src/sqlite3.h
author Volker Birk <vb@pep.foundation>
Wed, 29 Aug 2018 17:10:23 +0200
branchsync
changeset 2899 63b619aef131
parent 1912 b2f4e198adef
child 3192 8797e99f7ab2
permissions -rw-r--r--
somewhat bigger
     1 /*
     2 ** 2001 September 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.
   119 **
   120 ** See also: [sqlite3_libversion()],
   121 ** [sqlite3_libversion_number()], [sqlite3_sourceid()],
   122 ** [sqlite_version()] and [sqlite_source_id()].
   123 */
   124 #define SQLITE_VERSION        "3.19.3"
   125 #define SQLITE_VERSION_NUMBER 3019003
   126 #define SQLITE_SOURCE_ID      "2017-06-08 14:26:16 0ee482a1e0eae22e08edc8978c9733a96603d4509645f348ebf55b579e89636b"
   127 
   128 /*
   129 ** CAPI3REF: Run-Time Library Version Numbers
   130 ** KEYWORDS: sqlite3_version sqlite3_sourceid
   131 **
   132 ** These interfaces provide the same information as the [SQLITE_VERSION],
   133 ** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
   134 ** but are associated with the library instead of the header file.  ^(Cautious
   135 ** programmers might include assert() statements in their application to
   136 ** verify that values returned by these interfaces match the macros in
   137 ** the header, and thus ensure that the application is
   138 ** compiled with matching library and header files.
   139 **
   140 ** <blockquote><pre>
   141 ** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
   142 ** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );
   143 ** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
   144 ** </pre></blockquote>)^
   145 **
   146 ** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
   147 ** macro.  ^The sqlite3_libversion() function returns a pointer to the
   148 ** to the sqlite3_version[] string constant.  The sqlite3_libversion()
   149 ** function is provided for use in DLLs since DLL users usually do not have
   150 ** direct access to string constants within the DLL.  ^The
   151 ** sqlite3_libversion_number() function returns an integer equal to
   152 ** [SQLITE_VERSION_NUMBER].  ^The sqlite3_sourceid() function returns 
   153 ** a pointer to a string constant whose value is the same as the 
   154 ** [SQLITE_SOURCE_ID] C preprocessor macro.
   155 **
   156 ** See also: [sqlite_version()] and [sqlite_source_id()].
   157 */
   158 SQLITE_API SQLITE_EXTERN const char sqlite3_version[];
   159 SQLITE_API const char *sqlite3_libversion(void);
   160 SQLITE_API const char *sqlite3_sourceid(void);
   161 SQLITE_API int sqlite3_libversion_number(void);
   162 
   163 /*
   164 ** CAPI3REF: Run-Time Library Compilation Options Diagnostics
   165 **
   166 ** ^The sqlite3_compileoption_used() function returns 0 or 1 
   167 ** indicating whether the specified option was defined at 
   168 ** compile time.  ^The SQLITE_ prefix may be omitted from the 
   169 ** option name passed to sqlite3_compileoption_used().  
   170 **
   171 ** ^The sqlite3_compileoption_get() function allows iterating
   172 ** over the list of options that were defined at compile time by
   173 ** returning the N-th compile time option string.  ^If N is out of range,
   174 ** sqlite3_compileoption_get() returns a NULL pointer.  ^The SQLITE_ 
   175 ** prefix is omitted from any strings returned by 
   176 ** sqlite3_compileoption_get().
   177 **
   178 ** ^Support for the diagnostic functions sqlite3_compileoption_used()
   179 ** and sqlite3_compileoption_get() may be omitted by specifying the 
   180 ** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
   181 **
   182 ** See also: SQL functions [sqlite_compileoption_used()] and
   183 ** [sqlite_compileoption_get()] and the [compile_options pragma].
   184 */
   185 #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
   186 SQLITE_API int sqlite3_compileoption_used(const char *zOptName);
   187 SQLITE_API const char *sqlite3_compileoption_get(int N);
   188 #endif
   189 
   190 /*
   191 ** CAPI3REF: Test To See If The Library Is Threadsafe
   192 **
   193 ** ^The sqlite3_threadsafe() function returns zero if and only if
   194 ** SQLite was compiled with mutexing code omitted due to the
   195 ** [SQLITE_THREADSAFE] compile-time option being set to 0.
   196 **
   197 ** SQLite can be compiled with or without mutexes.  When
   198 ** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes
   199 ** are enabled and SQLite is threadsafe.  When the
   200 ** [SQLITE_THREADSAFE] macro is 0, 
   201 ** the mutexes are omitted.  Without the mutexes, it is not safe
   202 ** to use SQLite concurrently from more than one thread.
   203 **
   204 ** Enabling mutexes incurs a measurable performance penalty.
   205 ** So if speed is of utmost importance, it makes sense to disable
   206 ** the mutexes.  But for maximum safety, mutexes should be enabled.
   207 ** ^The default behavior is for mutexes to be enabled.
   208 **
   209 ** This interface can be used by an application to make sure that the
   210 ** version of SQLite that it is linking against was compiled with
   211 ** the desired setting of the [SQLITE_THREADSAFE] macro.
   212 **
   213 ** This interface only reports on the compile-time mutex setting
   214 ** of the [SQLITE_THREADSAFE] flag.  If SQLite is compiled with
   215 ** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but
   216 ** can be fully or partially disabled using a call to [sqlite3_config()]
   217 ** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],
   218 ** or [SQLITE_CONFIG_SERIALIZED].  ^(The return value of the
   219 ** sqlite3_threadsafe() function shows only the compile-time setting of
   220 ** thread safety, not any run-time changes to that setting made by
   221 ** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()
   222 ** is unchanged by calls to sqlite3_config().)^
   223 **
   224 ** See the [threading mode] documentation for additional information.
   225 */
   226 SQLITE_API int sqlite3_threadsafe(void);
   227 
   228 /*
   229 ** CAPI3REF: Database Connection Handle
   230 ** KEYWORDS: {database connection} {database connections}
   231 **
   232 ** Each open SQLite database is represented by a pointer to an instance of
   233 ** the opaque structure named "sqlite3".  It is useful to think of an sqlite3
   234 ** pointer as an object.  The [sqlite3_open()], [sqlite3_open16()], and
   235 ** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
   236 ** and [sqlite3_close_v2()] are its destructors.  There are many other
   237 ** interfaces (such as
   238 ** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
   239 ** [sqlite3_busy_timeout()] to name but three) that are methods on an
   240 ** sqlite3 object.
   241 */
   242 typedef struct sqlite3 sqlite3;
   243 
   244 /*
   245 ** CAPI3REF: 64-Bit Integer Types
   246 ** KEYWORDS: sqlite_int64 sqlite_uint64
   247 **
   248 ** Because there is no cross-platform way to specify 64-bit integer types
   249 ** SQLite includes typedefs for 64-bit signed and unsigned integers.
   250 **
   251 ** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
   252 ** The sqlite_int64 and sqlite_uint64 types are supported for backwards
   253 ** compatibility only.
   254 **
   255 ** ^The sqlite3_int64 and sqlite_int64 types can store integer values
   256 ** between -9223372036854775808 and +9223372036854775807 inclusive.  ^The
   257 ** sqlite3_uint64 and sqlite_uint64 types can store integer values 
   258 ** between 0 and +18446744073709551615 inclusive.
   259 */
   260 #ifdef SQLITE_INT64_TYPE
   261   typedef SQLITE_INT64_TYPE sqlite_int64;
   262 # ifdef SQLITE_UINT64_TYPE
   263     typedef SQLITE_UINT64_TYPE sqlite_uint64;
   264 # else  
   265     typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
   266 # endif
   267 #elif defined(_MSC_VER) || defined(__BORLANDC__)
   268   typedef __int64 sqlite_int64;
   269   typedef unsigned __int64 sqlite_uint64;
   270 #else
   271   typedef long long int sqlite_int64;
   272   typedef unsigned long long int sqlite_uint64;
   273 #endif
   274 typedef sqlite_int64 sqlite3_int64;
   275 typedef sqlite_uint64 sqlite3_uint64;
   276 
   277 /*
   278 ** If compiling for a processor that lacks floating point support,
   279 ** substitute integer for floating-point.
   280 */
   281 #ifdef SQLITE_OMIT_FLOATING_POINT
   282 # define double sqlite3_int64
   283 #endif
   284 
   285 /*
   286 ** CAPI3REF: Closing A Database Connection
   287 ** DESTRUCTOR: sqlite3
   288 **
   289 ** ^The sqlite3_close() and sqlite3_close_v2() routines are destructors
   290 ** for the [sqlite3] object.
   291 ** ^Calls to sqlite3_close() and sqlite3_close_v2() return [SQLITE_OK] if
   292 ** the [sqlite3] object is successfully destroyed and all associated
   293 ** resources are deallocated.
   294 **
   295 ** ^If the database connection is associated with unfinalized prepared
   296 ** statements or unfinished sqlite3_backup objects then sqlite3_close()
   297 ** will leave the database connection open and return [SQLITE_BUSY].
   298 ** ^If sqlite3_close_v2() is called with unfinalized prepared statements
   299 ** and/or unfinished sqlite3_backups, then the database connection becomes
   300 ** an unusable "zombie" which will automatically be deallocated when the
   301 ** last prepared statement is finalized or the last sqlite3_backup is
   302 ** finished.  The sqlite3_close_v2() interface is intended for use with
   303 ** host languages that are garbage collected, and where the order in which
   304 ** destructors are called is arbitrary.
   305 **
   306 ** Applications should [sqlite3_finalize | finalize] all [prepared statements],
   307 ** [sqlite3_blob_close | close] all [BLOB handles], and 
   308 ** [sqlite3_backup_finish | finish] all [sqlite3_backup] objects associated
   309 ** with the [sqlite3] object prior to attempting to close the object.  ^If
   310 ** sqlite3_close_v2() is called on a [database connection] that still has
   311 ** outstanding [prepared statements], [BLOB handles], and/or
   312 ** [sqlite3_backup] objects then it returns [SQLITE_OK] and the deallocation
   313 ** of resources is deferred until all [prepared statements], [BLOB handles],
   314 ** and [sqlite3_backup] objects are also destroyed.
   315 **
   316 ** ^If an [sqlite3] object is destroyed while a transaction is open,
   317 ** the transaction is automatically rolled back.
   318 **
   319 ** The C parameter to [sqlite3_close(C)] and [sqlite3_close_v2(C)]
   320 ** must be either a NULL
   321 ** pointer or an [sqlite3] object pointer obtained
   322 ** from [sqlite3_open()], [sqlite3_open16()], or
   323 ** [sqlite3_open_v2()], and not previously closed.
   324 ** ^Calling sqlite3_close() or sqlite3_close_v2() with a NULL pointer
   325 ** argument is a harmless no-op.
   326 */
   327 SQLITE_API int sqlite3_close(sqlite3*);
   328 SQLITE_API int sqlite3_close_v2(sqlite3*);
   329 
   330 /*
   331 ** The type for a callback function.
   332 ** This is legacy and deprecated.  It is included for historical
   333 ** compatibility and is not documented.
   334 */
   335 typedef int (*sqlite3_callback)(void*,int,char**, char**);
   336 
   337 /*
   338 ** CAPI3REF: One-Step Query Execution Interface
   339 ** METHOD: sqlite3
   340 **
   341 ** The sqlite3_exec() interface is a convenience wrapper around
   342 ** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],
   343 ** that allows an application to run multiple statements of SQL
   344 ** without having to use a lot of C code. 
   345 **
   346 ** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
   347 ** semicolon-separate SQL statements passed into its 2nd argument,
   348 ** in the context of the [database connection] passed in as its 1st
   349 ** argument.  ^If the callback function of the 3rd argument to
   350 ** sqlite3_exec() is not NULL, then it is invoked for each result row
   351 ** coming out of the evaluated SQL statements.  ^The 4th argument to
   352 ** sqlite3_exec() is relayed through to the 1st argument of each
   353 ** callback invocation.  ^If the callback pointer to sqlite3_exec()
   354 ** is NULL, then no callback is ever invoked and result rows are
   355 ** ignored.
   356 **
   357 ** ^If an error occurs while evaluating the SQL statements passed into
   358 ** sqlite3_exec(), then execution of the current statement stops and
   359 ** subsequent statements are skipped.  ^If the 5th parameter to sqlite3_exec()
   360 ** is not NULL then any error message is written into memory obtained
   361 ** from [sqlite3_malloc()] and passed back through the 5th parameter.
   362 ** To avoid memory leaks, the application should invoke [sqlite3_free()]
   363 ** on error message strings returned through the 5th parameter of
   364 ** sqlite3_exec() after the error message string is no longer needed.
   365 ** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
   366 ** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
   367 ** NULL before returning.
   368 **
   369 ** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()
   370 ** routine returns SQLITE_ABORT without invoking the callback again and
   371 ** without running any subsequent SQL statements.
   372 **
   373 ** ^The 2nd argument to the sqlite3_exec() callback function is the
   374 ** number of columns in the result.  ^The 3rd argument to the sqlite3_exec()
   375 ** callback is an array of pointers to strings obtained as if from
   376 ** [sqlite3_column_text()], one for each column.  ^If an element of a
   377 ** result row is NULL then the corresponding string pointer for the
   378 ** sqlite3_exec() callback is a NULL pointer.  ^The 4th argument to the
   379 ** sqlite3_exec() callback is an array of pointers to strings where each
   380 ** entry represents the name of corresponding result column as obtained
   381 ** from [sqlite3_column_name()].
   382 **
   383 ** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer
   384 ** to an empty string, or a pointer that contains only whitespace and/or 
   385 ** SQL comments, then no SQL statements are evaluated and the database
   386 ** is not changed.
   387 **
   388 ** Restrictions:
   389 **
   390 ** <ul>
   391 ** <li> The application must ensure that the 1st parameter to sqlite3_exec()
   392 **      is a valid and open [database connection].
   393 ** <li> The application must not close the [database connection] specified by
   394 **      the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
   395 ** <li> The application must not modify the SQL statement text passed into
   396 **      the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.
   397 ** </ul>
   398 */
   399 SQLITE_API int sqlite3_exec(
   400   sqlite3*,                                  /* An open database */
   401   const char *sql,                           /* SQL to be evaluated */
   402   int (*callback)(void*,int,char**,char**),  /* Callback function */
   403   void *,                                    /* 1st argument to callback */
   404   char **errmsg                              /* Error msg written here */
   405 );
   406 
   407 /*
   408 ** CAPI3REF: Result Codes
   409 ** KEYWORDS: {result code definitions}
   410 **
   411 ** Many SQLite functions return an integer result code from the set shown
   412 ** here in order to indicate success or failure.
   413 **
   414 ** New error codes may be added in future versions of SQLite.
   415 **
   416 ** See also: [extended result code definitions]
   417 */
   418 #define SQLITE_OK           0   /* Successful result */
   419 /* beginning-of-error-codes */
   420 #define SQLITE_ERROR        1   /* SQL error or missing database */
   421 #define SQLITE_INTERNAL     2   /* Internal logic error in SQLite */
   422 #define SQLITE_PERM         3   /* Access permission denied */
   423 #define SQLITE_ABORT        4   /* Callback routine requested an abort */
   424 #define SQLITE_BUSY         5   /* The database file is locked */
   425 #define SQLITE_LOCKED       6   /* A table in the database is locked */
   426 #define SQLITE_NOMEM        7   /* A malloc() failed */
   427 #define SQLITE_READONLY     8   /* Attempt to write a readonly database */
   428 #define SQLITE_INTERRUPT    9   /* Operation terminated by sqlite3_interrupt()*/
   429 #define SQLITE_IOERR       10   /* Some kind of disk I/O error occurred */
   430 #define SQLITE_CORRUPT     11   /* The database disk image is malformed */
   431 #define SQLITE_NOTFOUND    12   /* Unknown opcode in sqlite3_file_control() */
   432 #define SQLITE_FULL        13   /* Insertion failed because database is full */
   433 #define SQLITE_CANTOPEN    14   /* Unable to open the database file */
   434 #define SQLITE_PROTOCOL    15   /* Database lock protocol error */
   435 #define SQLITE_EMPTY       16   /* Database is empty */
   436 #define SQLITE_SCHEMA      17   /* The database schema changed */
   437 #define SQLITE_TOOBIG      18   /* String or BLOB exceeds size limit */
   438 #define SQLITE_CONSTRAINT  19   /* Abort due to constraint violation */
   439 #define SQLITE_MISMATCH    20   /* Data type mismatch */
   440 #define SQLITE_MISUSE      21   /* Library used incorrectly */
   441 #define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
   442 #define SQLITE_AUTH        23   /* Authorization denied */
   443 #define SQLITE_FORMAT      24   /* Auxiliary database format error */
   444 #define SQLITE_RANGE       25   /* 2nd parameter to sqlite3_bind out of range */
   445 #define SQLITE_NOTADB      26   /* File opened that is not a database file */
   446 #define SQLITE_NOTICE      27   /* Notifications from sqlite3_log() */
   447 #define SQLITE_WARNING     28   /* Warnings from sqlite3_log() */
   448 #define SQLITE_ROW         100  /* sqlite3_step() has another row ready */
   449 #define SQLITE_DONE        101  /* sqlite3_step() has finished executing */
   450 /* end-of-error-codes */
   451 
   452 /*
   453 ** CAPI3REF: Extended Result Codes
   454 ** KEYWORDS: {extended result code definitions}
   455 **
   456 ** In its default configuration, SQLite API routines return one of 30 integer
   457 ** [result codes].  However, experience has shown that many of
   458 ** these result codes are too coarse-grained.  They do not provide as
   459 ** much information about problems as programmers might like.  In an effort to
   460 ** address this, newer versions of SQLite (version 3.3.8 [dateof:3.3.8]
   461 ** and later) include
   462 ** support for additional result codes that provide more detailed information
   463 ** about errors. These [extended result codes] are enabled or disabled
   464 ** on a per database connection basis using the
   465 ** [sqlite3_extended_result_codes()] API.  Or, the extended code for
   466 ** the most recent error can be obtained using
   467 ** [sqlite3_extended_errcode()].
   468 */
   469 #define SQLITE_IOERR_READ              (SQLITE_IOERR | (1<<8))
   470 #define SQLITE_IOERR_SHORT_READ        (SQLITE_IOERR | (2<<8))
   471 #define SQLITE_IOERR_WRITE             (SQLITE_IOERR | (3<<8))
   472 #define SQLITE_IOERR_FSYNC             (SQLITE_IOERR | (4<<8))
   473 #define SQLITE_IOERR_DIR_FSYNC         (SQLITE_IOERR | (5<<8))
   474 #define SQLITE_IOERR_TRUNCATE          (SQLITE_IOERR | (6<<8))
   475 #define SQLITE_IOERR_FSTAT             (SQLITE_IOERR | (7<<8))
   476 #define SQLITE_IOERR_UNLOCK            (SQLITE_IOERR | (8<<8))
   477 #define SQLITE_IOERR_RDLOCK            (SQLITE_IOERR | (9<<8))
   478 #define SQLITE_IOERR_DELETE            (SQLITE_IOERR | (10<<8))
   479 #define SQLITE_IOERR_BLOCKED           (SQLITE_IOERR | (11<<8))
   480 #define SQLITE_IOERR_NOMEM             (SQLITE_IOERR | (12<<8))
   481 #define SQLITE_IOERR_ACCESS            (SQLITE_IOERR | (13<<8))
   482 #define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
   483 #define SQLITE_IOERR_LOCK              (SQLITE_IOERR | (15<<8))
   484 #define SQLITE_IOERR_CLOSE             (SQLITE_IOERR | (16<<8))
   485 #define SQLITE_IOERR_DIR_CLOSE         (SQLITE_IOERR | (17<<8))
   486 #define SQLITE_IOERR_SHMOPEN           (SQLITE_IOERR | (18<<8))
   487 #define SQLITE_IOERR_SHMSIZE           (SQLITE_IOERR | (19<<8))
   488 #define SQLITE_IOERR_SHMLOCK           (SQLITE_IOERR | (20<<8))
   489 #define SQLITE_IOERR_SHMMAP            (SQLITE_IOERR | (21<<8))
   490 #define SQLITE_IOERR_SEEK              (SQLITE_IOERR | (22<<8))
   491 #define SQLITE_IOERR_DELETE_NOENT      (SQLITE_IOERR | (23<<8))
   492 #define SQLITE_IOERR_MMAP              (SQLITE_IOERR | (24<<8))
   493 #define SQLITE_IOERR_GETTEMPPATH       (SQLITE_IOERR | (25<<8))
   494 #define SQLITE_IOERR_CONVPATH          (SQLITE_IOERR | (26<<8))
   495 #define SQLITE_IOERR_VNODE             (SQLITE_IOERR | (27<<8))
   496 #define SQLITE_IOERR_AUTH              (SQLITE_IOERR | (28<<8))
   497 #define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
   498 #define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
   499 #define SQLITE_BUSY_SNAPSHOT           (SQLITE_BUSY   |  (2<<8))
   500 #define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
   501 #define SQLITE_CANTOPEN_ISDIR          (SQLITE_CANTOPEN | (2<<8))
   502 #define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
   503 #define SQLITE_CANTOPEN_CONVPATH       (SQLITE_CANTOPEN | (4<<8))
   504 #define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
   505 #define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
   506 #define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))
   507 #define SQLITE_READONLY_ROLLBACK       (SQLITE_READONLY | (3<<8))
   508 #define SQLITE_READONLY_DBMOVED        (SQLITE_READONLY | (4<<8))
   509 #define SQLITE_ABORT_ROLLBACK          (SQLITE_ABORT | (2<<8))
   510 #define SQLITE_CONSTRAINT_CHECK        (SQLITE_CONSTRAINT | (1<<8))
   511 #define SQLITE_CONSTRAINT_COMMITHOOK   (SQLITE_CONSTRAINT | (2<<8))
   512 #define SQLITE_CONSTRAINT_FOREIGNKEY   (SQLITE_CONSTRAINT | (3<<8))
   513 #define SQLITE_CONSTRAINT_FUNCTION     (SQLITE_CONSTRAINT | (4<<8))
   514 #define SQLITE_CONSTRAINT_NOTNULL      (SQLITE_CONSTRAINT | (5<<8))
   515 #define SQLITE_CONSTRAINT_PRIMARYKEY   (SQLITE_CONSTRAINT | (6<<8))
   516 #define SQLITE_CONSTRAINT_TRIGGER      (SQLITE_CONSTRAINT | (7<<8))
   517 #define SQLITE_CONSTRAINT_UNIQUE       (SQLITE_CONSTRAINT | (8<<8))
   518 #define SQLITE_CONSTRAINT_VTAB         (SQLITE_CONSTRAINT | (9<<8))
   519 #define SQLITE_CONSTRAINT_ROWID        (SQLITE_CONSTRAINT |(10<<8))
   520 #define SQLITE_NOTICE_RECOVER_WAL      (SQLITE_NOTICE | (1<<8))
   521 #define SQLITE_NOTICE_RECOVER_ROLLBACK (SQLITE_NOTICE | (2<<8))
   522 #define SQLITE_WARNING_AUTOINDEX       (SQLITE_WARNING | (1<<8))
   523 #define SQLITE_AUTH_USER               (SQLITE_AUTH | (1<<8))
   524 #define SQLITE_OK_LOAD_PERMANENTLY     (SQLITE_OK | (1<<8))
   525 
   526 /*
   527 ** CAPI3REF: Flags For File Open Operations
   528 **
   529 ** These bit values are intended for use in the
   530 ** 3rd parameter to the [sqlite3_open_v2()] interface and
   531 ** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
   532 */
   533 #define SQLITE_OPEN_READONLY         0x00000001  /* Ok for sqlite3_open_v2() */
   534 #define SQLITE_OPEN_READWRITE        0x00000002  /* Ok for sqlite3_open_v2() */
   535 #define SQLITE_OPEN_CREATE           0x00000004  /* Ok for sqlite3_open_v2() */
   536 #define SQLITE_OPEN_DELETEONCLOSE    0x00000008  /* VFS only */
   537 #define SQLITE_OPEN_EXCLUSIVE        0x00000010  /* VFS only */
   538 #define SQLITE_OPEN_AUTOPROXY        0x00000020  /* VFS only */
   539 #define SQLITE_OPEN_URI              0x00000040  /* Ok for sqlite3_open_v2() */
   540 #define SQLITE_OPEN_MEMORY           0x00000080  /* Ok for sqlite3_open_v2() */
   541 #define SQLITE_OPEN_MAIN_DB          0x00000100  /* VFS only */
   542 #define SQLITE_OPEN_TEMP_DB          0x00000200  /* VFS only */
   543 #define SQLITE_OPEN_TRANSIENT_DB     0x00000400  /* VFS only */
   544 #define SQLITE_OPEN_MAIN_JOURNAL     0x00000800  /* VFS only */
   545 #define SQLITE_OPEN_TEMP_JOURNAL     0x00001000  /* VFS only */
   546 #define SQLITE_OPEN_SUBJOURNAL       0x00002000  /* VFS only */
   547 #define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */
   548 #define SQLITE_OPEN_NOMUTEX          0x00008000  /* Ok for sqlite3_open_v2() */
   549 #define SQLITE_OPEN_FULLMUTEX        0x00010000  /* Ok for sqlite3_open_v2() */
   550 #define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
   551 #define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */
   552 #define SQLITE_OPEN_WAL              0x00080000  /* VFS only */
   553 
   554 /* Reserved:                         0x00F00000 */
   555 
   556 /*
   557 ** CAPI3REF: Device Characteristics
   558 **
   559 ** The xDeviceCharacteristics method of the [sqlite3_io_methods]
   560 ** object returns an integer which is a vector of these
   561 ** bit values expressing I/O characteristics of the mass storage
   562 ** device that holds the file that the [sqlite3_io_methods]
   563 ** refers to.
   564 **
   565 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
   566 ** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
   567 ** mean that writes of blocks that are nnn bytes in size and
   568 ** are aligned to an address which is an integer multiple of
   569 ** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
   570 ** that when data is appended to a file, the data is appended
   571 ** first then the size of the file is extended, never the other
   572 ** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
   573 ** information is written to disk in the same order as calls
   574 ** to xWrite().  The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that
   575 ** after reboot following a crash or power loss, the only bytes in a
   576 ** file that were written at the application level might have changed
   577 ** and that adjacent bytes, even bytes within the same sector are
   578 ** guaranteed to be unchanged.  The SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
   579 ** flag indicates that a file cannot be deleted when open.  The
   580 ** SQLITE_IOCAP_IMMUTABLE flag indicates that the file is on
   581 ** read-only media and cannot be changed even by processes with
   582 ** elevated privileges.
   583 */
   584 #define SQLITE_IOCAP_ATOMIC                 0x00000001
   585 #define SQLITE_IOCAP_ATOMIC512              0x00000002
   586 #define SQLITE_IOCAP_ATOMIC1K               0x00000004
   587 #define SQLITE_IOCAP_ATOMIC2K               0x00000008
   588 #define SQLITE_IOCAP_ATOMIC4K               0x00000010
   589 #define SQLITE_IOCAP_ATOMIC8K               0x00000020
   590 #define SQLITE_IOCAP_ATOMIC16K              0x00000040
   591 #define SQLITE_IOCAP_ATOMIC32K              0x00000080
   592 #define SQLITE_IOCAP_ATOMIC64K              0x00000100
   593 #define SQLITE_IOCAP_SAFE_APPEND            0x00000200
   594 #define SQLITE_IOCAP_SEQUENTIAL             0x00000400
   595 #define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN  0x00000800
   596 #define SQLITE_IOCAP_POWERSAFE_OVERWRITE    0x00001000
   597 #define SQLITE_IOCAP_IMMUTABLE              0x00002000
   598 
   599 /*
   600 ** CAPI3REF: File Locking Levels
   601 **
   602 ** SQLite uses one of these integer values as the second
   603 ** argument to calls it makes to the xLock() and xUnlock() methods
   604 ** of an [sqlite3_io_methods] object.
   605 */
   606 #define SQLITE_LOCK_NONE          0
   607 #define SQLITE_LOCK_SHARED        1
   608 #define SQLITE_LOCK_RESERVED      2
   609 #define SQLITE_LOCK_PENDING       3
   610 #define SQLITE_LOCK_EXCLUSIVE     4
   611 
   612 /*
   613 ** CAPI3REF: Synchronization Type Flags
   614 **
   615 ** When SQLite invokes the xSync() method of an
   616 ** [sqlite3_io_methods] object it uses a combination of
   617 ** these integer values as the second argument.
   618 **
   619 ** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
   620 ** sync operation only needs to flush data to mass storage.  Inode
   621 ** information need not be flushed. If the lower four bits of the flag
   622 ** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.
   623 ** If the lower four bits equal SQLITE_SYNC_FULL, that means
   624 ** to use Mac OS X style fullsync instead of fsync().
   625 **
   626 ** Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags
   627 ** with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL
   628 ** settings.  The [synchronous pragma] determines when calls to the
   629 ** xSync VFS method occur and applies uniformly across all platforms.
   630 ** The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how
   631 ** energetic or rigorous or forceful the sync operations are and
   632 ** only make a difference on Mac OSX for the default SQLite code.
   633 ** (Third-party VFS implementations might also make the distinction
   634 ** between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the
   635 ** operating systems natively supported by SQLite, only Mac OSX
   636 ** cares about the difference.)
   637 */
   638 #define SQLITE_SYNC_NORMAL        0x00002
   639 #define SQLITE_SYNC_FULL          0x00003
   640 #define SQLITE_SYNC_DATAONLY      0x00010
   641 
   642 /*
   643 ** CAPI3REF: OS Interface Open File Handle
   644 **
   645 ** An [sqlite3_file] object represents an open file in the 
   646 ** [sqlite3_vfs | OS interface layer].  Individual OS interface
   647 ** implementations will
   648 ** want to subclass this object by appending additional fields
   649 ** for their own use.  The pMethods entry is a pointer to an
   650 ** [sqlite3_io_methods] object that defines methods for performing
   651 ** I/O operations on the open file.
   652 */
   653 typedef struct sqlite3_file sqlite3_file;
   654 struct sqlite3_file {
   655   const struct sqlite3_io_methods *pMethods;  /* Methods for an open file */
   656 };
   657 
   658 /*
   659 ** CAPI3REF: OS Interface File Virtual Methods Object
   660 **
   661 ** Every file opened by the [sqlite3_vfs.xOpen] method populates an
   662 ** [sqlite3_file] object (or, more commonly, a subclass of the
   663 ** [sqlite3_file] object) with a pointer to an instance of this object.
   664 ** This object defines the methods used to perform various operations
   665 ** against the open file represented by the [sqlite3_file] object.
   666 **
   667 ** If the [sqlite3_vfs.xOpen] method sets the sqlite3_file.pMethods element 
   668 ** to a non-NULL pointer, then the sqlite3_io_methods.xClose method
   669 ** may be invoked even if the [sqlite3_vfs.xOpen] reported that it failed.  The
   670 ** only way to prevent a call to xClose following a failed [sqlite3_vfs.xOpen]
   671 ** is for the [sqlite3_vfs.xOpen] to set the sqlite3_file.pMethods element
   672 ** to NULL.
   673 **
   674 ** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
   675 ** [SQLITE_SYNC_FULL].  The first choice is the normal fsync().
   676 ** The second choice is a Mac OS X style fullsync.  The [SQLITE_SYNC_DATAONLY]
   677 ** flag may be ORed in to indicate that only the data of the file
   678 ** and not its inode needs to be synced.
   679 **
   680 ** The integer values to xLock() and xUnlock() are one of
   681 ** <ul>
   682 ** <li> [SQLITE_LOCK_NONE],
   683 ** <li> [SQLITE_LOCK_SHARED],
   684 ** <li> [SQLITE_LOCK_RESERVED],
   685 ** <li> [SQLITE_LOCK_PENDING], or
   686 ** <li> [SQLITE_LOCK_EXCLUSIVE].
   687 ** </ul>
   688 ** xLock() increases the lock. xUnlock() decreases the lock.
   689 ** The xCheckReservedLock() method checks whether any database connection,
   690 ** either in this process or in some other process, is holding a RESERVED,
   691 ** PENDING, or EXCLUSIVE lock on the file.  It returns true
   692 ** if such a lock exists and false otherwise.
   693 **
   694 ** The xFileControl() method is a generic interface that allows custom
   695 ** VFS implementations to directly control an open file using the
   696 ** [sqlite3_file_control()] interface.  The second "op" argument is an
   697 ** integer opcode.  The third argument is a generic pointer intended to
   698 ** point to a structure that may contain arguments or space in which to
   699 ** write return values.  Potential uses for xFileControl() might be
   700 ** functions to enable blocking locks with timeouts, to change the
   701 ** locking strategy (for example to use dot-file locks), to inquire
   702 ** about the status of a lock, or to break stale locks.  The SQLite
   703 ** core reserves all opcodes less than 100 for its own use.
   704 ** A [file control opcodes | list of opcodes] less than 100 is available.
   705 ** Applications that define a custom xFileControl method should use opcodes
   706 ** greater than 100 to avoid conflicts.  VFS implementations should
   707 ** return [SQLITE_NOTFOUND] for file control opcodes that they do not
   708 ** recognize.
   709 **
   710 ** The xSectorSize() method returns the sector size of the
   711 ** device that underlies the file.  The sector size is the
   712 ** minimum write that can be performed without disturbing
   713 ** other bytes in the file.  The xDeviceCharacteristics()
   714 ** method returns a bit vector describing behaviors of the
   715 ** underlying device:
   716 **
   717 ** <ul>
   718 ** <li> [SQLITE_IOCAP_ATOMIC]
   719 ** <li> [SQLITE_IOCAP_ATOMIC512]
   720 ** <li> [SQLITE_IOCAP_ATOMIC1K]
   721 ** <li> [SQLITE_IOCAP_ATOMIC2K]
   722 ** <li> [SQLITE_IOCAP_ATOMIC4K]
   723 ** <li> [SQLITE_IOCAP_ATOMIC8K]
   724 ** <li> [SQLITE_IOCAP_ATOMIC16K]
   725 ** <li> [SQLITE_IOCAP_ATOMIC32K]
   726 ** <li> [SQLITE_IOCAP_ATOMIC64K]
   727 ** <li> [SQLITE_IOCAP_SAFE_APPEND]
   728 ** <li> [SQLITE_IOCAP_SEQUENTIAL]
   729 ** <li> [SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN]
   730 ** <li> [SQLITE_IOCAP_POWERSAFE_OVERWRITE]
   731 ** <li> [SQLITE_IOCAP_IMMUTABLE]
   732 ** </ul>
   733 **
   734 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
   735 ** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
   736 ** mean that writes of blocks that are nnn bytes in size and
   737 ** are aligned to an address which is an integer multiple of
   738 ** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
   739 ** that when data is appended to a file, the data is appended
   740 ** first then the size of the file is extended, never the other
   741 ** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
   742 ** information is written to disk in the same order as calls
   743 ** to xWrite().
   744 **
   745 ** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
   746 ** in the unread portions of the buffer with zeros.  A VFS that
   747 ** fails to zero-fill short reads might seem to work.  However,
   748 ** failure to zero-fill short reads will eventually lead to
   749 ** database corruption.
   750 */
   751 typedef struct sqlite3_io_methods sqlite3_io_methods;
   752 struct sqlite3_io_methods {
   753   int iVersion;
   754   int (*xClose)(sqlite3_file*);
   755   int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
   756   int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
   757   int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
   758   int (*xSync)(sqlite3_file*, int flags);
   759   int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
   760   int (*xLock)(sqlite3_file*, int);
   761   int (*xUnlock)(sqlite3_file*, int);
   762   int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
   763   int (*xFileControl)(sqlite3_file*, int op, void *pArg);
   764   int (*xSectorSize)(sqlite3_file*);
   765   int (*xDeviceCharacteristics)(sqlite3_file*);
   766   /* Methods above are valid for version 1 */
   767   int (*xShmMap)(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
   768   int (*xShmLock)(sqlite3_file*, int offset, int n, int flags);
   769   void (*xShmBarrier)(sqlite3_file*);
   770   int (*xShmUnmap)(sqlite3_file*, int deleteFlag);
   771   /* Methods above are valid for version 2 */
   772   int (*xFetch)(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
   773   int (*xUnfetch)(sqlite3_file*, sqlite3_int64 iOfst, void *p);
   774   /* Methods above are valid for version 3 */
   775   /* Additional methods may be added in future releases */
   776 };
   777 
   778 /*
   779 ** CAPI3REF: Standard File Control Opcodes
   780 ** KEYWORDS: {file control opcodes} {file control opcode}
   781 **
   782 ** These integer constants are opcodes for the xFileControl method
   783 ** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
   784 ** interface.
   785 **
   786 ** <ul>
   787 ** <li>[[SQLITE_FCNTL_LOCKSTATE]]
   788 ** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging.  This
   789 ** opcode causes the xFileControl method to write the current state of
   790 ** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
   791 ** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
   792 ** into an integer that the pArg argument points to. This capability
   793 ** is used during testing and is only available when the SQLITE_TEST
   794 ** compile-time option is used.
   795 **
   796 ** <li>[[SQLITE_FCNTL_SIZE_HINT]]
   797 ** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
   798 ** layer a hint of how large the database file will grow to be during the
   799 ** current transaction.  This hint is not guaranteed to be accurate but it
   800 ** is often close.  The underlying VFS might choose to preallocate database
   801 ** file space based on this hint in order to help writes to the database
   802 ** file run faster.
   803 **
   804 ** <li>[[SQLITE_FCNTL_CHUNK_SIZE]]
   805 ** The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS
   806 ** extends and truncates the database file in chunks of a size specified
   807 ** by the user. The fourth argument to [sqlite3_file_control()] should 
   808 ** point to an integer (type int) containing the new chunk-size to use
   809 ** for the nominated database. Allocating database file space in large
   810 ** chunks (say 1MB at a time), may reduce file-system fragmentation and
   811 ** improve performance on some systems.
   812 **
   813 ** <li>[[SQLITE_FCNTL_FILE_POINTER]]
   814 ** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
   815 ** to the [sqlite3_file] object associated with a particular database
   816 ** connection.  See also [SQLITE_FCNTL_JOURNAL_POINTER].
   817 **
   818 ** <li>[[SQLITE_FCNTL_JOURNAL_POINTER]]
   819 ** The [SQLITE_FCNTL_JOURNAL_POINTER] opcode is used to obtain a pointer
   820 ** to the [sqlite3_file] object associated with the journal file (either
   821 ** the [rollback journal] or the [write-ahead log]) for a particular database
   822 ** connection.  See also [SQLITE_FCNTL_FILE_POINTER].
   823 **
   824 ** <li>[[SQLITE_FCNTL_SYNC_OMITTED]]
   825 ** No longer in use.
   826 **
   827 ** <li>[[SQLITE_FCNTL_SYNC]]
   828 ** The [SQLITE_FCNTL_SYNC] opcode is generated internally by SQLite and
   829 ** sent to the VFS immediately before the xSync method is invoked on a
   830 ** database file descriptor. Or, if the xSync method is not invoked 
   831 ** because the user has configured SQLite with 
   832 ** [PRAGMA synchronous | PRAGMA synchronous=OFF] it is invoked in place 
   833 ** of the xSync method. In most cases, the pointer argument passed with
   834 ** this file-control is NULL. However, if the database file is being synced
   835 ** as part of a multi-database commit, the argument points to a nul-terminated
   836 ** string containing the transactions master-journal file name. VFSes that 
   837 ** do not need this signal should silently ignore this opcode. Applications 
   838 ** should not call [sqlite3_file_control()] with this opcode as doing so may 
   839 ** disrupt the operation of the specialized VFSes that do require it.  
   840 **
   841 ** <li>[[SQLITE_FCNTL_COMMIT_PHASETWO]]
   842 ** The [SQLITE_FCNTL_COMMIT_PHASETWO] opcode is generated internally by SQLite
   843 ** and sent to the VFS after a transaction has been committed immediately
   844 ** but before the database is unlocked. VFSes that do not need this signal
   845 ** should silently ignore this opcode. Applications should not call
   846 ** [sqlite3_file_control()] with this opcode as doing so may disrupt the 
   847 ** operation of the specialized VFSes that do require it.  
   848 **
   849 ** <li>[[SQLITE_FCNTL_WIN32_AV_RETRY]]
   850 ** ^The [SQLITE_FCNTL_WIN32_AV_RETRY] opcode is used to configure automatic
   851 ** retry counts and intervals for certain disk I/O operations for the
   852 ** windows [VFS] in order to provide robustness in the presence of
   853 ** anti-virus programs.  By default, the windows VFS will retry file read,
   854 ** file write, and file delete operations up to 10 times, with a delay
   855 ** of 25 milliseconds before the first retry and with the delay increasing
   856 ** by an additional 25 milliseconds with each subsequent retry.  This
   857 ** opcode allows these two values (10 retries and 25 milliseconds of delay)
   858 ** to be adjusted.  The values are changed for all database connections
   859 ** within the same process.  The argument is a pointer to an array of two
   860 ** integers where the first integer is the new retry count and the second
   861 ** integer is the delay.  If either integer is negative, then the setting
   862 ** is not changed but instead the prior value of that setting is written
   863 ** into the array entry, allowing the current retry settings to be
   864 ** interrogated.  The zDbName parameter is ignored.
   865 **
   866 ** <li>[[SQLITE_FCNTL_PERSIST_WAL]]
   867 ** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the
   868 ** persistent [WAL | Write Ahead Log] setting.  By default, the auxiliary
   869 ** write ahead log and shared memory files used for transaction control
   870 ** are automatically deleted when the latest connection to the database
   871 ** closes.  Setting persistent WAL mode causes those files to persist after
   872 ** close.  Persisting the files is useful when other processes that do not
   873 ** have write permission on the directory containing the database file want
   874 ** to read the database file, as the WAL and shared memory files must exist
   875 ** in order for the database to be readable.  The fourth parameter to
   876 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
   877 ** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
   878 ** WAL mode.  If the integer is -1, then it is overwritten with the current
   879 ** WAL persistence setting.
   880 **
   881 ** <li>[[SQLITE_FCNTL_POWERSAFE_OVERWRITE]]
   882 ** ^The [SQLITE_FCNTL_POWERSAFE_OVERWRITE] opcode is used to set or query the
   883 ** persistent "powersafe-overwrite" or "PSOW" setting.  The PSOW setting
   884 ** determines the [SQLITE_IOCAP_POWERSAFE_OVERWRITE] bit of the
   885 ** xDeviceCharacteristics methods. The fourth parameter to
   886 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
   887 ** That integer is 0 to disable zero-damage mode or 1 to enable zero-damage
   888 ** mode.  If the integer is -1, then it is overwritten with the current
   889 ** zero-damage mode setting.
   890 **
   891 ** <li>[[SQLITE_FCNTL_OVERWRITE]]
   892 ** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
   893 ** a write transaction to indicate that, unless it is rolled back for some
   894 ** reason, the entire database file will be overwritten by the current 
   895 ** transaction. This is used by VACUUM operations.
   896 **
   897 ** <li>[[SQLITE_FCNTL_VFSNAME]]
   898 ** ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of
   899 ** all [VFSes] in the VFS stack.  The names are of all VFS shims and the
   900 ** final bottom-level VFS are written into memory obtained from 
   901 ** [sqlite3_malloc()] and the result is stored in the char* variable
   902 ** that the fourth parameter of [sqlite3_file_control()] points to.
   903 ** The caller is responsible for freeing the memory when done.  As with
   904 ** all file-control actions, there is no guarantee that this will actually
   905 ** do anything.  Callers should initialize the char* variable to a NULL
   906 ** pointer in case this file-control is not implemented.  This file-control
   907 ** is intended for diagnostic use only.
   908 **
   909 ** <li>[[SQLITE_FCNTL_VFS_POINTER]]
   910 ** ^The [SQLITE_FCNTL_VFS_POINTER] opcode finds a pointer to the top-level
   911 ** [VFSes] currently in use.  ^(The argument X in
   912 ** sqlite3_file_control(db,SQLITE_FCNTL_VFS_POINTER,X) must be
   913 ** of type "[sqlite3_vfs] **".  This opcodes will set *X
   914 ** to a pointer to the top-level VFS.)^
   915 ** ^When there are multiple VFS shims in the stack, this opcode finds the
   916 ** upper-most shim only.
   917 **
   918 ** <li>[[SQLITE_FCNTL_PRAGMA]]
   919 ** ^Whenever a [PRAGMA] statement is parsed, an [SQLITE_FCNTL_PRAGMA] 
   920 ** file control is sent to the open [sqlite3_file] object corresponding
   921 ** to the database file to which the pragma statement refers. ^The argument
   922 ** to the [SQLITE_FCNTL_PRAGMA] file control is an array of
   923 ** pointers to strings (char**) in which the second element of the array
   924 ** is the name of the pragma and the third element is the argument to the
   925 ** pragma or NULL if the pragma has no argument.  ^The handler for an
   926 ** [SQLITE_FCNTL_PRAGMA] file control can optionally make the first element
   927 ** of the char** argument point to a string obtained from [sqlite3_mprintf()]
   928 ** or the equivalent and that string will become the result of the pragma or
   929 ** the error message if the pragma fails. ^If the
   930 ** [SQLITE_FCNTL_PRAGMA] file control returns [SQLITE_NOTFOUND], then normal 
   931 ** [PRAGMA] processing continues.  ^If the [SQLITE_FCNTL_PRAGMA]
   932 ** file control returns [SQLITE_OK], then the parser assumes that the
   933 ** VFS has handled the PRAGMA itself and the parser generates a no-op
   934 ** prepared statement if result string is NULL, or that returns a copy
   935 ** of the result string if the string is non-NULL.
   936 ** ^If the [SQLITE_FCNTL_PRAGMA] file control returns
   937 ** any result code other than [SQLITE_OK] or [SQLITE_NOTFOUND], that means
   938 ** that the VFS encountered an error while handling the [PRAGMA] and the
   939 ** compilation of the PRAGMA fails with an error.  ^The [SQLITE_FCNTL_PRAGMA]
   940 ** file control occurs at the beginning of pragma statement analysis and so
   941 ** it is able to override built-in [PRAGMA] statements.
   942 **
   943 ** <li>[[SQLITE_FCNTL_BUSYHANDLER]]
   944 ** ^The [SQLITE_FCNTL_BUSYHANDLER]
   945 ** file-control may be invoked by SQLite on the database file handle
   946 ** shortly after it is opened in order to provide a custom VFS with access
   947 ** to the connections busy-handler callback. The argument is of type (void **)
   948 ** - an array of two (void *) values. The first (void *) actually points
   949 ** to a function of type (int (*)(void *)). In order to invoke the connections
   950 ** busy-handler, this function should be invoked with the second (void *) in
   951 ** the array as the only argument. If it returns non-zero, then the operation
   952 ** should be retried. If it returns zero, the custom VFS should abandon the
   953 ** current operation.
   954 **
   955 ** <li>[[SQLITE_FCNTL_TEMPFILENAME]]
   956 ** ^Application can invoke the [SQLITE_FCNTL_TEMPFILENAME] file-control
   957 ** to have SQLite generate a
   958 ** temporary filename using the same algorithm that is followed to generate
   959 ** temporary filenames for TEMP tables and other internal uses.  The
   960 ** argument should be a char** which will be filled with the filename
   961 ** written into memory obtained from [sqlite3_malloc()].  The caller should
   962 ** invoke [sqlite3_free()] on the result to avoid a memory leak.
   963 **
   964 ** <li>[[SQLITE_FCNTL_MMAP_SIZE]]
   965 ** The [SQLITE_FCNTL_MMAP_SIZE] file control is used to query or set the
   966 ** maximum number of bytes that will be used for memory-mapped I/O.
   967 ** The argument is a pointer to a value of type sqlite3_int64 that
   968 ** is an advisory maximum number of bytes in the file to memory map.  The
   969 ** pointer is overwritten with the old value.  The limit is not changed if
   970 ** the value originally pointed to is negative, and so the current limit 
   971 ** can be queried by passing in a pointer to a negative number.  This
   972 ** file-control is used internally to implement [PRAGMA mmap_size].
   973 **
   974 ** <li>[[SQLITE_FCNTL_TRACE]]
   975 ** The [SQLITE_FCNTL_TRACE] file control provides advisory information
   976 ** to the VFS about what the higher layers of the SQLite stack are doing.
   977 ** This file control is used by some VFS activity tracing [shims].
   978 ** The argument is a zero-terminated string.  Higher layers in the
   979 ** SQLite stack may generate instances of this file control if
   980 ** the [SQLITE_USE_FCNTL_TRACE] compile-time option is enabled.
   981 **
   982 ** <li>[[SQLITE_FCNTL_HAS_MOVED]]
   983 ** The [SQLITE_FCNTL_HAS_MOVED] file control interprets its argument as a
   984 ** pointer to an integer and it writes a boolean into that integer depending
   985 ** on whether or not the file has been renamed, moved, or deleted since it
   986 ** was first opened.
   987 **
   988 ** <li>[[SQLITE_FCNTL_WIN32_GET_HANDLE]]
   989 ** The [SQLITE_FCNTL_WIN32_GET_HANDLE] opcode can be used to obtain the
   990 ** underlying native file handle associated with a file handle.  This file
   991 ** control interprets its argument as a pointer to a native file handle and
   992 ** writes the resulting value there.
   993 **
   994 ** <li>[[SQLITE_FCNTL_WIN32_SET_HANDLE]]
   995 ** The [SQLITE_FCNTL_WIN32_SET_HANDLE] opcode is used for debugging.  This
   996 ** opcode causes the xFileControl method to swap the file handle with the one
   997 ** pointed to by the pArg argument.  This capability is used during testing
   998 ** and only needs to be supported when SQLITE_TEST is defined.
   999 **
  1000 ** <li>[[SQLITE_FCNTL_WAL_BLOCK]]
  1001 ** The [SQLITE_FCNTL_WAL_BLOCK] is a signal to the VFS layer that it might
  1002 ** be advantageous to block on the next WAL lock if the lock is not immediately
  1003 ** available.  The WAL subsystem issues this signal during rare
  1004 ** circumstances in order to fix a problem with priority inversion.
  1005 ** Applications should <em>not</em> use this file-control.
  1006 **
  1007 ** <li>[[SQLITE_FCNTL_ZIPVFS]]
  1008 ** The [SQLITE_FCNTL_ZIPVFS] opcode is implemented by zipvfs only. All other
  1009 ** VFS should return SQLITE_NOTFOUND for this opcode.
  1010 **
  1011 ** <li>[[SQLITE_FCNTL_RBU]]
  1012 ** The [SQLITE_FCNTL_RBU] opcode is implemented by the special VFS used by
  1013 ** the RBU extension only.  All other VFS should return SQLITE_NOTFOUND for
  1014 ** this opcode.  
  1015 ** </ul>
  1016 */
  1017 #define SQLITE_FCNTL_LOCKSTATE               1
  1018 #define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
  1019 #define SQLITE_FCNTL_SET_LOCKPROXYFILE       3
  1020 #define SQLITE_FCNTL_LAST_ERRNO              4
  1021 #define SQLITE_FCNTL_SIZE_HINT               5
  1022 #define SQLITE_FCNTL_CHUNK_SIZE              6
  1023 #define SQLITE_FCNTL_FILE_POINTER            7
  1024 #define SQLITE_FCNTL_SYNC_OMITTED            8
  1025 #define SQLITE_FCNTL_WIN32_AV_RETRY          9
  1026 #define SQLITE_FCNTL_PERSIST_WAL            10
  1027 #define SQLITE_FCNTL_OVERWRITE              11
  1028 #define SQLITE_FCNTL_VFSNAME                12
  1029 #define SQLITE_FCNTL_POWERSAFE_OVERWRITE    13
  1030 #define SQLITE_FCNTL_PRAGMA                 14
  1031 #define SQLITE_FCNTL_BUSYHANDLER            15
  1032 #define SQLITE_FCNTL_TEMPFILENAME           16
  1033 #define SQLITE_FCNTL_MMAP_SIZE              18
  1034 #define SQLITE_FCNTL_TRACE                  19
  1035 #define SQLITE_FCNTL_HAS_MOVED              20
  1036 #define SQLITE_FCNTL_SYNC                   21
  1037 #define SQLITE_FCNTL_COMMIT_PHASETWO        22
  1038 #define SQLITE_FCNTL_WIN32_SET_HANDLE       23
  1039 #define SQLITE_FCNTL_WAL_BLOCK              24
  1040 #define SQLITE_FCNTL_ZIPVFS                 25
  1041 #define SQLITE_FCNTL_RBU                    26
  1042 #define SQLITE_FCNTL_VFS_POINTER            27
  1043 #define SQLITE_FCNTL_JOURNAL_POINTER        28
  1044 #define SQLITE_FCNTL_WIN32_GET_HANDLE       29
  1045 #define SQLITE_FCNTL_PDB                    30
  1046 
  1047 /* deprecated names */
  1048 #define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
  1049 #define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
  1050 #define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO
  1051 
  1052 
  1053 /*
  1054 ** CAPI3REF: Mutex Handle
  1055 **
  1056 ** The mutex module within SQLite defines [sqlite3_mutex] to be an
  1057 ** abstract type for a mutex object.  The SQLite core never looks
  1058 ** at the internal representation of an [sqlite3_mutex].  It only
  1059 ** deals with pointers to the [sqlite3_mutex] object.
  1060 **
  1061 ** Mutexes are created using [sqlite3_mutex_alloc()].
  1062 */
  1063 typedef struct sqlite3_mutex sqlite3_mutex;
  1064 
  1065 /*
  1066 ** CAPI3REF: Loadable Extension Thunk
  1067 **
  1068 ** A pointer to the opaque sqlite3_api_routines structure is passed as
  1069 ** the third parameter to entry points of [loadable extensions].  This
  1070 ** structure must be typedefed in order to work around compiler warnings
  1071 ** on some platforms.
  1072 */
  1073 typedef struct sqlite3_api_routines sqlite3_api_routines;
  1074 
  1075 /*
  1076 ** CAPI3REF: OS Interface Object
  1077 **
  1078 ** An instance of the sqlite3_vfs object defines the interface between
  1079 ** the SQLite core and the underlying operating system.  The "vfs"
  1080 ** in the name of the object stands for "virtual file system".  See
  1081 ** the [VFS | VFS documentation] for further information.
  1082 **
  1083 ** The value of the iVersion field is initially 1 but may be larger in
  1084 ** future versions of SQLite.  Additional fields may be appended to this
  1085 ** object when the iVersion value is increased.  Note that the structure
  1086 ** of the sqlite3_vfs object changes in the transaction between
  1087 ** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not
  1088 ** modified.
  1089 **
  1090 ** The szOsFile field is the size of the subclassed [sqlite3_file]
  1091 ** structure used by this VFS.  mxPathname is the maximum length of
  1092 ** a pathname in this VFS.
  1093 **
  1094 ** Registered sqlite3_vfs objects are kept on a linked list formed by
  1095 ** the pNext pointer.  The [sqlite3_vfs_register()]
  1096 ** and [sqlite3_vfs_unregister()] interfaces manage this list
  1097 ** in a thread-safe way.  The [sqlite3_vfs_find()] interface
  1098 ** searches the list.  Neither the application code nor the VFS
  1099 ** implementation should use the pNext pointer.
  1100 **
  1101 ** The pNext field is the only field in the sqlite3_vfs
  1102 ** structure that SQLite will ever modify.  SQLite will only access
  1103 ** or modify this field while holding a particular static mutex.
  1104 ** The application should never modify anything within the sqlite3_vfs
  1105 ** object once the object has been registered.
  1106 **
  1107 ** The zName field holds the name of the VFS module.  The name must
  1108 ** be unique across all VFS modules.
  1109 **
  1110 ** [[sqlite3_vfs.xOpen]]
  1111 ** ^SQLite guarantees that the zFilename parameter to xOpen
  1112 ** is either a NULL pointer or string obtained
  1113 ** from xFullPathname() with an optional suffix added.
  1114 ** ^If a suffix is added to the zFilename parameter, it will
  1115 ** consist of a single "-" character followed by no more than
  1116 ** 11 alphanumeric and/or "-" characters.
  1117 ** ^SQLite further guarantees that
  1118 ** the string will be valid and unchanged until xClose() is
  1119 ** called. Because of the previous sentence,
  1120 ** the [sqlite3_file] can safely store a pointer to the
  1121 ** filename if it needs to remember the filename for some reason.
  1122 ** If the zFilename parameter to xOpen is a NULL pointer then xOpen
  1123 ** must invent its own temporary name for the file.  ^Whenever the 
  1124 ** xFilename parameter is NULL it will also be the case that the
  1125 ** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
  1126 **
  1127 ** The flags argument to xOpen() includes all bits set in
  1128 ** the flags argument to [sqlite3_open_v2()].  Or if [sqlite3_open()]
  1129 ** or [sqlite3_open16()] is used, then flags includes at least
  1130 ** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]. 
  1131 ** If xOpen() opens a file read-only then it sets *pOutFlags to
  1132 ** include [SQLITE_OPEN_READONLY].  Other bits in *pOutFlags may be set.
  1133 **
  1134 ** ^(SQLite will also add one of the following flags to the xOpen()
  1135 ** call, depending on the object being opened:
  1136 **
  1137 ** <ul>
  1138 ** <li>  [SQLITE_OPEN_MAIN_DB]
  1139 ** <li>  [SQLITE_OPEN_MAIN_JOURNAL]
  1140 ** <li>  [SQLITE_OPEN_TEMP_DB]
  1141 ** <li>  [SQLITE_OPEN_TEMP_JOURNAL]
  1142 ** <li>  [SQLITE_OPEN_TRANSIENT_DB]
  1143 ** <li>  [SQLITE_OPEN_SUBJOURNAL]
  1144 ** <li>  [SQLITE_OPEN_MASTER_JOURNAL]
  1145 ** <li>  [SQLITE_OPEN_WAL]
  1146 ** </ul>)^
  1147 **
  1148 ** The file I/O implementation can use the object type flags to
  1149 ** change the way it deals with files.  For example, an application
  1150 ** that does not care about crash recovery or rollback might make
  1151 ** the open of a journal file a no-op.  Writes to this journal would
  1152 ** also be no-ops, and any attempt to read the journal would return
  1153 ** SQLITE_IOERR.  Or the implementation might recognize that a database
  1154 ** file will be doing page-aligned sector reads and writes in a random
  1155 ** order and set up its I/O subsystem accordingly.
  1156 **
  1157 ** SQLite might also add one of the following flags to the xOpen method:
  1158 **
  1159 ** <ul>
  1160 ** <li> [SQLITE_OPEN_DELETEONCLOSE]
  1161 ** <li> [SQLITE_OPEN_EXCLUSIVE]
  1162 ** </ul>
  1163 **
  1164 ** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
  1165 ** deleted when it is closed.  ^The [SQLITE_OPEN_DELETEONCLOSE]
  1166 ** will be set for TEMP databases and their journals, transient
  1167 ** databases, and subjournals.
  1168 **
  1169 ** ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction
  1170 ** with the [SQLITE_OPEN_CREATE] flag, which are both directly
  1171 ** analogous to the O_EXCL and O_CREAT flags of the POSIX open()
  1172 ** API.  The SQLITE_OPEN_EXCLUSIVE flag, when paired with the 
  1173 ** SQLITE_OPEN_CREATE, is used to indicate that file should always
  1174 ** be created, and that it is an error if it already exists.
  1175 ** It is <i>not</i> used to indicate the file should be opened 
  1176 ** for exclusive access.
  1177 **
  1178 ** ^At least szOsFile bytes of memory are allocated by SQLite
  1179 ** to hold the  [sqlite3_file] structure passed as the third
  1180 ** argument to xOpen.  The xOpen method does not have to
  1181 ** allocate the structure; it should just fill it in.  Note that
  1182 ** the xOpen method must set the sqlite3_file.pMethods to either
  1183 ** a valid [sqlite3_io_methods] object or to NULL.  xOpen must do
  1184 ** this even if the open fails.  SQLite expects that the sqlite3_file.pMethods
  1185 ** element will be valid after xOpen returns regardless of the success
  1186 ** or failure of the xOpen call.
  1187 **
  1188 ** [[sqlite3_vfs.xAccess]]
  1189 ** ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
  1190 ** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
  1191 ** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
  1192 ** to test whether a file is at least readable.   The file can be a
  1193 ** directory.
  1194 **
  1195 ** ^SQLite will always allocate at least mxPathname+1 bytes for the
  1196 ** output buffer xFullPathname.  The exact size of the output buffer
  1197 ** is also passed as a parameter to both  methods. If the output buffer
  1198 ** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
  1199 ** handled as a fatal error by SQLite, vfs implementations should endeavor
  1200 ** to prevent this by setting mxPathname to a sufficiently large value.
  1201 **
  1202 ** The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64()
  1203 ** interfaces are not strictly a part of the filesystem, but they are
  1204 ** included in the VFS structure for completeness.
  1205 ** The xRandomness() function attempts to return nBytes bytes
  1206 ** of good-quality randomness into zOut.  The return value is
  1207 ** the actual number of bytes of randomness obtained.
  1208 ** The xSleep() method causes the calling thread to sleep for at
  1209 ** least the number of microseconds given.  ^The xCurrentTime()
  1210 ** method returns a Julian Day Number for the current date and time as
  1211 ** a floating point value.
  1212 ** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
  1213 ** Day Number multiplied by 86400000 (the number of milliseconds in 
  1214 ** a 24-hour day).  
  1215 ** ^SQLite will use the xCurrentTimeInt64() method to get the current
  1216 ** date and time if that method is available (if iVersion is 2 or 
  1217 ** greater and the function pointer is not NULL) and will fall back
  1218 ** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
  1219 **
  1220 ** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
  1221 ** are not used by the SQLite core.  These optional interfaces are provided
  1222 ** by some VFSes to facilitate testing of the VFS code. By overriding 
  1223 ** system calls with functions under its control, a test program can
  1224 ** simulate faults and error conditions that would otherwise be difficult
  1225 ** or impossible to induce.  The set of system calls that can be overridden
  1226 ** varies from one VFS to another, and from one version of the same VFS to the
  1227 ** next.  Applications that use these interfaces must be prepared for any
  1228 ** or all of these interfaces to be NULL or for their behavior to change
  1229 ** from one release to the next.  Applications must not attempt to access
  1230 ** any of these methods if the iVersion of the VFS is less than 3.
  1231 */
  1232 typedef struct sqlite3_vfs sqlite3_vfs;
  1233 typedef void (*sqlite3_syscall_ptr)(void);
  1234 struct sqlite3_vfs {
  1235   int iVersion;            /* Structure version number (currently 3) */
  1236   int szOsFile;            /* Size of subclassed sqlite3_file */
  1237   int mxPathname;          /* Maximum file pathname length */
  1238   sqlite3_vfs *pNext;      /* Next registered VFS */
  1239   const char *zName;       /* Name of this virtual file system */
  1240   void *pAppData;          /* Pointer to application-specific data */
  1241   int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
  1242                int flags, int *pOutFlags);
  1243   int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
  1244   int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
  1245   int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
  1246   void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
  1247   void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
  1248   void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
  1249   void (*xDlClose)(sqlite3_vfs*, void*);
  1250   int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
  1251   int (*xSleep)(sqlite3_vfs*, int microseconds);
  1252   int (*xCurrentTime)(sqlite3_vfs*, double*);
  1253   int (*xGetLastError)(sqlite3_vfs*, int, char *);
  1254   /*
  1255   ** The methods above are in version 1 of the sqlite_vfs object
  1256   ** definition.  Those that follow are added in version 2 or later
  1257   */
  1258   int (*xCurrentTimeInt64)(sqlite3_vfs*, sqlite3_int64*);
  1259   /*
  1260   ** The methods above are in versions 1 and 2 of the sqlite_vfs object.
  1261   ** Those below are for version 3 and greater.
  1262   */
  1263   int (*xSetSystemCall)(sqlite3_vfs*, const char *zName, sqlite3_syscall_ptr);
  1264   sqlite3_syscall_ptr (*xGetSystemCall)(sqlite3_vfs*, const char *zName);
  1265   const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
  1266   /*
  1267   ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
  1268   ** New fields may be appended in future versions.  The iVersion
  1269   ** value will increment whenever this happens. 
  1270   */
  1271 };
  1272 
  1273 /*
  1274 ** CAPI3REF: Flags for the xAccess VFS method
  1275 **
  1276 ** These integer constants can be used as the third parameter to
  1277 ** the xAccess method of an [sqlite3_vfs] object.  They determine
  1278 ** what kind of permissions the xAccess method is looking for.
  1279 ** With SQLITE_ACCESS_EXISTS, the xAccess method
  1280 ** simply checks whether the file exists.
  1281 ** With SQLITE_ACCESS_READWRITE, the xAccess method
  1282 ** checks whether the named directory is both readable and writable
  1283 ** (in other words, if files can be added, removed, and renamed within
  1284 ** the directory).
  1285 ** The SQLITE_ACCESS_READWRITE constant is currently used only by the
  1286 ** [temp_store_directory pragma], though this could change in a future
  1287 ** release of SQLite.
  1288 ** With SQLITE_ACCESS_READ, the xAccess method
  1289 ** checks whether the file is readable.  The SQLITE_ACCESS_READ constant is
  1290 ** currently unused, though it might be used in a future release of
  1291 ** SQLite.
  1292 */
  1293 #define SQLITE_ACCESS_EXISTS    0
  1294 #define SQLITE_ACCESS_READWRITE 1   /* Used by PRAGMA temp_store_directory */
  1295 #define SQLITE_ACCESS_READ      2   /* Unused */
  1296 
  1297 /*
  1298 ** CAPI3REF: Flags for the xShmLock VFS method
  1299 **
  1300 ** These integer constants define the various locking operations
  1301 ** allowed by the xShmLock method of [sqlite3_io_methods].  The
  1302 ** following are the only legal combinations of flags to the
  1303 ** xShmLock method:
  1304 **
  1305 ** <ul>
  1306 ** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_SHARED
  1307 ** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE
  1308 ** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED
  1309 ** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE
  1310 ** </ul>
  1311 **
  1312 ** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
  1313 ** was given on the corresponding lock.  
  1314 **
  1315 ** The xShmLock method can transition between unlocked and SHARED or
  1316 ** between unlocked and EXCLUSIVE.  It cannot transition between SHARED
  1317 ** and EXCLUSIVE.
  1318 */
  1319 #define SQLITE_SHM_UNLOCK       1
  1320 #define SQLITE_SHM_LOCK         2
  1321 #define SQLITE_SHM_SHARED       4
  1322 #define SQLITE_SHM_EXCLUSIVE    8
  1323 
  1324 /*
  1325 ** CAPI3REF: Maximum xShmLock index
  1326 **
  1327 ** The xShmLock method on [sqlite3_io_methods] may use values
  1328 ** between 0 and this upper bound as its "offset" argument.
  1329 ** The SQLite core will never attempt to acquire or release a
  1330 ** lock outside of this range
  1331 */
  1332 #define SQLITE_SHM_NLOCK        8
  1333 
  1334 
  1335 /*
  1336 ** CAPI3REF: Initialize The SQLite Library
  1337 **
  1338 ** ^The sqlite3_initialize() routine initializes the
  1339 ** SQLite library.  ^The sqlite3_shutdown() routine
  1340 ** deallocates any resources that were allocated by sqlite3_initialize().
  1341 ** These routines are designed to aid in process initialization and
  1342 ** shutdown on embedded systems.  Workstation applications using
  1343 ** SQLite normally do not need to invoke either of these routines.
  1344 **
  1345 ** A call to sqlite3_initialize() is an "effective" call if it is
  1346 ** the first time sqlite3_initialize() is invoked during the lifetime of
  1347 ** the process, or if it is the first time sqlite3_initialize() is invoked
  1348 ** following a call to sqlite3_shutdown().  ^(Only an effective call
  1349 ** of sqlite3_initialize() does any initialization.  All other calls
  1350 ** are harmless no-ops.)^
  1351 **
  1352 ** A call to sqlite3_shutdown() is an "effective" call if it is the first
  1353 ** call to sqlite3_shutdown() since the last sqlite3_initialize().  ^(Only
  1354 ** an effective call to sqlite3_shutdown() does any deinitialization.
  1355 ** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^
  1356 **
  1357 ** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()
  1358 ** is not.  The sqlite3_shutdown() interface must only be called from a
  1359 ** single thread.  All open [database connections] must be closed and all
  1360 ** other SQLite resources must be deallocated prior to invoking
  1361 ** sqlite3_shutdown().
  1362 **
  1363 ** Among other things, ^sqlite3_initialize() will invoke
  1364 ** sqlite3_os_init().  Similarly, ^sqlite3_shutdown()
  1365 ** will invoke sqlite3_os_end().
  1366 **
  1367 ** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.
  1368 ** ^If for some reason, sqlite3_initialize() is unable to initialize
  1369 ** the library (perhaps it is unable to allocate a needed resource such
  1370 ** as a mutex) it returns an [error code] other than [SQLITE_OK].
  1371 **
  1372 ** ^The sqlite3_initialize() routine is called internally by many other
  1373 ** SQLite interfaces so that an application usually does not need to
  1374 ** invoke sqlite3_initialize() directly.  For example, [sqlite3_open()]
  1375 ** calls sqlite3_initialize() so the SQLite library will be automatically
  1376 ** initialized when [sqlite3_open()] is called if it has not be initialized
  1377 ** already.  ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
  1378 ** compile-time option, then the automatic calls to sqlite3_initialize()
  1379 ** are omitted and the application must call sqlite3_initialize() directly
  1380 ** prior to using any other SQLite interface.  For maximum portability,
  1381 ** it is recommended that applications always invoke sqlite3_initialize()
  1382 ** directly prior to using any other SQLite interface.  Future releases
  1383 ** of SQLite may require this.  In other words, the behavior exhibited
  1384 ** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
  1385 ** default behavior in some future release of SQLite.
  1386 **
  1387 ** The sqlite3_os_init() routine does operating-system specific
  1388 ** initialization of the SQLite library.  The sqlite3_os_end()
  1389 ** routine undoes the effect of sqlite3_os_init().  Typical tasks
  1390 ** performed by these routines include allocation or deallocation
  1391 ** of static resources, initialization of global variables,
  1392 ** setting up a default [sqlite3_vfs] module, or setting up
  1393 ** a default configuration using [sqlite3_config()].
  1394 **
  1395 ** The application should never invoke either sqlite3_os_init()
  1396 ** or sqlite3_os_end() directly.  The application should only invoke
  1397 ** sqlite3_initialize() and sqlite3_shutdown().  The sqlite3_os_init()
  1398 ** interface is called automatically by sqlite3_initialize() and
  1399 ** sqlite3_os_end() is called by sqlite3_shutdown().  Appropriate
  1400 ** implementations for sqlite3_os_init() and sqlite3_os_end()
  1401 ** are built into SQLite when it is compiled for Unix, Windows, or OS/2.
  1402 ** When [custom builds | built for other platforms]
  1403 ** (using the [SQLITE_OS_OTHER=1] compile-time
  1404 ** option) the application must supply a suitable implementation for
  1405 ** sqlite3_os_init() and sqlite3_os_end().  An application-supplied
  1406 ** implementation of sqlite3_os_init() or sqlite3_os_end()
  1407 ** must return [SQLITE_OK] on success and some other [error code] upon
  1408 ** failure.
  1409 */
  1410 SQLITE_API int sqlite3_initialize(void);
  1411 SQLITE_API int sqlite3_shutdown(void);
  1412 SQLITE_API int sqlite3_os_init(void);
  1413 SQLITE_API int sqlite3_os_end(void);
  1414 
  1415 /*
  1416 ** CAPI3REF: Configuring The SQLite Library
  1417 **
  1418 ** The sqlite3_config() interface is used to make global configuration
  1419 ** changes to SQLite in order to tune SQLite to the specific needs of
  1420 ** the application.  The default configuration is recommended for most
  1421 ** applications and so this routine is usually not necessary.  It is
  1422 ** provided to support rare applications with unusual needs.
  1423 **
  1424 ** <b>The sqlite3_config() interface is not threadsafe. The application
  1425 ** must ensure that no other SQLite interfaces are invoked by other
  1426 ** threads while sqlite3_config() is running.</b>
  1427 **
  1428 ** The sqlite3_config() interface
  1429 ** may only be invoked prior to library initialization using
  1430 ** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
  1431 ** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
  1432 ** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.
  1433 ** Note, however, that ^sqlite3_config() can be called as part of the
  1434 ** implementation of an application-defined [sqlite3_os_init()].
  1435 **
  1436 ** The first argument to sqlite3_config() is an integer
  1437 ** [configuration option] that determines
  1438 ** what property of SQLite is to be configured.  Subsequent arguments
  1439 ** vary depending on the [configuration option]
  1440 ** in the first argument.
  1441 **
  1442 ** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
  1443 ** ^If the option is unknown or SQLite is unable to set the option
  1444 ** then this routine returns a non-zero [error code].
  1445 */
  1446 SQLITE_API int sqlite3_config(int, ...);
  1447 
  1448 /*
  1449 ** CAPI3REF: Configure database connections
  1450 ** METHOD: sqlite3
  1451 **
  1452 ** The sqlite3_db_config() interface is used to make configuration
  1453 ** changes to a [database connection].  The interface is similar to
  1454 ** [sqlite3_config()] except that the changes apply to a single
  1455 ** [database connection] (specified in the first argument).
  1456 **
  1457 ** The second argument to sqlite3_db_config(D,V,...)  is the
  1458 ** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code 
  1459 ** that indicates what aspect of the [database connection] is being configured.
  1460 ** Subsequent arguments vary depending on the configuration verb.
  1461 **
  1462 ** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
  1463 ** the call is considered successful.
  1464 */
  1465 SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);
  1466 
  1467 /*
  1468 ** CAPI3REF: Memory Allocation Routines
  1469 **
  1470 ** An instance of this object defines the interface between SQLite
  1471 ** and low-level memory allocation routines.
  1472 **
  1473 ** This object is used in only one place in the SQLite interface.
  1474 ** A pointer to an instance of this object is the argument to
  1475 ** [sqlite3_config()] when the configuration option is
  1476 ** [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC].  
  1477 ** By creating an instance of this object
  1478 ** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])
  1479 ** during configuration, an application can specify an alternative
  1480 ** memory allocation subsystem for SQLite to use for all of its
  1481 ** dynamic memory needs.
  1482 **
  1483 ** Note that SQLite comes with several [built-in memory allocators]
  1484 ** that are perfectly adequate for the overwhelming majority of applications
  1485 ** and that this object is only useful to a tiny minority of applications
  1486 ** with specialized memory allocation requirements.  This object is
  1487 ** also used during testing of SQLite in order to specify an alternative
  1488 ** memory allocator that simulates memory out-of-memory conditions in
  1489 ** order to verify that SQLite recovers gracefully from such
  1490 ** conditions.
  1491 **
  1492 ** The xMalloc, xRealloc, and xFree methods must work like the
  1493 ** malloc(), realloc() and free() functions from the standard C library.
  1494 ** ^SQLite guarantees that the second argument to
  1495 ** xRealloc is always a value returned by a prior call to xRoundup.
  1496 **
  1497 ** xSize should return the allocated size of a memory allocation
  1498 ** previously obtained from xMalloc or xRealloc.  The allocated size
  1499 ** is always at least as big as the requested size but may be larger.
  1500 **
  1501 ** The xRoundup method returns what would be the allocated size of
  1502 ** a memory allocation given a particular requested size.  Most memory
  1503 ** allocators round up memory allocations at least to the next multiple
  1504 ** of 8.  Some allocators round up to a larger multiple or to a power of 2.
  1505 ** Every memory allocation request coming in through [sqlite3_malloc()]
  1506 ** or [sqlite3_realloc()] first calls xRoundup.  If xRoundup returns 0, 
  1507 ** that causes the corresponding memory allocation to fail.
  1508 **
  1509 ** The xInit method initializes the memory allocator.  For example,
  1510 ** it might allocate any require mutexes or initialize internal data
  1511 ** structures.  The xShutdown method is invoked (indirectly) by
  1512 ** [sqlite3_shutdown()] and should deallocate any resources acquired
  1513 ** by xInit.  The pAppData pointer is used as the only parameter to
  1514 ** xInit and xShutdown.
  1515 **
  1516 ** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes
  1517 ** the xInit method, so the xInit method need not be threadsafe.  The
  1518 ** xShutdown method is only called from [sqlite3_shutdown()] so it does
  1519 ** not need to be threadsafe either.  For all other methods, SQLite
  1520 ** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the
  1521 ** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which
  1522 ** it is by default) and so the methods are automatically serialized.
  1523 ** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other
  1524 ** methods must be threadsafe or else make their own arrangements for
  1525 ** serialization.
  1526 **
  1527 ** SQLite will never invoke xInit() more than once without an intervening
  1528 ** call to xShutdown().
  1529 */
  1530 typedef struct sqlite3_mem_methods sqlite3_mem_methods;
  1531 struct sqlite3_mem_methods {
  1532   void *(*xMalloc)(int);         /* Memory allocation function */
  1533   void (*xFree)(void*);          /* Free a prior allocation */
  1534   void *(*xRealloc)(void*,int);  /* Resize an allocation */
  1535   int (*xSize)(void*);           /* Return the size of an allocation */
  1536   int (*xRoundup)(int);          /* Round up request size to allocation size */
  1537   int (*xInit)(void*);           /* Initialize the memory allocator */
  1538   void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
  1539   void *pAppData;                /* Argument to xInit() and xShutdown() */
  1540 };
  1541 
  1542 /*
  1543 ** CAPI3REF: Configuration Options
  1544 ** KEYWORDS: {configuration option}
  1545 **
  1546 ** These constants are the available integer configuration options that
  1547 ** can be passed as the first argument to the [sqlite3_config()] interface.
  1548 **
  1549 ** New configuration options may be added in future releases of SQLite.
  1550 ** Existing configuration options might be discontinued.  Applications
  1551 ** should check the return code from [sqlite3_config()] to make sure that
  1552 ** the call worked.  The [sqlite3_config()] interface will return a
  1553 ** non-zero [error code] if a discontinued or unsupported configuration option
  1554 ** is invoked.
  1555 **
  1556 ** <dl>
  1557 ** [[SQLITE_CONFIG_SINGLETHREAD]] <dt>SQLITE_CONFIG_SINGLETHREAD</dt>
  1558 ** <dd>There are no arguments to this option.  ^This option sets the
  1559 ** [threading mode] to Single-thread.  In other words, it disables
  1560 ** all mutexing and puts SQLite into a mode where it can only be used
  1561 ** by a single thread.   ^If SQLite is compiled with
  1562 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1563 ** it is not possible to change the [threading mode] from its default
  1564 ** value of Single-thread and so [sqlite3_config()] will return 
  1565 ** [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD
  1566 ** configuration option.</dd>
  1567 **
  1568 ** [[SQLITE_CONFIG_MULTITHREAD]] <dt>SQLITE_CONFIG_MULTITHREAD</dt>
  1569 ** <dd>There are no arguments to this option.  ^This option sets the
  1570 ** [threading mode] to Multi-thread.  In other words, it disables
  1571 ** mutexing on [database connection] and [prepared statement] objects.
  1572 ** The application is responsible for serializing access to
  1573 ** [database connections] and [prepared statements].  But other mutexes
  1574 ** are enabled so that SQLite will be safe to use in a multi-threaded
  1575 ** environment as long as no two threads attempt to use the same
  1576 ** [database connection] at the same time.  ^If SQLite is compiled with
  1577 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1578 ** it is not possible to set the Multi-thread [threading mode] and
  1579 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
  1580 ** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>
  1581 **
  1582 ** [[SQLITE_CONFIG_SERIALIZED]] <dt>SQLITE_CONFIG_SERIALIZED</dt>
  1583 ** <dd>There are no arguments to this option.  ^This option sets the
  1584 ** [threading mode] to Serialized. In other words, this option enables
  1585 ** all mutexes including the recursive
  1586 ** mutexes on [database connection] and [prepared statement] objects.
  1587 ** In this mode (which is the default when SQLite is compiled with
  1588 ** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
  1589 ** to [database connections] and [prepared statements] so that the
  1590 ** application is free to use the same [database connection] or the
  1591 ** same [prepared statement] in different threads at the same time.
  1592 ** ^If SQLite is compiled with
  1593 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1594 ** it is not possible to set the Serialized [threading mode] and
  1595 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
  1596 ** SQLITE_CONFIG_SERIALIZED configuration option.</dd>
  1597 **
  1598 ** [[SQLITE_CONFIG_MALLOC]] <dt>SQLITE_CONFIG_MALLOC</dt>
  1599 ** <dd> ^(The SQLITE_CONFIG_MALLOC option takes a single argument which is 
  1600 ** a pointer to an instance of the [sqlite3_mem_methods] structure.
  1601 ** The argument specifies
  1602 ** alternative low-level memory allocation routines to be used in place of
  1603 ** the memory allocation routines built into SQLite.)^ ^SQLite makes
  1604 ** its own private copy of the content of the [sqlite3_mem_methods] structure
  1605 ** before the [sqlite3_config()] call returns.</dd>
  1606 **
  1607 ** [[SQLITE_CONFIG_GETMALLOC]] <dt>SQLITE_CONFIG_GETMALLOC</dt>
  1608 ** <dd> ^(The SQLITE_CONFIG_GETMALLOC option takes a single argument which
  1609 ** is a pointer to an instance of the [sqlite3_mem_methods] structure.
  1610 ** The [sqlite3_mem_methods]
  1611 ** structure is filled with the currently defined memory allocation routines.)^
  1612 ** This option can be used to overload the default memory allocation
  1613 ** routines with a wrapper that simulations memory allocation failure or
  1614 ** tracks memory usage, for example. </dd>
  1615 **
  1616 ** [[SQLITE_CONFIG_MEMSTATUS]] <dt>SQLITE_CONFIG_MEMSTATUS</dt>
  1617 ** <dd> ^The SQLITE_CONFIG_MEMSTATUS option takes single argument of type int,
  1618 ** interpreted as a boolean, which enables or disables the collection of
  1619 ** memory allocation statistics. ^(When memory allocation statistics are
  1620 ** disabled, the following SQLite interfaces become non-operational:
  1621 **   <ul>
  1622 **   <li> [sqlite3_memory_used()]
  1623 **   <li> [sqlite3_memory_highwater()]
  1624 **   <li> [sqlite3_soft_heap_limit64()]
  1625 **   <li> [sqlite3_status64()]
  1626 **   </ul>)^
  1627 ** ^Memory allocation statistics are enabled by default unless SQLite is
  1628 ** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
  1629 ** allocation statistics are disabled by default.
  1630 ** </dd>
  1631 **
  1632 ** [[SQLITE_CONFIG_SCRATCH]] <dt>SQLITE_CONFIG_SCRATCH</dt>
  1633 ** <dd> ^The SQLITE_CONFIG_SCRATCH option specifies a static memory buffer
  1634 ** that SQLite can use for scratch memory.  ^(There are three arguments
  1635 ** to SQLITE_CONFIG_SCRATCH:  A pointer an 8-byte
  1636 ** aligned memory buffer from which the scratch allocations will be
  1637 ** drawn, the size of each scratch allocation (sz),
  1638 ** and the maximum number of scratch allocations (N).)^
  1639 ** The first argument must be a pointer to an 8-byte aligned buffer
  1640 ** of at least sz*N bytes of memory.
  1641 ** ^SQLite will not use more than one scratch buffers per thread.
  1642 ** ^SQLite will never request a scratch buffer that is more than 6
  1643 ** times the database page size.
  1644 ** ^If SQLite needs needs additional
  1645 ** scratch memory beyond what is provided by this configuration option, then 
  1646 ** [sqlite3_malloc()] will be used to obtain the memory needed.<p>
  1647 ** ^When the application provides any amount of scratch memory using
  1648 ** SQLITE_CONFIG_SCRATCH, SQLite avoids unnecessary large
  1649 ** [sqlite3_malloc|heap allocations].
  1650 ** This can help [Robson proof|prevent memory allocation failures] due to heap
  1651 ** fragmentation in low-memory embedded systems.
  1652 ** </dd>
  1653 **
  1654 ** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
  1655 ** <dd> ^The SQLITE_CONFIG_PAGECACHE option specifies a memory pool
  1656 ** that SQLite can use for the database page cache with the default page
  1657 ** cache implementation.  
  1658 ** This configuration option is a no-op if an application-define page
  1659 ** cache implementation is loaded using the [SQLITE_CONFIG_PCACHE2].
  1660 ** ^There are three arguments to SQLITE_CONFIG_PAGECACHE: A pointer to
  1661 ** 8-byte aligned memory (pMem), the size of each page cache line (sz),
  1662 ** and the number of cache lines (N).
  1663 ** The sz argument should be the size of the largest database page
  1664 ** (a power of two between 512 and 65536) plus some extra bytes for each
  1665 ** page header.  ^The number of extra bytes needed by the page header
  1666 ** can be determined using [SQLITE_CONFIG_PCACHE_HDRSZ].
  1667 ** ^It is harmless, apart from the wasted memory,
  1668 ** for the sz parameter to be larger than necessary.  The pMem
  1669 ** argument must be either a NULL pointer or a pointer to an 8-byte
  1670 ** aligned block of memory of at least sz*N bytes, otherwise
  1671 ** subsequent behavior is undefined.
  1672 ** ^When pMem is not NULL, SQLite will strive to use the memory provided
  1673 ** to satisfy page cache needs, falling back to [sqlite3_malloc()] if
  1674 ** a page cache line is larger than sz bytes or if all of the pMem buffer
  1675 ** is exhausted.
  1676 ** ^If pMem is NULL and N is non-zero, then each database connection
  1677 ** does an initial bulk allocation for page cache memory
  1678 ** from [sqlite3_malloc()] sufficient for N cache lines if N is positive or
  1679 ** of -1024*N bytes if N is negative, . ^If additional
  1680 ** page cache memory is needed beyond what is provided by the initial
  1681 ** allocation, then SQLite goes to [sqlite3_malloc()] separately for each
  1682 ** additional cache line. </dd>
  1683 **
  1684 ** [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt>
  1685 ** <dd> ^The SQLITE_CONFIG_HEAP option specifies a static memory buffer 
  1686 ** that SQLite will use for all of its dynamic memory allocation needs
  1687 ** beyond those provided for by [SQLITE_CONFIG_SCRATCH] and
  1688 ** [SQLITE_CONFIG_PAGECACHE].
  1689 ** ^The SQLITE_CONFIG_HEAP option is only available if SQLite is compiled
  1690 ** with either [SQLITE_ENABLE_MEMSYS3] or [SQLITE_ENABLE_MEMSYS5] and returns
  1691 ** [SQLITE_ERROR] if invoked otherwise.
  1692 ** ^There are three arguments to SQLITE_CONFIG_HEAP:
  1693 ** An 8-byte aligned pointer to the memory,
  1694 ** the number of bytes in the memory buffer, and the minimum allocation size.
  1695 ** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
  1696 ** to using its default memory allocator (the system malloc() implementation),
  1697 ** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
  1698 ** memory pointer is not NULL then the alternative memory
  1699 ** allocator is engaged to handle all of SQLites memory allocation needs.
  1700 ** The first pointer (the memory pointer) must be aligned to an 8-byte
  1701 ** boundary or subsequent behavior of SQLite will be undefined.
  1702 ** The minimum allocation size is capped at 2**12. Reasonable values
  1703 ** for the minimum allocation size are 2**5 through 2**8.</dd>
  1704 **
  1705 ** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
  1706 ** <dd> ^(The SQLITE_CONFIG_MUTEX option takes a single argument which is a
  1707 ** pointer to an instance of the [sqlite3_mutex_methods] structure.
  1708 ** The argument specifies alternative low-level mutex routines to be used
  1709 ** in place the mutex routines built into SQLite.)^  ^SQLite makes a copy of
  1710 ** the content of the [sqlite3_mutex_methods] structure before the call to
  1711 ** [sqlite3_config()] returns. ^If SQLite is compiled with
  1712 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1713 ** the entire mutexing subsystem is omitted from the build and hence calls to
  1714 ** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
  1715 ** return [SQLITE_ERROR].</dd>
  1716 **
  1717 ** [[SQLITE_CONFIG_GETMUTEX]] <dt>SQLITE_CONFIG_GETMUTEX</dt>
  1718 ** <dd> ^(The SQLITE_CONFIG_GETMUTEX option takes a single argument which
  1719 ** is a pointer to an instance of the [sqlite3_mutex_methods] structure.  The
  1720 ** [sqlite3_mutex_methods]
  1721 ** structure is filled with the currently defined mutex routines.)^
  1722 ** This option can be used to overload the default mutex allocation
  1723 ** routines with a wrapper used to track mutex usage for performance
  1724 ** profiling or testing, for example.   ^If SQLite is compiled with
  1725 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1726 ** the entire mutexing subsystem is omitted from the build and hence calls to
  1727 ** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will
  1728 ** return [SQLITE_ERROR].</dd>
  1729 **
  1730 ** [[SQLITE_CONFIG_LOOKASIDE]] <dt>SQLITE_CONFIG_LOOKASIDE</dt>
  1731 ** <dd> ^(The SQLITE_CONFIG_LOOKASIDE option takes two arguments that determine
  1732 ** the default size of lookaside memory on each [database connection].
  1733 ** The first argument is the
  1734 ** size of each lookaside buffer slot and the second is the number of
  1735 ** slots allocated to each database connection.)^  ^(SQLITE_CONFIG_LOOKASIDE
  1736 ** sets the <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]
  1737 ** option to [sqlite3_db_config()] can be used to change the lookaside
  1738 ** configuration on individual connections.)^ </dd>
  1739 **
  1740 ** [[SQLITE_CONFIG_PCACHE2]] <dt>SQLITE_CONFIG_PCACHE2</dt>
  1741 ** <dd> ^(The SQLITE_CONFIG_PCACHE2 option takes a single argument which is 
  1742 ** a pointer to an [sqlite3_pcache_methods2] object.  This object specifies
  1743 ** the interface to a custom page cache implementation.)^
  1744 ** ^SQLite makes a copy of the [sqlite3_pcache_methods2] object.</dd>
  1745 **
  1746 ** [[SQLITE_CONFIG_GETPCACHE2]] <dt>SQLITE_CONFIG_GETPCACHE2</dt>
  1747 ** <dd> ^(The SQLITE_CONFIG_GETPCACHE2 option takes a single argument which
  1748 ** is a pointer to an [sqlite3_pcache_methods2] object.  SQLite copies of
  1749 ** the current page cache implementation into that object.)^ </dd>
  1750 **
  1751 ** [[SQLITE_CONFIG_LOG]] <dt>SQLITE_CONFIG_LOG</dt>
  1752 ** <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite
  1753 ** global [error log].
  1754 ** (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
  1755 ** function with a call signature of void(*)(void*,int,const char*), 
  1756 ** and a pointer to void. ^If the function pointer is not NULL, it is
  1757 ** invoked by [sqlite3_log()] to process each logging event.  ^If the
  1758 ** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
  1759 ** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
  1760 ** passed through as the first parameter to the application-defined logger
  1761 ** function whenever that function is invoked.  ^The second parameter to
  1762 ** the logger function is a copy of the first parameter to the corresponding
  1763 ** [sqlite3_log()] call and is intended to be a [result code] or an
  1764 ** [extended result code].  ^The third parameter passed to the logger is
  1765 ** log message after formatting via [sqlite3_snprintf()].
  1766 ** The SQLite logging interface is not reentrant; the logger function
  1767 ** supplied by the application must not invoke any SQLite interface.
  1768 ** In a multi-threaded application, the application-defined logger
  1769 ** function must be threadsafe. </dd>
  1770 **
  1771 ** [[SQLITE_CONFIG_URI]] <dt>SQLITE_CONFIG_URI
  1772 ** <dd>^(The SQLITE_CONFIG_URI option takes a single argument of type int.
  1773 ** If non-zero, then URI handling is globally enabled. If the parameter is zero,
  1774 ** then URI handling is globally disabled.)^ ^If URI handling is globally
  1775 ** enabled, all filenames passed to [sqlite3_open()], [sqlite3_open_v2()],
  1776 ** [sqlite3_open16()] or
  1777 ** specified as part of [ATTACH] commands are interpreted as URIs, regardless
  1778 ** of whether or not the [SQLITE_OPEN_URI] flag is set when the database
  1779 ** connection is opened. ^If it is globally disabled, filenames are
  1780 ** only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the
  1781 ** database connection is opened. ^(By default, URI handling is globally
  1782 ** disabled. The default value may be changed by compiling with the
  1783 ** [SQLITE_USE_URI] symbol defined.)^
  1784 **
  1785 ** [[SQLITE_CONFIG_COVERING_INDEX_SCAN]] <dt>SQLITE_CONFIG_COVERING_INDEX_SCAN
  1786 ** <dd>^The SQLITE_CONFIG_COVERING_INDEX_SCAN option takes a single integer
  1787 ** argument which is interpreted as a boolean in order to enable or disable
  1788 ** the use of covering indices for full table scans in the query optimizer.
  1789 ** ^The default setting is determined
  1790 ** by the [SQLITE_ALLOW_COVERING_INDEX_SCAN] compile-time option, or is "on"
  1791 ** if that compile-time option is omitted.
  1792 ** The ability to disable the use of covering indices for full table scans
  1793 ** is because some incorrectly coded legacy applications might malfunction
  1794 ** when the optimization is enabled.  Providing the ability to
  1795 ** disable the optimization allows the older, buggy application code to work
  1796 ** without change even with newer versions of SQLite.
  1797 **
  1798 ** [[SQLITE_CONFIG_PCACHE]] [[SQLITE_CONFIG_GETPCACHE]]
  1799 ** <dt>SQLITE_CONFIG_PCACHE and SQLITE_CONFIG_GETPCACHE
  1800 ** <dd> These options are obsolete and should not be used by new code.
  1801 ** They are retained for backwards compatibility but are now no-ops.
  1802 ** </dd>
  1803 **
  1804 ** [[SQLITE_CONFIG_SQLLOG]]
  1805 ** <dt>SQLITE_CONFIG_SQLLOG
  1806 ** <dd>This option is only available if sqlite is compiled with the
  1807 ** [SQLITE_ENABLE_SQLLOG] pre-processor macro defined. The first argument should
  1808 ** be a pointer to a function of type void(*)(void*,sqlite3*,const char*, int).
  1809 ** The second should be of type (void*). The callback is invoked by the library
  1810 ** in three separate circumstances, identified by the value passed as the
  1811 ** fourth parameter. If the fourth parameter is 0, then the database connection
  1812 ** passed as the second argument has just been opened. The third argument
  1813 ** points to a buffer containing the name of the main database file. If the
  1814 ** fourth parameter is 1, then the SQL statement that the third parameter
  1815 ** points to has just been executed. Or, if the fourth parameter is 2, then
  1816 ** the connection being passed as the second parameter is being closed. The
  1817 ** third parameter is passed NULL In this case.  An example of using this
  1818 ** configuration option can be seen in the "test_sqllog.c" source file in
  1819 ** the canonical SQLite source tree.</dd>
  1820 **
  1821 ** [[SQLITE_CONFIG_MMAP_SIZE]]
  1822 ** <dt>SQLITE_CONFIG_MMAP_SIZE
  1823 ** <dd>^SQLITE_CONFIG_MMAP_SIZE takes two 64-bit integer (sqlite3_int64) values
  1824 ** that are the default mmap size limit (the default setting for
  1825 ** [PRAGMA mmap_size]) and the maximum allowed mmap size limit.
  1826 ** ^The default setting can be overridden by each database connection using
  1827 ** either the [PRAGMA mmap_size] command, or by using the
  1828 ** [SQLITE_FCNTL_MMAP_SIZE] file control.  ^(The maximum allowed mmap size
  1829 ** will be silently truncated if necessary so that it does not exceed the
  1830 ** compile-time maximum mmap size set by the
  1831 ** [SQLITE_MAX_MMAP_SIZE] compile-time option.)^
  1832 ** ^If either argument to this option is negative, then that argument is
  1833 ** changed to its compile-time default.
  1834 **
  1835 ** [[SQLITE_CONFIG_WIN32_HEAPSIZE]]
  1836 ** <dt>SQLITE_CONFIG_WIN32_HEAPSIZE
  1837 ** <dd>^The SQLITE_CONFIG_WIN32_HEAPSIZE option is only available if SQLite is
  1838 ** compiled for Windows with the [SQLITE_WIN32_MALLOC] pre-processor macro
  1839 ** defined. ^SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value
  1840 ** that specifies the maximum size of the created heap.
  1841 **
  1842 ** [[SQLITE_CONFIG_PCACHE_HDRSZ]]
  1843 ** <dt>SQLITE_CONFIG_PCACHE_HDRSZ
  1844 ** <dd>^The SQLITE_CONFIG_PCACHE_HDRSZ option takes a single parameter which
  1845 ** is a pointer to an integer and writes into that integer the number of extra
  1846 ** bytes per page required for each page in [SQLITE_CONFIG_PAGECACHE].
  1847 ** The amount of extra space required can change depending on the compiler,
  1848 ** target platform, and SQLite version.
  1849 **
  1850 ** [[SQLITE_CONFIG_PMASZ]]
  1851 ** <dt>SQLITE_CONFIG_PMASZ
  1852 ** <dd>^The SQLITE_CONFIG_PMASZ option takes a single parameter which
  1853 ** is an unsigned integer and sets the "Minimum PMA Size" for the multithreaded
  1854 ** sorter to that integer.  The default minimum PMA Size is set by the
  1855 ** [SQLITE_SORTER_PMASZ] compile-time option.  New threads are launched
  1856 ** to help with sort operations when multithreaded sorting
  1857 ** is enabled (using the [PRAGMA threads] command) and the amount of content
  1858 ** to be sorted exceeds the page size times the minimum of the
  1859 ** [PRAGMA cache_size] setting and this value.
  1860 **
  1861 ** [[SQLITE_CONFIG_STMTJRNL_SPILL]]
  1862 ** <dt>SQLITE_CONFIG_STMTJRNL_SPILL
  1863 ** <dd>^The SQLITE_CONFIG_STMTJRNL_SPILL option takes a single parameter which
  1864 ** becomes the [statement journal] spill-to-disk threshold.  
  1865 ** [Statement journals] are held in memory until their size (in bytes)
  1866 ** exceeds this threshold, at which point they are written to disk.
  1867 ** Or if the threshold is -1, statement journals are always held
  1868 ** exclusively in memory.
  1869 ** Since many statement journals never become large, setting the spill
  1870 ** threshold to a value such as 64KiB can greatly reduce the amount of
  1871 ** I/O required to support statement rollback.
  1872 ** The default value for this setting is controlled by the
  1873 ** [SQLITE_STMTJRNL_SPILL] compile-time option.
  1874 ** </dl>
  1875 */
  1876 #define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
  1877 #define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
  1878 #define SQLITE_CONFIG_SERIALIZED    3  /* nil */
  1879 #define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
  1880 #define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
  1881 #define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
  1882 #define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
  1883 #define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
  1884 #define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
  1885 #define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
  1886 #define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
  1887 /* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 
  1888 #define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
  1889 #define SQLITE_CONFIG_PCACHE       14  /* no-op */
  1890 #define SQLITE_CONFIG_GETPCACHE    15  /* no-op */
  1891 #define SQLITE_CONFIG_LOG          16  /* xFunc, void* */
  1892 #define SQLITE_CONFIG_URI          17  /* int */
  1893 #define SQLITE_CONFIG_PCACHE2      18  /* sqlite3_pcache_methods2* */
  1894 #define SQLITE_CONFIG_GETPCACHE2   19  /* sqlite3_pcache_methods2* */
  1895 #define SQLITE_CONFIG_COVERING_INDEX_SCAN 20  /* int */
  1896 #define SQLITE_CONFIG_SQLLOG       21  /* xSqllog, void* */
  1897 #define SQLITE_CONFIG_MMAP_SIZE    22  /* sqlite3_int64, sqlite3_int64 */
  1898 #define SQLITE_CONFIG_WIN32_HEAPSIZE      23  /* int nByte */
  1899 #define SQLITE_CONFIG_PCACHE_HDRSZ        24  /* int *psz */
  1900 #define SQLITE_CONFIG_PMASZ               25  /* unsigned int szPma */
  1901 #define SQLITE_CONFIG_STMTJRNL_SPILL      26  /* int nByte */
  1902 
  1903 /*
  1904 ** CAPI3REF: Database Connection Configuration Options
  1905 **
  1906 ** These constants are the available integer configuration options that
  1907 ** can be passed as the second argument to the [sqlite3_db_config()] interface.
  1908 **
  1909 ** New configuration options may be added in future releases of SQLite.
  1910 ** Existing configuration options might be discontinued.  Applications
  1911 ** should check the return code from [sqlite3_db_config()] to make sure that
  1912 ** the call worked.  ^The [sqlite3_db_config()] interface will return a
  1913 ** non-zero [error code] if a discontinued or unsupported configuration option
  1914 ** is invoked.
  1915 **
  1916 ** <dl>
  1917 ** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
  1918 ** <dd> ^This option takes three additional arguments that determine the 
  1919 ** [lookaside memory allocator] configuration for the [database connection].
  1920 ** ^The first argument (the third parameter to [sqlite3_db_config()] is a
  1921 ** pointer to a memory buffer to use for lookaside memory.
  1922 ** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
  1923 ** may be NULL in which case SQLite will allocate the
  1924 ** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
  1925 ** size of each lookaside buffer slot.  ^The third argument is the number of
  1926 ** slots.  The size of the buffer in the first argument must be greater than
  1927 ** or equal to the product of the second and third arguments.  The buffer
  1928 ** must be aligned to an 8-byte boundary.  ^If the second argument to
  1929 ** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally
  1930 ** rounded down to the next smaller multiple of 8.  ^(The lookaside memory
  1931 ** configuration for a database connection can only be changed when that
  1932 ** connection is not currently using lookaside memory, or in other words
  1933 ** when the "current value" returned by
  1934 ** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
  1935 ** Any attempt to change the lookaside memory configuration when lookaside
  1936 ** memory is in use leaves the configuration unchanged and returns 
  1937 ** [SQLITE_BUSY].)^</dd>
  1938 **
  1939 ** <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>
  1940 ** <dd> ^This option is used to enable or disable the enforcement of
  1941 ** [foreign key constraints].  There should be two additional arguments.
  1942 ** The first argument is an integer which is 0 to disable FK enforcement,
  1943 ** positive to enable FK enforcement or negative to leave FK enforcement
  1944 ** unchanged.  The second parameter is a pointer to an integer into which
  1945 ** is written 0 or 1 to indicate whether FK enforcement is off or on
  1946 ** following this call.  The second parameter may be a NULL pointer, in
  1947 ** which case the FK enforcement setting is not reported back. </dd>
  1948 **
  1949 ** <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>
  1950 ** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
  1951 ** There should be two additional arguments.
  1952 ** The first argument is an integer which is 0 to disable triggers,
  1953 ** positive to enable triggers or negative to leave the setting unchanged.
  1954 ** The second parameter is a pointer to an integer into which
  1955 ** is written 0 or 1 to indicate whether triggers are disabled or enabled
  1956 ** following this call.  The second parameter may be a NULL pointer, in
  1957 ** which case the trigger setting is not reported back. </dd>
  1958 **
  1959 ** <dt>SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER</dt>
  1960 ** <dd> ^This option is used to enable or disable the two-argument
  1961 ** version of the [fts3_tokenizer()] function which is part of the
  1962 ** [FTS3] full-text search engine extension.
  1963 ** There should be two additional arguments.
  1964 ** The first argument is an integer which is 0 to disable fts3_tokenizer() or
  1965 ** positive to enable fts3_tokenizer() or negative to leave the setting
  1966 ** unchanged.
  1967 ** The second parameter is a pointer to an integer into which
  1968 ** is written 0 or 1 to indicate whether fts3_tokenizer is disabled or enabled
  1969 ** following this call.  The second parameter may be a NULL pointer, in
  1970 ** which case the new setting is not reported back. </dd>
  1971 **
  1972 ** <dt>SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION</dt>
  1973 ** <dd> ^This option is used to enable or disable the [sqlite3_load_extension()]
  1974 ** interface independently of the [load_extension()] SQL function.
  1975 ** The [sqlite3_enable_load_extension()] API enables or disables both the
  1976 ** C-API [sqlite3_load_extension()] and the SQL function [load_extension()].
  1977 ** There should be two additional arguments.
  1978 ** When the first argument to this interface is 1, then only the C-API is
  1979 ** enabled and the SQL function remains disabled.  If the first argument to
  1980 ** this interface is 0, then both the C-API and the SQL function are disabled.
  1981 ** If the first argument is -1, then no changes are made to state of either the
  1982 ** C-API or the SQL function.
  1983 ** The second parameter is a pointer to an integer into which
  1984 ** is written 0 or 1 to indicate whether [sqlite3_load_extension()] interface
  1985 ** is disabled or enabled following this call.  The second parameter may
  1986 ** be a NULL pointer, in which case the new setting is not reported back.
  1987 ** </dd>
  1988 **
  1989 ** <dt>SQLITE_DBCONFIG_MAINDBNAME</dt>
  1990 ** <dd> ^This option is used to change the name of the "main" database
  1991 ** schema.  ^The sole argument is a pointer to a constant UTF8 string
  1992 ** which will become the new schema name in place of "main".  ^SQLite
  1993 ** does not make a copy of the new main schema name string, so the application
  1994 ** must ensure that the argument passed into this DBCONFIG option is unchanged
  1995 ** until after the database connection closes.
  1996 ** </dd>
  1997 **
  1998 ** <dt>SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE</dt>
  1999 ** <dd> Usually, when a database in wal mode is closed or detached from a 
  2000 ** database handle, SQLite checks if this will mean that there are now no 
  2001 ** connections at all to the database. If so, it performs a checkpoint 
  2002 ** operation before closing the connection. This option may be used to
  2003 ** override this behaviour. The first parameter passed to this operation
  2004 ** is an integer - non-zero to disable checkpoints-on-close, or zero (the
  2005 ** default) to enable them. The second parameter is a pointer to an integer
  2006 ** into which is written 0 or 1 to indicate whether checkpoints-on-close
  2007 ** have been disabled - 0 if they are not disabled, 1 if they are.
  2008 ** </dd>
  2009 **
  2010 ** </dl>
  2011 */
  2012 #define SQLITE_DBCONFIG_MAINDBNAME            1000 /* const char* */
  2013 #define SQLITE_DBCONFIG_LOOKASIDE             1001 /* void* int int */
  2014 #define SQLITE_DBCONFIG_ENABLE_FKEY           1002 /* int int* */
  2015 #define SQLITE_DBCONFIG_ENABLE_TRIGGER        1003 /* int int* */
  2016 #define SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER 1004 /* int int* */
  2017 #define SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION 1005 /* int int* */
  2018 #define SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE      1006 /* int int* */
  2019 
  2020 
  2021 /*
  2022 ** CAPI3REF: Enable Or Disable Extended Result Codes
  2023 ** METHOD: sqlite3
  2024 **
  2025 ** ^The sqlite3_extended_result_codes() routine enables or disables the
  2026 ** [extended result codes] feature of SQLite. ^The extended result
  2027 ** codes are disabled by default for historical compatibility.
  2028 */
  2029 SQLITE_API int sqlite3_extended_result_codes(sqlite3*, int onoff);
  2030 
  2031 /*
  2032 ** CAPI3REF: Last Insert Rowid
  2033 ** METHOD: sqlite3
  2034 **
  2035 ** ^Each entry in most SQLite tables (except for [WITHOUT ROWID] tables)
  2036 ** has a unique 64-bit signed
  2037 ** integer key called the [ROWID | "rowid"]. ^The rowid is always available
  2038 ** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
  2039 ** names are not also used by explicitly declared columns. ^If
  2040 ** the table has a column of type [INTEGER PRIMARY KEY] then that column
  2041 ** is another alias for the rowid.
  2042 **
  2043 ** ^The sqlite3_last_insert_rowid(D) interface usually returns the [rowid] of
  2044 ** the most recent successful [INSERT] into a rowid table or [virtual table]
  2045 ** on database connection D. ^Inserts into [WITHOUT ROWID] tables are not
  2046 ** recorded. ^If no successful [INSERT]s into rowid tables have ever occurred 
  2047 ** on the database connection D, then sqlite3_last_insert_rowid(D) returns 
  2048 ** zero.
  2049 **
  2050 ** As well as being set automatically as rows are inserted into database
  2051 ** tables, the value returned by this function may be set explicitly by
  2052 ** [sqlite3_set_last_insert_rowid()]
  2053 **
  2054 ** Some virtual table implementations may INSERT rows into rowid tables as
  2055 ** part of committing a transaction (e.g. to flush data accumulated in memory
  2056 ** to disk). In this case subsequent calls to this function return the rowid
  2057 ** associated with these internal INSERT operations, which leads to 
  2058 ** unintuitive results. Virtual table implementations that do write to rowid
  2059 ** tables in this way can avoid this problem by restoring the original 
  2060 ** rowid value using [sqlite3_set_last_insert_rowid()] before returning 
  2061 ** control to the user.
  2062 **
  2063 ** ^(If an [INSERT] occurs within a trigger then this routine will 
  2064 ** return the [rowid] of the inserted row as long as the trigger is 
  2065 ** running. Once the trigger program ends, the value returned 
  2066 ** by this routine reverts to what it was before the trigger was fired.)^
  2067 **
  2068 ** ^An [INSERT] that fails due to a constraint violation is not a
  2069 ** successful [INSERT] and does not change the value returned by this
  2070 ** routine.  ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
  2071 ** and INSERT OR ABORT make no changes to the return value of this
  2072 ** routine when their insertion fails.  ^(When INSERT OR REPLACE
  2073 ** encounters a constraint violation, it does not fail.  The
  2074 ** INSERT continues to completion after deleting rows that caused
  2075 ** the constraint problem so INSERT OR REPLACE will always change
  2076 ** the return value of this interface.)^
  2077 **
  2078 ** ^For the purposes of this routine, an [INSERT] is considered to
  2079 ** be successful even if it is subsequently rolled back.
  2080 **
  2081 ** This function is accessible to SQL statements via the
  2082 ** [last_insert_rowid() SQL function].
  2083 **
  2084 ** If a separate thread performs a new [INSERT] on the same
  2085 ** database connection while the [sqlite3_last_insert_rowid()]
  2086 ** function is running and thus changes the last insert [rowid],
  2087 ** then the value returned by [sqlite3_last_insert_rowid()] is
  2088 ** unpredictable and might not equal either the old or the new
  2089 ** last insert [rowid].
  2090 */
  2091 SQLITE_API sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);
  2092 
  2093 /*
  2094 ** CAPI3REF: Set the Last Insert Rowid value.
  2095 ** METHOD: sqlite3
  2096 **
  2097 ** The sqlite3_set_last_insert_rowid(D, R) method allows the application to
  2098 ** set the value returned by calling sqlite3_last_insert_rowid(D) to R 
  2099 ** without inserting a row into the database.
  2100 */
  2101 SQLITE_API void sqlite3_set_last_insert_rowid(sqlite3*,sqlite3_int64);
  2102 
  2103 /*
  2104 ** CAPI3REF: Count The Number Of Rows Modified
  2105 ** METHOD: sqlite3
  2106 **
  2107 ** ^This function returns the number of rows modified, inserted or
  2108 ** deleted by the most recently completed INSERT, UPDATE or DELETE
  2109 ** statement on the database connection specified by the only parameter.
  2110 ** ^Executing any other type of SQL statement does not modify the value
  2111 ** returned by this function.
  2112 **
  2113 ** ^Only changes made directly by the INSERT, UPDATE or DELETE statement are
  2114 ** considered - auxiliary changes caused by [CREATE TRIGGER | triggers], 
  2115 ** [foreign key actions] or [REPLACE] constraint resolution are not counted.
  2116 ** 
  2117 ** Changes to a view that are intercepted by 
  2118 ** [INSTEAD OF trigger | INSTEAD OF triggers] are not counted. ^The value 
  2119 ** returned by sqlite3_changes() immediately after an INSERT, UPDATE or 
  2120 ** DELETE statement run on a view is always zero. Only changes made to real 
  2121 ** tables are counted.
  2122 **
  2123 ** Things are more complicated if the sqlite3_changes() function is
  2124 ** executed while a trigger program is running. This may happen if the
  2125 ** program uses the [changes() SQL function], or if some other callback
  2126 ** function invokes sqlite3_changes() directly. Essentially:
  2127 ** 
  2128 ** <ul>
  2129 **   <li> ^(Before entering a trigger program the value returned by
  2130 **        sqlite3_changes() function is saved. After the trigger program 
  2131 **        has finished, the original value is restored.)^
  2132 ** 
  2133 **   <li> ^(Within a trigger program each INSERT, UPDATE and DELETE 
  2134 **        statement sets the value returned by sqlite3_changes() 
  2135 **        upon completion as normal. Of course, this value will not include 
  2136 **        any changes performed by sub-triggers, as the sqlite3_changes() 
  2137 **        value will be saved and restored after each sub-trigger has run.)^
  2138 ** </ul>
  2139 ** 
  2140 ** ^This means that if the changes() SQL function (or similar) is used
  2141 ** by the first INSERT, UPDATE or DELETE statement within a trigger, it 
  2142 ** returns the value as set when the calling statement began executing.
  2143 ** ^If it is used by the second or subsequent such statement within a trigger 
  2144 ** program, the value returned reflects the number of rows modified by the 
  2145 ** previous INSERT, UPDATE or DELETE statement within the same trigger.
  2146 **
  2147 ** See also the [sqlite3_total_changes()] interface, the
  2148 ** [count_changes pragma], and the [changes() SQL function].
  2149 **
  2150 ** If a separate thread makes changes on the same database connection
  2151 ** while [sqlite3_changes()] is running then the value returned
  2152 ** is unpredictable and not meaningful.
  2153 */
  2154 SQLITE_API int sqlite3_changes(sqlite3*);
  2155 
  2156 /*
  2157 ** CAPI3REF: Total Number Of Rows Modified
  2158 ** METHOD: sqlite3
  2159 **
  2160 ** ^This function returns the total number of rows inserted, modified or
  2161 ** deleted by all [INSERT], [UPDATE] or [DELETE] statements completed
  2162 ** since the database connection was opened, including those executed as
  2163 ** part of trigger programs. ^Executing any other type of SQL statement
  2164 ** does not affect the value returned by sqlite3_total_changes().
  2165 ** 
  2166 ** ^Changes made as part of [foreign key actions] are included in the
  2167 ** count, but those made as part of REPLACE constraint resolution are
  2168 ** not. ^Changes to a view that are intercepted by INSTEAD OF triggers 
  2169 ** are not counted.
  2170 ** 
  2171 ** See also the [sqlite3_changes()] interface, the
  2172 ** [count_changes pragma], and the [total_changes() SQL function].
  2173 **
  2174 ** If a separate thread makes changes on the same database connection
  2175 ** while [sqlite3_total_changes()] is running then the value
  2176 ** returned is unpredictable and not meaningful.
  2177 */
  2178 SQLITE_API int sqlite3_total_changes(sqlite3*);
  2179 
  2180 /*
  2181 ** CAPI3REF: Interrupt A Long-Running Query
  2182 ** METHOD: sqlite3
  2183 **
  2184 ** ^This function causes any pending database operation to abort and
  2185 ** return at its earliest opportunity. This routine is typically
  2186 ** called in response to a user action such as pressing "Cancel"
  2187 ** or Ctrl-C where the user wants a long query operation to halt
  2188 ** immediately.
  2189 **
  2190 ** ^It is safe to call this routine from a thread different from the
  2191 ** thread that is currently running the database operation.  But it
  2192 ** is not safe to call this routine with a [database connection] that
  2193 ** is closed or might close before sqlite3_interrupt() returns.
  2194 **
  2195 ** ^If an SQL operation is very nearly finished at the time when
  2196 ** sqlite3_interrupt() is called, then it might not have an opportunity
  2197 ** to be interrupted and might continue to completion.
  2198 **
  2199 ** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
  2200 ** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
  2201 ** that is inside an explicit transaction, then the entire transaction
  2202 ** will be rolled back automatically.
  2203 **
  2204 ** ^The sqlite3_interrupt(D) call is in effect until all currently running
  2205 ** SQL statements on [database connection] D complete.  ^Any new SQL statements
  2206 ** that are started after the sqlite3_interrupt() call and before the 
  2207 ** running statements reaches zero are interrupted as if they had been
  2208 ** running prior to the sqlite3_interrupt() call.  ^New SQL statements
  2209 ** that are started after the running statement count reaches zero are
  2210 ** not effected by the sqlite3_interrupt().
  2211 ** ^A call to sqlite3_interrupt(D) that occurs when there are no running
  2212 ** SQL statements is a no-op and has no effect on SQL statements
  2213 ** that are started after the sqlite3_interrupt() call returns.
  2214 */
  2215 SQLITE_API void sqlite3_interrupt(sqlite3*);
  2216 
  2217 /*
  2218 ** CAPI3REF: Determine If An SQL Statement Is Complete
  2219 **
  2220 ** These routines are useful during command-line input to determine if the
  2221 ** currently entered text seems to form a complete SQL statement or
  2222 ** if additional input is needed before sending the text into
  2223 ** SQLite for parsing.  ^These routines return 1 if the input string
  2224 ** appears to be a complete SQL statement.  ^A statement is judged to be
  2225 ** complete if it ends with a semicolon token and is not a prefix of a
  2226 ** well-formed CREATE TRIGGER statement.  ^Semicolons that are embedded within
  2227 ** string literals or quoted identifier names or comments are not
  2228 ** independent tokens (they are part of the token in which they are
  2229 ** embedded) and thus do not count as a statement terminator.  ^Whitespace
  2230 ** and comments that follow the final semicolon are ignored.
  2231 **
  2232 ** ^These routines return 0 if the statement is incomplete.  ^If a
  2233 ** memory allocation fails, then SQLITE_NOMEM is returned.
  2234 **
  2235 ** ^These routines do not parse the SQL statements thus
  2236 ** will not detect syntactically incorrect SQL.
  2237 **
  2238 ** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior 
  2239 ** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked
  2240 ** automatically by sqlite3_complete16().  If that initialization fails,
  2241 ** then the return value from sqlite3_complete16() will be non-zero
  2242 ** regardless of whether or not the input SQL is complete.)^
  2243 **
  2244 ** The input to [sqlite3_complete()] must be a zero-terminated
  2245 ** UTF-8 string.
  2246 **
  2247 ** The input to [sqlite3_complete16()] must be a zero-terminated
  2248 ** UTF-16 string in native byte order.
  2249 */
  2250 SQLITE_API int sqlite3_complete(const char *sql);
  2251 SQLITE_API int sqlite3_complete16(const void *sql);
  2252 
  2253 /*
  2254 ** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
  2255 ** KEYWORDS: {busy-handler callback} {busy handler}
  2256 ** METHOD: sqlite3
  2257 **
  2258 ** ^The sqlite3_busy_handler(D,X,P) routine sets a callback function X
  2259 ** that might be invoked with argument P whenever
  2260 ** an attempt is made to access a database table associated with
  2261 ** [database connection] D when another thread
  2262 ** or process has the table locked.
  2263 ** The sqlite3_busy_handler() interface is used to implement
  2264 ** [sqlite3_busy_timeout()] and [PRAGMA busy_timeout].
  2265 **
  2266 ** ^If the busy callback is NULL, then [SQLITE_BUSY]
  2267 ** is returned immediately upon encountering the lock.  ^If the busy callback
  2268 ** is not NULL, then the callback might be invoked with two arguments.
  2269 **
  2270 ** ^The first argument to the busy handler is a copy of the void* pointer which
  2271 ** is the third argument to sqlite3_busy_handler().  ^The second argument to
  2272 ** the busy handler callback is the number of times that the busy handler has
  2273 ** been invoked previously for the same locking event.  ^If the
  2274 ** busy callback returns 0, then no additional attempts are made to
  2275 ** access the database and [SQLITE_BUSY] is returned
  2276 ** to the application.
  2277 ** ^If the callback returns non-zero, then another attempt
  2278 ** is made to access the database and the cycle repeats.
  2279 **
  2280 ** The presence of a busy handler does not guarantee that it will be invoked
  2281 ** when there is lock contention. ^If SQLite determines that invoking the busy
  2282 ** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
  2283 ** to the application instead of invoking the 
  2284 ** busy handler.
  2285 ** Consider a scenario where one process is holding a read lock that
  2286 ** it is trying to promote to a reserved lock and
  2287 ** a second process is holding a reserved lock that it is trying
  2288 ** to promote to an exclusive lock.  The first process cannot proceed
  2289 ** because it is blocked by the second and the second process cannot
  2290 ** proceed because it is blocked by the first.  If both processes
  2291 ** invoke the busy handlers, neither will make any progress.  Therefore,
  2292 ** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
  2293 ** will induce the first process to release its read lock and allow
  2294 ** the second process to proceed.
  2295 **
  2296 ** ^The default busy callback is NULL.
  2297 **
  2298 ** ^(There can only be a single busy handler defined for each
  2299 ** [database connection].  Setting a new busy handler clears any
  2300 ** previously set handler.)^  ^Note that calling [sqlite3_busy_timeout()]
  2301 ** or evaluating [PRAGMA busy_timeout=N] will change the
  2302 ** busy handler and thus clear any previously set busy handler.
  2303 **
  2304 ** The busy callback should not take any actions which modify the
  2305 ** database connection that invoked the busy handler.  In other words,
  2306 ** the busy handler is not reentrant.  Any such actions
  2307 ** result in undefined behavior.
  2308 ** 
  2309 ** A busy handler must not close the database connection
  2310 ** or [prepared statement] that invoked the busy handler.
  2311 */
  2312 SQLITE_API int sqlite3_busy_handler(sqlite3*,int(*)(void*,int),void*);
  2313 
  2314 /*
  2315 ** CAPI3REF: Set A Busy Timeout
  2316 ** METHOD: sqlite3
  2317 **
  2318 ** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
  2319 ** for a specified amount of time when a table is locked.  ^The handler
  2320 ** will sleep multiple times until at least "ms" milliseconds of sleeping
  2321 ** have accumulated.  ^After at least "ms" milliseconds of sleeping,
  2322 ** the handler returns 0 which causes [sqlite3_step()] to return
  2323 ** [SQLITE_BUSY].
  2324 **
  2325 ** ^Calling this routine with an argument less than or equal to zero
  2326 ** turns off all busy handlers.
  2327 **
  2328 ** ^(There can only be a single busy handler for a particular
  2329 ** [database connection] at any given moment.  If another busy handler
  2330 ** was defined  (using [sqlite3_busy_handler()]) prior to calling
  2331 ** this routine, that other busy handler is cleared.)^
  2332 **
  2333 ** See also:  [PRAGMA busy_timeout]
  2334 */
  2335 SQLITE_API int sqlite3_busy_timeout(sqlite3*, int ms);
  2336 
  2337 /*
  2338 ** CAPI3REF: Convenience Routines For Running Queries
  2339 ** METHOD: sqlite3
  2340 **
  2341 ** This is a legacy interface that is preserved for backwards compatibility.
  2342 ** Use of this interface is not recommended.
  2343 **
  2344 ** Definition: A <b>result table</b> is memory data structure created by the
  2345 ** [sqlite3_get_table()] interface.  A result table records the
  2346 ** complete query results from one or more queries.
  2347 **
  2348 ** The table conceptually has a number of rows and columns.  But
  2349 ** these numbers are not part of the result table itself.  These
  2350 ** numbers are obtained separately.  Let N be the number of rows
  2351 ** and M be the number of columns.
  2352 **
  2353 ** A result table is an array of pointers to zero-terminated UTF-8 strings.
  2354 ** There are (N+1)*M elements in the array.  The first M pointers point
  2355 ** to zero-terminated strings that  contain the names of the columns.
  2356 ** The remaining entries all point to query results.  NULL values result
  2357 ** in NULL pointers.  All other values are in their UTF-8 zero-terminated
  2358 ** string representation as returned by [sqlite3_column_text()].
  2359 **
  2360 ** A result table might consist of one or more memory allocations.
  2361 ** It is not safe to pass a result table directly to [sqlite3_free()].
  2362 ** A result table should be deallocated using [sqlite3_free_table()].
  2363 **
  2364 ** ^(As an example of the result table format, suppose a query result
  2365 ** is as follows:
  2366 **
  2367 ** <blockquote><pre>
  2368 **        Name        | Age
  2369 **        -----------------------
  2370 **        Alice       | 43
  2371 **        Bob         | 28
  2372 **        Cindy       | 21
  2373 ** </pre></blockquote>
  2374 **
  2375 ** There are two column (M==2) and three rows (N==3).  Thus the
  2376 ** result table has 8 entries.  Suppose the result table is stored
  2377 ** in an array names azResult.  Then azResult holds this content:
  2378 **
  2379 ** <blockquote><pre>
  2380 **        azResult&#91;0] = "Name";
  2381 **        azResult&#91;1] = "Age";
  2382 **        azResult&#91;2] = "Alice";
  2383 **        azResult&#91;3] = "43";
  2384 **        azResult&#91;4] = "Bob";
  2385 **        azResult&#91;5] = "28";
  2386 **        azResult&#91;6] = "Cindy";
  2387 **        azResult&#91;7] = "21";
  2388 ** </pre></blockquote>)^
  2389 **
  2390 ** ^The sqlite3_get_table() function evaluates one or more
  2391 ** semicolon-separated SQL statements in the zero-terminated UTF-8
  2392 ** string of its 2nd parameter and returns a result table to the
  2393 ** pointer given in its 3rd parameter.
  2394 **
  2395 ** After the application has finished with the result from sqlite3_get_table(),
  2396 ** it must pass the result table pointer to sqlite3_free_table() in order to
  2397 ** release the memory that was malloced.  Because of the way the
  2398 ** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
  2399 ** function must not try to call [sqlite3_free()] directly.  Only
  2400 ** [sqlite3_free_table()] is able to release the memory properly and safely.
  2401 **
  2402 ** The sqlite3_get_table() interface is implemented as a wrapper around
  2403 ** [sqlite3_exec()].  The sqlite3_get_table() routine does not have access
  2404 ** to any internal data structures of SQLite.  It uses only the public
  2405 ** interface defined here.  As a consequence, errors that occur in the
  2406 ** wrapper layer outside of the internal [sqlite3_exec()] call are not
  2407 ** reflected in subsequent calls to [sqlite3_errcode()] or
  2408 ** [sqlite3_errmsg()].
  2409 */
  2410 SQLITE_API int sqlite3_get_table(
  2411   sqlite3 *db,          /* An open database */
  2412   const char *zSql,     /* SQL to be evaluated */
  2413   char ***pazResult,    /* Results of the query */
  2414   int *pnRow,           /* Number of result rows written here */
  2415   int *pnColumn,        /* Number of result columns written here */
  2416   char **pzErrmsg       /* Error msg written here */
  2417 );
  2418 SQLITE_API void sqlite3_free_table(char **result);
  2419 
  2420 /*
  2421 ** CAPI3REF: Formatted String Printing Functions
  2422 **
  2423 ** These routines are work-alikes of the "printf()" family of functions
  2424 ** from the standard C library.
  2425 ** These routines understand most of the common K&R formatting options,
  2426 ** plus some additional non-standard formats, detailed below.
  2427 ** Note that some of the more obscure formatting options from recent
  2428 ** C-library standards are omitted from this implementation.
  2429 **
  2430 ** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
  2431 ** results into memory obtained from [sqlite3_malloc()].
  2432 ** The strings returned by these two routines should be
  2433 ** released by [sqlite3_free()].  ^Both routines return a
  2434 ** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
  2435 ** memory to hold the resulting string.
  2436 **
  2437 ** ^(The sqlite3_snprintf() routine is similar to "snprintf()" from
  2438 ** the standard C library.  The result is written into the
  2439 ** buffer supplied as the second parameter whose size is given by
  2440 ** the first parameter. Note that the order of the
  2441 ** first two parameters is reversed from snprintf().)^  This is an
  2442 ** historical accident that cannot be fixed without breaking
  2443 ** backwards compatibility.  ^(Note also that sqlite3_snprintf()
  2444 ** returns a pointer to its buffer instead of the number of
  2445 ** characters actually written into the buffer.)^  We admit that
  2446 ** the number of characters written would be a more useful return
  2447 ** value but we cannot change the implementation of sqlite3_snprintf()
  2448 ** now without breaking compatibility.
  2449 **
  2450 ** ^As long as the buffer size is greater than zero, sqlite3_snprintf()
  2451 ** guarantees that the buffer is always zero-terminated.  ^The first
  2452 ** parameter "n" is the total size of the buffer, including space for
  2453 ** the zero terminator.  So the longest string that can be completely
  2454 ** written will be n-1 characters.
  2455 **
  2456 ** ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf().
  2457 **
  2458 ** These routines all implement some additional formatting
  2459 ** options that are useful for constructing SQL statements.
  2460 ** All of the usual printf() formatting options apply.  In addition, there
  2461 ** is are "%q", "%Q", "%w" and "%z" options.
  2462 **
  2463 ** ^(The %q option works like %s in that it substitutes a nul-terminated
  2464 ** string from the argument list.  But %q also doubles every '\'' character.
  2465 ** %q is designed for use inside a string literal.)^  By doubling each '\''
  2466 ** character it escapes that character and allows it to be inserted into
  2467 ** the string.
  2468 **
  2469 ** For example, assume the string variable zText contains text as follows:
  2470 **
  2471 ** <blockquote><pre>
  2472 **  char *zText = "It's a happy day!";
  2473 ** </pre></blockquote>
  2474 **
  2475 ** One can use this text in an SQL statement as follows:
  2476 **
  2477 ** <blockquote><pre>
  2478 **  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);
  2479 **  sqlite3_exec(db, zSQL, 0, 0, 0);
  2480 **  sqlite3_free(zSQL);
  2481 ** </pre></blockquote>
  2482 **
  2483 ** Because the %q format string is used, the '\'' character in zText
  2484 ** is escaped and the SQL generated is as follows:
  2485 **
  2486 ** <blockquote><pre>
  2487 **  INSERT INTO table1 VALUES('It''s a happy day!')
  2488 ** </pre></blockquote>
  2489 **
  2490 ** This is correct.  Had we used %s instead of %q, the generated SQL
  2491 ** would have looked like this:
  2492 **
  2493 ** <blockquote><pre>
  2494 **  INSERT INTO table1 VALUES('It's a happy day!');
  2495 ** </pre></blockquote>
  2496 **
  2497 ** This second example is an SQL syntax error.  As a general rule you should
  2498 ** always use %q instead of %s when inserting text into a string literal.
  2499 **
  2500 ** ^(The %Q option works like %q except it also adds single quotes around
  2501 ** the outside of the total string.  Additionally, if the parameter in the
  2502 ** argument list is a NULL pointer, %Q substitutes the text "NULL" (without
  2503 ** single quotes).)^  So, for example, one could say:
  2504 **
  2505 ** <blockquote><pre>
  2506 **  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);
  2507 **  sqlite3_exec(db, zSQL, 0, 0, 0);
  2508 **  sqlite3_free(zSQL);
  2509 ** </pre></blockquote>
  2510 **
  2511 ** The code above will render a correct SQL statement in the zSQL
  2512 ** variable even if the zText variable is a NULL pointer.
  2513 **
  2514 ** ^(The "%w" formatting option is like "%q" except that it expects to
  2515 ** be contained within double-quotes instead of single quotes, and it
  2516 ** escapes the double-quote character instead of the single-quote
  2517 ** character.)^  The "%w" formatting option is intended for safely inserting
  2518 ** table and column names into a constructed SQL statement.
  2519 **
  2520 ** ^(The "%z" formatting option works like "%s" but with the
  2521 ** addition that after the string has been read and copied into
  2522 ** the result, [sqlite3_free()] is called on the input string.)^
  2523 */
  2524 SQLITE_API char *sqlite3_mprintf(const char*,...);
  2525 SQLITE_API char *sqlite3_vmprintf(const char*, va_list);
  2526 SQLITE_API char *sqlite3_snprintf(int,char*,const char*, ...);
  2527 SQLITE_API char *sqlite3_vsnprintf(int,char*,const char*, va_list);
  2528 
  2529 /*
  2530 ** CAPI3REF: Memory Allocation Subsystem
  2531 **
  2532 ** The SQLite core uses these three routines for all of its own
  2533 ** internal memory allocation needs. "Core" in the previous sentence
  2534 ** does not include operating-system specific VFS implementation.  The
  2535 ** Windows VFS uses native malloc() and free() for some operations.
  2536 **
  2537 ** ^The sqlite3_malloc() routine returns a pointer to a block
  2538 ** of memory at least N bytes in length, where N is the parameter.
  2539 ** ^If sqlite3_malloc() is unable to obtain sufficient free
  2540 ** memory, it returns a NULL pointer.  ^If the parameter N to
  2541 ** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
  2542 ** a NULL pointer.
  2543 **
  2544 ** ^The sqlite3_malloc64(N) routine works just like
  2545 ** sqlite3_malloc(N) except that N is an unsigned 64-bit integer instead
  2546 ** of a signed 32-bit integer.
  2547 **
  2548 ** ^Calling sqlite3_free() with a pointer previously returned
  2549 ** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
  2550 ** that it might be reused.  ^The sqlite3_free() routine is
  2551 ** a no-op if is called with a NULL pointer.  Passing a NULL pointer
  2552 ** to sqlite3_free() is harmless.  After being freed, memory
  2553 ** should neither be read nor written.  Even reading previously freed
  2554 ** memory might result in a segmentation fault or other severe error.
  2555 ** Memory corruption, a segmentation fault, or other severe error
  2556 ** might result if sqlite3_free() is called with a non-NULL pointer that
  2557 ** was not obtained from sqlite3_malloc() or sqlite3_realloc().
  2558 **
  2559 ** ^The sqlite3_realloc(X,N) interface attempts to resize a
  2560 ** prior memory allocation X to be at least N bytes.
  2561 ** ^If the X parameter to sqlite3_realloc(X,N)
  2562 ** is a NULL pointer then its behavior is identical to calling
  2563 ** sqlite3_malloc(N).
  2564 ** ^If the N parameter to sqlite3_realloc(X,N) is zero or
  2565 ** negative then the behavior is exactly the same as calling
  2566 ** sqlite3_free(X).
  2567 ** ^sqlite3_realloc(X,N) returns a pointer to a memory allocation
  2568 ** of at least N bytes in size or NULL if insufficient memory is available.
  2569 ** ^If M is the size of the prior allocation, then min(N,M) bytes
  2570 ** of the prior allocation are copied into the beginning of buffer returned
  2571 ** by sqlite3_realloc(X,N) and the prior allocation is freed.
  2572 ** ^If sqlite3_realloc(X,N) returns NULL and N is positive, then the
  2573 ** prior allocation is not freed.
  2574 **
  2575 ** ^The sqlite3_realloc64(X,N) interfaces works the same as
  2576 ** sqlite3_realloc(X,N) except that N is a 64-bit unsigned integer instead
  2577 ** of a 32-bit signed integer.
  2578 **
  2579 ** ^If X is a memory allocation previously obtained from sqlite3_malloc(),
  2580 ** sqlite3_malloc64(), sqlite3_realloc(), or sqlite3_realloc64(), then
  2581 ** sqlite3_msize(X) returns the size of that memory allocation in bytes.
  2582 ** ^The value returned by sqlite3_msize(X) might be larger than the number
  2583 ** of bytes requested when X was allocated.  ^If X is a NULL pointer then
  2584 ** sqlite3_msize(X) returns zero.  If X points to something that is not
  2585 ** the beginning of memory allocation, or if it points to a formerly
  2586 ** valid memory allocation that has now been freed, then the behavior
  2587 ** of sqlite3_msize(X) is undefined and possibly harmful.
  2588 **
  2589 ** ^The memory returned by sqlite3_malloc(), sqlite3_realloc(),
  2590 ** sqlite3_malloc64(), and sqlite3_realloc64()
  2591 ** is always aligned to at least an 8 byte boundary, or to a
  2592 ** 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time
  2593 ** option is used.
  2594 **
  2595 ** In SQLite version 3.5.0 and 3.5.1, it was possible to define
  2596 ** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
  2597 ** implementation of these routines to be omitted.  That capability
  2598 ** is no longer provided.  Only built-in memory allocators can be used.
  2599 **
  2600 ** Prior to SQLite version 3.7.10, the Windows OS interface layer called
  2601 ** the system malloc() and free() directly when converting
  2602 ** filenames between the UTF-8 encoding used by SQLite
  2603 ** and whatever filename encoding is used by the particular Windows
  2604 ** installation.  Memory allocation errors were detected, but
  2605 ** they were reported back as [SQLITE_CANTOPEN] or
  2606 ** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
  2607 **
  2608 ** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
  2609 ** must be either NULL or else pointers obtained from a prior
  2610 ** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
  2611 ** not yet been released.
  2612 **
  2613 ** The application must not read or write any part of
  2614 ** a block of memory after it has been released using
  2615 ** [sqlite3_free()] or [sqlite3_realloc()].
  2616 */
  2617 SQLITE_API void *sqlite3_malloc(int);
  2618 SQLITE_API void *sqlite3_malloc64(sqlite3_uint64);
  2619 SQLITE_API void *sqlite3_realloc(void*, int);
  2620 SQLITE_API void *sqlite3_realloc64(void*, sqlite3_uint64);
  2621 SQLITE_API void sqlite3_free(void*);
  2622 SQLITE_API sqlite3_uint64 sqlite3_msize(void*);
  2623 
  2624 /*
  2625 ** CAPI3REF: Memory Allocator Statistics
  2626 **
  2627 ** SQLite provides these two interfaces for reporting on the status
  2628 ** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
  2629 ** routines, which form the built-in memory allocation subsystem.
  2630 **
  2631 ** ^The [sqlite3_memory_used()] routine returns the number of bytes
  2632 ** of memory currently outstanding (malloced but not freed).
  2633 ** ^The [sqlite3_memory_highwater()] routine returns the maximum
  2634 ** value of [sqlite3_memory_used()] since the high-water mark
  2635 ** was last reset.  ^The values returned by [sqlite3_memory_used()] and
  2636 ** [sqlite3_memory_highwater()] include any overhead
  2637 ** added by SQLite in its implementation of [sqlite3_malloc()],
  2638 ** but not overhead added by the any underlying system library
  2639 ** routines that [sqlite3_malloc()] may call.
  2640 **
  2641 ** ^The memory high-water mark is reset to the current value of
  2642 ** [sqlite3_memory_used()] if and only if the parameter to
  2643 ** [sqlite3_memory_highwater()] is true.  ^The value returned
  2644 ** by [sqlite3_memory_highwater(1)] is the high-water mark
  2645 ** prior to the reset.
  2646 */
  2647 SQLITE_API sqlite3_int64 sqlite3_memory_used(void);
  2648 SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag);
  2649 
  2650 /*
  2651 ** CAPI3REF: Pseudo-Random Number Generator
  2652 **
  2653 ** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
  2654 ** select random [ROWID | ROWIDs] when inserting new records into a table that
  2655 ** already uses the largest possible [ROWID].  The PRNG is also used for
  2656 ** the build-in random() and randomblob() SQL functions.  This interface allows
  2657 ** applications to access the same PRNG for other purposes.
  2658 **
  2659 ** ^A call to this routine stores N bytes of randomness into buffer P.
  2660 ** ^The P parameter can be a NULL pointer.
  2661 **
  2662 ** ^If this routine has not been previously called or if the previous
  2663 ** call had N less than one or a NULL pointer for P, then the PRNG is
  2664 ** seeded using randomness obtained from the xRandomness method of
  2665 ** the default [sqlite3_vfs] object.
  2666 ** ^If the previous call to this routine had an N of 1 or more and a
  2667 ** non-NULL P then the pseudo-randomness is generated
  2668 ** internally and without recourse to the [sqlite3_vfs] xRandomness
  2669 ** method.
  2670 */
  2671 SQLITE_API void sqlite3_randomness(int N, void *P);
  2672 
  2673 /*
  2674 ** CAPI3REF: Compile-Time Authorization Callbacks
  2675 ** METHOD: sqlite3
  2676 ** KEYWORDS: {authorizer callback}
  2677 **
  2678 ** ^This routine registers an authorizer callback with a particular
  2679 ** [database connection], supplied in the first argument.
  2680 ** ^The authorizer callback is invoked as SQL statements are being compiled
  2681 ** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
  2682 ** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()].  ^At various
  2683 ** points during the compilation process, as logic is being created
  2684 ** to perform various actions, the authorizer callback is invoked to
  2685 ** see if those actions are allowed.  ^The authorizer callback should
  2686 ** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
  2687 ** specific action but allow the SQL statement to continue to be
  2688 ** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
  2689 ** rejected with an error.  ^If the authorizer callback returns
  2690 ** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
  2691 ** then the [sqlite3_prepare_v2()] or equivalent call that triggered
  2692 ** the authorizer will fail with an error message.
  2693 **
  2694 ** When the callback returns [SQLITE_OK], that means the operation
  2695 ** requested is ok.  ^When the callback returns [SQLITE_DENY], the
  2696 ** [sqlite3_prepare_v2()] or equivalent call that triggered the
  2697 ** authorizer will fail with an error message explaining that
  2698 ** access is denied. 
  2699 **
  2700 ** ^The first parameter to the authorizer callback is a copy of the third
  2701 ** parameter to the sqlite3_set_authorizer() interface. ^The second parameter
  2702 ** to the callback is an integer [SQLITE_COPY | action code] that specifies
  2703 ** the particular action to be authorized. ^The third through sixth parameters
  2704 ** to the callback are either NULL pointers or zero-terminated strings
  2705 ** that contain additional details about the action to be authorized.
  2706 ** Applications must always be prepared to encounter a NULL pointer in any
  2707 ** of the third through the sixth parameters of the authorization callback.
  2708 **
  2709 ** ^If the action code is [SQLITE_READ]
  2710 ** and the callback returns [SQLITE_IGNORE] then the
  2711 ** [prepared statement] statement is constructed to substitute
  2712 ** a NULL value in place of the table column that would have
  2713 ** been read if [SQLITE_OK] had been returned.  The [SQLITE_IGNORE]
  2714 ** return can be used to deny an untrusted user access to individual
  2715 ** columns of a table.
  2716 ** ^When a table is referenced by a [SELECT] but no column values are
  2717 ** extracted from that table (for example in a query like
  2718 ** "SELECT count(*) FROM tab") then the [SQLITE_READ] authorizer callback
  2719 ** is invoked once for that table with a column name that is an empty string.
  2720 ** ^If the action code is [SQLITE_DELETE] and the callback returns
  2721 ** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the
  2722 ** [truncate optimization] is disabled and all rows are deleted individually.
  2723 **
  2724 ** An authorizer is used when [sqlite3_prepare | preparing]
  2725 ** SQL statements from an untrusted source, to ensure that the SQL statements
  2726 ** do not try to access data they are not allowed to see, or that they do not
  2727 ** try to execute malicious statements that damage the database.  For
  2728 ** example, an application may allow a user to enter arbitrary
  2729 ** SQL queries for evaluation by a database.  But the application does
  2730 ** not want the user to be able to make arbitrary changes to the
  2731 ** database.  An authorizer could then be put in place while the
  2732 ** user-entered SQL is being [sqlite3_prepare | prepared] that
  2733 ** disallows everything except [SELECT] statements.
  2734 **
  2735 ** Applications that need to process SQL from untrusted sources
  2736 ** might also consider lowering resource limits using [sqlite3_limit()]
  2737 ** and limiting database size using the [max_page_count] [PRAGMA]
  2738 ** in addition to using an authorizer.
  2739 **
  2740 ** ^(Only a single authorizer can be in place on a database connection
  2741 ** at a time.  Each call to sqlite3_set_authorizer overrides the
  2742 ** previous call.)^  ^Disable the authorizer by installing a NULL callback.
  2743 ** The authorizer is disabled by default.
  2744 **
  2745 ** The authorizer callback must not do anything that will modify
  2746 ** the database connection that invoked the authorizer callback.
  2747 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  2748 ** database connections for the meaning of "modify" in this paragraph.
  2749 **
  2750 ** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the
  2751 ** statement might be re-prepared during [sqlite3_step()] due to a 
  2752 ** schema change.  Hence, the application should ensure that the
  2753 ** correct authorizer callback remains in place during the [sqlite3_step()].
  2754 **
  2755 ** ^Note that the authorizer callback is invoked only during
  2756 ** [sqlite3_prepare()] or its variants.  Authorization is not
  2757 ** performed during statement evaluation in [sqlite3_step()], unless
  2758 ** as stated in the previous paragraph, sqlite3_step() invokes
  2759 ** sqlite3_prepare_v2() to reprepare a statement after a schema change.
  2760 */
  2761 SQLITE_API int sqlite3_set_authorizer(
  2762   sqlite3*,
  2763   int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
  2764   void *pUserData
  2765 );
  2766 
  2767 /*
  2768 ** CAPI3REF: Authorizer Return Codes
  2769 **
  2770 ** The [sqlite3_set_authorizer | authorizer callback function] must
  2771 ** return either [SQLITE_OK] or one of these two constants in order
  2772 ** to signal SQLite whether or not the action is permitted.  See the
  2773 ** [sqlite3_set_authorizer | authorizer documentation] for additional
  2774 ** information.
  2775 **
  2776 ** Note that SQLITE_IGNORE is also used as a [conflict resolution mode]
  2777 ** returned from the [sqlite3_vtab_on_conflict()] interface.
  2778 */
  2779 #define SQLITE_DENY   1   /* Abort the SQL statement with an error */
  2780 #define SQLITE_IGNORE 2   /* Don't allow access, but don't generate an error */
  2781 
  2782 /*
  2783 ** CAPI3REF: Authorizer Action Codes
  2784 **
  2785 ** The [sqlite3_set_authorizer()] interface registers a callback function
  2786 ** that is invoked to authorize certain SQL statement actions.  The
  2787 ** second parameter to the callback is an integer code that specifies
  2788 ** what action is being authorized.  These are the integer action codes that
  2789 ** the authorizer callback may be passed.
  2790 **
  2791 ** These action code values signify what kind of operation is to be
  2792 ** authorized.  The 3rd and 4th parameters to the authorization
  2793 ** callback function will be parameters or NULL depending on which of these
  2794 ** codes is used as the second parameter.  ^(The 5th parameter to the
  2795 ** authorizer callback is the name of the database ("main", "temp",
  2796 ** etc.) if applicable.)^  ^The 6th parameter to the authorizer callback
  2797 ** is the name of the inner-most trigger or view that is responsible for
  2798 ** the access attempt or NULL if this access attempt is directly from
  2799 ** top-level SQL code.
  2800 */
  2801 /******************************************* 3rd ************ 4th ***********/
  2802 #define SQLITE_CREATE_INDEX          1   /* Index Name      Table Name      */
  2803 #define SQLITE_CREATE_TABLE          2   /* Table Name      NULL            */
  2804 #define SQLITE_CREATE_TEMP_INDEX     3   /* Index Name      Table Name      */
  2805 #define SQLITE_CREATE_TEMP_TABLE     4   /* Table Name      NULL            */
  2806 #define SQLITE_CREATE_TEMP_TRIGGER   5   /* Trigger Name    Table Name      */
  2807 #define SQLITE_CREATE_TEMP_VIEW      6   /* View Name       NULL            */
  2808 #define SQLITE_CREATE_TRIGGER        7   /* Trigger Name    Table Name      */
  2809 #define SQLITE_CREATE_VIEW           8   /* View Name       NULL            */
  2810 #define SQLITE_DELETE                9   /* Table Name      NULL            */
  2811 #define SQLITE_DROP_INDEX           10   /* Index Name      Table Name      */
  2812 #define SQLITE_DROP_TABLE           11   /* Table Name      NULL            */
  2813 #define SQLITE_DROP_TEMP_INDEX      12   /* Index Name      Table Name      */
  2814 #define SQLITE_DROP_TEMP_TABLE      13   /* Table Name      NULL            */
  2815 #define SQLITE_DROP_TEMP_TRIGGER    14   /* Trigger Name    Table Name      */
  2816 #define SQLITE_DROP_TEMP_VIEW       15   /* View Name       NULL            */
  2817 #define SQLITE_DROP_TRIGGER         16   /* Trigger Name    Table Name      */
  2818 #define SQLITE_DROP_VIEW            17   /* View Name       NULL            */
  2819 #define SQLITE_INSERT               18   /* Table Name      NULL            */
  2820 #define SQLITE_PRAGMA               19   /* Pragma Name     1st arg or NULL */
  2821 #define SQLITE_READ                 20   /* Table Name      Column Name     */
  2822 #define SQLITE_SELECT               21   /* NULL            NULL            */
  2823 #define SQLITE_TRANSACTION          22   /* Operation       NULL            */
  2824 #define SQLITE_UPDATE               23   /* Table Name      Column Name     */
  2825 #define SQLITE_ATTACH               24   /* Filename        NULL            */
  2826 #define SQLITE_DETACH               25   /* Database Name   NULL            */
  2827 #define SQLITE_ALTER_TABLE          26   /* Database Name   Table Name      */
  2828 #define SQLITE_REINDEX              27   /* Index Name      NULL            */
  2829 #define SQLITE_ANALYZE              28   /* Table Name      NULL            */
  2830 #define SQLITE_CREATE_VTABLE        29   /* Table Name      Module Name     */
  2831 #define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
  2832 #define SQLITE_FUNCTION             31   /* NULL            Function Name   */
  2833 #define SQLITE_SAVEPOINT            32   /* Operation       Savepoint Name  */
  2834 #define SQLITE_COPY                  0   /* No longer used */
  2835 #define SQLITE_RECURSIVE            33   /* NULL            NULL            */
  2836 
  2837 /*
  2838 ** CAPI3REF: Tracing And Profiling Functions
  2839 ** METHOD: sqlite3
  2840 **
  2841 ** These routines are deprecated. Use the [sqlite3_trace_v2()] interface
  2842 ** instead of the routines described here.
  2843 **
  2844 ** These routines register callback functions that can be used for
  2845 ** tracing and profiling the execution of SQL statements.
  2846 **
  2847 ** ^The callback function registered by sqlite3_trace() is invoked at
  2848 ** various times when an SQL statement is being run by [sqlite3_step()].
  2849 ** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
  2850 ** SQL statement text as the statement first begins executing.
  2851 ** ^(Additional sqlite3_trace() callbacks might occur
  2852 ** as each triggered subprogram is entered.  The callbacks for triggers
  2853 ** contain a UTF-8 SQL comment that identifies the trigger.)^
  2854 **
  2855 ** The [SQLITE_TRACE_SIZE_LIMIT] compile-time option can be used to limit
  2856 ** the length of [bound parameter] expansion in the output of sqlite3_trace().
  2857 **
  2858 ** ^The callback function registered by sqlite3_profile() is invoked
  2859 ** as each SQL statement finishes.  ^The profile callback contains
  2860 ** the original statement text and an estimate of wall-clock time
  2861 ** of how long that statement took to run.  ^The profile callback
  2862 ** time is in units of nanoseconds, however the current implementation
  2863 ** is only capable of millisecond resolution so the six least significant
  2864 ** digits in the time are meaningless.  Future versions of SQLite
  2865 ** might provide greater resolution on the profiler callback.  The
  2866 ** sqlite3_profile() function is considered experimental and is
  2867 ** subject to change in future versions of SQLite.
  2868 */
  2869 SQLITE_API SQLITE_DEPRECATED void *sqlite3_trace(sqlite3*,
  2870    void(*xTrace)(void*,const char*), void*);
  2871 SQLITE_API SQLITE_DEPRECATED void *sqlite3_profile(sqlite3*,
  2872    void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
  2873 
  2874 /*
  2875 ** CAPI3REF: SQL Trace Event Codes
  2876 ** KEYWORDS: SQLITE_TRACE
  2877 **
  2878 ** These constants identify classes of events that can be monitored
  2879 ** using the [sqlite3_trace_v2()] tracing logic.  The third argument
  2880 ** to [sqlite3_trace_v2()] is an OR-ed combination of one or more of
  2881 ** the following constants.  ^The first argument to the trace callback
  2882 ** is one of the following constants.
  2883 **
  2884 ** New tracing constants may be added in future releases.
  2885 **
  2886 ** ^A trace callback has four arguments: xCallback(T,C,P,X).
  2887 ** ^The T argument is one of the integer type codes above.
  2888 ** ^The C argument is a copy of the context pointer passed in as the
  2889 ** fourth argument to [sqlite3_trace_v2()].
  2890 ** The P and X arguments are pointers whose meanings depend on T.
  2891 **
  2892 ** <dl>
  2893 ** [[SQLITE_TRACE_STMT]] <dt>SQLITE_TRACE_STMT</dt>
  2894 ** <dd>^An SQLITE_TRACE_STMT callback is invoked when a prepared statement
  2895 ** first begins running and possibly at other times during the
  2896 ** execution of the prepared statement, such as at the start of each
  2897 ** trigger subprogram. ^The P argument is a pointer to the
  2898 ** [prepared statement]. ^The X argument is a pointer to a string which
  2899 ** is the unexpanded SQL text of the prepared statement or an SQL comment 
  2900 ** that indicates the invocation of a trigger.  ^The callback can compute
  2901 ** the same text that would have been returned by the legacy [sqlite3_trace()]
  2902 ** interface by using the X argument when X begins with "--" and invoking
  2903 ** [sqlite3_expanded_sql(P)] otherwise.
  2904 **
  2905 ** [[SQLITE_TRACE_PROFILE]] <dt>SQLITE_TRACE_PROFILE</dt>
  2906 ** <dd>^An SQLITE_TRACE_PROFILE callback provides approximately the same
  2907 ** information as is provided by the [sqlite3_profile()] callback.
  2908 ** ^The P argument is a pointer to the [prepared statement] and the
  2909 ** X argument points to a 64-bit integer which is the estimated of
  2910 ** the number of nanosecond that the prepared statement took to run.
  2911 ** ^The SQLITE_TRACE_PROFILE callback is invoked when the statement finishes.
  2912 **
  2913 ** [[SQLITE_TRACE_ROW]] <dt>SQLITE_TRACE_ROW</dt>
  2914 ** <dd>^An SQLITE_TRACE_ROW callback is invoked whenever a prepared
  2915 ** statement generates a single row of result.  
  2916 ** ^The P argument is a pointer to the [prepared statement] and the
  2917 ** X argument is unused.
  2918 **
  2919 ** [[SQLITE_TRACE_CLOSE]] <dt>SQLITE_TRACE_CLOSE</dt>
  2920 ** <dd>^An SQLITE_TRACE_CLOSE callback is invoked when a database
  2921 ** connection closes.
  2922 ** ^The P argument is a pointer to the [database connection] object
  2923 ** and the X argument is unused.
  2924 ** </dl>
  2925 */
  2926 #define SQLITE_TRACE_STMT       0x01
  2927 #define SQLITE_TRACE_PROFILE    0x02
  2928 #define SQLITE_TRACE_ROW        0x04
  2929 #define SQLITE_TRACE_CLOSE      0x08
  2930 
  2931 /*
  2932 ** CAPI3REF: SQL Trace Hook
  2933 ** METHOD: sqlite3
  2934 **
  2935 ** ^The sqlite3_trace_v2(D,M,X,P) interface registers a trace callback
  2936 ** function X against [database connection] D, using property mask M
  2937 ** and context pointer P.  ^If the X callback is
  2938 ** NULL or if the M mask is zero, then tracing is disabled.  The
  2939 ** M argument should be the bitwise OR-ed combination of
  2940 ** zero or more [SQLITE_TRACE] constants.
  2941 **
  2942 ** ^Each call to either sqlite3_trace() or sqlite3_trace_v2() overrides 
  2943 ** (cancels) any prior calls to sqlite3_trace() or sqlite3_trace_v2().
  2944 **
  2945 ** ^The X callback is invoked whenever any of the events identified by 
  2946 ** mask M occur.  ^The integer return value from the callback is currently
  2947 ** ignored, though this may change in future releases.  Callback
  2948 ** implementations should return zero to ensure future compatibility.
  2949 **
  2950 ** ^A trace callback is invoked with four arguments: callback(T,C,P,X).
  2951 ** ^The T argument is one of the [SQLITE_TRACE]
  2952 ** constants to indicate why the callback was invoked.
  2953 ** ^The C argument is a copy of the context pointer.
  2954 ** The P and X arguments are pointers whose meanings depend on T.
  2955 **
  2956 ** The sqlite3_trace_v2() interface is intended to replace the legacy
  2957 ** interfaces [sqlite3_trace()] and [sqlite3_profile()], both of which
  2958 ** are deprecated.
  2959 */
  2960 SQLITE_API int sqlite3_trace_v2(
  2961   sqlite3*,
  2962   unsigned uMask,
  2963   int(*xCallback)(unsigned,void*,void*,void*),
  2964   void *pCtx
  2965 );
  2966 
  2967 /*
  2968 ** CAPI3REF: Query Progress Callbacks
  2969 ** METHOD: sqlite3
  2970 **
  2971 ** ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback
  2972 ** function X to be invoked periodically during long running calls to
  2973 ** [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for
  2974 ** database connection D.  An example use for this
  2975 ** interface is to keep a GUI updated during a large query.
  2976 **
  2977 ** ^The parameter P is passed through as the only parameter to the 
  2978 ** callback function X.  ^The parameter N is the approximate number of 
  2979 ** [virtual machine instructions] that are evaluated between successive
  2980 ** invocations of the callback X.  ^If N is less than one then the progress
  2981 ** handler is disabled.
  2982 **
  2983 ** ^Only a single progress handler may be defined at one time per
  2984 ** [database connection]; setting a new progress handler cancels the
  2985 ** old one.  ^Setting parameter X to NULL disables the progress handler.
  2986 ** ^The progress handler is also disabled by setting N to a value less
  2987 ** than 1.
  2988 **
  2989 ** ^If the progress callback returns non-zero, the operation is
  2990 ** interrupted.  This feature can be used to implement a
  2991 ** "Cancel" button on a GUI progress dialog box.
  2992 **
  2993 ** The progress handler callback must not do anything that will modify
  2994 ** the database connection that invoked the progress handler.
  2995 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  2996 ** database connections for the meaning of "modify" in this paragraph.
  2997 **
  2998 */
  2999 SQLITE_API void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
  3000 
  3001 /*
  3002 ** CAPI3REF: Opening A New Database Connection
  3003 ** CONSTRUCTOR: sqlite3
  3004 **
  3005 ** ^These routines open an SQLite database file as specified by the 
  3006 ** filename argument. ^The filename argument is interpreted as UTF-8 for
  3007 ** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
  3008 ** order for sqlite3_open16(). ^(A [database connection] handle is usually
  3009 ** returned in *ppDb, even if an error occurs.  The only exception is that
  3010 ** if SQLite is unable to allocate memory to hold the [sqlite3] object,
  3011 ** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
  3012 ** object.)^ ^(If the database is opened (and/or created) successfully, then
  3013 ** [SQLITE_OK] is returned.  Otherwise an [error code] is returned.)^ ^The
  3014 ** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
  3015 ** an English language description of the error following a failure of any
  3016 ** of the sqlite3_open() routines.
  3017 **
  3018 ** ^The default encoding will be UTF-8 for databases created using
  3019 ** sqlite3_open() or sqlite3_open_v2().  ^The default encoding for databases
  3020 ** created using sqlite3_open16() will be UTF-16 in the native byte order.
  3021 **
  3022 ** Whether or not an error occurs when it is opened, resources
  3023 ** associated with the [database connection] handle should be released by
  3024 ** passing it to [sqlite3_close()] when it is no longer required.
  3025 **
  3026 ** The sqlite3_open_v2() interface works like sqlite3_open()
  3027 ** except that it accepts two additional parameters for additional control
  3028 ** over the new database connection.  ^(The flags parameter to
  3029 ** sqlite3_open_v2() can take one of
  3030 ** the following three values, optionally combined with the 
  3031 ** [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE],
  3032 ** [SQLITE_OPEN_PRIVATECACHE], and/or [SQLITE_OPEN_URI] flags:)^
  3033 **
  3034 ** <dl>
  3035 ** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
  3036 ** <dd>The database is opened in read-only mode.  If the database does not
  3037 ** already exist, an error is returned.</dd>)^
  3038 **
  3039 ** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
  3040 ** <dd>The database is opened for reading and writing if possible, or reading
  3041 ** only if the file is write protected by the operating system.  In either
  3042 ** case the database must already exist, otherwise an error is returned.</dd>)^
  3043 **
  3044 ** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
  3045 ** <dd>The database is opened for reading and writing, and is created if
  3046 ** it does not already exist. This is the behavior that is always used for
  3047 ** sqlite3_open() and sqlite3_open16().</dd>)^
  3048 ** </dl>
  3049 **
  3050 ** If the 3rd parameter to sqlite3_open_v2() is not one of the
  3051 ** combinations shown above optionally combined with other
  3052 ** [SQLITE_OPEN_READONLY | SQLITE_OPEN_* bits]
  3053 ** then the behavior is undefined.
  3054 **
  3055 ** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
  3056 ** opens in the multi-thread [threading mode] as long as the single-thread
  3057 ** mode has not been set at compile-time or start-time.  ^If the
  3058 ** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
  3059 ** in the serialized [threading mode] unless single-thread was
  3060 ** previously selected at compile-time or start-time.
  3061 ** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be
  3062 ** eligible to use [shared cache mode], regardless of whether or not shared
  3063 ** cache is enabled using [sqlite3_enable_shared_cache()].  ^The
  3064 ** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not
  3065 ** participate in [shared cache mode] even if it is enabled.
  3066 **
  3067 ** ^The fourth parameter to sqlite3_open_v2() is the name of the
  3068 ** [sqlite3_vfs] object that defines the operating system interface that
  3069 ** the new database connection should use.  ^If the fourth parameter is
  3070 ** a NULL pointer then the default [sqlite3_vfs] object is used.
  3071 **
  3072 ** ^If the filename is ":memory:", then a private, temporary in-memory database
  3073 ** is created for the connection.  ^This in-memory database will vanish when
  3074 ** the database connection is closed.  Future versions of SQLite might
  3075 ** make use of additional special filenames that begin with the ":" character.
  3076 ** It is recommended that when a database filename actually does begin with
  3077 ** a ":" character you should prefix the filename with a pathname such as
  3078 ** "./" to avoid ambiguity.
  3079 **
  3080 ** ^If the filename is an empty string, then a private, temporary
  3081 ** on-disk database will be created.  ^This private database will be
  3082 ** automatically deleted as soon as the database connection is closed.
  3083 **
  3084 ** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
  3085 **
  3086 ** ^If [URI filename] interpretation is enabled, and the filename argument
  3087 ** begins with "file:", then the filename is interpreted as a URI. ^URI
  3088 ** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
  3089 ** set in the fourth argument to sqlite3_open_v2(), or if it has
  3090 ** been enabled globally using the [SQLITE_CONFIG_URI] option with the
  3091 ** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
  3092 ** As of SQLite version 3.7.7, URI filename interpretation is turned off
  3093 ** by default, but future releases of SQLite might enable URI filename
  3094 ** interpretation by default.  See "[URI filenames]" for additional
  3095 ** information.
  3096 **
  3097 ** URI filenames are parsed according to RFC 3986. ^If the URI contains an
  3098 ** authority, then it must be either an empty string or the string 
  3099 ** "localhost". ^If the authority is not an empty string or "localhost", an 
  3100 ** error is returned to the caller. ^The fragment component of a URI, if 
  3101 ** present, is ignored.
  3102 **
  3103 ** ^SQLite uses the path component of the URI as the name of the disk file
  3104 ** which contains the database. ^If the path begins with a '/' character, 
  3105 ** then it is interpreted as an absolute path. ^If the path does not begin 
  3106 ** with a '/' (meaning that the authority section is omitted from the URI)
  3107 ** then the path is interpreted as a relative path. 
  3108 ** ^(On windows, the first component of an absolute path 
  3109 ** is a drive specification (e.g. "C:").)^
  3110 **
  3111 ** [[core URI query parameters]]
  3112 ** The query component of a URI may contain parameters that are interpreted
  3113 ** either by SQLite itself, or by a [VFS | custom VFS implementation].
  3114 ** SQLite and its built-in [VFSes] interpret the
  3115 ** following query parameters:
  3116 **
  3117 ** <ul>
  3118 **   <li> <b>vfs</b>: ^The "vfs" parameter may be used to specify the name of
  3119 **     a VFS object that provides the operating system interface that should
  3120 **     be used to access the database file on disk. ^If this option is set to
  3121 **     an empty string the default VFS object is used. ^Specifying an unknown
  3122 **     VFS is an error. ^If sqlite3_open_v2() is used and the vfs option is
  3123 **     present, then the VFS specified by the option takes precedence over
  3124 **     the value passed as the fourth parameter to sqlite3_open_v2().
  3125 **
  3126 **   <li> <b>mode</b>: ^(The mode parameter may be set to either "ro", "rw",
  3127 **     "rwc", or "memory". Attempting to set it to any other value is
  3128 **     an error)^. 
  3129 **     ^If "ro" is specified, then the database is opened for read-only 
  3130 **     access, just as if the [SQLITE_OPEN_READONLY] flag had been set in the 
  3131 **     third argument to sqlite3_open_v2(). ^If the mode option is set to 
  3132 **     "rw", then the database is opened for read-write (but not create) 
  3133 **     access, as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had 
  3134 **     been set. ^Value "rwc" is equivalent to setting both 
  3135 **     SQLITE_OPEN_READWRITE and SQLITE_OPEN_CREATE.  ^If the mode option is
  3136 **     set to "memory" then a pure [in-memory database] that never reads
  3137 **     or writes from disk is used. ^It is an error to specify a value for
  3138 **     the mode parameter that is less restrictive than that specified by
  3139 **     the flags passed in the third parameter to sqlite3_open_v2().
  3140 **
  3141 **   <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or
  3142 **     "private". ^Setting it to "shared" is equivalent to setting the
  3143 **     SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to
  3144 **     sqlite3_open_v2(). ^Setting the cache parameter to "private" is 
  3145 **     equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit.
  3146 **     ^If sqlite3_open_v2() is used and the "cache" parameter is present in
  3147 **     a URI filename, its value overrides any behavior requested by setting
  3148 **     SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag.
  3149 **
  3150 **  <li> <b>psow</b>: ^The psow parameter indicates whether or not the
  3151 **     [powersafe overwrite] property does or does not apply to the
  3152 **     storage media on which the database file resides.
  3153 **
  3154 **  <li> <b>nolock</b>: ^The nolock parameter is a boolean query parameter
  3155 **     which if set disables file locking in rollback journal modes.  This
  3156 **     is useful for accessing a database on a filesystem that does not
  3157 **     support locking.  Caution:  Database corruption might result if two
  3158 **     or more processes write to the same database and any one of those
  3159 **     processes uses nolock=1.
  3160 **
  3161 **  <li> <b>immutable</b>: ^The immutable parameter is a boolean query
  3162 **     parameter that indicates that the database file is stored on
  3163 **     read-only media.  ^When immutable is set, SQLite assumes that the
  3164 **     database file cannot be changed, even by a process with higher
  3165 **     privilege, and so the database is opened read-only and all locking
  3166 **     and change detection is disabled.  Caution: Setting the immutable
  3167 **     property on a database file that does in fact change can result
  3168 **     in incorrect query results and/or [SQLITE_CORRUPT] errors.
  3169 **     See also: [SQLITE_IOCAP_IMMUTABLE].
  3170 **       
  3171 ** </ul>
  3172 **
  3173 ** ^Specifying an unknown parameter in the query component of a URI is not an
  3174 ** error.  Future versions of SQLite might understand additional query
  3175 ** parameters.  See "[query parameters with special meaning to SQLite]" for
  3176 ** additional information.
  3177 **
  3178 ** [[URI filename examples]] <h3>URI filename examples</h3>
  3179 **
  3180 ** <table border="1" align=center cellpadding=5>
  3181 ** <tr><th> URI filenames <th> Results
  3182 ** <tr><td> file:data.db <td> 
  3183 **          Open the file "data.db" in the current directory.
  3184 ** <tr><td> file:/home/fred/data.db<br>
  3185 **          file:///home/fred/data.db <br> 
  3186 **          file://localhost/home/fred/data.db <br> <td> 
  3187 **          Open the database file "/home/fred/data.db".
  3188 ** <tr><td> file://darkstar/home/fred/data.db <td> 
  3189 **          An error. "darkstar" is not a recognized authority.
  3190 ** <tr><td style="white-space:nowrap"> 
  3191 **          file:///C:/Documents%20and%20Settings/fred/Desktop/data.db
  3192 **     <td> Windows only: Open the file "data.db" on fred's desktop on drive
  3193 **          C:. Note that the %20 escaping in this example is not strictly 
  3194 **          necessary - space characters can be used literally
  3195 **          in URI filenames.
  3196 ** <tr><td> file:data.db?mode=ro&cache=private <td> 
  3197 **          Open file "data.db" in the current directory for read-only access.
  3198 **          Regardless of whether or not shared-cache mode is enabled by
  3199 **          default, use a private cache.
  3200 ** <tr><td> file:/home/fred/data.db?vfs=unix-dotfile <td>
  3201 **          Open file "/home/fred/data.db". Use the special VFS "unix-dotfile"
  3202 **          that uses dot-files in place of posix advisory locking.
  3203 ** <tr><td> file:data.db?mode=readonly <td> 
  3204 **          An error. "readonly" is not a valid option for the "mode" parameter.
  3205 ** </table>
  3206 **
  3207 ** ^URI hexadecimal escape sequences (%HH) are supported within the path and
  3208 ** query components of a URI. A hexadecimal escape sequence consists of a
  3209 ** percent sign - "%" - followed by exactly two hexadecimal digits 
  3210 ** specifying an octet value. ^Before the path or query components of a
  3211 ** URI filename are interpreted, they are encoded using UTF-8 and all 
  3212 ** hexadecimal escape sequences replaced by a single byte containing the
  3213 ** corresponding octet. If this process generates an invalid UTF-8 encoding,
  3214 ** the results are undefined.
  3215 **
  3216 ** <b>Note to Windows users:</b>  The encoding used for the filename argument
  3217 ** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
  3218 ** codepage is currently defined.  Filenames containing international
  3219 ** characters must be converted to UTF-8 prior to passing them into
  3220 ** sqlite3_open() or sqlite3_open_v2().
  3221 **
  3222 ** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
  3223 ** prior to calling sqlite3_open() or sqlite3_open_v2().  Otherwise, various
  3224 ** features that require the use of temporary files may fail.
  3225 **
  3226 ** See also: [sqlite3_temp_directory]
  3227 */
  3228 SQLITE_API int sqlite3_open(
  3229   const char *filename,   /* Database filename (UTF-8) */
  3230   sqlite3 **ppDb          /* OUT: SQLite db handle */
  3231 );
  3232 SQLITE_API int sqlite3_open16(
  3233   const void *filename,   /* Database filename (UTF-16) */
  3234   sqlite3 **ppDb          /* OUT: SQLite db handle */
  3235 );
  3236 SQLITE_API int sqlite3_open_v2(
  3237   const char *filename,   /* Database filename (UTF-8) */
  3238   sqlite3 **ppDb,         /* OUT: SQLite db handle */
  3239   int flags,              /* Flags */
  3240   const char *zVfs        /* Name of VFS module to use */
  3241 );
  3242 
  3243 /*
  3244 ** CAPI3REF: Obtain Values For URI Parameters
  3245 **
  3246 ** These are utility routines, useful to VFS implementations, that check
  3247 ** to see if a database file was a URI that contained a specific query 
  3248 ** parameter, and if so obtains the value of that query parameter.
  3249 **
  3250 ** If F is the database filename pointer passed into the xOpen() method of 
  3251 ** a VFS implementation when the flags parameter to xOpen() has one or 
  3252 ** more of the [SQLITE_OPEN_URI] or [SQLITE_OPEN_MAIN_DB] bits set and
  3253 ** P is the name of the query parameter, then
  3254 ** sqlite3_uri_parameter(F,P) returns the value of the P
  3255 ** parameter if it exists or a NULL pointer if P does not appear as a 
  3256 ** query parameter on F.  If P is a query parameter of F
  3257 ** has no explicit value, then sqlite3_uri_parameter(F,P) returns
  3258 ** a pointer to an empty string.
  3259 **
  3260 ** The sqlite3_uri_boolean(F,P,B) routine assumes that P is a boolean
  3261 ** parameter and returns true (1) or false (0) according to the value
  3262 ** of P.  The sqlite3_uri_boolean(F,P,B) routine returns true (1) if the
  3263 ** value of query parameter P is one of "yes", "true", or "on" in any
  3264 ** case or if the value begins with a non-zero number.  The 
  3265 ** sqlite3_uri_boolean(F,P,B) routines returns false (0) if the value of
  3266 ** query parameter P is one of "no", "false", or "off" in any case or
  3267 ** if the value begins with a numeric zero.  If P is not a query
  3268 ** parameter on F or if the value of P is does not match any of the
  3269 ** above, then sqlite3_uri_boolean(F,P,B) returns (B!=0).
  3270 **
  3271 ** The sqlite3_uri_int64(F,P,D) routine converts the value of P into a
  3272 ** 64-bit signed integer and returns that integer, or D if P does not
  3273 ** exist.  If the value of P is something other than an integer, then
  3274 ** zero is returned.
  3275 ** 
  3276 ** If F is a NULL pointer, then sqlite3_uri_parameter(F,P) returns NULL and
  3277 ** sqlite3_uri_boolean(F,P,B) returns B.  If F is not a NULL pointer and
  3278 ** is not a database file pathname pointer that SQLite passed into the xOpen
  3279 ** VFS method, then the behavior of this routine is undefined and probably
  3280 ** undesirable.
  3281 */
  3282 SQLITE_API const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam);
  3283 SQLITE_API int sqlite3_uri_boolean(const char *zFile, const char *zParam, int bDefault);
  3284 SQLITE_API sqlite3_int64 sqlite3_uri_int64(const char*, const char*, sqlite3_int64);
  3285 
  3286 
  3287 /*
  3288 ** CAPI3REF: Error Codes And Messages
  3289 ** METHOD: sqlite3
  3290 **
  3291 ** ^If the most recent sqlite3_* API call associated with 
  3292 ** [database connection] D failed, then the sqlite3_errcode(D) interface
  3293 ** returns the numeric [result code] or [extended result code] for that
  3294 ** API call.
  3295 ** If the most recent API call was successful,
  3296 ** then the return value from sqlite3_errcode() is undefined.
  3297 ** ^The sqlite3_extended_errcode()
  3298 ** interface is the same except that it always returns the 
  3299 ** [extended result code] even when extended result codes are
  3300 ** disabled.
  3301 **
  3302 ** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
  3303 ** text that describes the error, as either UTF-8 or UTF-16 respectively.
  3304 ** ^(Memory to hold the error message string is managed internally.
  3305 ** The application does not need to worry about freeing the result.
  3306 ** However, the error string might be overwritten or deallocated by
  3307 ** subsequent calls to other SQLite interface functions.)^
  3308 **
  3309 ** ^The sqlite3_errstr() interface returns the English-language text
  3310 ** that describes the [result code], as UTF-8.
  3311 ** ^(Memory to hold the error message string is managed internally
  3312 ** and must not be freed by the application)^.
  3313 **
  3314 ** When the serialized [threading mode] is in use, it might be the
  3315 ** case that a second error occurs on a separate thread in between
  3316 ** the time of the first error and the call to these interfaces.
  3317 ** When that happens, the second error will be reported since these
  3318 ** interfaces always report the most recent result.  To avoid
  3319 ** this, each thread can obtain exclusive use of the [database connection] D
  3320 ** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
  3321 ** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
  3322 ** all calls to the interfaces listed here are completed.
  3323 **
  3324 ** If an interface fails with SQLITE_MISUSE, that means the interface
  3325 ** was invoked incorrectly by the application.  In that case, the
  3326 ** error code and message may or may not be set.
  3327 */
  3328 SQLITE_API int sqlite3_errcode(sqlite3 *db);
  3329 SQLITE_API int sqlite3_extended_errcode(sqlite3 *db);
  3330 SQLITE_API const char *sqlite3_errmsg(sqlite3*);
  3331 SQLITE_API const void *sqlite3_errmsg16(sqlite3*);
  3332 SQLITE_API const char *sqlite3_errstr(int);
  3333 
  3334 /*
  3335 ** CAPI3REF: Prepared Statement Object
  3336 ** KEYWORDS: {prepared statement} {prepared statements}
  3337 **
  3338 ** An instance of this object represents a single SQL statement that
  3339 ** has been compiled into binary form and is ready to be evaluated.
  3340 **
  3341 ** Think of each SQL statement as a separate computer program.  The
  3342 ** original SQL text is source code.  A prepared statement object 
  3343 ** is the compiled object code.  All SQL must be converted into a
  3344 ** prepared statement before it can be run.
  3345 **
  3346 ** The life-cycle of a prepared statement object usually goes like this:
  3347 **
  3348 ** <ol>
  3349 ** <li> Create the prepared statement object using [sqlite3_prepare_v2()].
  3350 ** <li> Bind values to [parameters] using the sqlite3_bind_*()
  3351 **      interfaces.
  3352 ** <li> Run the SQL by calling [sqlite3_step()] one or more times.
  3353 ** <li> Reset the prepared statement using [sqlite3_reset()] then go back
  3354 **      to step 2.  Do this zero or more times.
  3355 ** <li> Destroy the object using [sqlite3_finalize()].
  3356 ** </ol>
  3357 */
  3358 typedef struct sqlite3_stmt sqlite3_stmt;
  3359 
  3360 /*
  3361 ** CAPI3REF: Run-time Limits
  3362 ** METHOD: sqlite3
  3363 **
  3364 ** ^(This interface allows the size of various constructs to be limited
  3365 ** on a connection by connection basis.  The first parameter is the
  3366 ** [database connection] whose limit is to be set or queried.  The
  3367 ** second parameter is one of the [limit categories] that define a
  3368 ** class of constructs to be size limited.  The third parameter is the
  3369 ** new limit for that construct.)^
  3370 **
  3371 ** ^If the new limit is a negative number, the limit is unchanged.
  3372 ** ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a 
  3373 ** [limits | hard upper bound]
  3374 ** set at compile-time by a C preprocessor macro called
  3375 ** [limits | SQLITE_MAX_<i>NAME</i>].
  3376 ** (The "_LIMIT_" in the name is changed to "_MAX_".))^
  3377 ** ^Attempts to increase a limit above its hard upper bound are
  3378 ** silently truncated to the hard upper bound.
  3379 **
  3380 ** ^Regardless of whether or not the limit was changed, the 
  3381 ** [sqlite3_limit()] interface returns the prior value of the limit.
  3382 ** ^Hence, to find the current value of a limit without changing it,
  3383 ** simply invoke this interface with the third parameter set to -1.
  3384 **
  3385 ** Run-time limits are intended for use in applications that manage
  3386 ** both their own internal database and also databases that are controlled
  3387 ** by untrusted external sources.  An example application might be a
  3388 ** web browser that has its own databases for storing history and
  3389 ** separate databases controlled by JavaScript applications downloaded
  3390 ** off the Internet.  The internal databases can be given the
  3391 ** large, default limits.  Databases managed by external sources can
  3392 ** be given much smaller limits designed to prevent a denial of service
  3393 ** attack.  Developers might also want to use the [sqlite3_set_authorizer()]
  3394 ** interface to further control untrusted SQL.  The size of the database
  3395 ** created by an untrusted script can be contained using the
  3396 ** [max_page_count] [PRAGMA].
  3397 **
  3398 ** New run-time limit categories may be added in future releases.
  3399 */
  3400 SQLITE_API int sqlite3_limit(sqlite3*, int id, int newVal);
  3401 
  3402 /*
  3403 ** CAPI3REF: Run-Time Limit Categories
  3404 ** KEYWORDS: {limit category} {*limit categories}
  3405 **
  3406 ** These constants define various performance limits
  3407 ** that can be lowered at run-time using [sqlite3_limit()].
  3408 ** The synopsis of the meanings of the various limits is shown below.
  3409 ** Additional information is available at [limits | Limits in SQLite].
  3410 **
  3411 ** <dl>
  3412 ** [[SQLITE_LIMIT_LENGTH]] ^(<dt>SQLITE_LIMIT_LENGTH</dt>
  3413 ** <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^
  3414 **
  3415 ** [[SQLITE_LIMIT_SQL_LENGTH]] ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt>
  3416 ** <dd>The maximum length of an SQL statement, in bytes.</dd>)^
  3417 **
  3418 ** [[SQLITE_LIMIT_COLUMN]] ^(<dt>SQLITE_LIMIT_COLUMN</dt>
  3419 ** <dd>The maximum number of columns in a table definition or in the
  3420 ** result set of a [SELECT] or the maximum number of columns in an index
  3421 ** or in an ORDER BY or GROUP BY clause.</dd>)^
  3422 **
  3423 ** [[SQLITE_LIMIT_EXPR_DEPTH]] ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
  3424 ** <dd>The maximum depth of the parse tree on any expression.</dd>)^
  3425 **
  3426 ** [[SQLITE_LIMIT_COMPOUND_SELECT]] ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
  3427 ** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^
  3428 **
  3429 ** [[SQLITE_LIMIT_VDBE_OP]] ^(<dt>SQLITE_LIMIT_VDBE_OP</dt>
  3430 ** <dd>The maximum number of instructions in a virtual machine program
  3431 ** used to implement an SQL statement.  If [sqlite3_prepare_v2()] or
  3432 ** the equivalent tries to allocate space for more than this many opcodes
  3433 ** in a single prepared statement, an SQLITE_NOMEM error is returned.</dd>)^
  3434 **
  3435 ** [[SQLITE_LIMIT_FUNCTION_ARG]] ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
  3436 ** <dd>The maximum number of arguments on a function.</dd>)^
  3437 **
  3438 ** [[SQLITE_LIMIT_ATTACHED]] ^(<dt>SQLITE_LIMIT_ATTACHED</dt>
  3439 ** <dd>The maximum number of [ATTACH | attached databases].)^</dd>
  3440 **
  3441 ** [[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]]
  3442 ** ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
  3443 ** <dd>The maximum length of the pattern argument to the [LIKE] or
  3444 ** [GLOB] operators.</dd>)^
  3445 **
  3446 ** [[SQLITE_LIMIT_VARIABLE_NUMBER]]
  3447 ** ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
  3448 ** <dd>The maximum index number of any [parameter] in an SQL statement.)^
  3449 **
  3450 ** [[SQLITE_LIMIT_TRIGGER_DEPTH]] ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt>
  3451 ** <dd>The maximum depth of recursion for triggers.</dd>)^
  3452 **
  3453 ** [[SQLITE_LIMIT_WORKER_THREADS]] ^(<dt>SQLITE_LIMIT_WORKER_THREADS</dt>
  3454 ** <dd>The maximum number of auxiliary worker threads that a single
  3455 ** [prepared statement] may start.</dd>)^
  3456 ** </dl>
  3457 */
  3458 #define SQLITE_LIMIT_LENGTH                    0
  3459 #define SQLITE_LIMIT_SQL_LENGTH                1
  3460 #define SQLITE_LIMIT_COLUMN                    2
  3461 #define SQLITE_LIMIT_EXPR_DEPTH                3
  3462 #define SQLITE_LIMIT_COMPOUND_SELECT           4
  3463 #define SQLITE_LIMIT_VDBE_OP                   5
  3464 #define SQLITE_LIMIT_FUNCTION_ARG              6
  3465 #define SQLITE_LIMIT_ATTACHED                  7
  3466 #define SQLITE_LIMIT_LIKE_PATTERN_LENGTH       8
  3467 #define SQLITE_LIMIT_VARIABLE_NUMBER           9
  3468 #define SQLITE_LIMIT_TRIGGER_DEPTH            10
  3469 #define SQLITE_LIMIT_WORKER_THREADS           11
  3470 
  3471 
  3472 /*
  3473 ** CAPI3REF: Compiling An SQL Statement
  3474 ** KEYWORDS: {SQL statement compiler}
  3475 ** METHOD: sqlite3
  3476 ** CONSTRUCTOR: sqlite3_stmt
  3477 **
  3478 ** To execute an SQL query, it must first be compiled into a byte-code
  3479 ** program using one of these routines.
  3480 **
  3481 ** The first argument, "db", is a [database connection] obtained from a
  3482 ** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or
  3483 ** [sqlite3_open16()].  The database connection must not have been closed.
  3484 **
  3485 ** The second argument, "zSql", is the statement to be compiled, encoded
  3486 ** as either UTF-8 or UTF-16.  The sqlite3_prepare() and sqlite3_prepare_v2()
  3487 ** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()
  3488 ** use UTF-16.
  3489 **
  3490 ** ^If the nByte argument is negative, then zSql is read up to the
  3491 ** first zero terminator. ^If nByte is positive, then it is the
  3492 ** number of bytes read from zSql.  ^If nByte is zero, then no prepared
  3493 ** statement is generated.
  3494 ** If the caller knows that the supplied string is nul-terminated, then
  3495 ** there is a small performance advantage to passing an nByte parameter that
  3496 ** is the number of bytes in the input string <i>including</i>
  3497 ** the nul-terminator.
  3498 **
  3499 ** ^If pzTail is not NULL then *pzTail is made to point to the first byte
  3500 ** past the end of the first SQL statement in zSql.  These routines only
  3501 ** compile the first statement in zSql, so *pzTail is left pointing to
  3502 ** what remains uncompiled.
  3503 **
  3504 ** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
  3505 ** executed using [sqlite3_step()].  ^If there is an error, *ppStmt is set
  3506 ** to NULL.  ^If the input text contains no SQL (if the input is an empty
  3507 ** string or a comment) then *ppStmt is set to NULL.
  3508 ** The calling procedure is responsible for deleting the compiled
  3509 ** SQL statement using [sqlite3_finalize()] after it has finished with it.
  3510 ** ppStmt may not be NULL.
  3511 **
  3512 ** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK];
  3513 ** otherwise an [error code] is returned.
  3514 **
  3515 ** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are
  3516 ** recommended for all new programs. The two older interfaces are retained
  3517 ** for backwards compatibility, but their use is discouraged.
  3518 ** ^In the "v2" interfaces, the prepared statement
  3519 ** that is returned (the [sqlite3_stmt] object) contains a copy of the
  3520 ** original SQL text. This causes the [sqlite3_step()] interface to
  3521 ** behave differently in three ways:
  3522 **
  3523 ** <ol>
  3524 ** <li>
  3525 ** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
  3526 ** always used to do, [sqlite3_step()] will automatically recompile the SQL
  3527 ** statement and try to run it again. As many as [SQLITE_MAX_SCHEMA_RETRY]
  3528 ** retries will occur before sqlite3_step() gives up and returns an error.
  3529 ** </li>
  3530 **
  3531 ** <li>
  3532 ** ^When an error occurs, [sqlite3_step()] will return one of the detailed
  3533 ** [error codes] or [extended error codes].  ^The legacy behavior was that
  3534 ** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
  3535 ** and the application would have to make a second call to [sqlite3_reset()]
  3536 ** in order to find the underlying cause of the problem. With the "v2" prepare
  3537 ** interfaces, the underlying reason for the error is returned immediately.
  3538 ** </li>
  3539 **
  3540 ** <li>
  3541 ** ^If the specific value bound to [parameter | host parameter] in the 
  3542 ** WHERE clause might influence the choice of query plan for a statement,
  3543 ** then the statement will be automatically recompiled, as if there had been 
  3544 ** a schema change, on the first  [sqlite3_step()] call following any change
  3545 ** to the [sqlite3_bind_text | bindings] of that [parameter]. 
  3546 ** ^The specific value of WHERE-clause [parameter] might influence the 
  3547 ** choice of query plan if the parameter is the left-hand side of a [LIKE]
  3548 ** or [GLOB] operator or if the parameter is compared to an indexed column
  3549 ** and the [SQLITE_ENABLE_STAT3] compile-time option is enabled.
  3550 ** </li>
  3551 ** </ol>
  3552 */
  3553 SQLITE_API int sqlite3_prepare(
  3554   sqlite3 *db,            /* Database handle */
  3555   const char *zSql,       /* SQL statement, UTF-8 encoded */
  3556   int nByte,              /* Maximum length of zSql in bytes. */
  3557   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3558   const char **pzTail     /* OUT: Pointer to unused portion of zSql */
  3559 );
  3560 SQLITE_API int sqlite3_prepare_v2(
  3561   sqlite3 *db,            /* Database handle */
  3562   const char *zSql,       /* SQL statement, UTF-8 encoded */
  3563   int nByte,              /* Maximum length of zSql in bytes. */
  3564   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3565   const char **pzTail     /* OUT: Pointer to unused portion of zSql */
  3566 );
  3567 SQLITE_API int sqlite3_prepare16(
  3568   sqlite3 *db,            /* Database handle */
  3569   const void *zSql,       /* SQL statement, UTF-16 encoded */
  3570   int nByte,              /* Maximum length of zSql in bytes. */
  3571   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3572   const void **pzTail     /* OUT: Pointer to unused portion of zSql */
  3573 );
  3574 SQLITE_API int sqlite3_prepare16_v2(
  3575   sqlite3 *db,            /* Database handle */
  3576   const void *zSql,       /* SQL statement, UTF-16 encoded */
  3577   int nByte,              /* Maximum length of zSql in bytes. */
  3578   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3579   const void **pzTail     /* OUT: Pointer to unused portion of zSql */
  3580 );
  3581 
  3582 /*
  3583 ** CAPI3REF: Retrieving Statement SQL
  3584 ** METHOD: sqlite3_stmt
  3585 **
  3586 ** ^The sqlite3_sql(P) interface returns a pointer to a copy of the UTF-8
  3587 ** SQL text used to create [prepared statement] P if P was
  3588 ** created by either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
  3589 ** ^The sqlite3_expanded_sql(P) interface returns a pointer to a UTF-8
  3590 ** string containing the SQL text of prepared statement P with
  3591 ** [bound parameters] expanded.
  3592 **
  3593 ** ^(For example, if a prepared statement is created using the SQL
  3594 ** text "SELECT $abc,:xyz" and if parameter $abc is bound to integer 2345
  3595 ** and parameter :xyz is unbound, then sqlite3_sql() will return
  3596 ** the original string, "SELECT $abc,:xyz" but sqlite3_expanded_sql()
  3597 ** will return "SELECT 2345,NULL".)^
  3598 **
  3599 ** ^The sqlite3_expanded_sql() interface returns NULL if insufficient memory
  3600 ** is available to hold the result, or if the result would exceed the
  3601 ** the maximum string length determined by the [SQLITE_LIMIT_LENGTH].
  3602 **
  3603 ** ^The [SQLITE_TRACE_SIZE_LIMIT] compile-time option limits the size of
  3604 ** bound parameter expansions.  ^The [SQLITE_OMIT_TRACE] compile-time
  3605 ** option causes sqlite3_expanded_sql() to always return NULL.
  3606 **
  3607 ** ^The string returned by sqlite3_sql(P) is managed by SQLite and is
  3608 ** automatically freed when the prepared statement is finalized.
  3609 ** ^The string returned by sqlite3_expanded_sql(P), on the other hand,
  3610 ** is obtained from [sqlite3_malloc()] and must be free by the application
  3611 ** by passing it to [sqlite3_free()].
  3612 */
  3613 SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt);
  3614 SQLITE_API char *sqlite3_expanded_sql(sqlite3_stmt *pStmt);
  3615 
  3616 /*
  3617 ** CAPI3REF: Determine If An SQL Statement Writes The Database
  3618 ** METHOD: sqlite3_stmt
  3619 **
  3620 ** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if
  3621 ** and only if the [prepared statement] X makes no direct changes to
  3622 ** the content of the database file.
  3623 **
  3624 ** Note that [application-defined SQL functions] or
  3625 ** [virtual tables] might change the database indirectly as a side effect.  
  3626 ** ^(For example, if an application defines a function "eval()" that 
  3627 ** calls [sqlite3_exec()], then the following SQL statement would
  3628 ** change the database file through side-effects:
  3629 **
  3630 ** <blockquote><pre>
  3631 **    SELECT eval('DELETE FROM t1') FROM t2;
  3632 ** </pre></blockquote>
  3633 **
  3634 ** But because the [SELECT] statement does not change the database file
  3635 ** directly, sqlite3_stmt_readonly() would still return true.)^
  3636 **
  3637 ** ^Transaction control statements such as [BEGIN], [COMMIT], [ROLLBACK],
  3638 ** [SAVEPOINT], and [RELEASE] cause sqlite3_stmt_readonly() to return true,
  3639 ** since the statements themselves do not actually modify the database but
  3640 ** rather they control the timing of when other statements modify the 
  3641 ** database.  ^The [ATTACH] and [DETACH] statements also cause
  3642 ** sqlite3_stmt_readonly() to return true since, while those statements
  3643 ** change the configuration of a database connection, they do not make 
  3644 ** changes to the content of the database files on disk.
  3645 ** ^The sqlite3_stmt_readonly() interface returns true for [BEGIN] since
  3646 ** [BEGIN] merely sets internal flags, but the [BEGIN|BEGIN IMMEDIATE] and
  3647 ** [BEGIN|BEGIN EXCLUSIVE] commands do touch the database and so
  3648 ** sqlite3_stmt_readonly() returns false for those commands.
  3649 */
  3650 SQLITE_API int sqlite3_stmt_readonly(sqlite3_stmt *pStmt);
  3651 
  3652 /*
  3653 ** CAPI3REF: Determine If A Prepared Statement Has Been Reset
  3654 ** METHOD: sqlite3_stmt
  3655 **
  3656 ** ^The sqlite3_stmt_busy(S) interface returns true (non-zero) if the
  3657 ** [prepared statement] S has been stepped at least once using 
  3658 ** [sqlite3_step(S)] but has neither run to completion (returned
  3659 ** [SQLITE_DONE] from [sqlite3_step(S)]) nor
  3660 ** been reset using [sqlite3_reset(S)].  ^The sqlite3_stmt_busy(S)
  3661 ** interface returns false if S is a NULL pointer.  If S is not a 
  3662 ** NULL pointer and is not a pointer to a valid [prepared statement]
  3663 ** object, then the behavior is undefined and probably undesirable.
  3664 **
  3665 ** This interface can be used in combination [sqlite3_next_stmt()]
  3666 ** to locate all prepared statements associated with a database 
  3667 ** connection that are in need of being reset.  This can be used,
  3668 ** for example, in diagnostic routines to search for prepared 
  3669 ** statements that are holding a transaction open.
  3670 */
  3671 SQLITE_API int sqlite3_stmt_busy(sqlite3_stmt*);
  3672 
  3673 /*
  3674 ** CAPI3REF: Dynamically Typed Value Object
  3675 ** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
  3676 **
  3677 ** SQLite uses the sqlite3_value object to represent all values
  3678 ** that can be stored in a database table. SQLite uses dynamic typing
  3679 ** for the values it stores.  ^Values stored in sqlite3_value objects
  3680 ** can be integers, floating point values, strings, BLOBs, or NULL.
  3681 **
  3682 ** An sqlite3_value object may be either "protected" or "unprotected".
  3683 ** Some interfaces require a protected sqlite3_value.  Other interfaces
  3684 ** will accept either a protected or an unprotected sqlite3_value.
  3685 ** Every interface that accepts sqlite3_value arguments specifies
  3686 ** whether or not it requires a protected sqlite3_value.  The
  3687 ** [sqlite3_value_dup()] interface can be used to construct a new 
  3688 ** protected sqlite3_value from an unprotected sqlite3_value.
  3689 **
  3690 ** The terms "protected" and "unprotected" refer to whether or not
  3691 ** a mutex is held.  An internal mutex is held for a protected
  3692 ** sqlite3_value object but no mutex is held for an unprotected
  3693 ** sqlite3_value object.  If SQLite is compiled to be single-threaded
  3694 ** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
  3695 ** or if SQLite is run in one of reduced mutex modes 
  3696 ** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
  3697 ** then there is no distinction between protected and unprotected
  3698 ** sqlite3_value objects and they can be used interchangeably.  However,
  3699 ** for maximum code portability it is recommended that applications
  3700 ** still make the distinction between protected and unprotected
  3701 ** sqlite3_value objects even when not strictly required.
  3702 **
  3703 ** ^The sqlite3_value objects that are passed as parameters into the
  3704 ** implementation of [application-defined SQL functions] are protected.
  3705 ** ^The sqlite3_value object returned by
  3706 ** [sqlite3_column_value()] is unprotected.
  3707 ** Unprotected sqlite3_value objects may only be used with
  3708 ** [sqlite3_result_value()] and [sqlite3_bind_value()].
  3709 ** The [sqlite3_value_blob | sqlite3_value_type()] family of
  3710 ** interfaces require protected sqlite3_value objects.
  3711 */
  3712 typedef struct sqlite3_value sqlite3_value;
  3713 
  3714 /*
  3715 ** CAPI3REF: SQL Function Context Object
  3716 **
  3717 ** The context in which an SQL function executes is stored in an
  3718 ** sqlite3_context object.  ^A pointer to an sqlite3_context object
  3719 ** is always first parameter to [application-defined SQL functions].
  3720 ** The application-defined SQL function implementation will pass this
  3721 ** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
  3722 ** [sqlite3_aggregate_context()], [sqlite3_user_data()],
  3723 ** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
  3724 ** and/or [sqlite3_set_auxdata()].
  3725 */
  3726 typedef struct sqlite3_context sqlite3_context;
  3727 
  3728 /*
  3729 ** CAPI3REF: Binding Values To Prepared Statements
  3730 ** KEYWORDS: {host parameter} {host parameters} {host parameter name}
  3731 ** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
  3732 ** METHOD: sqlite3_stmt
  3733 **
  3734 ** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants,
  3735 ** literals may be replaced by a [parameter] that matches one of following
  3736 ** templates:
  3737 **
  3738 ** <ul>
  3739 ** <li>  ?
  3740 ** <li>  ?NNN
  3741 ** <li>  :VVV
  3742 ** <li>  @VVV
  3743 ** <li>  $VVV
  3744 ** </ul>
  3745 **
  3746 ** In the templates above, NNN represents an integer literal,
  3747 ** and VVV represents an alphanumeric identifier.)^  ^The values of these
  3748 ** parameters (also called "host parameter names" or "SQL parameters")
  3749 ** can be set using the sqlite3_bind_*() routines defined here.
  3750 **
  3751 ** ^The first argument to the sqlite3_bind_*() routines is always
  3752 ** a pointer to the [sqlite3_stmt] object returned from
  3753 ** [sqlite3_prepare_v2()] or its variants.
  3754 **
  3755 ** ^The second argument is the index of the SQL parameter to be set.
  3756 ** ^The leftmost SQL parameter has an index of 1.  ^When the same named
  3757 ** SQL parameter is used more than once, second and subsequent
  3758 ** occurrences have the same index as the first occurrence.
  3759 ** ^The index for named parameters can be looked up using the
  3760 ** [sqlite3_bind_parameter_index()] API if desired.  ^The index
  3761 ** for "?NNN" parameters is the value of NNN.
  3762 ** ^The NNN value must be between 1 and the [sqlite3_limit()]
  3763 ** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
  3764 **
  3765 ** ^The third argument is the value to bind to the parameter.
  3766 ** ^If the third parameter to sqlite3_bind_text() or sqlite3_bind_text16()
  3767 ** or sqlite3_bind_blob() is a NULL pointer then the fourth parameter
  3768 ** is ignored and the end result is the same as sqlite3_bind_null().
  3769 **
  3770 ** ^(In those routines that have a fourth argument, its value is the
  3771 ** number of bytes in the parameter.  To be clear: the value is the
  3772 ** number of <u>bytes</u> in the value, not the number of characters.)^
  3773 ** ^If the fourth parameter to sqlite3_bind_text() or sqlite3_bind_text16()
  3774 ** is negative, then the length of the string is
  3775 ** the number of bytes up to the first zero terminator.
  3776 ** If the fourth parameter to sqlite3_bind_blob() is negative, then
  3777 ** the behavior is undefined.
  3778 ** If a non-negative fourth parameter is provided to sqlite3_bind_text()
  3779 ** or sqlite3_bind_text16() or sqlite3_bind_text64() then
  3780 ** that parameter must be the byte offset
  3781 ** where the NUL terminator would occur assuming the string were NUL
  3782 ** terminated.  If any NUL characters occur at byte offsets less than 
  3783 ** the value of the fourth parameter then the resulting string value will
  3784 ** contain embedded NULs.  The result of expressions involving strings
  3785 ** with embedded NULs is undefined.
  3786 **
  3787 ** ^The fifth argument to the BLOB and string binding interfaces
  3788 ** is a destructor used to dispose of the BLOB or
  3789 ** string after SQLite has finished with it.  ^The destructor is called
  3790 ** to dispose of the BLOB or string even if the call to bind API fails.
  3791 ** ^If the fifth argument is
  3792 ** the special value [SQLITE_STATIC], then SQLite assumes that the
  3793 ** information is in static, unmanaged space and does not need to be freed.
  3794 ** ^If the fifth argument has the value [SQLITE_TRANSIENT], then
  3795 ** SQLite makes its own private copy of the data immediately, before
  3796 ** the sqlite3_bind_*() routine returns.
  3797 **
  3798 ** ^The sixth argument to sqlite3_bind_text64() must be one of
  3799 ** [SQLITE_UTF8], [SQLITE_UTF16], [SQLITE_UTF16BE], or [SQLITE_UTF16LE]
  3800 ** to specify the encoding of the text in the third parameter.  If
  3801 ** the sixth argument to sqlite3_bind_text64() is not one of the
  3802 ** allowed values shown above, or if the text encoding is different
  3803 ** from the encoding specified by the sixth parameter, then the behavior
  3804 ** is undefined.
  3805 **
  3806 ** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
  3807 ** is filled with zeroes.  ^A zeroblob uses a fixed amount of memory
  3808 ** (just an integer to hold its size) while it is being processed.
  3809 ** Zeroblobs are intended to serve as placeholders for BLOBs whose
  3810 ** content is later written using
  3811 ** [sqlite3_blob_open | incremental BLOB I/O] routines.
  3812 ** ^A negative value for the zeroblob results in a zero-length BLOB.
  3813 **
  3814 ** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer
  3815 ** for the [prepared statement] or with a prepared statement for which
  3816 ** [sqlite3_step()] has been called more recently than [sqlite3_reset()],
  3817 ** then the call will return [SQLITE_MISUSE].  If any sqlite3_bind_()
  3818 ** routine is passed a [prepared statement] that has been finalized, the
  3819 ** result is undefined and probably harmful.
  3820 **
  3821 ** ^Bindings are not cleared by the [sqlite3_reset()] routine.
  3822 ** ^Unbound parameters are interpreted as NULL.
  3823 **
  3824 ** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an
  3825 ** [error code] if anything goes wrong.
  3826 ** ^[SQLITE_TOOBIG] might be returned if the size of a string or BLOB
  3827 ** exceeds limits imposed by [sqlite3_limit]([SQLITE_LIMIT_LENGTH]) or
  3828 ** [SQLITE_MAX_LENGTH].
  3829 ** ^[SQLITE_RANGE] is returned if the parameter
  3830 ** index is out of range.  ^[SQLITE_NOMEM] is returned if malloc() fails.
  3831 **
  3832 ** See also: [sqlite3_bind_parameter_count()],
  3833 ** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
  3834 */
  3835 SQLITE_API int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
  3836 SQLITE_API int sqlite3_bind_blob64(sqlite3_stmt*, int, const void*, sqlite3_uint64,
  3837                         void(*)(void*));
  3838 SQLITE_API int sqlite3_bind_double(sqlite3_stmt*, int, double);
  3839 SQLITE_API int sqlite3_bind_int(sqlite3_stmt*, int, int);
  3840 SQLITE_API int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);
  3841 SQLITE_API int sqlite3_bind_null(sqlite3_stmt*, int);
  3842 SQLITE_API int sqlite3_bind_text(sqlite3_stmt*,int,const char*,int,void(*)(void*));
  3843 SQLITE_API int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
  3844 SQLITE_API int sqlite3_bind_text64(sqlite3_stmt*, int, const char*, sqlite3_uint64,
  3845                          void(*)(void*), unsigned char encoding);
  3846 SQLITE_API int sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*);
  3847 SQLITE_API int sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n);
  3848 SQLITE_API int sqlite3_bind_zeroblob64(sqlite3_stmt*, int, sqlite3_uint64);
  3849 
  3850 /*
  3851 ** CAPI3REF: Number Of SQL Parameters
  3852 ** METHOD: sqlite3_stmt
  3853 **
  3854 ** ^This routine can be used to find the number of [SQL parameters]
  3855 ** in a [prepared statement].  SQL parameters are tokens of the
  3856 ** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
  3857 ** placeholders for values that are [sqlite3_bind_blob | bound]
  3858 ** to the parameters at a later time.
  3859 **
  3860 ** ^(This routine actually returns the index of the largest (rightmost)
  3861 ** parameter. For all forms except ?NNN, this will correspond to the
  3862 ** number of unique parameters.  If parameters of the ?NNN form are used,
  3863 ** there may be gaps in the list.)^
  3864 **
  3865 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3866 ** [sqlite3_bind_parameter_name()], and
  3867 ** [sqlite3_bind_parameter_index()].
  3868 */
  3869 SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt*);
  3870 
  3871 /*
  3872 ** CAPI3REF: Name Of A Host Parameter
  3873 ** METHOD: sqlite3_stmt
  3874 **
  3875 ** ^The sqlite3_bind_parameter_name(P,N) interface returns
  3876 ** the name of the N-th [SQL parameter] in the [prepared statement] P.
  3877 ** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
  3878 ** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
  3879 ** respectively.
  3880 ** In other words, the initial ":" or "$" or "@" or "?"
  3881 ** is included as part of the name.)^
  3882 ** ^Parameters of the form "?" without a following integer have no name
  3883 ** and are referred to as "nameless" or "anonymous parameters".
  3884 **
  3885 ** ^The first host parameter has an index of 1, not 0.
  3886 **
  3887 ** ^If the value N is out of range or if the N-th parameter is
  3888 ** nameless, then NULL is returned.  ^The returned string is
  3889 ** always in UTF-8 encoding even if the named parameter was
  3890 ** originally specified as UTF-16 in [sqlite3_prepare16()] or
  3891 ** [sqlite3_prepare16_v2()].
  3892 **
  3893 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3894 ** [sqlite3_bind_parameter_count()], and
  3895 ** [sqlite3_bind_parameter_index()].
  3896 */
  3897 SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt*, int);
  3898 
  3899 /*
  3900 ** CAPI3REF: Index Of A Parameter With A Given Name
  3901 ** METHOD: sqlite3_stmt
  3902 **
  3903 ** ^Return the index of an SQL parameter given its name.  ^The
  3904 ** index value returned is suitable for use as the second
  3905 ** parameter to [sqlite3_bind_blob|sqlite3_bind()].  ^A zero
  3906 ** is returned if no matching parameter is found.  ^The parameter
  3907 ** name must be given in UTF-8 even if the original statement
  3908 ** was prepared from UTF-16 text using [sqlite3_prepare16_v2()].
  3909 **
  3910 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3911 ** [sqlite3_bind_parameter_count()], and
  3912 ** [sqlite3_bind_parameter_name()].
  3913 */
  3914 SQLITE_API int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);
  3915 
  3916 /*
  3917 ** CAPI3REF: Reset All Bindings On A Prepared Statement
  3918 ** METHOD: sqlite3_stmt
  3919 **
  3920 ** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset
  3921 ** the [sqlite3_bind_blob | bindings] on a [prepared statement].
  3922 ** ^Use this routine to reset all host parameters to NULL.
  3923 */
  3924 SQLITE_API int sqlite3_clear_bindings(sqlite3_stmt*);
  3925 
  3926 /*
  3927 ** CAPI3REF: Number Of Columns In A Result Set
  3928 ** METHOD: sqlite3_stmt
  3929 **
  3930 ** ^Return the number of columns in the result set returned by the
  3931 ** [prepared statement]. ^If this routine returns 0, that means the 
  3932 ** [prepared statement] returns no data (for example an [UPDATE]).
  3933 ** ^However, just because this routine returns a positive number does not
  3934 ** mean that one or more rows of data will be returned.  ^A SELECT statement
  3935 ** will always have a positive sqlite3_column_count() but depending on the
  3936 ** WHERE clause constraints and the table content, it might return no rows.
  3937 **
  3938 ** See also: [sqlite3_data_count()]
  3939 */
  3940 SQLITE_API int sqlite3_column_count(sqlite3_stmt *pStmt);
  3941 
  3942 /*
  3943 ** CAPI3REF: Column Names In A Result Set
  3944 ** METHOD: sqlite3_stmt
  3945 **
  3946 ** ^These routines return the name assigned to a particular column
  3947 ** in the result set of a [SELECT] statement.  ^The sqlite3_column_name()
  3948 ** interface returns a pointer to a zero-terminated UTF-8 string
  3949 ** and sqlite3_column_name16() returns a pointer to a zero-terminated
  3950 ** UTF-16 string.  ^The first parameter is the [prepared statement]
  3951 ** that implements the [SELECT] statement. ^The second parameter is the
  3952 ** column number.  ^The leftmost column is number 0.
  3953 **
  3954 ** ^The returned string pointer is valid until either the [prepared statement]
  3955 ** is destroyed by [sqlite3_finalize()] or until the statement is automatically
  3956 ** reprepared by the first call to [sqlite3_step()] for a particular run
  3957 ** or until the next call to
  3958 ** sqlite3_column_name() or sqlite3_column_name16() on the same column.
  3959 **
  3960 ** ^If sqlite3_malloc() fails during the processing of either routine
  3961 ** (for example during a conversion from UTF-8 to UTF-16) then a
  3962 ** NULL pointer is returned.
  3963 **
  3964 ** ^The name of a result column is the value of the "AS" clause for
  3965 ** that column, if there is an AS clause.  If there is no AS clause
  3966 ** then the name of the column is unspecified and may change from
  3967 ** one release of SQLite to the next.
  3968 */
  3969 SQLITE_API const char *sqlite3_column_name(sqlite3_stmt*, int N);
  3970 SQLITE_API const void *sqlite3_column_name16(sqlite3_stmt*, int N);
  3971 
  3972 /*
  3973 ** CAPI3REF: Source Of Data In A Query Result
  3974 ** METHOD: sqlite3_stmt
  3975 **
  3976 ** ^These routines provide a means to determine the database, table, and
  3977 ** table column that is the origin of a particular result column in
  3978 ** [SELECT] statement.
  3979 ** ^The name of the database or table or column can be returned as
  3980 ** either a UTF-8 or UTF-16 string.  ^The _database_ routines return
  3981 ** the database name, the _table_ routines return the table name, and
  3982 ** the origin_ routines return the column name.
  3983 ** ^The returned string is valid until the [prepared statement] is destroyed
  3984 ** using [sqlite3_finalize()] or until the statement is automatically
  3985 ** reprepared by the first call to [sqlite3_step()] for a particular run
  3986 ** or until the same information is requested
  3987 ** again in a different encoding.
  3988 **
  3989 ** ^The names returned are the original un-aliased names of the
  3990 ** database, table, and column.
  3991 **
  3992 ** ^The first argument to these interfaces is a [prepared statement].
  3993 ** ^These functions return information about the Nth result column returned by
  3994 ** the statement, where N is the second function argument.
  3995 ** ^The left-most column is column 0 for these routines.
  3996 **
  3997 ** ^If the Nth column returned by the statement is an expression or
  3998 ** subquery and is not a column value, then all of these functions return
  3999 ** NULL.  ^These routine might also return NULL if a memory allocation error
  4000 ** occurs.  ^Otherwise, they return the name of the attached database, table,
  4001 ** or column that query result column was extracted from.
  4002 **
  4003 ** ^As with all other SQLite APIs, those whose names end with "16" return
  4004 ** UTF-16 encoded strings and the other functions return UTF-8.
  4005 **
  4006 ** ^These APIs are only available if the library was compiled with the
  4007 ** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol.
  4008 **
  4009 ** If two or more threads call one or more of these routines against the same
  4010 ** prepared statement and column at the same time then the results are
  4011 ** undefined.
  4012 **
  4013 ** If two or more threads call one or more
  4014 ** [sqlite3_column_database_name | column metadata interfaces]
  4015 ** for the same [prepared statement] and result column
  4016 ** at the same time then the results are undefined.
  4017 */
  4018 SQLITE_API const char *sqlite3_column_database_name(sqlite3_stmt*,int);
  4019 SQLITE_API const void *sqlite3_column_database_name16(sqlite3_stmt*,int);
  4020 SQLITE_API const char *sqlite3_column_table_name(sqlite3_stmt*,int);
  4021 SQLITE_API const void *sqlite3_column_table_name16(sqlite3_stmt*,int);
  4022 SQLITE_API const char *sqlite3_column_origin_name(sqlite3_stmt*,int);
  4023 SQLITE_API const void *sqlite3_column_origin_name16(sqlite3_stmt*,int);
  4024 
  4025 /*
  4026 ** CAPI3REF: Declared Datatype Of A Query Result
  4027 ** METHOD: sqlite3_stmt
  4028 **
  4029 ** ^(The first parameter is a [prepared statement].
  4030 ** If this statement is a [SELECT] statement and the Nth column of the
  4031 ** returned result set of that [SELECT] is a table column (not an
  4032 ** expression or subquery) then the declared type of the table
  4033 ** column is returned.)^  ^If the Nth column of the result set is an
  4034 ** expression or subquery, then a NULL pointer is returned.
  4035 ** ^The returned string is always UTF-8 encoded.
  4036 **
  4037 ** ^(For example, given the database schema:
  4038 **
  4039 ** CREATE TABLE t1(c1 VARIANT);
  4040 **
  4041 ** and the following statement to be compiled:
  4042 **
  4043 ** SELECT c1 + 1, c1 FROM t1;
  4044 **
  4045 ** this routine would return the string "VARIANT" for the second result
  4046 ** column (i==1), and a NULL pointer for the first result column (i==0).)^
  4047 **
  4048 ** ^SQLite uses dynamic run-time typing.  ^So just because a column
  4049 ** is declared to contain a particular type does not mean that the
  4050 ** data stored in that column is of the declared type.  SQLite is
  4051 ** strongly typed, but the typing is dynamic not static.  ^Type
  4052 ** is associated with individual values, not with the containers
  4053 ** used to hold those values.
  4054 */
  4055 SQLITE_API const char *sqlite3_column_decltype(sqlite3_stmt*,int);
  4056 SQLITE_API const void *sqlite3_column_decltype16(sqlite3_stmt*,int);
  4057 
  4058 /*
  4059 ** CAPI3REF: Evaluate An SQL Statement
  4060 ** METHOD: sqlite3_stmt
  4061 **
  4062 ** After a [prepared statement] has been prepared using either
  4063 ** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy
  4064 ** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
  4065 ** must be called one or more times to evaluate the statement.
  4066 **
  4067 ** The details of the behavior of the sqlite3_step() interface depend
  4068 ** on whether the statement was prepared using the newer "v2" interface
  4069 ** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy
  4070 ** interface [sqlite3_prepare()] and [sqlite3_prepare16()].  The use of the
  4071 ** new "v2" interface is recommended for new applications but the legacy
  4072 ** interface will continue to be supported.
  4073 **
  4074 ** ^In the legacy interface, the return value will be either [SQLITE_BUSY],
  4075 ** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
  4076 ** ^With the "v2" interface, any of the other [result codes] or
  4077 ** [extended result codes] might be returned as well.
  4078 **
  4079 ** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
  4080 ** database locks it needs to do its job.  ^If the statement is a [COMMIT]
  4081 ** or occurs outside of an explicit transaction, then you can retry the
  4082 ** statement.  If the statement is not a [COMMIT] and occurs within an
  4083 ** explicit transaction then you should rollback the transaction before
  4084 ** continuing.
  4085 **
  4086 ** ^[SQLITE_DONE] means that the statement has finished executing
  4087 ** successfully.  sqlite3_step() should not be called again on this virtual
  4088 ** machine without first calling [sqlite3_reset()] to reset the virtual
  4089 ** machine back to its initial state.
  4090 **
  4091 ** ^If the SQL statement being executed returns any data, then [SQLITE_ROW]
  4092 ** is returned each time a new row of data is ready for processing by the
  4093 ** caller. The values may be accessed using the [column access functions].
  4094 ** sqlite3_step() is called again to retrieve the next row of data.
  4095 **
  4096 ** ^[SQLITE_ERROR] means that a run-time error (such as a constraint
  4097 ** violation) has occurred.  sqlite3_step() should not be called again on
  4098 ** the VM. More information may be found by calling [sqlite3_errmsg()].
  4099 ** ^With the legacy interface, a more specific error code (for example,
  4100 ** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
  4101 ** can be obtained by calling [sqlite3_reset()] on the
  4102 ** [prepared statement].  ^In the "v2" interface,
  4103 ** the more specific error code is returned directly by sqlite3_step().
  4104 **
  4105 ** [SQLITE_MISUSE] means that the this routine was called inappropriately.
  4106 ** Perhaps it was called on a [prepared statement] that has
  4107 ** already been [sqlite3_finalize | finalized] or on one that had
  4108 ** previously returned [SQLITE_ERROR] or [SQLITE_DONE].  Or it could
  4109 ** be the case that the same database connection is being used by two or
  4110 ** more threads at the same moment in time.
  4111 **
  4112 ** For all versions of SQLite up to and including 3.6.23.1, a call to
  4113 ** [sqlite3_reset()] was required after sqlite3_step() returned anything
  4114 ** other than [SQLITE_ROW] before any subsequent invocation of
  4115 ** sqlite3_step().  Failure to reset the prepared statement using 
  4116 ** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
  4117 ** sqlite3_step().  But after [version 3.6.23.1] ([dateof:3.6.23.1],
  4118 ** sqlite3_step() began
  4119 ** calling [sqlite3_reset()] automatically in this circumstance rather
  4120 ** than returning [SQLITE_MISUSE].  This is not considered a compatibility
  4121 ** break because any application that ever receives an SQLITE_MISUSE error
  4122 ** is broken by definition.  The [SQLITE_OMIT_AUTORESET] compile-time option
  4123 ** can be used to restore the legacy behavior.
  4124 **
  4125 ** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
  4126 ** API always returns a generic error code, [SQLITE_ERROR], following any
  4127 ** error other than [SQLITE_BUSY] and [SQLITE_MISUSE].  You must call
  4128 ** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
  4129 ** specific [error codes] that better describes the error.
  4130 ** We admit that this is a goofy design.  The problem has been fixed
  4131 ** with the "v2" interface.  If you prepare all of your SQL statements
  4132 ** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead
  4133 ** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
  4134 ** then the more specific [error codes] are returned directly
  4135 ** by sqlite3_step().  The use of the "v2" interface is recommended.
  4136 */
  4137 SQLITE_API int sqlite3_step(sqlite3_stmt*);
  4138 
  4139 /*
  4140 ** CAPI3REF: Number of columns in a result set
  4141 ** METHOD: sqlite3_stmt
  4142 **
  4143 ** ^The sqlite3_data_count(P) interface returns the number of columns in the
  4144 ** current row of the result set of [prepared statement] P.
  4145 ** ^If prepared statement P does not have results ready to return
  4146 ** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
  4147 ** interfaces) then sqlite3_data_count(P) returns 0.
  4148 ** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
  4149 ** ^The sqlite3_data_count(P) routine returns 0 if the previous call to
  4150 ** [sqlite3_step](P) returned [SQLITE_DONE].  ^The sqlite3_data_count(P)
  4151 ** will return non-zero if previous call to [sqlite3_step](P) returned
  4152 ** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]
  4153 ** where it always returns zero since each step of that multi-step
  4154 ** pragma returns 0 columns of data.
  4155 **
  4156 ** See also: [sqlite3_column_count()]
  4157 */
  4158 SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt);
  4159 
  4160 /*
  4161 ** CAPI3REF: Fundamental Datatypes
  4162 ** KEYWORDS: SQLITE_TEXT
  4163 **
  4164 ** ^(Every value in SQLite has one of five fundamental datatypes:
  4165 **
  4166 ** <ul>
  4167 ** <li> 64-bit signed integer
  4168 ** <li> 64-bit IEEE floating point number
  4169 ** <li> string
  4170 ** <li> BLOB
  4171 ** <li> NULL
  4172 ** </ul>)^
  4173 **
  4174 ** These constants are codes for each of those types.
  4175 **
  4176 ** Note that the SQLITE_TEXT constant was also used in SQLite version 2
  4177 ** for a completely different meaning.  Software that links against both
  4178 ** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
  4179 ** SQLITE_TEXT.
  4180 */
  4181 #define SQLITE_INTEGER  1
  4182 #define SQLITE_FLOAT    2
  4183 #define SQLITE_BLOB     4
  4184 #define SQLITE_NULL     5
  4185 #ifdef SQLITE_TEXT
  4186 # undef SQLITE_TEXT
  4187 #else
  4188 # define SQLITE_TEXT     3
  4189 #endif
  4190 #define SQLITE3_TEXT     3
  4191 
  4192 /*
  4193 ** CAPI3REF: Result Values From A Query
  4194 ** KEYWORDS: {column access functions}
  4195 ** METHOD: sqlite3_stmt
  4196 **
  4197 ** ^These routines return information about a single column of the current
  4198 ** result row of a query.  ^In every case the first argument is a pointer
  4199 ** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
  4200 ** that was returned from [sqlite3_prepare_v2()] or one of its variants)
  4201 ** and the second argument is the index of the column for which information
  4202 ** should be returned. ^The leftmost column of the result set has the index 0.
  4203 ** ^The number of columns in the result can be determined using
  4204 ** [sqlite3_column_count()].
  4205 **
  4206 ** If the SQL statement does not currently point to a valid row, or if the
  4207 ** column index is out of range, the result is undefined.
  4208 ** These routines may only be called when the most recent call to
  4209 ** [sqlite3_step()] has returned [SQLITE_ROW] and neither
  4210 ** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
  4211 ** If any of these routines are called after [sqlite3_reset()] or
  4212 ** [sqlite3_finalize()] or after [sqlite3_step()] has returned
  4213 ** something other than [SQLITE_ROW], the results are undefined.
  4214 ** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
  4215 ** are called from a different thread while any of these routines
  4216 ** are pending, then the results are undefined.
  4217 **
  4218 ** ^The sqlite3_column_type() routine returns the
  4219 ** [SQLITE_INTEGER | datatype code] for the initial data type
  4220 ** of the result column.  ^The returned value is one of [SQLITE_INTEGER],
  4221 ** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL].  The value
  4222 ** returned by sqlite3_column_type() is only meaningful if no type
  4223 ** conversions have occurred as described below.  After a type conversion,
  4224 ** the value returned by sqlite3_column_type() is undefined.  Future
  4225 ** versions of SQLite may change the behavior of sqlite3_column_type()
  4226 ** following a type conversion.
  4227 **
  4228 ** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
  4229 ** routine returns the number of bytes in that BLOB or string.
  4230 ** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts
  4231 ** the string to UTF-8 and then returns the number of bytes.
  4232 ** ^If the result is a numeric value then sqlite3_column_bytes() uses
  4233 ** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
  4234 ** the number of bytes in that string.
  4235 ** ^If the result is NULL, then sqlite3_column_bytes() returns zero.
  4236 **
  4237 ** ^If the result is a BLOB or UTF-16 string then the sqlite3_column_bytes16()
  4238 ** routine returns the number of bytes in that BLOB or string.
  4239 ** ^If the result is a UTF-8 string, then sqlite3_column_bytes16() converts
  4240 ** the string to UTF-16 and then returns the number of bytes.
  4241 ** ^If the result is a numeric value then sqlite3_column_bytes16() uses
  4242 ** [sqlite3_snprintf()] to convert that value to a UTF-16 string and returns
  4243 ** the number of bytes in that string.
  4244 ** ^If the result is NULL, then sqlite3_column_bytes16() returns zero.
  4245 **
  4246 ** ^The values returned by [sqlite3_column_bytes()] and 
  4247 ** [sqlite3_column_bytes16()] do not include the zero terminators at the end
  4248 ** of the string.  ^For clarity: the values returned by
  4249 ** [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] are the number of
  4250 ** bytes in the string, not the number of characters.
  4251 **
  4252 ** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
  4253 ** even empty strings, are always zero-terminated.  ^The return
  4254 ** value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer.
  4255 **
  4256 ** <b>Warning:</b> ^The object returned by [sqlite3_column_value()] is an
  4257 ** [unprotected sqlite3_value] object.  In a multithreaded environment,
  4258 ** an unprotected sqlite3_value object may only be used safely with
  4259 ** [sqlite3_bind_value()] and [sqlite3_result_value()].
  4260 ** If the [unprotected sqlite3_value] object returned by
  4261 ** [sqlite3_column_value()] is used in any other way, including calls
  4262 ** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
  4263 ** or [sqlite3_value_bytes()], the behavior is not threadsafe.
  4264 **
  4265 ** These routines attempt to convert the value where appropriate.  ^For
  4266 ** example, if the internal representation is FLOAT and a text result
  4267 ** is requested, [sqlite3_snprintf()] is used internally to perform the
  4268 ** conversion automatically.  ^(The following table details the conversions
  4269 ** that are applied:
  4270 **
  4271 ** <blockquote>
  4272 ** <table border="1">
  4273 ** <tr><th> Internal<br>Type <th> Requested<br>Type <th>  Conversion
  4274 **
  4275 ** <tr><td>  NULL    <td> INTEGER   <td> Result is 0
  4276 ** <tr><td>  NULL    <td>  FLOAT    <td> Result is 0.0
  4277 ** <tr><td>  NULL    <td>   TEXT    <td> Result is a NULL pointer
  4278 ** <tr><td>  NULL    <td>   BLOB    <td> Result is a NULL pointer
  4279 ** <tr><td> INTEGER  <td>  FLOAT    <td> Convert from integer to float
  4280 ** <tr><td> INTEGER  <td>   TEXT    <td> ASCII rendering of the integer
  4281 ** <tr><td> INTEGER  <td>   BLOB    <td> Same as INTEGER->TEXT
  4282 ** <tr><td>  FLOAT   <td> INTEGER   <td> [CAST] to INTEGER
  4283 ** <tr><td>  FLOAT   <td>   TEXT    <td> ASCII rendering of the float
  4284 ** <tr><td>  FLOAT   <td>   BLOB    <td> [CAST] to BLOB
  4285 ** <tr><td>  TEXT    <td> INTEGER   <td> [CAST] to INTEGER
  4286 ** <tr><td>  TEXT    <td>  FLOAT    <td> [CAST] to REAL
  4287 ** <tr><td>  TEXT    <td>   BLOB    <td> No change
  4288 ** <tr><td>  BLOB    <td> INTEGER   <td> [CAST] to INTEGER
  4289 ** <tr><td>  BLOB    <td>  FLOAT    <td> [CAST] to REAL
  4290 ** <tr><td>  BLOB    <td>   TEXT    <td> Add a zero terminator if needed
  4291 ** </table>
  4292 ** </blockquote>)^
  4293 **
  4294 ** Note that when type conversions occur, pointers returned by prior
  4295 ** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
  4296 ** sqlite3_column_text16() may be invalidated.
  4297 ** Type conversions and pointer invalidations might occur
  4298 ** in the following cases:
  4299 **
  4300 ** <ul>
  4301 ** <li> The initial content is a BLOB and sqlite3_column_text() or
  4302 **      sqlite3_column_text16() is called.  A zero-terminator might
  4303 **      need to be added to the string.</li>
  4304 ** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
  4305 **      sqlite3_column_text16() is called.  The content must be converted
  4306 **      to UTF-16.</li>
  4307 ** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
  4308 **      sqlite3_column_text() is called.  The content must be converted
  4309 **      to UTF-8.</li>
  4310 ** </ul>
  4311 **
  4312 ** ^Conversions between UTF-16be and UTF-16le are always done in place and do
  4313 ** not invalidate a prior pointer, though of course the content of the buffer
  4314 ** that the prior pointer references will have been modified.  Other kinds
  4315 ** of conversion are done in place when it is possible, but sometimes they
  4316 ** are not possible and in those cases prior pointers are invalidated.
  4317 **
  4318 ** The safest policy is to invoke these routines
  4319 ** in one of the following ways:
  4320 **
  4321 ** <ul>
  4322 **  <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
  4323 **  <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
  4324 **  <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
  4325 ** </ul>
  4326 **
  4327 ** In other words, you should call sqlite3_column_text(),
  4328 ** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
  4329 ** into the desired format, then invoke sqlite3_column_bytes() or
  4330 ** sqlite3_column_bytes16() to find the size of the result.  Do not mix calls
  4331 ** to sqlite3_column_text() or sqlite3_column_blob() with calls to
  4332 ** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
  4333 ** with calls to sqlite3_column_bytes().
  4334 **
  4335 ** ^The pointers returned are valid until a type conversion occurs as
  4336 ** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
  4337 ** [sqlite3_finalize()] is called.  ^The memory space used to hold strings
  4338 ** and BLOBs is freed automatically.  Do <em>not</em> pass the pointers returned
  4339 ** from [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
  4340 ** [sqlite3_free()].
  4341 **
  4342 ** ^(If a memory allocation error occurs during the evaluation of any
  4343 ** of these routines, a default value is returned.  The default value
  4344 ** is either the integer 0, the floating point number 0.0, or a NULL
  4345 ** pointer.  Subsequent calls to [sqlite3_errcode()] will return
  4346 ** [SQLITE_NOMEM].)^
  4347 */
  4348 SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
  4349 SQLITE_API int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
  4350 SQLITE_API int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
  4351 SQLITE_API double sqlite3_column_double(sqlite3_stmt*, int iCol);
  4352 SQLITE_API int sqlite3_column_int(sqlite3_stmt*, int iCol);
  4353 SQLITE_API sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
  4354 SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
  4355 SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
  4356 SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
  4357 SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);
  4358 
  4359 /*
  4360 ** CAPI3REF: Destroy A Prepared Statement Object
  4361 ** DESTRUCTOR: sqlite3_stmt
  4362 **
  4363 ** ^The sqlite3_finalize() function is called to delete a [prepared statement].
  4364 ** ^If the most recent evaluation of the statement encountered no errors
  4365 ** or if the statement is never been evaluated, then sqlite3_finalize() returns
  4366 ** SQLITE_OK.  ^If the most recent evaluation of statement S failed, then
  4367 ** sqlite3_finalize(S) returns the appropriate [error code] or
  4368 ** [extended error code].
  4369 **
  4370 ** ^The sqlite3_finalize(S) routine can be called at any point during
  4371 ** the life cycle of [prepared statement] S:
  4372 ** before statement S is ever evaluated, after
  4373 ** one or more calls to [sqlite3_reset()], or after any call
  4374 ** to [sqlite3_step()] regardless of whether or not the statement has
  4375 ** completed execution.
  4376 **
  4377 ** ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op.
  4378 **
  4379 ** The application must finalize every [prepared statement] in order to avoid
  4380 ** resource leaks.  It is a grievous error for the application to try to use
  4381 ** a prepared statement after it has been finalized.  Any use of a prepared
  4382 ** statement after it has been finalized can result in undefined and
  4383 ** undesirable behavior such as segfaults and heap corruption.
  4384 */
  4385 SQLITE_API int sqlite3_finalize(sqlite3_stmt *pStmt);
  4386 
  4387 /*
  4388 ** CAPI3REF: Reset A Prepared Statement Object
  4389 ** METHOD: sqlite3_stmt
  4390 **
  4391 ** The sqlite3_reset() function is called to reset a [prepared statement]
  4392 ** object back to its initial state, ready to be re-executed.
  4393 ** ^Any SQL statement variables that had values bound to them using
  4394 ** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
  4395 ** Use [sqlite3_clear_bindings()] to reset the bindings.
  4396 **
  4397 ** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S
  4398 ** back to the beginning of its program.
  4399 **
  4400 ** ^If the most recent call to [sqlite3_step(S)] for the
  4401 ** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
  4402 ** or if [sqlite3_step(S)] has never before been called on S,
  4403 ** then [sqlite3_reset(S)] returns [SQLITE_OK].
  4404 **
  4405 ** ^If the most recent call to [sqlite3_step(S)] for the
  4406 ** [prepared statement] S indicated an error, then
  4407 ** [sqlite3_reset(S)] returns an appropriate [error code].
  4408 **
  4409 ** ^The [sqlite3_reset(S)] interface does not change the values
  4410 ** of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
  4411 */
  4412 SQLITE_API int sqlite3_reset(sqlite3_stmt *pStmt);
  4413 
  4414 /*
  4415 ** CAPI3REF: Create Or Redefine SQL Functions
  4416 ** KEYWORDS: {function creation routines}
  4417 ** KEYWORDS: {application-defined SQL function}
  4418 ** KEYWORDS: {application-defined SQL functions}
  4419 ** METHOD: sqlite3
  4420 **
  4421 ** ^These functions (collectively known as "function creation routines")
  4422 ** are used to add SQL functions or aggregates or to redefine the behavior
  4423 ** of existing SQL functions or aggregates.  The only differences between
  4424 ** these routines are the text encoding expected for
  4425 ** the second parameter (the name of the function being created)
  4426 ** and the presence or absence of a destructor callback for
  4427 ** the application data pointer.
  4428 **
  4429 ** ^The first parameter is the [database connection] to which the SQL
  4430 ** function is to be added.  ^If an application uses more than one database
  4431 ** connection then application-defined SQL functions must be added
  4432 ** to each database connection separately.
  4433 **
  4434 ** ^The second parameter is the name of the SQL function to be created or
  4435 ** redefined.  ^The length of the name is limited to 255 bytes in a UTF-8
  4436 ** representation, exclusive of the zero-terminator.  ^Note that the name
  4437 ** length limit is in UTF-8 bytes, not characters nor UTF-16 bytes.  
  4438 ** ^Any attempt to create a function with a longer name
  4439 ** will result in [SQLITE_MISUSE] being returned.
  4440 **
  4441 ** ^The third parameter (nArg)
  4442 ** is the number of arguments that the SQL function or
  4443 ** aggregate takes. ^If this parameter is -1, then the SQL function or
  4444 ** aggregate may take any number of arguments between 0 and the limit
  4445 ** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]).  If the third
  4446 ** parameter is less than -1 or greater than 127 then the behavior is
  4447 ** undefined.
  4448 **
  4449 ** ^The fourth parameter, eTextRep, specifies what
  4450 ** [SQLITE_UTF8 | text encoding] this SQL function prefers for
  4451 ** its parameters.  The application should set this parameter to
  4452 ** [SQLITE_UTF16LE] if the function implementation invokes 
  4453 ** [sqlite3_value_text16le()] on an input, or [SQLITE_UTF16BE] if the
  4454 ** implementation invokes [sqlite3_value_text16be()] on an input, or
  4455 ** [SQLITE_UTF16] if [sqlite3_value_text16()] is used, or [SQLITE_UTF8]
  4456 ** otherwise.  ^The same SQL function may be registered multiple times using
  4457 ** different preferred text encodings, with different implementations for
  4458 ** each encoding.
  4459 ** ^When multiple implementations of the same function are available, SQLite
  4460 ** will pick the one that involves the least amount of data conversion.
  4461 **
  4462 ** ^The fourth parameter may optionally be ORed with [SQLITE_DETERMINISTIC]
  4463 ** to signal that the function will always return the same result given
  4464 ** the same inputs within a single SQL statement.  Most SQL functions are
  4465 ** deterministic.  The built-in [random()] SQL function is an example of a
  4466 ** function that is not deterministic.  The SQLite query planner is able to
  4467 ** perform additional optimizations on deterministic functions, so use
  4468 ** of the [SQLITE_DETERMINISTIC] flag is recommended where possible.
  4469 **
  4470 ** ^(The fifth parameter is an arbitrary pointer.  The implementation of the
  4471 ** function can gain access to this pointer using [sqlite3_user_data()].)^
  4472 **
  4473 ** ^The sixth, seventh and eighth parameters, xFunc, xStep and xFinal, are
  4474 ** pointers to C-language functions that implement the SQL function or
  4475 ** aggregate. ^A scalar SQL function requires an implementation of the xFunc
  4476 ** callback only; NULL pointers must be passed as the xStep and xFinal
  4477 ** parameters. ^An aggregate SQL function requires an implementation of xStep
  4478 ** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
  4479 ** SQL function or aggregate, pass NULL pointers for all three function
  4480 ** callbacks.
  4481 **
  4482 ** ^(If the ninth parameter to sqlite3_create_function_v2() is not NULL,
  4483 ** then it is destructor for the application data pointer. 
  4484 ** The destructor is invoked when the function is deleted, either by being
  4485 ** overloaded or when the database connection closes.)^
  4486 ** ^The destructor is also invoked if the call to
  4487 ** sqlite3_create_function_v2() fails.
  4488 ** ^When the destructor callback of the tenth parameter is invoked, it
  4489 ** is passed a single argument which is a copy of the application data 
  4490 ** pointer which was the fifth parameter to sqlite3_create_function_v2().
  4491 **
  4492 ** ^It is permitted to register multiple implementations of the same
  4493 ** functions with the same name but with either differing numbers of
  4494 ** arguments or differing preferred text encodings.  ^SQLite will use
  4495 ** the implementation that most closely matches the way in which the
  4496 ** SQL function is used.  ^A function implementation with a non-negative
  4497 ** nArg parameter is a better match than a function implementation with
  4498 ** a negative nArg.  ^A function where the preferred text encoding
  4499 ** matches the database encoding is a better
  4500 ** match than a function where the encoding is different.  
  4501 ** ^A function where the encoding difference is between UTF16le and UTF16be
  4502 ** is a closer match than a function where the encoding difference is
  4503 ** between UTF8 and UTF16.
  4504 **
  4505 ** ^Built-in functions may be overloaded by new application-defined functions.
  4506 **
  4507 ** ^An application-defined function is permitted to call other
  4508 ** SQLite interfaces.  However, such calls must not
  4509 ** close the database connection nor finalize or reset the prepared
  4510 ** statement in which the function is running.
  4511 */
  4512 SQLITE_API int sqlite3_create_function(
  4513   sqlite3 *db,
  4514   const char *zFunctionName,
  4515   int nArg,
  4516   int eTextRep,
  4517   void *pApp,
  4518   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4519   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4520   void (*xFinal)(sqlite3_context*)
  4521 );
  4522 SQLITE_API int sqlite3_create_function16(
  4523   sqlite3 *db,
  4524   const void *zFunctionName,
  4525   int nArg,
  4526   int eTextRep,
  4527   void *pApp,
  4528   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4529   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4530   void (*xFinal)(sqlite3_context*)
  4531 );
  4532 SQLITE_API int sqlite3_create_function_v2(
  4533   sqlite3 *db,
  4534   const char *zFunctionName,
  4535   int nArg,
  4536   int eTextRep,
  4537   void *pApp,
  4538   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4539   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4540   void (*xFinal)(sqlite3_context*),
  4541   void(*xDestroy)(void*)
  4542 );
  4543 
  4544 /*
  4545 ** CAPI3REF: Text Encodings
  4546 **
  4547 ** These constant define integer codes that represent the various
  4548 ** text encodings supported by SQLite.
  4549 */
  4550 #define SQLITE_UTF8           1    /* IMP: R-37514-35566 */
  4551 #define SQLITE_UTF16LE        2    /* IMP: R-03371-37637 */
  4552 #define SQLITE_UTF16BE        3    /* IMP: R-51971-34154 */
  4553 #define SQLITE_UTF16          4    /* Use native byte order */
  4554 #define SQLITE_ANY            5    /* Deprecated */
  4555 #define SQLITE_UTF16_ALIGNED  8    /* sqlite3_create_collation only */
  4556 
  4557 /*
  4558 ** CAPI3REF: Function Flags
  4559 **
  4560 ** These constants may be ORed together with the 
  4561 ** [SQLITE_UTF8 | preferred text encoding] as the fourth argument
  4562 ** to [sqlite3_create_function()], [sqlite3_create_function16()], or
  4563 ** [sqlite3_create_function_v2()].
  4564 */
  4565 #define SQLITE_DETERMINISTIC    0x800
  4566 
  4567 /*
  4568 ** CAPI3REF: Deprecated Functions
  4569 ** DEPRECATED
  4570 **
  4571 ** These functions are [deprecated].  In order to maintain
  4572 ** backwards compatibility with older code, these functions continue 
  4573 ** to be supported.  However, new applications should avoid
  4574 ** the use of these functions.  To encourage programmers to avoid
  4575 ** these functions, we will not explain what they do.
  4576 */
  4577 #ifndef SQLITE_OMIT_DEPRECATED
  4578 SQLITE_API SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*);
  4579 SQLITE_API SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*);
  4580 SQLITE_API SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);
  4581 SQLITE_API SQLITE_DEPRECATED int sqlite3_global_recover(void);
  4582 SQLITE_API SQLITE_DEPRECATED void sqlite3_thread_cleanup(void);
  4583 SQLITE_API SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),
  4584                       void*,sqlite3_int64);
  4585 #endif
  4586 
  4587 /*
  4588 ** CAPI3REF: Obtaining SQL Values
  4589 ** METHOD: sqlite3_value
  4590 **
  4591 ** The C-language implementation of SQL functions and aggregates uses
  4592 ** this set of interface routines to access the parameter values on
  4593 ** the function or aggregate.  
  4594 **
  4595 ** The xFunc (for scalar functions) or xStep (for aggregates) parameters
  4596 ** to [sqlite3_create_function()] and [sqlite3_create_function16()]
  4597 ** define callbacks that implement the SQL functions and aggregates.
  4598 ** The 3rd parameter to these callbacks is an array of pointers to
  4599 ** [protected sqlite3_value] objects.  There is one [sqlite3_value] object for
  4600 ** each parameter to the SQL function.  These routines are used to
  4601 ** extract values from the [sqlite3_value] objects.
  4602 **
  4603 ** These routines work only with [protected sqlite3_value] objects.
  4604 ** Any attempt to use these routines on an [unprotected sqlite3_value]
  4605 ** object results in undefined behavior.
  4606 **
  4607 ** ^These routines work just like the corresponding [column access functions]
  4608 ** except that these routines take a single [protected sqlite3_value] object
  4609 ** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
  4610 **
  4611 ** ^The sqlite3_value_text16() interface extracts a UTF-16 string
  4612 ** in the native byte-order of the host machine.  ^The
  4613 ** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
  4614 ** extract UTF-16 strings as big-endian and little-endian respectively.
  4615 **
  4616 ** ^(The sqlite3_value_numeric_type() interface attempts to apply
  4617 ** numeric affinity to the value.  This means that an attempt is
  4618 ** made to convert the value to an integer or floating point.  If
  4619 ** such a conversion is possible without loss of information (in other
  4620 ** words, if the value is a string that looks like a number)
  4621 ** then the conversion is performed.  Otherwise no conversion occurs.
  4622 ** The [SQLITE_INTEGER | datatype] after conversion is returned.)^
  4623 **
  4624 ** Please pay particular attention to the fact that the pointer returned
  4625 ** from [sqlite3_value_blob()], [sqlite3_value_text()], or
  4626 ** [sqlite3_value_text16()] can be invalidated by a subsequent call to
  4627 ** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
  4628 ** or [sqlite3_value_text16()].
  4629 **
  4630 ** These routines must be called from the same thread as
  4631 ** the SQL function that supplied the [sqlite3_value*] parameters.
  4632 */
  4633 SQLITE_API const void *sqlite3_value_blob(sqlite3_value*);
  4634 SQLITE_API int sqlite3_value_bytes(sqlite3_value*);
  4635 SQLITE_API int sqlite3_value_bytes16(sqlite3_value*);
  4636 SQLITE_API double sqlite3_value_double(sqlite3_value*);
  4637 SQLITE_API int sqlite3_value_int(sqlite3_value*);
  4638 SQLITE_API sqlite3_int64 sqlite3_value_int64(sqlite3_value*);
  4639 SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value*);
  4640 SQLITE_API const void *sqlite3_value_text16(sqlite3_value*);
  4641 SQLITE_API const void *sqlite3_value_text16le(sqlite3_value*);
  4642 SQLITE_API const void *sqlite3_value_text16be(sqlite3_value*);
  4643 SQLITE_API int sqlite3_value_type(sqlite3_value*);
  4644 SQLITE_API int sqlite3_value_numeric_type(sqlite3_value*);
  4645 
  4646 /*
  4647 ** CAPI3REF: Finding The Subtype Of SQL Values
  4648 ** METHOD: sqlite3_value
  4649 **
  4650 ** The sqlite3_value_subtype(V) function returns the subtype for
  4651 ** an [application-defined SQL function] argument V.  The subtype
  4652 ** information can be used to pass a limited amount of context from
  4653 ** one SQL function to another.  Use the [sqlite3_result_subtype()]
  4654 ** routine to set the subtype for the return value of an SQL function.
  4655 **
  4656 ** SQLite makes no use of subtype itself.  It merely passes the subtype
  4657 ** from the result of one [application-defined SQL function] into the
  4658 ** input of another.
  4659 */
  4660 SQLITE_API unsigned int sqlite3_value_subtype(sqlite3_value*);
  4661 
  4662 /*
  4663 ** CAPI3REF: Copy And Free SQL Values
  4664 ** METHOD: sqlite3_value
  4665 **
  4666 ** ^The sqlite3_value_dup(V) interface makes a copy of the [sqlite3_value]
  4667 ** object D and returns a pointer to that copy.  ^The [sqlite3_value] returned
  4668 ** is a [protected sqlite3_value] object even if the input is not.
  4669 ** ^The sqlite3_value_dup(V) interface returns NULL if V is NULL or if a
  4670 ** memory allocation fails.
  4671 **
  4672 ** ^The sqlite3_value_free(V) interface frees an [sqlite3_value] object
  4673 ** previously obtained from [sqlite3_value_dup()].  ^If V is a NULL pointer
  4674 ** then sqlite3_value_free(V) is a harmless no-op.
  4675 */
  4676 SQLITE_API sqlite3_value *sqlite3_value_dup(const sqlite3_value*);
  4677 SQLITE_API void sqlite3_value_free(sqlite3_value*);
  4678 
  4679 /*
  4680 ** CAPI3REF: Obtain Aggregate Function Context
  4681 ** METHOD: sqlite3_context
  4682 **
  4683 ** Implementations of aggregate SQL functions use this
  4684 ** routine to allocate memory for storing their state.
  4685 **
  4686 ** ^The first time the sqlite3_aggregate_context(C,N) routine is called 
  4687 ** for a particular aggregate function, SQLite
  4688 ** allocates N of memory, zeroes out that memory, and returns a pointer
  4689 ** to the new memory. ^On second and subsequent calls to
  4690 ** sqlite3_aggregate_context() for the same aggregate function instance,
  4691 ** the same buffer is returned.  Sqlite3_aggregate_context() is normally
  4692 ** called once for each invocation of the xStep callback and then one
  4693 ** last time when the xFinal callback is invoked.  ^(When no rows match
  4694 ** an aggregate query, the xStep() callback of the aggregate function
  4695 ** implementation is never called and xFinal() is called exactly once.
  4696 ** In those cases, sqlite3_aggregate_context() might be called for the
  4697 ** first time from within xFinal().)^
  4698 **
  4699 ** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer 
  4700 ** when first called if N is less than or equal to zero or if a memory
  4701 ** allocate error occurs.
  4702 **
  4703 ** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is
  4704 ** determined by the N parameter on first successful call.  Changing the
  4705 ** value of N in subsequent call to sqlite3_aggregate_context() within
  4706 ** the same aggregate function instance will not resize the memory
  4707 ** allocation.)^  Within the xFinal callback, it is customary to set
  4708 ** N=0 in calls to sqlite3_aggregate_context(C,N) so that no 
  4709 ** pointless memory allocations occur.
  4710 **
  4711 ** ^SQLite automatically frees the memory allocated by 
  4712 ** sqlite3_aggregate_context() when the aggregate query concludes.
  4713 **
  4714 ** The first parameter must be a copy of the
  4715 ** [sqlite3_context | SQL function context] that is the first parameter
  4716 ** to the xStep or xFinal callback routine that implements the aggregate
  4717 ** function.
  4718 **
  4719 ** This routine must be called from the same thread in which
  4720 ** the aggregate SQL function is running.
  4721 */
  4722 SQLITE_API void *sqlite3_aggregate_context(sqlite3_context*, int nBytes);
  4723 
  4724 /*
  4725 ** CAPI3REF: User Data For Functions
  4726 ** METHOD: sqlite3_context
  4727 **
  4728 ** ^The sqlite3_user_data() interface returns a copy of
  4729 ** the pointer that was the pUserData parameter (the 5th parameter)
  4730 ** of the [sqlite3_create_function()]
  4731 ** and [sqlite3_create_function16()] routines that originally
  4732 ** registered the application defined function.
  4733 **
  4734 ** This routine must be called from the same thread in which
  4735 ** the application-defined function is running.
  4736 */
  4737 SQLITE_API void *sqlite3_user_data(sqlite3_context*);
  4738 
  4739 /*
  4740 ** CAPI3REF: Database Connection For Functions
  4741 ** METHOD: sqlite3_context
  4742 **
  4743 ** ^The sqlite3_context_db_handle() interface returns a copy of
  4744 ** the pointer to the [database connection] (the 1st parameter)
  4745 ** of the [sqlite3_create_function()]
  4746 ** and [sqlite3_create_function16()] routines that originally
  4747 ** registered the application defined function.
  4748 */
  4749 SQLITE_API sqlite3 *sqlite3_context_db_handle(sqlite3_context*);
  4750 
  4751 /*
  4752 ** CAPI3REF: Function Auxiliary Data
  4753 ** METHOD: sqlite3_context
  4754 **
  4755 ** These functions may be used by (non-aggregate) SQL functions to
  4756 ** associate metadata with argument values. If the same value is passed to
  4757 ** multiple invocations of the same SQL function during query execution, under
  4758 ** some circumstances the associated metadata may be preserved.  An example
  4759 ** of where this might be useful is in a regular-expression matching
  4760 ** function. The compiled version of the regular expression can be stored as
  4761 ** metadata associated with the pattern string.  
  4762 ** Then as long as the pattern string remains the same,
  4763 ** the compiled regular expression can be reused on multiple
  4764 ** invocations of the same function.
  4765 **
  4766 ** ^The sqlite3_get_auxdata(C,N) interface returns a pointer to the metadata
  4767 ** associated by the sqlite3_set_auxdata(C,N,P,X) function with the Nth argument
  4768 ** value to the application-defined function.  ^N is zero for the left-most
  4769 ** function argument.  ^If there is no metadata
  4770 ** associated with the function argument, the sqlite3_get_auxdata(C,N) interface
  4771 ** returns a NULL pointer.
  4772 **
  4773 ** ^The sqlite3_set_auxdata(C,N,P,X) interface saves P as metadata for the N-th
  4774 ** argument of the application-defined function.  ^Subsequent
  4775 ** calls to sqlite3_get_auxdata(C,N) return P from the most recent
  4776 ** sqlite3_set_auxdata(C,N,P,X) call if the metadata is still valid or
  4777 ** NULL if the metadata has been discarded.
  4778 ** ^After each call to sqlite3_set_auxdata(C,N,P,X) where X is not NULL,
  4779 ** SQLite will invoke the destructor function X with parameter P exactly
  4780 ** once, when the metadata is discarded.
  4781 ** SQLite is free to discard the metadata at any time, including: <ul>
  4782 ** <li> ^(when the corresponding function parameter changes)^, or
  4783 ** <li> ^(when [sqlite3_reset()] or [sqlite3_finalize()] is called for the
  4784 **      SQL statement)^, or
  4785 ** <li> ^(when sqlite3_set_auxdata() is invoked again on the same
  4786 **       parameter)^, or
  4787 ** <li> ^(during the original sqlite3_set_auxdata() call when a memory 
  4788 **      allocation error occurs.)^ </ul>
  4789 **
  4790 ** Note the last bullet in particular.  The destructor X in 
  4791 ** sqlite3_set_auxdata(C,N,P,X) might be called immediately, before the
  4792 ** sqlite3_set_auxdata() interface even returns.  Hence sqlite3_set_auxdata()
  4793 ** should be called near the end of the function implementation and the
  4794 ** function implementation should not make any use of P after
  4795 ** sqlite3_set_auxdata() has been called.
  4796 **
  4797 ** ^(In practice, metadata is preserved between function calls for
  4798 ** function parameters that are compile-time constants, including literal
  4799 ** values and [parameters] and expressions composed from the same.)^
  4800 **
  4801 ** The value of the N parameter to these interfaces should be non-negative.
  4802 ** Future enhancements may make use of negative N values to define new
  4803 ** kinds of function caching behavior.
  4804 **
  4805 ** These routines must be called from the same thread in which
  4806 ** the SQL function is running.
  4807 */
  4808 SQLITE_API void *sqlite3_get_auxdata(sqlite3_context*, int N);
  4809 SQLITE_API void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));
  4810 
  4811 
  4812 /*
  4813 ** CAPI3REF: Constants Defining Special Destructor Behavior
  4814 **
  4815 ** These are special values for the destructor that is passed in as the
  4816 ** final argument to routines like [sqlite3_result_blob()].  ^If the destructor
  4817 ** argument is SQLITE_STATIC, it means that the content pointer is constant
  4818 ** and will never change.  It does not need to be destroyed.  ^The
  4819 ** SQLITE_TRANSIENT value means that the content will likely change in
  4820 ** the near future and that SQLite should make its own private copy of
  4821 ** the content before returning.
  4822 **
  4823 ** The typedef is necessary to work around problems in certain
  4824 ** C++ compilers.
  4825 */
  4826 typedef void (*sqlite3_destructor_type)(void*);
  4827 #define SQLITE_STATIC      ((sqlite3_destructor_type)0)
  4828 #define SQLITE_TRANSIENT   ((sqlite3_destructor_type)-1)
  4829 
  4830 /*
  4831 ** CAPI3REF: Setting The Result Of An SQL Function
  4832 ** METHOD: sqlite3_context
  4833 **
  4834 ** These routines are used by the xFunc or xFinal callbacks that
  4835 ** implement SQL functions and aggregates.  See
  4836 ** [sqlite3_create_function()] and [sqlite3_create_function16()]
  4837 ** for additional information.
  4838 **
  4839 ** These functions work very much like the [parameter binding] family of
  4840 ** functions used to bind values to host parameters in prepared statements.
  4841 ** Refer to the [SQL parameter] documentation for additional information.
  4842 **
  4843 ** ^The sqlite3_result_blob() interface sets the result from
  4844 ** an application-defined function to be the BLOB whose content is pointed
  4845 ** to by the second parameter and which is N bytes long where N is the
  4846 ** third parameter.
  4847 **
  4848 ** ^The sqlite3_result_zeroblob(C,N) and sqlite3_result_zeroblob64(C,N)
  4849 ** interfaces set the result of the application-defined function to be
  4850 ** a BLOB containing all zero bytes and N bytes in size.
  4851 **
  4852 ** ^The sqlite3_result_double() interface sets the result from
  4853 ** an application-defined function to be a floating point value specified
  4854 ** by its 2nd argument.
  4855 **
  4856 ** ^The sqlite3_result_error() and sqlite3_result_error16() functions
  4857 ** cause the implemented SQL function to throw an exception.
  4858 ** ^SQLite uses the string pointed to by the
  4859 ** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
  4860 ** as the text of an error message.  ^SQLite interprets the error
  4861 ** message string from sqlite3_result_error() as UTF-8. ^SQLite
  4862 ** interprets the string from sqlite3_result_error16() as UTF-16 in native
  4863 ** byte order.  ^If the third parameter to sqlite3_result_error()
  4864 ** or sqlite3_result_error16() is negative then SQLite takes as the error
  4865 ** message all text up through the first zero character.
  4866 ** ^If the third parameter to sqlite3_result_error() or
  4867 ** sqlite3_result_error16() is non-negative then SQLite takes that many
  4868 ** bytes (not characters) from the 2nd parameter as the error message.
  4869 ** ^The sqlite3_result_error() and sqlite3_result_error16()
  4870 ** routines make a private copy of the error message text before
  4871 ** they return.  Hence, the calling function can deallocate or
  4872 ** modify the text after they return without harm.
  4873 ** ^The sqlite3_result_error_code() function changes the error code
  4874 ** returned by SQLite as a result of an error in a function.  ^By default,
  4875 ** the error code is SQLITE_ERROR.  ^A subsequent call to sqlite3_result_error()
  4876 ** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
  4877 **
  4878 ** ^The sqlite3_result_error_toobig() interface causes SQLite to throw an
  4879 ** error indicating that a string or BLOB is too long to represent.
  4880 **
  4881 ** ^The sqlite3_result_error_nomem() interface causes SQLite to throw an
  4882 ** error indicating that a memory allocation failed.
  4883 **
  4884 ** ^The sqlite3_result_int() interface sets the return value
  4885 ** of the application-defined function to be the 32-bit signed integer
  4886 ** value given in the 2nd argument.
  4887 ** ^The sqlite3_result_int64() interface sets the return value
  4888 ** of the application-defined function to be the 64-bit signed integer
  4889 ** value given in the 2nd argument.
  4890 **
  4891 ** ^The sqlite3_result_null() interface sets the return value
  4892 ** of the application-defined function to be NULL.
  4893 **
  4894 ** ^The sqlite3_result_text(), sqlite3_result_text16(),
  4895 ** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
  4896 ** set the return value of the application-defined function to be
  4897 ** a text string which is represented as UTF-8, UTF-16 native byte order,
  4898 ** UTF-16 little endian, or UTF-16 big endian, respectively.
  4899 ** ^The sqlite3_result_text64() interface sets the return value of an
  4900 ** application-defined function to be a text string in an encoding
  4901 ** specified by the fifth (and last) parameter, which must be one
  4902 ** of [SQLITE_UTF8], [SQLITE_UTF16], [SQLITE_UTF16BE], or [SQLITE_UTF16LE].
  4903 ** ^SQLite takes the text result from the application from
  4904 ** the 2nd parameter of the sqlite3_result_text* interfaces.
  4905 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
  4906 ** is negative, then SQLite takes result text from the 2nd parameter
  4907 ** through the first zero character.
  4908 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
  4909 ** is non-negative, then as many bytes (not characters) of the text
  4910 ** pointed to by the 2nd parameter are taken as the application-defined
  4911 ** function result.  If the 3rd parameter is non-negative, then it
  4912 ** must be the byte offset into the string where the NUL terminator would
  4913 ** appear if the string where NUL terminated.  If any NUL characters occur
  4914 ** in the string at a byte offset that is less than the value of the 3rd
  4915 ** parameter, then the resulting string will contain embedded NULs and the
  4916 ** result of expressions operating on strings with embedded NULs is undefined.
  4917 ** ^If the 4th parameter to the sqlite3_result_text* interfaces
  4918 ** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
  4919 ** function as the destructor on the text or BLOB result when it has
  4920 ** finished using that result.
  4921 ** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
  4922 ** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
  4923 ** assumes that the text or BLOB result is in constant space and does not
  4924 ** copy the content of the parameter nor call a destructor on the content
  4925 ** when it has finished using that result.
  4926 ** ^If the 4th parameter to the sqlite3_result_text* interfaces
  4927 ** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
  4928 ** then SQLite makes a copy of the result into space obtained from
  4929 ** from [sqlite3_malloc()] before it returns.
  4930 **
  4931 ** ^The sqlite3_result_value() interface sets the result of
  4932 ** the application-defined function to be a copy of the
  4933 ** [unprotected sqlite3_value] object specified by the 2nd parameter.  ^The
  4934 ** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
  4935 ** so that the [sqlite3_value] specified in the parameter may change or
  4936 ** be deallocated after sqlite3_result_value() returns without harm.
  4937 ** ^A [protected sqlite3_value] object may always be used where an
  4938 ** [unprotected sqlite3_value] object is required, so either
  4939 ** kind of [sqlite3_value] object can be used with this interface.
  4940 **
  4941 ** If these routines are called from within the different thread
  4942 ** than the one containing the application-defined function that received
  4943 ** the [sqlite3_context] pointer, the results are undefined.
  4944 */
  4945 SQLITE_API void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
  4946 SQLITE_API void sqlite3_result_blob64(sqlite3_context*,const void*,
  4947                            sqlite3_uint64,void(*)(void*));
  4948 SQLITE_API void sqlite3_result_double(sqlite3_context*, double);
  4949 SQLITE_API void sqlite3_result_error(sqlite3_context*, const char*, int);
  4950 SQLITE_API void sqlite3_result_error16(sqlite3_context*, const void*, int);
  4951 SQLITE_API void sqlite3_result_error_toobig(sqlite3_context*);
  4952 SQLITE_API void sqlite3_result_error_nomem(sqlite3_context*);
  4953 SQLITE_API void sqlite3_result_error_code(sqlite3_context*, int);
  4954 SQLITE_API void sqlite3_result_int(sqlite3_context*, int);
  4955 SQLITE_API void sqlite3_result_int64(sqlite3_context*, sqlite3_int64);
  4956 SQLITE_API void sqlite3_result_null(sqlite3_context*);
  4957 SQLITE_API void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
  4958 SQLITE_API void sqlite3_result_text64(sqlite3_context*, const char*,sqlite3_uint64,
  4959                            void(*)(void*), unsigned char encoding);
  4960 SQLITE_API void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
  4961 SQLITE_API void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
  4962 SQLITE_API void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
  4963 SQLITE_API void sqlite3_result_value(sqlite3_context*, sqlite3_value*);
  4964 SQLITE_API void sqlite3_result_zeroblob(sqlite3_context*, int n);
  4965 SQLITE_API int sqlite3_result_zeroblob64(sqlite3_context*, sqlite3_uint64 n);
  4966 
  4967 
  4968 /*
  4969 ** CAPI3REF: Setting The Subtype Of An SQL Function
  4970 ** METHOD: sqlite3_context
  4971 **
  4972 ** The sqlite3_result_subtype(C,T) function causes the subtype of
  4973 ** the result from the [application-defined SQL function] with 
  4974 ** [sqlite3_context] C to be the value T.  Only the lower 8 bits 
  4975 ** of the subtype T are preserved in current versions of SQLite;
  4976 ** higher order bits are discarded.
  4977 ** The number of subtype bytes preserved by SQLite might increase
  4978 ** in future releases of SQLite.
  4979 */
  4980 SQLITE_API void sqlite3_result_subtype(sqlite3_context*,unsigned int);
  4981 
  4982 /*
  4983 ** CAPI3REF: Define New Collating Sequences
  4984 ** METHOD: sqlite3
  4985 **
  4986 ** ^These functions add, remove, or modify a [collation] associated
  4987 ** with the [database connection] specified as the first argument.
  4988 **
  4989 ** ^The name of the collation is a UTF-8 string
  4990 ** for sqlite3_create_collation() and sqlite3_create_collation_v2()
  4991 ** and a UTF-16 string in native byte order for sqlite3_create_collation16().
  4992 ** ^Collation names that compare equal according to [sqlite3_strnicmp()] are
  4993 ** considered to be the same name.
  4994 **
  4995 ** ^(The third argument (eTextRep) must be one of the constants:
  4996 ** <ul>
  4997 ** <li> [SQLITE_UTF8],
  4998 ** <li> [SQLITE_UTF16LE],
  4999 ** <li> [SQLITE_UTF16BE],
  5000 ** <li> [SQLITE_UTF16], or
  5001 ** <li> [SQLITE_UTF16_ALIGNED].
  5002 ** </ul>)^
  5003 ** ^The eTextRep argument determines the encoding of strings passed
  5004 ** to the collating function callback, xCallback.
  5005 ** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep
  5006 ** force strings to be UTF16 with native byte order.
  5007 ** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin
  5008 ** on an even byte address.
  5009 **
  5010 ** ^The fourth argument, pArg, is an application data pointer that is passed
  5011 ** through as the first argument to the collating function callback.
  5012 **
  5013 ** ^The fifth argument, xCallback, is a pointer to the collating function.
  5014 ** ^Multiple collating functions can be registered using the same name but
  5015 ** with different eTextRep parameters and SQLite will use whichever
  5016 ** function requires the least amount of data transformation.
  5017 ** ^If the xCallback argument is NULL then the collating function is
  5018 ** deleted.  ^When all collating functions having the same name are deleted,
  5019 ** that collation is no longer usable.
  5020 **
  5021 ** ^The collating function callback is invoked with a copy of the pArg 
  5022 ** application data pointer and with two strings in the encoding specified
  5023 ** by the eTextRep argument.  The collating function must return an
  5024 ** integer that is negative, zero, or positive
  5025 ** if the first string is less than, equal to, or greater than the second,
  5026 ** respectively.  A collating function must always return the same answer
  5027 ** given the same inputs.  If two or more collating functions are registered
  5028 ** to the same collation name (using different eTextRep values) then all
  5029 ** must give an equivalent answer when invoked with equivalent strings.
  5030 ** The collating function must obey the following properties for all
  5031 ** strings A, B, and C:
  5032 **
  5033 ** <ol>
  5034 ** <li> If A==B then B==A.
  5035 ** <li> If A==B and B==C then A==C.
  5036 ** <li> If A&lt;B THEN B&gt;A.
  5037 ** <li> If A&lt;B and B&lt;C then A&lt;C.
  5038 ** </ol>
  5039 **
  5040 ** If a collating function fails any of the above constraints and that
  5041 ** collating function is  registered and used, then the behavior of SQLite
  5042 ** is undefined.
  5043 **
  5044 ** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation()
  5045 ** with the addition that the xDestroy callback is invoked on pArg when
  5046 ** the collating function is deleted.
  5047 ** ^Collating functions are deleted when they are overridden by later
  5048 ** calls to the collation creation functions or when the
  5049 ** [database connection] is closed using [sqlite3_close()].
  5050 **
  5051 ** ^The xDestroy callback is <u>not</u> called if the 
  5052 ** sqlite3_create_collation_v2() function fails.  Applications that invoke
  5053 ** sqlite3_create_collation_v2() with a non-NULL xDestroy argument should 
  5054 ** check the return code and dispose of the application data pointer
  5055 ** themselves rather than expecting SQLite to deal with it for them.
  5056 ** This is different from every other SQLite interface.  The inconsistency 
  5057 ** is unfortunate but cannot be changed without breaking backwards 
  5058 ** compatibility.
  5059 **
  5060 ** See also:  [sqlite3_collation_needed()] and [sqlite3_collation_needed16()].
  5061 */
  5062 SQLITE_API int sqlite3_create_collation(
  5063   sqlite3*, 
  5064   const char *zName, 
  5065   int eTextRep, 
  5066   void *pArg,
  5067   int(*xCompare)(void*,int,const void*,int,const void*)
  5068 );
  5069 SQLITE_API int sqlite3_create_collation_v2(
  5070   sqlite3*, 
  5071   const char *zName, 
  5072   int eTextRep, 
  5073   void *pArg,
  5074   int(*xCompare)(void*,int,const void*,int,const void*),
  5075   void(*xDestroy)(void*)
  5076 );
  5077 SQLITE_API int sqlite3_create_collation16(
  5078   sqlite3*, 
  5079   const void *zName,
  5080   int eTextRep, 
  5081   void *pArg,
  5082   int(*xCompare)(void*,int,const void*,int,const void*)
  5083 );
  5084 
  5085 /*
  5086 ** CAPI3REF: Collation Needed Callbacks
  5087 ** METHOD: sqlite3
  5088 **
  5089 ** ^To avoid having to register all collation sequences before a database
  5090 ** can be used, a single callback function may be registered with the
  5091 ** [database connection] to be invoked whenever an undefined collation
  5092 ** sequence is required.
  5093 **
  5094 ** ^If the function is registered using the sqlite3_collation_needed() API,
  5095 ** then it is passed the names of undefined collation sequences as strings
  5096 ** encoded in UTF-8. ^If sqlite3_collation_needed16() is used,
  5097 ** the names are passed as UTF-16 in machine native byte order.
  5098 ** ^A call to either function replaces the existing collation-needed callback.
  5099 **
  5100 ** ^(When the callback is invoked, the first argument passed is a copy
  5101 ** of the second argument to sqlite3_collation_needed() or
  5102 ** sqlite3_collation_needed16().  The second argument is the database
  5103 ** connection.  The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
  5104 ** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
  5105 ** sequence function required.  The fourth parameter is the name of the
  5106 ** required collation sequence.)^
  5107 **
  5108 ** The callback function should register the desired collation using
  5109 ** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
  5110 ** [sqlite3_create_collation_v2()].
  5111 */
  5112 SQLITE_API int sqlite3_collation_needed(
  5113   sqlite3*, 
  5114   void*, 
  5115   void(*)(void*,sqlite3*,int eTextRep,const char*)
  5116 );
  5117 SQLITE_API int sqlite3_collation_needed16(
  5118   sqlite3*, 
  5119   void*,
  5120   void(*)(void*,sqlite3*,int eTextRep,const void*)
  5121 );
  5122 
  5123 #ifdef SQLITE_HAS_CODEC
  5124 /*
  5125 ** Specify the key for an encrypted database.  This routine should be
  5126 ** called right after sqlite3_open().
  5127 **
  5128 ** The code to implement this API is not available in the public release
  5129 ** of SQLite.
  5130 */
  5131 SQLITE_API int sqlite3_key(
  5132   sqlite3 *db,                   /* Database to be rekeyed */
  5133   const void *pKey, int nKey     /* The key */
  5134 );
  5135 SQLITE_API int sqlite3_key_v2(
  5136   sqlite3 *db,                   /* Database to be rekeyed */
  5137   const char *zDbName,           /* Name of the database */
  5138   const void *pKey, int nKey     /* The key */
  5139 );
  5140 
  5141 /*
  5142 ** Change the key on an open database.  If the current database is not
  5143 ** encrypted, this routine will encrypt it.  If pNew==0 or nNew==0, the
  5144 ** database is decrypted.
  5145 **
  5146 ** The code to implement this API is not available in the public release
  5147 ** of SQLite.
  5148 */
  5149 SQLITE_API int sqlite3_rekey(
  5150   sqlite3 *db,                   /* Database to be rekeyed */
  5151   const void *pKey, int nKey     /* The new key */
  5152 );
  5153 SQLITE_API int sqlite3_rekey_v2(
  5154   sqlite3 *db,                   /* Database to be rekeyed */
  5155   const char *zDbName,           /* Name of the database */
  5156   const void *pKey, int nKey     /* The new key */
  5157 );
  5158 
  5159 /*
  5160 ** Specify the activation key for a SEE database.  Unless 
  5161 ** activated, none of the SEE routines will work.
  5162 */
  5163 SQLITE_API void sqlite3_activate_see(
  5164   const char *zPassPhrase        /* Activation phrase */
  5165 );
  5166 #endif
  5167 
  5168 #ifdef SQLITE_ENABLE_CEROD
  5169 /*
  5170 ** Specify the activation key for a CEROD database.  Unless 
  5171 ** activated, none of the CEROD routines will work.
  5172 */
  5173 SQLITE_API void sqlite3_activate_cerod(
  5174   const char *zPassPhrase        /* Activation phrase */
  5175 );
  5176 #endif
  5177 
  5178 /*
  5179 ** CAPI3REF: Suspend Execution For A Short Time
  5180 **
  5181 ** The sqlite3_sleep() function causes the current thread to suspend execution
  5182 ** for at least a number of milliseconds specified in its parameter.
  5183 **
  5184 ** If the operating system does not support sleep requests with
  5185 ** millisecond time resolution, then the time will be rounded up to
  5186 ** the nearest second. The number of milliseconds of sleep actually
  5187 ** requested from the operating system is returned.
  5188 **
  5189 ** ^SQLite implements this interface by calling the xSleep()
  5190 ** method of the default [sqlite3_vfs] object.  If the xSleep() method
  5191 ** of the default VFS is not implemented correctly, or not implemented at
  5192 ** all, then the behavior of sqlite3_sleep() may deviate from the description
  5193 ** in the previous paragraphs.
  5194 */
  5195 SQLITE_API int sqlite3_sleep(int);
  5196 
  5197 /*
  5198 ** CAPI3REF: Name Of The Folder Holding Temporary Files
  5199 **
  5200 ** ^(If this global variable is made to point to a string which is
  5201 ** the name of a folder (a.k.a. directory), then all temporary files
  5202 ** created by SQLite when using a built-in [sqlite3_vfs | VFS]
  5203 ** will be placed in that directory.)^  ^If this variable
  5204 ** is a NULL pointer, then SQLite performs a search for an appropriate
  5205 ** temporary file directory.
  5206 **
  5207 ** Applications are strongly discouraged from using this global variable.
  5208 ** It is required to set a temporary folder on Windows Runtime (WinRT).
  5209 ** But for all other platforms, it is highly recommended that applications
  5210 ** neither read nor write this variable.  This global variable is a relic
  5211 ** that exists for backwards compatibility of legacy applications and should
  5212 ** be avoided in new projects.
  5213 **
  5214 ** It is not safe to read or modify this variable in more than one
  5215 ** thread at a time.  It is not safe to read or modify this variable
  5216 ** if a [database connection] is being used at the same time in a separate
  5217 ** thread.
  5218 ** It is intended that this variable be set once
  5219 ** as part of process initialization and before any SQLite interface
  5220 ** routines have been called and that this variable remain unchanged
  5221 ** thereafter.
  5222 **
  5223 ** ^The [temp_store_directory pragma] may modify this variable and cause
  5224 ** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
  5225 ** the [temp_store_directory pragma] always assumes that any string
  5226 ** that this variable points to is held in memory obtained from 
  5227 ** [sqlite3_malloc] and the pragma may attempt to free that memory
  5228 ** using [sqlite3_free].
  5229 ** Hence, if this variable is modified directly, either it should be
  5230 ** made NULL or made to point to memory obtained from [sqlite3_malloc]
  5231 ** or else the use of the [temp_store_directory pragma] should be avoided.
  5232 ** Except when requested by the [temp_store_directory pragma], SQLite
  5233 ** does not free the memory that sqlite3_temp_directory points to.  If
  5234 ** the application wants that memory to be freed, it must do
  5235 ** so itself, taking care to only do so after all [database connection]
  5236 ** objects have been destroyed.
  5237 **
  5238 ** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
  5239 ** prior to calling [sqlite3_open] or [sqlite3_open_v2].  Otherwise, various
  5240 ** features that require the use of temporary files may fail.  Here is an
  5241 ** example of how to do this using C++ with the Windows Runtime:
  5242 **
  5243 ** <blockquote><pre>
  5244 ** LPCWSTR zPath = Windows::Storage::ApplicationData::Current->
  5245 ** &nbsp;     TemporaryFolder->Path->Data();
  5246 ** char zPathBuf&#91;MAX_PATH + 1&#93;;
  5247 ** memset(zPathBuf, 0, sizeof(zPathBuf));
  5248 ** WideCharToMultiByte(CP_UTF8, 0, zPath, -1, zPathBuf, sizeof(zPathBuf),
  5249 ** &nbsp;     NULL, NULL);
  5250 ** sqlite3_temp_directory = sqlite3_mprintf("%s", zPathBuf);
  5251 ** </pre></blockquote>
  5252 */
  5253 SQLITE_API SQLITE_EXTERN char *sqlite3_temp_directory;
  5254 
  5255 /*
  5256 ** CAPI3REF: Name Of The Folder Holding Database Files
  5257 **
  5258 ** ^(If this global variable is made to point to a string which is
  5259 ** the name of a folder (a.k.a. directory), then all database files
  5260 ** specified with a relative pathname and created or accessed by
  5261 ** SQLite when using a built-in windows [sqlite3_vfs | VFS] will be assumed
  5262 ** to be relative to that directory.)^ ^If this variable is a NULL
  5263 ** pointer, then SQLite assumes that all database files specified
  5264 ** with a relative pathname are relative to the current directory
  5265 ** for the process.  Only the windows VFS makes use of this global
  5266 ** variable; it is ignored by the unix VFS.
  5267 **
  5268 ** Changing the value of this variable while a database connection is
  5269 ** open can result in a corrupt database.
  5270 **
  5271 ** It is not safe to read or modify this variable in more than one
  5272 ** thread at a time.  It is not safe to read or modify this variable
  5273 ** if a [database connection] is being used at the same time in a separate
  5274 ** thread.
  5275 ** It is intended that this variable be set once
  5276 ** as part of process initialization and before any SQLite interface
  5277 ** routines have been called and that this variable remain unchanged
  5278 ** thereafter.
  5279 **
  5280 ** ^The [data_store_directory pragma] may modify this variable and cause
  5281 ** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
  5282 ** the [data_store_directory pragma] always assumes that any string
  5283 ** that this variable points to is held in memory obtained from 
  5284 ** [sqlite3_malloc] and the pragma may attempt to free that memory
  5285 ** using [sqlite3_free].
  5286 ** Hence, if this variable is modified directly, either it should be
  5287 ** made NULL or made to point to memory obtained from [sqlite3_malloc]
  5288 ** or else the use of the [data_store_directory pragma] should be avoided.
  5289 */
  5290 SQLITE_API SQLITE_EXTERN char *sqlite3_data_directory;
  5291 
  5292 /*
  5293 ** CAPI3REF: Test For Auto-Commit Mode
  5294 ** KEYWORDS: {autocommit mode}
  5295 ** METHOD: sqlite3
  5296 **
  5297 ** ^The sqlite3_get_autocommit() interface returns non-zero or
  5298 ** zero if the given database connection is or is not in autocommit mode,
  5299 ** respectively.  ^Autocommit mode is on by default.
  5300 ** ^Autocommit mode is disabled by a [BEGIN] statement.
  5301 ** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
  5302 **
  5303 ** If certain kinds of errors occur on a statement within a multi-statement
  5304 ** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
  5305 ** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the
  5306 ** transaction might be rolled back automatically.  The only way to
  5307 ** find out whether SQLite automatically rolled back the transaction after
  5308 ** an error is to use this function.
  5309 **
  5310 ** If another thread changes the autocommit status of the database
  5311 ** connection while this routine is running, then the return value
  5312 ** is undefined.
  5313 */
  5314 SQLITE_API int sqlite3_get_autocommit(sqlite3*);
  5315 
  5316 /*
  5317 ** CAPI3REF: Find The Database Handle Of A Prepared Statement
  5318 ** METHOD: sqlite3_stmt
  5319 **
  5320 ** ^The sqlite3_db_handle interface returns the [database connection] handle
  5321 ** to which a [prepared statement] belongs.  ^The [database connection]
  5322 ** returned by sqlite3_db_handle is the same [database connection]
  5323 ** that was the first argument
  5324 ** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
  5325 ** create the statement in the first place.
  5326 */
  5327 SQLITE_API sqlite3 *sqlite3_db_handle(sqlite3_stmt*);
  5328 
  5329 /*
  5330 ** CAPI3REF: Return The Filename For A Database Connection
  5331 ** METHOD: sqlite3
  5332 **
  5333 ** ^The sqlite3_db_filename(D,N) interface returns a pointer to a filename
  5334 ** associated with database N of connection D.  ^The main database file
  5335 ** has the name "main".  If there is no attached database N on the database
  5336 ** connection D, or if database N is a temporary or in-memory database, then
  5337 ** a NULL pointer is returned.
  5338 **
  5339 ** ^The filename returned by this function is the output of the
  5340 ** xFullPathname method of the [VFS].  ^In other words, the filename
  5341 ** will be an absolute pathname, even if the filename used
  5342 ** to open the database originally was a URI or relative pathname.
  5343 */
  5344 SQLITE_API const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName);
  5345 
  5346 /*
  5347 ** CAPI3REF: Determine if a database is read-only
  5348 ** METHOD: sqlite3
  5349 **
  5350 ** ^The sqlite3_db_readonly(D,N) interface returns 1 if the database N
  5351 ** of connection D is read-only, 0 if it is read/write, or -1 if N is not
  5352 ** the name of a database on connection D.
  5353 */
  5354 SQLITE_API int sqlite3_db_readonly(sqlite3 *db, const char *zDbName);
  5355 
  5356 /*
  5357 ** CAPI3REF: Find the next prepared statement
  5358 ** METHOD: sqlite3
  5359 **
  5360 ** ^This interface returns a pointer to the next [prepared statement] after
  5361 ** pStmt associated with the [database connection] pDb.  ^If pStmt is NULL
  5362 ** then this interface returns a pointer to the first prepared statement
  5363 ** associated with the database connection pDb.  ^If no prepared statement
  5364 ** satisfies the conditions of this routine, it returns NULL.
  5365 **
  5366 ** The [database connection] pointer D in a call to
  5367 ** [sqlite3_next_stmt(D,S)] must refer to an open database
  5368 ** connection and in particular must not be a NULL pointer.
  5369 */
  5370 SQLITE_API sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);
  5371 
  5372 /*
  5373 ** CAPI3REF: Commit And Rollback Notification Callbacks
  5374 ** METHOD: sqlite3
  5375 **
  5376 ** ^The sqlite3_commit_hook() interface registers a callback
  5377 ** function to be invoked whenever a transaction is [COMMIT | committed].
  5378 ** ^Any callback set by a previous call to sqlite3_commit_hook()
  5379 ** for the same database connection is overridden.
  5380 ** ^The sqlite3_rollback_hook() interface registers a callback
  5381 ** function to be invoked whenever a transaction is [ROLLBACK | rolled back].
  5382 ** ^Any callback set by a previous call to sqlite3_rollback_hook()
  5383 ** for the same database connection is overridden.
  5384 ** ^The pArg argument is passed through to the callback.
  5385 ** ^If the callback on a commit hook function returns non-zero,
  5386 ** then the commit is converted into a rollback.
  5387 **
  5388 ** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions
  5389 ** return the P argument from the previous call of the same function
  5390 ** on the same [database connection] D, or NULL for
  5391 ** the first call for each function on D.
  5392 **
  5393 ** The commit and rollback hook callbacks are not reentrant.
  5394 ** The callback implementation must not do anything that will modify
  5395 ** the database connection that invoked the callback.  Any actions
  5396 ** to modify the database connection must be deferred until after the
  5397 ** completion of the [sqlite3_step()] call that triggered the commit
  5398 ** or rollback hook in the first place.
  5399 ** Note that running any other SQL statements, including SELECT statements,
  5400 ** or merely calling [sqlite3_prepare_v2()] and [sqlite3_step()] will modify
  5401 ** the database connections for the meaning of "modify" in this paragraph.
  5402 **
  5403 ** ^Registering a NULL function disables the callback.
  5404 **
  5405 ** ^When the commit hook callback routine returns zero, the [COMMIT]
  5406 ** operation is allowed to continue normally.  ^If the commit hook
  5407 ** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].
  5408 ** ^The rollback hook is invoked on a rollback that results from a commit
  5409 ** hook returning non-zero, just as it would be with any other rollback.
  5410 **
  5411 ** ^For the purposes of this API, a transaction is said to have been
  5412 ** rolled back if an explicit "ROLLBACK" statement is executed, or
  5413 ** an error or constraint causes an implicit rollback to occur.
  5414 ** ^The rollback callback is not invoked if a transaction is
  5415 ** automatically rolled back because the database connection is closed.
  5416 **
  5417 ** See also the [sqlite3_update_hook()] interface.
  5418 */
  5419 SQLITE_API void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
  5420 SQLITE_API void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
  5421 
  5422 /*
  5423 ** CAPI3REF: Data Change Notification Callbacks
  5424 ** METHOD: sqlite3
  5425 **
  5426 ** ^The sqlite3_update_hook() interface registers a callback function
  5427 ** with the [database connection] identified by the first argument
  5428 ** to be invoked whenever a row is updated, inserted or deleted in
  5429 ** a [rowid table].
  5430 ** ^Any callback set by a previous call to this function
  5431 ** for the same database connection is overridden.
  5432 **
  5433 ** ^The second argument is a pointer to the function to invoke when a
  5434 ** row is updated, inserted or deleted in a rowid table.
  5435 ** ^The first argument to the callback is a copy of the third argument
  5436 ** to sqlite3_update_hook().
  5437 ** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
  5438 ** or [SQLITE_UPDATE], depending on the operation that caused the callback
  5439 ** to be invoked.
  5440 ** ^The third and fourth arguments to the callback contain pointers to the
  5441 ** database and table name containing the affected row.
  5442 ** ^The final callback parameter is the [rowid] of the row.
  5443 ** ^In the case of an update, this is the [rowid] after the update takes place.
  5444 **
  5445 ** ^(The update hook is not invoked when internal system tables are
  5446 ** modified (i.e. sqlite_master and sqlite_sequence).)^
  5447 ** ^The update hook is not invoked when [WITHOUT ROWID] tables are modified.
  5448 **
  5449 ** ^In the current implementation, the update hook
  5450 ** is not invoked when conflicting rows are deleted because of an
  5451 ** [ON CONFLICT | ON CONFLICT REPLACE] clause.  ^Nor is the update hook
  5452 ** invoked when rows are deleted using the [truncate optimization].
  5453 ** The exceptions defined in this paragraph might change in a future
  5454 ** release of SQLite.
  5455 **
  5456 ** The update hook implementation must not do anything that will modify
  5457 ** the database connection that invoked the update hook.  Any actions
  5458 ** to modify the database connection must be deferred until after the
  5459 ** completion of the [sqlite3_step()] call that triggered the update hook.
  5460 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  5461 ** database connections for the meaning of "modify" in this paragraph.
  5462 **
  5463 ** ^The sqlite3_update_hook(D,C,P) function
  5464 ** returns the P argument from the previous call
  5465 ** on the same [database connection] D, or NULL for
  5466 ** the first call on D.
  5467 **
  5468 ** See also the [sqlite3_commit_hook()], [sqlite3_rollback_hook()],
  5469 ** and [sqlite3_preupdate_hook()] interfaces.
  5470 */
  5471 SQLITE_API void *sqlite3_update_hook(
  5472   sqlite3*, 
  5473   void(*)(void *,int ,char const *,char const *,sqlite3_int64),
  5474   void*
  5475 );
  5476 
  5477 /*
  5478 ** CAPI3REF: Enable Or Disable Shared Pager Cache
  5479 **
  5480 ** ^(This routine enables or disables the sharing of the database cache
  5481 ** and schema data structures between [database connection | connections]
  5482 ** to the same database. Sharing is enabled if the argument is true
  5483 ** and disabled if the argument is false.)^
  5484 **
  5485 ** ^Cache sharing is enabled and disabled for an entire process.
  5486 ** This is a change as of SQLite [version 3.5.0] ([dateof:3.5.0]). 
  5487 ** In prior versions of SQLite,
  5488 ** sharing was enabled or disabled for each thread separately.
  5489 **
  5490 ** ^(The cache sharing mode set by this interface effects all subsequent
  5491 ** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
  5492 ** Existing database connections continue use the sharing mode
  5493 ** that was in effect at the time they were opened.)^
  5494 **
  5495 ** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
  5496 ** successfully.  An [error code] is returned otherwise.)^
  5497 **
  5498 ** ^Shared cache is disabled by default. But this might change in
  5499 ** future releases of SQLite.  Applications that care about shared
  5500 ** cache setting should set it explicitly.
  5501 **
  5502 ** Note: This method is disabled on MacOS X 10.7 and iOS version 5.0
  5503 ** and will always return SQLITE_MISUSE. On those systems, 
  5504 ** shared cache mode should be enabled per-database connection via 
  5505 ** [sqlite3_open_v2()] with [SQLITE_OPEN_SHAREDCACHE].
  5506 **
  5507 ** This interface is threadsafe on processors where writing a
  5508 ** 32-bit integer is atomic.
  5509 **
  5510 ** See Also:  [SQLite Shared-Cache Mode]
  5511 */
  5512 SQLITE_API int sqlite3_enable_shared_cache(int);
  5513 
  5514 /*
  5515 ** CAPI3REF: Attempt To Free Heap Memory
  5516 **
  5517 ** ^The sqlite3_release_memory() interface attempts to free N bytes
  5518 ** of heap memory by deallocating non-essential memory allocations
  5519 ** held by the database library.   Memory used to cache database
  5520 ** pages to improve performance is an example of non-essential memory.
  5521 ** ^sqlite3_release_memory() returns the number of bytes actually freed,
  5522 ** which might be more or less than the amount requested.
  5523 ** ^The sqlite3_release_memory() routine is a no-op returning zero
  5524 ** if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT].
  5525 **
  5526 ** See also: [sqlite3_db_release_memory()]
  5527 */
  5528 SQLITE_API int sqlite3_release_memory(int);
  5529 
  5530 /*
  5531 ** CAPI3REF: Free Memory Used By A Database Connection
  5532 ** METHOD: sqlite3
  5533 **
  5534 ** ^The sqlite3_db_release_memory(D) interface attempts to free as much heap
  5535 ** memory as possible from database connection D. Unlike the
  5536 ** [sqlite3_release_memory()] interface, this interface is in effect even
  5537 ** when the [SQLITE_ENABLE_MEMORY_MANAGEMENT] compile-time option is
  5538 ** omitted.
  5539 **
  5540 ** See also: [sqlite3_release_memory()]
  5541 */
  5542 SQLITE_API int sqlite3_db_release_memory(sqlite3*);
  5543 
  5544 /*
  5545 ** CAPI3REF: Impose A Limit On Heap Size
  5546 **
  5547 ** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the
  5548 ** soft limit on the amount of heap memory that may be allocated by SQLite.
  5549 ** ^SQLite strives to keep heap memory utilization below the soft heap
  5550 ** limit by reducing the number of pages held in the page cache
  5551 ** as heap memory usages approaches the limit.
  5552 ** ^The soft heap limit is "soft" because even though SQLite strives to stay
  5553 ** below the limit, it will exceed the limit rather than generate
  5554 ** an [SQLITE_NOMEM] error.  In other words, the soft heap limit 
  5555 ** is advisory only.
  5556 **
  5557 ** ^The return value from sqlite3_soft_heap_limit64() is the size of
  5558 ** the soft heap limit prior to the call, or negative in the case of an
  5559 ** error.  ^If the argument N is negative
  5560 ** then no change is made to the soft heap limit.  Hence, the current
  5561 ** size of the soft heap limit can be determined by invoking
  5562 ** sqlite3_soft_heap_limit64() with a negative argument.
  5563 **
  5564 ** ^If the argument N is zero then the soft heap limit is disabled.
  5565 **
  5566 ** ^(The soft heap limit is not enforced in the current implementation
  5567 ** if one or more of following conditions are true:
  5568 **
  5569 ** <ul>
  5570 ** <li> The soft heap limit is set to zero.
  5571 ** <li> Memory accounting is disabled using a combination of the
  5572 **      [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
  5573 **      the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
  5574 ** <li> An alternative page cache implementation is specified using
  5575 **      [sqlite3_config]([SQLITE_CONFIG_PCACHE2],...).
  5576 ** <li> The page cache allocates from its own memory pool supplied
  5577 **      by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than
  5578 **      from the heap.
  5579 ** </ul>)^
  5580 **
  5581 ** Beginning with SQLite [version 3.7.3] ([dateof:3.7.3]), 
  5582 ** the soft heap limit is enforced
  5583 ** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]
  5584 ** compile-time option is invoked.  With [SQLITE_ENABLE_MEMORY_MANAGEMENT],
  5585 ** the soft heap limit is enforced on every memory allocation.  Without
  5586 ** [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced
  5587 ** when memory is allocated by the page cache.  Testing suggests that because
  5588 ** the page cache is the predominate memory user in SQLite, most
  5589 ** applications will achieve adequate soft heap limit enforcement without
  5590 ** the use of [SQLITE_ENABLE_MEMORY_MANAGEMENT].
  5591 **
  5592 ** The circumstances under which SQLite will enforce the soft heap limit may
  5593 ** changes in future releases of SQLite.
  5594 */
  5595 SQLITE_API sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 N);
  5596 
  5597 /*
  5598 ** CAPI3REF: Deprecated Soft Heap Limit Interface
  5599 ** DEPRECATED
  5600 **
  5601 ** This is a deprecated version of the [sqlite3_soft_heap_limit64()]
  5602 ** interface.  This routine is provided for historical compatibility
  5603 ** only.  All new applications should use the
  5604 ** [sqlite3_soft_heap_limit64()] interface rather than this one.
  5605 */
  5606 SQLITE_API SQLITE_DEPRECATED void sqlite3_soft_heap_limit(int N);
  5607 
  5608 
  5609 /*
  5610 ** CAPI3REF: Extract Metadata About A Column Of A Table
  5611 ** METHOD: sqlite3
  5612 **
  5613 ** ^(The sqlite3_table_column_metadata(X,D,T,C,....) routine returns
  5614 ** information about column C of table T in database D
  5615 ** on [database connection] X.)^  ^The sqlite3_table_column_metadata()
  5616 ** interface returns SQLITE_OK and fills in the non-NULL pointers in
  5617 ** the final five arguments with appropriate values if the specified
  5618 ** column exists.  ^The sqlite3_table_column_metadata() interface returns
  5619 ** SQLITE_ERROR and if the specified column does not exist.
  5620 ** ^If the column-name parameter to sqlite3_table_column_metadata() is a
  5621 ** NULL pointer, then this routine simply checks for the existence of the
  5622 ** table and returns SQLITE_OK if the table exists and SQLITE_ERROR if it
  5623 ** does not.
  5624 **
  5625 ** ^The column is identified by the second, third and fourth parameters to
  5626 ** this function. ^(The second parameter is either the name of the database
  5627 ** (i.e. "main", "temp", or an attached database) containing the specified
  5628 ** table or NULL.)^ ^If it is NULL, then all attached databases are searched
  5629 ** for the table using the same algorithm used by the database engine to
  5630 ** resolve unqualified table references.
  5631 **
  5632 ** ^The third and fourth parameters to this function are the table and column
  5633 ** name of the desired column, respectively.
  5634 **
  5635 ** ^Metadata is returned by writing to the memory locations passed as the 5th
  5636 ** and subsequent parameters to this function. ^Any of these arguments may be
  5637 ** NULL, in which case the corresponding element of metadata is omitted.
  5638 **
  5639 ** ^(<blockquote>
  5640 ** <table border="1">
  5641 ** <tr><th> Parameter <th> Output<br>Type <th>  Description
  5642 **
  5643 ** <tr><td> 5th <td> const char* <td> Data type
  5644 ** <tr><td> 6th <td> const char* <td> Name of default collation sequence
  5645 ** <tr><td> 7th <td> int         <td> True if column has a NOT NULL constraint
  5646 ** <tr><td> 8th <td> int         <td> True if column is part of the PRIMARY KEY
  5647 ** <tr><td> 9th <td> int         <td> True if column is [AUTOINCREMENT]
  5648 ** </table>
  5649 ** </blockquote>)^
  5650 **
  5651 ** ^The memory pointed to by the character pointers returned for the
  5652 ** declaration type and collation sequence is valid until the next
  5653 ** call to any SQLite API function.
  5654 **
  5655 ** ^If the specified table is actually a view, an [error code] is returned.
  5656 **
  5657 ** ^If the specified column is "rowid", "oid" or "_rowid_" and the table 
  5658 ** is not a [WITHOUT ROWID] table and an
  5659 ** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
  5660 ** parameters are set for the explicitly declared column. ^(If there is no
  5661 ** [INTEGER PRIMARY KEY] column, then the outputs
  5662 ** for the [rowid] are set as follows:
  5663 **
  5664 ** <pre>
  5665 **     data type: "INTEGER"
  5666 **     collation sequence: "BINARY"
  5667 **     not null: 0
  5668 **     primary key: 1
  5669 **     auto increment: 0
  5670 ** </pre>)^
  5671 **
  5672 ** ^This function causes all database schemas to be read from disk and
  5673 ** parsed, if that has not already been done, and returns an error if
  5674 ** any errors are encountered while loading the schema.
  5675 */
  5676 SQLITE_API int sqlite3_table_column_metadata(
  5677   sqlite3 *db,                /* Connection handle */
  5678   const char *zDbName,        /* Database name or NULL */
  5679   const char *zTableName,     /* Table name */
  5680   const char *zColumnName,    /* Column name */
  5681   char const **pzDataType,    /* OUTPUT: Declared data type */
  5682   char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
  5683   int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
  5684   int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
  5685   int *pAutoinc               /* OUTPUT: True if column is auto-increment */
  5686 );
  5687 
  5688 /*
  5689 ** CAPI3REF: Load An Extension
  5690 ** METHOD: sqlite3
  5691 **
  5692 ** ^This interface loads an SQLite extension library from the named file.
  5693 **
  5694 ** ^The sqlite3_load_extension() interface attempts to load an
  5695 ** [SQLite extension] library contained in the file zFile.  If
  5696 ** the file cannot be loaded directly, attempts are made to load
  5697 ** with various operating-system specific extensions added.
  5698 ** So for example, if "samplelib" cannot be loaded, then names like
  5699 ** "samplelib.so" or "samplelib.dylib" or "samplelib.dll" might
  5700 ** be tried also.
  5701 **
  5702 ** ^The entry point is zProc.
  5703 ** ^(zProc may be 0, in which case SQLite will try to come up with an
  5704 ** entry point name on its own.  It first tries "sqlite3_extension_init".
  5705 ** If that does not work, it constructs a name "sqlite3_X_init" where the
  5706 ** X is consists of the lower-case equivalent of all ASCII alphabetic
  5707 ** characters in the filename from the last "/" to the first following
  5708 ** "." and omitting any initial "lib".)^
  5709 ** ^The sqlite3_load_extension() interface returns
  5710 ** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
  5711 ** ^If an error occurs and pzErrMsg is not 0, then the
  5712 ** [sqlite3_load_extension()] interface shall attempt to
  5713 ** fill *pzErrMsg with error message text stored in memory
  5714 ** obtained from [sqlite3_malloc()]. The calling function
  5715 ** should free this memory by calling [sqlite3_free()].
  5716 **
  5717 ** ^Extension loading must be enabled using
  5718 ** [sqlite3_enable_load_extension()] or
  5719 ** [sqlite3_db_config](db,[SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION],1,NULL)
  5720 ** prior to calling this API,
  5721 ** otherwise an error will be returned.
  5722 **
  5723 ** <b>Security warning:</b> It is recommended that the 
  5724 ** [SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION] method be used to enable only this
  5725 ** interface.  The use of the [sqlite3_enable_load_extension()] interface
  5726 ** should be avoided.  This will keep the SQL function [load_extension()]
  5727 ** disabled and prevent SQL injections from giving attackers
  5728 ** access to extension loading capabilities.
  5729 **
  5730 ** See also the [load_extension() SQL function].
  5731 */
  5732 SQLITE_API int sqlite3_load_extension(
  5733   sqlite3 *db,          /* Load the extension into this database connection */
  5734   const char *zFile,    /* Name of the shared library containing extension */
  5735   const char *zProc,    /* Entry point.  Derived from zFile if 0 */
  5736   char **pzErrMsg       /* Put error message here if not 0 */
  5737 );
  5738 
  5739 /*
  5740 ** CAPI3REF: Enable Or Disable Extension Loading
  5741 ** METHOD: sqlite3
  5742 **
  5743 ** ^So as not to open security holes in older applications that are
  5744 ** unprepared to deal with [extension loading], and as a means of disabling
  5745 ** [extension loading] while evaluating user-entered SQL, the following API
  5746 ** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
  5747 **
  5748 ** ^Extension loading is off by default.
  5749 ** ^Call the sqlite3_enable_load_extension() routine with onoff==1
  5750 ** to turn extension loading on and call it with onoff==0 to turn
  5751 ** it back off again.
  5752 **
  5753 ** ^This interface enables or disables both the C-API
  5754 ** [sqlite3_load_extension()] and the SQL function [load_extension()].
  5755 ** ^(Use [sqlite3_db_config](db,[SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION],..)
  5756 ** to enable or disable only the C-API.)^
  5757 **
  5758 ** <b>Security warning:</b> It is recommended that extension loading
  5759 ** be disabled using the [SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION] method
  5760 ** rather than this interface, so the [load_extension()] SQL function
  5761 ** remains disabled. This will prevent SQL injections from giving attackers
  5762 ** access to extension loading capabilities.
  5763 */
  5764 SQLITE_API int sqlite3_enable_load_extension(sqlite3 *db, int onoff);
  5765 
  5766 /*
  5767 ** CAPI3REF: Automatically Load Statically Linked Extensions
  5768 **
  5769 ** ^This interface causes the xEntryPoint() function to be invoked for
  5770 ** each new [database connection] that is created.  The idea here is that
  5771 ** xEntryPoint() is the entry point for a statically linked [SQLite extension]
  5772 ** that is to be automatically loaded into all new database connections.
  5773 **
  5774 ** ^(Even though the function prototype shows that xEntryPoint() takes
  5775 ** no arguments and returns void, SQLite invokes xEntryPoint() with three
  5776 ** arguments and expects an integer result as if the signature of the
  5777 ** entry point where as follows:
  5778 **
  5779 ** <blockquote><pre>
  5780 ** &nbsp;  int xEntryPoint(
  5781 ** &nbsp;    sqlite3 *db,
  5782 ** &nbsp;    const char **pzErrMsg,
  5783 ** &nbsp;    const struct sqlite3_api_routines *pThunk
  5784 ** &nbsp;  );
  5785 ** </pre></blockquote>)^
  5786 **
  5787 ** If the xEntryPoint routine encounters an error, it should make *pzErrMsg
  5788 ** point to an appropriate error message (obtained from [sqlite3_mprintf()])
  5789 ** and return an appropriate [error code].  ^SQLite ensures that *pzErrMsg
  5790 ** is NULL before calling the xEntryPoint().  ^SQLite will invoke
  5791 ** [sqlite3_free()] on *pzErrMsg after xEntryPoint() returns.  ^If any
  5792 ** xEntryPoint() returns an error, the [sqlite3_open()], [sqlite3_open16()],
  5793 ** or [sqlite3_open_v2()] call that provoked the xEntryPoint() will fail.
  5794 **
  5795 ** ^Calling sqlite3_auto_extension(X) with an entry point X that is already
  5796 ** on the list of automatic extensions is a harmless no-op. ^No entry point
  5797 ** will be called more than once for each database connection that is opened.
  5798 **
  5799 ** See also: [sqlite3_reset_auto_extension()]
  5800 ** and [sqlite3_cancel_auto_extension()]
  5801 */
  5802 SQLITE_API int sqlite3_auto_extension(void(*xEntryPoint)(void));
  5803 
  5804 /*
  5805 ** CAPI3REF: Cancel Automatic Extension Loading
  5806 **
  5807 ** ^The [sqlite3_cancel_auto_extension(X)] interface unregisters the
  5808 ** initialization routine X that was registered using a prior call to
  5809 ** [sqlite3_auto_extension(X)].  ^The [sqlite3_cancel_auto_extension(X)]
  5810 ** routine returns 1 if initialization routine X was successfully 
  5811 ** unregistered and it returns 0 if X was not on the list of initialization
  5812 ** routines.
  5813 */
  5814 SQLITE_API int sqlite3_cancel_auto_extension(void(*xEntryPoint)(void));
  5815 
  5816 /*
  5817 ** CAPI3REF: Reset Automatic Extension Loading
  5818 **
  5819 ** ^This interface disables all automatic extensions previously
  5820 ** registered using [sqlite3_auto_extension()].
  5821 */
  5822 SQLITE_API void sqlite3_reset_auto_extension(void);
  5823 
  5824 /*
  5825 ** The interface to the virtual-table mechanism is currently considered
  5826 ** to be experimental.  The interface might change in incompatible ways.
  5827 ** If this is a problem for you, do not use the interface at this time.
  5828 **
  5829 ** When the virtual-table mechanism stabilizes, we will declare the
  5830 ** interface fixed, support it indefinitely, and remove this comment.
  5831 */
  5832 
  5833 /*
  5834 ** Structures used by the virtual table interface
  5835 */
  5836 typedef struct sqlite3_vtab sqlite3_vtab;
  5837 typedef struct sqlite3_index_info sqlite3_index_info;
  5838 typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
  5839 typedef struct sqlite3_module sqlite3_module;
  5840 
  5841 /*
  5842 ** CAPI3REF: Virtual Table Object
  5843 ** KEYWORDS: sqlite3_module {virtual table module}
  5844 **
  5845 ** This structure, sometimes called a "virtual table module", 
  5846 ** defines the implementation of a [virtual tables].  
  5847 ** This structure consists mostly of methods for the module.
  5848 **
  5849 ** ^A virtual table module is created by filling in a persistent
  5850 ** instance of this structure and passing a pointer to that instance
  5851 ** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].
  5852 ** ^The registration remains valid until it is replaced by a different
  5853 ** module or until the [database connection] closes.  The content
  5854 ** of this structure must not change while it is registered with
  5855 ** any database connection.
  5856 */
  5857 struct sqlite3_module {
  5858   int iVersion;
  5859   int (*xCreate)(sqlite3*, void *pAux,
  5860                int argc, const char *const*argv,
  5861                sqlite3_vtab **ppVTab, char**);
  5862   int (*xConnect)(sqlite3*, void *pAux,
  5863                int argc, const char *const*argv,
  5864                sqlite3_vtab **ppVTab, char**);
  5865   int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
  5866   int (*xDisconnect)(sqlite3_vtab *pVTab);
  5867   int (*xDestroy)(sqlite3_vtab *pVTab);
  5868   int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
  5869   int (*xClose)(sqlite3_vtab_cursor*);
  5870   int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
  5871                 int argc, sqlite3_value **argv);
  5872   int (*xNext)(sqlite3_vtab_cursor*);
  5873   int (*xEof)(sqlite3_vtab_cursor*);
  5874   int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int);
  5875   int (*xRowid)(sqlite3_vtab_cursor*, sqlite3_int64 *pRowid);
  5876   int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite3_int64 *);
  5877   int (*xBegin)(sqlite3_vtab *pVTab);
  5878   int (*xSync)(sqlite3_vtab *pVTab);
  5879   int (*xCommit)(sqlite3_vtab *pVTab);
  5880   int (*xRollback)(sqlite3_vtab *pVTab);
  5881   int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName,
  5882                        void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
  5883                        void **ppArg);
  5884   int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
  5885   /* The methods above are in version 1 of the sqlite_module object. Those 
  5886   ** below are for version 2 and greater. */
  5887   int (*xSavepoint)(sqlite3_vtab *pVTab, int);
  5888   int (*xRelease)(sqlite3_vtab *pVTab, int);
  5889   int (*xRollbackTo)(sqlite3_vtab *pVTab, int);
  5890 };
  5891 
  5892 /*
  5893 ** CAPI3REF: Virtual Table Indexing Information
  5894 ** KEYWORDS: sqlite3_index_info
  5895 **
  5896 ** The sqlite3_index_info structure and its substructures is used as part
  5897 ** of the [virtual table] interface to
  5898 ** pass information into and receive the reply from the [xBestIndex]
  5899 ** method of a [virtual table module].  The fields under **Inputs** are the
  5900 ** inputs to xBestIndex and are read-only.  xBestIndex inserts its
  5901 ** results into the **Outputs** fields.
  5902 **
  5903 ** ^(The aConstraint[] array records WHERE clause constraints of the form:
  5904 **
  5905 ** <blockquote>column OP expr</blockquote>
  5906 **
  5907 ** where OP is =, &lt;, &lt;=, &gt;, or &gt;=.)^  ^(The particular operator is
  5908 ** stored in aConstraint[].op using one of the
  5909 ** [SQLITE_INDEX_CONSTRAINT_EQ | SQLITE_INDEX_CONSTRAINT_ values].)^
  5910 ** ^(The index of the column is stored in
  5911 ** aConstraint[].iColumn.)^  ^(aConstraint[].usable is TRUE if the
  5912 ** expr on the right-hand side can be evaluated (and thus the constraint
  5913 ** is usable) and false if it cannot.)^
  5914 **
  5915 ** ^The optimizer automatically inverts terms of the form "expr OP column"
  5916 ** and makes other simplifications to the WHERE clause in an attempt to
  5917 ** get as many WHERE clause terms into the form shown above as possible.
  5918 ** ^The aConstraint[] array only reports WHERE clause terms that are
  5919 ** relevant to the particular virtual table being queried.
  5920 **
  5921 ** ^Information about the ORDER BY clause is stored in aOrderBy[].
  5922 ** ^Each term of aOrderBy records a column of the ORDER BY clause.
  5923 **
  5924 ** The colUsed field indicates which columns of the virtual table may be
  5925 ** required by the current scan. Virtual table columns are numbered from
  5926 ** zero in the order in which they appear within the CREATE TABLE statement
  5927 ** passed to sqlite3_declare_vtab(). For the first 63 columns (columns 0-62),
  5928 ** the corresponding bit is set within the colUsed mask if the column may be
  5929 ** required by SQLite. If the table has at least 64 columns and any column
  5930 ** to the right of the first 63 is required, then bit 63 of colUsed is also
  5931 ** set. In other words, column iCol may be required if the expression
  5932 ** (colUsed & ((sqlite3_uint64)1 << (iCol>=63 ? 63 : iCol))) evaluates to 
  5933 ** non-zero.
  5934 **
  5935 ** The [xBestIndex] method must fill aConstraintUsage[] with information
  5936 ** about what parameters to pass to xFilter.  ^If argvIndex>0 then
  5937 ** the right-hand side of the corresponding aConstraint[] is evaluated
  5938 ** and becomes the argvIndex-th entry in argv.  ^(If aConstraintUsage[].omit
  5939 ** is true, then the constraint is assumed to be fully handled by the
  5940 ** virtual table and is not checked again by SQLite.)^
  5941 **
  5942 ** ^The idxNum and idxPtr values are recorded and passed into the
  5943 ** [xFilter] method.
  5944 ** ^[sqlite3_free()] is used to free idxPtr if and only if
  5945 ** needToFreeIdxPtr is true.
  5946 **
  5947 ** ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in
  5948 ** the correct order to satisfy the ORDER BY clause so that no separate
  5949 ** sorting step is required.
  5950 **
  5951 ** ^The estimatedCost value is an estimate of the cost of a particular
  5952 ** strategy. A cost of N indicates that the cost of the strategy is similar
  5953 ** to a linear scan of an SQLite table with N rows. A cost of log(N) 
  5954 ** indicates that the expense of the operation is similar to that of a
  5955 ** binary search on a unique indexed field of an SQLite table with N rows.
  5956 **
  5957 ** ^The estimatedRows value is an estimate of the number of rows that
  5958 ** will be returned by the strategy.
  5959 **
  5960 ** The xBestIndex method may optionally populate the idxFlags field with a 
  5961 ** mask of SQLITE_INDEX_SCAN_* flags. Currently there is only one such flag -
  5962 ** SQLITE_INDEX_SCAN_UNIQUE. If the xBestIndex method sets this flag, SQLite
  5963 ** assumes that the strategy may visit at most one row. 
  5964 **
  5965 ** Additionally, if xBestIndex sets the SQLITE_INDEX_SCAN_UNIQUE flag, then
  5966 ** SQLite also assumes that if a call to the xUpdate() method is made as
  5967 ** part of the same statement to delete or update a virtual table row and the
  5968 ** implementation returns SQLITE_CONSTRAINT, then there is no need to rollback
  5969 ** any database changes. In other words, if the xUpdate() returns
  5970 ** SQLITE_CONSTRAINT, the database contents must be exactly as they were
  5971 ** before xUpdate was called. By contrast, if SQLITE_INDEX_SCAN_UNIQUE is not
  5972 ** set and xUpdate returns SQLITE_CONSTRAINT, any database changes made by
  5973 ** the xUpdate method are automatically rolled back by SQLite.
  5974 **
  5975 ** IMPORTANT: The estimatedRows field was added to the sqlite3_index_info
  5976 ** structure for SQLite [version 3.8.2] ([dateof:3.8.2]). 
  5977 ** If a virtual table extension is
  5978 ** used with an SQLite version earlier than 3.8.2, the results of attempting 
  5979 ** to read or write the estimatedRows field are undefined (but are likely 
  5980 ** to included crashing the application). The estimatedRows field should
  5981 ** therefore only be used if [sqlite3_libversion_number()] returns a
  5982 ** value greater than or equal to 3008002. Similarly, the idxFlags field
  5983 ** was added for [version 3.9.0] ([dateof:3.9.0]). 
  5984 ** It may therefore only be used if
  5985 ** sqlite3_libversion_number() returns a value greater than or equal to
  5986 ** 3009000.
  5987 */
  5988 struct sqlite3_index_info {
  5989   /* Inputs */
  5990   int nConstraint;           /* Number of entries in aConstraint */
  5991   struct sqlite3_index_constraint {
  5992      int iColumn;              /* Column constrained.  -1 for ROWID */
  5993      unsigned char op;         /* Constraint operator */
  5994      unsigned char usable;     /* True if this constraint is usable */
  5995      int iTermOffset;          /* Used internally - xBestIndex should ignore */
  5996   } *aConstraint;            /* Table of WHERE clause constraints */
  5997   int nOrderBy;              /* Number of terms in the ORDER BY clause */
  5998   struct sqlite3_index_orderby {
  5999      int iColumn;              /* Column number */
  6000      unsigned char desc;       /* True for DESC.  False for ASC. */
  6001   } *aOrderBy;               /* The ORDER BY clause */
  6002   /* Outputs */
  6003   struct sqlite3_index_constraint_usage {
  6004     int argvIndex;           /* if >0, constraint is part of argv to xFilter */
  6005     unsigned char omit;      /* Do not code a test for this constraint */