite3_open_v2().
  3254 **
  3255 **   <li> <b>mode</b>: ^(The mode parameter may be set to either "ro", "rw",
  3256 **     "rwc", or "memory". Attempting to set it to any other value is
  3257 **     an error)^. 
  3258 **     ^If "ro" is specified, then the database is opened for read-only 
  3259 **     access, just as if the [SQLITE_OPEN_READONLY] flag had been set in the 
  3260 **     third argument to sqlite3_open_v2(). ^If the mode option is set to 
  3261 **     "rw", then the database is opened for read-write (but not create) 
  3262 **     access, as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had 
  3263 **     been set. ^Value "rwc" is equivalent to setting both 
  3264 **     SQLITE_OPEN_READWRITE and SQLITE_OPEN_CREATE.  ^If the mode option is
  3265 **     set to "memory" then a pure [in-memory database] that never reads
  3266 **     or writes from disk is used. ^It is an error to specify a value for
  3267 **     the mode parameter that is less restrictive than that specified by
  3268 **     the flags passed in the third parameter to sqlite3_open_v2().
  3269 **
  3270 **   <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or
  3271 **     "private". ^Setting it to "shared" is equivalent to setting the
  3272 **     SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to
  3273 **     sqlite3_open_v2(). ^Setting the cache parameter to "private" is 
  3274 **     equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit.
  3275 **     ^If sqlite3_open_v2() is used and the "cache" parameter is present in
  3276 **     a URI filename, its value overrides any behavior requested by setting
  3277 **     SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag.
  3278 **
  3279 **  <li> <b>psow</b>: ^The psow parameter indicates whether or not the
  3280 **     [powersafe overwrite] property does or does not apply to the
  3281 **     storage media on which the database file resides.
  3282 **
  3283 **  <li> <b>nolock</b>: ^The nolock parameter is a boolean query parameter
  3284 **     which if set disables file locking in rollback journal modes.  This
  3285 **     is useful for accessing a database on a filesystem that does not
  3286 **     support locking.  Caution:  Database corruption might result if two
  3287 **     or more processes write to the same database and any one of those
  3288 **     processes uses nolock=1.
  3289 **
  3290 **  <li> <b>immutable</b>: ^The immutable parameter is a boolean query
  3291 **     parameter that indicates that the database file is stored on
  3292 **     read-only media.  ^When immutable is set, SQLite assumes that the
  3293 **     database file cannot be changed, even by a process with higher
  3294 **     privilege, and so the database is opened read-only and all locking
  3295 **     and change detection is disabled.  Caution: Setting the immutable
  3296 **     property on a database file that does in fact change can result
  3297 **     in incorrect query results and/or [SQLITE_CORRUPT] errors.
  3298 **     See also: [SQLITE_IOCAP_IMMUTABLE].
  3299 **       
  3300 ** </ul>
  3301 **
  3302 ** ^Specifying an unknown parameter in the query component of a URI is not an
  3303 ** error.  Future versions of SQLite might understand additional query
  3304 ** parameters.  See "[query parameters with special meaning to SQLite]" for
  3305 ** additional information.
  3306 **
  3307 ** [[URI filename examples]] <h3>URI filename examples</h3>
  3308 **
  3309 ** <table border="1" align=center cellpadding=5>
  3310 ** <tr><th> URI filenames <th> Results
  3311 ** <tr><td> file:data.db <td> 
  3312 **          Open the file "data.db" in the current directory.
  3313 ** <tr><td> file:/home/fred/data.db<br>
  3314 **          file:///home/fred/data.db <br> 
  3315 **          file://localhost/home/fred/data.db <br> <td> 
  3316 **          Open the database file "/home/fred/data.db".
  3317 ** <tr><td> file://darkstar/home/fred/data.db <td> 
  3318 **          An error. "darkstar" is not a recognized authority.
  3319 ** <tr><td style="white-space:nowrap"> 
  3320 **          file:///C:/Documents%20and%20Settings/fred/Desktop/data.db
  3321 **     <td> Windows only: Open the file "data.db" on fred's desktop on drive
  3322 **          C:. Note that the %20 escaping in this example is not strictly 
  3323 **          necessary - space characters can be used literally
  3324 **          in URI filenames.
  3325 ** <tr><td> file:data.db?mode=ro&cache=private <td> 
  3326 **          Open file "data.db" in the current directory for read-only access.
  3327 **          Regardless of whether or not shared-cache mode is enabled by
  3328 **          default, use a private cache.
  3329 ** <tr><td> file:/home/fred/data.db?vfs=unix-dotfile <td>
  3330 **          Open file "/home/fred/data.db". Use the special VFS "unix-dotfile"
  3331 **          that uses dot-files in place of posix advisory locking.
  3332 ** <tr><td> file:data.db?mode=readonly <td> 
  3333 **          An error. "readonly" is not a valid option for the "mode" parameter.
  3334 ** </table>
  3335 **
  3336 ** ^URI hexadecimal escape sequences (%HH) are supported within the path and
  3337 ** query components of a URI. A hexadecimal escape sequence consists of a
  3338 ** percent sign - "%" - followed by exactly two hexadecimal digits 
  3339 ** specifying an octet value. ^Before the path or query components of a
  3340 ** URI filename are interpreted, they are encoded using UTF-8 and all 
  3341 ** hexadecimal escape sequences replaced by a single byte containing the
  3342 ** corresponding octet. If this process generates an invalid UTF-8 encoding,
  3343 ** the results are undefined.
  3344 **
  3345 ** <b>Note to Windows users:</b>  The encoding used for the filename argument
  3346 ** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
  3347 ** codepage is currently defined.  Filenames containing international
  3348 ** characters must be converted to UTF-8 prior to passing them into
  3349 ** sqlite3_open() or sqlite3_open_v2().
  3350 **
  3351 ** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
  3352 ** prior to calling sqlite3_open() or sqlite3_open_v2().  Otherwise, various
  3353 ** features that require the use of temporary files may fail.
  3354 **
  3355 ** See also: [sqlite3_temp_directory]
  3356 */
  3357 SQLITE_API int sqlite3_open(
  3358   const char *filename,   /* Database filename (UTF-8) */
  3359   sqlite3 **ppDb          /* OUT: SQLite db handle */
  3360 );
  3361 SQLITE_API int sqlite3_open16(
  3362   const void *filename,   /* Database filename (UTF-16) */
  3363   sqlite3 **ppDb          /* OUT: SQLite db handle */
  3364 );
  3365 SQLITE_API int sqlite3_open_v2(
  3366   const char *filename,   /* Database filename (UTF-8) */
  3367   sqlite3 **ppDb,         /* OUT: SQLite db handle */
  3368   int flags,              /* Flags */
  3369   const char *zVfs        /* Name of VFS module to use */
  3370 );
  3371 
  3372 /*
  3373 ** CAPI3REF: Obtain Values For URI Parameters
  3374 **
  3375 ** These are utility routines, useful to VFS implementations, that check
  3376 ** to see if a database file was a URI that contained a specific query 
  3377 ** parameter, and if so obtains the value of that query parameter.
  3378 **
  3379 ** If F is the database filename pointer passed into the xOpen() method of 
  3380 ** a VFS implementation when the flags parameter to xOpen() has one or 
  3381 ** more of the [SQLITE_OPEN_URI] or [SQLITE_OPEN_MAIN_DB] bits set and
  3382 ** P is the name of the query parameter, then
  3383 ** sqlite3_uri_parameter(F,P) returns the value of the P
  3384 ** parameter if it exists or a NULL pointer if P does not appear as a 
  3385 ** query parameter on F.  If P is a query parameter of F
  3386 ** has no explicit value, then sqlite3_uri_parameter(F,P) returns
  3387 ** a pointer to an empty string.
  3388 **
  3389 ** The sqlite3_uri_boolean(F,P,B) routine assumes that P is a boolean
  3390 ** parameter and returns true (1) or false (0) according to the value
  3391 ** of P.  The sqlite3_uri_boolean(F,P,B) routine returns true (1) if the
  3392 ** value of query parameter P is one of "yes", "true", or "on" in any
  3393 ** case or if the value begins with a non-zero number.  The 
  3394 ** sqlite3_uri_boolean(F,P,B) routines returns false (0) if the value of
  3395 ** query parameter P is one of "no", "false", or "off" in any case or
  3396 ** if the value begins with a numeric zero.  If P is not a query
  3397 ** parameter on F or if the value of P is does not match any of the
  3398 ** above, then sqlite3_uri_boolean(F,P,B) returns (B!=0).
  3399 **
  3400 ** The sqlite3_uri_int64(F,P,D) routine converts the value of P into a
  3401 ** 64-bit signed integer and returns that integer, or D if P does not
  3402 ** exist.  If the value of P is something other than an integer, then
  3403 ** zero is returned.
  3404 ** 
  3405 ** If F is a NULL pointer, then sqlite3_uri_parameter(F,P) returns NULL and
  3406 ** sqlite3_uri_boolean(F,P,B) returns B.  If F is not a NULL pointer and
  3407 ** is not a database file pathname pointer that SQLite passed into the xOpen
  3408 ** VFS method, then the behavior of this routine is undefined and probably
  3409 ** undesirable.
  3410 */
  3411 SQLITE_API const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam);
  3412 SQLITE_API int sqlite3_uri_boolean(const char *zFile, const char *zParam, int bDefault);
  3413 SQLITE_API sqlite3_int64 sqlite3_uri_int64(const char*, const char*, sqlite3_int64);
  3414 
  3415 
  3416 /*
  3417 ** CAPI3REF: Error Codes And Messages
  3418 ** METHOD: sqlite3
  3419 **
  3420 ** ^If the most recent sqlite3_* API call associated with 
  3421 ** [database connection] D failed, then the sqlite3_errcode(D) interface
  3422 ** returns the numeric [result code] or [extended result code] for that
  3423 ** API call.
  3424 ** ^The sqlite3_extended_errcode()
  3425 ** interface is the same except that it always returns the 
  3426 ** [extended result code] even when extended result codes are
  3427 ** disabled.
  3428 **
  3429 ** The values returned by sqlite3_errcode() and/or
  3430 ** sqlite3_extended_errcode() might change with each API call.
  3431 ** Except, there are some interfaces that are guaranteed to never
  3432 ** change the value of the error code.  The error-code preserving
  3433 ** interfaces are:
  3434 **
  3435 ** <ul>
  3436 ** <li> sqlite3_errcode()
  3437 ** <li> sqlite3_extended_errcode()
  3438 ** <li> sqlite3_errmsg()
  3439 ** <li> sqlite3_errmsg16()
  3440 ** </ul>
  3441 **
  3442 ** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
  3443 ** text that describes the error, as either UTF-8 or UTF-16 respectively.
  3444 ** ^(Memory to hold the error message string is managed internally.
  3445 ** The application does not need to worry about freeing the result.
  3446 ** However, the error string might be overwritten or deallocated by
  3447 ** subsequent calls to other SQLite interface functions.)^
  3448 **
  3449 ** ^The sqlite3_errstr() interface returns the English-language text
  3450 ** that describes the [result code], as UTF-8.
  3451 ** ^(Memory to hold the error message string is managed internally
  3452 ** and must not be freed by the application)^.
  3453 **
  3454 ** When the serialized [threading mode] is in use, it might be the
  3455 ** case that a second error occurs on a separate thread in between
  3456 ** the time of the first error and the call to these interfaces.
  3457 ** When that happens, the second error will be reported since these
  3458 ** interfaces always report the most recent result.  To avoid
  3459 ** this, each thread can obtain exclusive use of the [database connection] D
  3460 ** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
  3461 ** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
  3462 ** all calls to the interfaces listed here are completed.
  3463 **
  3464 ** If an interface fails with SQLITE_MISUSE, that means the interface
  3465 ** was invoked incorrectly by the application.  In that case, the
  3466 ** error code and message may or may not be set.
  3467 */
  3468 SQLITE_API int sqlite3_errcode(sqlite3 *db);
  3469 SQLITE_API int sqlite3_extended_errcode(sqlite3 *db);
  3470 SQLITE_API const char *sqlite3_errmsg(sqlite3*);
  3471 SQLITE_API const void *sqlite3_errmsg16(sqlite3*);
  3472 SQLITE_API const char *sqlite3_errstr(int);
  3473 
  3474 /*
  3475 ** CAPI3REF: Prepared Statement Object
  3476 ** KEYWORDS: {prepared statement} {prepared statements}
  3477 **
  3478 ** An instance of this object represents a single SQL statement that
  3479 ** has been compiled into binary form and is ready to be evaluated.
  3480 **
  3481 ** Think of each SQL statement as a separate computer program.  The
  3482 ** original SQL text is source code.  A prepared statement object 
  3483 ** is the compiled object code.  All SQL must be converted into a
  3484 ** prepared statement before it can be run.
  3485 **
  3486 ** The life-cycle of a prepared statement object usually goes like this:
  3487 **
  3488 ** <ol>
  3489 ** <li> Create the prepared statement object using [sqlite3_prepare_v2()].
  3490 ** <li> Bind values to [parameters] using the sqlite3_bind_*()
  3491 **      interfaces.
  3492 ** <li> Run the SQL by calling [sqlite3_step()] one or more times.
  3493 ** <li> Reset the prepared statement using [sqlite3_reset()] then go back
  3494 **      to step 2.  Do this zero or more times.
  3495 ** <li> Destroy the object using [sqlite3_finalize()].
  3496 ** </ol>
  3497 */
  3498 typedef struct sqlite3_stmt sqlite3_stmt;
  3499 
  3500 /*
  3501 ** CAPI3REF: Run-time Limits
  3502 ** METHOD: sqlite3
  3503 **
  3504 ** ^(This interface allows the size of various constructs to be limited
  3505 ** on a connection by connection basis.  The first parameter is the
  3506 ** [database connection] whose limit is to be set or queried.  The
  3507 ** second parameter is one of the [limit categories] that define a
  3508 ** class of constructs to be size limited.  The third parameter is the
  3509 ** new limit for that construct.)^
  3510 **
  3511 ** ^If the new limit is a negative number, the limit is unchanged.
  3512 ** ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a 
  3513 ** [limits | hard upper bound]
  3514 ** set at compile-time by a C preprocessor macro called
  3515 ** [limits | SQLITE_MAX_<i>NAME</i>].
  3516 ** (The "_LIMIT_" in the name is changed to "_MAX_".))^
  3517 ** ^Attempts to increase a limit above its hard upper bound are
  3518 ** silently truncated to the hard upper bound.
  3519 **
  3520 ** ^Regardless of whether or not the limit was changed, the 
  3521 ** [sqlite3_limit()] interface returns the prior value of the limit.
  3522 ** ^Hence, to find the current value of a limit without changing it,
  3523 ** simply invoke this interface with the third parameter set to -1.
  3524 **
  3525 ** Run-time limits are intended for use in applications that manage
  3526 ** both their own internal database and also databases that are controlled
  3527 ** by untrusted external sources.  An example application might be a
  3528 ** web browser that has its own databases for storing history and
  3529 ** separate databases controlled by JavaScript applications downloaded
  3530 ** off the Internet.  The internal databases can be given the
  3531 ** large, default limits.  Databases managed by external sources can
  3532 ** be given much smaller limits designed to prevent a denial of service
  3533 ** attack.  Developers might also want to use the [sqlite3_set_authorizer()]
  3534 ** interface to further control untrusted SQL.  The size of the database
  3535 ** created by an untrusted script can be contained using the
  3536 ** [max_page_count] [PRAGMA].
  3537 **
  3538 ** New run-time limit categories may be added in future releases.
  3539 */
  3540 SQLITE_API int sqlite3_limit(sqlite3*, int id, int newVal);
  3541 
  3542 /*
  3543 ** CAPI3REF: Run-Time Limit Categories
  3544 ** KEYWORDS: {limit category} {*limit categories}
  3545 **
  3546 ** These constants define various performance limits
  3547 ** that can be lowered at run-time using [sqlite3_limit()].
  3548 ** The synopsis of the meanings of the various limits is shown below.
  3549 ** Additional information is available at [limits | Limits in SQLite].
  3550 **
  3551 ** <dl>
  3552 ** [[SQLITE_LIMIT_LENGTH]] ^(<dt>SQLITE_LIMIT_LENGTH</dt>
  3553 ** <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^
  3554 **
  3555 ** [[SQLITE_LIMIT_SQL_LENGTH]] ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt>
  3556 ** <dd>The maximum length of an SQL statement, in bytes.</dd>)^
  3557 **
  3558 ** [[SQLITE_LIMIT_COLUMN]] ^(<dt>SQLITE_LIMIT_COLUMN</dt>
  3559 ** <dd>The maximum number of columns in a table definition or in the
  3560 ** result set of a [SELECT] or the maximum number of columns in an index
  3561 ** or in an ORDER BY or GROUP BY clause.</dd>)^
  3562 **
  3563 ** [[SQLITE_LIMIT_EXPR_DEPTH]] ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
  3564 ** <dd>The maximum depth of the parse tree on any expression.</dd>)^
  3565 **
  3566 ** [[SQLITE_LIMIT_COMPOUND_SELECT]] ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
  3567 ** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^
  3568 **
  3569 ** [[SQLITE_LIMIT_VDBE_OP]] ^(<dt>SQLITE_LIMIT_VDBE_OP</dt>
  3570 ** <dd>The maximum number of instructions in a virtual machine program
  3571 ** used to implement an SQL statement.  If [sqlite3_prepare_v2()] or
  3572 ** the equivalent tries to allocate space for more than this many opcodes
  3573 ** in a single prepared statement, an SQLITE_NOMEM error is returned.</dd>)^
  3574 **
  3575 ** [[SQLITE_LIMIT_FUNCTION_ARG]] ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
  3576 ** <dd>The maximum number of arguments on a function.</dd>)^
  3577 **
  3578 ** [[SQLITE_LIMIT_ATTACHED]] ^(<dt>SQLITE_LIMIT_ATTACHED</dt>
  3579 ** <dd>The maximum number of [ATTACH | attached databases].)^</dd>
  3580 **
  3581 ** [[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]]
  3582 ** ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
  3583 ** <dd>The maximum length of the pattern argument to the [LIKE] or
  3584 ** [GLOB] operators.</dd>)^
  3585 **
  3586 ** [[SQLITE_LIMIT_VARIABLE_NUMBER]]
  3587 ** ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
  3588 ** <dd>The maximum index number of any [parameter] in an SQL statement.)^
  3589 **
  3590 ** [[SQLITE_LIMIT_TRIGGER_DEPTH]] ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt>
  3591 ** <dd>The maximum depth of recursion for triggers.</dd>)^
  3592 **
  3593 ** [[SQLITE_LIMIT_WORKER_THREADS]] ^(<dt>SQLITE_LIMIT_WORKER_THREADS</dt>
  3594 ** <dd>The maximum number of auxiliary worker threads that a single
  3595 ** [prepared statement] may start.</dd>)^
  3596 ** </dl>
  3597 */
  3598 #define SQLITE_LIMIT_LENGTH                    0
  3599 #define SQLITE_LIMIT_SQL_LENGTH                1
  3600 #define SQLITE_LIMIT_COLUMN                    2
  3601 #define SQLITE_LIMIT_EXPR_DEPTH                3
  3602 #define SQLITE_LIMIT_COMPOUND_SELECT           4
  3603 #define SQLITE_LIMIT_VDBE_OP                   5
  3604 #define SQLITE_LIMIT_FUNCTION_ARG              6
  3605 #define SQLITE_LIMIT_ATTACHED                  7
  3606 #define SQLITE_LIMIT_LIKE_PATTERN_LENGTH       8
  3607 #define SQLITE_LIMIT_VARIABLE_NUMBER           9
  3608 #define SQLITE_LIMIT_TRIGGER_DEPTH            10
  3609 #define SQLITE_LIMIT_WORKER_THREADS           11
  3610 
  3611 /*
  3612 ** CAPI3REF: Prepare Flags
  3613 **
  3614 ** These constants define various flags that can be passed into
  3615 ** "prepFlags" parameter of the [sqlite3_prepare_v3()] and
  3616 ** [sqlite3_prepare16_v3()] interfaces.
  3617 **
  3618 ** New flags may be added in future releases of SQLite.
  3619 **
  3620 ** <dl>
  3621 ** [[SQLITE_PREPARE_PERSISTENT]] ^(<dt>SQLITE_PREPARE_PERSISTENT</dt>
  3622 ** <dd>The SQLITE_PREPARE_PERSISTENT flag is a hint to the query planner
  3623 ** that the prepared statement will be retained for a long time and
  3624 ** probably reused many times.)^ ^Without this flag, [sqlite3_prepare_v3()]
  3625 ** and [sqlite3_prepare16_v3()] assume that the prepared statement will 
  3626 ** be used just once or at most a few times and then destroyed using
  3627 ** [sqlite3_finalize()] relatively soon. The current implementation acts
  3628 ** on this hint by avoiding the use of [lookaside memory] so as not to
  3629 ** deplete the limited store of lookaside memory. Future versions of
  3630 ** SQLite may act on this hint differently.
  3631 **
  3632 ** [[SQLITE_PREPARE_NORMALIZE]] ^(<dt>SQLITE_PREPARE_NORMALIZE</dt>
  3633 ** <dd>The SQLITE_PREPARE_NORMALIZE flag indicates that a normalized
  3634 ** representation of the SQL statement should be calculated and then
  3635 ** associated with the prepared statement, which can be obtained via
  3636 ** the [sqlite3_normalized_sql()] interface.)^  The semantics used to
  3637 ** normalize a SQL statement are unspecified and subject to change.
  3638 ** At a minimum, literal values will be replaced with suitable
  3639 ** placeholders.
  3640 ** </dl>
  3641 */
  3642 #define SQLITE_PREPARE_PERSISTENT              0x01
  3643 #define SQLITE_PREPARE_NORMALIZE               0x02
  3644 
  3645 /*
  3646 ** CAPI3REF: Compiling An SQL Statement
  3647 ** KEYWORDS: {SQL statement compiler}
  3648 ** METHOD: sqlite3
  3649 ** CONSTRUCTOR: sqlite3_stmt
  3650 **
  3651 ** To execute an SQL statement, it must first be compiled into a byte-code
  3652 ** program using one of these routines.  Or, in other words, these routines
  3653 ** are constructors for the [prepared statement] object.
  3654 **
  3655 ** The preferred routine to use is [sqlite3_prepare_v2()].  The
  3656 ** [sqlite3_prepare()] interface is legacy and should be avoided.
  3657 ** [sqlite3_prepare_v3()] has an extra "prepFlags" option that is used
  3658 ** for special purposes.
  3659 **
  3660 ** The use of the UTF-8 interfaces is preferred, as SQLite currently
  3661 ** does all parsing using UTF-8.  The UTF-16 interfaces are provided
  3662 ** as a convenience.  The UTF-16 interfaces work by converting the
  3663 ** input text into UTF-8, then invoking the corresponding UTF-8 interface.
  3664 **
  3665 ** The first argument, "db", is a [database connection] obtained from a
  3666 ** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or
  3667 ** [sqlite3_open16()].  The database connection must not have been closed.
  3668 **
  3669 ** The second argument, "zSql", is the statement to be compiled, encoded
  3670 ** as either UTF-8 or UTF-16.  The sqlite3_prepare(), sqlite3_prepare_v2(),
  3671 ** and sqlite3_prepare_v3()
  3672 ** interfaces use UTF-8, and sqlite3_prepare16(), sqlite3_prepare16_v2(),
  3673 ** and sqlite3_prepare16_v3() use UTF-16.
  3674 **
  3675 ** ^If the nByte argument is negative, then zSql is read up to the
  3676 ** first zero terminator. ^If nByte is positive, then it is the
  3677 ** number of bytes read from zSql.  ^If nByte is zero, then no prepared
  3678 ** statement is generated.
  3679 ** If the caller knows that the supplied string is nul-terminated, then
  3680 ** there is a small performance advantage to passing an nByte parameter that
  3681 ** is the number of bytes in the input string <i>including</i>
  3682 ** the nul-terminator.
  3683 **
  3684 ** ^If pzTail is not NULL then *pzTail is made to point to the first byte
  3685 ** past the end of the first SQL statement in zSql.  These routines only
  3686 ** compile the first statement in zSql, so *pzTail is left pointing to
  3687 ** what remains uncompiled.
  3688 **
  3689 ** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
  3690 ** executed using [sqlite3_step()].  ^If there is an error, *ppStmt is set
  3691 ** to NULL.  ^If the input text contains no SQL (if the input is an empty
  3692 ** string or a comment) then *ppStmt is set to NULL.
  3693 ** The calling procedure is responsible for deleting the compiled
  3694 ** SQL statement using [sqlite3_finalize()] after it has finished with it.
  3695 ** ppStmt may not be NULL.
  3696 **
  3697 ** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK];
  3698 ** otherwise an [error code] is returned.
  3699 **
  3700 ** The sqlite3_prepare_v2(), sqlite3_prepare_v3(), sqlite3_prepare16_v2(),
  3701 ** and sqlite3_prepare16_v3() interfaces are recommended for all new programs.
  3702 ** The older interfaces (sqlite3_prepare() and sqlite3_prepare16())
  3703 ** are retained for backwards compatibility, but their use is discouraged.
  3704 ** ^In the "vX" interfaces, the prepared statement
  3705 ** that is returned (the [sqlite3_stmt] object) contains a copy of the
  3706 ** original SQL text. This causes the [sqlite3_step()] interface to
  3707 ** behave differently in three ways:
  3708 **
  3709 ** <ol>
  3710 ** <li>
  3711 ** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
  3712 ** always used to do, [sqlite3_step()] will automatically recompile the SQL
  3713 ** statement and try to run it again. As many as [SQLITE_MAX_SCHEMA_RETRY]
  3714 ** retries will occur before sqlite3_step() gives up and returns an error.
  3715 ** </li>
  3716 **
  3717 ** <li>
  3718 ** ^When an error occurs, [sqlite3_step()] will return one of the detailed
  3719 ** [error codes] or [extended error codes].  ^The legacy behavior was that
  3720 ** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
  3721 ** and the application would have to make a second call to [sqlite3_reset()]
  3722 ** in order to find the underlying cause of the problem. With the "v2" prepare
  3723 ** interfaces, the underlying reason for the error is returned immediately.
  3724 ** </li>
  3725 **
  3726 ** <li>
  3727 ** ^If the specific value bound to [parameter | host parameter] in the 
  3728 ** WHERE clause might influence the choice of query plan for a statement,
  3729 ** then the statement will be automatically recompiled, as if there had been 
  3730 ** a schema change, on the first  [sqlite3_step()] call following any change
  3731 ** to the [sqlite3_bind_text | bindings] of that [parameter]. 
  3732 ** ^The specific value of WHERE-clause [parameter] might influence the 
  3733 ** choice of query plan if the parameter is the left-hand side of a [LIKE]
  3734 ** or [GLOB] operator or if the parameter is compared to an indexed column
  3735 ** and the [SQLITE_ENABLE_STAT3] compile-time option is enabled.
  3736 ** </li>
  3737 ** </ol>
  3738 **
  3739 ** <p>^sqlite3_prepare_v3() differs from sqlite3_prepare_v2() only in having
  3740 ** the extra prepFlags parameter, which is a bit array consisting of zero or
  3741 ** more of the [SQLITE_PREPARE_PERSISTENT|SQLITE_PREPARE_*] flags.  ^The
  3742 ** sqlite3_prepare_v2() interface works exactly the same as
  3743 ** sqlite3_prepare_v3() with a zero prepFlags parameter.
  3744 */
  3745 SQLITE_API int sqlite3_prepare(
  3746   sqlite3 *db,            /* Database handle */
  3747   const char *zSql,       /* SQL statement, UTF-8 encoded */
  3748   int nByte,              /* Maximum length of zSql in bytes. */
  3749   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3750   const char **pzTail     /* OUT: Pointer to unused portion of zSql */
  3751 );
  3752 SQLITE_API int sqlite3_prepare_v2(
  3753   sqlite3 *db,            /* Database handle */
  3754   const char *zSql,       /* SQL statement, UTF-8 encoded */
  3755   int nByte,              /* Maximum length of zSql in bytes. */
  3756   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3757   const char **pzTail     /* OUT: Pointer to unused portion of zSql */
  3758 );
  3759 SQLITE_API int sqlite3_prepare_v3(
  3760   sqlite3 *db,            /* Database handle */
  3761   const char *zSql,       /* SQL statement, UTF-8 encoded */
  3762   int nByte,              /* Maximum length of zSql in bytes. */
  3763   unsigned int prepFlags, /* Zero or more SQLITE_PREPARE_ flags */
  3764   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3765   const char **pzTail     /* OUT: Pointer to unused portion of zSql */
  3766 );
  3767 SQLITE_API int sqlite3_prepare16(
  3768   sqlite3 *db,            /* Database handle */
  3769   const void *zSql,       /* SQL statement, UTF-16 encoded */
  3770   int nByte,              /* Maximum length of zSql in bytes. */
  3771   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3772   const void **pzTail     /* OUT: Pointer to unused portion of zSql */
  3773 );
  3774 SQLITE_API int sqlite3_prepare16_v2(
  3775   sqlite3 *db,            /* Database handle */
  3776   const void *zSql,       /* SQL statement, UTF-16 encoded */
  3777   int nByte,              /* Maximum length of zSql in bytes. */
  3778   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3779   const void **pzTail     /* OUT: Pointer to unused portion of zSql */
  3780 );
  3781 SQLITE_API int sqlite3_prepare16_v3(
  3782   sqlite3 *db,            /* Database handle */
  3783   const void *zSql,       /* SQL statement, UTF-16 encoded */
  3784   int nByte,              /* Maximum length of zSql in bytes. */
  3785   unsigned int prepFlags, /* Zero or more SQLITE_PREPARE_ flags */
  3786   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3787   const void **pzTail     /* OUT: Pointer to unused portion of zSql */
  3788 );
  3789 
  3790 /*
  3791 ** CAPI3REF: Retrieving Statement SQL
  3792 ** METHOD: sqlite3_stmt
  3793 **
  3794 ** ^The sqlite3_sql(P) interface returns a pointer to a copy of the UTF-8
  3795 ** SQL text used to create [prepared statement] P if P was
  3796 ** created by [sqlite3_prepare_v2()], [sqlite3_prepare_v3()],
  3797 ** [sqlite3_prepare16_v2()], or [sqlite3_prepare16_v3()].
  3798 ** ^The sqlite3_expanded_sql(P) interface returns a pointer to a UTF-8
  3799 ** string containing the SQL text of prepared statement P with
  3800 ** [bound parameters] expanded.
  3801 ** ^The sqlite3_normalized_sql(P) interface returns a pointer to a UTF-8
  3802 ** string containing the normalized SQL text of prepared statement P.  The
  3803 ** semantics used to normalize a SQL statement are unspecified and subject
  3804 ** to change.  At a minimum, literal values will be replaced with suitable
  3805 ** placeholders.
  3806 **
  3807 ** ^(For example, if a prepared statement is created using the SQL
  3808 ** text "SELECT $abc,:xyz" and if parameter $abc is bound to integer 2345
  3809 ** and parameter :xyz is unbound, then sqlite3_sql() will return
  3810 ** the original string, "SELECT $abc,:xyz" but sqlite3_expanded_sql()
  3811 ** will return "SELECT 2345,NULL".)^
  3812 **
  3813 ** ^The sqlite3_expanded_sql() interface returns NULL if insufficient memory
  3814 ** is available to hold the result, or if the result would exceed the
  3815 ** the maximum string length determined by the [SQLITE_LIMIT_LENGTH].
  3816 **
  3817 ** ^The [SQLITE_TRACE_SIZE_LIMIT] compile-time option limits the size of
  3818 ** bound parameter expansions.  ^The [SQLITE_OMIT_TRACE] compile-time
  3819 ** option causes sqlite3_expanded_sql() to always return NULL.
  3820 **
  3821 ** ^The strings returned by sqlite3_sql(P) and sqlite3_normalized_sql(P)
  3822 ** are managed by SQLite and are automatically freed when the prepared
  3823 ** statement is finalized.
  3824 ** ^The string returned by sqlite3_expanded_sql(P), on the other hand,
  3825 ** is obtained from [sqlite3_malloc()] and must be free by the application
  3826 ** by passing it to [sqlite3_free()].
  3827 */
  3828 SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt);
  3829 SQLITE_API char *sqlite3_expanded_sql(sqlite3_stmt *pStmt);
  3830 SQLITE_API const char *sqlite3_normalized_sql(sqlite3_stmt *pStmt);
  3831 
  3832 /*
  3833 ** CAPI3REF: Determine If An SQL Statement Writes The Database
  3834 ** METHOD: sqlite3_stmt
  3835 **
  3836 ** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if
  3837 ** and only if the [prepared statement] X makes no direct changes to
  3838 ** the content of the database file.
  3839 **
  3840 ** Note that [application-defined SQL functions] or
  3841 ** [virtual tables] might change the database indirectly as a side effect.  
  3842 ** ^(For example, if an application defines a function "eval()" that 
  3843 ** calls [sqlite3_exec()], then the following SQL statement would
  3844 ** change the database file through side-effects:
  3845 **
  3846 ** <blockquote><pre>
  3847 **    SELECT eval('DELETE FROM t1') FROM t2;
  3848 ** </pre></blockquote>
  3849 **
  3850 ** But because the [SELECT] statement does not change the database file
  3851 ** directly, sqlite3_stmt_readonly() would still return true.)^
  3852 **
  3853 ** ^Transaction control statements such as [BEGIN], [COMMIT], [ROLLBACK],
  3854 ** [SAVEPOINT], and [RELEASE] cause sqlite3_stmt_readonly() to return true,
  3855 ** since the statements themselves do not actually modify the database but
  3856 ** rather they control the timing of when other statements modify the 
  3857 ** database.  ^The [ATTACH] and [DETACH] statements also cause
  3858 ** sqlite3_stmt_readonly() to return true since, while those statements
  3859 ** change the configuration of a database connection, they do not make 
  3860 ** changes to the content of the database files on disk.
  3861 ** ^The sqlite3_stmt_readonly() interface returns true for [BEGIN] since
  3862 ** [BEGIN] merely sets internal flags, but the [BEGIN|BEGIN IMMEDIATE] and
  3863 ** [BEGIN|BEGIN EXCLUSIVE] commands do touch the database and so
  3864 ** sqlite3_stmt_readonly() returns false for those commands.
  3865 */
  3866 SQLITE_API int sqlite3_stmt_readonly(sqlite3_stmt *pStmt);
  3867 
  3868 /*
  3869 ** CAPI3REF: Determine If A Prepared Statement Has Been Reset
  3870 ** METHOD: sqlite3_stmt
  3871 **
  3872 ** ^The sqlite3_stmt_busy(S) interface returns true (non-zero) if the
  3873 ** [prepared statement] S has been stepped at least once using 
  3874 ** [sqlite3_step(S)] but has neither run to completion (returned
  3875 ** [SQLITE_DONE] from [sqlite3_step(S)]) nor
  3876 ** been reset using [sqlite3_reset(S)].  ^The sqlite3_stmt_busy(S)
  3877 ** interface returns false if S is a NULL pointer.  If S is not a 
  3878 ** NULL pointer and is not a pointer to a valid [prepared statement]
  3879 ** object, then the behavior is undefined and probably undesirable.
  3880 **
  3881 ** This interface can be used in combination [sqlite3_next_stmt()]
  3882 ** to locate all prepared statements associated with a database 
  3883 ** connection that are in need of being reset.  This can be used,
  3884 ** for example, in diagnostic routines to search for prepared 
  3885 ** statements that are holding a transaction open.
  3886 */
  3887 SQLITE_API int sqlite3_stmt_busy(sqlite3_stmt*);
  3888 
  3889 /*
  3890 ** CAPI3REF: Dynamically Typed Value Object
  3891 ** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
  3892 **
  3893 ** SQLite uses the sqlite3_value object to represent all values
  3894 ** that can be stored in a database table. SQLite uses dynamic typing
  3895 ** for the values it stores.  ^Values stored in sqlite3_value objects
  3896 ** can be integers, floating point values, strings, BLOBs, or NULL.
  3897 **
  3898 ** An sqlite3_value object may be either "protected" or "unprotected".
  3899 ** Some interfaces require a protected sqlite3_value.  Other interfaces
  3900 ** will accept either a protected or an unprotected sqlite3_value.
  3901 ** Every interface that accepts sqlite3_value arguments specifies
  3902 ** whether or not it requires a protected sqlite3_value.  The
  3903 ** [sqlite3_value_dup()] interface can be used to construct a new 
  3904 ** protected sqlite3_value from an unprotected sqlite3_value.
  3905 **
  3906 ** The terms "protected" and "unprotected" refer to whether or not
  3907 ** a mutex is held.  An internal mutex is held for a protected
  3908 ** sqlite3_value object but no mutex is held for an unprotected
  3909 ** sqlite3_value object.  If SQLite is compiled to be single-threaded
  3910 ** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
  3911 ** or if SQLite is run in one of reduced mutex modes 
  3912 ** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
  3913 ** then there is no distinction between protected and unprotected
  3914 ** sqlite3_value objects and they can be used interchangeably.  However,
  3915 ** for maximum code portability it is recommended that applications
  3916 ** still make the distinction between protected and unprotected
  3917 ** sqlite3_value objects even when not strictly required.
  3918 **
  3919 ** ^The sqlite3_value objects that are passed as parameters into the
  3920 ** implementation of [application-defined SQL functions] are protected.
  3921 ** ^The sqlite3_value object returned by
  3922 ** [sqlite3_column_value()] is unprotected.
  3923 ** Unprotected sqlite3_value objects may only be used as arguments
  3924 ** to [sqlite3_result_value()], [sqlite3_bind_value()], and
  3925 ** [sqlite3_value_dup()].
  3926 ** The [sqlite3_value_blob | sqlite3_value_type()] family of
  3927 ** interfaces require protected sqlite3_value objects.
  3928 */
  3929 typedef struct sqlite3_value sqlite3_value;
  3930 
  3931 /*
  3932 ** CAPI3REF: SQL Function Context Object
  3933 **
  3934 ** The context in which an SQL function executes is stored in an
  3935 ** sqlite3_context object.  ^A pointer to an sqlite3_context object
  3936 ** is always first parameter to [application-defined SQL functions].
  3937 ** The application-defined SQL function implementation will pass this
  3938 ** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
  3939 ** [sqlite3_aggregate_context()], [sqlite3_user_data()],
  3940 ** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
  3941 ** and/or [sqlite3_set_auxdata()].
  3942 */
  3943 typedef struct sqlite3_context sqlite3_context;
  3944 
  3945 /*
  3946 ** CAPI3REF: Binding Values To Prepared Statements
  3947 ** KEYWORDS: {host parameter} {host parameters} {host parameter name}
  3948 ** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
  3949 ** METHOD: sqlite3_stmt
  3950 **
  3951 ** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants,
  3952 ** literals may be replaced by a [parameter] that matches one of following
  3953 ** templates:
  3954 **
  3955 ** <ul>
  3956 ** <li>  ?
  3957 ** <li>  ?NNN
  3958 ** <li>  :VVV
  3959 ** <li>  @VVV
  3960 ** <li>  $VVV
  3961 ** </ul>
  3962 **
  3963 ** In the templates above, NNN represents an integer literal,
  3964 ** and VVV represents an alphanumeric identifier.)^  ^The values of these
  3965 ** parameters (also called "host parameter names" or "SQL parameters")
  3966 ** can be set using the sqlite3_bind_*() routines defined here.
  3967 **
  3968 ** ^The first argument to the sqlite3_bind_*() routines is always
  3969 ** a pointer to the [sqlite3_stmt] object returned from
  3970 ** [sqlite3_prepare_v2()] or its variants.
  3971 **
  3972 ** ^The second argument is the index of the SQL parameter to be set.
  3973 ** ^The leftmost SQL parameter has an index of 1.  ^When the same named
  3974 ** SQL parameter is used more than once, second and subsequent
  3975 ** occurrences have the same index as the first occurrence.
  3976 ** ^The index for named parameters can be looked up using the
  3977 ** [sqlite3_bind_parameter_index()] API if desired.  ^The index
  3978 ** for "?NNN" parameters is the value of NNN.
  3979 ** ^The NNN value must be between 1 and the [sqlite3_limit()]
  3980 ** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
  3981 **
  3982 ** ^The third argument is the value to bind to the parameter.
  3983 ** ^If the third parameter to sqlite3_bind_text() or sqlite3_bind_text16()
  3984 ** or sqlite3_bind_blob() is a NULL pointer then the fourth parameter
  3985 ** is ignored and the end result is the same as sqlite3_bind_null().
  3986 **
  3987 ** ^(In those routines that have a fourth argument, its value is the
  3988 ** number of bytes in the parameter.  To be clear: the value is the
  3989 ** number of <u>bytes</u> in the value, not the number of characters.)^
  3990 ** ^If the fourth parameter to sqlite3_bind_text() or sqlite3_bind_text16()
  3991 ** is negative, then the length of the string is
  3992 ** the number of bytes up to the first zero terminator.
  3993 ** If the fourth parameter to sqlite3_bind_blob() is negative, then
  3994 ** the behavior is undefined.
  3995 ** If a non-negative fourth parameter is provided to sqlite3_bind_text()
  3996 ** or sqlite3_bind_text16() or sqlite3_bind_text64() then
  3997 ** that parameter must be the byte offset
  3998 ** where the NUL terminator would occur assuming the string were NUL
  3999 ** terminated.  If any NUL characters occur at byte offsets less than 
  4000 ** the value of the fourth parameter then the resulting string value will
  4001 ** contain embedded NULs.  The result of expressions involving strings
  4002 ** with embedded NULs is undefined.
  4003 **
  4004 ** ^The fifth argument to the BLOB and string binding interfaces
  4005 ** is a destructor used to dispose of the BLOB or
  4006 ** string after SQLite has finished with it.  ^The destructor is called
  4007 ** to dispose of the BLOB or string even if the call to bind API fails.
  4008 ** ^If the fifth argument is
  4009 ** the special value [SQLITE_STATIC], then SQLite assumes that the
  4010 ** information is in static, unmanaged space and does not need to be freed.
  4011 ** ^If the fifth argument has the value [SQLITE_TRANSIENT], then
  4012 ** SQLite makes its own private copy of the data immediately, before
  4013 ** the sqlite3_bind_*() routine returns.
  4014 **
  4015 ** ^The sixth argument to sqlite3_bind_text64() must be one of
  4016 ** [SQLITE_UTF8], [SQLITE_UTF16], [SQLITE_UTF16BE], or [SQLITE_UTF16LE]
  4017 ** to specify the encoding of the text in the third parameter.  If
  4018 ** the sixth argument to sqlite3_bind_text64() is not one of the
  4019 ** allowed values shown above, or if the text encoding is different
  4020 ** from the encoding specified by the sixth parameter, then the behavior
  4021 ** is undefined.
  4022 **
  4023 ** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
  4024 ** is filled with zeroes.  ^A zeroblob uses a fixed amount of memory
  4025 ** (just an integer to hold its size) while it is being processed.
  4026 ** Zeroblobs are intended to serve as placeholders for BLOBs whose
  4027 ** content is later written using
  4028 ** [sqlite3_blob_open | incremental BLOB I/O] routines.
  4029 ** ^A negative value for the zeroblob results in a zero-length BLOB.
  4030 **
  4031 ** ^The sqlite3_bind_pointer(S,I,P,T,D) routine causes the I-th parameter in
  4032 ** [prepared statement] S to have an SQL value of NULL, but to also be
  4033 ** associated with the pointer P of type T.  ^D is either a NULL pointer or
  4034 ** a pointer to a destructor function for P. ^SQLite will invoke the
  4035 ** destructor D with a single argument of P when it is finished using
  4036 ** P.  The T parameter should be a static string, preferably a string
  4037 ** literal. The sqlite3_bind_pointer() routine is part of the
  4038 ** [pointer passing interface] added for SQLite 3.20.0.
  4039 **
  4040 ** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer
  4041 ** for the [prepared statement] or with a prepared statement for which
  4042 ** [sqlite3_step()] has been called more recently than [sqlite3_reset()],
  4043 ** then the call will return [SQLITE_MISUSE].  If any sqlite3_bind_()
  4044 ** routine is passed a [prepared statement] that has been finalized, the
  4045 ** result is undefined and probably harmful.
  4046 **
  4047 ** ^Bindings are not cleared by the [sqlite3_reset()] routine.
  4048 ** ^Unbound parameters are interpreted as NULL.
  4049 **
  4050 ** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an
  4051 ** [error code] if anything goes wrong.
  4052 ** ^[SQLITE_TOOBIG] might be returned if the size of a string or BLOB
  4053 ** exceeds limits imposed by [sqlite3_limit]([SQLITE_LIMIT_LENGTH]) or
  4054 ** [SQLITE_MAX_LENGTH].
  4055 ** ^[SQLITE_RANGE] is returned if the parameter
  4056 ** index is out of range.  ^[SQLITE_NOMEM] is returned if malloc() fails.
  4057 **
  4058 ** See also: [sqlite3_bind_parameter_count()],
  4059 ** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
  4060 */
  4061 SQLITE_API int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
  4062 SQLITE_API int sqlite3_bind_blob64(sqlite3_stmt*, int, const void*, sqlite3_uint64,
  4063                         void(*)(void*));
  4064 SQLITE_API int sqlite3_bind_double(sqlite3_stmt*, int, double);
  4065 SQLITE_API int sqlite3_bind_int(sqlite3_stmt*, int, int);
  4066 SQLITE_API int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);
  4067 SQLITE_API int sqlite3_bind_null(sqlite3_stmt*, int);
  4068 SQLITE_API int sqlite3_bind_text(sqlite3_stmt*,int,const char*,int,void(*)(void*));
  4069 SQLITE_API int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
  4070 SQLITE_API int sqlite3_bind_text64(sqlite3_stmt*, int, const char*, sqlite3_uint64,
  4071                          void(*)(void*), unsigned char encoding);
  4072 SQLITE_API int sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*);
  4073 SQLITE_API int sqlite3_bind_pointer(sqlite3_stmt*, int, void*, const char*,void(*)(void*));
  4074 SQLITE_API int sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n);
  4075 SQLITE_API int sqlite3_bind_zeroblob64(sqlite3_stmt*, int, sqlite3_uint64);
  4076 
  4077 /*
  4078 ** CAPI3REF: Number Of SQL Parameters
  4079 ** METHOD: sqlite3_stmt
  4080 **
  4081 ** ^This routine can be used to find the number of [SQL parameters]
  4082 ** in a [prepared statement].  SQL parameters are tokens of the
  4083 ** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
  4084 ** placeholders for values that are [sqlite3_bind_blob | bound]
  4085 ** to the parameters at a later time.
  4086 **
  4087 ** ^(This routine actually returns the index of the largest (rightmost)
  4088 ** parameter. For all forms except ?NNN, this will correspond to the
  4089 ** number of unique parameters.  If parameters of the ?NNN form are used,
  4090 ** there may be gaps in the list.)^
  4091 **
  4092 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  4093 ** [sqlite3_bind_parameter_name()], and
  4094 ** [sqlite3_bind_parameter_index()].
  4095 */
  4096 SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt*);
  4097 
  4098 /*
  4099 ** CAPI3REF: Name Of A Host Parameter
  4100 ** METHOD: sqlite3_stmt
  4101 **
  4102 ** ^The sqlite3_bind_parameter_name(P,N) interface returns
  4103 ** the name of the N-th [SQL parameter] in the [prepared statement] P.
  4104 ** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
  4105 ** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
  4106 ** respectively.
  4107 ** In other words, the initial ":" or "$" or "@" or "?"
  4108 ** is included as part of the name.)^
  4109 ** ^Parameters of the form "?" without a following integer have no name
  4110 ** and are referred to as "nameless" or "anonymous parameters".
  4111 **
  4112 ** ^The first host parameter has an index of 1, not 0.
  4113 **
  4114 ** ^If the value N is out of range or if the N-th parameter is
  4115 ** nameless, then NULL is returned.  ^The returned string is
  4116 ** always in UTF-8 encoding even if the named parameter was
  4117 ** originally specified as UTF-16 in [sqlite3_prepare16()],
  4118 ** [sqlite3_prepare16_v2()], or [sqlite3_prepare16_v3()].
  4119 **
  4120 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  4121 ** [sqlite3_bind_parameter_count()], and
  4122 ** [sqlite3_bind_parameter_index()].
  4123 */
  4124 SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt*, int);
  4125 
  4126 /*
  4127 ** CAPI3REF: Index Of A Parameter With A Given Name
  4128 ** METHOD: sqlite3_stmt
  4129 **
  4130 ** ^Return the index of an SQL parameter given its name.  ^The
  4131 ** index value returned is suitable for use as the second
  4132 ** parameter to [sqlite3_bind_blob|sqlite3_bind()].  ^A zero
  4133 ** is returned if no matching parameter is found.  ^The parameter
  4134 ** name must be given in UTF-8 even if the original statement
  4135 ** was prepared from UTF-16 text using [sqlite3_prepare16_v2()] or
  4136 ** [sqlite3_prepare16_v3()].
  4137 **
  4138 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  4139 ** [sqlite3_bind_parameter_count()], and
  4140 ** [sqlite3_bind_parameter_name()].
  4141 */
  4142 SQLITE_API int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);
  4143 
  4144 /*
  4145 ** CAPI3REF: Reset All Bindings On A Prepared Statement
  4146 ** METHOD: sqlite3_stmt
  4147 **
  4148 ** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset
  4149 ** the [sqlite3_bind_blob | bindings] on a [prepared statement].
  4150 ** ^Use this routine to reset all host parameters to NULL.
  4151 */
  4152 SQLITE_API int sqlite3_clear_bindings(sqlite3_stmt*);
  4153 
  4154 /*
  4155 ** CAPI3REF: Number Of Columns In A Result Set
  4156 ** METHOD: sqlite3_stmt
  4157 **
  4158 ** ^Return the number of columns in the result set returned by the
  4159 ** [prepared statement]. ^If this routine returns 0, that means the 
  4160 ** [prepared statement] returns no data (for example an [UPDATE]).
  4161 ** ^However, just because this routine returns a positive number does not
  4162 ** mean that one or more rows of data will be returned.  ^A SELECT statement
  4163 ** will always have a positive sqlite3_column_count() but depending on the
  4164 ** WHERE clause constraints and the table content, it might return no rows.
  4165 **
  4166 ** See also: [sqlite3_data_count()]
  4167 */
  4168 SQLITE_API int sqlite3_column_count(sqlite3_stmt *pStmt);
  4169 
  4170 /*
  4171 ** CAPI3REF: Column Names In A Result Set
  4172 ** METHOD: sqlite3_stmt
  4173 **
  4174 ** ^These routines return the name assigned to a particular column
  4175 ** in the result set of a [SELECT] statement.  ^The sqlite3_column_name()
  4176 ** interface returns a pointer to a zero-terminated UTF-8 string
  4177 ** and sqlite3_column_name16() returns a pointer to a zero-terminated
  4178 ** UTF-16 string.  ^The first parameter is the [prepared statement]
  4179 ** that implements the [SELECT] statement. ^The second parameter is the
  4180 ** column number.  ^The leftmost column is number 0.
  4181 **
  4182 ** ^The returned string pointer is valid until either the [prepared statement]
  4183 ** is destroyed by [sqlite3_finalize()] or until the statement is automatically
  4184 ** reprepared by the first call to [sqlite3_step()] for a particular run
  4185 ** or until the next call to
  4186 ** sqlite3_column_name() or sqlite3_column_name16() on the same column.
  4187 **
  4188 ** ^If sqlite3_malloc() fails during the processing of either routine
  4189 ** (for example during a conversion from UTF-8 to UTF-16) then a
  4190 ** NULL pointer is returned.
  4191 **
  4192 ** ^The name of a result column is the value of the "AS" clause for
  4193 ** that column, if there is an AS clause.  If there is no AS clause
  4194 ** then the name of the column is unspecified and may change from
  4195 ** one release of SQLite to the next.
  4196 */
  4197 SQLITE_API const char *sqlite3_column_name(sqlite3_stmt*, int N);
  4198 SQLITE_API const void *sqlite3_column_name16(sqlite3_stmt*, int N);
  4199 
  4200 /*
  4201 ** CAPI3REF: Source Of Data In A Query Result
  4202 ** METHOD: sqlite3_stmt
  4203 **
  4204 ** ^These routines provide a means to determine the database, table, and
  4205 ** table column that is the origin of a particular result column in
  4206 ** [SELECT] statement.
  4207 ** ^The name of the database or table or column can be returned as
  4208 ** either a UTF-8 or UTF-16 string.  ^The _database_ routines return
  4209 ** the database name, the _table_ routines return the table name, and
  4210 ** the origin_ routines return the column name.
  4211 ** ^The returned string is valid until the [prepared statement] is destroyed
  4212 ** using [sqlite3_finalize()] or until the statement is automatically
  4213 ** reprepared by the first call to [sqlite3_step()] for a particular run
  4214 ** or until the same information is requested
  4215 ** again in a different encoding.
  4216 **
  4217 ** ^The names returned are the original un-aliased names of the
  4218 ** database, table, and column.
  4219 **
  4220 ** ^The first argument to these interfaces is a [prepared statement].
  4221 ** ^These functions return information about the Nth result column returned by
  4222 ** the statement, where N is the second function argument.
  4223 ** ^The left-most column is column 0 for these routines.
  4224 **
  4225 ** ^If the Nth column returned by the statement is an expression or
  4226 ** subquery and is not a column value, then all of these functions return
  4227 ** NULL.  ^These routine might also return NULL if a memory allocation error
  4228 ** occurs.  ^Otherwise, they return the name of the attached database, table,
  4229 ** or column that query result column was extracted from.
  4230 **
  4231 ** ^As with all other SQLite APIs, those whose names end with "16" return
  4232 ** UTF-16 encoded strings and the other functions return UTF-8.
  4233 **
  4234 ** ^These APIs are only available if the library was compiled with the
  4235 ** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol.
  4236 **
  4237 ** If two or more threads call one or more of these routines against the same
  4238 ** prepared statement and column at the same time then the results are
  4239 ** undefined.
  4240 **
  4241 ** If two or more threads call one or more
  4242 ** [sqlite3_column_database_name | column metadata interfaces]
  4243 ** for the same [prepared statement] and result column
  4244 ** at the same time then the results are undefined.
  4245 */
  4246 SQLITE_API const char *sqlite3_column_database_name(sqlite3_stmt*,int);
  4247 SQLITE_API const void *sqlite3_column_database_name16(sqlite3_stmt*,int);
  4248 SQLITE_API const char *sqlite3_column_table_name(sqlite3_stmt*,int);
  4249 SQLITE_API const void *sqlite3_column_table_name16(sqlite3_stmt*,int);
  4250 SQLITE_API const char *sqlite3_column_origin_name(sqlite3_stmt*,int);
  4251 SQLITE_API const void *sqlite3_column_origin_name16(sqlite3_stmt*,int);
  4252 
  4253 /*
  4254 ** CAPI3REF: Declared Datatype Of A Query Result
  4255 ** METHOD: sqlite3_stmt
  4256 **
  4257 ** ^(The first parameter is a [prepared statement].
  4258 ** If this statement is a [SELECT] statement and the Nth column of the
  4259 ** returned result set of that [SELECT] is a table column (not an
  4260 ** expression or subquery) then the declared type of the table
  4261 ** column is returned.)^  ^If the Nth column of the result set is an
  4262 ** expression or subquery, then a NULL pointer is returned.
  4263 ** ^The returned string is always UTF-8 encoded.
  4264 **
  4265 ** ^(For example, given the database schema:
  4266 **
  4267 ** CREATE TABLE t1(c1 VARIANT);
  4268 **
  4269 ** and the following statement to be compiled:
  4270 **
  4271 ** SELECT c1 + 1, c1 FROM t1;
  4272 **
  4273 ** this routine would return the string "VARIANT" for the second result
  4274 ** column (i==1), and a NULL pointer for the first result column (i==0).)^
  4275 **
  4276 ** ^SQLite uses dynamic run-time typing.  ^So just because a column
  4277 ** is declared to contain a particular type does not mean that the
  4278 ** data stored in that column is of the declared type.  SQLite is
  4279 ** strongly typed, but the typing is dynamic not static.  ^Type
  4280 ** is associated with individual values, not with the containers
  4281 ** used to hold those values.
  4282 */
  4283 SQLITE_API const char *sqlite3_column_decltype(sqlite3_stmt*,int);
  4284 SQLITE_API const void *sqlite3_column_decltype16(sqlite3_stmt*,int);
  4285 
  4286 /*
  4287 ** CAPI3REF: Evaluate An SQL Statement
  4288 ** METHOD: sqlite3_stmt
  4289 **
  4290 ** After a [prepared statement] has been prepared using any of
  4291 ** [sqlite3_prepare_v2()], [sqlite3_prepare_v3()], [sqlite3_prepare16_v2()],
  4292 ** or [sqlite3_prepare16_v3()] or one of the legacy
  4293 ** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
  4294 ** must be called one or more times to evaluate the statement.
  4295 **
  4296 ** The details of the behavior of the sqlite3_step() interface depend
  4297 ** on whether the statement was prepared using the newer "vX" interfaces
  4298 ** [sqlite3_prepare_v3()], [sqlite3_prepare_v2()], [sqlite3_prepare16_v3()],
  4299 ** [sqlite3_prepare16_v2()] or the older legacy
  4300 ** interfaces [sqlite3_prepare()] and [sqlite3_prepare16()].  The use of the
  4301 ** new "vX" interface is recommended for new applications but the legacy
  4302 ** interface will continue to be supported.
  4303 **
  4304 ** ^In the legacy interface, the return value will be either [SQLITE_BUSY],
  4305 ** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
  4306 ** ^With the "v2" interface, any of the other [result codes] or
  4307 ** [extended result codes] might be returned as well.
  4308 **
  4309 ** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
  4310 ** database locks it needs to do its job.  ^If the statement is a [COMMIT]
  4311 ** or occurs outside of an explicit transaction, then you can retry the
  4312 ** statement.  If the statement is not a [COMMIT] and occurs within an
  4313 ** explicit transaction then you should rollback the transaction before
  4314 ** continuing.
  4315 **
  4316 ** ^[SQLITE_DONE] means that the statement has finished executing
  4317 ** successfully.  sqlite3_step() should not be called again on this virtual
  4318 ** machine without first calling [sqlite3_reset()] to reset the virtual
  4319 ** machine back to its initial state.
  4320 **
  4321 ** ^If the SQL statement being executed returns any data, then [SQLITE_ROW]
  4322 ** is returned each time a new row of data is ready for processing by the
  4323 ** caller. The values may be accessed using the [column access functions].
  4324 ** sqlite3_step() is called again to retrieve the next row of data.
  4325 **
  4326 ** ^[SQLITE_ERROR] means that a run-time error (such as a constraint
  4327 ** violation) has occurred.  sqlite3_step() should not be called again on
  4328 ** the VM. More information may be found by calling [sqlite3_errmsg()].
  4329 ** ^With the legacy interface, a more specific error code (for example,
  4330 ** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
  4331 ** can be obtained by calling [sqlite3_reset()] on the
  4332 ** [prepared statement].  ^In the "v2" interface,
  4333 ** the more specific error code is returned directly by sqlite3_step().
  4334 **
  4335 ** [SQLITE_MISUSE] means that the this routine was called inappropriately.
  4336 ** Perhaps it was called on a [prepared statement] that has
  4337 ** already been [sqlite3_finalize | finalized] or on one that had
  4338 ** previously returned [SQLITE_ERROR] or [SQLITE_DONE].  Or it could
  4339 ** be the case that the same database connection is being used by two or
  4340 ** more threads at the same moment in time.
  4341 **
  4342 ** For all versions of SQLite up to and including 3.6.23.1, a call to
  4343 ** [sqlite3_reset()] was required after sqlite3_step() returned anything
  4344 ** other than [SQLITE_ROW] before any subsequent invocation of
  4345 ** sqlite3_step().  Failure to reset the prepared statement using 
  4346 ** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
  4347 ** sqlite3_step().  But after [version 3.6.23.1] ([dateof:3.6.23.1],
  4348 ** sqlite3_step() began
  4349 ** calling [sqlite3_reset()] automatically in this circumstance rather
  4350 ** than returning [SQLITE_MISUSE].  This is not considered a compatibility
  4351 ** break because any application that ever receives an SQLITE_MISUSE error
  4352 ** is broken by definition.  The [SQLITE_OMIT_AUTORESET] compile-time option
  4353 ** can be used to restore the legacy behavior.
  4354 **
  4355 ** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
  4356 ** API always returns a generic error code, [SQLITE_ERROR], following any
  4357 ** error other than [SQLITE_BUSY] and [SQLITE_MISUSE].  You must call
  4358 ** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
  4359 ** specific [error codes] that better describes the error.
  4360 ** We admit that this is a goofy design.  The problem has been fixed
  4361 ** with the "v2" interface.  If you prepare all of your SQL statements
  4362 ** using [sqlite3_prepare_v3()] or [sqlite3_prepare_v2()]
  4363 ** or [sqlite3_prepare16_v2()] or [sqlite3_prepare16_v3()] instead
  4364 ** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
  4365 ** then the more specific [error codes] are returned directly
  4366 ** by sqlite3_step().  The use of the "vX" interfaces is recommended.
  4367 */
  4368 SQLITE_API int sqlite3_step(sqlite3_stmt*);
  4369 
  4370 /*
  4371 ** CAPI3REF: Number of columns in a result set
  4372 ** METHOD: sqlite3_stmt
  4373 **
  4374 ** ^The sqlite3_data_count(P) interface returns the number of columns in the
  4375 ** current row of the result set of [prepared statement] P.
  4376 ** ^If prepared statement P does not have results ready to return
  4377 ** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
  4378 ** interfaces) then sqlite3_data_count(P) returns 0.
  4379 ** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
  4380 ** ^The sqlite3_data_count(P) routine returns 0 if the previous call to
  4381 ** [sqlite3_step](P) returned [SQLITE_DONE].  ^The sqlite3_data_count(P)
  4382 ** will return non-zero if previous call to [sqlite3_step](P) returned
  4383 ** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]
  4384 ** where it always returns zero since each step of that multi-step
  4385 ** pragma returns 0 columns of data.
  4386 **
  4387 ** See also: [sqlite3_column_count()]
  4388 */
  4389 SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt);
  4390 
  4391 /*
  4392 ** CAPI3REF: Fundamental Datatypes
  4393 ** KEYWORDS: SQLITE_TEXT
  4394 **
  4395 ** ^(Every value in SQLite has one of five fundamental datatypes:
  4396 **
  4397 ** <ul>
  4398 ** <li> 64-bit signed integer
  4399 ** <li> 64-bit IEEE floating point number
  4400 ** <li> string
  4401 ** <li> BLOB
  4402 ** <li> NULL
  4403 ** </ul>)^
  4404 **
  4405 ** These constants are codes for each of those types.
  4406 **
  4407 ** Note that the SQLITE_TEXT constant was also used in SQLite version 2
  4408 ** for a completely different meaning.  Software that links against both
  4409 ** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
  4410 ** SQLITE_TEXT.
  4411 */
  4412 #define SQLITE_INTEGER  1
  4413 #define SQLITE_FLOAT    2
  4414 #define SQLITE_BLOB     4
  4415 #define SQLITE_NULL     5
  4416 #ifdef SQLITE_TEXT
  4417 # undef SQLITE_TEXT
  4418 #else
  4419 # define SQLITE_TEXT     3
  4420 #endif
  4421 #define SQLITE3_TEXT     3
  4422 
  4423 /*
  4424 ** CAPI3REF: Result Values From A Query
  4425 ** KEYWORDS: {column access functions}
  4426 ** METHOD: sqlite3_stmt
  4427 **
  4428 ** <b>Summary:</b>
  4429 ** <blockquote><table border=0 cellpadding=0 cellspacing=0>
  4430 ** <tr><td><b>sqlite3_column_blob</b><td>&rarr;<td>BLOB result
  4431 ** <tr><td><b>sqlite3_column_double</b><td>&rarr;<td>REAL result
  4432 ** <tr><td><b>sqlite3_column_int</b><td>&rarr;<td>32-bit INTEGER result
  4433 ** <tr><td><b>sqlite3_column_int64</b><td>&rarr;<td>64-bit INTEGER result
  4434 ** <tr><td><b>sqlite3_column_text</b><td>&rarr;<td>UTF-8 TEXT result
  4435 ** <tr><td><b>sqlite3_column_text16</b><td>&rarr;<td>UTF-16 TEXT result
  4436 ** <tr><td><b>sqlite3_column_value</b><td>&rarr;<td>The result as an 
  4437 ** [sqlite3_value|unprotected sqlite3_value] object.
  4438 ** <tr><td>&nbsp;<td>&nbsp;<td>&nbsp;
  4439 ** <tr><td><b>sqlite3_column_bytes</b><td>&rarr;<td>Size of a BLOB
  4440 ** or a UTF-8 TEXT result in bytes
  4441 ** <tr><td><b>sqlite3_column_bytes16&nbsp;&nbsp;</b>
  4442 ** <td>&rarr;&nbsp;&nbsp;<td>Size of UTF-16
  4443 ** TEXT in bytes
  4444 ** <tr><td><b>sqlite3_column_type</b><td>&rarr;<td>Default
  4445 ** datatype of the result
  4446 ** </table></blockquote>
  4447 **
  4448 ** <b>Details:</b>
  4449 **
  4450 ** ^These routines return information about a single column of the current
  4451 ** result row of a query.  ^In every case the first argument is a pointer
  4452 ** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
  4453 ** that was returned from [sqlite3_prepare_v2()] or one of its variants)
  4454 ** and the second argument is the index of the column for which information
  4455 ** should be returned. ^The leftmost column of the result set has the index 0.
  4456 ** ^The number of columns in the result can be determined using
  4457 ** [sqlite3_column_count()].
  4458 **
  4459 ** If the SQL statement does not currently point to a valid row, or if the
  4460 ** column index is out of range, the result is undefined.
  4461 ** These routines may only be called when the most recent call to
  4462 ** [sqlite3_step()] has returned [SQLITE_ROW] and neither
  4463 ** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
  4464 ** If any of these routines are called after [sqlite3_reset()] or
  4465 ** [sqlite3_finalize()] or after [sqlite3_step()] has returned
  4466 ** something other than [SQLITE_ROW], the results are undefined.
  4467 ** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
  4468 ** are called from a different thread while any of these routines
  4469 ** are pending, then the results are undefined.
  4470 **
  4471 ** The first six interfaces (_blob, _double, _int, _int64, _text, and _text16)
  4472 ** each return the value of a result column in a specific data format.  If
  4473 ** the result column is not initially in the requested format (for example,
  4474 ** if the query returns an integer but the sqlite3_column_text() interface
  4475 ** is used to extract the value) then an automatic type conversion is performed.
  4476 **
  4477 ** ^The sqlite3_column_type() routine returns the
  4478 ** [SQLITE_INTEGER | datatype code] for the initial data type
  4479 ** of the result column.  ^The returned value is one of [SQLITE_INTEGER],
  4480 ** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL].
  4481 ** The return value of sqlite3_column_type() can be used to decide which
  4482 ** of the first six interface should be used to extract the column value.
  4483 ** The value returned by sqlite3_column_type() is only meaningful if no
  4484 ** automatic type conversions have occurred for the value in question.  
  4485 ** After a type conversion, the result of calling sqlite3_column_type()
  4486 ** is undefined, though harmless.  Future
  4487 ** versions of SQLite may change the behavior of sqlite3_column_type()
  4488 ** following a type conversion.
  4489 **
  4490 ** If the result is a BLOB or a TEXT string, then the sqlite3_column_bytes()
  4491 ** or sqlite3_column_bytes16() interfaces can be used to determine the size
  4492 ** of that BLOB or string.
  4493 **
  4494 ** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
  4495 ** routine returns the number of bytes in that BLOB or string.
  4496 ** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts
  4497 ** the string to UTF-8 and then returns the number of bytes.
  4498 ** ^If the result is a numeric value then sqlite3_column_bytes() uses
  4499 ** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
  4500 ** the number of bytes in that string.
  4501 ** ^If the result is NULL, then sqlite3_column_bytes() returns zero.
  4502 **
  4503 ** ^If the result is a BLOB or UTF-16 string then the sqlite3_column_bytes16()
  4504 ** routine returns the number of bytes in that BLOB or string.
  4505 ** ^If the result is a UTF-8 string, then sqlite3_column_bytes16() converts
  4506 ** the string to UTF-16 and then returns the number of bytes.
  4507 ** ^If the result is a numeric value then sqlite3_column_bytes16() uses
  4508 ** [sqlite3_snprintf()] to convert that value to a UTF-16 string and returns
  4509 ** the number of bytes in that string.
  4510 ** ^If the result is NULL, then sqlite3_column_bytes16() returns zero.
  4511 **
  4512 ** ^The values returned by [sqlite3_column_bytes()] and 
  4513 ** [sqlite3_column_bytes16()] do not include the zero terminators at the end
  4514 ** of the string.  ^For clarity: the values returned by
  4515 ** [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] are the number of
  4516 ** bytes in the string, not the number of characters.
  4517 **
  4518 ** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
  4519 ** even empty strings, are always zero-terminated.  ^The return
  4520 ** value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer.
  4521 **
  4522 ** <b>Warning:</b> ^The object returned by [sqlite3_column_value()] is an
  4523 ** [unprotected sqlite3_value] object.  In a multithreaded environment,
  4524 ** an unprotected sqlite3_value object may only be used safely with
  4525 ** [sqlite3_bind_value()] and [sqlite3_result_value()].
  4526 ** If the [unprotected sqlite3_value] object returned by
  4527 ** [sqlite3_column_value()] is used in any other way, including calls
  4528 ** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
  4529 ** or [sqlite3_value_bytes()], the behavior is not threadsafe.
  4530 ** Hence, the sqlite3_column_value() interface
  4531 ** is normally only useful within the implementation of 
  4532 ** [application-defined SQL functions] or [virtual tables], not within
  4533 ** top-level application code.
  4534 **
  4535 ** The these routines may attempt to convert the datatype of the result.
  4536 ** ^For example, if the internal representation is FLOAT and a text result
  4537 ** is requested, [sqlite3_snprintf()] is used internally to perform the
  4538 ** conversion automatically.  ^(The following table details the conversions
  4539 ** that are applied:
  4540 **
  4541 ** <blockquote>
  4542 ** <table border="1">
  4543 ** <tr><th> Internal<br>Type <th> Requested<br>Type <th>  Conversion
  4544 **
  4545 ** <tr><td>  NULL    <td> INTEGER   <td> Result is 0
  4546 ** <tr><td>  NULL    <td>  FLOAT    <td> Result is 0.0
  4547 ** <tr><td>  NULL    <td>   TEXT    <td> Result is a NULL pointer
  4548 ** <tr><td>  NULL    <td>   BLOB    <td> Result is a NULL pointer
  4549 ** <tr><td> INTEGER  <td>  FLOAT    <td> Convert from integer to float
  4550 ** <tr><td> INTEGER  <td>   TEXT    <td> ASCII rendering of the integer
  4551 ** <tr><td> INTEGER  <td>   BLOB    <td> Same as INTEGER->TEXT
  4552 ** <tr><td>  FLOAT   <td> INTEGER   <td> [CAST] to INTEGER
  4553 ** <tr><td>  FLOAT   <td>   TEXT    <td> ASCII rendering of the float
  4554 ** <tr><td>  FLOAT   <td>   BLOB    <td> [CAST] to BLOB
  4555 ** <tr><td>  TEXT    <td> INTEGER   <td> [CAST] to INTEGER
  4556 ** <tr><td>  TEXT    <td>  FLOAT    <td> [CAST] to REAL
  4557 ** <tr><td>  TEXT    <td>   BLOB    <td> No change
  4558 ** <tr><td>  BLOB    <td> INTEGER   <td> [CAST] to INTEGER
  4559 ** <tr><td>  BLOB    <td>  FLOAT    <td> [CAST] to REAL
  4560 ** <tr><td>  BLOB    <td>   TEXT    <td> Add a zero terminator if needed
  4561 ** </table>
  4562 ** </blockquote>)^
  4563 **
  4564 ** Note that when type conversions occur, pointers returned by prior
  4565 ** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
  4566 ** sqlite3_column_text16() may be invalidated.
  4567 ** Type conversions and pointer invalidations might occur
  4568 ** in the following cases:
  4569 **
  4570 ** <ul>
  4571 ** <li> The initial content is a BLOB and sqlite3_column_text() or
  4572 **      sqlite3_column_text16() is called.  A zero-terminator might
  4573 **      need to be added to the string.</li>
  4574 ** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
  4575 **      sqlite3_column_text16() is called.  The content must be converted
  4576 **      to UTF-16.</li>
  4577 ** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
  4578 **      sqlite3_column_text() is called.  The content must be converted
  4579 **      to UTF-8.</li>
  4580 ** </ul>
  4581 **
  4582 ** ^Conversions between UTF-16be and UTF-16le are always done in place and do
  4583 ** not invalidate a prior pointer, though of course the content of the buffer
  4584 ** that the prior pointer references will have been modified.  Other kinds
  4585 ** of conversion are done in place when it is possible, but sometimes they
  4586 ** are not possible and in those cases prior pointers are invalidated.
  4587 **
  4588 ** The safest policy is to invoke these routines
  4589 ** in one of the following ways:
  4590 **
  4591 ** <ul>
  4592 **  <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
  4593 **  <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
  4594 **  <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
  4595 ** </ul>
  4596 **
  4597 ** In other words, you should call sqlite3_column_text(),
  4598 ** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
  4599 ** into the desired format, then invoke sqlite3_column_bytes() or
  4600 ** sqlite3_column_bytes16() to find the size of the result.  Do not mix calls
  4601 ** to sqlite3_column_text() or sqlite3_column_blob() with calls to
  4602 ** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
  4603 ** with calls to sqlite3_column_bytes().
  4604 **
  4605 ** ^The pointers returned are valid until a type conversion occurs as
  4606 ** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
  4607 ** [sqlite3_finalize()] is called.  ^The memory space used to hold strings
  4608 ** and BLOBs is freed automatically.  Do not pass the pointers returned
  4609 ** from [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
  4610 ** [sqlite3_free()].
  4611 **
  4612 ** As long as the input parameters are correct, these routines will only
  4613 ** fail if an out-of-memory error occurs during a format conversion.
  4614 ** Only the following subset of interfaces are subject to out-of-memory
  4615 ** errors:
  4616 **
  4617 ** <ul>
  4618 ** <li> sqlite3_column_blob()
  4619 ** <li> sqlite3_column_text()
  4620 ** <li> sqlite3_column_text16()
  4621 ** <li> sqlite3_column_bytes()
  4622 ** <li> sqlite3_column_bytes16()
  4623 ** </ul>
  4624 **
  4625 ** If an out-of-memory error occurs, then the return value from these
  4626 ** routines is the same as if the column had contained an SQL NULL value.
  4627 ** Valid SQL NULL returns can be distinguished from out-of-memory errors
  4628 ** by invoking the [sqlite3_errcode()] immediately after the suspect
  4629 ** return value is obtained and before any
  4630 ** other SQLite interface is called on the same [database connection].
  4631 */
  4632 SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
  4633 SQLITE_API double sqlite3_column_double(sqlite3_stmt*, int iCol);
  4634 SQLITE_API int sqlite3_column_int(sqlite3_stmt*, int iCol);
  4635 SQLITE_API sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
  4636 SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
  4637 SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
  4638 SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);
  4639 SQLITE_API int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
  4640 SQLITE_API int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
  4641 SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
  4642 
  4643 /*
  4644 ** CAPI3REF: Destroy A Prepared Statement Object
  4645 ** DESTRUCTOR: sqlite3_stmt
  4646 **
  4647 ** ^The sqlite3_finalize() function is called to delete a [prepared statement].
  4648 ** ^If the most recent evaluation of the statement encountered no errors
  4649 ** or if the statement is never been evaluated, then sqlite3_finalize() returns
  4650 ** SQLITE_OK.  ^If the most recent evaluation of statement S failed, then
  4651 ** sqlite3_finalize(S) returns the appropriate [error code] or
  4652 ** [extended error code].
  4653 **
  4654 ** ^The sqlite3_finalize(S) routine can be called at any point during
  4655 ** the life cycle of [prepared statement] S:
  4656 ** before statement S is ever evaluated, after
  4657 ** one or more calls to [sqlite3_reset()], or after any call
  4658 ** to [sqlite3_step()] regardless of whether or not the statement has
  4659 ** completed execution.
  4660 **
  4661 ** ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op.
  4662 **
  4663 ** The application must finalize every [prepared statement] in order to avoid
  4664 ** resource leaks.  It is a grievous error for the application to try to use
  4665 ** a prepared statement after it has been finalized.  Any use of a prepared
  4666 ** statement after it has been finalized can result in undefined and
  4667 ** undesirable behavior such as segfaults and heap corruption.
  4668 */
  4669 SQLITE_API int sqlite3_finalize(sqlite3_stmt *pStmt);
  4670 
  4671 /*
  4672 ** CAPI3REF: Reset A Prepared Statement Object
  4673 ** METHOD: sqlite3_stmt
  4674 **
  4675 ** The sqlite3_reset() function is called to reset a [prepared statement]
  4676 ** object back to its initial state, ready to be re-executed.
  4677 ** ^Any SQL statement variables that had values bound to them using
  4678 ** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
  4679 ** Use [sqlite3_clear_bindings()] to reset the bindings.
  4680 **
  4681 ** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S
  4682 ** back to the beginning of its program.
  4683 **
  4684 ** ^If the most recent call to [sqlite3_step(S)] for the
  4685 ** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
  4686 ** or if [sqlite3_step(S)] has never before been called on S,
  4687 ** then [sqlite3_reset(S)] returns [SQLITE_OK].
  4688 **
  4689 ** ^If the most recent call to [sqlite3_step(S)] for the
  4690 ** [prepared statement] S indicated an error, then
  4691 ** [sqlite3_reset(S)] returns an appropriate [error code].
  4692 **
  4693 ** ^The [sqlite3_reset(S)] interface does not change the values
  4694 ** of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
  4695 */
  4696 SQLITE_API int sqlite3_reset(sqlite3_stmt *pStmt);
  4697 
  4698 /*
  4699 ** CAPI3REF: Create Or Redefine SQL Functions
  4700 ** KEYWORDS: {function creation routines}
  4701 ** KEYWORDS: {application-defined SQL function}
  4702 ** KEYWORDS: {application-defined SQL functions}
  4703 ** METHOD: sqlite3
  4704 **
  4705 ** ^These functions (collectively known as "function creation routines")
  4706 ** are used to add SQL functions or aggregates or to redefine the behavior
  4707 ** of existing SQL functions or aggregates. The only differences between
  4708 ** the three "sqlite3_create_function*" routines are the text encoding 
  4709 ** expected for the second parameter (the name of the function being 
  4710 ** created) and the presence or absence of a destructor callback for
  4711 ** the application data pointer. Function sqlite3_create_window_function()
  4712 ** is similar, but allows the user to supply the extra callback functions
  4713 ** needed by [aggregate window functions].
  4714 **
  4715 ** ^The first parameter is the [database connection] to which the SQL
  4716 ** function is to be added.  ^If an application uses more than one database
  4717 ** connection then application-defined SQL functions must be added
  4718 ** to each database connection separately.
  4719 **
  4720 ** ^The second parameter is the name of the SQL function to be created or
  4721 ** redefined.  ^The length of the name is limited to 255 bytes in a UTF-8
  4722 ** representation, exclusive of the zero-terminator.  ^Note that the name
  4723 ** length limit is in UTF-8 bytes, not characters nor UTF-16 bytes.  
  4724 ** ^Any attempt to create a function with a longer name
  4725 ** will result in [SQLITE_MISUSE] being returned.
  4726 **
  4727 ** ^The third parameter (nArg)
  4728 ** is the number of arguments that the SQL function or
  4729 ** aggregate takes. ^If this parameter is -1, then the SQL function or
  4730 ** aggregate may take any number of arguments between 0 and the limit
  4731 ** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]).  If the third
  4732 ** parameter is less than -1 or greater than 127 then the behavior is
  4733 ** undefined.
  4734 **
  4735 ** ^The fourth parameter, eTextRep, specifies what
  4736 ** [SQLITE_UTF8 | text encoding] this SQL function prefers for
  4737 ** its parameters.  The application should set this parameter to
  4738 ** [SQLITE_UTF16LE] if the function implementation invokes 
  4739 ** [sqlite3_value_text16le()] on an input, or [SQLITE_UTF16BE] if the
  4740 ** implementation invokes [sqlite3_value_text16be()] on an input, or
  4741 ** [SQLITE_UTF16] if [sqlite3_value_text16()] is used, or [SQLITE_UTF8]
  4742 ** otherwise.  ^The same SQL function may be registered multiple times using
  4743 ** different preferred text encodings, with different implementations for
  4744 ** each encoding.
  4745 ** ^When multiple implementations of the same function are available, SQLite
  4746 ** will pick the one that involves the least amount of data conversion.
  4747 **
  4748 ** ^The fourth parameter may optionally be ORed with [SQLITE_DETERMINISTIC]
  4749 ** to signal that the function will always return the same result given
  4750 ** the same inputs within a single SQL statement.  Most SQL functions are
  4751 ** deterministic.  The built-in [random()] SQL function is an example of a
  4752 ** function that is not deterministic.  The SQLite query planner is able to
  4753 ** perform additional optimizations on deterministic functions, so use
  4754 ** of the [SQLITE_DETERMINISTIC] flag is recommended where possible.
  4755 **
  4756 ** ^(The fifth parameter is an arbitrary pointer.  The implementation of the
  4757 ** function can gain access to this pointer using [sqlite3_user_data()].)^
  4758 **
  4759 ** ^The sixth, seventh and eighth parameters passed to the three
  4760 ** "sqlite3_create_function*" functions, xFunc, xStep and xFinal, are
  4761 ** pointers to C-language functions that implement the SQL function or
  4762 ** aggregate. ^A scalar SQL function requires an implementation of the xFunc
  4763 ** callback only; NULL pointers must be passed as the xStep and xFinal
  4764 ** parameters. ^An aggregate SQL function requires an implementation of xStep
  4765 ** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
  4766 ** SQL function or aggregate, pass NULL pointers for all three function
  4767 ** callbacks.
  4768 **
  4769 ** ^The sixth, seventh, eighth and ninth parameters (xStep, xFinal, xValue 
  4770 ** and xInverse) passed to sqlite3_create_window_function are pointers to
  4771 ** C-language callbacks that implement the new function. xStep and xFinal
  4772 ** must both be non-NULL. xValue and xInverse may either both be NULL, in
  4773 ** which case a regular aggregate function is created, or must both be 
  4774 ** non-NULL, in which case the new function may be used as either an aggregate
  4775 ** or aggregate window function. More details regarding the implementation
  4776 ** of aggregate window functions are 
  4777 ** [user-defined window functions|available here].
  4778 **
  4779 ** ^(If the final parameter to sqlite3_create_function_v2() or
  4780 ** sqlite3_create_window_function() is not NULL, then it is destructor for
  4781 ** the application data pointer. The destructor is invoked when the function 
  4782 ** is deleted, either by being overloaded or when the database connection 
  4783 ** closes.)^ ^The destructor is also invoked if the call to 
  4784 ** sqlite3_create_function_v2() fails.  ^When the destructor callback is
  4785 ** invoked, it is passed a single argument which is a copy of the application
  4786 ** data pointer which was the fifth parameter to sqlite3_create_function_v2().
  4787 **
  4788 ** ^It is permitted to register multiple implementations of the same
  4789 ** functions with the same name but with either differing numbers of
  4790 ** arguments or differing preferred text encodings.  ^SQLite will use
  4791 ** the implementation that most closely matches the way in which the
  4792 ** SQL function is used.  ^A function implementation with a non-negative
  4793 ** nArg parameter is a better match than a function implementation with
  4794 ** a negative nArg.  ^A function where the preferred text encoding
  4795 ** matches the database encoding is a better
  4796 ** match than a function where the encoding is different.  
  4797 ** ^A function where the encoding difference is between UTF16le and UTF16be
  4798 ** is a closer match than a function where the encoding difference is
  4799 ** between UTF8 and UTF16.
  4800 **
  4801 ** ^Built-in functions may be overloaded by new application-defined functions.
  4802 **
  4803 ** ^An application-defined function is permitted to call other
  4804 ** SQLite interfaces.  However, such calls must not
  4805 ** close the database connection nor finalize or reset the prepared
  4806 ** statement in which the function is running.
  4807 */
  4808 SQLITE_API int sqlite3_create_function(
  4809   sqlite3 *db,
  4810   const char *zFunctionName,
  4811   int nArg,
  4812   int eTextRep,
  4813   void *pApp,
  4814   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4815   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4816   void (*xFinal)(sqlite3_context*)
  4817 );
  4818 SQLITE_API int sqlite3_create_function16(
  4819   sqlite3 *db,
  4820   const void *zFunctionName,
  4821   int nArg,
  4822   int eTextRep,
  4823   void *pApp,
  4824   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4825   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4826   void (*xFinal)(sqlite3_context*)
  4827 );
  4828 SQLITE_API int sqlite3_create_function_v2(
  4829   sqlite3 *db,
  4830   const char *zFunctionName,
  4831   int nArg,
  4832   int eTextRep,
  4833   void *pApp,
  4834   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4835   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4836   void (*xFinal)(sqlite3_context*),
  4837   void(*xDestroy)(void*)
  4838 );
  4839 SQLITE_API int sqlite3_create_window_function(
  4840   sqlite3 *db,
  4841   const char *zFunctionName,
  4842   int nArg,
  4843   int eTextRep,
  4844   void *pApp,
  4845   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4846   void (*xFinal)(sqlite3_context*),
  4847   void (*xValue)(sqlite3_context*),
  4848   void (*xInverse)(sqlite3_context*,int,sqlite3_value**),
  4849   void(*xDestroy)(void*)
  4850 );
  4851 
  4852 /*
  4853 ** CAPI3REF: Text Encodings
  4854 **
  4855 ** These constant define integer codes that represent the various
  4856 ** text encodings supported by SQLite.
  4857 */
  4858 #define SQLITE_UTF8           1    /* IMP: R-37514-35566 */
  4859 #define SQLITE_UTF16LE        2    /* IMP: R-03371-37637 */
  4860 #define SQLITE_UTF16BE        3    /* IMP: R-51971-34154 */
  4861 #define SQLITE_UTF16          4    /* Use native byte order */
  4862 #define SQLITE_ANY            5    /* Deprecated */
  4863 #define SQLITE_UTF16_ALIGNED  8    /* sqlite3_create_collation only */
  4864 
  4865 /*
  4866 ** CAPI3REF: Function Flags
  4867 **
  4868 ** These constants may be ORed together with the 
  4869 ** [SQLITE_UTF8 | preferred text encoding] as the fourth argument
  4870 ** to [sqlite3_create_function()], [sqlite3_create_function16()], or
  4871 ** [sqlite3_create_function_v2()].
  4872 */
  4873 #define SQLITE_DETERMINISTIC    0x800
  4874 
  4875 /*
  4876 ** CAPI3REF: Deprecated Functions
  4877 ** DEPRECATED
  4878 **
  4879 ** These functions are [deprecated].  In order to maintain
  4880 ** backwards compatibility with older code, these functions continue 
  4881 ** to be supported.  However, new applications should avoid
  4882 ** the use of these functions.  To encourage programmers to avoid
  4883 ** these functions, we will not explain what they do.
  4884 */
  4885 #ifndef SQLITE_OMIT_DEPRECATED
  4886 SQLITE_API SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*);
  4887 SQLITE_API SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*);
  4888 SQLITE_API SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);
  4889 SQLITE_API SQLITE_DEPRECATED int sqlite3_global_recover(void);
  4890 SQLITE_API SQLITE_DEPRECATED void sqlite3_thread_cleanup(void);
  4891 SQLITE_API SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),
  4892                       void*,sqlite3_int64);
  4893 #endif
  4894 
  4895 /*
  4896 ** CAPI3REF: Obtaining SQL Values
  4897 ** METHOD: sqlite3_value
  4898 **
  4899 ** <b>Summary:</b>
  4900 ** <blockquote><table border=0 cellpadding=0 cellspacing=0>
  4901 ** <tr><td><b>sqlite3_value_blob</b><td>&rarr;<td>BLOB value
  4902 ** <tr><td><b>sqlite3_value_double</b><td>&rarr;<td>REAL value
  4903 ** <tr><td><b>sqlite3_value_int</b><td>&rarr;<td>32-bit INTEGER value
  4904 ** <tr><td><b>sqlite3_value_int64</b><td>&rarr;<td>64-bit INTEGER value
  4905 ** <tr><td><b>sqlite3_value_pointer</b><td>&rarr;<td>Pointer value
  4906 ** <tr><td><b>sqlite3_value_text</b><td>&rarr;<td>UTF-8 TEXT value
  4907 ** <tr><td><b>sqlite3_value_text16</b><td>&rarr;<td>UTF-16 TEXT value in
  4908 ** the native byteorder
  4909 ** <tr><td><b>sqlite3_value_text16be</b><td>&rarr;<td>UTF-16be TEXT value
  4910 ** <tr><td><b>sqlite3_value_text16le</b><td>&rarr;<td>UTF-16le TEXT value
  4911 ** <tr><td>&nbsp;<td>&nbsp;<td>&nbsp;
  4912 ** <tr><td><b>sqlite3_value_bytes</b><td>&rarr;<td>Size of a BLOB
  4913 ** or a UTF-8 TEXT in bytes
  4914 ** <tr><td><b>sqlite3_value_bytes16&nbsp;&nbsp;</b>
  4915 ** <td>&rarr;&nbsp;&nbsp;<td>Size of UTF-16
  4916 ** TEXT in bytes
  4917 ** <tr><td><b>sqlite3_value_type</b><td>&rarr;<td>Default
  4918 ** datatype of the value
  4919 ** <tr><td><b>sqlite3_value_numeric_type&nbsp;&nbsp;</b>
  4920 ** <td>&rarr;&nbsp;&nbsp;<td>Best numeric datatype of the value
  4921 ** <tr><td><b>sqlite3_value_nochange&nbsp;&nbsp;</b>
  4922 ** <td>&rarr;&nbsp;&nbsp;<td>True if the column is unchanged in an UPDATE
  4923 ** against a virtual table.
  4924 ** </table></blockquote>
  4925 **
  4926 ** <b>Details:</b>
  4927 **
  4928 ** These routines extract type, size, and content information from
  4929 ** [protected sqlite3_value] objects.  Protected sqlite3_value objects
  4930 ** are used to pass parameter information into implementation of
  4931 ** [application-defined SQL functions] and [virtual tables].
  4932 **
  4933 ** These routines work only with [protected sqlite3_value] objects.
  4934 ** Any attempt to use these routines on an [unprotected sqlite3_value]
  4935 ** is not threadsafe.
  4936 **
  4937 ** ^These routines work just like the corresponding [column access functions]
  4938 ** except that these routines take a single [protected sqlite3_value] object
  4939 ** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
  4940 **
  4941 ** ^The sqlite3_value_text16() interface extracts a UTF-16 string
  4942 ** in the native byte-order of the host machine.  ^The
  4943 ** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
  4944 ** extract UTF-16 strings as big-endian and little-endian respectively.
  4945 **
  4946 ** ^If [sqlite3_value] object V was initialized 
  4947 ** using [sqlite3_bind_pointer(S,I,P,X,D)] or [sqlite3_result_pointer(C,P,X,D)]
  4948 ** and if X and Y are strings that compare equal according to strcmp(X,Y),
  4949 ** then sqlite3_value_pointer(V,Y) will return the pointer P.  ^Otherwise,
  4950 ** sqlite3_value_pointer(V,Y) returns a NULL. The sqlite3_bind_pointer() 
  4951 ** routine is part of the [pointer passing interface] added for SQLite 3.20.0.
  4952 **
  4953 ** ^(The sqlite3_value_type(V) interface returns the
  4954 ** [SQLITE_INTEGER | datatype code] for the initial datatype of the
  4955 ** [sqlite3_value] object V. The returned value is one of [SQLITE_INTEGER],
  4956 ** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL].)^
  4957 ** Other interfaces might change the datatype for an sqlite3_value object.
  4958 ** For example, if the datatype is initially SQLITE_INTEGER and
  4959 ** sqlite3_value_text(V) is called to extract a text value for that
  4960 ** integer, then subsequent calls to sqlite3_value_type(V) might return
  4961 ** SQLITE_TEXT.  Whether or not a persistent internal datatype conversion
  4962 ** occurs is undefined and may change from one release of SQLite to the next.
  4963 **
  4964 ** ^(The sqlite3_value_numeric_type() interface attempts to apply
  4965 ** numeric affinity to the value.  This means that an attempt is
  4966 ** made to convert the value to an integer or floating point.  If
  4967 ** such a conversion is possible without loss of information (in other
  4968 ** words, if the value is a string that looks like a number)
  4969 ** then the conversion is performed.  Otherwise no conversion occurs.
  4970 ** The [SQLITE_INTEGER | datatype] after conversion is returned.)^
  4971 **
  4972 ** ^Within the [xUpdate] method of a [virtual table], the
  4973 ** sqlite3_value_nochange(X) interface returns true if and only if
  4974 ** the column corresponding to X is unchanged by the UPDATE operation
  4975 ** that the xUpdate method call was invoked to implement and if
  4976 ** and the prior [xColumn] method call that was invoked to extracted
  4977 ** the value for that column returned without setting a result (probably
  4978 ** because it queried [sqlite3_vtab_nochange()] and found that the column
  4979 ** was unchanging).  ^Within an [xUpdate] method, any value for which
  4980 ** sqlite3_value_nochange(X) is true will in all other respects appear
  4981 ** to be a NULL value.  If sqlite3_value_nochange(X) is invoked anywhere other
  4982 ** than within an [xUpdate] method call for an UPDATE statement, then
  4983 ** the return value is arbitrary and meaningless.
  4984 **
  4985 ** Please pay particular attention to the fact that the pointer returned
  4986 ** from [sqlite3_value_blob()], [sqlite3_value_text()], or
  4987 ** [sqlite3_value_text16()] can be invalidated by a subsequent call to
  4988 ** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
  4989 ** or [sqlite3_value_text16()].
  4990 **
  4991 ** These routines must be called from the same thread as
  4992 ** the SQL function that supplied the [sqlite3_value*] parameters.
  4993 **
  4994 ** As long as the input parameter is correct, these routines can only
  4995 ** fail if an out-of-memory error occurs during a format conversion.
  4996 ** Only the following subset of interfaces are subject to out-of-memory
  4997 ** errors:
  4998 **
  4999 ** <ul>
  5000 ** <li> sqlite3_value_blob()
  5001 ** <li> sqlite3_value_text()
  5002 ** <li> sqlite3_value_text16()
  5003 ** <li> sqlite3_value_text16le()
  5004 ** <li> sqlite3_value_text16be()
  5005 ** <li> sqlite3_value_bytes()
  5006 ** <li> sqlite3_value_bytes16()
  5007 ** </ul>
  5008 **
  5009 ** If an out-of-memory error occurs, then the return value from these
  5010 ** routines is the same as if the column had contained an SQL NULL value.
  5011 ** Valid SQL NULL returns can be distinguished from out-of-memory errors
  5012 ** by invoking the [sqlite3_errcode()] immediately after the suspect
  5013 ** return value is obtained and before any
  5014 ** other SQLite interface is called on the same [database connection].
  5015 */
  5016 SQLITE_API const void *sqlite3_value_blob(sqlite3_value*);
  5017 SQLITE_API double sqlite3_value_double(sqlite3_value*);
  5018 SQLITE_API int sqlite3_value_int(sqlite3_value*);
  5019 SQLITE_API sqlite3_int64 sqlite3_value_int64(sqlite3_value*);
  5020 SQLITE_API void *sqlite3_value_pointer(sqlite3_value*, const char*);
  5021 SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value*);
  5022 SQLITE_API const void *sqlite3_value_text16(sqlite3_value*);
  5023 SQLITE_API const void *sqlite3_value_text16le(sqlite3_value*);
  5024 SQLITE_API const void *sqlite3_value_text16be(sqlite3_value*);
  5025 SQLITE_API int sqlite3_value_bytes(sqlite3_value*);
  5026 SQLITE_API int sqlite3_value_bytes16(sqlite3_value*);
  5027 SQLITE_API int sqlite3_value_type(sqlite3_value*);
  5028 SQLITE_API int sqlite3_value_numeric_type(sqlite3_value*);
  5029 SQLITE_API int sqlite3_value_nochange(sqlite3_value*);
  5030 
  5031 /*
  5032 ** CAPI3REF: Finding The Subtype Of SQL Values
  5033 ** METHOD: sqlite3_value
  5034 **
  5035 ** The sqlite3_value_subtype(V) function returns the subtype for
  5036 ** an [application-defined SQL function] argument V.  The subtype
  5037 ** information can be used to pass a limited amount of context from
  5038 ** one SQL function to another.  Use the [sqlite3_result_subtype()]
  5039 ** routine to set the subtype for the return value of an SQL function.
  5040 */
  5041 SQLITE_API unsigned int sqlite3_value_subtype(sqlite3_value*);
  5042 
  5043 /*
  5044 ** CAPI3REF: Copy And Free SQL Values
  5045 ** METHOD: sqlite3_value
  5046 **
  5047 ** ^The sqlite3_value_dup(V) interface makes a copy of the [sqlite3_value]
  5048 ** object D and returns a pointer to that copy.  ^The [sqlite3_value] returned
  5049 ** is a [protected sqlite3_value] object even if the input is not.
  5050 ** ^The sqlite3_value_dup(V) interface returns NULL if V is NULL or if a
  5051 ** memory allocation fails.
  5052 **
  5053 ** ^The sqlite3_value_free(V) interface frees an [sqlite3_value] object
  5054 ** previously obtained from [sqlite3_value_dup()].  ^If V is a NULL pointer
  5055 ** then sqlite3_value_free(V) is a harmless no-op.
  5056 */
  5057 SQLITE_API sqlite3_value *sqlite3_value_dup(const sqlite3_value*);
  5058 SQLITE_API void sqlite3_value_free(sqlite3_value*);
  5059 
  5060 /*
  5061 ** CAPI3REF: Obtain Aggregate Function Context
  5062 ** METHOD: sqlite3_context
  5063 **
  5064 ** Implementations of aggregate SQL functions use this
  5065 ** routine to allocate memory for storing their state.
  5066 **
  5067 ** ^The first time the sqlite3_aggregate_context(C,N) routine is called 
  5068 ** for a particular aggregate function, SQLite
  5069 ** allocates N of memory, zeroes out that memory, and returns a pointer
  5070 ** to the new memory. ^On second and subsequent calls to
  5071 ** sqlite3_aggregate_context() for the same aggregate function instance,
  5072 ** the same buffer is returned.  Sqlite3_aggregate_context() is normally
  5073 ** called once for each invocation of the xStep callback and then one
  5074 ** last time when the xFinal callback is invoked.  ^(When no rows match
  5075 ** an aggregate query, the xStep() callback of the aggregate function
  5076 ** implementation is never called and xFinal() is called exactly once.
  5077 ** In those cases, sqlite3_aggregate_context() might be called for the
  5078 ** first time from within xFinal().)^
  5079 **
  5080 ** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer 
  5081 ** when first called if N is less than or equal to zero or if a memory
  5082 ** allocate error occurs.
  5083 **
  5084 ** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is
  5085 ** determined by the N parameter on first successful call.  Changing the
  5086 ** value of N in subsequent call to sqlite3_aggregate_context() within
  5087 ** the same aggregate function instance will not resize the memory
  5088 ** allocation.)^  Within the xFinal callback, it is customary to set
  5089 ** N=0 in calls to sqlite3_aggregate_context(C,N) so that no 
  5090 ** pointless memory allocations occur.
  5091 **
  5092 ** ^SQLite automatically frees the memory allocated by 
  5093 ** sqlite3_aggregate_context() when the aggregate query concludes.
  5094 **
  5095 ** The first parameter must be a copy of the
  5096 ** [sqlite3_context | SQL function context] that is the first parameter
  5097 ** to the xStep or xFinal callback routine that implements the aggregate
  5098 ** function.
  5099 **
  5100 ** This routine must be called from the same thread in which
  5101 ** the aggregate SQL function is running.
  5102 */
  5103 SQLITE_API void *sqlite3_aggregate_context(sqlite3_context*, int nBytes);
  5104 
  5105 /*
  5106 ** CAPI3REF: User Data For Functions
  5107 ** METHOD: sqlite3_context
  5108 **
  5109 ** ^The sqlite3_user_data() interface returns a copy of
  5110 ** the pointer that was the pUserData parameter (the 5th parameter)
  5111 ** of the [sqlite3_create_function()]
  5112 ** and [sqlite3_create_function16()] routines that originally
  5113 ** registered the application defined function.
  5114 **
  5115 ** This routine must be called from the same thread in which
  5116 ** the application-defined function is running.
  5117 */
  5118 SQLITE_API void *sqlite3_user_data(sqlite3_context*);
  5119 
  5120 /*
  5121 ** CAPI3REF: Database Connection For Functions
  5122 ** METHOD: sqlite3_context
  5123 **
  5124 ** ^The sqlite3_context_db_handle() interface returns a copy of
  5125 ** the pointer to the [database connection] (the 1st parameter)
  5126 ** of the [sqlite3_create_function()]
  5127 ** and [sqlite3_create_function16()] routines that originally
  5128 ** registered the application defined function.
  5129 */
  5130 SQLITE_API sqlite3 *sqlite3_context_db_handle(sqlite3_context*);
  5131 
  5132 /*
  5133 ** CAPI3REF: Function Auxiliary Data
  5134 ** METHOD: sqlite3_context
  5135 **
  5136 ** These functions may be used by (non-aggregate) SQL functions to
  5137 ** associate metadata with argument values. If the same value is passed to
  5138 ** multiple invocations of the same SQL function during query execution, under
  5139 ** some circumstances the associated metadata may be preserved.  An example
  5140 ** of where this might be useful is in a regular-expression matching
  5141 ** function. The compiled version of the regular expression can be stored as
  5142 ** metadata associated with the pattern string.  
  5143 ** Then as long as the pattern string remains the same,
  5144 ** the compiled regular expression can be reused on multiple
  5145 ** invocations of the same function.
  5146 **
  5147 ** ^The sqlite3_get_auxdata(C,N) interface returns a pointer to the metadata
  5148 ** associated by the sqlite3_set_auxdata(C,N,P,X) function with the Nth argument
  5149 ** value to the application-defined function.  ^N is zero for the left-most
  5150 ** function argument.  ^If there is no metadata
  5151 ** associated with the function argument, the sqlite3_get_auxdata(C,N) interface
  5152 ** returns a NULL pointer.
  5153 **
  5154 ** ^The sqlite3_set_auxdata(C,N,P,X) interface saves P as metadata for the N-th
  5155 ** argument of the application-defined function.  ^Subsequent
  5156 ** calls to sqlite3_get_auxdata(C,N) return P from the most recent
  5157 ** sqlite3_set_auxdata(C,N,P,X) call if the metadata is still valid or
  5158 ** NULL if the metadata has been discarded.
  5159 ** ^After each call to sqlite3_set_auxdata(C,N,P,X) where X is not NULL,
  5160 ** SQLite will invoke the destructor function X with parameter P exactly
  5161 ** once, when the metadata is discarded.
  5162 ** SQLite is free to discard the metadata at any time, including: <ul>
  5163 ** <li> ^(when the corresponding function parameter changes)^, or
  5164 ** <li> ^(when [sqlite3_reset()] or [sqlite3_finalize()] is called for the
  5165 **      SQL statement)^, or
  5166 ** <li> ^(when sqlite3_set_auxdata() is invoked again on the same
  5167 **       parameter)^, or
  5168 ** <li> ^(during the original sqlite3_set_auxdata() call when a memory 
  5169 **      allocation error occurs.)^ </ul>
  5170 **
  5171 ** Note the last bullet in particular.  The destructor X in 
  5172 ** sqlite3_set_auxdata(C,N,P,X) might be called immediately, before the
  5173 ** sqlite3_set_auxdata() interface even returns.  Hence sqlite3_set_auxdata()
  5174 ** should be called near the end of the function implementation and the
  5175 ** function implementation should not make any use of P after
  5176 ** sqlite3_set_auxdata() has been called.
  5177 **
  5178 ** ^(In practice, metadata is preserved between function calls for
  5179 ** function parameters that are compile-time constants, including literal
  5180 ** values and [parameters] and expressions composed from the same.)^
  5181 **
  5182 ** The value of the N parameter to these interfaces should be non-negative.
  5183 ** Future enhancements may make use of negative N values to define new
  5184 ** kinds of function caching behavior.
  5185 **
  5186 ** These routines must be called from the same thread in which
  5187 ** the SQL function is running.
  5188 */
  5189 SQLITE_API void *sqlite3_get_auxdata(sqlite3_context*, int N);
  5190 SQLITE_API void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));
  5191 
  5192 
  5193 /*
  5194 ** CAPI3REF: Constants Defining Special Destructor Behavior
  5195 **
  5196 ** These are special values for the destructor that is passed in as the
  5197 ** final argument to routines like [sqlite3_result_blob()].  ^If the destructor
  5198 ** argument is SQLITE_STATIC, it means that the content pointer is constant
  5199 ** and will never change.  It does not need to be destroyed.  ^The
  5200 ** SQLITE_TRANSIENT value means that the content will likely change in
  5201 ** the near future and that SQLite should make its own private copy of
  5202 ** the content before returning.
  5203 **
  5204 ** The typedef is necessary to work around problems in certain
  5205 ** C++ compilers.
  5206 */
  5207 typedef void (*sqlite3_destructor_type)(void*);
  5208 #define SQLITE_STATIC      ((sqlite3_destructor_type)0)
  5209 #define SQLITE_TRANSIENT   ((sqlite3_destructor_type)-1)
  5210 
  5211 /*
  5212 ** CAPI3REF: Setting The Result Of An SQL Function
  5213 ** METHOD: sqlite3_context
  5214 **
  5215 ** These routines are used by the xFunc or xFinal callbacks that
  5216 ** implement SQL functions and aggregates.  See
  5217 ** [sqlite3_create_function()] and [sqlite3_create_function16()]
  5218 ** for additional information.
  5219 **
  5220 ** These functions work very much like the [parameter binding] family of
  5221 ** functions used to bind values to host parameters in prepared statements.
  5222 ** Refer to the [SQL parameter] documentation for additional information.
  5223 **
  5224 ** ^The sqlite3_result_blob() interface sets the result from
  5225 ** an application-defined function to be the BLOB whose content is pointed
  5226 ** to by the second parameter and which is N bytes long where N is the
  5227 ** third parameter.
  5228 **
  5229 ** ^The sqlite3_result_zeroblob(C,N) and sqlite3_result_zeroblob64(C,N)
  5230 ** interfaces set the result of the application-defined function to be
  5231 ** a BLOB containing all zero bytes and N bytes in size.
  5232 **
  5233 ** ^The sqlite3_result_double() interface sets the result from
  5234 ** an application-defined function to be a floating point value specified
  5235 ** by its 2nd argument.
  5236 **
  5237 ** ^The sqlite3_result_error() and sqlite3_result_error16() functions
  5238 ** cause the implemented SQL function to throw an exception.
  5239 ** ^SQLite uses the string pointed to by the
  5240 ** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
  5241 ** as the text of an error message.  ^SQLite interprets the error
  5242 ** message string from sqlite3_result_error() as UTF-8. ^SQLite
  5243 ** interprets the string from sqlite3_result_error16() as UTF-16 in native
  5244 ** byte order.  ^If the third parameter to sqlite3_result_error()
  5245 ** or sqlite3_result_error16() is negative then SQLite takes as the error
  5246 ** message all text up through the first zero character.
  5247 ** ^If the third parameter to sqlite3_result_error() or
  5248 ** sqlite3_result_error16() is non-negative then SQLite takes that many
  5249 ** bytes (not characters) from the 2nd parameter as the error message.
  5250 ** ^The sqlite3_result_error() and sqlite3_result_error16()
  5251 ** routines make a private copy of the error message text before
  5252 ** they return.  Hence, the calling function can deallocate or
  5253 ** modify the text after they return without harm.
  5254 ** ^The sqlite3_result_error_code() function changes the error code
  5255 ** returned by SQLite as a result of an error in a function.  ^By default,
  5256 ** the error code is SQLITE_ERROR.  ^A subsequent call to sqlite3_result_error()
  5257 ** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
  5258 **
  5259 ** ^The sqlite3_result_error_toobig() interface causes SQLite to throw an
  5260 ** error indicating that a string or BLOB is too long to represent.
  5261 **
  5262 ** ^The sqlite3_result_error_nomem() interface causes SQLite to throw an
  5263 ** error indicating that a memory allocation failed.
  5264 **
  5265 ** ^The sqlite3_result_int() interface sets the return value
  5266 ** of the application-defined function to be the 32-bit signed integer
  5267 ** value given in the 2nd argument.
  5268 ** ^The sqlite3_result_int64() interface sets the return value
  5269 ** of the application-defined function to be the 64-bit signed integer
  5270 ** value given in the 2nd argument.
  5271 **
  5272 ** ^The sqlite3_result_null() interface sets the return value
  5273 ** of the application-defined function to be NULL.
  5274 **
  5275 ** ^The sqlite3_result_text(), sqlite3_result_text16(),
  5276 ** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
  5277 ** set the return value of the application-defined function to be
  5278 ** a text string which is represented as UTF-8, UTF-16 native byte order,
  5279 ** UTF-16 little endian, or UTF-16 big endian, respectively.
  5280 ** ^The sqlite3_result_text64() interface sets the return value of an
  5281 ** application-defined function to be a text string in an encoding
  5282 ** specified by the fifth (and last) parameter, which must be one
  5283 ** of [SQLITE_UTF8], [SQLITE_UTF16], [SQLITE_UTF16BE], or [SQLITE_UTF16LE].
  5284 ** ^SQLite takes the text result from the application from
  5285 ** the 2nd parameter of the sqlite3_result_text* interfaces.
  5286 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
  5287 ** is negative, then SQLite takes result text from the 2nd parameter
  5288 ** through the first zero character.
  5289 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
  5290 ** is non-negative, then as many bytes (not characters) of the text
  5291 ** pointed to by the 2nd parameter are taken as the application-defined
  5292 ** function result.  If the 3rd parameter is non-negative, then it
  5293 ** must be the byte offset into the string where the NUL terminator would
  5294 ** appear if the string where NUL terminated.  If any NUL characters occur
  5295 ** in the string at a byte offset that is less than the value of the 3rd
  5296 ** parameter, then the resulting string will contain embedded NULs and the
  5297 ** result of expressions operating on strings with embedded NULs is undefined.
  5298 ** ^If the 4th parameter to the sqlite3_result_text* interfaces
  5299 ** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
  5300 ** function as the destructor on the text or BLOB result when it has
  5301 ** finished using that result.
  5302 ** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
  5303 ** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
  5304 ** assumes that the text or BLOB result is in constant space and does not
  5305 ** copy the content of the parameter nor call a destructor on the content
  5306 ** when it has finished using that result.
  5307 ** ^If the 4th parameter to the sqlite3_result_text* interfaces
  5308 ** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
  5309 ** then SQLite makes a copy of the result into space obtained
  5310 ** from [sqlite3_malloc()] before it returns.
  5311 **
  5312 ** ^The sqlite3_result_value() interface sets the result of
  5313 ** the application-defined function to be a copy of the
  5314 ** [unprotected sqlite3_value] object specified by the 2nd parameter.  ^The
  5315 ** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
  5316 ** so that the [sqlite3_value] specified in the parameter may change or
  5317 ** be deallocated after sqlite3_result_value() returns without harm.
  5318 ** ^A [protected sqlite3_value] object may always be used where an
  5319 ** [unprotected sqlite3_value] object is required, so either
  5320 ** kind of [sqlite3_value] object can be used with this interface.
  5321 **
  5322 ** ^The sqlite3_result_pointer(C,P,T,D) interface sets the result to an
  5323 ** SQL NULL value, just like [sqlite3_result_null(C)], except that it
  5324 ** also associates the host-language pointer P or type T with that 
  5325 ** NULL value such that the pointer can be retrieved within an
  5326 ** [application-defined SQL function] using [sqlite3_value_pointer()].
  5327 ** ^If the D parameter is not NULL, then it is a pointer to a destructor
  5328 ** for the P parameter.  ^SQLite invokes D with P as its only argument
  5329 ** when SQLite is finished with P.  The T parameter should be a static
  5330 ** string and preferably a string literal. The sqlite3_result_pointer()
  5331 ** routine is part of the [pointer passing interface] added for SQLite 3.20.0.
  5332 **
  5333 ** If these routines are called from within the different thread
  5334 ** than the one containing the application-defined function that received
  5335 ** the [sqlite3_context] pointer, the results are undefined.
  5336 */
  5337 SQLITE_API void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
  5338 SQLITE_API void sqlite3_result_blob64(sqlite3_context*,const void*,
  5339                            sqlite3_uint64,void(*)(void*));
  5340 SQLITE_API void sqlite3_result_double(sqlite3_context*, double);
  5341 SQLITE_API void sqlite3_result_error(sqlite3_context*, const char*, int);
  5342 SQLITE_API void sqlite3_result_error16(sqlite3_context*, const void*, int);
  5343 SQLITE_API void sqlite3_result_error_toobig(sqlite3_context*);
  5344 SQLITE_API void sqlite3_result_error_nomem(sqlite3_context*);
  5345 SQLITE_API void sqlite3_result_error_code(sqlite3_context*, int);
  5346 SQLITE_API void sqlite3_result_int(sqlite3_context*, int);
  5347 SQLITE_API void sqlite3_result_int64(sqlite3_context*, sqlite3_int64);
  5348 SQLITE_API void sqlite3_result_null(sqlite3_context*);
  5349 SQLITE_API void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
  5350 SQLITE_API void sqlite3_result_text64(sqlite3_context*, const char*,sqlite3_uint64,
  5351                            void(*)(void*), unsigned char encoding);
  5352 SQLITE_API void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
  5353 SQLITE_API void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
  5354 SQLITE_API void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
  5355 SQLITE_API void sqlite3_result_value(sqlite3_context*, sqlite3_value*);
  5356 SQLITE_API void sqlite3_result_pointer(sqlite3_context*, void*,const char*,void(*)(void*));
  5357 SQLITE_API void sqlite3_result_zeroblob(sqlite3_context*, int n);
  5358 SQLITE_API int sqlite3_result_zeroblob64(sqlite3_context*, sqlite3_uint64 n);
  5359 
  5360 
  5361 /*
  5362 ** CAPI3REF: Setting The Subtype Of An SQL Function
  5363 ** METHOD: sqlite3_context
  5364 **
  5365 ** The sqlite3_result_subtype(C,T) function causes the subtype of
  5366 ** the result from the [application-defined SQL function] with 
  5367 ** [sqlite3_context] C to be the value T.  Only the lower 8 bits 
  5368 ** of the subtype T are preserved in current versions of SQLite;
  5369 ** higher order bits are discarded.
  5370 ** The number of subtype bytes preserved by SQLite might increase
  5371 ** in future releases of SQLite.
  5372 */
  5373 SQLITE_API void sqlite3_result_subtype(sqlite3_context*,unsigned int);
  5374 
  5375 /*
  5376 ** CAPI3REF: Define New Collating Sequences
  5377 ** METHOD: sqlite3
  5378 **
  5379 ** ^These functions add, remove, or modify a [collation] associated
  5380 ** with the [database connection] specified as the first argument.
  5381 **
  5382 ** ^The name of the collation is a UTF-8 string
  5383 ** for sqlite3_create_collation() and sqlite3_create_collation_v2()
  5384 ** and a UTF-16 string in native byte order for sqlite3_create_collation16().
  5385 ** ^Collation names that compare equal according to [sqlite3_strnicmp()] are
  5386 ** considered to be the same name.
  5387 **
  5388 ** ^(The third argument (eTextRep) must be one of the constants:
  5389 ** <ul>
  5390 ** <li> [SQLITE_UTF8],
  5391 ** <li> [SQLITE_UTF16LE],
  5392 ** <li> [SQLITE_UTF16BE],
  5393 ** <li> [SQLITE_UTF16], or
  5394 ** <li> [SQLITE_UTF16_ALIGNED].
  5395 ** </ul>)^
  5396 ** ^The eTextRep argument determines the encoding of strings passed
  5397 ** to the collating function callback, xCallback.
  5398 ** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep
  5399 ** force strings to be UTF16 with native byte order.
  5400 ** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin
  5401 ** on an even byte address.
  5402 **
  5403 ** ^The fourth argument, pArg, is an application data pointer that is passed
  5404 ** through as the first argument to the collating function callback.
  5405 **
  5406 ** ^The fifth argument, xCallback, is a pointer to the collating function.
  5407 ** ^Multiple collating functions can be registered using the same name but
  5408 ** with different eTextRep parameters and SQLite will use whichever
  5409 ** function requires the least amount of data transformation.
  5410 ** ^If the xCallback argument is NULL then the collating function is
  5411 ** deleted.  ^When all collating functions having the same name are deleted,
  5412 ** that collation is no longer usable.
  5413 **
  5414 ** ^The collating function callback is invoked with a copy of the pArg 
  5415 ** application data pointer and with two strings in the encoding specified
  5416 ** by the eTextRep argument.  The collating function must return an
  5417 ** integer that is negative, zero, or positive
  5418 ** if the first string is less than, equal to, or greater than the second,
  5419 ** respectively.  A collating function must always return the same answer
  5420 ** given the same inputs.  If two or more collating functions are registered
  5421 ** to the same collation name (using different eTextRep values) then all
  5422 ** must give an equivalent answer when invoked with equivalent strings.
  5423 ** The collating function must obey the following properties for all
  5424 ** strings A, B, and C:
  5425 **
  5426 ** <ol>
  5427 ** <li> If A==B then B==A.
  5428 ** <li> If A==B and B==C then A==C.
  5429 ** <li> If A&lt;B THEN B&gt;A.
  5430 ** <li> If A&lt;B and B&lt;C then A&lt;C.
  5431 ** </ol>
  5432 **
  5433 ** If a collating function fails any of the above constraints and that
  5434 ** collating function is  registered and used, then the behavior of SQLite
  5435 ** is undefined.
  5436 **
  5437 ** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation()
  5438 ** with the addition that the xDestroy callback is invoked on pArg when
  5439 ** the collating function is deleted.
  5440 ** ^Collating functions are deleted when they are overridden by later
  5441 ** calls to the collation creation functions or when the
  5442 ** [database connection] is closed using [sqlite3_close()].
  5443 **
  5444 ** ^The xDestroy callback is <u>not</u> called if the 
  5445 ** sqlite3_create_collation_v2() function fails.  Applications that invoke
  5446 ** sqlite3_create_collation_v2() with a non-NULL xDestroy argument should 
  5447 ** check the return code and dispose of the application data pointer
  5448 ** themselves rather than expecting SQLite to deal with it for them.
  5449 ** This is different from every other SQLite interface.  The inconsistency 
  5450 ** is unfortunate but cannot be changed without breaking backwards 
  5451 ** compatibility.
  5452 **
  5453 ** See also:  [sqlite3_collation_needed()] and [sqlite3_collation_needed16()].
  5454 */
  5455 SQLITE_API int sqlite3_create_collation(
  5456   sqlite3*, 
  5457   const char *zName, 
  5458   int eTextRep, 
  5459   void *pArg,
  5460   int(*xCompare)(void*,int,const void*,int,const void*)
  5461 );
  5462 SQLITE_API int sqlite3_create_collation_v2(
  5463   sqlite3*, 
  5464   const char *zName, 
  5465   int eTextRep, 
  5466   void *pArg,
  5467   int(*xCompare)(void*,int,const void*,int,const void*),
  5468   void(*xDestroy)(void*)
  5469 );
  5470 SQLITE_API int sqlite3_create_collation16(
  5471   sqlite3*, 
  5472   const void *zName,
  5473   int eTextRep, 
  5474   void *pArg,
  5475   int(*xCompare)(void*,int,const void*,int,const void*)
  5476 );
  5477 
  5478 /*
  5479 ** CAPI3REF: Collation Needed Callbacks
  5480 ** METHOD: sqlite3
  5481 **
  5482 ** ^To avoid having to register all collation sequences before a database
  5483 ** can be used, a single callback function may be registered with the
  5484 ** [database connection] to be invoked whenever an undefined collation
  5485 ** sequence is required.
  5486 **
  5487 ** ^If the function is registered using the sqlite3_collation_needed() API,
  5488 ** then it is passed the names of undefined collation sequences as strings
  5489 ** encoded in UTF-8. ^If sqlite3_collation_needed16() is used,
  5490 ** the names are passed as UTF-16 in machine native byte order.
  5491 ** ^A call to either function replaces the existing collation-needed callback.
  5492 **
  5493 ** ^(When the callback is invoked, the first argument passed is a copy
  5494 ** of the second argument to sqlite3_collation_needed() or
  5495 ** sqlite3_collation_needed16().  The second argument is the database
  5496 ** connection.  The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
  5497 ** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
  5498 ** sequence function required.  The fourth parameter is the name of the
  5499 ** required collation sequence.)^
  5500 **
  5501 ** The callback function should register the desired collation using
  5502 ** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
  5503 ** [sqlite3_create_collation_v2()].
  5504 */
  5505 SQLITE_API int sqlite3_collation_needed(
  5506   sqlite3*, 
  5507   void*, 
  5508   void(*)(void*,sqlite3*,int eTextRep,const char*)
  5509 );
  5510 SQLITE_API int sqlite3_collation_needed16(
  5511   sqlite3*, 
  5512   void*,
  5513   void(*)(void*,sqlite3*,int eTextRep,const void*)
  5514 );
  5515 
  5516 #ifdef SQLITE_HAS_CODEC
  5517 /*
  5518 ** Specify the key for an encrypted database.  This routine should be
  5519 ** called right after sqlite3_open().
  5520 **
  5521 ** The code to implement this API is not available in the public release
  5522 ** of SQLite.
  5523 */
  5524 SQLITE_API int sqlite3_key(
  5525   sqlite3 *db,                   /* Database to be rekeyed */
  5526   const void *pKey, int nKey     /* The key */
  5527 );
  5528 SQLITE_API int sqlite3_key_v2(
  5529   sqlite3 *db,                   /* Database to be rekeyed */
  5530   const char *zDbName,           /* Name of the database */
  5531   const void *pKey, int nKey     /* The key */
  5532 );
  5533 
  5534 /*
  5535 ** Change the key on an open database.  If the current database is not
  5536 ** encrypted, this routine will encrypt it.  If pNew==0 or nNew==0, the
  5537 ** database is decrypted.
  5538 **
  5539 ** The code to implement this API is not available in the public release
  5540 ** of SQLite.
  5541 */
  5542 SQLITE_API int sqlite3_rekey(
  5543   sqlite3 *db,                   /* Database to be rekeyed */
  5544   const void *pKey, int nKey     /* The new key */
  5545 );
  5546 SQLITE_API int sqlite3_rekey_v2(
  5547   sqlite3 *db,                   /* Database to be rekeyed */
  5548   const char *zDbName,           /* Name of the database */
  5549   const void *pKey, int nKey     /* The new key */
  5550 );
  5551 
  5552 /*
  5553 ** Specify the activation key for a SEE database.  Unless 
  5554 ** activated, none of the SEE routines will work.
  5555 */
  5556 SQLITE_API void sqlite3_activate_see(
  5557   const char *zPassPhrase        /* Activation phrase */
  5558 );
  5559 #endif
  5560 
  5561 #ifdef SQLITE_ENABLE_CEROD
  5562 /*
  5563 ** Specify the activation key for a CEROD database.  Unless 
  5564 ** activated, none of the CEROD routines will work.
  5565 */
  5566 SQLITE_API void sqlite3_activate_cerod(
  5567   const char *zPassPhrase        /* Activation phrase */
  5568 );
  5569 #endif
  5570 
  5571 /*
  5572 ** CAPI3REF: Suspend Execution For A Short Time
  5573 **
  5574 ** The sqlite3_sleep() function causes the current thread to suspend execution
  5575 ** for at least a number of milliseconds specified in its parameter.
  5576 **
  5577 ** If the operating system does not support sleep requests with
  5578 ** millisecond time resolution, then the time will be rounded up to
  5579 ** the nearest second. The number of milliseconds of sleep actually
  5580 ** requested from the operating system is returned.
  5581 **
  5582 ** ^SQLite implements this interface by calling the xSleep()
  5583 ** method of the default [sqlite3_vfs] object.  If the xSleep() method
  5584 ** of the default VFS is not implemented correctly, or not implemented at
  5585 ** all, then the behavior of sqlite3_sleep() may deviate from the description
  5586 ** in the previous paragraphs.
  5587 */
  5588 SQLITE_API int sqlite3_sleep(int);
  5589 
  5590 /*
  5591 ** CAPI3REF: Name Of The Folder Holding Temporary Files
  5592 **
  5593 ** ^(If this global variable is made to point to a string which is
  5594 ** the name of a folder (a.k.a. directory), then all temporary files
  5595 ** created by SQLite when using a built-in [sqlite3_vfs | VFS]
  5596 ** will be placed in that directory.)^  ^If this variable
  5597 ** is a NULL pointer, then SQLite performs a search for an appropriate
  5598 ** temporary file directory.
  5599 **
  5600 ** Applications are strongly discouraged from using this global variable.
  5601 ** It is required to set a temporary folder on Windows Runtime (WinRT).
  5602 ** But for all other platforms, it is highly recommended that applications
  5603 ** neither read nor write this variable.  This global variable is a relic
  5604 ** that exists for backwards compatibility of legacy applications and should
  5605 ** be avoided in new projects.
  5606 **
  5607 ** It is not safe to read or modify this variable in more than one
  5608 ** thread at a time.  It is not safe to read or modify this variable
  5609 ** if a [database connection] is being used at the same time in a separate
  5610 ** thread.
  5611 ** It is intended that this variable be set once
  5612 ** as part of process initialization and before any SQLite interface
  5613 ** routines have been called and that this variable remain unchanged
  5614 ** thereafter.
  5615 **
  5616 ** ^The [temp_store_directory pragma] may modify this variable and cause
  5617 ** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
  5618 ** the [temp_store_directory pragma] always assumes that any string
  5619 ** that this variable points to is held in memory obtained from 
  5620 ** [sqlite3_malloc] and the pragma may attempt to free that memory
  5621 ** using [sqlite3_free].
  5622 ** Hence, if this variable is modified directly, either it should be
  5623 ** made NULL or made to point to memory obtained from [sqlite3_malloc]
  5624 ** or else the use of the [temp_store_directory pragma] should be avoided.
  5625 ** Except when requested by the [temp_store_directory pragma], SQLite
  5626 ** does not free the memory that sqlite3_temp_directory points to.  If
  5627 ** the application wants that memory to be freed, it must do
  5628 ** so itself, taking care to only do so after all [database connection]
  5629 ** objects have been destroyed.
  5630 **
  5631 ** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
  5632 ** prior to calling [sqlite3_open] or [sqlite3_open_v2].  Otherwise, various
  5633 ** features that require the use of temporary files may fail.  Here is an
  5634 ** example of how to do this using C++ with the Windows Runtime:
  5635 **
  5636 ** <blockquote><pre>
  5637 ** LPCWSTR zPath = Windows::Storage::ApplicationData::Current->
  5638 ** &nbsp;     TemporaryFolder->Path->Data();
  5639 ** char zPathBuf&#91;MAX_PATH + 1&#93;;
  5640 ** memset(zPathBuf, 0, sizeof(zPathBuf));
  5641 ** WideCharToMultiByte(CP_UTF8, 0, zPath, -1, zPathBuf, sizeof(zPathBuf),
  5642 ** &nbsp;     NULL, NULL);
  5643 ** sqlite3_temp_directory = sqlite3_mprintf("%s", zPathBuf);
  5644 ** </pre></blockquote>
  5645 */
  5646 SQLITE_API SQLITE_EXTERN char *sqlite3_temp_directory;
  5647 
  5648 /*
  5649 ** CAPI3REF: Name Of The Folder Holding Database Files
  5650 **
  5651 ** ^(If this global variable is made to point to a string which is
  5652 ** the name of a folder (a.k.a. directory), then all database files
  5653 ** specified with a relative pathname and created or accessed by
  5654 ** SQLite when using a built-in windows [sqlite3_vfs | VFS] will be assumed
  5655 ** to be relative to that directory.)^ ^If this variable is a NULL
  5656 ** pointer, then SQLite assumes that all database files specified
  5657 ** with a relative pathname are relative to the current directory
  5658 ** for the process.  Only the windows VFS makes use of this global
  5659 ** variable; it is ignored by the unix VFS.
  5660 **
  5661 ** Changing the value of this variable while a database connection is
  5662 ** open can result in a corrupt database.
  5663 **
  5664 ** It is not safe to read or modify this variable in more than one
  5665 ** thread at a time.  It is not safe to read or modify this variable
  5666 ** if a [database connection] is being used at the same time in a separate
  5667 ** thread.
  5668 ** It is intended that this variable be set once
  5669 ** as part of process initialization and before any SQLite interface
  5670 ** routines have been called and that this variable remain unchanged
  5671 ** thereafter.
  5672 **
  5673 ** ^The [data_store_directory pragma] may modify this variable and cause
  5674 ** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
  5675 ** the [data_store_directory pragma] always assumes that any string
  5676 ** that this variable points to is held in memory obtained from 
  5677 ** [sqlite3_malloc] and the pragma may attempt to free that memory
  5678 ** using [sqlite3_free].
  5679 ** Hence, if this variable is modified directly, either it should be
  5680 ** made NULL or made to point to memory obtained from [sqlite3_malloc]
  5681 ** or else the use of the [data_store_directory pragma] should be avoided.
  5682 */
  5683 SQLITE_API SQLITE_EXTERN char *sqlite3_data_directory;
  5684 
  5685 /*
  5686 ** CAPI3REF: Win32 Specific Interface
  5687 **
  5688 ** These interfaces are available only on Windows.  The
  5689 ** [sqlite3_win32_set_directory] interface is used to set the value associated
  5690 ** with the [sqlite3_temp_directory] or [sqlite3_data_directory] variable, to
  5691 ** zValue, depending on the value of the type parameter.  The zValue parameter
  5692 ** should be NULL to cause the previous value to be freed via [sqlite3_free];
  5693 ** a non-NULL value will be copied into memory obtained from [sqlite3_malloc]
  5694 ** prior to being used.  The [sqlite3_win32_set_directory] interface returns
  5695 ** [SQLITE_OK] to indicate success, [SQLITE_ERROR] if the type is unsupported,
  5696 ** or [SQLITE_NOMEM] if memory could not be allocated.  The value of the
  5697 ** [sqlite3_data_directory] variable is intended to act as a replacement for
  5698 ** the current directory on the sub-platforms of Win32 where that concept is
  5699 ** not present, e.g. WinRT and UWP.  The [sqlite3_win32_set_directory8] and
  5700 ** [sqlite3_win32_set_directory16] interfaces behave exactly the same as the
  5701 ** sqlite3_win32_set_directory interface except the string parameter must be
  5702 ** UTF-8 or UTF-16, respectively.
  5703 */
  5704 SQLITE_API int sqlite3_win32_set_directory(
  5705   unsigned long type, /* Identifier for directory being set or reset */
  5706   void *zValue        /* New value for directory being set or reset */
  5707 );
  5708 SQLITE_API int sqlite3_win32_set_directory8(unsigned long type, const char *zValue);
  5709 SQLITE_API int sqlite3_win32_set_directory16(unsigned long type, const void *zValue);
  5710 
  5711 /*
  5712 ** CAPI3REF: Win32 Directory Types
  5713 **
  5714 ** These macros are only available on Windows.  They define the allowed values
  5715 ** for the type argument to the [sqlite3_win32_set_directory] interface.
  5716 */
  5717 #define SQLITE_WIN32_DATA_DIRECTORY_TYPE  1
  5718 #define SQLITE_WIN32_TEMP_DIRECTORY_TYPE  2
  5719 
  5720 /*
  5721 ** CAPI3REF: Test For Auto-Commit Mode
  5722 ** KEYWORDS: {autocommit mode}
  5723 ** METHOD: sqlite3
  5724 **
  5725 ** ^The sqlite3_get_autocommit() interface returns non-zero or
  5726 ** zero if the given database connection is or is not in autocommit mode,
  5727 ** respectively.  ^Autocommit mode is on by default.
  5728 ** ^Autocommit mode is disabled by a [BEGIN] statement.
  5729 ** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
  5730 **
  5731 ** If certain kinds of errors occur on a statement within a multi-statement
  5732 ** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
  5733 ** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the
  5734 ** transaction might be rolled back automatically.  The only way to
  5735 ** find out whether SQLite automatically rolled back the transaction after
  5736 ** an error is to use this function.
  5737 **
  5738 ** If another thread changes the autocommit status of the database
  5739 ** connection while this routine is running, then the return value
  5740 ** is undefined.
  5741 */
  5742 SQLITE_API int sqlite3_get_autocommit(sqlite3*);
  5743 
  5744 /*
  5745 ** CAPI3REF: Find The Database Handle Of A Prepared Statement
  5746 ** METHOD: sqlite3_stmt
  5747 **
  5748 ** ^The sqlite3_db_handle interface returns the [database connection] handle
  5749 ** to which a [prepared statement] belongs.  ^The [database connection]
  5750 ** returned by sqlite3_db_handle is the same [database connection]
  5751 ** that was the first argument
  5752 ** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
  5753 ** create the statement in the first place.
  5754 */
  5755 SQLITE_API sqlite3 *sqlite3_db_handle(sqlite3_stmt*);
  5756 
  5757 /*
  5758 ** CAPI3REF: Return The Filename For A Database Connection
  5759 ** METHOD: sqlite3
  5760 **
  5761 ** ^The sqlite3_db_filename(D,N) interface returns a pointer to a filename
  5762 ** associated with database N of connection D.  ^The main database file
  5763 ** has the name "main".  If there is no attached database N on the database
  5764 ** connection D, or if database N is a temporary or in-memory database, then
  5765 ** a NULL pointer is returned.
  5766 **
  5767 ** ^The filename returned by this function is the output of the
  5768 ** xFullPathname method of the [VFS].  ^In other words, the filename
  5769 ** will be an absolute pathname, even if the filename used
  5770 ** to open the database originally was a URI or relative pathname.
  5771 */
  5772 SQLITE_API const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName);
  5773 
  5774 /*
  5775 ** CAPI3REF: Determine if a database is read-only
  5776 ** METHOD: sqlite3
  5777 **
  5778 ** ^The sqlite3_db_readonly(D,N) interface returns 1 if the database N
  5779 ** of connection D is read-only, 0 if it is read/write, or -1 if N is not
  5780 ** the name of a database on connection D.
  5781 */
  5782 SQLITE_API int sqlite3_db_readonly(sqlite3 *db, const char *zDbName);
  5783 
  5784 /*
  5785 ** CAPI3REF: Find the next prepared statement
  5786 ** METHOD: sqlite3
  5787 **
  5788 ** ^This interface returns a pointer to the next [prepared statement] after
  5789 ** pStmt associated with the [database connection] pDb.  ^If pStmt is NULL
  5790 ** then this interface returns a pointer to the first prepared statement
  5791 ** associated with the database connection pDb.  ^If no prepared statement
  5792 ** satisfies the conditions of this routine, it returns NULL.
  5793 **
  5794 ** The [database connection] pointer D in a call to
  5795 ** [sqlite3_next_stmt(D,S)] must refer to an open database
  5796 ** connection and in particular must not be a NULL pointer.
  5797 */
  5798 SQLITE_API sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);
  5799 
  5800 /*
  5801 ** CAPI3REF: Commit And Rollback Notification Callbacks
  5802 ** METHOD: sqlite3
  5803 **
  5804 ** ^The sqlite3_commit_hook() interface registers a callback
  5805 ** function to be invoked whenever a transaction is [COMMIT | committed].
  5806 ** ^Any callback set by a previous call to sqlite3_commit_hook()
  5807 ** for the same database connection is overridden.
  5808 ** ^The sqlite3_rollback_hook() interface registers a callback
  5809 ** function to be invoked whenever a transaction is [ROLLBACK | rolled back].
  5810 ** ^Any callback set by a previous call to sqlite3_rollback_hook()
  5811 ** for the same database connection is overridden.
  5812 ** ^The pArg argument is passed through to the callback.
  5813 ** ^If the callback on a commit hook function returns non-zero,
  5814 ** then the commit is converted into a rollback.
  5815 **
  5816 ** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions
  5817 ** return the P argument from the previous call of the same function
  5818 ** on the same [database connection] D, or NULL for
  5819 ** the first call for each function on D.
  5820 **
  5821 ** The commit and rollback hook callbacks are not reentrant.
  5822 ** The callback implementation must not do anything that will modify
  5823 ** the database connection that invoked the callback.  Any actions
  5824 ** to modify the database connection must be deferred until after the
  5825 ** completion of the [sqlite3_step()] call that triggered the commit
  5826 ** or rollback hook in the first place.
  5827 ** Note that running any other SQL statements, including SELECT statements,
  5828 ** or merely calling [sqlite3_prepare_v2()] and [sqlite3_step()] will modify
  5829 ** the database connections for the meaning of "modify" in this paragraph.
  5830 **
  5831 ** ^Registering a NULL function disables the callback.
  5832 **
  5833 ** ^When the commit hook callback routine returns zero, the [COMMIT]
  5834 ** operation is allowed to continue normally.  ^If the commit hook
  5835 ** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].
  5836 ** ^The rollback hook is invoked on a rollback that results from a commit
  5837 ** hook returning non-zero, just as it would be with any other rollback.
  5838 **
  5839 ** ^For the purposes of this API, a transaction is said to have been
  5840 ** rolled back if an explicit "ROLLBACK" statement is executed, or
  5841 ** an error or constraint causes an implicit rollback to occur.
  5842 ** ^The rollback callback is not invoked if a transaction is
  5843 ** automatically rolled back because the database connection is closed.
  5844 **
  5845 ** See also the [sqlite3_update_hook()] interface.
  5846 */
  5847 SQLITE_API void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
  5848 SQLITE_API void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
  5849 
  5850 /*
  5851 ** CAPI3REF: Data Change Notification Callbacks
  5852 ** METHOD: sqlite3
  5853 **
  5854 ** ^The sqlite3_update_hook() interface registers a callback function
  5855 ** with the [database connection] identified by the first argument
  5856 ** to be invoked whenever a row is updated, inserted or deleted in
  5857 ** a [rowid table].
  5858 ** ^Any callback set by a previous call to this function
  5859 ** for the same database connection is overridden.
  5860 **
  5861 ** ^The second argument is a pointer to the function to invoke when a
  5862 ** row is updated, inserted or deleted in a rowid table.
  5863 ** ^The first argument to the callback is a copy of the third argument
  5864 ** to sqlite3_update_hook().
  5865 ** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
  5866 ** or [SQLITE_UPDATE], depending on the operation that caused the callback
  5867 ** to be invoked.
  5868 ** ^The third and fourth arguments to the callback contain pointers to the
  5869 ** database and table name containing the affected row.
  5870 ** ^The final callback parameter is the [rowid] of the row.
  5871 ** ^In the case of an update, this is the [rowid] after the update takes place.
  5872 **
  5873 ** ^(The update hook is not invoked when internal system tables are
  5874 ** modified (i.e. sqlite_master and sqlite_sequence).)^
  5875 ** ^The update hook is not invoked when [WITHOUT ROWID] tables are modified.
  5876 **
  5877 ** ^In the current implementation, the update hook
  5878 ** is not invoked when conflicting rows are deleted because of an
  5879 ** [ON CONFLICT | ON CONFLICT REPLACE] clause.  ^Nor is the update hook
  5880 ** invoked when rows are deleted using the [truncate optimization].
  5881 ** The exceptions defined in this paragraph might change in a future
  5882 ** release of SQLite.
  5883 **
  5884 ** The update hook implementation must not do anything that will modify
  5885 ** the database connection that invoked the update hook.  Any actions
  5886 ** to modify the database connection must be deferred until after the
  5887 ** completion of the [sqlite3_step()] call that triggered the update hook.
  5888 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  5889 ** database connections for the meaning of "modify" in this paragraph.
  5890 **
  5891 ** ^The sqlite3_update_hook(D,C,P) function
  5892 ** returns the P argument from the previous call
  5893 ** on the same [database connection] D, or NULL for
  5894 ** the first call on D.
  5895 **
  5896 ** See also the [sqlite3_commit_hook()], [sqlite3_rollback_hook()],
  5897 ** and [sqlite3_preupdate_hook()] interfaces.
  5898 */
  5899 SQLITE_API void *sqlite3_update_hook(
  5900   sqlite3*, 
  5901   void(*)(void *,int ,char const *,char const *,sqlite3_int64),
  5902   void*
  5903 );
  5904 
  5905 /*
  5906 ** CAPI3REF: Enable Or Disable Shared Pager Cache
  5907 **
  5908 ** ^(This routine enables or disables the sharing of the database cache
  5909 ** and schema data structures between [database connection | connections]
  5910 ** to the same database. Sharing is enabled if the argument is true
  5911 ** and disabled if the argument is false.)^
  5912 **
  5913 ** ^Cache sharing is enabled and disabled for an entire process.
  5914 ** This is a change as of SQLite [version 3.5.0] ([dateof:3.5.0]). 
  5915 ** In prior versions of SQLite,
  5916 ** sharing was enabled or disabled for each thread separately.
  5917 **
  5918 ** ^(The cache sharing mode set by this interface effects all subsequent
  5919 ** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
  5920 ** Existing database connections continue use the sharing mode
  5921 ** that was in effect at the time they were opened.)^
  5922 **
  5923 ** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
  5924 ** successfully.  An [error code] is returned otherwise.)^
  5925 **
  5926 ** ^Shared cache is disabled by default. But this might change in
  5927 ** future releases of SQLite.  Applications that care about shared
  5928 ** cache setting should set it explicitly.
  5929 **
  5930 ** Note: This method is disabled on MacOS X 10.7 and iOS version 5.0
  5931 ** and will always return SQLITE_MISUSE. On those systems, 
  5932 ** shared cache mode should be enabled per-database connection via 
  5933 ** [sqlite3_open_v2()] with [SQLITE_OPEN_SHAREDCACHE].
  5934 **
  5935 ** This interface is threadsafe on processors where writing a
  5936 ** 32-bit integer is atomic.
  5937 **
  5938 ** See Also:  [SQLite Shared-Cache Mode]
  5939 */
  5940 SQLITE_API int sqlite3_enable_shared_cache(int);
  5941 
  5942 /*
  5943 ** CAPI3REF: Attempt To Free Heap Memory
  5944 **
  5945 ** ^The sqlite3_release_memory() interface attempts to free N bytes
  5946 ** of heap memory by deallocating non-essential memory allocations
  5947 ** held by the database library.   Memory used to cache database
  5948 ** pages to improve performance is an example of non-essential memory.
  5949 ** ^sqlite3_release_memory() returns the number of bytes actually freed,
  5950 ** which might be more or less than the amount requested.
  5951 ** ^The sqlite3_release_memory() routine is a no-op returning zero
  5952 ** if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT].
  5953 **
  5954 ** See also: [sqlite3_db_release_memory()]
  5955 */
  5956 SQLITE_API int sqlite3_release_memory(int);
  5957 
  5958 /*
  5959 ** CAPI3REF: Free Memory Used By A Database Connection
  5960 ** METHOD: sqlite3
  5961 **
  5962 ** ^The sqlite3_db_release_memory(D) interface attempts to free as much heap
  5963 ** memory as possible from database connection D. Unlike the
  5964 ** [sqlite3_release_memory()] interface, this interface is in effect even
  5965 ** when the [SQLITE_ENABLE_MEMORY_MANAGEMENT] compile-time option is
  5966 ** omitted.
  5967 **
  5968 ** See also: [sqlite3_release_memory()]
  5969 */
  5970 SQLITE_API int sqlite3_db_release_memory(sqlite3*);
  5971 
  5972 /*
  5973 ** CAPI3REF: Impose A Limit On Heap Size
  5974 **
  5975 ** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the
  5976 ** soft limit on the amount of heap memory that may be allocated by SQLite.
  5977 ** ^SQLite strives to keep heap memory utilization below the soft heap
  5978 ** limit by reducing the number of pages held in the page cache
  5979 ** as heap memory usages approaches the limit.
  5980 ** ^The soft heap limit is "soft" because even though SQLite strives to stay
  5981 ** below the limit, it will exceed the limit rather than generate
  5982 ** an [SQLITE_NOMEM]