src/sqlite3.h
author Volker Birk <vb@pep-project.org>
Thu, 26 Mar 2015 15:30:21 +0100
changeset 130 507895068f83
child 491 d32c60ada438
permissions -rw-r--r--
modifications for Windoze
     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 suppose 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 ** Add the ability to override 'extern'
    47 */
    48 #ifndef SQLITE_EXTERN
    49 # define SQLITE_EXTERN extern
    50 #endif
    51 
    52 #ifndef SQLITE_API
    53 # define SQLITE_API
    54 #endif
    55 
    56 
    57 /*
    58 ** These no-op macros are used in front of interfaces to mark those
    59 ** interfaces as either deprecated or experimental.  New applications
    60 ** should not use deprecated interfaces - they are support for backwards
    61 ** compatibility only.  Application writers should be aware that
    62 ** experimental interfaces are subject to change in point releases.
    63 **
    64 ** These macros used to resolve to various kinds of compiler magic that
    65 ** would generate warning messages when they were used.  But that
    66 ** compiler magic ended up generating such a flurry of bug reports
    67 ** that we have taken it all out and gone back to using simple
    68 ** noop macros.
    69 */
    70 #define SQLITE_DEPRECATED
    71 #define SQLITE_EXPERIMENTAL
    72 
    73 /*
    74 ** Ensure these symbols were not defined by some previous header file.
    75 */
    76 #ifdef SQLITE_VERSION
    77 # undef SQLITE_VERSION
    78 #endif
    79 #ifdef SQLITE_VERSION_NUMBER
    80 # undef SQLITE_VERSION_NUMBER
    81 #endif
    82 
    83 /*
    84 ** CAPI3REF: Compile-Time Library Version Numbers
    85 **
    86 ** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header
    87 ** evaluates to a string literal that is the SQLite version in the
    88 ** format "X.Y.Z" where X is the major version number (always 3 for
    89 ** SQLite3) and Y is the minor version number and Z is the release number.)^
    90 ** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer
    91 ** with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z are the same
    92 ** numbers used in [SQLITE_VERSION].)^
    93 ** The SQLITE_VERSION_NUMBER for any given release of SQLite will also
    94 ** be larger than the release from which it is derived.  Either Y will
    95 ** be held constant and Z will be incremented or else Y will be incremented
    96 ** and Z will be reset to zero.
    97 **
    98 ** Since version 3.6.18, SQLite source code has been stored in the
    99 ** <a href="http://www.fossil-scm.org/">Fossil configuration management
   100 ** system</a>.  ^The SQLITE_SOURCE_ID macro evaluates to
   101 ** a string which identifies a particular check-in of SQLite
   102 ** within its configuration management system.  ^The SQLITE_SOURCE_ID
   103 ** string contains the date and time of the check-in (UTC) and an SHA1
   104 ** hash of the entire source tree.
   105 **
   106 ** See also: [sqlite3_libversion()],
   107 ** [sqlite3_libversion_number()], [sqlite3_sourceid()],
   108 ** [sqlite_version()] and [sqlite_source_id()].
   109 */
   110 #define SQLITE_VERSION        "3.8.6"
   111 #define SQLITE_VERSION_NUMBER 3008006
   112 #define SQLITE_SOURCE_ID      "2014-08-15 11:46:33 9491ba7d738528f168657adb43a198238abde19e"
   113 
   114 /*
   115 ** CAPI3REF: Run-Time Library Version Numbers
   116 ** KEYWORDS: sqlite3_version, sqlite3_sourceid
   117 **
   118 ** These interfaces provide the same information as the [SQLITE_VERSION],
   119 ** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
   120 ** but are associated with the library instead of the header file.  ^(Cautious
   121 ** programmers might include assert() statements in their application to
   122 ** verify that values returned by these interfaces match the macros in
   123 ** the header, and thus insure that the application is
   124 ** compiled with matching library and header files.
   125 **
   126 ** <blockquote><pre>
   127 ** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
   128 ** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );
   129 ** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
   130 ** </pre></blockquote>)^
   131 **
   132 ** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
   133 ** macro.  ^The sqlite3_libversion() function returns a pointer to the
   134 ** to the sqlite3_version[] string constant.  The sqlite3_libversion()
   135 ** function is provided for use in DLLs since DLL users usually do not have
   136 ** direct access to string constants within the DLL.  ^The
   137 ** sqlite3_libversion_number() function returns an integer equal to
   138 ** [SQLITE_VERSION_NUMBER].  ^The sqlite3_sourceid() function returns 
   139 ** a pointer to a string constant whose value is the same as the 
   140 ** [SQLITE_SOURCE_ID] C preprocessor macro.
   141 **
   142 ** See also: [sqlite_version()] and [sqlite_source_id()].
   143 */
   144 SQLITE_API SQLITE_EXTERN const char sqlite3_version[];
   145 SQLITE_API const char *sqlite3_libversion(void);
   146 SQLITE_API const char *sqlite3_sourceid(void);
   147 SQLITE_API int sqlite3_libversion_number(void);
   148 
   149 /*
   150 ** CAPI3REF: Run-Time Library Compilation Options Diagnostics
   151 **
   152 ** ^The sqlite3_compileoption_used() function returns 0 or 1 
   153 ** indicating whether the specified option was defined at 
   154 ** compile time.  ^The SQLITE_ prefix may be omitted from the 
   155 ** option name passed to sqlite3_compileoption_used().  
   156 **
   157 ** ^The sqlite3_compileoption_get() function allows iterating
   158 ** over the list of options that were defined at compile time by
   159 ** returning the N-th compile time option string.  ^If N is out of range,
   160 ** sqlite3_compileoption_get() returns a NULL pointer.  ^The SQLITE_ 
   161 ** prefix is omitted from any strings returned by 
   162 ** sqlite3_compileoption_get().
   163 **
   164 ** ^Support for the diagnostic functions sqlite3_compileoption_used()
   165 ** and sqlite3_compileoption_get() may be omitted by specifying the 
   166 ** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
   167 **
   168 ** See also: SQL functions [sqlite_compileoption_used()] and
   169 ** [sqlite_compileoption_get()] and the [compile_options pragma].
   170 */
   171 #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
   172 SQLITE_API int sqlite3_compileoption_used(const char *zOptName);
   173 SQLITE_API const char *sqlite3_compileoption_get(int N);
   174 #endif
   175 
   176 /*
   177 ** CAPI3REF: Test To See If The Library Is Threadsafe
   178 **
   179 ** ^The sqlite3_threadsafe() function returns zero if and only if
   180 ** SQLite was compiled with mutexing code omitted due to the
   181 ** [SQLITE_THREADSAFE] compile-time option being set to 0.
   182 **
   183 ** SQLite can be compiled with or without mutexes.  When
   184 ** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes
   185 ** are enabled and SQLite is threadsafe.  When the
   186 ** [SQLITE_THREADSAFE] macro is 0, 
   187 ** the mutexes are omitted.  Without the mutexes, it is not safe
   188 ** to use SQLite concurrently from more than one thread.
   189 **
   190 ** Enabling mutexes incurs a measurable performance penalty.
   191 ** So if speed is of utmost importance, it makes sense to disable
   192 ** the mutexes.  But for maximum safety, mutexes should be enabled.
   193 ** ^The default behavior is for mutexes to be enabled.
   194 **
   195 ** This interface can be used by an application to make sure that the
   196 ** version of SQLite that it is linking against was compiled with
   197 ** the desired setting of the [SQLITE_THREADSAFE] macro.
   198 **
   199 ** This interface only reports on the compile-time mutex setting
   200 ** of the [SQLITE_THREADSAFE] flag.  If SQLite is compiled with
   201 ** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but
   202 ** can be fully or partially disabled using a call to [sqlite3_config()]
   203 ** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],
   204 ** or [SQLITE_CONFIG_MUTEX].  ^(The return value of the
   205 ** sqlite3_threadsafe() function shows only the compile-time setting of
   206 ** thread safety, not any run-time changes to that setting made by
   207 ** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()
   208 ** is unchanged by calls to sqlite3_config().)^
   209 **
   210 ** See the [threading mode] documentation for additional information.
   211 */
   212 SQLITE_API int sqlite3_threadsafe(void);
   213 
   214 /*
   215 ** CAPI3REF: Database Connection Handle
   216 ** KEYWORDS: {database connection} {database connections}
   217 **
   218 ** Each open SQLite database is represented by a pointer to an instance of
   219 ** the opaque structure named "sqlite3".  It is useful to think of an sqlite3
   220 ** pointer as an object.  The [sqlite3_open()], [sqlite3_open16()], and
   221 ** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
   222 ** and [sqlite3_close_v2()] are its destructors.  There are many other
   223 ** interfaces (such as
   224 ** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
   225 ** [sqlite3_busy_timeout()] to name but three) that are methods on an
   226 ** sqlite3 object.
   227 */
   228 typedef struct sqlite3 sqlite3;
   229 
   230 /*
   231 ** CAPI3REF: 64-Bit Integer Types
   232 ** KEYWORDS: sqlite_int64 sqlite_uint64
   233 **
   234 ** Because there is no cross-platform way to specify 64-bit integer types
   235 ** SQLite includes typedefs for 64-bit signed and unsigned integers.
   236 **
   237 ** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
   238 ** The sqlite_int64 and sqlite_uint64 types are supported for backwards
   239 ** compatibility only.
   240 **
   241 ** ^The sqlite3_int64 and sqlite_int64 types can store integer values
   242 ** between -9223372036854775808 and +9223372036854775807 inclusive.  ^The
   243 ** sqlite3_uint64 and sqlite_uint64 types can store integer values 
   244 ** between 0 and +18446744073709551615 inclusive.
   245 */
   246 #ifdef SQLITE_INT64_TYPE
   247   typedef SQLITE_INT64_TYPE sqlite_int64;
   248   typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
   249 #elif defined(_MSC_VER) || defined(__BORLANDC__)
   250   typedef __int64 sqlite_int64;
   251   typedef unsigned __int64 sqlite_uint64;
   252 #else
   253   typedef long long int sqlite_int64;
   254   typedef unsigned long long int sqlite_uint64;
   255 #endif
   256 typedef sqlite_int64 sqlite3_int64;
   257 typedef sqlite_uint64 sqlite3_uint64;
   258 
   259 /*
   260 ** If compiling for a processor that lacks floating point support,
   261 ** substitute integer for floating-point.
   262 */
   263 #ifdef SQLITE_OMIT_FLOATING_POINT
   264 # define double sqlite3_int64
   265 #endif
   266 
   267 /*
   268 ** CAPI3REF: Closing A Database Connection
   269 **
   270 ** ^The sqlite3_close() and sqlite3_close_v2() routines are destructors
   271 ** for the [sqlite3] object.
   272 ** ^Calls to sqlite3_close() and sqlite3_close_v2() return [SQLITE_OK] if
   273 ** the [sqlite3] object is successfully destroyed and all associated
   274 ** resources are deallocated.
   275 **
   276 ** ^If the database connection is associated with unfinalized prepared
   277 ** statements or unfinished sqlite3_backup objects then sqlite3_close()
   278 ** will leave the database connection open and return [SQLITE_BUSY].
   279 ** ^If sqlite3_close_v2() is called with unfinalized prepared statements
   280 ** and/or unfinished sqlite3_backups, then the database connection becomes
   281 ** an unusable "zombie" which will automatically be deallocated when the
   282 ** last prepared statement is finalized or the last sqlite3_backup is
   283 ** finished.  The sqlite3_close_v2() interface is intended for use with
   284 ** host languages that are garbage collected, and where the order in which
   285 ** destructors are called is arbitrary.
   286 **
   287 ** Applications should [sqlite3_finalize | finalize] all [prepared statements],
   288 ** [sqlite3_blob_close | close] all [BLOB handles], and 
   289 ** [sqlite3_backup_finish | finish] all [sqlite3_backup] objects associated
   290 ** with the [sqlite3] object prior to attempting to close the object.  ^If
   291 ** sqlite3_close_v2() is called on a [database connection] that still has
   292 ** outstanding [prepared statements], [BLOB handles], and/or
   293 ** [sqlite3_backup] objects then it returns [SQLITE_OK] and the deallocation
   294 ** of resources is deferred until all [prepared statements], [BLOB handles],
   295 ** and [sqlite3_backup] objects are also destroyed.
   296 **
   297 ** ^If an [sqlite3] object is destroyed while a transaction is open,
   298 ** the transaction is automatically rolled back.
   299 **
   300 ** The C parameter to [sqlite3_close(C)] and [sqlite3_close_v2(C)]
   301 ** must be either a NULL
   302 ** pointer or an [sqlite3] object pointer obtained
   303 ** from [sqlite3_open()], [sqlite3_open16()], or
   304 ** [sqlite3_open_v2()], and not previously closed.
   305 ** ^Calling sqlite3_close() or sqlite3_close_v2() with a NULL pointer
   306 ** argument is a harmless no-op.
   307 */
   308 SQLITE_API int sqlite3_close(sqlite3*);
   309 SQLITE_API int sqlite3_close_v2(sqlite3*);
   310 
   311 /*
   312 ** The type for a callback function.
   313 ** This is legacy and deprecated.  It is included for historical
   314 ** compatibility and is not documented.
   315 */
   316 typedef int (*sqlite3_callback)(void*,int,char**, char**);
   317 
   318 /*
   319 ** CAPI3REF: One-Step Query Execution Interface
   320 **
   321 ** The sqlite3_exec() interface is a convenience wrapper around
   322 ** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],
   323 ** that allows an application to run multiple statements of SQL
   324 ** without having to use a lot of C code. 
   325 **
   326 ** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
   327 ** semicolon-separate SQL statements passed into its 2nd argument,
   328 ** in the context of the [database connection] passed in as its 1st
   329 ** argument.  ^If the callback function of the 3rd argument to
   330 ** sqlite3_exec() is not NULL, then it is invoked for each result row
   331 ** coming out of the evaluated SQL statements.  ^The 4th argument to
   332 ** sqlite3_exec() is relayed through to the 1st argument of each
   333 ** callback invocation.  ^If the callback pointer to sqlite3_exec()
   334 ** is NULL, then no callback is ever invoked and result rows are
   335 ** ignored.
   336 **
   337 ** ^If an error occurs while evaluating the SQL statements passed into
   338 ** sqlite3_exec(), then execution of the current statement stops and
   339 ** subsequent statements are skipped.  ^If the 5th parameter to sqlite3_exec()
   340 ** is not NULL then any error message is written into memory obtained
   341 ** from [sqlite3_malloc()] and passed back through the 5th parameter.
   342 ** To avoid memory leaks, the application should invoke [sqlite3_free()]
   343 ** on error message strings returned through the 5th parameter of
   344 ** of sqlite3_exec() after the error message string is no longer needed.
   345 ** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
   346 ** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
   347 ** NULL before returning.
   348 **
   349 ** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()
   350 ** routine returns SQLITE_ABORT without invoking the callback again and
   351 ** without running any subsequent SQL statements.
   352 **
   353 ** ^The 2nd argument to the sqlite3_exec() callback function is the
   354 ** number of columns in the result.  ^The 3rd argument to the sqlite3_exec()
   355 ** callback is an array of pointers to strings obtained as if from
   356 ** [sqlite3_column_text()], one for each column.  ^If an element of a
   357 ** result row is NULL then the corresponding string pointer for the
   358 ** sqlite3_exec() callback is a NULL pointer.  ^The 4th argument to the
   359 ** sqlite3_exec() callback is an array of pointers to strings where each
   360 ** entry represents the name of corresponding result column as obtained
   361 ** from [sqlite3_column_name()].
   362 **
   363 ** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer
   364 ** to an empty string, or a pointer that contains only whitespace and/or 
   365 ** SQL comments, then no SQL statements are evaluated and the database
   366 ** is not changed.
   367 **
   368 ** Restrictions:
   369 **
   370 ** <ul>
   371 ** <li> The application must insure that the 1st parameter to sqlite3_exec()
   372 **      is a valid and open [database connection].
   373 ** <li> The application must not close the [database connection] specified by
   374 **      the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
   375 ** <li> The application must not modify the SQL statement text passed into
   376 **      the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.
   377 ** </ul>
   378 */
   379 SQLITE_API int sqlite3_exec(
   380   sqlite3*,                                  /* An open database */
   381   const char *sql,                           /* SQL to be evaluated */
   382   int (*callback)(void*,int,char**,char**),  /* Callback function */
   383   void *,                                    /* 1st argument to callback */
   384   char **errmsg                              /* Error msg written here */
   385 );
   386 
   387 /*
   388 ** CAPI3REF: Result Codes
   389 ** KEYWORDS: {result code definitions}
   390 **
   391 ** Many SQLite functions return an integer result code from the set shown
   392 ** here in order to indicate success or failure.
   393 **
   394 ** New error codes may be added in future versions of SQLite.
   395 **
   396 ** See also: [extended result code definitions]
   397 */
   398 #define SQLITE_OK           0   /* Successful result */
   399 /* beginning-of-error-codes */
   400 #define SQLITE_ERROR        1   /* SQL error or missing database */
   401 #define SQLITE_INTERNAL     2   /* Internal logic error in SQLite */
   402 #define SQLITE_PERM         3   /* Access permission denied */
   403 #define SQLITE_ABORT        4   /* Callback routine requested an abort */
   404 #define SQLITE_BUSY         5   /* The database file is locked */
   405 #define SQLITE_LOCKED       6   /* A table in the database is locked */
   406 #define SQLITE_NOMEM        7   /* A malloc() failed */
   407 #define SQLITE_READONLY     8   /* Attempt to write a readonly database */
   408 #define SQLITE_INTERRUPT    9   /* Operation terminated by sqlite3_interrupt()*/
   409 #define SQLITE_IOERR       10   /* Some kind of disk I/O error occurred */
   410 #define SQLITE_CORRUPT     11   /* The database disk image is malformed */
   411 #define SQLITE_NOTFOUND    12   /* Unknown opcode in sqlite3_file_control() */
   412 #define SQLITE_FULL        13   /* Insertion failed because database is full */
   413 #define SQLITE_CANTOPEN    14   /* Unable to open the database file */
   414 #define SQLITE_PROTOCOL    15   /* Database lock protocol error */
   415 #define SQLITE_EMPTY       16   /* Database is empty */
   416 #define SQLITE_SCHEMA      17   /* The database schema changed */
   417 #define SQLITE_TOOBIG      18   /* String or BLOB exceeds size limit */
   418 #define SQLITE_CONSTRAINT  19   /* Abort due to constraint violation */
   419 #define SQLITE_MISMATCH    20   /* Data type mismatch */
   420 #define SQLITE_MISUSE      21   /* Library used incorrectly */
   421 #define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
   422 #define SQLITE_AUTH        23   /* Authorization denied */
   423 #define SQLITE_FORMAT      24   /* Auxiliary database format error */
   424 #define SQLITE_RANGE       25   /* 2nd parameter to sqlite3_bind out of range */
   425 #define SQLITE_NOTADB      26   /* File opened that is not a database file */
   426 #define SQLITE_NOTICE      27   /* Notifications from sqlite3_log() */
   427 #define SQLITE_WARNING     28   /* Warnings from sqlite3_log() */
   428 #define SQLITE_ROW         100  /* sqlite3_step() has another row ready */
   429 #define SQLITE_DONE        101  /* sqlite3_step() has finished executing */
   430 /* end-of-error-codes */
   431 
   432 /*
   433 ** CAPI3REF: Extended Result Codes
   434 ** KEYWORDS: {extended result code definitions}
   435 **
   436 ** In its default configuration, SQLite API routines return one of 30 integer
   437 ** [result codes].  However, experience has shown that many of
   438 ** these result codes are too coarse-grained.  They do not provide as
   439 ** much information about problems as programmers might like.  In an effort to
   440 ** address this, newer versions of SQLite (version 3.3.8 and later) include
   441 ** support for additional result codes that provide more detailed information
   442 ** about errors. These [extended result codes] are enabled or disabled
   443 ** on a per database connection basis using the
   444 ** [sqlite3_extended_result_codes()] API.  Or, the extended code for
   445 ** the most recent error can be obtained using
   446 ** [sqlite3_extended_errcode()].
   447 */
   448 #define SQLITE_IOERR_READ              (SQLITE_IOERR | (1<<8))
   449 #define SQLITE_IOERR_SHORT_READ        (SQLITE_IOERR | (2<<8))
   450 #define SQLITE_IOERR_WRITE             (SQLITE_IOERR | (3<<8))
   451 #define SQLITE_IOERR_FSYNC             (SQLITE_IOERR | (4<<8))
   452 #define SQLITE_IOERR_DIR_FSYNC         (SQLITE_IOERR | (5<<8))
   453 #define SQLITE_IOERR_TRUNCATE          (SQLITE_IOERR | (6<<8))
   454 #define SQLITE_IOERR_FSTAT             (SQLITE_IOERR | (7<<8))
   455 #define SQLITE_IOERR_UNLOCK            (SQLITE_IOERR | (8<<8))
   456 #define SQLITE_IOERR_RDLOCK            (SQLITE_IOERR | (9<<8))
   457 #define SQLITE_IOERR_DELETE            (SQLITE_IOERR | (10<<8))
   458 #define SQLITE_IOERR_BLOCKED           (SQLITE_IOERR | (11<<8))
   459 #define SQLITE_IOERR_NOMEM             (SQLITE_IOERR | (12<<8))
   460 #define SQLITE_IOERR_ACCESS            (SQLITE_IOERR | (13<<8))
   461 #define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
   462 #define SQLITE_IOERR_LOCK              (SQLITE_IOERR | (15<<8))
   463 #define SQLITE_IOERR_CLOSE             (SQLITE_IOERR | (16<<8))
   464 #define SQLITE_IOERR_DIR_CLOSE         (SQLITE_IOERR | (17<<8))
   465 #define SQLITE_IOERR_SHMOPEN           (SQLITE_IOERR | (18<<8))
   466 #define SQLITE_IOERR_SHMSIZE           (SQLITE_IOERR | (19<<8))
   467 #define SQLITE_IOERR_SHMLOCK           (SQLITE_IOERR | (20<<8))
   468 #define SQLITE_IOERR_SHMMAP            (SQLITE_IOERR | (21<<8))
   469 #define SQLITE_IOERR_SEEK              (SQLITE_IOERR | (22<<8))
   470 #define SQLITE_IOERR_DELETE_NOENT      (SQLITE_IOERR | (23<<8))
   471 #define SQLITE_IOERR_MMAP              (SQLITE_IOERR | (24<<8))
   472 #define SQLITE_IOERR_GETTEMPPATH       (SQLITE_IOERR | (25<<8))
   473 #define SQLITE_IOERR_CONVPATH          (SQLITE_IOERR | (26<<8))
   474 #define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
   475 #define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
   476 #define SQLITE_BUSY_SNAPSHOT           (SQLITE_BUSY   |  (2<<8))
   477 #define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
   478 #define SQLITE_CANTOPEN_ISDIR          (SQLITE_CANTOPEN | (2<<8))
   479 #define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
   480 #define SQLITE_CANTOPEN_CONVPATH       (SQLITE_CANTOPEN | (4<<8))
   481 #define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
   482 #define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
   483 #define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))
   484 #define SQLITE_READONLY_ROLLBACK       (SQLITE_READONLY | (3<<8))
   485 #define SQLITE_READONLY_DBMOVED        (SQLITE_READONLY | (4<<8))
   486 #define SQLITE_ABORT_ROLLBACK          (SQLITE_ABORT | (2<<8))
   487 #define SQLITE_CONSTRAINT_CHECK        (SQLITE_CONSTRAINT | (1<<8))
   488 #define SQLITE_CONSTRAINT_COMMITHOOK   (SQLITE_CONSTRAINT | (2<<8))
   489 #define SQLITE_CONSTRAINT_FOREIGNKEY   (SQLITE_CONSTRAINT | (3<<8))
   490 #define SQLITE_CONSTRAINT_FUNCTION     (SQLITE_CONSTRAINT | (4<<8))
   491 #define SQLITE_CONSTRAINT_NOTNULL      (SQLITE_CONSTRAINT | (5<<8))
   492 #define SQLITE_CONSTRAINT_PRIMARYKEY   (SQLITE_CONSTRAINT | (6<<8))
   493 #define SQLITE_CONSTRAINT_TRIGGER      (SQLITE_CONSTRAINT | (7<<8))
   494 #define SQLITE_CONSTRAINT_UNIQUE       (SQLITE_CONSTRAINT | (8<<8))
   495 #define SQLITE_CONSTRAINT_VTAB         (SQLITE_CONSTRAINT | (9<<8))
   496 #define SQLITE_CONSTRAINT_ROWID        (SQLITE_CONSTRAINT |(10<<8))
   497 #define SQLITE_NOTICE_RECOVER_WAL      (SQLITE_NOTICE | (1<<8))
   498 #define SQLITE_NOTICE_RECOVER_ROLLBACK (SQLITE_NOTICE | (2<<8))
   499 #define SQLITE_WARNING_AUTOINDEX       (SQLITE_WARNING | (1<<8))
   500 
   501 /*
   502 ** CAPI3REF: Flags For File Open Operations
   503 **
   504 ** These bit values are intended for use in the
   505 ** 3rd parameter to the [sqlite3_open_v2()] interface and
   506 ** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
   507 */
   508 #define SQLITE_OPEN_READONLY         0x00000001  /* Ok for sqlite3_open_v2() */
   509 #define SQLITE_OPEN_READWRITE        0x00000002  /* Ok for sqlite3_open_v2() */
   510 #define SQLITE_OPEN_CREATE           0x00000004  /* Ok for sqlite3_open_v2() */
   511 #define SQLITE_OPEN_DELETEONCLOSE    0x00000008  /* VFS only */
   512 #define SQLITE_OPEN_EXCLUSIVE        0x00000010  /* VFS only */
   513 #define SQLITE_OPEN_AUTOPROXY        0x00000020  /* VFS only */
   514 #define SQLITE_OPEN_URI              0x00000040  /* Ok for sqlite3_open_v2() */
   515 #define SQLITE_OPEN_MEMORY           0x00000080  /* Ok for sqlite3_open_v2() */
   516 #define SQLITE_OPEN_MAIN_DB          0x00000100  /* VFS only */
   517 #define SQLITE_OPEN_TEMP_DB          0x00000200  /* VFS only */
   518 #define SQLITE_OPEN_TRANSIENT_DB     0x00000400  /* VFS only */
   519 #define SQLITE_OPEN_MAIN_JOURNAL     0x00000800  /* VFS only */
   520 #define SQLITE_OPEN_TEMP_JOURNAL     0x00001000  /* VFS only */
   521 #define SQLITE_OPEN_SUBJOURNAL       0x00002000  /* VFS only */
   522 #define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */
   523 #define SQLITE_OPEN_NOMUTEX          0x00008000  /* Ok for sqlite3_open_v2() */
   524 #define SQLITE_OPEN_FULLMUTEX        0x00010000  /* Ok for sqlite3_open_v2() */
   525 #define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
   526 #define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */
   527 #define SQLITE_OPEN_WAL              0x00080000  /* VFS only */
   528 
   529 /* Reserved:                         0x00F00000 */
   530 
   531 /*
   532 ** CAPI3REF: Device Characteristics
   533 **
   534 ** The xDeviceCharacteristics method of the [sqlite3_io_methods]
   535 ** object returns an integer which is a vector of these
   536 ** bit values expressing I/O characteristics of the mass storage
   537 ** device that holds the file that the [sqlite3_io_methods]
   538 ** refers to.
   539 **
   540 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
   541 ** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
   542 ** mean that writes of blocks that are nnn bytes in size and
   543 ** are aligned to an address which is an integer multiple of
   544 ** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
   545 ** that when data is appended to a file, the data is appended
   546 ** first then the size of the file is extended, never the other
   547 ** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
   548 ** information is written to disk in the same order as calls
   549 ** to xWrite().  The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that
   550 ** after reboot following a crash or power loss, the only bytes in a
   551 ** file that were written at the application level might have changed
   552 ** and that adjacent bytes, even bytes within the same sector are
   553 ** guaranteed to be unchanged.  The SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
   554 ** flag indicate that a file cannot be deleted when open.  The
   555 ** SQLITE_IOCAP_IMMUTABLE flag indicates that the file is on
   556 ** read-only media and cannot be changed even by processes with
   557 ** elevated privileges.
   558 */
   559 #define SQLITE_IOCAP_ATOMIC                 0x00000001
   560 #define SQLITE_IOCAP_ATOMIC512              0x00000002
   561 #define SQLITE_IOCAP_ATOMIC1K               0x00000004
   562 #define SQLITE_IOCAP_ATOMIC2K               0x00000008
   563 #define SQLITE_IOCAP_ATOMIC4K               0x00000010
   564 #define SQLITE_IOCAP_ATOMIC8K               0x00000020
   565 #define SQLITE_IOCAP_ATOMIC16K              0x00000040
   566 #define SQLITE_IOCAP_ATOMIC32K              0x00000080
   567 #define SQLITE_IOCAP_ATOMIC64K              0x00000100
   568 #define SQLITE_IOCAP_SAFE_APPEND            0x00000200
   569 #define SQLITE_IOCAP_SEQUENTIAL             0x00000400
   570 #define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN  0x00000800
   571 #define SQLITE_IOCAP_POWERSAFE_OVERWRITE    0x00001000
   572 #define SQLITE_IOCAP_IMMUTABLE              0x00002000
   573 
   574 /*
   575 ** CAPI3REF: File Locking Levels
   576 **
   577 ** SQLite uses one of these integer values as the second
   578 ** argument to calls it makes to the xLock() and xUnlock() methods
   579 ** of an [sqlite3_io_methods] object.
   580 */
   581 #define SQLITE_LOCK_NONE          0
   582 #define SQLITE_LOCK_SHARED        1
   583 #define SQLITE_LOCK_RESERVED      2
   584 #define SQLITE_LOCK_PENDING       3
   585 #define SQLITE_LOCK_EXCLUSIVE     4
   586 
   587 /*
   588 ** CAPI3REF: Synchronization Type Flags
   589 **
   590 ** When SQLite invokes the xSync() method of an
   591 ** [sqlite3_io_methods] object it uses a combination of
   592 ** these integer values as the second argument.
   593 **
   594 ** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
   595 ** sync operation only needs to flush data to mass storage.  Inode
   596 ** information need not be flushed. If the lower four bits of the flag
   597 ** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.
   598 ** If the lower four bits equal SQLITE_SYNC_FULL, that means
   599 ** to use Mac OS X style fullsync instead of fsync().
   600 **
   601 ** Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags
   602 ** with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL
   603 ** settings.  The [synchronous pragma] determines when calls to the
   604 ** xSync VFS method occur and applies uniformly across all platforms.
   605 ** The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how
   606 ** energetic or rigorous or forceful the sync operations are and
   607 ** only make a difference on Mac OSX for the default SQLite code.
   608 ** (Third-party VFS implementations might also make the distinction
   609 ** between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the
   610 ** operating systems natively supported by SQLite, only Mac OSX
   611 ** cares about the difference.)
   612 */
   613 #define SQLITE_SYNC_NORMAL        0x00002
   614 #define SQLITE_SYNC_FULL          0x00003
   615 #define SQLITE_SYNC_DATAONLY      0x00010
   616 
   617 /*
   618 ** CAPI3REF: OS Interface Open File Handle
   619 **
   620 ** An [sqlite3_file] object represents an open file in the 
   621 ** [sqlite3_vfs | OS interface layer].  Individual OS interface
   622 ** implementations will
   623 ** want to subclass this object by appending additional fields
   624 ** for their own use.  The pMethods entry is a pointer to an
   625 ** [sqlite3_io_methods] object that defines methods for performing
   626 ** I/O operations on the open file.
   627 */
   628 typedef struct sqlite3_file sqlite3_file;
   629 struct sqlite3_file {
   630   const struct sqlite3_io_methods *pMethods;  /* Methods for an open file */
   631 };
   632 
   633 /*
   634 ** CAPI3REF: OS Interface File Virtual Methods Object
   635 **
   636 ** Every file opened by the [sqlite3_vfs.xOpen] method populates an
   637 ** [sqlite3_file] object (or, more commonly, a subclass of the
   638 ** [sqlite3_file] object) with a pointer to an instance of this object.
   639 ** This object defines the methods used to perform various operations
   640 ** against the open file represented by the [sqlite3_file] object.
   641 **
   642 ** If the [sqlite3_vfs.xOpen] method sets the sqlite3_file.pMethods element 
   643 ** to a non-NULL pointer, then the sqlite3_io_methods.xClose method
   644 ** may be invoked even if the [sqlite3_vfs.xOpen] reported that it failed.  The
   645 ** only way to prevent a call to xClose following a failed [sqlite3_vfs.xOpen]
   646 ** is for the [sqlite3_vfs.xOpen] to set the sqlite3_file.pMethods element
   647 ** to NULL.
   648 **
   649 ** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
   650 ** [SQLITE_SYNC_FULL].  The first choice is the normal fsync().
   651 ** The second choice is a Mac OS X style fullsync.  The [SQLITE_SYNC_DATAONLY]
   652 ** flag may be ORed in to indicate that only the data of the file
   653 ** and not its inode needs to be synced.
   654 **
   655 ** The integer values to xLock() and xUnlock() are one of
   656 ** <ul>
   657 ** <li> [SQLITE_LOCK_NONE],
   658 ** <li> [SQLITE_LOCK_SHARED],
   659 ** <li> [SQLITE_LOCK_RESERVED],
   660 ** <li> [SQLITE_LOCK_PENDING], or
   661 ** <li> [SQLITE_LOCK_EXCLUSIVE].
   662 ** </ul>
   663 ** xLock() increases the lock. xUnlock() decreases the lock.
   664 ** The xCheckReservedLock() method checks whether any database connection,
   665 ** either in this process or in some other process, is holding a RESERVED,
   666 ** PENDING, or EXCLUSIVE lock on the file.  It returns true
   667 ** if such a lock exists and false otherwise.
   668 **
   669 ** The xFileControl() method is a generic interface that allows custom
   670 ** VFS implementations to directly control an open file using the
   671 ** [sqlite3_file_control()] interface.  The second "op" argument is an
   672 ** integer opcode.  The third argument is a generic pointer intended to
   673 ** point to a structure that may contain arguments or space in which to
   674 ** write return values.  Potential uses for xFileControl() might be
   675 ** functions to enable blocking locks with timeouts, to change the
   676 ** locking strategy (for example to use dot-file locks), to inquire
   677 ** about the status of a lock, or to break stale locks.  The SQLite
   678 ** core reserves all opcodes less than 100 for its own use.
   679 ** A [file control opcodes | list of opcodes] less than 100 is available.
   680 ** Applications that define a custom xFileControl method should use opcodes
   681 ** greater than 100 to avoid conflicts.  VFS implementations should
   682 ** return [SQLITE_NOTFOUND] for file control opcodes that they do not
   683 ** recognize.
   684 **
   685 ** The xSectorSize() method returns the sector size of the
   686 ** device that underlies the file.  The sector size is the
   687 ** minimum write that can be performed without disturbing
   688 ** other bytes in the file.  The xDeviceCharacteristics()
   689 ** method returns a bit vector describing behaviors of the
   690 ** underlying device:
   691 **
   692 ** <ul>
   693 ** <li> [SQLITE_IOCAP_ATOMIC]
   694 ** <li> [SQLITE_IOCAP_ATOMIC512]
   695 ** <li> [SQLITE_IOCAP_ATOMIC1K]
   696 ** <li> [SQLITE_IOCAP_ATOMIC2K]
   697 ** <li> [SQLITE_IOCAP_ATOMIC4K]
   698 ** <li> [SQLITE_IOCAP_ATOMIC8K]
   699 ** <li> [SQLITE_IOCAP_ATOMIC16K]
   700 ** <li> [SQLITE_IOCAP_ATOMIC32K]
   701 ** <li> [SQLITE_IOCAP_ATOMIC64K]
   702 ** <li> [SQLITE_IOCAP_SAFE_APPEND]
   703 ** <li> [SQLITE_IOCAP_SEQUENTIAL]
   704 ** </ul>
   705 **
   706 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
   707 ** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
   708 ** mean that writes of blocks that are nnn bytes in size and
   709 ** are aligned to an address which is an integer multiple of
   710 ** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
   711 ** that when data is appended to a file, the data is appended
   712 ** first then the size of the file is extended, never the other
   713 ** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
   714 ** information is written to disk in the same order as calls
   715 ** to xWrite().
   716 **
   717 ** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
   718 ** in the unread portions of the buffer with zeros.  A VFS that
   719 ** fails to zero-fill short reads might seem to work.  However,
   720 ** failure to zero-fill short reads will eventually lead to
   721 ** database corruption.
   722 */
   723 typedef struct sqlite3_io_methods sqlite3_io_methods;
   724 struct sqlite3_io_methods {
   725   int iVersion;
   726   int (*xClose)(sqlite3_file*);
   727   int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
   728   int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
   729   int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
   730   int (*xSync)(sqlite3_file*, int flags);
   731   int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
   732   int (*xLock)(sqlite3_file*, int);
   733   int (*xUnlock)(sqlite3_file*, int);
   734   int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
   735   int (*xFileControl)(sqlite3_file*, int op, void *pArg);
   736   int (*xSectorSize)(sqlite3_file*);
   737   int (*xDeviceCharacteristics)(sqlite3_file*);
   738   /* Methods above are valid for version 1 */
   739   int (*xShmMap)(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
   740   int (*xShmLock)(sqlite3_file*, int offset, int n, int flags);
   741   void (*xShmBarrier)(sqlite3_file*);
   742   int (*xShmUnmap)(sqlite3_file*, int deleteFlag);
   743   /* Methods above are valid for version 2 */
   744   int (*xFetch)(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
   745   int (*xUnfetch)(sqlite3_file*, sqlite3_int64 iOfst, void *p);
   746   /* Methods above are valid for version 3 */
   747   /* Additional methods may be added in future releases */
   748 };
   749 
   750 /*
   751 ** CAPI3REF: Standard File Control Opcodes
   752 ** KEYWORDS: {file control opcodes} {file control opcode}
   753 **
   754 ** These integer constants are opcodes for the xFileControl method
   755 ** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
   756 ** interface.
   757 **
   758 ** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging.  This
   759 ** opcode causes the xFileControl method to write the current state of
   760 ** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
   761 ** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
   762 ** into an integer that the pArg argument points to. This capability
   763 ** is used during testing and only needs to be supported when SQLITE_TEST
   764 ** is defined.
   765 ** <ul>
   766 ** <li>[[SQLITE_FCNTL_SIZE_HINT]]
   767 ** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
   768 ** layer a hint of how large the database file will grow to be during the
   769 ** current transaction.  This hint is not guaranteed to be accurate but it
   770 ** is often close.  The underlying VFS might choose to preallocate database
   771 ** file space based on this hint in order to help writes to the database
   772 ** file run faster.
   773 **
   774 ** <li>[[SQLITE_FCNTL_CHUNK_SIZE]]
   775 ** The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS
   776 ** extends and truncates the database file in chunks of a size specified
   777 ** by the user. The fourth argument to [sqlite3_file_control()] should 
   778 ** point to an integer (type int) containing the new chunk-size to use
   779 ** for the nominated database. Allocating database file space in large
   780 ** chunks (say 1MB at a time), may reduce file-system fragmentation and
   781 ** improve performance on some systems.
   782 **
   783 ** <li>[[SQLITE_FCNTL_FILE_POINTER]]
   784 ** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
   785 ** to the [sqlite3_file] object associated with a particular database
   786 ** connection.  See the [sqlite3_file_control()] documentation for
   787 ** additional information.
   788 **
   789 ** <li>[[SQLITE_FCNTL_SYNC_OMITTED]]
   790 ** No longer in use.
   791 **
   792 ** <li>[[SQLITE_FCNTL_SYNC]]
   793 ** The [SQLITE_FCNTL_SYNC] opcode is generated internally by SQLite and
   794 ** sent to the VFS immediately before the xSync method is invoked on a
   795 ** database file descriptor. Or, if the xSync method is not invoked 
   796 ** because the user has configured SQLite with 
   797 ** [PRAGMA synchronous | PRAGMA synchronous=OFF] it is invoked in place 
   798 ** of the xSync method. In most cases, the pointer argument passed with
   799 ** this file-control is NULL. However, if the database file is being synced
   800 ** as part of a multi-database commit, the argument points to a nul-terminated
   801 ** string containing the transactions master-journal file name. VFSes that 
   802 ** do not need this signal should silently ignore this opcode. Applications 
   803 ** should not call [sqlite3_file_control()] with this opcode as doing so may 
   804 ** disrupt the operation of the specialized VFSes that do require it.  
   805 **
   806 ** <li>[[SQLITE_FCNTL_COMMIT_PHASETWO]]
   807 ** The [SQLITE_FCNTL_COMMIT_PHASETWO] opcode is generated internally by SQLite
   808 ** and sent to the VFS after a transaction has been committed immediately
   809 ** but before the database is unlocked. VFSes that do not need this signal
   810 ** should silently ignore this opcode. Applications should not call
   811 ** [sqlite3_file_control()] with this opcode as doing so may disrupt the 
   812 ** operation of the specialized VFSes that do require it.  
   813 **
   814 ** <li>[[SQLITE_FCNTL_WIN32_AV_RETRY]]
   815 ** ^The [SQLITE_FCNTL_WIN32_AV_RETRY] opcode is used to configure automatic
   816 ** retry counts and intervals for certain disk I/O operations for the
   817 ** windows [VFS] in order to provide robustness in the presence of
   818 ** anti-virus programs.  By default, the windows VFS will retry file read,
   819 ** file write, and file delete operations up to 10 times, with a delay
   820 ** of 25 milliseconds before the first retry and with the delay increasing
   821 ** by an additional 25 milliseconds with each subsequent retry.  This
   822 ** opcode allows these two values (10 retries and 25 milliseconds of delay)
   823 ** to be adjusted.  The values are changed for all database connections
   824 ** within the same process.  The argument is a pointer to an array of two
   825 ** integers where the first integer i the new retry count and the second
   826 ** integer is the delay.  If either integer is negative, then the setting
   827 ** is not changed but instead the prior value of that setting is written
   828 ** into the array entry, allowing the current retry settings to be
   829 ** interrogated.  The zDbName parameter is ignored.
   830 **
   831 ** <li>[[SQLITE_FCNTL_PERSIST_WAL]]
   832 ** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the
   833 ** persistent [WAL | Write Ahead Log] setting.  By default, the auxiliary
   834 ** write ahead log and shared memory files used for transaction control
   835 ** are automatically deleted when the latest connection to the database
   836 ** closes.  Setting persistent WAL mode causes those files to persist after
   837 ** close.  Persisting the files is useful when other processes that do not
   838 ** have write permission on the directory containing the database file want
   839 ** to read the database file, as the WAL and shared memory files must exist
   840 ** in order for the database to be readable.  The fourth parameter to
   841 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
   842 ** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
   843 ** WAL mode.  If the integer is -1, then it is overwritten with the current
   844 ** WAL persistence setting.
   845 **
   846 ** <li>[[SQLITE_FCNTL_POWERSAFE_OVERWRITE]]
   847 ** ^The [SQLITE_FCNTL_POWERSAFE_OVERWRITE] opcode is used to set or query the
   848 ** persistent "powersafe-overwrite" or "PSOW" setting.  The PSOW setting
   849 ** determines the [SQLITE_IOCAP_POWERSAFE_OVERWRITE] bit of the
   850 ** xDeviceCharacteristics methods. The fourth parameter to
   851 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
   852 ** That integer is 0 to disable zero-damage mode or 1 to enable zero-damage
   853 ** mode.  If the integer is -1, then it is overwritten with the current
   854 ** zero-damage mode setting.
   855 **
   856 ** <li>[[SQLITE_FCNTL_OVERWRITE]]
   857 ** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
   858 ** a write transaction to indicate that, unless it is rolled back for some
   859 ** reason, the entire database file will be overwritten by the current 
   860 ** transaction. This is used by VACUUM operations.
   861 **
   862 ** <li>[[SQLITE_FCNTL_VFSNAME]]
   863 ** ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of
   864 ** all [VFSes] in the VFS stack.  The names are of all VFS shims and the
   865 ** final bottom-level VFS are written into memory obtained from 
   866 ** [sqlite3_malloc()] and the result is stored in the char* variable
   867 ** that the fourth parameter of [sqlite3_file_control()] points to.
   868 ** The caller is responsible for freeing the memory when done.  As with
   869 ** all file-control actions, there is no guarantee that this will actually
   870 ** do anything.  Callers should initialize the char* variable to a NULL
   871 ** pointer in case this file-control is not implemented.  This file-control
   872 ** is intended for diagnostic use only.
   873 **
   874 ** <li>[[SQLITE_FCNTL_PRAGMA]]
   875 ** ^Whenever a [PRAGMA] statement is parsed, an [SQLITE_FCNTL_PRAGMA] 
   876 ** file control is sent to the open [sqlite3_file] object corresponding
   877 ** to the database file to which the pragma statement refers. ^The argument
   878 ** to the [SQLITE_FCNTL_PRAGMA] file control is an array of
   879 ** pointers to strings (char**) in which the second element of the array
   880 ** is the name of the pragma and the third element is the argument to the
   881 ** pragma or NULL if the pragma has no argument.  ^The handler for an
   882 ** [SQLITE_FCNTL_PRAGMA] file control can optionally make the first element
   883 ** of the char** argument point to a string obtained from [sqlite3_mprintf()]
   884 ** or the equivalent and that string will become the result of the pragma or
   885 ** the error message if the pragma fails. ^If the
   886 ** [SQLITE_FCNTL_PRAGMA] file control returns [SQLITE_NOTFOUND], then normal 
   887 ** [PRAGMA] processing continues.  ^If the [SQLITE_FCNTL_PRAGMA]
   888 ** file control returns [SQLITE_OK], then the parser assumes that the
   889 ** VFS has handled the PRAGMA itself and the parser generates a no-op
   890 ** prepared statement.  ^If the [SQLITE_FCNTL_PRAGMA] file control returns
   891 ** any result code other than [SQLITE_OK] or [SQLITE_NOTFOUND], that means
   892 ** that the VFS encountered an error while handling the [PRAGMA] and the
   893 ** compilation of the PRAGMA fails with an error.  ^The [SQLITE_FCNTL_PRAGMA]
   894 ** file control occurs at the beginning of pragma statement analysis and so
   895 ** it is able to override built-in [PRAGMA] statements.
   896 **
   897 ** <li>[[SQLITE_FCNTL_BUSYHANDLER]]
   898 ** ^The [SQLITE_FCNTL_BUSYHANDLER]
   899 ** file-control may be invoked by SQLite on the database file handle
   900 ** shortly after it is opened in order to provide a custom VFS with access
   901 ** to the connections busy-handler callback. The argument is of type (void **)
   902 ** - an array of two (void *) values. The first (void *) actually points
   903 ** to a function of type (int (*)(void *)). In order to invoke the connections
   904 ** busy-handler, this function should be invoked with the second (void *) in
   905 ** the array as the only argument. If it returns non-zero, then the operation
   906 ** should be retried. If it returns zero, the custom VFS should abandon the
   907 ** current operation.
   908 **
   909 ** <li>[[SQLITE_FCNTL_TEMPFILENAME]]
   910 ** ^Application can invoke the [SQLITE_FCNTL_TEMPFILENAME] file-control
   911 ** to have SQLite generate a
   912 ** temporary filename using the same algorithm that is followed to generate
   913 ** temporary filenames for TEMP tables and other internal uses.  The
   914 ** argument should be a char** which will be filled with the filename
   915 ** written into memory obtained from [sqlite3_malloc()].  The caller should
   916 ** invoke [sqlite3_free()] on the result to avoid a memory leak.
   917 **
   918 ** <li>[[SQLITE_FCNTL_MMAP_SIZE]]
   919 ** The [SQLITE_FCNTL_MMAP_SIZE] file control is used to query or set the
   920 ** maximum number of bytes that will be used for memory-mapped I/O.
   921 ** The argument is a pointer to a value of type sqlite3_int64 that
   922 ** is an advisory maximum number of bytes in the file to memory map.  The
   923 ** pointer is overwritten with the old value.  The limit is not changed if
   924 ** the value originally pointed to is negative, and so the current limit 
   925 ** can be queried by passing in a pointer to a negative number.  This
   926 ** file-control is used internally to implement [PRAGMA mmap_size].
   927 **
   928 ** <li>[[SQLITE_FCNTL_TRACE]]
   929 ** The [SQLITE_FCNTL_TRACE] file control provides advisory information
   930 ** to the VFS about what the higher layers of the SQLite stack are doing.
   931 ** This file control is used by some VFS activity tracing [shims].
   932 ** The argument is a zero-terminated string.  Higher layers in the
   933 ** SQLite stack may generate instances of this file control if
   934 ** the [SQLITE_USE_FCNTL_TRACE] compile-time option is enabled.
   935 **
   936 ** <li>[[SQLITE_FCNTL_HAS_MOVED]]
   937 ** The [SQLITE_FCNTL_HAS_MOVED] file control interprets its argument as a
   938 ** pointer to an integer and it writes a boolean into that integer depending
   939 ** on whether or not the file has been renamed, moved, or deleted since it
   940 ** was first opened.
   941 **
   942 ** <li>[[SQLITE_FCNTL_WIN32_SET_HANDLE]]
   943 ** The [SQLITE_FCNTL_WIN32_SET_HANDLE] opcode is used for debugging.  This
   944 ** opcode causes the xFileControl method to swap the file handle with the one
   945 ** pointed to by the pArg argument.  This capability is used during testing
   946 ** and only needs to be supported when SQLITE_TEST is defined.
   947 **
   948 ** </ul>
   949 */
   950 #define SQLITE_FCNTL_LOCKSTATE               1
   951 #define SQLITE_GET_LOCKPROXYFILE             2
   952 #define SQLITE_SET_LOCKPROXYFILE             3
   953 #define SQLITE_LAST_ERRNO                    4
   954 #define SQLITE_FCNTL_SIZE_HINT               5
   955 #define SQLITE_FCNTL_CHUNK_SIZE              6
   956 #define SQLITE_FCNTL_FILE_POINTER            7
   957 #define SQLITE_FCNTL_SYNC_OMITTED            8
   958 #define SQLITE_FCNTL_WIN32_AV_RETRY          9
   959 #define SQLITE_FCNTL_PERSIST_WAL            10
   960 #define SQLITE_FCNTL_OVERWRITE              11
   961 #define SQLITE_FCNTL_VFSNAME                12
   962 #define SQLITE_FCNTL_POWERSAFE_OVERWRITE    13
   963 #define SQLITE_FCNTL_PRAGMA                 14
   964 #define SQLITE_FCNTL_BUSYHANDLER            15
   965 #define SQLITE_FCNTL_TEMPFILENAME           16
   966 #define SQLITE_FCNTL_MMAP_SIZE              18
   967 #define SQLITE_FCNTL_TRACE                  19
   968 #define SQLITE_FCNTL_HAS_MOVED              20
   969 #define SQLITE_FCNTL_SYNC                   21
   970 #define SQLITE_FCNTL_COMMIT_PHASETWO        22
   971 #define SQLITE_FCNTL_WIN32_SET_HANDLE       23
   972 
   973 /*
   974 ** CAPI3REF: Mutex Handle
   975 **
   976 ** The mutex module within SQLite defines [sqlite3_mutex] to be an
   977 ** abstract type for a mutex object.  The SQLite core never looks
   978 ** at the internal representation of an [sqlite3_mutex].  It only
   979 ** deals with pointers to the [sqlite3_mutex] object.
   980 **
   981 ** Mutexes are created using [sqlite3_mutex_alloc()].
   982 */
   983 typedef struct sqlite3_mutex sqlite3_mutex;
   984 
   985 /*
   986 ** CAPI3REF: OS Interface Object
   987 **
   988 ** An instance of the sqlite3_vfs object defines the interface between
   989 ** the SQLite core and the underlying operating system.  The "vfs"
   990 ** in the name of the object stands for "virtual file system".  See
   991 ** the [VFS | VFS documentation] for further information.
   992 **
   993 ** The value of the iVersion field is initially 1 but may be larger in
   994 ** future versions of SQLite.  Additional fields may be appended to this
   995 ** object when the iVersion value is increased.  Note that the structure
   996 ** of the sqlite3_vfs object changes in the transaction between
   997 ** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not
   998 ** modified.
   999 **
  1000 ** The szOsFile field is the size of the subclassed [sqlite3_file]
  1001 ** structure used by this VFS.  mxPathname is the maximum length of
  1002 ** a pathname in this VFS.
  1003 **
  1004 ** Registered sqlite3_vfs objects are kept on a linked list formed by
  1005 ** the pNext pointer.  The [sqlite3_vfs_register()]
  1006 ** and [sqlite3_vfs_unregister()] interfaces manage this list
  1007 ** in a thread-safe way.  The [sqlite3_vfs_find()] interface
  1008 ** searches the list.  Neither the application code nor the VFS
  1009 ** implementation should use the pNext pointer.
  1010 **
  1011 ** The pNext field is the only field in the sqlite3_vfs
  1012 ** structure that SQLite will ever modify.  SQLite will only access
  1013 ** or modify this field while holding a particular static mutex.
  1014 ** The application should never modify anything within the sqlite3_vfs
  1015 ** object once the object has been registered.
  1016 **
  1017 ** The zName field holds the name of the VFS module.  The name must
  1018 ** be unique across all VFS modules.
  1019 **
  1020 ** [[sqlite3_vfs.xOpen]]
  1021 ** ^SQLite guarantees that the zFilename parameter to xOpen
  1022 ** is either a NULL pointer or string obtained
  1023 ** from xFullPathname() with an optional suffix added.
  1024 ** ^If a suffix is added to the zFilename parameter, it will
  1025 ** consist of a single "-" character followed by no more than
  1026 ** 11 alphanumeric and/or "-" characters.
  1027 ** ^SQLite further guarantees that
  1028 ** the string will be valid and unchanged until xClose() is
  1029 ** called. Because of the previous sentence,
  1030 ** the [sqlite3_file] can safely store a pointer to the
  1031 ** filename if it needs to remember the filename for some reason.
  1032 ** If the zFilename parameter to xOpen is a NULL pointer then xOpen
  1033 ** must invent its own temporary name for the file.  ^Whenever the 
  1034 ** xFilename parameter is NULL it will also be the case that the
  1035 ** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
  1036 **
  1037 ** The flags argument to xOpen() includes all bits set in
  1038 ** the flags argument to [sqlite3_open_v2()].  Or if [sqlite3_open()]
  1039 ** or [sqlite3_open16()] is used, then flags includes at least
  1040 ** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]. 
  1041 ** If xOpen() opens a file read-only then it sets *pOutFlags to
  1042 ** include [SQLITE_OPEN_READONLY].  Other bits in *pOutFlags may be set.
  1043 **
  1044 ** ^(SQLite will also add one of the following flags to the xOpen()
  1045 ** call, depending on the object being opened:
  1046 **
  1047 ** <ul>
  1048 ** <li>  [SQLITE_OPEN_MAIN_DB]
  1049 ** <li>  [SQLITE_OPEN_MAIN_JOURNAL]
  1050 ** <li>  [SQLITE_OPEN_TEMP_DB]
  1051 ** <li>  [SQLITE_OPEN_TEMP_JOURNAL]
  1052 ** <li>  [SQLITE_OPEN_TRANSIENT_DB]
  1053 ** <li>  [SQLITE_OPEN_SUBJOURNAL]
  1054 ** <li>  [SQLITE_OPEN_MASTER_JOURNAL]
  1055 ** <li>  [SQLITE_OPEN_WAL]
  1056 ** </ul>)^
  1057 **
  1058 ** The file I/O implementation can use the object type flags to
  1059 ** change the way it deals with files.  For example, an application
  1060 ** that does not care about crash recovery or rollback might make
  1061 ** the open of a journal file a no-op.  Writes to this journal would
  1062 ** also be no-ops, and any attempt to read the journal would return
  1063 ** SQLITE_IOERR.  Or the implementation might recognize that a database
  1064 ** file will be doing page-aligned sector reads and writes in a random
  1065 ** order and set up its I/O subsystem accordingly.
  1066 **
  1067 ** SQLite might also add one of the following flags to the xOpen method:
  1068 **
  1069 ** <ul>
  1070 ** <li> [SQLITE_OPEN_DELETEONCLOSE]
  1071 ** <li> [SQLITE_OPEN_EXCLUSIVE]
  1072 ** </ul>
  1073 **
  1074 ** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
  1075 ** deleted when it is closed.  ^The [SQLITE_OPEN_DELETEONCLOSE]
  1076 ** will be set for TEMP databases and their journals, transient
  1077 ** databases, and subjournals.
  1078 **
  1079 ** ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction
  1080 ** with the [SQLITE_OPEN_CREATE] flag, which are both directly
  1081 ** analogous to the O_EXCL and O_CREAT flags of the POSIX open()
  1082 ** API.  The SQLITE_OPEN_EXCLUSIVE flag, when paired with the 
  1083 ** SQLITE_OPEN_CREATE, is used to indicate that file should always
  1084 ** be created, and that it is an error if it already exists.
  1085 ** It is <i>not</i> used to indicate the file should be opened 
  1086 ** for exclusive access.
  1087 **
  1088 ** ^At least szOsFile bytes of memory are allocated by SQLite
  1089 ** to hold the  [sqlite3_file] structure passed as the third
  1090 ** argument to xOpen.  The xOpen method does not have to
  1091 ** allocate the structure; it should just fill it in.  Note that
  1092 ** the xOpen method must set the sqlite3_file.pMethods to either
  1093 ** a valid [sqlite3_io_methods] object or to NULL.  xOpen must do
  1094 ** this even if the open fails.  SQLite expects that the sqlite3_file.pMethods
  1095 ** element will be valid after xOpen returns regardless of the success
  1096 ** or failure of the xOpen call.
  1097 **
  1098 ** [[sqlite3_vfs.xAccess]]
  1099 ** ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
  1100 ** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
  1101 ** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
  1102 ** to test whether a file is at least readable.   The file can be a
  1103 ** directory.
  1104 **
  1105 ** ^SQLite will always allocate at least mxPathname+1 bytes for the
  1106 ** output buffer xFullPathname.  The exact size of the output buffer
  1107 ** is also passed as a parameter to both  methods. If the output buffer
  1108 ** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
  1109 ** handled as a fatal error by SQLite, vfs implementations should endeavor
  1110 ** to prevent this by setting mxPathname to a sufficiently large value.
  1111 **
  1112 ** The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64()
  1113 ** interfaces are not strictly a part of the filesystem, but they are
  1114 ** included in the VFS structure for completeness.
  1115 ** The xRandomness() function attempts to return nBytes bytes
  1116 ** of good-quality randomness into zOut.  The return value is
  1117 ** the actual number of bytes of randomness obtained.
  1118 ** The xSleep() method causes the calling thread to sleep for at
  1119 ** least the number of microseconds given.  ^The xCurrentTime()
  1120 ** method returns a Julian Day Number for the current date and time as
  1121 ** a floating point value.
  1122 ** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
  1123 ** Day Number multiplied by 86400000 (the number of milliseconds in 
  1124 ** a 24-hour day).  
  1125 ** ^SQLite will use the xCurrentTimeInt64() method to get the current
  1126 ** date and time if that method is available (if iVersion is 2 or 
  1127 ** greater and the function pointer is not NULL) and will fall back
  1128 ** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
  1129 **
  1130 ** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
  1131 ** are not used by the SQLite core.  These optional interfaces are provided
  1132 ** by some VFSes to facilitate testing of the VFS code. By overriding 
  1133 ** system calls with functions under its control, a test program can
  1134 ** simulate faults and error conditions that would otherwise be difficult
  1135 ** or impossible to induce.  The set of system calls that can be overridden
  1136 ** varies from one VFS to another, and from one version of the same VFS to the
  1137 ** next.  Applications that use these interfaces must be prepared for any
  1138 ** or all of these interfaces to be NULL or for their behavior to change
  1139 ** from one release to the next.  Applications must not attempt to access
  1140 ** any of these methods if the iVersion of the VFS is less than 3.
  1141 */
  1142 typedef struct sqlite3_vfs sqlite3_vfs;
  1143 typedef void (*sqlite3_syscall_ptr)(void);
  1144 struct sqlite3_vfs {
  1145   int iVersion;            /* Structure version number (currently 3) */
  1146   int szOsFile;            /* Size of subclassed sqlite3_file */
  1147   int mxPathname;          /* Maximum file pathname length */
  1148   sqlite3_vfs *pNext;      /* Next registered VFS */
  1149   const char *zName;       /* Name of this virtual file system */
  1150   void *pAppData;          /* Pointer to application-specific data */
  1151   int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
  1152                int flags, int *pOutFlags);
  1153   int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
  1154   int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
  1155   int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
  1156   void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
  1157   void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
  1158   void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
  1159   void (*xDlClose)(sqlite3_vfs*, void*);
  1160   int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
  1161   int (*xSleep)(sqlite3_vfs*, int microseconds);
  1162   int (*xCurrentTime)(sqlite3_vfs*, double*);
  1163   int (*xGetLastError)(sqlite3_vfs*, int, char *);
  1164   /*
  1165   ** The methods above are in version 1 of the sqlite_vfs object
  1166   ** definition.  Those that follow are added in version 2 or later
  1167   */
  1168   int (*xCurrentTimeInt64)(sqlite3_vfs*, sqlite3_int64*);
  1169   /*
  1170   ** The methods above are in versions 1 and 2 of the sqlite_vfs object.
  1171   ** Those below are for version 3 and greater.
  1172   */
  1173   int (*xSetSystemCall)(sqlite3_vfs*, const char *zName, sqlite3_syscall_ptr);
  1174   sqlite3_syscall_ptr (*xGetSystemCall)(sqlite3_vfs*, const char *zName);
  1175   const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
  1176   /*
  1177   ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
  1178   ** New fields may be appended in figure versions.  The iVersion
  1179   ** value will increment whenever this happens. 
  1180   */
  1181 };
  1182 
  1183 /*
  1184 ** CAPI3REF: Flags for the xAccess VFS method
  1185 **
  1186 ** These integer constants can be used as the third parameter to
  1187 ** the xAccess method of an [sqlite3_vfs] object.  They determine
  1188 ** what kind of permissions the xAccess method is looking for.
  1189 ** With SQLITE_ACCESS_EXISTS, the xAccess method
  1190 ** simply checks whether the file exists.
  1191 ** With SQLITE_ACCESS_READWRITE, the xAccess method
  1192 ** checks whether the named directory is both readable and writable
  1193 ** (in other words, if files can be added, removed, and renamed within
  1194 ** the directory).
  1195 ** The SQLITE_ACCESS_READWRITE constant is currently used only by the
  1196 ** [temp_store_directory pragma], though this could change in a future
  1197 ** release of SQLite.
  1198 ** With SQLITE_ACCESS_READ, the xAccess method
  1199 ** checks whether the file is readable.  The SQLITE_ACCESS_READ constant is
  1200 ** currently unused, though it might be used in a future release of
  1201 ** SQLite.
  1202 */
  1203 #define SQLITE_ACCESS_EXISTS    0
  1204 #define SQLITE_ACCESS_READWRITE 1   /* Used by PRAGMA temp_store_directory */
  1205 #define SQLITE_ACCESS_READ      2   /* Unused */
  1206 
  1207 /*
  1208 ** CAPI3REF: Flags for the xShmLock VFS method
  1209 **
  1210 ** These integer constants define the various locking operations
  1211 ** allowed by the xShmLock method of [sqlite3_io_methods].  The
  1212 ** following are the only legal combinations of flags to the
  1213 ** xShmLock method:
  1214 **
  1215 ** <ul>
  1216 ** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_SHARED
  1217 ** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE
  1218 ** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED
  1219 ** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE
  1220 ** </ul>
  1221 **
  1222 ** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
  1223 ** was given no the corresponding lock.  
  1224 **
  1225 ** The xShmLock method can transition between unlocked and SHARED or
  1226 ** between unlocked and EXCLUSIVE.  It cannot transition between SHARED
  1227 ** and EXCLUSIVE.
  1228 */
  1229 #define SQLITE_SHM_UNLOCK       1
  1230 #define SQLITE_SHM_LOCK         2
  1231 #define SQLITE_SHM_SHARED       4
  1232 #define SQLITE_SHM_EXCLUSIVE    8
  1233 
  1234 /*
  1235 ** CAPI3REF: Maximum xShmLock index
  1236 **
  1237 ** The xShmLock method on [sqlite3_io_methods] may use values
  1238 ** between 0 and this upper bound as its "offset" argument.
  1239 ** The SQLite core will never attempt to acquire or release a
  1240 ** lock outside of this range
  1241 */
  1242 #define SQLITE_SHM_NLOCK        8
  1243 
  1244 
  1245 /*
  1246 ** CAPI3REF: Initialize The SQLite Library
  1247 **
  1248 ** ^The sqlite3_initialize() routine initializes the
  1249 ** SQLite library.  ^The sqlite3_shutdown() routine
  1250 ** deallocates any resources that were allocated by sqlite3_initialize().
  1251 ** These routines are designed to aid in process initialization and
  1252 ** shutdown on embedded systems.  Workstation applications using
  1253 ** SQLite normally do not need to invoke either of these routines.
  1254 **
  1255 ** A call to sqlite3_initialize() is an "effective" call if it is
  1256 ** the first time sqlite3_initialize() is invoked during the lifetime of
  1257 ** the process, or if it is the first time sqlite3_initialize() is invoked
  1258 ** following a call to sqlite3_shutdown().  ^(Only an effective call
  1259 ** of sqlite3_initialize() does any initialization.  All other calls
  1260 ** are harmless no-ops.)^
  1261 **
  1262 ** A call to sqlite3_shutdown() is an "effective" call if it is the first
  1263 ** call to sqlite3_shutdown() since the last sqlite3_initialize().  ^(Only
  1264 ** an effective call to sqlite3_shutdown() does any deinitialization.
  1265 ** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^
  1266 **
  1267 ** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()
  1268 ** is not.  The sqlite3_shutdown() interface must only be called from a
  1269 ** single thread.  All open [database connections] must be closed and all
  1270 ** other SQLite resources must be deallocated prior to invoking
  1271 ** sqlite3_shutdown().
  1272 **
  1273 ** Among other things, ^sqlite3_initialize() will invoke
  1274 ** sqlite3_os_init().  Similarly, ^sqlite3_shutdown()
  1275 ** will invoke sqlite3_os_end().
  1276 **
  1277 ** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.
  1278 ** ^If for some reason, sqlite3_initialize() is unable to initialize
  1279 ** the library (perhaps it is unable to allocate a needed resource such
  1280 ** as a mutex) it returns an [error code] other than [SQLITE_OK].
  1281 **
  1282 ** ^The sqlite3_initialize() routine is called internally by many other
  1283 ** SQLite interfaces so that an application usually does not need to
  1284 ** invoke sqlite3_initialize() directly.  For example, [sqlite3_open()]
  1285 ** calls sqlite3_initialize() so the SQLite library will be automatically
  1286 ** initialized when [sqlite3_open()] is called if it has not be initialized
  1287 ** already.  ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
  1288 ** compile-time option, then the automatic calls to sqlite3_initialize()
  1289 ** are omitted and the application must call sqlite3_initialize() directly
  1290 ** prior to using any other SQLite interface.  For maximum portability,
  1291 ** it is recommended that applications always invoke sqlite3_initialize()
  1292 ** directly prior to using any other SQLite interface.  Future releases
  1293 ** of SQLite may require this.  In other words, the behavior exhibited
  1294 ** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
  1295 ** default behavior in some future release of SQLite.
  1296 **
  1297 ** The sqlite3_os_init() routine does operating-system specific
  1298 ** initialization of the SQLite library.  The sqlite3_os_end()
  1299 ** routine undoes the effect of sqlite3_os_init().  Typical tasks
  1300 ** performed by these routines include allocation or deallocation
  1301 ** of static resources, initialization of global variables,
  1302 ** setting up a default [sqlite3_vfs] module, or setting up
  1303 ** a default configuration using [sqlite3_config()].
  1304 **
  1305 ** The application should never invoke either sqlite3_os_init()
  1306 ** or sqlite3_os_end() directly.  The application should only invoke
  1307 ** sqlite3_initialize() and sqlite3_shutdown().  The sqlite3_os_init()
  1308 ** interface is called automatically by sqlite3_initialize() and
  1309 ** sqlite3_os_end() is called by sqlite3_shutdown().  Appropriate
  1310 ** implementations for sqlite3_os_init() and sqlite3_os_end()
  1311 ** are built into SQLite when it is compiled for Unix, Windows, or OS/2.
  1312 ** When [custom builds | built for other platforms]
  1313 ** (using the [SQLITE_OS_OTHER=1] compile-time
  1314 ** option) the application must supply a suitable implementation for
  1315 ** sqlite3_os_init() and sqlite3_os_end().  An application-supplied
  1316 ** implementation of sqlite3_os_init() or sqlite3_os_end()
  1317 ** must return [SQLITE_OK] on success and some other [error code] upon
  1318 ** failure.
  1319 */
  1320 SQLITE_API int sqlite3_initialize(void);
  1321 SQLITE_API int sqlite3_shutdown(void);
  1322 SQLITE_API int sqlite3_os_init(void);
  1323 SQLITE_API int sqlite3_os_end(void);
  1324 
  1325 /*
  1326 ** CAPI3REF: Configuring The SQLite Library
  1327 **
  1328 ** The sqlite3_config() interface is used to make global configuration
  1329 ** changes to SQLite in order to tune SQLite to the specific needs of
  1330 ** the application.  The default configuration is recommended for most
  1331 ** applications and so this routine is usually not necessary.  It is
  1332 ** provided to support rare applications with unusual needs.
  1333 **
  1334 ** The sqlite3_config() interface is not threadsafe.  The application
  1335 ** must insure that no other SQLite interfaces are invoked by other
  1336 ** threads while sqlite3_config() is running.  Furthermore, sqlite3_config()
  1337 ** may only be invoked prior to library initialization using
  1338 ** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
  1339 ** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
  1340 ** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.
  1341 ** Note, however, that ^sqlite3_config() can be called as part of the
  1342 ** implementation of an application-defined [sqlite3_os_init()].
  1343 **
  1344 ** The first argument to sqlite3_config() is an integer
  1345 ** [configuration option] that determines
  1346 ** what property of SQLite is to be configured.  Subsequent arguments
  1347 ** vary depending on the [configuration option]
  1348 ** in the first argument.
  1349 **
  1350 ** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
  1351 ** ^If the option is unknown or SQLite is unable to set the option
  1352 ** then this routine returns a non-zero [error code].
  1353 */
  1354 SQLITE_API int sqlite3_config(int, ...);
  1355 
  1356 /*
  1357 ** CAPI3REF: Configure database connections
  1358 **
  1359 ** The sqlite3_db_config() interface is used to make configuration
  1360 ** changes to a [database connection].  The interface is similar to
  1361 ** [sqlite3_config()] except that the changes apply to a single
  1362 ** [database connection] (specified in the first argument).
  1363 **
  1364 ** The second argument to sqlite3_db_config(D,V,...)  is the
  1365 ** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code 
  1366 ** that indicates what aspect of the [database connection] is being configured.
  1367 ** Subsequent arguments vary depending on the configuration verb.
  1368 **
  1369 ** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
  1370 ** the call is considered successful.
  1371 */
  1372 SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);
  1373 
  1374 /*
  1375 ** CAPI3REF: Memory Allocation Routines
  1376 **
  1377 ** An instance of this object defines the interface between SQLite
  1378 ** and low-level memory allocation routines.
  1379 **
  1380 ** This object is used in only one place in the SQLite interface.
  1381 ** A pointer to an instance of this object is the argument to
  1382 ** [sqlite3_config()] when the configuration option is
  1383 ** [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC].  
  1384 ** By creating an instance of this object
  1385 ** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])
  1386 ** during configuration, an application can specify an alternative
  1387 ** memory allocation subsystem for SQLite to use for all of its
  1388 ** dynamic memory needs.
  1389 **
  1390 ** Note that SQLite comes with several [built-in memory allocators]
  1391 ** that are perfectly adequate for the overwhelming majority of applications
  1392 ** and that this object is only useful to a tiny minority of applications
  1393 ** with specialized memory allocation requirements.  This object is
  1394 ** also used during testing of SQLite in order to specify an alternative
  1395 ** memory allocator that simulates memory out-of-memory conditions in
  1396 ** order to verify that SQLite recovers gracefully from such
  1397 ** conditions.
  1398 **
  1399 ** The xMalloc, xRealloc, and xFree methods must work like the
  1400 ** malloc(), realloc() and free() functions from the standard C library.
  1401 ** ^SQLite guarantees that the second argument to
  1402 ** xRealloc is always a value returned by a prior call to xRoundup.
  1403 **
  1404 ** xSize should return the allocated size of a memory allocation
  1405 ** previously obtained from xMalloc or xRealloc.  The allocated size
  1406 ** is always at least as big as the requested size but may be larger.
  1407 **
  1408 ** The xRoundup method returns what would be the allocated size of
  1409 ** a memory allocation given a particular requested size.  Most memory
  1410 ** allocators round up memory allocations at least to the next multiple
  1411 ** of 8.  Some allocators round up to a larger multiple or to a power of 2.
  1412 ** Every memory allocation request coming in through [sqlite3_malloc()]
  1413 ** or [sqlite3_realloc()] first calls xRoundup.  If xRoundup returns 0, 
  1414 ** that causes the corresponding memory allocation to fail.
  1415 **
  1416 ** The xInit method initializes the memory allocator.  For example,
  1417 ** it might allocate any require mutexes or initialize internal data
  1418 ** structures.  The xShutdown method is invoked (indirectly) by
  1419 ** [sqlite3_shutdown()] and should deallocate any resources acquired
  1420 ** by xInit.  The pAppData pointer is used as the only parameter to
  1421 ** xInit and xShutdown.
  1422 **
  1423 ** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes
  1424 ** the xInit method, so the xInit method need not be threadsafe.  The
  1425 ** xShutdown method is only called from [sqlite3_shutdown()] so it does
  1426 ** not need to be threadsafe either.  For all other methods, SQLite
  1427 ** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the
  1428 ** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which
  1429 ** it is by default) and so the methods are automatically serialized.
  1430 ** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other
  1431 ** methods must be threadsafe or else make their own arrangements for
  1432 ** serialization.
  1433 **
  1434 ** SQLite will never invoke xInit() more than once without an intervening
  1435 ** call to xShutdown().
  1436 */
  1437 typedef struct sqlite3_mem_methods sqlite3_mem_methods;
  1438 struct sqlite3_mem_methods {
  1439   void *(*xMalloc)(int);         /* Memory allocation function */
  1440   void (*xFree)(void*);          /* Free a prior allocation */
  1441   void *(*xRealloc)(void*,int);  /* Resize an allocation */
  1442   int (*xSize)(void*);           /* Return the size of an allocation */
  1443   int (*xRoundup)(int);          /* Round up request size to allocation size */
  1444   int (*xInit)(void*);           /* Initialize the memory allocator */
  1445   void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
  1446   void *pAppData;                /* Argument to xInit() and xShutdown() */
  1447 };
  1448 
  1449 /*
  1450 ** CAPI3REF: Configuration Options
  1451 ** KEYWORDS: {configuration option}
  1452 **
  1453 ** These constants are the available integer configuration options that
  1454 ** can be passed as the first argument to the [sqlite3_config()] interface.
  1455 **
  1456 ** New configuration options may be added in future releases of SQLite.
  1457 ** Existing configuration options might be discontinued.  Applications
  1458 ** should check the return code from [sqlite3_config()] to make sure that
  1459 ** the call worked.  The [sqlite3_config()] interface will return a
  1460 ** non-zero [error code] if a discontinued or unsupported configuration option
  1461 ** is invoked.
  1462 **
  1463 ** <dl>
  1464 ** [[SQLITE_CONFIG_SINGLETHREAD]] <dt>SQLITE_CONFIG_SINGLETHREAD</dt>
  1465 ** <dd>There are no arguments to this option.  ^This option sets the
  1466 ** [threading mode] to Single-thread.  In other words, it disables
  1467 ** all mutexing and puts SQLite into a mode where it can only be used
  1468 ** by a single thread.   ^If SQLite is compiled with
  1469 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1470 ** it is not possible to change the [threading mode] from its default
  1471 ** value of Single-thread and so [sqlite3_config()] will return 
  1472 ** [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD
  1473 ** configuration option.</dd>
  1474 **
  1475 ** [[SQLITE_CONFIG_MULTITHREAD]] <dt>SQLITE_CONFIG_MULTITHREAD</dt>
  1476 ** <dd>There are no arguments to this option.  ^This option sets the
  1477 ** [threading mode] to Multi-thread.  In other words, it disables
  1478 ** mutexing on [database connection] and [prepared statement] objects.
  1479 ** The application is responsible for serializing access to
  1480 ** [database connections] and [prepared statements].  But other mutexes
  1481 ** are enabled so that SQLite will be safe to use in a multi-threaded
  1482 ** environment as long as no two threads attempt to use the same
  1483 ** [database connection] at the same time.  ^If SQLite is compiled with
  1484 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1485 ** it is not possible to set the Multi-thread [threading mode] and
  1486 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
  1487 ** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>
  1488 **
  1489 ** [[SQLITE_CONFIG_SERIALIZED]] <dt>SQLITE_CONFIG_SERIALIZED</dt>
  1490 ** <dd>There are no arguments to this option.  ^This option sets the
  1491 ** [threading mode] to Serialized. In other words, this option enables
  1492 ** all mutexes including the recursive
  1493 ** mutexes on [database connection] and [prepared statement] objects.
  1494 ** In this mode (which is the default when SQLite is compiled with
  1495 ** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
  1496 ** to [database connections] and [prepared statements] so that the
  1497 ** application is free to use the same [database connection] or the
  1498 ** same [prepared statement] in different threads at the same time.
  1499 ** ^If SQLite is compiled with
  1500 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1501 ** it is not possible to set the Serialized [threading mode] and
  1502 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
  1503 ** SQLITE_CONFIG_SERIALIZED configuration option.</dd>
  1504 **
  1505 ** [[SQLITE_CONFIG_MALLOC]] <dt>SQLITE_CONFIG_MALLOC</dt>
  1506 ** <dd> ^(This option takes a single argument which is a pointer to an
  1507 ** instance of the [sqlite3_mem_methods] structure.  The argument specifies
  1508 ** alternative low-level memory allocation routines to be used in place of
  1509 ** the memory allocation routines built into SQLite.)^ ^SQLite makes
  1510 ** its own private copy of the content of the [sqlite3_mem_methods] structure
  1511 ** before the [sqlite3_config()] call returns.</dd>
  1512 **
  1513 ** [[SQLITE_CONFIG_GETMALLOC]] <dt>SQLITE_CONFIG_GETMALLOC</dt>
  1514 ** <dd> ^(This option takes a single argument which is a pointer to an
  1515 ** instance of the [sqlite3_mem_methods] structure.  The [sqlite3_mem_methods]
  1516 ** structure is filled with the currently defined memory allocation routines.)^
  1517 ** This option can be used to overload the default memory allocation
  1518 ** routines with a wrapper that simulations memory allocation failure or
  1519 ** tracks memory usage, for example. </dd>
  1520 **
  1521 ** [[SQLITE_CONFIG_MEMSTATUS]] <dt>SQLITE_CONFIG_MEMSTATUS</dt>
  1522 ** <dd> ^This option takes single argument of type int, interpreted as a 
  1523 ** boolean, which enables or disables the collection of memory allocation 
  1524 ** statistics. ^(When memory allocation statistics are disabled, the 
  1525 ** following SQLite interfaces become non-operational:
  1526 **   <ul>
  1527 **   <li> [sqlite3_memory_used()]
  1528 **   <li> [sqlite3_memory_highwater()]
  1529 **   <li> [sqlite3_soft_heap_limit64()]
  1530 **   <li> [sqlite3_status()]
  1531 **   </ul>)^
  1532 ** ^Memory allocation statistics are enabled by default unless SQLite is
  1533 ** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
  1534 ** allocation statistics are disabled by default.
  1535 ** </dd>
  1536 **
  1537 ** [[SQLITE_CONFIG_SCRATCH]] <dt>SQLITE_CONFIG_SCRATCH</dt>
  1538 ** <dd> ^This option specifies a static memory buffer that SQLite can use for
  1539 ** scratch memory.  There are three arguments:  A pointer an 8-byte
  1540 ** aligned memory buffer from which the scratch allocations will be
  1541 ** drawn, the size of each scratch allocation (sz),
  1542 ** and the maximum number of scratch allocations (N).  The sz
  1543 ** argument must be a multiple of 16.
  1544 ** The first argument must be a pointer to an 8-byte aligned buffer
  1545 ** of at least sz*N bytes of memory.
  1546 ** ^SQLite will use no more than two scratch buffers per thread.  So
  1547 ** N should be set to twice the expected maximum number of threads.
  1548 ** ^SQLite will never require a scratch buffer that is more than 6
  1549 ** times the database page size. ^If SQLite needs needs additional
  1550 ** scratch memory beyond what is provided by this configuration option, then 
  1551 ** [sqlite3_malloc()] will be used to obtain the memory needed.</dd>
  1552 **
  1553 ** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
  1554 ** <dd> ^This option specifies a static memory buffer that SQLite can use for
  1555 ** the database page cache with the default page cache implementation.  
  1556 ** This configuration should not be used if an application-define page
  1557 ** cache implementation is loaded using the SQLITE_CONFIG_PCACHE2 option.
  1558 ** There are three arguments to this option: A pointer to 8-byte aligned
  1559 ** memory, the size of each page buffer (sz), and the number of pages (N).
  1560 ** The sz argument should be the size of the largest database page
  1561 ** (a power of two between 512 and 32768) plus a little extra for each
  1562 ** page header.  ^The page header size is 20 to 40 bytes depending on
  1563 ** the host architecture.  ^It is harmless, apart from the wasted memory,
  1564 ** to make sz a little too large.  The first
  1565 ** argument should point to an allocation of at least sz*N bytes of memory.
  1566 ** ^SQLite will use the memory provided by the first argument to satisfy its
  1567 ** memory needs for the first N pages that it adds to cache.  ^If additional
  1568 ** page cache memory is needed beyond what is provided by this option, then
  1569 ** SQLite goes to [sqlite3_malloc()] for the additional storage space.
  1570 ** The pointer in the first argument must
  1571 ** be aligned to an 8-byte boundary or subsequent behavior of SQLite
  1572 ** will be undefined.</dd>
  1573 **
  1574 ** [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt>
  1575 ** <dd> ^This option specifies a static memory buffer that SQLite will use
  1576 ** for all of its dynamic memory allocation needs beyond those provided
  1577 ** for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE].
  1578 ** There are three arguments: An 8-byte aligned pointer to the memory,
  1579 ** the number of bytes in the memory buffer, and the minimum allocation size.
  1580 ** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
  1581 ** to using its default memory allocator (the system malloc() implementation),
  1582 ** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
  1583 ** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
  1584 ** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
  1585 ** allocator is engaged to handle all of SQLites memory allocation needs.
  1586 ** The first pointer (the memory pointer) must be aligned to an 8-byte
  1587 ** boundary or subsequent behavior of SQLite will be undefined.
  1588 ** The minimum allocation size is capped at 2**12. Reasonable values
  1589 ** for the minimum allocation size are 2**5 through 2**8.</dd>
  1590 **
  1591 ** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
  1592 ** <dd> ^(This option takes a single argument which is a pointer to an
  1593 ** instance of the [sqlite3_mutex_methods] structure.  The argument specifies
  1594 ** alternative low-level mutex routines to be used in place
  1595 ** the mutex routines built into SQLite.)^  ^SQLite makes a copy of the
  1596 ** content of the [sqlite3_mutex_methods] structure before the call to
  1597 ** [sqlite3_config()] returns. ^If SQLite is compiled with
  1598 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1599 ** the entire mutexing subsystem is omitted from the build and hence calls to
  1600 ** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
  1601 ** return [SQLITE_ERROR].</dd>
  1602 **
  1603 ** [[SQLITE_CONFIG_GETMUTEX]] <dt>SQLITE_CONFIG_GETMUTEX</dt>
  1604 ** <dd> ^(This option takes a single argument which is a pointer to an
  1605 ** instance of the [sqlite3_mutex_methods] structure.  The
  1606 ** [sqlite3_mutex_methods]
  1607 ** structure is filled with the currently defined mutex routines.)^
  1608 ** This option can be used to overload the default mutex allocation
  1609 ** routines with a wrapper used to track mutex usage for performance
  1610 ** profiling or testing, for example.   ^If SQLite is compiled with
  1611 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1612 ** the entire mutexing subsystem is omitted from the build and hence calls to
  1613 ** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will
  1614 ** return [SQLITE_ERROR].</dd>
  1615 **
  1616 ** [[SQLITE_CONFIG_LOOKASIDE]] <dt>SQLITE_CONFIG_LOOKASIDE</dt>
  1617 ** <dd> ^(This option takes two arguments that determine the default
  1618 ** memory allocation for the lookaside memory allocator on each
  1619 ** [database connection].  The first argument is the
  1620 ** size of each lookaside buffer slot and the second is the number of
  1621 ** slots allocated to each database connection.)^  ^(This option sets the
  1622 ** <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]
  1623 ** verb to [sqlite3_db_config()] can be used to change the lookaside
  1624 ** configuration on individual connections.)^ </dd>
  1625 **
  1626 ** [[SQLITE_CONFIG_PCACHE2]] <dt>SQLITE_CONFIG_PCACHE2</dt>
  1627 ** <dd> ^(This option takes a single argument which is a pointer to
  1628 ** an [sqlite3_pcache_methods2] object.  This object specifies the interface
  1629 ** to a custom page cache implementation.)^  ^SQLite makes a copy of the
  1630 ** object and uses it for page cache memory allocations.</dd>
  1631 **
  1632 ** [[SQLITE_CONFIG_GETPCACHE2]] <dt>SQLITE_CONFIG_GETPCACHE2</dt>
  1633 ** <dd> ^(This option takes a single argument which is a pointer to an
  1634 ** [sqlite3_pcache_methods2] object.  SQLite copies of the current
  1635 ** page cache implementation into that object.)^ </dd>
  1636 **
  1637 ** [[SQLITE_CONFIG_LOG]] <dt>SQLITE_CONFIG_LOG</dt>
  1638 ** <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite
  1639 ** global [error log].
  1640 ** (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
  1641 ** function with a call signature of void(*)(void*,int,const char*), 
  1642 ** and a pointer to void. ^If the function pointer is not NULL, it is
  1643 ** invoked by [sqlite3_log()] to process each logging event.  ^If the
  1644 ** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
  1645 ** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
  1646 ** passed through as the first parameter to the application-defined logger
  1647 ** function whenever that function is invoked.  ^The second parameter to
  1648 ** the logger function is a copy of the first parameter to the corresponding
  1649 ** [sqlite3_log()] call and is intended to be a [result code] or an
  1650 ** [extended result code].  ^The third parameter passed to the logger is
  1651 ** log message after formatting via [sqlite3_snprintf()].
  1652 ** The SQLite logging interface is not reentrant; the logger function
  1653 ** supplied by the application must not invoke any SQLite interface.
  1654 ** In a multi-threaded application, the application-defined logger
  1655 ** function must be threadsafe. </dd>
  1656 **
  1657 ** [[SQLITE_CONFIG_URI]] <dt>SQLITE_CONFIG_URI
  1658 ** <dd>^(This option takes a single argument of type int. If non-zero, then
  1659 ** URI handling is globally enabled. If the parameter is zero, then URI handling
  1660 ** is globally disabled.)^ ^If URI handling is globally enabled, all filenames
  1661 ** passed to [sqlite3_open()], [sqlite3_open_v2()], [sqlite3_open16()] or
  1662 ** specified as part of [ATTACH] commands are interpreted as URIs, regardless
  1663 ** of whether or not the [SQLITE_OPEN_URI] flag is set when the database
  1664 ** connection is opened. ^If it is globally disabled, filenames are
  1665 ** only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the
  1666 ** database connection is opened. ^(By default, URI handling is globally
  1667 ** disabled. The default value may be changed by compiling with the
  1668 ** [SQLITE_USE_URI] symbol defined.)^
  1669 **
  1670 ** [[SQLITE_CONFIG_COVERING_INDEX_SCAN]] <dt>SQLITE_CONFIG_COVERING_INDEX_SCAN
  1671 ** <dd>^This option takes a single integer argument which is interpreted as
  1672 ** a boolean in order to enable or disable the use of covering indices for
  1673 ** full table scans in the query optimizer.  ^The default setting is determined
  1674 ** by the [SQLITE_ALLOW_COVERING_INDEX_SCAN] compile-time option, or is "on"
  1675 ** if that compile-time option is omitted.
  1676 ** The ability to disable the use of covering indices for full table scans
  1677 ** is because some incorrectly coded legacy applications might malfunction
  1678 ** when the optimization is enabled.  Providing the ability to
  1679 ** disable the optimization allows the older, buggy application code to work
  1680 ** without change even with newer versions of SQLite.
  1681 **
  1682 ** [[SQLITE_CONFIG_PCACHE]] [[SQLITE_CONFIG_GETPCACHE]]
  1683 ** <dt>SQLITE_CONFIG_PCACHE and SQLITE_CONFIG_GETPCACHE
  1684 ** <dd> These options are obsolete and should not be used by new code.
  1685 ** They are retained for backwards compatibility but are now no-ops.
  1686 ** </dd>
  1687 **
  1688 ** [[SQLITE_CONFIG_SQLLOG]]
  1689 ** <dt>SQLITE_CONFIG_SQLLOG
  1690 ** <dd>This option is only available if sqlite is compiled with the
  1691 ** [SQLITE_ENABLE_SQLLOG] pre-processor macro defined. The first argument should
  1692 ** be a pointer to a function of type void(*)(void*,sqlite3*,const char*, int).
  1693 ** The second should be of type (void*). The callback is invoked by the library
  1694 ** in three separate circumstances, identified by the value passed as the
  1695 ** fourth parameter. If the fourth parameter is 0, then the database connection
  1696 ** passed as the second argument has just been opened. The third argument
  1697 ** points to a buffer containing the name of the main database file. If the
  1698 ** fourth parameter is 1, then the SQL statement that the third parameter
  1699 ** points to has just been executed. Or, if the fourth parameter is 2, then
  1700 ** the connection being passed as the second parameter is being closed. The
  1701 ** third parameter is passed NULL In this case.  An example of using this
  1702 ** configuration option can be seen in the "test_sqllog.c" source file in
  1703 ** the canonical SQLite source tree.</dd>
  1704 **
  1705 ** [[SQLITE_CONFIG_MMAP_SIZE]]
  1706 ** <dt>SQLITE_CONFIG_MMAP_SIZE
  1707 ** <dd>^SQLITE_CONFIG_MMAP_SIZE takes two 64-bit integer (sqlite3_int64) values
  1708 ** that are the default mmap size limit (the default setting for
  1709 ** [PRAGMA mmap_size]) and the maximum allowed mmap size limit.
  1710 ** ^The default setting can be overridden by each database connection using
  1711 ** either the [PRAGMA mmap_size] command, or by using the
  1712 ** [SQLITE_FCNTL_MMAP_SIZE] file control.  ^(The maximum allowed mmap size
  1713 ** cannot be changed at run-time.  Nor may the maximum allowed mmap size
  1714 ** exceed the compile-time maximum mmap size set by the
  1715 ** [SQLITE_MAX_MMAP_SIZE] compile-time option.)^
  1716 ** ^If either argument to this option is negative, then that argument is
  1717 ** changed to its compile-time default.
  1718 **
  1719 ** [[SQLITE_CONFIG_WIN32_HEAPSIZE]]
  1720 ** <dt>SQLITE_CONFIG_WIN32_HEAPSIZE
  1721 ** <dd>^This option is only available if SQLite is compiled for Windows
  1722 ** with the [SQLITE_WIN32_MALLOC] pre-processor macro defined.
  1723 ** SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value
  1724 ** that specifies the maximum size of the created heap.
  1725 ** </dl>
  1726 */
  1727 #define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
  1728 #define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
  1729 #define SQLITE_CONFIG_SERIALIZED    3  /* nil */
  1730 #define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
  1731 #define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
  1732 #define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
  1733 #define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
  1734 #define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
  1735 #define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
  1736 #define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
  1737 #define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
  1738 /* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 
  1739 #define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
  1740 #define SQLITE_CONFIG_PCACHE       14  /* no-op */
  1741 #define SQLITE_CONFIG_GETPCACHE    15  /* no-op */
  1742 #define SQLITE_CONFIG_LOG          16  /* xFunc, void* */
  1743 #define SQLITE_CONFIG_URI          17  /* int */
  1744 #define SQLITE_CONFIG_PCACHE2      18  /* sqlite3_pcache_methods2* */
  1745 #define SQLITE_CONFIG_GETPCACHE2   19  /* sqlite3_pcache_methods2* */
  1746 #define SQLITE_CONFIG_COVERING_INDEX_SCAN 20  /* int */
  1747 #define SQLITE_CONFIG_SQLLOG       21  /* xSqllog, void* */
  1748 #define SQLITE_CONFIG_MMAP_SIZE    22  /* sqlite3_int64, sqlite3_int64 */
  1749 #define SQLITE_CONFIG_WIN32_HEAPSIZE      23  /* int nByte */
  1750 
  1751 /*
  1752 ** CAPI3REF: Database Connection Configuration Options
  1753 **
  1754 ** These constants are the available integer configuration options that
  1755 ** can be passed as the second argument to the [sqlite3_db_config()] interface.
  1756 **
  1757 ** New configuration options may be added in future releases of SQLite.
  1758 ** Existing configuration options might be discontinued.  Applications
  1759 ** should check the return code from [sqlite3_db_config()] to make sure that
  1760 ** the call worked.  ^The [sqlite3_db_config()] interface will return a
  1761 ** non-zero [error code] if a discontinued or unsupported configuration option
  1762 ** is invoked.
  1763 **
  1764 ** <dl>
  1765 ** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
  1766 ** <dd> ^This option takes three additional arguments that determine the 
  1767 ** [lookaside memory allocator] configuration for the [database connection].
  1768 ** ^The first argument (the third parameter to [sqlite3_db_config()] is a
  1769 ** pointer to a memory buffer to use for lookaside memory.
  1770 ** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
  1771 ** may be NULL in which case SQLite will allocate the
  1772 ** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
  1773 ** size of each lookaside buffer slot.  ^The third argument is the number of
  1774 ** slots.  The size of the buffer in the first argument must be greater than
  1775 ** or equal to the product of the second and third arguments.  The buffer
  1776 ** must be aligned to an 8-byte boundary.  ^If the second argument to
  1777 ** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally
  1778 ** rounded down to the next smaller multiple of 8.  ^(The lookaside memory
  1779 ** configuration for a database connection can only be changed when that
  1780 ** connection is not currently using lookaside memory, or in other words
  1781 ** when the "current value" returned by
  1782 ** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
  1783 ** Any attempt to change the lookaside memory configuration when lookaside
  1784 ** memory is in use leaves the configuration unchanged and returns 
  1785 ** [SQLITE_BUSY].)^</dd>
  1786 **
  1787 ** <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>
  1788 ** <dd> ^This option is used to enable or disable the enforcement of
  1789 ** [foreign key constraints].  There should be two additional arguments.
  1790 ** The first argument is an integer which is 0 to disable FK enforcement,
  1791 ** positive to enable FK enforcement or negative to leave FK enforcement
  1792 ** unchanged.  The second parameter is a pointer to an integer into which
  1793 ** is written 0 or 1 to indicate whether FK enforcement is off or on
  1794 ** following this call.  The second parameter may be a NULL pointer, in
  1795 ** which case the FK enforcement setting is not reported back. </dd>
  1796 **
  1797 ** <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>
  1798 ** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
  1799 ** There should be two additional arguments.
  1800 ** The first argument is an integer which is 0 to disable triggers,
  1801 ** positive to enable triggers or negative to leave the setting unchanged.
  1802 ** The second parameter is a pointer to an integer into which
  1803 ** is written 0 or 1 to indicate whether triggers are disabled or enabled
  1804 ** following this call.  The second parameter may be a NULL pointer, in
  1805 ** which case the trigger setting is not reported back. </dd>
  1806 **
  1807 ** </dl>
  1808 */
  1809 #define SQLITE_DBCONFIG_LOOKASIDE       1001  /* void* int int */
  1810 #define SQLITE_DBCONFIG_ENABLE_FKEY     1002  /* int int* */
  1811 #define SQLITE_DBCONFIG_ENABLE_TRIGGER  1003  /* int int* */
  1812 
  1813 
  1814 /*
  1815 ** CAPI3REF: Enable Or Disable Extended Result Codes
  1816 **
  1817 ** ^The sqlite3_extended_result_codes() routine enables or disables the
  1818 ** [extended result codes] feature of SQLite. ^The extended result
  1819 ** codes are disabled by default for historical compatibility.
  1820 */
  1821 SQLITE_API int sqlite3_extended_result_codes(sqlite3*, int onoff);
  1822 
  1823 /*
  1824 ** CAPI3REF: Last Insert Rowid
  1825 **
  1826 ** ^Each entry in most SQLite tables (except for [WITHOUT ROWID] tables)
  1827 ** has a unique 64-bit signed
  1828 ** integer key called the [ROWID | "rowid"]. ^The rowid is always available
  1829 ** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
  1830 ** names are not also used by explicitly declared columns. ^If
  1831 ** the table has a column of type [INTEGER PRIMARY KEY] then that column
  1832 ** is another alias for the rowid.
  1833 **
  1834 ** ^The sqlite3_last_insert_rowid(D) interface returns the [rowid] of the 
  1835 ** most recent successful [INSERT] into a rowid table or [virtual table]
  1836 ** on database connection D.
  1837 ** ^Inserts into [WITHOUT ROWID] tables are not recorded.
  1838 ** ^If no successful [INSERT]s into rowid tables
  1839 ** have ever occurred on the database connection D, 
  1840 ** then sqlite3_last_insert_rowid(D) returns zero.
  1841 **
  1842 ** ^(If an [INSERT] occurs within a trigger or within a [virtual table]
  1843 ** method, then this routine will return the [rowid] of the inserted
  1844 ** row as long as the trigger or virtual table method is running.
  1845 ** But once the trigger or virtual table method ends, the value returned 
  1846 ** by this routine reverts to what it was before the trigger or virtual
  1847 ** table method began.)^
  1848 **
  1849 ** ^An [INSERT] that fails due to a constraint violation is not a
  1850 ** successful [INSERT] and does not change the value returned by this
  1851 ** routine.  ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
  1852 ** and INSERT OR ABORT make no changes to the return value of this
  1853 ** routine when their insertion fails.  ^(When INSERT OR REPLACE
  1854 ** encounters a constraint violation, it does not fail.  The
  1855 ** INSERT continues to completion after deleting rows that caused
  1856 ** the constraint problem so INSERT OR REPLACE will always change
  1857 ** the return value of this interface.)^
  1858 **
  1859 ** ^For the purposes of this routine, an [INSERT] is considered to
  1860 ** be successful even if it is subsequently rolled back.
  1861 **
  1862 ** This function is accessible to SQL statements via the
  1863 ** [last_insert_rowid() SQL function].
  1864 **
  1865 ** If a separate thread performs a new [INSERT] on the same
  1866 ** database connection while the [sqlite3_last_insert_rowid()]
  1867 ** function is running and thus changes the last insert [rowid],
  1868 ** then the value returned by [sqlite3_last_insert_rowid()] is
  1869 ** unpredictable and might not equal either the old or the new
  1870 ** last insert [rowid].
  1871 */
  1872 SQLITE_API sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);
  1873 
  1874 /*
  1875 ** CAPI3REF: Count The Number Of Rows Modified
  1876 **
  1877 ** ^This function returns the number of database rows that were changed
  1878 ** or inserted or deleted by the most recently completed SQL statement
  1879 ** on the [database connection] specified by the first parameter.
  1880 ** ^(Only changes that are directly specified by the [INSERT], [UPDATE],
  1881 ** or [DELETE] statement are counted.  Auxiliary changes caused by
  1882 ** triggers or [foreign key actions] are not counted.)^ Use the
  1883 ** [sqlite3_total_changes()] function to find the total number of changes
  1884 ** including changes caused by triggers and foreign key actions.
  1885 **
  1886 ** ^Changes to a view that are simulated by an [INSTEAD OF trigger]
  1887 ** are not counted.  Only real table changes are counted.
  1888 **
  1889 ** ^(A "row change" is a change to a single row of a single table
  1890 ** caused by an INSERT, DELETE, or UPDATE statement.  Rows that
  1891 ** are changed as side effects of [REPLACE] constraint resolution,
  1892 ** rollback, ABORT processing, [DROP TABLE], or by any other
  1893 ** mechanisms do not count as direct row changes.)^
  1894 **
  1895 ** A "trigger context" is a scope of execution that begins and
  1896 ** ends with the script of a [CREATE TRIGGER | trigger]. 
  1897 ** Most SQL statements are
  1898 ** evaluated outside of any trigger.  This is the "top level"
  1899 ** trigger context.  If a trigger fires from the top level, a
  1900 ** new trigger context is entered for the duration of that one
  1901 ** trigger.  Subtriggers create subcontexts for their duration.
  1902 **
  1903 ** ^Calling [sqlite3_exec()] or [sqlite3_step()] recursively does
  1904 ** not create a new trigger context.
  1905 **
  1906 ** ^This function returns the number of direct row changes in the
  1907 ** most recent INSERT, UPDATE, or DELETE statement within the same
  1908 ** trigger context.
  1909 **
  1910 ** ^Thus, when called from the top level, this function returns the
  1911 ** number of changes in the most recent INSERT, UPDATE, or DELETE
  1912 ** that also occurred at the top level.  ^(Within the body of a trigger,
  1913 ** the sqlite3_changes() interface can be called to find the number of
  1914 ** changes in the most recently completed INSERT, UPDATE, or DELETE
  1915 ** statement within the body of the same trigger.
  1916 ** However, the number returned does not include changes
  1917 ** caused by subtriggers since those have their own context.)^
  1918 **
  1919 ** See also the [sqlite3_total_changes()] interface, the
  1920 ** [count_changes pragma], and the [changes() SQL function].
  1921 **
  1922 ** If a separate thread makes changes on the same database connection
  1923 ** while [sqlite3_changes()] is running then the value returned
  1924 ** is unpredictable and not meaningful.
  1925 */
  1926 SQLITE_API int sqlite3_changes(sqlite3*);
  1927 
  1928 /*
  1929 ** CAPI3REF: Total Number Of Rows Modified
  1930 **
  1931 ** ^This function returns the number of row changes caused by [INSERT],
  1932 ** [UPDATE] or [DELETE] statements since the [database connection] was opened.
  1933 ** ^(The count returned by sqlite3_total_changes() includes all changes
  1934 ** from all [CREATE TRIGGER | trigger] contexts and changes made by
  1935 ** [foreign key actions]. However,
  1936 ** the count does not include changes used to implement [REPLACE] constraints,
  1937 ** do rollbacks or ABORT processing, or [DROP TABLE] processing.  The
  1938 ** count does not include rows of views that fire an [INSTEAD OF trigger],
  1939 ** though if the INSTEAD OF trigger makes changes of its own, those changes 
  1940 ** are counted.)^
  1941 ** ^The sqlite3_total_changes() function counts the changes as soon as
  1942 ** the statement that makes them is completed (when the statement handle
  1943 ** is passed to [sqlite3_reset()] or [sqlite3_finalize()]).
  1944 **
  1945 ** See also the [sqlite3_changes()] interface, the
  1946 ** [count_changes pragma], and the [total_changes() SQL function].
  1947 **
  1948 ** If a separate thread makes changes on the same database connection
  1949 ** while [sqlite3_total_changes()] is running then the value
  1950 ** returned is unpredictable and not meaningful.
  1951 */
  1952 SQLITE_API int sqlite3_total_changes(sqlite3*);
  1953 
  1954 /*
  1955 ** CAPI3REF: Interrupt A Long-Running Query
  1956 **
  1957 ** ^This function causes any pending database operation to abort and
  1958 ** return at its earliest opportunity. This routine is typically
  1959 ** called in response to a user action such as pressing "Cancel"
  1960 ** or Ctrl-C where the user wants a long query operation to halt
  1961 ** immediately.
  1962 **
  1963 ** ^It is safe to call this routine from a thread different from the
  1964 ** thread that is currently running the database operation.  But it
  1965 ** is not safe to call this routine with a [database connection] that
  1966 ** is closed or might close before sqlite3_interrupt() returns.
  1967 **
  1968 ** ^If an SQL operation is very nearly finished at the time when
  1969 ** sqlite3_interrupt() is called, then it might not have an opportunity
  1970 ** to be interrupted and might continue to completion.
  1971 **
  1972 ** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
  1973 ** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
  1974 ** that is inside an explicit transaction, then the entire transaction
  1975 ** will be rolled back automatically.
  1976 **
  1977 ** ^The sqlite3_interrupt(D) call is in effect until all currently running
  1978 ** SQL statements on [database connection] D complete.  ^Any new SQL statements
  1979 ** that are started after the sqlite3_interrupt() call and before the 
  1980 ** running statements reaches zero are interrupted as if they had been
  1981 ** running prior to the sqlite3_interrupt() call.  ^New SQL statements
  1982 ** that are started after the running statement count reaches zero are
  1983 ** not effected by the sqlite3_interrupt().
  1984 ** ^A call to sqlite3_interrupt(D) that occurs when there are no running
  1985 ** SQL statements is a no-op and has no effect on SQL statements
  1986 ** that are started after the sqlite3_interrupt() call returns.
  1987 **
  1988 ** If the database connection closes while [sqlite3_interrupt()]
  1989 ** is running then bad things will likely happen.
  1990 */
  1991 SQLITE_API void sqlite3_interrupt(sqlite3*);
  1992 
  1993 /*
  1994 ** CAPI3REF: Determine If An SQL Statement Is Complete
  1995 **
  1996 ** These routines are useful during command-line input to determine if the
  1997 ** currently entered text seems to form a complete SQL statement or
  1998 ** if additional input is needed before sending the text into
  1999 ** SQLite for parsing.  ^These routines return 1 if the input string
  2000 ** appears to be a complete SQL statement.  ^A statement is judged to be
  2001 ** complete if it ends with a semicolon token and is not a prefix of a
  2002 ** well-formed CREATE TRIGGER statement.  ^Semicolons that are embedded within
  2003 ** string literals or quoted identifier names or comments are not
  2004 ** independent tokens (they are part of the token in which they are
  2005 ** embedded) and thus do not count as a statement terminator.  ^Whitespace
  2006 ** and comments that follow the final semicolon are ignored.
  2007 **
  2008 ** ^These routines return 0 if the statement is incomplete.  ^If a
  2009 ** memory allocation fails, then SQLITE_NOMEM is returned.
  2010 **
  2011 ** ^These routines do not parse the SQL statements thus
  2012 ** will not detect syntactically incorrect SQL.
  2013 **
  2014 ** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior 
  2015 ** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked
  2016 ** automatically by sqlite3_complete16().  If that initialization fails,
  2017 ** then the return value from sqlite3_complete16() will be non-zero
  2018 ** regardless of whether or not the input SQL is complete.)^
  2019 **
  2020 ** The input to [sqlite3_complete()] must be a zero-terminated
  2021 ** UTF-8 string.
  2022 **
  2023 ** The input to [sqlite3_complete16()] must be a zero-terminated
  2024 ** UTF-16 string in native byte order.
  2025 */
  2026 SQLITE_API int sqlite3_complete(const char *sql);
  2027 SQLITE_API int sqlite3_complete16(const void *sql);
  2028 
  2029 /*
  2030 ** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
  2031 **
  2032 ** ^The sqlite3_busy_handler(D,X,P) routine sets a callback function X
  2033 ** that might be invoked with argument P whenever
  2034 ** an attempt is made to access a database table associated with
  2035 ** [database connection] D when another thread
  2036 ** or process has the table locked.
  2037 ** The sqlite3_busy_handler() interface is used to implement
  2038 ** [sqlite3_busy_timeout()] and [PRAGMA busy_timeout].
  2039 **
  2040 ** ^If the busy callback is NULL, then [SQLITE_BUSY]
  2041 ** is returned immediately upon encountering the lock.  ^If the busy callback
  2042 ** is not NULL, then the callback might be invoked with two arguments.
  2043 **
  2044 ** ^The first argument to the busy handler is a copy of the void* pointer which
  2045 ** is the third argument to sqlite3_busy_handler().  ^The second argument to
  2046 ** the busy handler callback is the number of times that the busy handler has
  2047 ** been invoked for the same locking event.  ^If the
  2048 ** busy callback returns 0, then no additional attempts are made to
  2049 ** access the database and [SQLITE_BUSY] is returned
  2050 ** to the application.
  2051 ** ^If the callback returns non-zero, then another attempt
  2052 ** is made to access the database and the cycle repeats.
  2053 **
  2054 ** The presence of a busy handler does not guarantee that it will be invoked
  2055 ** when there is lock contention. ^If SQLite determines that invoking the busy
  2056 ** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
  2057 ** to the application instead of invoking the 
  2058 ** busy handler.
  2059 ** Consider a scenario where one process is holding a read lock that
  2060 ** it is trying to promote to a reserved lock and
  2061 ** a second process is holding a reserved lock that it is trying
  2062 ** to promote to an exclusive lock.  The first process cannot proceed
  2063 ** because it is blocked by the second and the second process cannot
  2064 ** proceed because it is blocked by the first.  If both processes
  2065 ** invoke the busy handlers, neither will make any progress.  Therefore,
  2066 ** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
  2067 ** will induce the first process to release its read lock and allow
  2068 ** the second process to proceed.
  2069 **
  2070 ** ^The default busy callback is NULL.
  2071 **
  2072 ** ^(There can only be a single busy handler defined for each
  2073 ** [database connection].  Setting a new busy handler clears any
  2074 ** previously set handler.)^  ^Note that calling [sqlite3_busy_timeout()]
  2075 ** or evaluating [PRAGMA busy_timeout=N] will change the
  2076 ** busy handler and thus clear any previously set busy handler.
  2077 **
  2078 ** The busy callback should not take any actions which modify the
  2079 ** database connection that invoked the busy handler.  In other words,
  2080 ** the busy handler is not reentrant.  Any such actions
  2081 ** result in undefined behavior.
  2082 ** 
  2083 ** A busy handler must not close the database connection
  2084 ** or [prepared statement] that invoked the busy handler.
  2085 */
  2086 SQLITE_API int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);
  2087 
  2088 /*
  2089 ** CAPI3REF: Set A Busy Timeout
  2090 **
  2091 ** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
  2092 ** for a specified amount of time when a table is locked.  ^The handler
  2093 ** will sleep multiple times until at least "ms" milliseconds of sleeping
  2094 ** have accumulated.  ^After at least "ms" milliseconds of sleeping,
  2095 ** the handler returns 0 which causes [sqlite3_step()] to return
  2096 ** [SQLITE_BUSY].
  2097 **
  2098 ** ^Calling this routine with an argument less than or equal to zero
  2099 ** turns off all busy handlers.
  2100 **
  2101 ** ^(There can only be a single busy handler for a particular
  2102 ** [database connection] any any given moment.  If another busy handler
  2103 ** was defined  (using [sqlite3_busy_handler()]) prior to calling
  2104 ** this routine, that other busy handler is cleared.)^
  2105 **
  2106 ** See also:  [PRAGMA busy_timeout]
  2107 */
  2108 SQLITE_API int sqlite3_busy_timeout(sqlite3*, int ms);
  2109 
  2110 /*
  2111 ** CAPI3REF: Convenience Routines For Running Queries
  2112 **
  2113 ** This is a legacy interface that is preserved for backwards compatibility.
  2114 ** Use of this interface is not recommended.
  2115 **
  2116 ** Definition: A <b>result table</b> is memory data structure created by the
  2117 ** [sqlite3_get_table()] interface.  A result table records the
  2118 ** complete query results from one or more queries.
  2119 **
  2120 ** The table conceptually has a number of rows and columns.  But
  2121 ** these numbers are not part of the result table itself.  These
  2122 ** numbers are obtained separately.  Let N be the number of rows
  2123 ** and M be the number of columns.
  2124 **
  2125 ** A result table is an array of pointers to zero-terminated UTF-8 strings.
  2126 ** There are (N+1)*M elements in the array.  The first M pointers point
  2127 ** to zero-terminated strings that  contain the names of the columns.
  2128 ** The remaining entries all point to query results.  NULL values result
  2129 ** in NULL pointers.  All other values are in their UTF-8 zero-terminated
  2130 ** string representation as returned by [sqlite3_column_text()].
  2131 **
  2132 ** A result table might consist of one or more memory allocations.
  2133 ** It is not safe to pass a result table directly to [sqlite3_free()].
  2134 ** A result table should be deallocated using [sqlite3_free_table()].
  2135 **
  2136 ** ^(As an example of the result table format, suppose a query result
  2137 ** is as follows:
  2138 **
  2139 ** <blockquote><pre>
  2140 **        Name        | Age
  2141 **        -----------------------
  2142 **        Alice       | 43
  2143 **        Bob         | 28
  2144 **        Cindy       | 21
  2145 ** </pre></blockquote>
  2146 **
  2147 ** There are two column (M==2) and three rows (N==3).  Thus the
  2148 ** result table has 8 entries.  Suppose the result table is stored
  2149 ** in an array names azResult.  Then azResult holds this content:
  2150 **
  2151 ** <blockquote><pre>
  2152 **        azResult&#91;0] = "Name";
  2153 **        azResult&#91;1] = "Age";
  2154 **        azResult&#91;2] = "Alice";
  2155 **        azResult&#91;3] = "43";
  2156 **        azResult&#91;4] = "Bob";
  2157 **        azResult&#91;5] = "28";
  2158 **        azResult&#91;6] = "Cindy";
  2159 **        azResult&#91;7] = "21";
  2160 ** </pre></blockquote>)^
  2161 **
  2162 ** ^The sqlite3_get_table() function evaluates one or more
  2163 ** semicolon-separated SQL statements in the zero-terminated UTF-8
  2164 ** string of its 2nd parameter and returns a result table to the
  2165 ** pointer given in its 3rd parameter.
  2166 **
  2167 ** After the application has finished with the result from sqlite3_get_table(),
  2168 ** it must pass the result table pointer to sqlite3_free_table() in order to
  2169 ** release the memory that was malloced.  Because of the way the
  2170 ** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
  2171 ** function must not try to call [sqlite3_free()] directly.  Only
  2172 ** [sqlite3_free_table()] is able to release the memory properly and safely.
  2173 **
  2174 ** The sqlite3_get_table() interface is implemented as a wrapper around
  2175 ** [sqlite3_exec()].  The sqlite3_get_table() routine does not have access
  2176 ** to any internal data structures of SQLite.  It uses only the public
  2177 ** interface defined here.  As a consequence, errors that occur in the
  2178 ** wrapper layer outside of the internal [sqlite3_exec()] call are not
  2179 ** reflected in subsequent calls to [sqlite3_errcode()] or
  2180 ** [sqlite3_errmsg()].
  2181 */
  2182 SQLITE_API int sqlite3_get_table(
  2183   sqlite3 *db,          /* An open database */
  2184   const char *zSql,     /* SQL to be evaluated */
  2185   char ***pazResult,    /* Results of the query */
  2186   int *pnRow,           /* Number of result rows written here */
  2187   int *pnColumn,        /* Number of result columns written here */
  2188   char **pzErrmsg       /* Error msg written here */
  2189 );
  2190 SQLITE_API void sqlite3_free_table(char **result);
  2191 
  2192 /*
  2193 ** CAPI3REF: Formatted String Printing Functions
  2194 **
  2195 ** These routines are work-alikes of the "printf()" family of functions
  2196 ** from the standard C library.
  2197 **
  2198 ** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
  2199 ** results into memory obtained from [sqlite3_malloc()].
  2200 ** The strings returned by these two routines should be
  2201 ** released by [sqlite3_free()].  ^Both routines return a
  2202 ** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
  2203 ** memory to hold the resulting string.
  2204 **
  2205 ** ^(The sqlite3_snprintf() routine is similar to "snprintf()" from
  2206 ** the standard C library.  The result is written into the
  2207 ** buffer supplied as the second parameter whose size is given by
  2208 ** the first parameter. Note that the order of the
  2209 ** first two parameters is reversed from snprintf().)^  This is an
  2210 ** historical accident that cannot be fixed without breaking
  2211 ** backwards compatibility.  ^(Note also that sqlite3_snprintf()
  2212 ** returns a pointer to its buffer instead of the number of
  2213 ** characters actually written into the buffer.)^  We admit that
  2214 ** the number of characters written would be a more useful return
  2215 ** value but we cannot change the implementation of sqlite3_snprintf()
  2216 ** now without breaking compatibility.
  2217 **
  2218 ** ^As long as the buffer size is greater than zero, sqlite3_snprintf()
  2219 ** guarantees that the buffer is always zero-terminated.  ^The first
  2220 ** parameter "n" is the total size of the buffer, including space for
  2221 ** the zero terminator.  So the longest string that can be completely
  2222 ** written will be n-1 characters.
  2223 **
  2224 ** ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf().
  2225 **
  2226 ** These routines all implement some additional formatting
  2227 ** options that are useful for constructing SQL statements.
  2228 ** All of the usual printf() formatting options apply.  In addition, there
  2229 ** is are "%q", "%Q", and "%z" options.
  2230 **
  2231 ** ^(The %q option works like %s in that it substitutes a nul-terminated
  2232 ** string from the argument list.  But %q also doubles every '\'' character.
  2233 ** %q is designed for use inside a string literal.)^  By doubling each '\''
  2234 ** character it escapes that character and allows it to be inserted into
  2235 ** the string.
  2236 **
  2237 ** For example, assume the string variable zText contains text as follows:
  2238 **
  2239 ** <blockquote><pre>
  2240 **  char *zText = "It's a happy day!";
  2241 ** </pre></blockquote>
  2242 **
  2243 ** One can use this text in an SQL statement as follows:
  2244 **
  2245 ** <blockquote><pre>
  2246 **  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);
  2247 **  sqlite3_exec(db, zSQL, 0, 0, 0);
  2248 **  sqlite3_free(zSQL);
  2249 ** </pre></blockquote>
  2250 **
  2251 ** Because the %q format string is used, the '\'' character in zText
  2252 ** is escaped and the SQL generated is as follows:
  2253 **
  2254 ** <blockquote><pre>
  2255 **  INSERT INTO table1 VALUES('It''s a happy day!')
  2256 ** </pre></blockquote>
  2257 **
  2258 ** This is correct.  Had we used %s instead of %q, the generated SQL
  2259 ** would have looked like this:
  2260 **
  2261 ** <blockquote><pre>
  2262 **  INSERT INTO table1 VALUES('It's a happy day!');
  2263 ** </pre></blockquote>
  2264 **
  2265 ** This second example is an SQL syntax error.  As a general rule you should
  2266 ** always use %q instead of %s when inserting text into a string literal.
  2267 **
  2268 ** ^(The %Q option works like %q except it also adds single quotes around
  2269 ** the outside of the total string.  Additionally, if the parameter in the
  2270 ** argument list is a NULL pointer, %Q substitutes the text "NULL" (without
  2271 ** single quotes).)^  So, for example, one could say:
  2272 **
  2273 ** <blockquote><pre>
  2274 **  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);
  2275 **  sqlite3_exec(db, zSQL, 0, 0, 0);
  2276 **  sqlite3_free(zSQL);
  2277 ** </pre></blockquote>
  2278 **
  2279 ** The code above will render a correct SQL statement in the zSQL
  2280 ** variable even if the zText variable is a NULL pointer.
  2281 **
  2282 ** ^(The "%z" formatting option works like "%s" but with the
  2283 ** addition that after the string has been read and copied into
  2284 ** the result, [sqlite3_free()] is called on the input string.)^
  2285 */
  2286 SQLITE_API char *sqlite3_mprintf(const char*,...);
  2287 SQLITE_API char *sqlite3_vmprintf(const char*, va_list);
  2288 SQLITE_API char *sqlite3_snprintf(int,char*,const char*, ...);
  2289 SQLITE_API char *sqlite3_vsnprintf(int,char*,const char*, va_list);
  2290 
  2291 /*
  2292 ** CAPI3REF: Memory Allocation Subsystem
  2293 **
  2294 ** The SQLite core uses these three routines for all of its own
  2295 ** internal memory allocation needs. "Core" in the previous sentence
  2296 ** does not include operating-system specific VFS implementation.  The
  2297 ** Windows VFS uses native malloc() and free() for some operations.
  2298 **
  2299 ** ^The sqlite3_malloc() routine returns a pointer to a block
  2300 ** of memory at least N bytes in length, where N is the parameter.
  2301 ** ^If sqlite3_malloc() is unable to obtain sufficient free
  2302 ** memory, it returns a NULL pointer.  ^If the parameter N to
  2303 ** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
  2304 ** a NULL pointer.
  2305 **
  2306 ** ^Calling sqlite3_free() with a pointer previously returned
  2307 ** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
  2308 ** that it might be reused.  ^The sqlite3_free() routine is
  2309 ** a no-op if is called with a NULL pointer.  Passing a NULL pointer
  2310 ** to sqlite3_free() is harmless.  After being freed, memory
  2311 ** should neither be read nor written.  Even reading previously freed
  2312 ** memory might result in a segmentation fault or other severe error.
  2313 ** Memory corruption, a segmentation fault, or other severe error
  2314 ** might result if sqlite3_free() is called with a non-NULL pointer that
  2315 ** was not obtained from sqlite3_malloc() or sqlite3_realloc().
  2316 **
  2317 ** ^(The sqlite3_realloc() interface attempts to resize a
  2318 ** prior memory allocation to be at least N bytes, where N is the
  2319 ** second parameter.  The memory allocation to be resized is the first
  2320 ** parameter.)^ ^ If the first parameter to sqlite3_realloc()
  2321 ** is a NULL pointer then its behavior is identical to calling
  2322 ** sqlite3_malloc(N) where N is the second parameter to sqlite3_realloc().
  2323 ** ^If the second parameter to sqlite3_realloc() is zero or
  2324 ** negative then the behavior is exactly the same as calling
  2325 ** sqlite3_free(P) where P is the first parameter to sqlite3_realloc().
  2326 ** ^sqlite3_realloc() returns a pointer to a memory allocation
  2327 ** of at least N bytes in size or NULL if sufficient memory is unavailable.
  2328 ** ^If M is the size of the prior allocation, then min(N,M) bytes
  2329 ** of the prior allocation are copied into the beginning of buffer returned
  2330 ** by sqlite3_realloc() and the prior allocation is freed.
  2331 ** ^If sqlite3_realloc() returns NULL, then the prior allocation
  2332 ** is not freed.
  2333 **
  2334 ** ^The memory returned by sqlite3_malloc() and sqlite3_realloc()
  2335 ** is always aligned to at least an 8 byte boundary, or to a
  2336 ** 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time
  2337 ** option is used.
  2338 **
  2339 ** In SQLite version 3.5.0 and 3.5.1, it was possible to define
  2340 ** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
  2341 ** implementation of these routines to be omitted.  That capability
  2342 ** is no longer provided.  Only built-in memory allocators can be used.
  2343 **
  2344 ** Prior to SQLite version 3.7.10, the Windows OS interface layer called
  2345 ** the system malloc() and free() directly when converting
  2346 ** filenames between the UTF-8 encoding used by SQLite
  2347 ** and whatever filename encoding is used by the particular Windows
  2348 ** installation.  Memory allocation errors were detected, but
  2349 ** they were reported back as [SQLITE_CANTOPEN] or
  2350 ** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
  2351 **
  2352 ** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
  2353 ** must be either NULL or else pointers obtained from a prior
  2354 ** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
  2355 ** not yet been released.
  2356 **
  2357 ** The application must not read or write any part of
  2358 ** a block of memory after it has been released using
  2359 ** [sqlite3_free()] or [sqlite3_realloc()].
  2360 */
  2361 SQLITE_API void *sqlite3_malloc(int);
  2362 SQLITE_API void *sqlite3_realloc(void*, int);
  2363 SQLITE_API void sqlite3_free(void*);
  2364 
  2365 /*
  2366 ** CAPI3REF: Memory Allocator Statistics
  2367 **
  2368 ** SQLite provides these two interfaces for reporting on the status
  2369 ** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
  2370 ** routines, which form the built-in memory allocation subsystem.
  2371 **
  2372 ** ^The [sqlite3_memory_used()] routine returns the number of bytes
  2373 ** of memory currently outstanding (malloced but not freed).
  2374 ** ^The [sqlite3_memory_highwater()] routine returns the maximum
  2375 ** value of [sqlite3_memory_used()] since the high-water mark
  2376 ** was last reset.  ^The values returned by [sqlite3_memory_used()] and
  2377 ** [sqlite3_memory_highwater()] include any overhead
  2378 ** added by SQLite in its implementation of [sqlite3_malloc()],
  2379 ** but not overhead added by the any underlying system library
  2380 ** routines that [sqlite3_malloc()] may call.
  2381 **
  2382 ** ^The memory high-water mark is reset to the current value of
  2383 ** [sqlite3_memory_used()] if and only if the parameter to
  2384 ** [sqlite3_memory_highwater()] is true.  ^The value returned
  2385 ** by [sqlite3_memory_highwater(1)] is the high-water mark
  2386 ** prior to the reset.
  2387 */
  2388 SQLITE_API sqlite3_int64 sqlite3_memory_used(void);
  2389 SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag);
  2390 
  2391 /*
  2392 ** CAPI3REF: Pseudo-Random Number Generator
  2393 **
  2394 ** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
  2395 ** select random [ROWID | ROWIDs] when inserting new records into a table that
  2396 ** already uses the largest possible [ROWID].  The PRNG is also used for
  2397 ** the build-in random() and randomblob() SQL functions.  This interface allows
  2398 ** applications to access the same PRNG for other purposes.
  2399 **
  2400 ** ^A call to this routine stores N bytes of randomness into buffer P.
  2401 ** ^If N is less than one, then P can be a NULL pointer.
  2402 **
  2403 ** ^If this routine has not been previously called or if the previous
  2404 ** call had N less than one, then the PRNG is seeded using randomness
  2405 ** obtained from the xRandomness method of the default [sqlite3_vfs] object.
  2406 ** ^If the previous call to this routine had an N of 1 or more then
  2407 ** the pseudo-randomness is generated
  2408 ** internally and without recourse to the [sqlite3_vfs] xRandomness
  2409 ** method.
  2410 */
  2411 SQLITE_API void sqlite3_randomness(int N, void *P);
  2412 
  2413 /*
  2414 ** CAPI3REF: Compile-Time Authorization Callbacks
  2415 **
  2416 ** ^This routine registers an authorizer callback with a particular
  2417 ** [database connection], supplied in the first argument.
  2418 ** ^The authorizer callback is invoked as SQL statements are being compiled
  2419 ** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
  2420 ** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()].  ^At various
  2421 ** points during the compilation process, as logic is being created
  2422 ** to perform various actions, the authorizer callback is invoked to
  2423 ** see if those actions are allowed.  ^The authorizer callback should
  2424 ** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
  2425 ** specific action but allow the SQL statement to continue to be
  2426 ** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
  2427 ** rejected with an error.  ^If the authorizer callback returns
  2428 ** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
  2429 ** then the [sqlite3_prepare_v2()] or equivalent call that triggered
  2430 ** the authorizer will fail with an error message.
  2431 **
  2432 ** When the callback returns [SQLITE_OK], that means the operation
  2433 ** requested is ok.  ^When the callback returns [SQLITE_DENY], the
  2434 ** [sqlite3_prepare_v2()] or equivalent call that triggered the
  2435 ** authorizer will fail with an error message explaining that
  2436 ** access is denied. 
  2437 **
  2438 ** ^The first parameter to the authorizer callback is a copy of the third
  2439 ** parameter to the sqlite3_set_authorizer() interface. ^The second parameter
  2440 ** to the callback is an integer [SQLITE_COPY | action code] that specifies
  2441 ** the particular action to be authorized. ^The third through sixth parameters
  2442 ** to the callback are zero-terminated strings that contain additional
  2443 ** details about the action to be authorized.
  2444 **
  2445 ** ^If the action code is [SQLITE_READ]
  2446 ** and the callback returns [SQLITE_IGNORE] then the
  2447 ** [prepared statement] statement is constructed to substitute
  2448 ** a NULL value in place of the table column that would have
  2449 ** been read if [SQLITE_OK] had been returned.  The [SQLITE_IGNORE]
  2450 ** return can be used to deny an untrusted user access to individual
  2451 ** columns of a table.
  2452 ** ^If the action code is [SQLITE_DELETE] and the callback returns
  2453 ** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the
  2454 ** [truncate optimization] is disabled and all rows are deleted individually.
  2455 **
  2456 ** An authorizer is used when [sqlite3_prepare | preparing]
  2457 ** SQL statements from an untrusted source, to ensure that the SQL statements
  2458 ** do not try to access data they are not allowed to see, or that they do not
  2459 ** try to execute malicious statements that damage the database.  For
  2460 ** example, an application may allow a user to enter arbitrary
  2461 ** SQL queries for evaluation by a database.  But the application does
  2462 ** not want the user to be able to make arbitrary changes to the
  2463 ** database.  An authorizer could then be put in place while the
  2464 ** user-entered SQL is being [sqlite3_prepare | prepared] that
  2465 ** disallows everything except [SELECT] statements.
  2466 **
  2467 ** Applications that need to process SQL from untrusted sources
  2468 ** might also consider lowering resource limits using [sqlite3_limit()]
  2469 ** and limiting database size using the [max_page_count] [PRAGMA]
  2470 ** in addition to using an authorizer.
  2471 **
  2472 ** ^(Only a single authorizer can be in place on a database connection
  2473 ** at a time.  Each call to sqlite3_set_authorizer overrides the
  2474 ** previous call.)^  ^Disable the authorizer by installing a NULL callback.
  2475 ** The authorizer is disabled by default.
  2476 **
  2477 ** The authorizer callback must not do anything that will modify
  2478 ** the database connection that invoked the authorizer callback.
  2479 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  2480 ** database connections for the meaning of "modify" in this paragraph.
  2481 **
  2482 ** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the
  2483 ** statement might be re-prepared during [sqlite3_step()] due to a 
  2484 ** schema change.  Hence, the application should ensure that the
  2485 ** correct authorizer callback remains in place during the [sqlite3_step()].
  2486 **
  2487 ** ^Note that the authorizer callback is invoked only during
  2488 ** [sqlite3_prepare()] or its variants.  Authorization is not
  2489 ** performed during statement evaluation in [sqlite3_step()], unless
  2490 ** as stated in the previous paragraph, sqlite3_step() invokes
  2491 ** sqlite3_prepare_v2() to reprepare a statement after a schema change.
  2492 */
  2493 SQLITE_API int sqlite3_set_authorizer(
  2494   sqlite3*,
  2495   int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
  2496   void *pUserData
  2497 );
  2498 
  2499 /*
  2500 ** CAPI3REF: Authorizer Return Codes
  2501 **
  2502 ** The [sqlite3_set_authorizer | authorizer callback function] must
  2503 ** return either [SQLITE_OK] or one of these two constants in order
  2504 ** to signal SQLite whether or not the action is permitted.  See the
  2505 ** [sqlite3_set_authorizer | authorizer documentation] for additional
  2506 ** information.
  2507 **
  2508 ** Note that SQLITE_IGNORE is also used as a [conflict resolution mode]
  2509 ** returned from the [sqlite3_vtab_on_conflict()] interface.
  2510 */
  2511 #define SQLITE_DENY   1   /* Abort the SQL statement with an error */
  2512 #define SQLITE_IGNORE 2   /* Don't allow access, but don't generate an error */
  2513 
  2514 /*
  2515 ** CAPI3REF: Authorizer Action Codes
  2516 **
  2517 ** The [sqlite3_set_authorizer()] interface registers a callback function
  2518 ** that is invoked to authorize certain SQL statement actions.  The
  2519 ** second parameter to the callback is an integer code that specifies
  2520 ** what action is being authorized.  These are the integer action codes that
  2521 ** the authorizer callback may be passed.
  2522 **
  2523 ** These action code values signify what kind of operation is to be
  2524 ** authorized.  The 3rd and 4th parameters to the authorization
  2525 ** callback function will be parameters or NULL depending on which of these
  2526 ** codes is used as the second parameter.  ^(The 5th parameter to the
  2527 ** authorizer callback is the name of the database ("main", "temp",
  2528 ** etc.) if applicable.)^  ^The 6th parameter to the authorizer callback
  2529 ** is the name of the inner-most trigger or view that is responsible for
  2530 ** the access attempt or NULL if this access attempt is directly from
  2531 ** top-level SQL code.
  2532 */
  2533 /******************************************* 3rd ************ 4th ***********/
  2534 #define SQLITE_CREATE_INDEX          1   /* Index Name      Table Name      */
  2535 #define SQLITE_CREATE_TABLE          2   /* Table Name      NULL            */
  2536 #define SQLITE_CREATE_TEMP_INDEX     3   /* Index Name      Table Name      */
  2537 #define SQLITE_CREATE_TEMP_TABLE     4   /* Table Name      NULL            */
  2538 #define SQLITE_CREATE_TEMP_TRIGGER   5   /* Trigger Name    Table Name      */
  2539 #define SQLITE_CREATE_TEMP_VIEW      6   /* View Name       NULL            */
  2540 #define SQLITE_CREATE_TRIGGER        7   /* Trigger Name    Table Name      */
  2541 #define SQLITE_CREATE_VIEW           8   /* View Name       NULL            */
  2542 #define SQLITE_DELETE                9   /* Table Name      NULL            */
  2543 #define SQLITE_DROP_INDEX           10   /* Index Name      Table Name      */
  2544 #define SQLITE_DROP_TABLE           11   /* Table Name      NULL            */
  2545 #define SQLITE_DROP_TEMP_INDEX      12   /* Index Name      Table Name      */
  2546 #define SQLITE_DROP_TEMP_TABLE      13   /* Table Name      NULL            */
  2547 #define SQLITE_DROP_TEMP_TRIGGER    14   /* Trigger Name    Table Name      */
  2548 #define SQLITE_DROP_TEMP_VIEW       15   /* View Name       NULL            */
  2549 #define SQLITE_DROP_TRIGGER         16   /* Trigger Name    Table Name      */
  2550 #define SQLITE_DROP_VIEW            17   /* View Name       NULL            */
  2551 #define SQLITE_INSERT               18   /* Table Name      NULL            */
  2552 #define SQLITE_PRAGMA               19   /* Pragma Name     1st arg or NULL */
  2553 #define SQLITE_READ                 20   /* Table Name      Column Name     */
  2554 #define SQLITE_SELECT               21   /* NULL            NULL            */
  2555 #define SQLITE_TRANSACTION          22   /* Operation       NULL            */
  2556 #define SQLITE_UPDATE               23   /* Table Name      Column Name     */
  2557 #define SQLITE_ATTACH               24   /* Filename        NULL            */
  2558 #define SQLITE_DETACH               25   /* Database Name   NULL            */
  2559 #define SQLITE_ALTER_TABLE          26   /* Database Name   Table Name      */
  2560 #define SQLITE_REINDEX              27   /* Index Name      NULL            */
  2561 #define SQLITE_ANALYZE              28   /* Table Name      NULL            */
  2562 #define SQLITE_CREATE_VTABLE        29   /* Table Name      Module Name     */
  2563 #define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
  2564 #define SQLITE_FUNCTION             31   /* NULL            Function Name   */
  2565 #define SQLITE_SAVEPOINT            32   /* Operation       Savepoint Name  */
  2566 #define SQLITE_COPY                  0   /* No longer used */
  2567 #define SQLITE_RECURSIVE            33   /* NULL            NULL            */
  2568 
  2569 /*
  2570 ** CAPI3REF: Tracing And Profiling Functions
  2571 **
  2572 ** These routines register callback functions that can be used for
  2573 ** tracing and profiling the execution of SQL statements.
  2574 **
  2575 ** ^The callback function registered by sqlite3_trace() is invoked at
  2576 ** various times when an SQL statement is being run by [sqlite3_step()].
  2577 ** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
  2578 ** SQL statement text as the statement first begins executing.
  2579 ** ^(Additional sqlite3_trace() callbacks might occur
  2580 ** as each triggered subprogram is entered.  The callbacks for triggers
  2581 ** contain a UTF-8 SQL comment that identifies the trigger.)^
  2582 **
  2583 ** The [SQLITE_TRACE_SIZE_LIMIT] compile-time option can be used to limit
  2584 ** the length of [bound parameter] expansion in the output of sqlite3_trace().
  2585 **
  2586 ** ^The callback function registered by sqlite3_profile() is invoked
  2587 ** as each SQL statement finishes.  ^The profile callback contains
  2588 ** the original statement text and an estimate of wall-clock time
  2589 ** of how long that statement took to run.  ^The profile callback
  2590 ** time is in units of nanoseconds, however the current implementation
  2591 ** is only capable of millisecond resolution so the six least significant
  2592 ** digits in the time are meaningless.  Future versions of SQLite
  2593 ** might provide greater resolution on the profiler callback.  The
  2594 ** sqlite3_profile() function is considered experimental and is
  2595 ** subject to change in future versions of SQLite.
  2596 */
  2597 SQLITE_API void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*);
  2598 SQLITE_API SQLITE_EXPERIMENTAL void *sqlite3_profile(sqlite3*,
  2599    void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
  2600 
  2601 /*
  2602 ** CAPI3REF: Query Progress Callbacks
  2603 **
  2604 ** ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback
  2605 ** function X to be invoked periodically during long running calls to
  2606 ** [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for
  2607 ** database connection D.  An example use for this
  2608 ** interface is to keep a GUI updated during a large query.
  2609 **
  2610 ** ^The parameter P is passed through as the only parameter to the 
  2611 ** callback function X.  ^The parameter N is the approximate number of 
  2612 ** [virtual machine instructions] that are evaluated between successive
  2613 ** invocations of the callback X.  ^If N is less than one then the progress
  2614 ** handler is disabled.
  2615 **
  2616 ** ^Only a single progress handler may be defined at one time per
  2617 ** [database connection]; setting a new progress handler cancels the
  2618 ** old one.  ^Setting parameter X to NULL disables the progress handler.
  2619 ** ^The progress handler is also disabled by setting N to a value less
  2620 ** than 1.
  2621 **
  2622 ** ^If the progress callback returns non-zero, the operation is
  2623 ** interrupted.  This feature can be used to implement a
  2624 ** "Cancel" button on a GUI progress dialog box.
  2625 **
  2626 ** The progress handler callback must not do anything that will modify
  2627 ** the database connection that invoked the progress handler.
  2628 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  2629 ** database connections for the meaning of "modify" in this paragraph.
  2630 **
  2631 */
  2632 SQLITE_API void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
  2633 
  2634 /*
  2635 ** CAPI3REF: Opening A New Database Connection
  2636 **
  2637 ** ^These routines open an SQLite database file as specified by the 
  2638 ** filename argument. ^The filename argument is interpreted as UTF-8 for
  2639 ** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
  2640 ** order for sqlite3_open16(). ^(A [database connection] handle is usually
  2641 ** returned in *ppDb, even if an error occurs.  The only exception is that
  2642 ** if SQLite is unable to allocate memory to hold the [sqlite3] object,
  2643 ** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
  2644 ** object.)^ ^(If the database is opened (and/or created) successfully, then
  2645 ** [SQLITE_OK] is returned.  Otherwise an [error code] is returned.)^ ^The
  2646 ** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
  2647 ** an English language description of the error following a failure of any
  2648 ** of the sqlite3_open() routines.
  2649 **
  2650 ** ^The default encoding for the database will be UTF-8 if
  2651 ** sqlite3_open() or sqlite3_open_v2() is called and
  2652 ** UTF-16 in the native byte order if sqlite3_open16() is used.
  2653 **
  2654 ** Whether or not an error occurs when it is opened, resources
  2655 ** associated with the [database connection] handle should be released by
  2656 ** passing it to [sqlite3_close()] when it is no longer required.
  2657 **
  2658 ** The sqlite3_open_v2() interface works like sqlite3_open()
  2659 ** except that it accepts two additional parameters for additional control
  2660 ** over the new database connection.  ^(The flags parameter to
  2661 ** sqlite3_open_v2() can take one of
  2662 ** the following three values, optionally combined with the 
  2663 ** [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE],
  2664 ** [SQLITE_OPEN_PRIVATECACHE], and/or [SQLITE_OPEN_URI] flags:)^
  2665 **
  2666 ** <dl>
  2667 ** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
  2668 ** <dd>The database is opened in read-only mode.  If the database does not
  2669 ** already exist, an error is returned.</dd>)^
  2670 **
  2671 ** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
  2672 ** <dd>The database is opened for reading and writing if possible, or reading
  2673 ** only if the file is write protected by the operating system.  In either
  2674 ** case the database must already exist, otherwise an error is returned.</dd>)^
  2675 **
  2676 ** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
  2677 ** <dd>The database is opened for reading and writing, and is created if
  2678 ** it does not already exist. This is the behavior that is always used for
  2679 ** sqlite3_open() and sqlite3_open16().</dd>)^
  2680 ** </dl>
  2681 **
  2682 ** If the 3rd parameter to sqlite3_open_v2() is not one of the
  2683 ** combinations shown above optionally combined with other
  2684 ** [SQLITE_OPEN_READONLY | SQLITE_OPEN_* bits]
  2685 ** then the behavior is undefined.
  2686 **
  2687 ** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
  2688 ** opens in the multi-thread [threading mode] as long as the single-thread
  2689 ** mode has not been set at compile-time or start-time.  ^If the
  2690 ** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
  2691 ** in the serialized [threading mode] unless single-thread was
  2692 ** previously selected at compile-time or start-time.
  2693 ** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be
  2694 ** eligible to use [shared cache mode], regardless of whether or not shared
  2695 ** cache is enabled using [sqlite3_enable_shared_cache()].  ^The
  2696 ** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not
  2697 ** participate in [shared cache mode] even if it is enabled.
  2698 **
  2699 ** ^The fourth parameter to sqlite3_open_v2() is the name of the
  2700 ** [sqlite3_vfs] object that defines the operating system interface that
  2701 ** the new database connection should use.  ^If the fourth parameter is
  2702 ** a NULL pointer then the default [sqlite3_vfs] object is used.
  2703 **
  2704 ** ^If the filename is ":memory:", then a private, temporary in-memory database
  2705 ** is created for the connection.  ^This in-memory database will vanish when
  2706 ** the database connection is closed.  Future versions of SQLite might
  2707 ** make use of additional special filenames that begin with the ":" character.
  2708 ** It is recommended that when a database filename actually does begin with
  2709 ** a ":" character you should prefix the filename with a pathname such as
  2710 ** "./" to avoid ambiguity.
  2711 **
  2712 ** ^If the filename is an empty string, then a private, temporary
  2713 ** on-disk database will be created.  ^This private database will be
  2714 ** automatically deleted as soon as the database connection is closed.
  2715 **
  2716 ** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
  2717 **
  2718 ** ^If [URI filename] interpretation is enabled, and the filename argument
  2719 ** begins with "file:", then the filename is interpreted as a URI. ^URI
  2720 ** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
  2721 ** set in the fourth argument to sqlite3_open_v2(), or if it has
  2722 ** been enabled globally using the [SQLITE_CONFIG_URI] option with the
  2723 ** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
  2724 ** As of SQLite version 3.7.7, URI filename interpretation is turned off
  2725 ** by default, but future releases of SQLite might enable URI filename
  2726 ** interpretation by default.  See "[URI filenames]" for additional
  2727 ** information.
  2728 **
  2729 ** URI filenames are parsed according to RFC 3986. ^If the URI contains an
  2730 ** authority, then it must be either an empty string or the string 
  2731 ** "localhost". ^If the authority is not an empty string or "localhost", an 
  2732 ** error is returned to the caller. ^The fragment component of a URI, if 
  2733 ** present, is ignored.
  2734 **
  2735 ** ^SQLite uses the path component of the URI as the name of the disk file
  2736 ** which contains the database. ^If the path begins with a '/' character, 
  2737 ** then it is interpreted as an absolute path. ^If the path does not begin 
  2738 ** with a '/' (meaning that the authority section is omitted from the URI)
  2739 ** then the path is interpreted as a relative path. 
  2740 ** ^On windows, the first component of an absolute path 
  2741 ** is a drive specification (e.g. "C:").
  2742 **
  2743 ** [[core URI query parameters]]
  2744 ** The query component of a URI may contain parameters that are interpreted
  2745 ** either by SQLite itself, or by a [VFS | custom VFS implementation].
  2746 ** SQLite interprets the following three query parameters:
  2747 **
  2748 ** <ul>
  2749 **   <li> <b>vfs</b>: ^The "vfs" parameter may be used to specify the name of
  2750 **     a VFS object that provides the operating system interface that should
  2751 **     be used to access the database file on disk. ^If this option is set to
  2752 **     an empty string the default VFS object is used. ^Specifying an unknown
  2753 **     VFS is an error. ^If sqlite3_open_v2() is used and the vfs option is
  2754 **     present, then the VFS specified by the option takes precedence over
  2755 **     the value passed as the fourth parameter to sqlite3_open_v2().
  2756 **
  2757 **   <li> <b>mode</b>: ^(The mode parameter may be set to either "ro", "rw",
  2758 **     "rwc", or "memory". Attempting to set it to any other value is
  2759 **     an error)^. 
  2760 **     ^If "ro" is specified, then the database is opened for read-only 
  2761 **     access, just as if the [SQLITE_OPEN_READONLY] flag had been set in the 
  2762 **     third argument to sqlite3_open_v2(). ^If the mode option is set to 
  2763 **     "rw", then the database is opened for read-write (but not create) 
  2764 **     access, as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had 
  2765 **     been set. ^Value "rwc" is equivalent to setting both 
  2766 **     SQLITE_OPEN_READWRITE and SQLITE_OPEN_CREATE.  ^If the mode option is
  2767 **     set to "memory" then a pure [in-memory database] that never reads
  2768 **     or writes from disk is used. ^It is an error to specify a value for
  2769 **     the mode parameter that is less restrictive than that specified by
  2770 **     the flags passed in the third parameter to sqlite3_open_v2().
  2771 **
  2772 **   <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or
  2773 **     "private". ^Setting it to "shared" is equivalent to setting the
  2774 **     SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to
  2775 **     sqlite3_open_v2(). ^Setting the cache parameter to "private" is 
  2776 **     equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit.
  2777 **     ^If sqlite3_open_v2() is used and the "cache" parameter is present in
  2778 **     a URI filename, its value overrides any behavior requested by setting
  2779 **     SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag.
  2780 **
  2781 **  <li> <b>psow</b>: ^The psow parameter may be "true" (or "on" or "yes" or
  2782 **     "1") or "false" (or "off" or "no" or "0") to indicate that the
  2783 **     [powersafe overwrite] property does or does not apply to the
  2784 **     storage media on which the database file resides.  ^The psow query
  2785 **     parameter only works for the built-in unix and Windows VFSes.
  2786 **
  2787 **  <li> <b>nolock</b>: ^The nolock parameter is a boolean query parameter
  2788 **     which if set disables file locking in rollback journal modes.  This
  2789 **     is useful for accessing a database on a filesystem that does not
  2790 **     support locking.  Caution:  Database corruption might result if two
  2791 **     or more processes write to the same database and any one of those
  2792 **     processes uses nolock=1.
  2793 **
  2794 **  <li> <b>immutable</b>: ^The immutable parameter is a boolean query
  2795 **     parameter that indicates that the database file is stored on
  2796 **     read-only media.  ^When immutable is set, SQLite assumes that the
  2797 **     database file cannot be changed, even by a process with higher
  2798 **     privilege, and so the database is opened read-only and all locking
  2799 **     and change detection is disabled.  Caution: Setting the immutable
  2800 **     property on a database file that does in fact change can result
  2801 **     in incorrect query results and/or [SQLITE_CORRUPT] errors.
  2802 **     See also: [SQLITE_IOCAP_IMMUTABLE].
  2803 **       
  2804 ** </ul>
  2805 **
  2806 ** ^Specifying an unknown parameter in the query component of a URI is not an
  2807 ** error.  Future versions of SQLite might understand additional query
  2808 ** parameters.  See "[query parameters with special meaning to SQLite]" for
  2809 ** additional information.
  2810 **
  2811 ** [[URI filename examples]] <h3>URI filename examples</h3>
  2812 **
  2813 ** <table border="1" align=center cellpadding=5>
  2814 ** <tr><th> URI filenames <th> Results
  2815 ** <tr><td> file:data.db <td> 
  2816 **          Open the file "data.db" in the current directory.
  2817 ** <tr><td> file:/home/fred/data.db<br>
  2818 **          file:///home/fred/data.db <br> 
  2819 **          file://localhost/home/fred/data.db <br> <td> 
  2820 **          Open the database file "/home/fred/data.db".
  2821 ** <tr><td> file://darkstar/home/fred/data.db <td> 
  2822 **          An error. "darkstar" is not a recognized authority.
  2823 ** <tr><td style="white-space:nowrap"> 
  2824 **          file:///C:/Documents%20and%20Settings/fred/Desktop/data.db
  2825 **     <td> Windows only: Open the file "data.db" on fred's desktop on drive
  2826 **          C:. Note that the %20 escaping in this example is not strictly 
  2827 **          necessary - space characters can be used literally
  2828 **          in URI filenames.
  2829 ** <tr><td> file:data.db?mode=ro&cache=private <td> 
  2830 **          Open file "data.db" in the current directory for read-only access.
  2831 **          Regardless of whether or not shared-cache mode is enabled by
  2832 **          default, use a private cache.
  2833 ** <tr><td> file:/home/fred/data.db?vfs=unix-dotfile <td>
  2834 **          Open file "/home/fred/data.db". Use the special VFS "unix-dotfile"
  2835 **          that uses dot-files in place of posix advisory locking.
  2836 ** <tr><td> file:data.db?mode=readonly <td> 
  2837 **          An error. "readonly" is not a valid option for the "mode" parameter.
  2838 ** </table>
  2839 **
  2840 ** ^URI hexadecimal escape sequences (%HH) are supported within the path and
  2841 ** query components of a URI. A hexadecimal escape sequence consists of a
  2842 ** percent sign - "%" - followed by exactly two hexadecimal digits 
  2843 ** specifying an octet value. ^Before the path or query components of a
  2844 ** URI filename are interpreted, they are encoded using UTF-8 and all 
  2845 ** hexadecimal escape sequences replaced by a single byte containing the
  2846 ** corresponding octet. If this process generates an invalid UTF-8 encoding,
  2847 ** the results are undefined.
  2848 **
  2849 ** <b>Note to Windows users:</b>  The encoding used for the filename argument
  2850 ** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
  2851 ** codepage is currently defined.  Filenames containing international
  2852 ** characters must be converted to UTF-8 prior to passing them into
  2853 ** sqlite3_open() or sqlite3_open_v2().
  2854 **
  2855 ** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
  2856 ** prior to calling sqlite3_open() or sqlite3_open_v2().  Otherwise, various
  2857 ** features that require the use of temporary files may fail.
  2858 **
  2859 ** See also: [sqlite3_temp_directory]
  2860 */
  2861 SQLITE_API int sqlite3_open(
  2862   const char *filename,   /* Database filename (UTF-8) */
  2863   sqlite3 **ppDb          /* OUT: SQLite db handle */
  2864 );
  2865 SQLITE_API int sqlite3_open16(
  2866   const void *filename,   /* Database filename (UTF-16) */
  2867   sqlite3 **ppDb          /* OUT: SQLite db handle */
  2868 );
  2869 SQLITE_API int sqlite3_open_v2(
  2870   const char *filename,   /* Database filename (UTF-8) */
  2871   sqlite3 **ppDb,         /* OUT: SQLite db handle */
  2872   int flags,              /* Flags */
  2873   const char *zVfs        /* Name of VFS module to use */
  2874 );
  2875 
  2876 /*
  2877 ** CAPI3REF: Obtain Values For URI Parameters
  2878 **
  2879 ** These are utility routines, useful to VFS implementations, that check
  2880 ** to see if a database file was a URI that contained a specific query 
  2881 ** parameter, and if so obtains the value of that query parameter.
  2882 **
  2883 ** If F is the database filename pointer passed into the xOpen() method of 
  2884 ** a VFS implementation when the flags parameter to xOpen() has one or 
  2885 ** more of the [SQLITE_OPEN_URI] or [SQLITE_OPEN_MAIN_DB] bits set and
  2886 ** P is the name of the query parameter, then
  2887 ** sqlite3_uri_parameter(F,P) returns the value of the P
  2888 ** parameter if it exists or a NULL pointer if P does not appear as a 
  2889 ** query parameter on F.  If P is a query parameter of F
  2890 ** has no explicit value, then sqlite3_uri_parameter(F,P) returns
  2891 ** a pointer to an empty string.
  2892 **
  2893 ** The sqlite3_uri_boolean(F,P,B) routine assumes that P is a boolean
  2894 ** parameter and returns true (1) or false (0) according to the value
  2895 ** of P.  The sqlite3_uri_boolean(F,P,B) routine returns true (1) if the
  2896 ** value of query parameter P is one of "yes", "true", or "on" in any
  2897 ** case or if the value begins with a non-zero number.  The 
  2898 ** sqlite3_uri_boolean(F,P,B) routines returns false (0) if the value of
  2899 ** query parameter P is one of "no", "false", or "off" in any case or
  2900 ** if the value begins with a numeric zero.  If P is not a query
  2901 ** parameter on F or if the value of P is does not match any of the
  2902 ** above, then sqlite3_uri_boolean(F,P,B) returns (B!=0).
  2903 **
  2904 ** The sqlite3_uri_int64(F,P,D) routine converts the value of P into a
  2905 ** 64-bit signed integer and returns that integer, or D if P does not
  2906 ** exist.  If the value of P is something other than an integer, then
  2907 ** zero is returned.
  2908 ** 
  2909 ** If F is a NULL pointer, then sqlite3_uri_parameter(F,P) returns NULL and
  2910 ** sqlite3_uri_boolean(F,P,B) returns B.  If F is not a NULL pointer and
  2911 ** is not a database file pathname pointer that SQLite passed into the xOpen
  2912 ** VFS method, then the behavior of this routine is undefined and probably
  2913 ** undesirable.
  2914 */
  2915 SQLITE_API const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam);
  2916 SQLITE_API int sqlite3_uri_boolean(const char *zFile, const char *zParam, int bDefault);
  2917 SQLITE_API sqlite3_int64 sqlite3_uri_int64(const char*, const char*, sqlite3_int64);
  2918 
  2919 
  2920 /*
  2921 ** CAPI3REF: Error Codes And Messages
  2922 **
  2923 ** ^The sqlite3_errcode() interface returns the numeric [result code] or
  2924 ** [extended result code] for the most recent failed sqlite3_* API call
  2925 ** associated with a [database connection]. If a prior API call failed
  2926 ** but the most recent API call succeeded, the return value from
  2927 ** sqlite3_errcode() is undefined.  ^The sqlite3_extended_errcode()
  2928 ** interface is the same except that it always returns the 
  2929 ** [extended result code] even when extended result codes are
  2930 ** disabled.
  2931 **
  2932 ** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
  2933 ** text that describes the error, as either UTF-8 or UTF-16 respectively.
  2934 ** ^(Memory to hold the error message string is managed internally.
  2935 ** The application does not need to worry about freeing the result.
  2936 ** However, the error string might be overwritten or deallocated by
  2937 ** subsequent calls to other SQLite interface functions.)^
  2938 **
  2939 ** ^The sqlite3_errstr() interface returns the English-language text
  2940 ** that describes the [result code], as UTF-8.
  2941 ** ^(Memory to hold the error message string is managed internally
  2942 ** and must not be freed by the application)^.
  2943 **
  2944 ** When the serialized [threading mode] is in use, it might be the
  2945 ** case that a second error occurs on a separate thread in between
  2946 ** the time of the first error and the call to these interfaces.
  2947 ** When that happens, the second error will be reported since these
  2948 ** interfaces always report the most recent result.  To avoid
  2949 ** this, each thread can obtain exclusive use of the [database connection] D
  2950 ** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
  2951 ** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
  2952 ** all calls to the interfaces listed here are completed.
  2953 **
  2954 ** If an interface fails with SQLITE_MISUSE, that means the interface
  2955 ** was invoked incorrectly by the application.  In that case, the
  2956 ** error code and message may or may not be set.
  2957 */
  2958 SQLITE_API int sqlite3_errcode(sqlite3 *db);
  2959 SQLITE_API int sqlite3_extended_errcode(sqlite3 *db);
  2960 SQLITE_API const char *sqlite3_errmsg(sqlite3*);
  2961 SQLITE_API const void *sqlite3_errmsg16(sqlite3*);
  2962 SQLITE_API const char *sqlite3_errstr(int);
  2963 
  2964 /*
  2965 ** CAPI3REF: SQL Statement Object
  2966 ** KEYWORDS: {prepared statement} {prepared statements}
  2967 **
  2968 ** An instance of this object represents a single SQL statement.
  2969 ** This object is variously known as a "prepared statement" or a
  2970 ** "compiled SQL statement" or simply as a "statement".
  2971 **
  2972 ** The life of a statement object goes something like this:
  2973 **
  2974 ** <ol>
  2975 ** <li> Create the object using [sqlite3_prepare_v2()] or a related
  2976 **      function.
  2977 ** <li> Bind values to [host parameters] using the sqlite3_bind_*()
  2978 **      interfaces.
  2979 ** <li> Run the SQL by calling [sqlite3_step()] one or more times.
  2980 ** <li> Reset the statement using [sqlite3_reset()] then go back
  2981 **      to step 2.  Do this zero or more times.
  2982 ** <li> Destroy the object using [sqlite3_finalize()].
  2983 ** </ol>
  2984 **
  2985 ** Refer to documentation on individual methods above for additional
  2986 ** information.
  2987 */
  2988 typedef struct sqlite3_stmt sqlite3_stmt;
  2989 
  2990 /*
  2991 ** CAPI3REF: Run-time Limits
  2992 **
  2993 ** ^(This interface allows the size of various constructs to be limited
  2994 ** on a connection by connection basis.  The first parameter is the
  2995 ** [database connection] whose limit is to be set or queried.  The
  2996 ** second parameter is one of the [limit categories] that define a
  2997 ** class of constructs to be size limited.  The third parameter is the
  2998 ** new limit for that construct.)^
  2999 **
  3000 ** ^If the new limit is a negative number, the limit is unchanged.
  3001 ** ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a 
  3002 ** [limits | hard upper bound]
  3003 ** set at compile-time by a C preprocessor macro called
  3004 ** [limits | SQLITE_MAX_<i>NAME</i>].
  3005 ** (The "_LIMIT_" in the name is changed to "_MAX_".))^
  3006 ** ^Attempts to increase a limit above its hard upper bound are
  3007 ** silently truncated to the hard upper bound.
  3008 **
  3009 ** ^Regardless of whether or not the limit was changed, the 
  3010 ** [sqlite3_limit()] interface returns the prior value of the limit.
  3011 ** ^Hence, to find the current value of a limit without changing it,
  3012 ** simply invoke this interface with the third parameter set to -1.
  3013 **
  3014 ** Run-time limits are intended for use in applications that manage
  3015 ** both their own internal database and also databases that are controlled
  3016 ** by untrusted external sources.  An example application might be a
  3017 ** web browser that has its own databases for storing history and
  3018 ** separate databases controlled by JavaScript applications downloaded
  3019 ** off the Internet.  The internal databases can be given the
  3020 ** large, default limits.  Databases managed by external sources can
  3021 ** be given much smaller limits designed to prevent a denial of service
  3022 ** attack.  Developers might also want to use the [sqlite3_set_authorizer()]
  3023 ** interface to further control untrusted SQL.  The size of the database
  3024 ** created by an untrusted script can be contained using the
  3025 ** [max_page_count] [PRAGMA].
  3026 **
  3027 ** New run-time limit categories may be added in future releases.
  3028 */
  3029 SQLITE_API int sqlite3_limit(sqlite3*, int id, int newVal);
  3030 
  3031 /*
  3032 ** CAPI3REF: Run-Time Limit Categories
  3033 ** KEYWORDS: {limit category} {*limit categories}
  3034 **
  3035 ** These constants define various performance limits
  3036 ** that can be lowered at run-time using [sqlite3_limit()].
  3037 ** The synopsis of the meanings of the various limits is shown below.
  3038 ** Additional information is available at [limits | Limits in SQLite].
  3039 **
  3040 ** <dl>
  3041 ** [[SQLITE_LIMIT_LENGTH]] ^(<dt>SQLITE_LIMIT_LENGTH</dt>
  3042 ** <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^
  3043 **
  3044 ** [[SQLITE_LIMIT_SQL_LENGTH]] ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt>
  3045 ** <dd>The maximum length of an SQL statement, in bytes.</dd>)^
  3046 **
  3047 ** [[SQLITE_LIMIT_COLUMN]] ^(<dt>SQLITE_LIMIT_COLUMN</dt>
  3048 ** <dd>The maximum number of columns in a table definition or in the
  3049 ** result set of a [SELECT] or the maximum number of columns in an index
  3050 ** or in an ORDER BY or GROUP BY clause.</dd>)^
  3051 **
  3052 ** [[SQLITE_LIMIT_EXPR_DEPTH]] ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
  3053 ** <dd>The maximum depth of the parse tree on any expression.</dd>)^
  3054 **
  3055 ** [[SQLITE_LIMIT_COMPOUND_SELECT]] ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
  3056 ** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^
  3057 **
  3058 ** [[SQLITE_LIMIT_VDBE_OP]] ^(<dt>SQLITE_LIMIT_VDBE_OP</dt>
  3059 ** <dd>The maximum number of instructions in a virtual machine program
  3060 ** used to implement an SQL statement.  This limit is not currently
  3061 ** enforced, though that might be added in some future release of
  3062 ** SQLite.</dd>)^
  3063 **
  3064 ** [[SQLITE_LIMIT_FUNCTION_ARG]] ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
  3065 ** <dd>The maximum number of arguments on a function.</dd>)^
  3066 **
  3067 ** [[SQLITE_LIMIT_ATTACHED]] ^(<dt>SQLITE_LIMIT_ATTACHED</dt>
  3068 ** <dd>The maximum number of [ATTACH | attached databases].)^</dd>
  3069 **
  3070 ** [[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]]
  3071 ** ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
  3072 ** <dd>The maximum length of the pattern argument to the [LIKE] or
  3073 ** [GLOB] operators.</dd>)^
  3074 **
  3075 ** [[SQLITE_LIMIT_VARIABLE_NUMBER]]
  3076 ** ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
  3077 ** <dd>The maximum index number of any [parameter] in an SQL statement.)^
  3078 **
  3079 ** [[SQLITE_LIMIT_TRIGGER_DEPTH]] ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt>
  3080 ** <dd>The maximum depth of recursion for triggers.</dd>)^
  3081 ** </dl>
  3082 */
  3083 #define SQLITE_LIMIT_LENGTH                    0
  3084 #define SQLITE_LIMIT_SQL_LENGTH                1
  3085 #define SQLITE_LIMIT_COLUMN                    2
  3086 #define SQLITE_LIMIT_EXPR_DEPTH                3
  3087 #define SQLITE_LIMIT_COMPOUND_SELECT           4
  3088 #define SQLITE_LIMIT_VDBE_OP                   5
  3089 #define SQLITE_LIMIT_FUNCTION_ARG              6
  3090 #define SQLITE_LIMIT_ATTACHED                  7
  3091 #define SQLITE_LIMIT_LIKE_PATTERN_LENGTH       8
  3092 #define SQLITE_LIMIT_VARIABLE_NUMBER           9
  3093 #define SQLITE_LIMIT_TRIGGER_DEPTH            10
  3094 
  3095 /*
  3096 ** CAPI3REF: Compiling An SQL Statement
  3097 ** KEYWORDS: {SQL statement compiler}
  3098 **
  3099 ** To execute an SQL query, it must first be compiled into a byte-code
  3100 ** program using one of these routines.
  3101 **
  3102 ** The first argument, "db", is a [database connection] obtained from a
  3103 ** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or
  3104 ** [sqlite3_open16()].  The database connection must not have been closed.
  3105 **
  3106 ** The second argument, "zSql", is the statement to be compiled, encoded
  3107 ** as either UTF-8 or UTF-16.  The sqlite3_prepare() and sqlite3_prepare_v2()
  3108 ** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()
  3109 ** use UTF-16.
  3110 **
  3111 ** ^If the nByte argument is less than zero, then zSql is read up to the
  3112 ** first zero terminator. ^If nByte is non-negative, then it is the maximum
  3113 ** number of  bytes read from zSql.  ^When nByte is non-negative, the
  3114 ** zSql string ends at either the first '\000' or '\u0000' character or
  3115 ** the nByte-th byte, whichever comes first. If the caller knows
  3116 ** that the supplied string is nul-terminated, then there is a small
  3117 ** performance advantage to be gained by passing an nByte parameter that
  3118 ** is equal to the number of bytes in the input string <i>including</i>
  3119 ** the nul-terminator bytes as this saves SQLite from having to
  3120 ** make a copy of the input string.
  3121 **
  3122 ** ^If pzTail is not NULL then *pzTail is made to point to the first byte
  3123 ** past the end of the first SQL statement in zSql.  These routines only
  3124 ** compile the first statement in zSql, so *pzTail is left pointing to
  3125 ** what remains uncompiled.
  3126 **
  3127 ** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
  3128 ** executed using [sqlite3_step()].  ^If there is an error, *ppStmt is set
  3129 ** to NULL.  ^If the input text contains no SQL (if the input is an empty
  3130 ** string or a comment) then *ppStmt is set to NULL.
  3131 ** The calling procedure is responsible for deleting the compiled
  3132 ** SQL statement using [sqlite3_finalize()] after it has finished with it.
  3133 ** ppStmt may not be NULL.
  3134 **
  3135 ** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK];
  3136 ** otherwise an [error code] is returned.
  3137 **
  3138 ** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are
  3139 ** recommended for all new programs. The two older interfaces are retained
  3140 ** for backwards compatibility, but their use is discouraged.
  3141 ** ^In the "v2" interfaces, the prepared statement
  3142 ** that is returned (the [sqlite3_stmt] object) contains a copy of the
  3143 ** original SQL text. This causes the [sqlite3_step()] interface to
  3144 ** behave differently in three ways:
  3145 **
  3146 ** <ol>
  3147 ** <li>
  3148 ** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
  3149 ** always used to do, [sqlite3_step()] will automatically recompile the SQL
  3150 ** statement and try to run it again. As many as [SQLITE_MAX_SCHEMA_RETRY]
  3151 ** retries will occur before sqlite3_step() gives up and returns an error.
  3152 ** </li>
  3153 **
  3154 ** <li>
  3155 ** ^When an error occurs, [sqlite3_step()] will return one of the detailed
  3156 ** [error codes] or [extended error codes].  ^The legacy behavior was that
  3157 ** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
  3158 ** and the application would have to make a second call to [sqlite3_reset()]
  3159 ** in order to find the underlying cause of the problem. With the "v2" prepare
  3160 ** interfaces, the underlying reason for the error is returned immediately.
  3161 ** </li>
  3162 **
  3163 ** <li>
  3164 ** ^If the specific value bound to [parameter | host parameter] in the 
  3165 ** WHERE clause might influence the choice of query plan for a statement,
  3166 ** then the statement will be automatically recompiled, as if there had been 
  3167 ** a schema change, on the first  [sqlite3_step()] call following any change
  3168 ** to the [sqlite3_bind_text | bindings] of that [parameter]. 
  3169 ** ^The specific value of WHERE-clause [parameter] might influence the 
  3170 ** choice of query plan if the parameter is the left-hand side of a [LIKE]
  3171 ** or [GLOB] operator or if the parameter is compared to an indexed column
  3172 ** and the [SQLITE_ENABLE_STAT3] compile-time option is enabled.
  3173 ** </li>
  3174 ** </ol>
  3175 */
  3176 SQLITE_API int sqlite3_prepare(
  3177   sqlite3 *db,            /* Database handle */
  3178   const char *zSql,       /* SQL statement, UTF-8 encoded */
  3179   int nByte,              /* Maximum length of zSql in bytes. */
  3180   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3181   const char **pzTail     /* OUT: Pointer to unused portion of zSql */
  3182 );
  3183 SQLITE_API int sqlite3_prepare_v2(
  3184   sqlite3 *db,            /* Database handle */
  3185   const char *zSql,       /* SQL statement, UTF-8 encoded */
  3186   int nByte,              /* Maximum length of zSql in bytes. */
  3187   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3188   const char **pzTail     /* OUT: Pointer to unused portion of zSql */
  3189 );
  3190 SQLITE_API int sqlite3_prepare16(
  3191   sqlite3 *db,            /* Database handle */
  3192   const void *zSql,       /* SQL statement, UTF-16 encoded */
  3193   int nByte,              /* Maximum length of zSql in bytes. */
  3194   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3195   const void **pzTail     /* OUT: Pointer to unused portion of zSql */
  3196 );
  3197 SQLITE_API int sqlite3_prepare16_v2(
  3198   sqlite3 *db,            /* Database handle */
  3199   const void *zSql,       /* SQL statement, UTF-16 encoded */
  3200   int nByte,              /* Maximum length of zSql in bytes. */
  3201   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3202   const void **pzTail     /* OUT: Pointer to unused portion of zSql */
  3203 );
  3204 
  3205 /*
  3206 ** CAPI3REF: Retrieving Statement SQL
  3207 **
  3208 ** ^This interface can be used to retrieve a saved copy of the original
  3209 ** SQL text used to create a [prepared statement] if that statement was
  3210 ** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
  3211 */
  3212 SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt);
  3213 
  3214 /*
  3215 ** CAPI3REF: Determine If An SQL Statement Writes The Database
  3216 **
  3217 ** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if
  3218 ** and only if the [prepared statement] X makes no direct changes to
  3219 ** the content of the database file.
  3220 **
  3221 ** Note that [application-defined SQL functions] or
  3222 ** [virtual tables] might change the database indirectly as a side effect.  
  3223 ** ^(For example, if an application defines a function "eval()" that 
  3224 ** calls [sqlite3_exec()], then the following SQL statement would
  3225 ** change the database file through side-effects:
  3226 **
  3227 ** <blockquote><pre>
  3228 **    SELECT eval('DELETE FROM t1') FROM t2;
  3229 ** </pre></blockquote>
  3230 **
  3231 ** But because the [SELECT] statement does not change the database file
  3232 ** directly, sqlite3_stmt_readonly() would still return true.)^
  3233 **
  3234 ** ^Transaction control statements such as [BEGIN], [COMMIT], [ROLLBACK],
  3235 ** [SAVEPOINT], and [RELEASE] cause sqlite3_stmt_readonly() to return true,
  3236 ** since the statements themselves do not actually modify the database but
  3237 ** rather they control the timing of when other statements modify the 
  3238 ** database.  ^The [ATTACH] and [DETACH] statements also cause
  3239 ** sqlite3_stmt_readonly() to return true since, while those statements
  3240 ** change the configuration of a database connection, they do not make 
  3241 ** changes to the content of the database files on disk.
  3242 */
  3243 SQLITE_API int sqlite3_stmt_readonly(sqlite3_stmt *pStmt);
  3244 
  3245 /*
  3246 ** CAPI3REF: Determine If A Prepared Statement Has Been Reset
  3247 **
  3248 ** ^The sqlite3_stmt_busy(S) interface returns true (non-zero) if the
  3249 ** [prepared statement] S has been stepped at least once using 
  3250 ** [sqlite3_step(S)] but has not run to completion and/or has not 
  3251 ** been reset using [sqlite3_reset(S)].  ^The sqlite3_stmt_busy(S)
  3252 ** interface returns false if S is a NULL pointer.  If S is not a 
  3253 ** NULL pointer and is not a pointer to a valid [prepared statement]
  3254 ** object, then the behavior is undefined and probably undesirable.
  3255 **
  3256 ** This interface can be used in combination [sqlite3_next_stmt()]
  3257 ** to locate all prepared statements associated with a database 
  3258 ** connection that are in need of being reset.  This can be used,
  3259 ** for example, in diagnostic routines to search for prepared 
  3260 ** statements that are holding a transaction open.
  3261 */
  3262 SQLITE_API int sqlite3_stmt_busy(sqlite3_stmt*);
  3263 
  3264 /*
  3265 ** CAPI3REF: Dynamically Typed Value Object
  3266 ** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
  3267 **
  3268 ** SQLite uses the sqlite3_value object to represent all values
  3269 ** that can be stored in a database table. SQLite uses dynamic typing
  3270 ** for the values it stores.  ^Values stored in sqlite3_value objects
  3271 ** can be integers, floating point values, strings, BLOBs, or NULL.
  3272 **
  3273 ** An sqlite3_value object may be either "protected" or "unprotected".
  3274 ** Some interfaces require a protected sqlite3_value.  Other interfaces
  3275 ** will accept either a protected or an unprotected sqlite3_value.
  3276 ** Every interface that accepts sqlite3_value arguments specifies
  3277 ** whether or not it requires a protected sqlite3_value.
  3278 **
  3279 ** The terms "protected" and "unprotected" refer to whether or not
  3280 ** a mutex is held.  An internal mutex is held for a protected
  3281 ** sqlite3_value object but no mutex is held for an unprotected
  3282 ** sqlite3_value object.  If SQLite is compiled to be single-threaded
  3283 ** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
  3284 ** or if SQLite is run in one of reduced mutex modes 
  3285 ** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
  3286 ** then there is no distinction between protected and unprotected
  3287 ** sqlite3_value objects and they can be used interchangeably.  However,
  3288 ** for maximum code portability it is recommended that applications
  3289 ** still make the distinction between protected and unprotected
  3290 ** sqlite3_value objects even when not strictly required.
  3291 **
  3292 ** ^The sqlite3_value objects that are passed as parameters into the
  3293 ** implementation of [application-defined SQL functions] are protected.
  3294 ** ^The sqlite3_value object returned by
  3295 ** [sqlite3_column_value()] is unprotected.
  3296 ** Unprotected sqlite3_value objects may only be used with
  3297 ** [sqlite3_result_value()] and [sqlite3_bind_value()].
  3298 ** The [sqlite3_value_blob | sqlite3_value_type()] family of
  3299 ** interfaces require protected sqlite3_value objects.
  3300 */
  3301 typedef struct Mem sqlite3_value;
  3302 
  3303 /*
  3304 ** CAPI3REF: SQL Function Context Object
  3305 **
  3306 ** The context in which an SQL function executes is stored in an
  3307 ** sqlite3_context object.  ^A pointer to an sqlite3_context object
  3308 ** is always first parameter to [application-defined SQL functions].
  3309 ** The application-defined SQL function implementation will pass this
  3310 ** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
  3311 ** [sqlite3_aggregate_context()], [sqlite3_user_data()],
  3312 ** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
  3313 ** and/or [sqlite3_set_auxdata()].
  3314 */
  3315 typedef struct sqlite3_context sqlite3_context;
  3316 
  3317 /*
  3318 ** CAPI3REF: Binding Values To Prepared Statements
  3319 ** KEYWORDS: {host parameter} {host parameters} {host parameter name}
  3320 ** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
  3321 **
  3322 ** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants,
  3323 ** literals may be replaced by a [parameter] that matches one of following
  3324 ** templates:
  3325 **
  3326 ** <ul>
  3327 ** <li>  ?
  3328 ** <li>  ?NNN
  3329 ** <li>  :VVV
  3330 ** <li>  @VVV
  3331 ** <li>  $VVV
  3332 ** </ul>
  3333 **
  3334 ** In the templates above, NNN represents an integer literal,
  3335 ** and VVV represents an alphanumeric identifier.)^  ^The values of these
  3336 ** parameters (also called "host parameter names" or "SQL parameters")
  3337 ** can be set using the sqlite3_bind_*() routines defined here.
  3338 **
  3339 ** ^The first argument to the sqlite3_bind_*() routines is always
  3340 ** a pointer to the [sqlite3_stmt] object returned from
  3341 ** [sqlite3_prepare_v2()] or its variants.
  3342 **
  3343 ** ^The second argument is the index of the SQL parameter to be set.
  3344 ** ^The leftmost SQL parameter has an index of 1.  ^When the same named
  3345 ** SQL parameter is used more than once, second and subsequent
  3346 ** occurrences have the same index as the first occurrence.
  3347 ** ^The index for named parameters can be looked up using the
  3348 ** [sqlite3_bind_parameter_index()] API if desired.  ^The index
  3349 ** for "?NNN" parameters is the value of NNN.
  3350 ** ^The NNN value must be between 1 and the [sqlite3_limit()]
  3351 ** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
  3352 **
  3353 ** ^The third argument is the value to bind to the parameter.
  3354 ** ^If the third parameter to sqlite3_bind_text() or sqlite3_bind_text16()
  3355 ** or sqlite3_bind_blob() is a NULL pointer then the fourth parameter
  3356 ** is ignored and the end result is the same as sqlite3_bind_null().
  3357 **
  3358 ** ^(In those routines that have a fourth argument, its value is the
  3359 ** number of bytes in the parameter.  To be clear: the value is the
  3360 ** number of <u>bytes</u> in the value, not the number of characters.)^
  3361 ** ^If the fourth parameter to sqlite3_bind_text() or sqlite3_bind_text16()
  3362 ** is negative, then the length of the string is
  3363 ** the number of bytes up to the first zero terminator.
  3364 ** If the fourth parameter to sqlite3_bind_blob() is negative, then
  3365 ** the behavior is undefined.
  3366 ** If a non-negative fourth parameter is provided to sqlite3_bind_text()
  3367 ** or sqlite3_bind_text16() then that parameter must be the byte offset
  3368 ** where the NUL terminator would occur assuming the string were NUL
  3369 ** terminated.  If any NUL characters occur at byte offsets less than 
  3370 ** the value of the fourth parameter then the resulting string value will
  3371 ** contain embedded NULs.  The result of expressions involving strings
  3372 ** with embedded NULs is undefined.
  3373 **
  3374 ** ^The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
  3375 ** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
  3376 ** string after SQLite has finished with it.  ^The destructor is called
  3377 ** to dispose of the BLOB or string even if the call to sqlite3_bind_blob(),
  3378 ** sqlite3_bind_text(), or sqlite3_bind_text16() fails.  
  3379 ** ^If the fifth argument is
  3380 ** the special value [SQLITE_STATIC], then SQLite assumes that the
  3381 ** information is in static, unmanaged space and does not need to be freed.
  3382 ** ^If the fifth argument has the value [SQLITE_TRANSIENT], then
  3383 ** SQLite makes its own private copy of the data immediately, before
  3384 ** the sqlite3_bind_*() routine returns.
  3385 **
  3386 ** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
  3387 ** is filled with zeroes.  ^A zeroblob uses a fixed amount of memory
  3388 ** (just an integer to hold its size) while it is being processed.
  3389 ** Zeroblobs are intended to serve as placeholders for BLOBs whose
  3390 ** content is later written using
  3391 ** [sqlite3_blob_open | incremental BLOB I/O] routines.
  3392 ** ^A negative value for the zeroblob results in a zero-length BLOB.
  3393 **
  3394 ** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer
  3395 ** for the [prepared statement] or with a prepared statement for which
  3396 ** [sqlite3_step()] has been called more recently than [sqlite3_reset()],
  3397 ** then the call will return [SQLITE_MISUSE].  If any sqlite3_bind_()
  3398 ** routine is passed a [prepared statement] that has been finalized, the
  3399 ** result is undefined and probably harmful.
  3400 **
  3401 ** ^Bindings are not cleared by the [sqlite3_reset()] routine.
  3402 ** ^Unbound parameters are interpreted as NULL.
  3403 **
  3404 ** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an
  3405 ** [error code] if anything goes wrong.
  3406 ** ^[SQLITE_RANGE] is returned if the parameter
  3407 ** index is out of range.  ^[SQLITE_NOMEM] is returned if malloc() fails.
  3408 **
  3409 ** See also: [sqlite3_bind_parameter_count()],
  3410 ** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
  3411 */
  3412 SQLITE_API int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
  3413 SQLITE_API int sqlite3_bind_double(sqlite3_stmt*, int, double);
  3414 SQLITE_API int sqlite3_bind_int(sqlite3_stmt*, int, int);
  3415 SQLITE_API int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);
  3416 SQLITE_API int sqlite3_bind_null(sqlite3_stmt*, int);
  3417 SQLITE_API int sqlite3_bind_text(sqlite3_stmt*, int, const char*, int n, void(*)(void*));
  3418 SQLITE_API int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
  3419 SQLITE_API int sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*);
  3420 SQLITE_API int sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n);
  3421 
  3422 /*
  3423 ** CAPI3REF: Number Of SQL Parameters
  3424 **
  3425 ** ^This routine can be used to find the number of [SQL parameters]
  3426 ** in a [prepared statement].  SQL parameters are tokens of the
  3427 ** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
  3428 ** placeholders for values that are [sqlite3_bind_blob | bound]
  3429 ** to the parameters at a later time.
  3430 **
  3431 ** ^(This routine actually returns the index of the largest (rightmost)
  3432 ** parameter. For all forms except ?NNN, this will correspond to the
  3433 ** number of unique parameters.  If parameters of the ?NNN form are used,
  3434 ** there may be gaps in the list.)^
  3435 **
  3436 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3437 ** [sqlite3_bind_parameter_name()], and
  3438 ** [sqlite3_bind_parameter_index()].
  3439 */
  3440 SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt*);
  3441 
  3442 /*
  3443 ** CAPI3REF: Name Of A Host Parameter
  3444 **
  3445 ** ^The sqlite3_bind_parameter_name(P,N) interface returns
  3446 ** the name of the N-th [SQL parameter] in the [prepared statement] P.
  3447 ** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
  3448 ** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
  3449 ** respectively.
  3450 ** In other words, the initial ":" or "$" or "@" or "?"
  3451 ** is included as part of the name.)^
  3452 ** ^Parameters of the form "?" without a following integer have no name
  3453 ** and are referred to as "nameless" or "anonymous parameters".
  3454 **
  3455 ** ^The first host parameter has an index of 1, not 0.
  3456 **
  3457 ** ^If the value N is out of range or if the N-th parameter is
  3458 ** nameless, then NULL is returned.  ^The returned string is
  3459 ** always in UTF-8 encoding even if the named parameter was
  3460 ** originally specified as UTF-16 in [sqlite3_prepare16()] or
  3461 ** [sqlite3_prepare16_v2()].
  3462 **
  3463 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3464 ** [sqlite3_bind_parameter_count()], and
  3465 ** [sqlite3_bind_parameter_index()].
  3466 */
  3467 SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt*, int);
  3468 
  3469 /*
  3470 ** CAPI3REF: Index Of A Parameter With A Given Name
  3471 **
  3472 ** ^Return the index of an SQL parameter given its name.  ^The
  3473 ** index value returned is suitable for use as the second
  3474 ** parameter to [sqlite3_bind_blob|sqlite3_bind()].  ^A zero
  3475 ** is returned if no matching parameter is found.  ^The parameter
  3476 ** name must be given in UTF-8 even if the original statement
  3477 ** was prepared from UTF-16 text using [sqlite3_prepare16_v2()].
  3478 **
  3479 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3480 ** [sqlite3_bind_parameter_count()], and
  3481 ** [sqlite3_bind_parameter_index()].
  3482 */
  3483 SQLITE_API int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);
  3484 
  3485 /*
  3486 ** CAPI3REF: Reset All Bindings On A Prepared Statement
  3487 **
  3488 ** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset
  3489 ** the [sqlite3_bind_blob | bindings] on a [prepared statement].
  3490 ** ^Use this routine to reset all host parameters to NULL.
  3491 */
  3492 SQLITE_API int sqlite3_clear_bindings(sqlite3_stmt*);
  3493 
  3494 /*
  3495 ** CAPI3REF: Number Of Columns In A Result Set
  3496 **
  3497 ** ^Return the number of columns in the result set returned by the
  3498 ** [prepared statement]. ^This routine returns 0 if pStmt is an SQL
  3499 ** statement that does not return data (for example an [UPDATE]).
  3500 **
  3501 ** See also: [sqlite3_data_count()]
  3502 */
  3503 SQLITE_API int sqlite3_column_count(sqlite3_stmt *pStmt);
  3504 
  3505 /*
  3506 ** CAPI3REF: Column Names In A Result Set
  3507 **
  3508 ** ^These routines return the name assigned to a particular column
  3509 ** in the result set of a [SELECT] statement.  ^The sqlite3_column_name()
  3510 ** interface returns a pointer to a zero-terminated UTF-8 string
  3511 ** and sqlite3_column_name16() returns a pointer to a zero-terminated
  3512 ** UTF-16 string.  ^The first parameter is the [prepared statement]
  3513 ** that implements the [SELECT] statement. ^The second parameter is the
  3514 ** column number.  ^The leftmost column is number 0.
  3515 **
  3516 ** ^The returned string pointer is valid until either the [prepared statement]
  3517 ** is destroyed by [sqlite3_finalize()] or until the statement is automatically
  3518 ** reprepared by the first call to [sqlite3_step()] for a particular run
  3519 ** or until the next call to
  3520 ** sqlite3_column_name() or sqlite3_column_name16() on the same column.
  3521 **
  3522 ** ^If sqlite3_malloc() fails during the processing of either routine
  3523 ** (for example during a conversion from UTF-8 to UTF-16) then a
  3524 ** NULL pointer is returned.
  3525 **
  3526 ** ^The name of a result column is the value of the "AS" clause for
  3527 ** that column, if there is an AS clause.  If there is no AS clause
  3528 ** then the name of the column is unspecified and may change from
  3529 ** one release of SQLite to the next.
  3530 */
  3531 SQLITE_API const char *sqlite3_column_name(sqlite3_stmt*, int N);
  3532 SQLITE_API const void *sqlite3_column_name16(sqlite3_stmt*, int N);
  3533 
  3534 /*
  3535 ** CAPI3REF: Source Of Data In A Query Result
  3536 **
  3537 ** ^These routines provide a means to determine the database, table, and
  3538 ** table column that is the origin of a particular result column in
  3539 ** [SELECT] statement.
  3540 ** ^The name of the database or table or column can be returned as
  3541 ** either a UTF-8 or UTF-16 string.  ^The _database_ routines return
  3542 ** the database name, the _table_ routines return the table name, and
  3543 ** the origin_ routines return the column name.
  3544 ** ^The returned string is valid until the [prepared statement] is destroyed
  3545 ** using [sqlite3_finalize()] or until the statement is automatically
  3546 ** reprepared by the first call to [sqlite3_step()] for a particular run
  3547 ** or until the same information is requested
  3548 ** again in a different encoding.
  3549 **
  3550 ** ^The names returned are the original un-aliased names of the
  3551 ** database, table, and column.
  3552 **
  3553 ** ^The first argument to these interfaces is a [prepared statement].
  3554 ** ^These functions return information about the Nth result column returned by
  3555 ** the statement, where N is the second function argument.
  3556 ** ^The left-most column is column 0 for these routines.
  3557 **
  3558 ** ^If the Nth column returned by the statement is an expression or
  3559 ** subquery and is not a column value, then all of these functions return
  3560 ** NULL.  ^These routine might also return NULL if a memory allocation error
  3561 ** occurs.  ^Otherwise, they return the name of the attached database, table,
  3562 ** or column that query result column was extracted from.
  3563 **
  3564 ** ^As with all other SQLite APIs, those whose names end with "16" return
  3565 ** UTF-16 encoded strings and the other functions return UTF-8.
  3566 **
  3567 ** ^These APIs are only available if the library was compiled with the
  3568 ** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol.
  3569 **
  3570 ** If two or more threads call one or more of these routines against the same
  3571 ** prepared statement and column at the same time then the results are
  3572 ** undefined.
  3573 **
  3574 ** If two or more threads call one or more
  3575 ** [sqlite3_column_database_name | column metadata interfaces]
  3576 ** for the same [prepared statement] and result column
  3577 ** at the same time then the results are undefined.
  3578 */
  3579 SQLITE_API const char *sqlite3_column_database_name(sqlite3_stmt*,int);
  3580 SQLITE_API const void *sqlite3_column_database_name16(sqlite3_stmt*,int);
  3581 SQLITE_API const char *sqlite3_column_table_name(sqlite3_stmt*,int);
  3582 SQLITE_API const void *sqlite3_column_table_name16(sqlite3_stmt*,int);
  3583 SQLITE_API const char *sqlite3_column_origin_name(sqlite3_stmt*,int);
  3584 SQLITE_API const void *sqlite3_column_origin_name16(sqlite3_stmt*,int);
  3585 
  3586 /*
  3587 ** CAPI3REF: Declared Datatype Of A Query Result
  3588 **
  3589 ** ^(The first parameter is a [prepared statement].
  3590 ** If this statement is a [SELECT] statement and the Nth column of the
  3591 ** returned result set of that [SELECT] is a table column (not an
  3592 ** expression or subquery) then the declared type of the table
  3593 ** column is returned.)^  ^If the Nth column of the result set is an
  3594 ** expression or subquery, then a NULL pointer is returned.
  3595 ** ^The returned string is always UTF-8 encoded.
  3596 **
  3597 ** ^(For example, given the database schema:
  3598 **
  3599 ** CREATE TABLE t1(c1 VARIANT);
  3600 **
  3601 ** and the following statement to be compiled:
  3602 **
  3603 ** SELECT c1 + 1, c1 FROM t1;
  3604 **
  3605 ** this routine would return the string "VARIANT" for the second result
  3606 ** column (i==1), and a NULL pointer for the first result column (i==0).)^
  3607 **
  3608 ** ^SQLite uses dynamic run-time typing.  ^So just because a column
  3609 ** is declared to contain a particular type does not mean that the
  3610 ** data stored in that column is of the declared type.  SQLite is
  3611 ** strongly typed, but the typing is dynamic not static.  ^Type
  3612 ** is associated with individual values, not with the containers
  3613 ** used to hold those values.
  3614 */
  3615 SQLITE_API const char *sqlite3_column_decltype(sqlite3_stmt*,int);
  3616 SQLITE_API const void *sqlite3_column_decltype16(sqlite3_stmt*,int);
  3617 
  3618 /*
  3619 ** CAPI3REF: Evaluate An SQL Statement
  3620 **
  3621 ** After a [prepared statement] has been prepared using either
  3622 ** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy
  3623 ** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
  3624 ** must be called one or more times to evaluate the statement.
  3625 **
  3626 ** The details of the behavior of the sqlite3_step() interface depend
  3627 ** on whether the statement was prepared using the newer "v2" interface
  3628 ** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy
  3629 ** interface [sqlite3_prepare()] and [sqlite3_prepare16()].  The use of the
  3630 ** new "v2" interface is recommended for new applications but the legacy
  3631 ** interface will continue to be supported.
  3632 **
  3633 ** ^In the legacy interface, the return value will be either [SQLITE_BUSY],
  3634 ** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
  3635 ** ^With the "v2" interface, any of the other [result codes] or
  3636 ** [extended result codes] might be returned as well.
  3637 **
  3638 ** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
  3639 ** database locks it needs to do its job.  ^If the statement is a [COMMIT]
  3640 ** or occurs outside of an explicit transaction, then you can retry the
  3641 ** statement.  If the statement is not a [COMMIT] and occurs within an
  3642 ** explicit transaction then you should rollback the transaction before
  3643 ** continuing.
  3644 **
  3645 ** ^[SQLITE_DONE] means that the statement has finished executing
  3646 ** successfully.  sqlite3_step() should not be called again on this virtual
  3647 ** machine without first calling [sqlite3_reset()] to reset the virtual
  3648 ** machine back to its initial state.
  3649 **
  3650 ** ^If the SQL statement being executed returns any data, then [SQLITE_ROW]
  3651 ** is returned each time a new row of data is ready for processing by the
  3652 ** caller. The values may be accessed using the [column access functions].
  3653 ** sqlite3_step() is called again to retrieve the next row of data.
  3654 **
  3655 ** ^[SQLITE_ERROR] means that a run-time error (such as a constraint
  3656 ** violation) has occurred.  sqlite3_step() should not be called again on
  3657 ** the VM. More information may be found by calling [sqlite3_errmsg()].
  3658 ** ^With the legacy interface, a more specific error code (for example,
  3659 ** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
  3660 ** can be obtained by calling [sqlite3_reset()] on the
  3661 ** [prepared statement].  ^In the "v2" interface,
  3662 ** the more specific error code is returned directly by sqlite3_step().
  3663 **
  3664 ** [SQLITE_MISUSE] means that the this routine was called inappropriately.
  3665 ** Perhaps it was called on a [prepared statement] that has
  3666 ** already been [sqlite3_finalize | finalized] or on one that had
  3667 ** previously returned [SQLITE_ERROR] or [SQLITE_DONE].  Or it could
  3668 ** be the case that the same database connection is being used by two or
  3669 ** more threads at the same moment in time.
  3670 **
  3671 ** For all versions of SQLite up to and including 3.6.23.1, a call to
  3672 ** [sqlite3_reset()] was required after sqlite3_step() returned anything
  3673 ** other than [SQLITE_ROW] before any subsequent invocation of
  3674 ** sqlite3_step().  Failure to reset the prepared statement using 
  3675 ** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
  3676 ** sqlite3_step().  But after version 3.6.23.1, sqlite3_step() began
  3677 ** calling [sqlite3_reset()] automatically in this circumstance rather
  3678 ** than returning [SQLITE_MISUSE].  This is not considered a compatibility
  3679 ** break because any application that ever receives an SQLITE_MISUSE error
  3680 ** is broken by definition.  The [SQLITE_OMIT_AUTORESET] compile-time option
  3681 ** can be used to restore the legacy behavior.
  3682 **
  3683 ** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
  3684 ** API always returns a generic error code, [SQLITE_ERROR], following any
  3685 ** error other than [SQLITE_BUSY] and [SQLITE_MISUSE].  You must call
  3686 ** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
  3687 ** specific [error codes] that better describes the error.
  3688 ** We admit that this is a goofy design.  The problem has been fixed
  3689 ** with the "v2" interface.  If you prepare all of your SQL statements
  3690 ** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead
  3691 ** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
  3692 ** then the more specific [error codes] are returned directly
  3693 ** by sqlite3_step().  The use of the "v2" interface is recommended.
  3694 */
  3695 SQLITE_API int sqlite3_step(sqlite3_stmt*);
  3696 
  3697 /*
  3698 ** CAPI3REF: Number of columns in a result set
  3699 **
  3700 ** ^The sqlite3_data_count(P) interface returns the number of columns in the
  3701 ** current row of the result set of [prepared statement] P.
  3702 ** ^If prepared statement P does not have results ready to return
  3703 ** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
  3704 ** interfaces) then sqlite3_data_count(P) returns 0.
  3705 ** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
  3706 ** ^The sqlite3_data_count(P) routine returns 0 if the previous call to
  3707 ** [sqlite3_step](P) returned [SQLITE_DONE].  ^The sqlite3_data_count(P)
  3708 ** will return non-zero if previous call to [sqlite3_step](P) returned
  3709 ** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]
  3710 ** where it always returns zero since each step of that multi-step
  3711 ** pragma returns 0 columns of data.
  3712 **
  3713 ** See also: [sqlite3_column_count()]
  3714 */
  3715 SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt);
  3716 
  3717 /*
  3718 ** CAPI3REF: Fundamental Datatypes
  3719 ** KEYWORDS: SQLITE_TEXT
  3720 **
  3721 ** ^(Every value in SQLite has one of five fundamental datatypes:
  3722 **
  3723 ** <ul>
  3724 ** <li> 64-bit signed integer
  3725 ** <li> 64-bit IEEE floating point number
  3726 ** <li> string
  3727 ** <li> BLOB
  3728 ** <li> NULL
  3729 ** </ul>)^
  3730 **
  3731 ** These constants are codes for each of those types.
  3732 **
  3733 ** Note that the SQLITE_TEXT constant was also used in SQLite version 2
  3734 ** for a completely different meaning.  Software that links against both
  3735 ** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
  3736 ** SQLITE_TEXT.
  3737 */
  3738 #define SQLITE_INTEGER  1
  3739 #define SQLITE_FLOAT    2
  3740 #define SQLITE_BLOB     4
  3741 #define SQLITE_NULL     5
  3742 #ifdef SQLITE_TEXT
  3743 # undef SQLITE_TEXT
  3744 #else
  3745 # define SQLITE_TEXT     3
  3746 #endif
  3747 #define SQLITE3_TEXT     3
  3748 
  3749 /*
  3750 ** CAPI3REF: Result Values From A Query
  3751 ** KEYWORDS: {column access functions}
  3752 **
  3753 ** These routines form the "result set" interface.
  3754 **
  3755 ** ^These routines return information about a single column of the current
  3756 ** result row of a query.  ^In every case the first argument is a pointer
  3757 ** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
  3758 ** that was returned from [sqlite3_prepare_v2()] or one of its variants)
  3759 ** and the second argument is the index of the column for which information
  3760 ** should be returned. ^The leftmost column of the result set has the index 0.
  3761 ** ^The number of columns in the result can be determined using
  3762 ** [sqlite3_column_count()].
  3763 **
  3764 ** If the SQL statement does not currently point to a valid row, or if the
  3765 ** column index is out of range, the result is undefined.
  3766 ** These routines may only be called when the most recent call to
  3767 ** [sqlite3_step()] has returned [SQLITE_ROW] and neither
  3768 ** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
  3769 ** If any of these routines are called after [sqlite3_reset()] or
  3770 ** [sqlite3_finalize()] or after [sqlite3_step()] has returned
  3771 ** something other than [SQLITE_ROW], the results are undefined.
  3772 ** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
  3773 ** are called from a different thread while any of these routines
  3774 ** are pending, then the results are undefined.
  3775 **
  3776 ** ^The sqlite3_column_type() routine returns the
  3777 ** [SQLITE_INTEGER | datatype code] for the initial data type
  3778 ** of the result column.  ^The returned value is one of [SQLITE_INTEGER],
  3779 ** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL].  The value
  3780 ** returned by sqlite3_column_type() is only meaningful if no type
  3781 ** conversions have occurred as described below.  After a type conversion,
  3782 ** the value returned by sqlite3_column_type() is undefined.  Future
  3783 ** versions of SQLite may change the behavior of sqlite3_column_type()
  3784 ** following a type conversion.
  3785 **
  3786 ** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
  3787 ** routine returns the number of bytes in that BLOB or string.
  3788 ** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts
  3789 ** the string to UTF-8 and then returns the number of bytes.
  3790 ** ^If the result is a numeric value then sqlite3_column_bytes() uses
  3791 ** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
  3792 ** the number of bytes in that string.
  3793 ** ^If the result is NULL, then sqlite3_column_bytes() returns zero.
  3794 **
  3795 ** ^If the result is a BLOB or UTF-16 string then the sqlite3_column_bytes16()
  3796 ** routine returns the number of bytes in that BLOB or string.
  3797 ** ^If the result is a UTF-8 string, then sqlite3_column_bytes16() converts
  3798 ** the string to UTF-16 and then returns the number of bytes.
  3799 ** ^If the result is a numeric value then sqlite3_column_bytes16() uses
  3800 ** [sqlite3_snprintf()] to convert that value to a UTF-16 string and returns
  3801 ** the number of bytes in that string.
  3802 ** ^If the result is NULL, then sqlite3_column_bytes16() returns zero.
  3803 **
  3804 ** ^The values returned by [sqlite3_column_bytes()] and 
  3805 ** [sqlite3_column_bytes16()] do not include the zero terminators at the end
  3806 ** of the string.  ^For clarity: the values returned by
  3807 ** [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] are the number of
  3808 ** bytes in the string, not the number of characters.
  3809 **
  3810 ** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
  3811 ** even empty strings, are always zero-terminated.  ^The return
  3812 ** value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer.
  3813 **
  3814 ** ^The object returned by [sqlite3_column_value()] is an
  3815 ** [unprotected sqlite3_value] object.  An unprotected sqlite3_value object
  3816 ** may only be used with [sqlite3_bind_value()] and [sqlite3_result_value()].
  3817 ** If the [unprotected sqlite3_value] object returned by
  3818 ** [sqlite3_column_value()] is used in any other way, including calls
  3819 ** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
  3820 ** or [sqlite3_value_bytes()], then the behavior is undefined.
  3821 **
  3822 ** These routines attempt to convert the value where appropriate.  ^For
  3823 ** example, if the internal representation is FLOAT and a text result
  3824 ** is requested, [sqlite3_snprintf()] is used internally to perform the
  3825 ** conversion automatically.  ^(The following table details the conversions
  3826 ** that are applied:
  3827 **
  3828 ** <blockquote>
  3829 ** <table border="1">
  3830 ** <tr><th> Internal<br>Type <th> Requested<br>Type <th>  Conversion
  3831 **
  3832 ** <tr><td>  NULL    <td> INTEGER   <td> Result is 0
  3833 ** <tr><td>  NULL    <td>  FLOAT    <td> Result is 0.0
  3834 ** <tr><td>  NULL    <td>   TEXT    <td> Result is a NULL pointer
  3835 ** <tr><td>  NULL    <td>   BLOB    <td> Result is a NULL pointer
  3836 ** <tr><td> INTEGER  <td>  FLOAT    <td> Convert from integer to float
  3837 ** <tr><td> INTEGER  <td>   TEXT    <td> ASCII rendering of the integer
  3838 ** <tr><td> INTEGER  <td>   BLOB    <td> Same as INTEGER->TEXT
  3839 ** <tr><td>  FLOAT   <td> INTEGER   <td> [CAST] to INTEGER
  3840 ** <tr><td>  FLOAT   <td>   TEXT    <td> ASCII rendering of the float
  3841 ** <tr><td>  FLOAT   <td>   BLOB    <td> [CAST] to BLOB
  3842 ** <tr><td>  TEXT    <td> INTEGER   <td> [CAST] to INTEGER
  3843 ** <tr><td>  TEXT    <td>  FLOAT    <td> [CAST] to REAL
  3844 ** <tr><td>  TEXT    <td>   BLOB    <td> No change
  3845 ** <tr><td>  BLOB    <td> INTEGER   <td> [CAST] to INTEGER
  3846 ** <tr><td>  BLOB    <td>  FLOAT    <td> [CAST] to REAL
  3847 ** <tr><td>  BLOB    <td>   TEXT    <td> Add a zero terminator if needed
  3848 ** </table>
  3849 ** </blockquote>)^
  3850 **
  3851 ** The table above makes reference to standard C library functions atoi()
  3852 ** and atof().  SQLite does not really use these functions.  It has its
  3853 ** own equivalent internal routines.  The atoi() and atof() names are
  3854 ** used in the table for brevity and because they are familiar to most
  3855 ** C programmers.
  3856 **
  3857 ** Note that when type conversions occur, pointers returned by prior
  3858 ** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
  3859 ** sqlite3_column_text16() may be invalidated.
  3860 ** Type conversions and pointer invalidations might occur
  3861 ** in the following cases:
  3862 **
  3863 ** <ul>
  3864 ** <li> The initial content is a BLOB and sqlite3_column_text() or
  3865 **      sqlite3_column_text16() is called.  A zero-terminator might
  3866 **      need to be added to the string.</li>
  3867 ** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
  3868 **      sqlite3_column_text16() is called.  The content must be converted
  3869 **      to UTF-16.</li>
  3870 ** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
  3871 **      sqlite3_column_text() is called.  The content must be converted
  3872 **      to UTF-8.</li>
  3873 ** </ul>
  3874 **
  3875 ** ^Conversions between UTF-16be and UTF-16le are always done in place and do
  3876 ** not invalidate a prior pointer, though of course the content of the buffer
  3877 ** that the prior pointer references will have been modified.  Other kinds
  3878 ** of conversion are done in place when it is possible, but sometimes they
  3879 ** are not possible and in those cases prior pointers are invalidated.
  3880 **
  3881 ** The safest and easiest to remember policy is to invoke these routines
  3882 ** in one of the following ways:
  3883 **
  3884 ** <ul>
  3885 **  <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
  3886 **  <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
  3887 **  <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
  3888 ** </ul>
  3889 **
  3890 ** In other words, you should call sqlite3_column_text(),
  3891 ** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
  3892 ** into the desired format, then invoke sqlite3_column_bytes() or
  3893 ** sqlite3_column_bytes16() to find the size of the result.  Do not mix calls
  3894 ** to sqlite3_column_text() or sqlite3_column_blob() with calls to
  3895 ** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
  3896 ** with calls to sqlite3_column_bytes().
  3897 **
  3898 ** ^The pointers returned are valid until a type conversion occurs as
  3899 ** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
  3900 ** [sqlite3_finalize()] is called.  ^The memory space used to hold strings
  3901 ** and BLOBs is freed automatically.  Do <b>not</b> pass the pointers returned
  3902 ** from [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
  3903 ** [sqlite3_free()].
  3904 **
  3905 ** ^(If a memory allocation error occurs during the evaluation of any
  3906 ** of these routines, a default value is returned.  The default value
  3907 ** is either the integer 0, the floating point number 0.0, or a NULL
  3908 ** pointer.  Subsequent calls to [sqlite3_errcode()] will return
  3909 ** [SQLITE_NOMEM].)^
  3910 */
  3911 SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
  3912 SQLITE_API int sqlite3_column_bytes(sqlite3_stmt*, int iCol);
  3913 SQLITE_API int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
  3914 SQLITE_API double sqlite3_column_double(sqlite3_stmt*, int iCol);
  3915 SQLITE_API int sqlite3_column_int(sqlite3_stmt*, int iCol);
  3916 SQLITE_API sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
  3917 SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
  3918 SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
  3919 SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
  3920 SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);
  3921 
  3922 /*
  3923 ** CAPI3REF: Destroy A Prepared Statement Object
  3924 **
  3925 ** ^The sqlite3_finalize() function is called to delete a [prepared statement].
  3926 ** ^If the most recent evaluation of the statement encountered no errors
  3927 ** or if the statement is never been evaluated, then sqlite3_finalize() returns
  3928 ** SQLITE_OK.  ^If the most recent evaluation of statement S failed, then
  3929 ** sqlite3_finalize(S) returns the appropriate [error code] or
  3930 ** [extended error code].
  3931 **
  3932 ** ^The sqlite3_finalize(S) routine can be called at any point during
  3933 ** the life cycle of [prepared statement] S:
  3934 ** before statement S is ever evaluated, after
  3935 ** one or more calls to [sqlite3_reset()], or after any call
  3936 ** to [sqlite3_step()] regardless of whether or not the statement has
  3937 ** completed execution.
  3938 **
  3939 ** ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op.
  3940 **
  3941 ** The application must finalize every [prepared statement] in order to avoid
  3942 ** resource leaks.  It is a grievous error for the application to try to use
  3943 ** a prepared statement after it has been finalized.  Any use of a prepared
  3944 ** statement after it has been finalized can result in undefined and
  3945 ** undesirable behavior such as segfaults and heap corruption.
  3946 */
  3947 SQLITE_API int sqlite3_finalize(sqlite3_stmt *pStmt);
  3948 
  3949 /*
  3950 ** CAPI3REF: Reset A Prepared Statement Object
  3951 **
  3952 ** The sqlite3_reset() function is called to reset a [prepared statement]
  3953 ** object back to its initial state, ready to be re-executed.
  3954 ** ^Any SQL statement variables that had values bound to them using
  3955 ** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
  3956 ** Use [sqlite3_clear_bindings()] to reset the bindings.
  3957 **
  3958 ** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S
  3959 ** back to the beginning of its program.
  3960 **
  3961 ** ^If the most recent call to [sqlite3_step(S)] for the
  3962 ** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
  3963 ** or if [sqlite3_step(S)] has never before been called on S,
  3964 ** then [sqlite3_reset(S)] returns [SQLITE_OK].
  3965 **
  3966 ** ^If the most recent call to [sqlite3_step(S)] for the
  3967 ** [prepared statement] S indicated an error, then
  3968 ** [sqlite3_reset(S)] returns an appropriate [error code].
  3969 **
  3970 ** ^The [sqlite3_reset(S)] interface does not change the values
  3971 ** of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
  3972 */
  3973 SQLITE_API int sqlite3_reset(sqlite3_stmt *pStmt);
  3974 
  3975 /*
  3976 ** CAPI3REF: Create Or Redefine SQL Functions
  3977 ** KEYWORDS: {function creation routines}
  3978 ** KEYWORDS: {application-defined SQL function}
  3979 ** KEYWORDS: {application-defined SQL functions}
  3980 **
  3981 ** ^These functions (collectively known as "function creation routines")
  3982 ** are used to add SQL functions or aggregates or to redefine the behavior
  3983 ** of existing SQL functions or aggregates.  The only differences between
  3984 ** these routines are the text encoding expected for
  3985 ** the second parameter (the name of the function being created)
  3986 ** and the presence or absence of a destructor callback for
  3987 ** the application data pointer.
  3988 **
  3989 ** ^The first parameter is the [database connection] to which the SQL
  3990 ** function is to be added.  ^If an application uses more than one database
  3991 ** connection then application-defined SQL functions must be added
  3992 ** to each database connection separately.
  3993 **
  3994 ** ^The second parameter is the name of the SQL function to be created or
  3995 ** redefined.  ^The length of the name is limited to 255 bytes in a UTF-8
  3996 ** representation, exclusive of the zero-terminator.  ^Note that the name
  3997 ** length limit is in UTF-8 bytes, not characters nor UTF-16 bytes.  
  3998 ** ^Any attempt to create a function with a longer name
  3999 ** will result in [SQLITE_MISUSE] being returned.
  4000 **
  4001 ** ^The third parameter (nArg)
  4002 ** is the number of arguments that the SQL function or
  4003 ** aggregate takes. ^If this parameter is -1, then the SQL function or
  4004 ** aggregate may take any number of arguments between 0 and the limit
  4005 ** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]).  If the third
  4006 ** parameter is less than -1 or greater than 127 then the behavior is
  4007 ** undefined.
  4008 **
  4009 ** ^The fourth parameter, eTextRep, specifies what
  4010 ** [SQLITE_UTF8 | text encoding] this SQL function prefers for
  4011 ** its parameters.  The application should set this parameter to
  4012 ** [SQLITE_UTF16LE] if the function implementation invokes 
  4013 ** [sqlite3_value_text16le()] on an input, or [SQLITE_UTF16BE] if the
  4014 ** implementation invokes [sqlite3_value_text16be()] on an input, or
  4015 ** [SQLITE_UTF16] if [sqlite3_value_text16()] is used, or [SQLITE_UTF8]
  4016 ** otherwise.  ^The same SQL function may be registered multiple times using
  4017 ** different preferred text encodings, with different implementations for
  4018 ** each encoding.
  4019 ** ^When multiple implementations of the same function are available, SQLite
  4020 ** will pick the one that involves the least amount of data conversion.
  4021 **
  4022 ** ^The fourth parameter may optionally be ORed with [SQLITE_DETERMINISTIC]
  4023 ** to signal that the function will always return the same result given
  4024 ** the same inputs within a single SQL statement.  Most SQL functions are
  4025 ** deterministic.  The built-in [random()] SQL function is an example of a
  4026 ** function that is not deterministic.  The SQLite query planner is able to
  4027 ** perform additional optimizations on deterministic functions, so use
  4028 ** of the [SQLITE_DETERMINISTIC] flag is recommended where possible.
  4029 **
  4030 ** ^(The fifth parameter is an arbitrary pointer.  The implementation of the
  4031 ** function can gain access to this pointer using [sqlite3_user_data()].)^
  4032 **
  4033 ** ^The sixth, seventh and eighth parameters, xFunc, xStep and xFinal, are
  4034 ** pointers to C-language functions that implement the SQL function or
  4035 ** aggregate. ^A scalar SQL function requires an implementation of the xFunc
  4036 ** callback only; NULL pointers must be passed as the xStep and xFinal
  4037 ** parameters. ^An aggregate SQL function requires an implementation of xStep
  4038 ** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
  4039 ** SQL function or aggregate, pass NULL pointers for all three function
  4040 ** callbacks.
  4041 **
  4042 ** ^(If the ninth parameter to sqlite3_create_function_v2() is not NULL,
  4043 ** then it is destructor for the application data pointer. 
  4044 ** The destructor is invoked when the function is deleted, either by being
  4045 ** overloaded or when the database connection closes.)^
  4046 ** ^The destructor is also invoked if the call to
  4047 ** sqlite3_create_function_v2() fails.
  4048 ** ^When the destructor callback of the tenth parameter is invoked, it
  4049 ** is passed a single argument which is a copy of the application data 
  4050 ** pointer which was the fifth parameter to sqlite3_create_function_v2().
  4051 **
  4052 ** ^It is permitted to register multiple implementations of the same
  4053 ** functions with the same name but with either differing numbers of
  4054 ** arguments or differing preferred text encodings.  ^SQLite will use
  4055 ** the implementation that most closely matches the way in which the
  4056 ** SQL function is used.  ^A function implementation with a non-negative
  4057 ** nArg parameter is a better match than a function implementation with
  4058 ** a negative nArg.  ^A function where the preferred text encoding
  4059 ** matches the database encoding is a better
  4060 ** match than a function where the encoding is different.  
  4061 ** ^A function where the encoding difference is between UTF16le and UTF16be
  4062 ** is a closer match than a function where the encoding difference is
  4063 ** between UTF8 and UTF16.
  4064 **
  4065 ** ^Built-in functions may be overloaded by new application-defined functions.
  4066 **
  4067 ** ^An application-defined function is permitted to call other
  4068 ** SQLite interfaces.  However, such calls must not
  4069 ** close the database connection nor finalize or reset the prepared
  4070 ** statement in which the function is running.
  4071 */
  4072 SQLITE_API int sqlite3_create_function(
  4073   sqlite3 *db,
  4074   const char *zFunctionName,
  4075   int nArg,
  4076   int eTextRep,
  4077   void *pApp,
  4078   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4079   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4080   void (*xFinal)(sqlite3_context*)
  4081 );
  4082 SQLITE_API int sqlite3_create_function16(
  4083   sqlite3 *db,
  4084   const void *zFunctionName,
  4085   int nArg,
  4086   int eTextRep,
  4087   void *pApp,
  4088   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4089   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4090   void (*xFinal)(sqlite3_context*)
  4091 );
  4092 SQLITE_API int sqlite3_create_function_v2(
  4093   sqlite3 *db,
  4094   const char *zFunctionName,
  4095   int nArg,
  4096   int eTextRep,
  4097   void *pApp,
  4098   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4099   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4100   void (*xFinal)(sqlite3_context*),
  4101   void(*xDestroy)(void*)
  4102 );
  4103 
  4104 /*
  4105 ** CAPI3REF: Text Encodings
  4106 **
  4107 ** These constant define integer codes that represent the various
  4108 ** text encodings supported by SQLite.
  4109 */
  4110 #define SQLITE_UTF8           1
  4111 #define SQLITE_UTF16LE        2
  4112 #define SQLITE_UTF16BE        3
  4113 #define SQLITE_UTF16          4    /* Use native byte order */
  4114 #define SQLITE_ANY            5    /* Deprecated */
  4115 #define SQLITE_UTF16_ALIGNED  8    /* sqlite3_create_collation only */
  4116 
  4117 /*
  4118 ** CAPI3REF: Function Flags
  4119 **
  4120 ** These constants may be ORed together with the 
  4121 ** [SQLITE_UTF8 | preferred text encoding] as the fourth argument
  4122 ** to [sqlite3_create_function()], [sqlite3_create_function16()], or
  4123 ** [sqlite3_create_function_v2()].
  4124 */
  4125 #define SQLITE_DETERMINISTIC    0x800
  4126 
  4127 /*
  4128 ** CAPI3REF: Deprecated Functions
  4129 ** DEPRECATED
  4130 **
  4131 ** These functions are [deprecated].  In order to maintain
  4132 ** backwards compatibility with older code, these functions continue 
  4133 ** to be supported.  However, new applications should avoid
  4134 ** the use of these functions.  To help encourage people to avoid
  4135 ** using these functions, we are not going to tell you what they do.
  4136 */
  4137 #ifndef SQLITE_OMIT_DEPRECATED
  4138 SQLITE_API SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*);
  4139 SQLITE_API SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*);
  4140 SQLITE_API SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);
  4141 SQLITE_API SQLITE_DEPRECATED int sqlite3_global_recover(void);
  4142 SQLITE_API SQLITE_DEPRECATED void sqlite3_thread_cleanup(void);
  4143 SQLITE_API SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),
  4144                       void*,sqlite3_int64);
  4145 #endif
  4146 
  4147 /*
  4148 ** CAPI3REF: Obtaining SQL Function Parameter Values
  4149 **
  4150 ** The C-language implementation of SQL functions and aggregates uses
  4151 ** this set of interface routines to access the parameter values on
  4152 ** the function or aggregate.
  4153 **
  4154 ** The xFunc (for scalar functions) or xStep (for aggregates) parameters
  4155 ** to [sqlite3_create_function()] and [sqlite3_create_function16()]
  4156 ** define callbacks that implement the SQL functions and aggregates.
  4157 ** The 3rd parameter to these callbacks is an array of pointers to
  4158 ** [protected sqlite3_value] objects.  There is one [sqlite3_value] object for
  4159 ** each parameter to the SQL function.  These routines are used to
  4160 ** extract values from the [sqlite3_value] objects.
  4161 **
  4162 ** These routines work only with [protected sqlite3_value] objects.
  4163 ** Any attempt to use these routines on an [unprotected sqlite3_value]
  4164 ** object results in undefined behavior.
  4165 **
  4166 ** ^These routines work just like the corresponding [column access functions]
  4167 ** except that  these routines take a single [protected sqlite3_value] object
  4168 ** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
  4169 **
  4170 ** ^The sqlite3_value_text16() interface extracts a UTF-16 string
  4171 ** in the native byte-order of the host machine.  ^The
  4172 ** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
  4173 ** extract UTF-16 strings as big-endian and little-endian respectively.
  4174 **
  4175 ** ^(The sqlite3_value_numeric_type() interface attempts to apply
  4176 ** numeric affinity to the value.  This means that an attempt is
  4177 ** made to convert the value to an integer or floating point.  If
  4178 ** such a conversion is possible without loss of information (in other
  4179 ** words, if the value is a string that looks like a number)
  4180 ** then the conversion is performed.  Otherwise no conversion occurs.
  4181 ** The [SQLITE_INTEGER | datatype] after conversion is returned.)^
  4182 **
  4183 ** Please pay particular attention to the fact that the pointer returned
  4184 ** from [sqlite3_value_blob()], [sqlite3_value_text()], or
  4185 ** [sqlite3_value_text16()] can be invalidated by a subsequent call to
  4186 ** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
  4187 ** or [sqlite3_value_text16()].
  4188 **
  4189 ** These routines must be called from the same thread as
  4190 ** the SQL function that supplied the [sqlite3_value*] parameters.
  4191 */
  4192 SQLITE_API const void *sqlite3_value_blob(sqlite3_value*);
  4193 SQLITE_API int sqlite3_value_bytes(sqlite3_value*);
  4194 SQLITE_API int sqlite3_value_bytes16(sqlite3_value*);
  4195 SQLITE_API double sqlite3_value_double(sqlite3_value*);
  4196 SQLITE_API int sqlite3_value_int(sqlite3_value*);
  4197 SQLITE_API sqlite3_int64 sqlite3_value_int64(sqlite3_value*);
  4198 SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value*);
  4199 SQLITE_API const void *sqlite3_value_text16(sqlite3_value*);
  4200 SQLITE_API const void *sqlite3_value_text16le(sqlite3_value*);
  4201 SQLITE_API const void *sqlite3_value_text16be(sqlite3_value*);
  4202 SQLITE_API int sqlite3_value_type(sqlite3_value*);
  4203 SQLITE_API int sqlite3_value_numeric_type(sqlite3_value*);
  4204 
  4205 /*
  4206 ** CAPI3REF: Obtain Aggregate Function Context
  4207 **
  4208 ** Implementations of aggregate SQL functions use this
  4209 ** routine to allocate memory for storing their state.
  4210 **
  4211 ** ^The first time the sqlite3_aggregate_context(C,N) routine is called 
  4212 ** for a particular aggregate function, SQLite
  4213 ** allocates N of memory, zeroes out that memory, and returns a pointer
  4214 ** to the new memory. ^On second and subsequent calls to
  4215 ** sqlite3_aggregate_context() for the same aggregate function instance,
  4216 ** the same buffer is returned.  Sqlite3_aggregate_context() is normally
  4217 ** called once for each invocation of the xStep callback and then one
  4218 ** last time when the xFinal callback is invoked.  ^(When no rows match
  4219 ** an aggregate query, the xStep() callback of the aggregate function
  4220 ** implementation is never called and xFinal() is called exactly once.
  4221 ** In those cases, sqlite3_aggregate_context() might be called for the
  4222 ** first time from within xFinal().)^
  4223 **
  4224 ** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer 
  4225 ** when first called if N is less than or equal to zero or if a memory
  4226 ** allocate error occurs.
  4227 **
  4228 ** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is
  4229 ** determined by the N parameter on first successful call.  Changing the
  4230 ** value of N in subsequent call to sqlite3_aggregate_context() within
  4231 ** the same aggregate function instance will not resize the memory
  4232 ** allocation.)^  Within the xFinal callback, it is customary to set
  4233 ** N=0 in calls to sqlite3_aggregate_context(C,N) so that no 
  4234 ** pointless memory allocations occur.
  4235 **
  4236 ** ^SQLite automatically frees the memory allocated by 
  4237 ** sqlite3_aggregate_context() when the aggregate query concludes.
  4238 **
  4239 ** The first parameter must be a copy of the
  4240 ** [sqlite3_context | SQL function context] that is the first parameter
  4241 ** to the xStep or xFinal callback routine that implements the aggregate
  4242 ** function.
  4243 **
  4244 ** This routine must be called from the same thread in which
  4245 ** the aggregate SQL function is running.
  4246 */
  4247 SQLITE_API void *sqlite3_aggregate_context(sqlite3_context*, int nBytes);
  4248 
  4249 /*
  4250 ** CAPI3REF: User Data For Functions
  4251 **
  4252 ** ^The sqlite3_user_data() interface returns a copy of
  4253 ** the pointer that was the pUserData parameter (the 5th parameter)
  4254 ** of the [sqlite3_create_function()]
  4255 ** and [sqlite3_create_function16()] routines that originally
  4256 ** registered the application defined function.
  4257 **
  4258 ** This routine must be called from the same thread in which
  4259 ** the application-defined function is running.
  4260 */
  4261 SQLITE_API void *sqlite3_user_data(sqlite3_context*);
  4262 
  4263 /*
  4264 ** CAPI3REF: Database Connection For Functions
  4265 **
  4266 ** ^The sqlite3_context_db_handle() interface returns a copy of
  4267 ** the pointer to the [database connection] (the 1st parameter)
  4268 ** of the [sqlite3_create_function()]
  4269 ** and [sqlite3_create_function16()] routines that originally
  4270 ** registered the application defined function.
  4271 */
  4272 SQLITE_API sqlite3 *sqlite3_context_db_handle(sqlite3_context*);
  4273 
  4274 /*
  4275 ** CAPI3REF: Function Auxiliary Data
  4276 **
  4277 ** These functions may be used by (non-aggregate) SQL functions to
  4278 ** associate metadata with argument values. If the same value is passed to
  4279 ** multiple invocations of the same SQL function during query execution, under
  4280 ** some circumstances the associated metadata may be preserved.  An example
  4281 ** of where this might be useful is in a regular-expression matching
  4282 ** function. The compiled version of the regular expression can be stored as
  4283 ** metadata associated with the pattern string.  
  4284 ** Then as long as the pattern string remains the same,
  4285 ** the compiled regular expression can be reused on multiple
  4286 ** invocations of the same function.
  4287 **
  4288 ** ^The sqlite3_get_auxdata() interface returns a pointer to the metadata
  4289 ** associated by the sqlite3_set_auxdata() function with the Nth argument
  4290 ** value to the application-defined function. ^If there is no metadata
  4291 ** associated with the function argument, this sqlite3_get_auxdata() interface
  4292 ** returns a NULL pointer.
  4293 **
  4294 ** ^The sqlite3_set_auxdata(C,N,P,X) interface saves P as metadata for the N-th
  4295 ** argument of the application-defined function.  ^Subsequent
  4296 ** calls to sqlite3_get_auxdata(C,N) return P from the most recent
  4297 ** sqlite3_set_auxdata(C,N,P,X) call if the metadata is still valid or
  4298 ** NULL if the metadata has been discarded.
  4299 ** ^After each call to sqlite3_set_auxdata(C,N,P,X) where X is not NULL,
  4300 ** SQLite will invoke the destructor function X with parameter P exactly
  4301 ** once, when the metadata is discarded.
  4302 ** SQLite is free to discard the metadata at any time, including: <ul>
  4303 ** <li> when the corresponding function parameter changes, or
  4304 ** <li> when [sqlite3_reset()] or [sqlite3_finalize()] is called for the
  4305 **      SQL statement, or
  4306 ** <li> when sqlite3_set_auxdata() is invoked again on the same parameter, or
  4307 ** <li> during the original sqlite3_set_auxdata() call when a memory 
  4308 **      allocation error occurs. </ul>)^
  4309 **
  4310 ** Note the last bullet in particular.  The destructor X in 
  4311 ** sqlite3_set_auxdata(C,N,P,X) might be called immediately, before the
  4312 ** sqlite3_set_auxdata() interface even returns.  Hence sqlite3_set_auxdata()
  4313 ** should be called near the end of the function implementation and the
  4314 ** function implementation should not make any use of P after
  4315 ** sqlite3_set_auxdata() has been called.
  4316 **
  4317 ** ^(In practice, metadata is preserved between function calls for
  4318 ** function parameters that are compile-time constants, including literal
  4319 ** values and [parameters] and expressions composed from the same.)^
  4320 **
  4321 ** These routines must be called from the same thread in which
  4322 ** the SQL function is running.
  4323 */
  4324 SQLITE_API void *sqlite3_get_auxdata(sqlite3_context*, int N);
  4325 SQLITE_API void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));
  4326 
  4327 
  4328 /*
  4329 ** CAPI3REF: Constants Defining Special Destructor Behavior
  4330 **
  4331 ** These are special values for the destructor that is passed in as the
  4332 ** final argument to routines like [sqlite3_result_blob()].  ^If the destructor
  4333 ** argument is SQLITE_STATIC, it means that the content pointer is constant
  4334 ** and will never change.  It does not need to be destroyed.  ^The
  4335 ** SQLITE_TRANSIENT value means that the content will likely change in
  4336 ** the near future and that SQLite should make its own private copy of
  4337 ** the content before returning.
  4338 **
  4339 ** The typedef is necessary to work around problems in certain
  4340 ** C++ compilers.
  4341 */
  4342 typedef void (*sqlite3_destructor_type)(void*);
  4343 #define SQLITE_STATIC      ((sqlite3_destructor_type)0)
  4344 #define SQLITE_TRANSIENT   ((sqlite3_destructor_type)-1)
  4345 
  4346 /*
  4347 ** CAPI3REF: Setting The Result Of An SQL Function
  4348 **
  4349 ** These routines are used by the xFunc or xFinal callbacks that
  4350 ** implement SQL functions and aggregates.  See
  4351 ** [sqlite3_create_function()] and [sqlite3_create_function16()]
  4352 ** for additional information.
  4353 **
  4354 ** These functions work very much like the [parameter binding] family of
  4355 ** functions used to bind values to host parameters in prepared statements.
  4356 ** Refer to the [SQL parameter] documentation for additional information.
  4357 **
  4358 ** ^The sqlite3_result_blob() interface sets the result from
  4359 ** an application-defined function to be the BLOB whose content is pointed
  4360 ** to by the second parameter and which is N bytes long where N is the
  4361 ** third parameter.
  4362 **
  4363 ** ^The sqlite3_result_zeroblob() interfaces set the result of
  4364 ** the application-defined function to be a BLOB containing all zero
  4365 ** bytes and N bytes in size, where N is the value of the 2nd parameter.
  4366 **
  4367 ** ^The sqlite3_result_double() interface sets the result from
  4368 ** an application-defined function to be a floating point value specified
  4369 ** by its 2nd argument.
  4370 **
  4371 ** ^The sqlite3_result_error() and sqlite3_result_error16() functions
  4372 ** cause the implemented SQL function to throw an exception.
  4373 ** ^SQLite uses the string pointed to by the
  4374 ** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
  4375 ** as the text of an error message.  ^SQLite interprets the error
  4376 ** message string from sqlite3_result_error() as UTF-8. ^SQLite
  4377 ** interprets the string from sqlite3_result_error16() as UTF-16 in native
  4378 ** byte order.  ^If the third parameter to sqlite3_result_error()
  4379 ** or sqlite3_result_error16() is negative then SQLite takes as the error
  4380 ** message all text up through the first zero character.
  4381 ** ^If the third parameter to sqlite3_result_error() or
  4382 ** sqlite3_result_error16() is non-negative then SQLite takes that many
  4383 ** bytes (not characters) from the 2nd parameter as the error message.
  4384 ** ^The sqlite3_result_error() and sqlite3_result_error16()
  4385 ** routines make a private copy of the error message text before
  4386 ** they return.  Hence, the calling function can deallocate or
  4387 ** modify the text after they return without harm.
  4388 ** ^The sqlite3_result_error_code() function changes the error code
  4389 ** returned by SQLite as a result of an error in a function.  ^By default,
  4390 ** the error code is SQLITE_ERROR.  ^A subsequent call to sqlite3_result_error()
  4391 ** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
  4392 **
  4393 ** ^The sqlite3_result_error_toobig() interface causes SQLite to throw an
  4394 ** error indicating that a string or BLOB is too long to represent.
  4395 **
  4396 ** ^The sqlite3_result_error_nomem() interface causes SQLite to throw an
  4397 ** error indicating that a memory allocation failed.
  4398 **
  4399 ** ^The sqlite3_result_int() interface sets the return value
  4400 ** of the application-defined function to be the 32-bit signed integer
  4401 ** value given in the 2nd argument.
  4402 ** ^The sqlite3_result_int64() interface sets the return value
  4403 ** of the application-defined function to be the 64-bit signed integer
  4404 ** value given in the 2nd argument.
  4405 **
  4406 ** ^The sqlite3_result_null() interface sets the return value
  4407 ** of the application-defined function to be NULL.
  4408 **
  4409 ** ^The sqlite3_result_text(), sqlite3_result_text16(),
  4410 ** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
  4411 ** set the return value of the application-defined function to be
  4412 ** a text string which is represented as UTF-8, UTF-16 native byte order,
  4413 ** UTF-16 little endian, or UTF-16 big endian, respectively.
  4414 ** ^SQLite takes the text result from the application from
  4415 ** the 2nd parameter of the sqlite3_result_text* interfaces.
  4416 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
  4417 ** is negative, then SQLite takes result text from the 2nd parameter
  4418 ** through the first zero character.
  4419 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
  4420 ** is non-negative, then as many bytes (not characters) of the text
  4421 ** pointed to by the 2nd parameter are taken as the application-defined
  4422 ** function result.  If the 3rd parameter is non-negative, then it
  4423 ** must be the byte offset into the string where the NUL terminator would
  4424 ** appear if the string where NUL terminated.  If any NUL characters occur
  4425 ** in the string at a byte offset that is less than the value of the 3rd
  4426 ** parameter, then the resulting string will contain embedded NULs and the
  4427 ** result of expressions operating on strings with embedded NULs is undefined.
  4428 ** ^If the 4th parameter to the sqlite3_result_text* interfaces
  4429 ** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
  4430 ** function as the destructor on the text or BLOB result when it has
  4431 ** finished using that result.
  4432 ** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
  4433 ** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
  4434 ** assumes that the text or BLOB result is in constant space and does not
  4435 ** copy the content of the parameter nor call a destructor on the content
  4436 ** when it has finished using that result.
  4437 ** ^If the 4th parameter to the sqlite3_result_text* interfaces
  4438 ** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
  4439 ** then SQLite makes a copy of the result into space obtained from
  4440 ** from [sqlite3_malloc()] before it returns.
  4441 **
  4442 ** ^The sqlite3_result_value() interface sets the result of
  4443 ** the application-defined function to be a copy the
  4444 ** [unprotected sqlite3_value] object specified by the 2nd parameter.  ^The
  4445 ** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
  4446 ** so that the [sqlite3_value] specified in the parameter may change or
  4447 ** be deallocated after sqlite3_result_value() returns without harm.
  4448 ** ^A [protected sqlite3_value] object may always be used where an
  4449 ** [unprotected sqlite3_value] object is required, so either
  4450 ** kind of [sqlite3_value] object can be used with this interface.
  4451 **
  4452 ** If these routines are called from within the different thread
  4453 ** than the one containing the application-defined function that received
  4454 ** the [sqlite3_context] pointer, the results are undefined.
  4455 */
  4456 SQLITE_API void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
  4457 SQLITE_API void sqlite3_result_double(sqlite3_context*, double);
  4458 SQLITE_API void sqlite3_result_error(sqlite3_context*, const char*, int);
  4459 SQLITE_API void sqlite3_result_error16(sqlite3_context*, const void*, int);
  4460 SQLITE_API void sqlite3_result_error_toobig(sqlite3_context*);
  4461 SQLITE_API void sqlite3_result_error_nomem(sqlite3_context*);
  4462 SQLITE_API void sqlite3_result_error_code(sqlite3_context*, int);
  4463 SQLITE_API void sqlite3_result_int(sqlite3_context*, int);
  4464 SQLITE_API void sqlite3_result_int64(sqlite3_context*, sqlite3_int64);
  4465 SQLITE_API void sqlite3_result_null(sqlite3_context*);
  4466 SQLITE_API void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
  4467 SQLITE_API void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
  4468 SQLITE_API void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
  4469 SQLITE_API void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
  4470 SQLITE_API void sqlite3_result_value(sqlite3_context*, sqlite3_value*);
  4471 SQLITE_API void sqlite3_result_zeroblob(sqlite3_context*, int n);
  4472 
  4473 /*
  4474 ** CAPI3REF: Define New Collating Sequences
  4475 **
  4476 ** ^These functions add, remove, or modify a [collation] associated
  4477 ** with the [database connection] specified as the first argument.
  4478 **
  4479 ** ^The name of the collation is a UTF-8 string
  4480 ** for sqlite3_create_collation() and sqlite3_create_collation_v2()
  4481 ** and a UTF-16 string in native byte order for sqlite3_create_collation16().
  4482 ** ^Collation names that compare equal according to [sqlite3_strnicmp()] are
  4483 ** considered to be the same name.
  4484 **
  4485 ** ^(The third argument (eTextRep) must be one of the constants:
  4486 ** <ul>
  4487 ** <li> [SQLITE_UTF8],
  4488 ** <li> [SQLITE_UTF16LE],
  4489 ** <li> [SQLITE_UTF16BE],
  4490 ** <li> [SQLITE_UTF16], or
  4491 ** <li> [SQLITE_UTF16_ALIGNED].
  4492 ** </ul>)^
  4493 ** ^The eTextRep argument determines the encoding of strings passed
  4494 ** to the collating function callback, xCallback.
  4495 ** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep
  4496 ** force strings to be UTF16 with native byte order.
  4497 ** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin
  4498 ** on an even byte address.
  4499 **
  4500 ** ^The fourth argument, pArg, is an application data pointer that is passed
  4501 ** through as the first argument to the collating function callback.
  4502 **
  4503 ** ^The fifth argument, xCallback, is a pointer to the collating function.
  4504 ** ^Multiple collating functions can be registered using the same name but
  4505 ** with different eTextRep parameters and SQLite will use whichever
  4506 ** function requires the least amount of data transformation.
  4507 ** ^If the xCallback argument is NULL then the collating function is
  4508 ** deleted.  ^When all collating functions having the same name are deleted,
  4509 ** that collation is no longer usable.
  4510 **
  4511 ** ^The collating function callback is invoked with a copy of the pArg 
  4512 ** application data pointer and with two strings in the encoding specified
  4513 ** by the eTextRep argument.  The collating function must return an
  4514 ** integer that is negative, zero, or positive
  4515 ** if the first string is less than, equal to, or greater than the second,
  4516 ** respectively.  A collating function must always return the same answer
  4517 ** given the same inputs.  If two or more collating functions are registered
  4518 ** to the same collation name (using different eTextRep values) then all
  4519 ** must give an equivalent answer when invoked with equivalent strings.
  4520 ** The collating function must obey the following properties for all
  4521 ** strings A, B, and C:
  4522 **
  4523 ** <ol>
  4524 ** <li> If A==B then B==A.
  4525 ** <li> If A==B and B==C then A==C.
  4526 ** <li> If A&lt;B THEN B&gt;A.
  4527 ** <li> If A&lt;B and B&lt;C then A&lt;C.
  4528 ** </ol>
  4529 **
  4530 ** If a collating function fails any of the above constraints and that
  4531 ** collating function is  registered and used, then the behavior of SQLite
  4532 ** is undefined.
  4533 **
  4534 ** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation()
  4535 ** with the addition that the xDestroy callback is invoked on pArg when
  4536 ** the collating function is deleted.
  4537 ** ^Collating functions are deleted when they are overridden by later
  4538 ** calls to the collation creation functions or when the
  4539 ** [database connection] is closed using [sqlite3_close()].
  4540 **
  4541 ** ^The xDestroy callback is <u>not</u> called if the 
  4542 ** sqlite3_create_collation_v2() function fails.  Applications that invoke
  4543 ** sqlite3_create_collation_v2() with a non-NULL xDestroy argument should 
  4544 ** check the return code and dispose of the application data pointer
  4545 ** themselves rather than expecting SQLite to deal with it for them.
  4546 ** This is different from every other SQLite interface.  The inconsistency 
  4547 ** is unfortunate but cannot be changed without breaking backwards 
  4548 ** compatibility.
  4549 **
  4550 ** See also:  [sqlite3_collation_needed()] and [sqlite3_collation_needed16()].
  4551 */
  4552 SQLITE_API int sqlite3_create_collation(
  4553   sqlite3*, 
  4554   const char *zName, 
  4555   int eTextRep, 
  4556   void *pArg,
  4557   int(*xCompare)(void*,int,const void*,int,const void*)
  4558 );
  4559 SQLITE_API int sqlite3_create_collation_v2(
  4560   sqlite3*, 
  4561   const char *zName, 
  4562   int eTextRep, 
  4563   void *pArg,
  4564   int(*xCompare)(void*,int,const void*,int,const void*),
  4565   void(*xDestroy)(void*)
  4566 );
  4567 SQLITE_API int sqlite3_create_collation16(
  4568   sqlite3*, 
  4569   const void *zName,
  4570   int eTextRep, 
  4571   void *pArg,
  4572   int(*xCompare)(void*,int,const void*,int,const void*)
  4573 );
  4574 
  4575 /*
  4576 ** CAPI3REF: Collation Needed Callbacks
  4577 **
  4578 ** ^To avoid having to register all collation sequences before a database
  4579 ** can be used, a single callback function may be registered with the
  4580 ** [database connection] to be invoked whenever an undefined collation
  4581 ** sequence is required.
  4582 **
  4583 ** ^If the function is registered using the sqlite3_collation_needed() API,
  4584 ** then it is passed the names of undefined collation sequences as strings
  4585 ** encoded in UTF-8. ^If sqlite3_collation_needed16() is used,
  4586 ** the names are passed as UTF-16 in machine native byte order.
  4587 ** ^A call to either function replaces the existing collation-needed callback.
  4588 **
  4589 ** ^(When the callback is invoked, the first argument passed is a copy
  4590 ** of the second argument to sqlite3_collation_needed() or
  4591 ** sqlite3_collation_needed16().  The second argument is the database
  4592 ** connection.  The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
  4593 ** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
  4594 ** sequence function required.  The fourth parameter is the name of the
  4595 ** required collation sequence.)^
  4596 **
  4597 ** The callback function should register the desired collation using
  4598 ** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
  4599 ** [sqlite3_create_collation_v2()].
  4600 */
  4601 SQLITE_API int sqlite3_collation_needed(
  4602   sqlite3*, 
  4603   void*, 
  4604   void(*)(void*,sqlite3*,int eTextRep,const char*)
  4605 );
  4606 SQLITE_API int sqlite3_collation_needed16(
  4607   sqlite3*, 
  4608   void*,
  4609   void(*)(void*,sqlite3*,int eTextRep,const void*)
  4610 );
  4611 
  4612 #ifdef SQLITE_HAS_CODEC
  4613 /*
  4614 ** Specify the key for an encrypted database.  This routine should be
  4615 ** called right after sqlite3_open().
  4616 **
  4617 ** The code to implement this API is not available in the public release
  4618 ** of SQLite.
  4619 */
  4620 SQLITE_API int sqlite3_key(
  4621   sqlite3 *db,                   /* Database to be rekeyed */
  4622   const void *pKey, int nKey     /* The key */
  4623 );
  4624 SQLITE_API int sqlite3_key_v2(
  4625   sqlite3 *db,                   /* Database to be rekeyed */
  4626   const char *zDbName,           /* Name of the database */
  4627   const void *pKey, int nKey     /* The key */
  4628 );
  4629 
  4630 /*
  4631 ** Change the key on an open database.  If the current database is not
  4632 ** encrypted, this routine will encrypt it.  If pNew==0 or nNew==0, the
  4633 ** database is decrypted.
  4634 **
  4635 ** The code to implement this API is not available in the public release
  4636 ** of SQLite.
  4637 */
  4638 SQLITE_API int sqlite3_rekey(
  4639   sqlite3 *db,                   /* Database to be rekeyed */
  4640   const void *pKey, int nKey     /* The new key */
  4641 );
  4642 SQLITE_API int sqlite3_rekey_v2(
  4643   sqlite3 *db,                   /* Database to be rekeyed */
  4644   const char *zDbName,           /* Name of the database */
  4645   const void *pKey, int nKey     /* The new key */
  4646 );
  4647 
  4648 /*
  4649 ** Specify the activation key for a SEE database.  Unless 
  4650 ** activated, none of the SEE routines will work.
  4651 */
  4652 SQLITE_API void sqlite3_activate_see(
  4653   const char *zPassPhrase        /* Activation phrase */
  4654 );
  4655 #endif
  4656 
  4657 #ifdef SQLITE_ENABLE_CEROD
  4658 /*
  4659 ** Specify the activation key for a CEROD database.  Unless 
  4660 ** activated, none of the CEROD routines will work.
  4661 */
  4662 SQLITE_API void sqlite3_activate_cerod(
  4663   const char *zPassPhrase        /* Activation phrase */
  4664 );
  4665 #endif
  4666 
  4667 /*
  4668 ** CAPI3REF: Suspend Execution For A Short Time
  4669 **
  4670 ** The sqlite3_sleep() function causes the current thread to suspend execution
  4671 ** for at least a number of milliseconds specified in its parameter.
  4672 **
  4673 ** If the operating system does not support sleep requests with
  4674 ** millisecond time resolution, then the time will be rounded up to
  4675 ** the nearest second. The number of milliseconds of sleep actually
  4676 ** requested from the operating system is returned.
  4677 **
  4678 ** ^SQLite implements this interface by calling the xSleep()
  4679 ** method of the default [sqlite3_vfs] object.  If the xSleep() method
  4680 ** of the default VFS is not implemented correctly, or not implemented at
  4681 ** all, then the behavior of sqlite3_sleep() may deviate from the description
  4682 ** in the previous paragraphs.
  4683 */
  4684 SQLITE_API int sqlite3_sleep(int);
  4685 
  4686 /*
  4687 ** CAPI3REF: Name Of The Folder Holding Temporary Files
  4688 **
  4689 ** ^(If this global variable is made to point to a string which is
  4690 ** the name of a folder (a.k.a. directory), then all temporary files
  4691 ** created by SQLite when using a built-in [sqlite3_vfs | VFS]
  4692 ** will be placed in that directory.)^  ^If this variable
  4693 ** is a NULL pointer, then SQLite performs a search for an appropriate
  4694 ** temporary file directory.
  4695 **
  4696 ** Applications are strongly discouraged from using this global variable.
  4697 ** It is required to set a temporary folder on Windows Runtime (WinRT).
  4698 ** But for all other platforms, it is highly recommended that applications
  4699 ** neither read nor write this variable.  This global variable is a relic
  4700 ** that exists for backwards compatibility of legacy applications and should
  4701 ** be avoided in new projects.
  4702 **
  4703 ** It is not safe to read or modify this variable in more than one
  4704 ** thread at a time.  It is not safe to read or modify this variable
  4705 ** if a [database connection] is being used at the same time in a separate
  4706 ** thread.
  4707 ** It is intended that this variable be set once
  4708 ** as part of process initialization and before any SQLite interface
  4709 ** routines have been called and that this variable remain unchanged
  4710 ** thereafter.
  4711 **
  4712 ** ^The [temp_store_directory pragma] may modify this variable and cause
  4713 ** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
  4714 ** the [temp_store_directory pragma] always assumes that any string
  4715 ** that this variable points to is held in memory obtained from 
  4716 ** [sqlite3_malloc] and the pragma may attempt to free that memory
  4717 ** using [sqlite3_free].
  4718 ** Hence, if this variable is modified directly, either it should be
  4719 ** made NULL or made to point to memory obtained from [sqlite3_malloc]
  4720 ** or else the use of the [temp_store_directory pragma] should be avoided.
  4721 ** Except when requested by the [temp_store_directory pragma], SQLite
  4722 ** does not free the memory that sqlite3_temp_directory points to.  If
  4723 ** the application wants that memory to be freed, it must do
  4724 ** so itself, taking care to only do so after all [database connection]
  4725 ** objects have been destroyed.
  4726 **
  4727 ** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
  4728 ** prior to calling [sqlite3_open] or [sqlite3_open_v2].  Otherwise, various
  4729 ** features that require the use of temporary files may fail.  Here is an
  4730 ** example of how to do this using C++ with the Windows Runtime:
  4731 **
  4732 ** <blockquote><pre>
  4733 ** LPCWSTR zPath = Windows::Storage::ApplicationData::Current->
  4734 ** &nbsp;     TemporaryFolder->Path->Data();
  4735 ** char zPathBuf&#91;MAX_PATH + 1&#93;;
  4736 ** memset(zPathBuf, 0, sizeof(zPathBuf));
  4737 ** WideCharToMultiByte(CP_UTF8, 0, zPath, -1, zPathBuf, sizeof(zPathBuf),
  4738 ** &nbsp;     NULL, NULL);
  4739 ** sqlite3_temp_directory = sqlite3_mprintf("%s", zPathBuf);
  4740 ** </pre></blockquote>
  4741 */
  4742 SQLITE_API SQLITE_EXTERN char *sqlite3_temp_directory;
  4743 
  4744 /*
  4745 ** CAPI3REF: Name Of The Folder Holding Database Files
  4746 **
  4747 ** ^(If this global variable is made to point to a string which is
  4748 ** the name of a folder (a.k.a. directory), then all database files
  4749 ** specified with a relative pathname and created or accessed by
  4750 ** SQLite when using a built-in windows [sqlite3_vfs | VFS] will be assumed
  4751 ** to be relative to that directory.)^ ^If this variable is a NULL
  4752 ** pointer, then SQLite assumes that all database files specified
  4753 ** with a relative pathname are relative to the current directory
  4754 ** for the process.  Only the windows VFS makes use of this global
  4755 ** variable; it is ignored by the unix VFS.
  4756 **
  4757 ** Changing the value of this variable while a database connection is
  4758 ** open can result in a corrupt database.
  4759 **
  4760 ** It is not safe to read or modify this variable in more than one
  4761 ** thread at a time.  It is not safe to read or modify this variable
  4762 ** if a [database connection] is being used at the same time in a separate
  4763 ** thread.
  4764 ** It is intended that this variable be set once
  4765 ** as part of process initialization and before any SQLite interface
  4766 ** routines have been called and that this variable remain unchanged
  4767 ** thereafter.
  4768 **
  4769 ** ^The [data_store_directory pragma] may modify this variable and cause
  4770 ** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
  4771 ** the [data_store_directory pragma] always assumes that any string
  4772 ** that this variable points to is held in memory obtained from 
  4773 ** [sqlite3_malloc] and the pragma may attempt to free that memory
  4774 ** using [sqlite3_free].
  4775 ** Hence, if this variable is modified directly, either it should be
  4776 ** made NULL or made to point to memory obtained from [sqlite3_malloc]
  4777 ** or else the use of the [data_store_directory pragma] should be avoided.
  4778 */
  4779 SQLITE_API SQLITE_EXTERN char *sqlite3_data_directory;
  4780 
  4781 /*
  4782 ** CAPI3REF: Test For Auto-Commit Mode
  4783 ** KEYWORDS: {autocommit mode}
  4784 **
  4785 ** ^The sqlite3_get_autocommit() interface returns non-zero or
  4786 ** zero if the given database connection is or is not in autocommit mode,
  4787 ** respectively.  ^Autocommit mode is on by default.
  4788 ** ^Autocommit mode is disabled by a [BEGIN] statement.
  4789 ** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
  4790 **
  4791 ** If certain kinds of errors occur on a statement within a multi-statement
  4792 ** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
  4793 ** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the
  4794 ** transaction might be rolled back automatically.  The only way to
  4795 ** find out whether SQLite automatically rolled back the transaction after
  4796 ** an error is to use this function.
  4797 **
  4798 ** If another thread changes the autocommit status of the database
  4799 ** connection while this routine is running, then the return value
  4800 ** is undefined.
  4801 */
  4802 SQLITE_API int sqlite3_get_autocommit(sqlite3*);
  4803 
  4804 /*
  4805 ** CAPI3REF: Find The Database Handle Of A Prepared Statement
  4806 **
  4807 ** ^The sqlite3_db_handle interface returns the [database connection] handle
  4808 ** to which a [prepared statement] belongs.  ^The [database connection]
  4809 ** returned by sqlite3_db_handle is the same [database connection]
  4810 ** that was the first argument
  4811 ** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
  4812 ** create the statement in the first place.
  4813 */
  4814 SQLITE_API sqlite3 *sqlite3_db_handle(sqlite3_stmt*);
  4815 
  4816 /*
  4817 ** CAPI3REF: Return The Filename For A Database Connection
  4818 **
  4819 ** ^The sqlite3_db_filename(D,N) interface returns a pointer to a filename
  4820 ** associated with database N of connection D.  ^The main database file
  4821 ** has the name "main".  If there is no attached database N on the database
  4822 ** connection D, or if database N is a temporary or in-memory database, then
  4823 ** a NULL pointer is returned.
  4824 **
  4825 ** ^The filename returned by this function is the output of the
  4826 ** xFullPathname method of the [VFS].  ^In other words, the filename
  4827 ** will be an absolute pathname, even if the filename used
  4828 ** to open the database originally was a URI or relative pathname.
  4829 */
  4830 SQLITE_API const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName);
  4831 
  4832 /*
  4833 ** CAPI3REF: Determine if a database is read-only
  4834 **
  4835 ** ^The sqlite3_db_readonly(D,N) interface returns 1 if the database N
  4836 ** of connection D is read-only, 0 if it is read/write, or -1 if N is not
  4837 ** the name of a database on connection D.
  4838 */
  4839 SQLITE_API int sqlite3_db_readonly(sqlite3 *db, const char *zDbName);
  4840 
  4841 /*
  4842 ** CAPI3REF: Find the next prepared statement
  4843 **
  4844 ** ^This interface returns a pointer to the next [prepared statement] after
  4845 ** pStmt associated with the [database connection] pDb.  ^If pStmt is NULL
  4846 ** then this interface returns a pointer to the first prepared statement
  4847 ** associated with the database connection pDb.  ^If no prepared statement
  4848 ** satisfies the conditions of this routine, it returns NULL.
  4849 **
  4850 ** The [database connection] pointer D in a call to
  4851 ** [sqlite3_next_stmt(D,S)] must refer to an open database
  4852 ** connection and in particular must not be a NULL pointer.
  4853 */
  4854 SQLITE_API sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);
  4855 
  4856 /*
  4857 ** CAPI3REF: Commit And Rollback Notification Callbacks
  4858 **
  4859 ** ^The sqlite3_commit_hook() interface registers a callback
  4860 ** function to be invoked whenever a transaction is [COMMIT | committed].
  4861 ** ^Any callback set by a previous call to sqlite3_commit_hook()
  4862 ** for the same database connection is overridden.
  4863 ** ^The sqlite3_rollback_hook() interface registers a callback
  4864 ** function to be invoked whenever a transaction is [ROLLBACK | rolled back].
  4865 ** ^Any callback set by a previous call to sqlite3_rollback_hook()
  4866 ** for the same database connection is overridden.
  4867 ** ^The pArg argument is passed through to the callback.
  4868 ** ^If the callback on a commit hook function returns non-zero,
  4869 ** then the commit is converted into a rollback.
  4870 **
  4871 ** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions
  4872 ** return the P argument from the previous call of the same function
  4873 ** on the same [database connection] D, or NULL for
  4874 ** the first call for each function on D.
  4875 **
  4876 ** The commit and rollback hook callbacks are not reentrant.
  4877 ** The callback implementation must not do anything that will modify
  4878 ** the database connection that invoked the callback.  Any actions
  4879 ** to modify the database connection must be deferred until after the
  4880 ** completion of the [sqlite3_step()] call that triggered the commit
  4881 ** or rollback hook in the first place.
  4882 ** Note that running any other SQL statements, including SELECT statements,
  4883 ** or merely calling [sqlite3_prepare_v2()] and [sqlite3_step()] will modify
  4884 ** the database connections for the meaning of "modify" in this paragraph.
  4885 **
  4886 ** ^Registering a NULL function disables the callback.
  4887 **
  4888 ** ^When the commit hook callback routine returns zero, the [COMMIT]
  4889 ** operation is allowed to continue normally.  ^If the commit hook
  4890 ** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].
  4891 ** ^The rollback hook is invoked on a rollback that results from a commit
  4892 ** hook returning non-zero, just as it would be with any other rollback.
  4893 **
  4894 ** ^For the purposes of this API, a transaction is said to have been
  4895 ** rolled back if an explicit "ROLLBACK" statement is executed, or
  4896 ** an error or constraint causes an implicit rollback to occur.
  4897 ** ^The rollback callback is not invoked if a transaction is
  4898 ** automatically rolled back because the database connection is closed.
  4899 **
  4900 ** See also the [sqlite3_update_hook()] interface.
  4901 */
  4902 SQLITE_API void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
  4903 SQLITE_API void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
  4904 
  4905 /*
  4906 ** CAPI3REF: Data Change Notification Callbacks
  4907 **
  4908 ** ^The sqlite3_update_hook() interface registers a callback function
  4909 ** with the [database connection] identified by the first argument
  4910 ** to be invoked whenever a row is updated, inserted or deleted in
  4911 ** a rowid table.
  4912 ** ^Any callback set by a previous call to this function
  4913 ** for the same database connection is overridden.
  4914 **
  4915 ** ^The second argument is a pointer to the function to invoke when a
  4916 ** row is updated, inserted or deleted in a rowid table.
  4917 ** ^The first argument to the callback is a copy of the third argument
  4918 ** to sqlite3_update_hook().
  4919 ** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
  4920 ** or [SQLITE_UPDATE], depending on the operation that caused the callback
  4921 ** to be invoked.
  4922 ** ^The third and fourth arguments to the callback contain pointers to the
  4923 ** database and table name containing the affected row.
  4924 ** ^The final callback parameter is the [rowid] of the row.
  4925 ** ^In the case of an update, this is the [rowid] after the update takes place.
  4926 **
  4927 ** ^(The update hook is not invoked when internal system tables are
  4928 ** modified (i.e. sqlite_master and sqlite_sequence).)^
  4929 ** ^The update hook is not invoked when [WITHOUT ROWID] tables are modified.
  4930 **
  4931 ** ^In the current implementation, the update hook
  4932 ** is not invoked when duplication rows are deleted because of an
  4933 ** [ON CONFLICT | ON CONFLICT REPLACE] clause.  ^Nor is the update hook
  4934 ** invoked when rows are deleted using the [truncate optimization].
  4935 ** The exceptions defined in this paragraph might change in a future
  4936 ** release of SQLite.
  4937 **
  4938 ** The update hook implementation must not do anything that will modify
  4939 ** the database connection that invoked the update hook.  Any actions
  4940 ** to modify the database connection must be deferred until after the
  4941 ** completion of the [sqlite3_step()] call that triggered the update hook.
  4942 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  4943 ** database connections for the meaning of "modify" in this paragraph.
  4944 **
  4945 ** ^The sqlite3_update_hook(D,C,P) function
  4946 ** returns the P argument from the previous call
  4947 ** on the same [database connection] D, or NULL for
  4948 ** the first call on D.
  4949 **
  4950 ** See also the [sqlite3_commit_hook()] and [sqlite3_rollback_hook()]
  4951 ** interfaces.
  4952 */
  4953 SQLITE_API void *sqlite3_update_hook(
  4954   sqlite3*, 
  4955   void(*)(void *,int ,char const *,char const *,sqlite3_int64),
  4956   void*
  4957 );
  4958 
  4959 /*
  4960 ** CAPI3REF: Enable Or Disable Shared Pager Cache
  4961 **
  4962 ** ^(This routine enables or disables the sharing of the database cache
  4963 ** and schema data structures between [database connection | connections]
  4964 ** to the same database. Sharing is enabled if the argument is true
  4965 ** and disabled if the argument is false.)^
  4966 **
  4967 ** ^Cache sharing is enabled and disabled for an entire process.
  4968 ** This is a change as of SQLite version 3.5.0. In prior versions of SQLite,
  4969 ** sharing was enabled or disabled for each thread separately.
  4970 **
  4971 ** ^(The cache sharing mode set by this interface effects all subsequent
  4972 ** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
  4973 ** Existing database connections continue use the sharing mode
  4974 ** that was in effect at the time they were opened.)^
  4975 **
  4976 ** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
  4977 ** successfully.  An [error code] is returned otherwise.)^
  4978 **
  4979 ** ^Shared cache is disabled by default. But this might change in
  4980 ** future releases of SQLite.  Applications that care about shared
  4981 ** cache setting should set it explicitly.
  4982 **
  4983 ** This interface is threadsafe on processors where writing a
  4984 ** 32-bit integer is atomic.
  4985 **
  4986 ** See Also:  [SQLite Shared-Cache Mode]
  4987 */
  4988 SQLITE_API int sqlite3_enable_shared_cache(int);
  4989 
  4990 /*
  4991 ** CAPI3REF: Attempt To Free Heap Memory
  4992 **
  4993 ** ^The sqlite3_release_memory() interface attempts to free N bytes
  4994 ** of heap memory by deallocating non-essential memory allocations
  4995 ** held by the database library.   Memory used to cache database
  4996 ** pages to improve performance is an example of non-essential memory.
  4997 ** ^sqlite3_release_memory() returns the number of bytes actually freed,
  4998 ** which might be more or less than the amount requested.
  4999 ** ^The sqlite3_release_memory() routine is a no-op returning zero
  5000 ** if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT].
  5001 **
  5002 ** See also: [sqlite3_db_release_memory()]
  5003 */
  5004 SQLITE_API int sqlite3_release_memory(int);
  5005 
  5006 /*
  5007 ** CAPI3REF: Free Memory Used By A Database Connection
  5008 **
  5009 ** ^The sqlite3_db_release_memory(D) interface attempts to free as much heap
  5010 ** memory as possible from database connection D. Unlike the
  5011 ** [sqlite3_release_memory()] interface, this interface is in effect even
  5012 ** when the [SQLITE_ENABLE_MEMORY_MANAGEMENT] compile-time option is
  5013 ** omitted.
  5014 **
  5015 ** See also: [sqlite3_release_memory()]
  5016 */
  5017 SQLITE_API int sqlite3_db_release_memory(sqlite3*);
  5018 
  5019 /*
  5020 ** CAPI3REF: Impose A Limit On Heap Size
  5021 **
  5022 ** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the
  5023 ** soft limit on the amount of heap memory that may be allocated by SQLite.
  5024 ** ^SQLite strives to keep heap memory utilization below the soft heap
  5025 ** limit by reducing the number of pages held in the page cache
  5026 ** as heap memory usages approaches the limit.
  5027 ** ^The soft heap limit is "soft" because even though SQLite strives to stay
  5028 ** below the limit, it will exceed the limit rather than generate
  5029 ** an [SQLITE_NOMEM] error.  In other words, the soft heap limit 
  5030 ** is advisory only.
  5031 **
  5032 ** ^The return value from sqlite3_soft_heap_limit64() is the size of
  5033 ** the soft heap limit prior to the call, or negative in the case of an
  5034 ** error.  ^If the argument N is negative
  5035 ** then no change is made to the soft heap limit.  Hence, the current
  5036 ** size of the soft heap limit can be determined by invoking
  5037 ** sqlite3_soft_heap_limit64() with a negative argument.
  5038 **
  5039 ** ^If the argument N is zero then the soft heap limit is disabled.
  5040 **
  5041 ** ^(The soft heap limit is not enforced in the current implementation
  5042 ** if one or more of following conditions are true:
  5043 **
  5044 ** <ul>
  5045 ** <li> The soft heap limit is set to zero.
  5046 ** <li> Memory accounting is disabled using a combination of the
  5047 **      [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
  5048 **      the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
  5049 ** <li> An alternative page cache implementation is specified using
  5050 **      [sqlite3_config]([SQLITE_CONFIG_PCACHE2],...).
  5051 ** <li> The page cache allocates from its own memory pool supplied
  5052 **      by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than
  5053 **      from the heap.
  5054 ** </ul>)^
  5055 **
  5056 ** Beginning with SQLite version 3.7.3, the soft heap limit is enforced
  5057 ** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]
  5058 ** compile-time option is invoked.  With [SQLITE_ENABLE_MEMORY_MANAGEMENT],
  5059 ** the soft heap limit is enforced on every memory allocation.  Without
  5060 ** [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced
  5061 ** when memory is allocated by the page cache.  Testing suggests that because
  5062 ** the page cache is the predominate memory user in SQLite, most
  5063 ** applications will achieve adequate soft heap limit enforcement without
  5064 ** the use of [SQLITE_ENABLE_MEMORY_MANAGEMENT].
  5065 **
  5066 ** The circumstances under which SQLite will enforce the soft heap limit may
  5067 ** changes in future releases of SQLite.
  5068 */
  5069 SQLITE_API sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 N);
  5070 
  5071 /*
  5072 ** CAPI3REF: Deprecated Soft Heap Limit Interface
  5073 ** DEPRECATED
  5074 **
  5075 ** This is a deprecated version of the [sqlite3_soft_heap_limit64()]
  5076 ** interface.  This routine is provided for historical compatibility
  5077 ** only.  All new applications should use the
  5078 ** [sqlite3_soft_heap_limit64()] interface rather than this one.
  5079 */
  5080 SQLITE_API SQLITE_DEPRECATED void sqlite3_soft_heap_limit(int N);
  5081 
  5082 
  5083 /*
  5084 ** CAPI3REF: Extract Metadata About A Column Of A Table
  5085 **
  5086 ** ^This routine returns metadata about a specific column of a specific
  5087 ** database table accessible using the [database connection] handle
  5088 ** passed as the first function argument.
  5089 **
  5090 ** ^The column is identified by the second, third and fourth parameters to
  5091 ** this function. ^The second parameter is either the name of the database
  5092 ** (i.e. "main", "temp", or an attached database) containing the specified
  5093 ** table or NULL. ^If it is NULL, then all attached databases are searched
  5094 ** for the table using the same algorithm used by the database engine to
  5095 ** resolve unqualified table references.
  5096 **
  5097 ** ^The third and fourth parameters to this function are the table and column
  5098 ** name of the desired column, respectively. Neither of these parameters
  5099 ** may be NULL.
  5100 **
  5101 ** ^Metadata is returned by writing to the memory locations passed as the 5th
  5102 ** and subsequent parameters to this function. ^Any of these arguments may be
  5103 ** NULL, in which case the corresponding element of metadata is omitted.
  5104 **
  5105 ** ^(<blockquote>
  5106 ** <table border="1">
  5107 ** <tr><th> Parameter <th> Output<br>Type <th>  Description
  5108 **
  5109 ** <tr><td> 5th <td> const char* <td> Data type
  5110 ** <tr><td> 6th <td> const char* <td> Name of default collation sequence
  5111 ** <tr><td> 7th <td> int         <td> True if column has a NOT NULL constraint
  5112 ** <tr><td> 8th <td> int         <td> True if column is part of the PRIMARY KEY
  5113 ** <tr><td> 9th <td> int         <td> True if column is [AUTOINCREMENT]
  5114 ** </table>
  5115 ** </blockquote>)^
  5116 **
  5117 ** ^The memory pointed to by the character pointers returned for the
  5118 ** declaration type and collation sequence is valid only until the next
  5119 ** call to any SQLite API function.
  5120 **
  5121 ** ^If the specified table is actually a view, an [error code] is returned.
  5122 **
  5123 ** ^If the specified column is "rowid", "oid" or "_rowid_" and an
  5124 ** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
  5125 ** parameters are set for the explicitly declared column. ^(If there is no
  5126 ** explicitly declared [INTEGER PRIMARY KEY] column, then the output
  5127 ** parameters are set as follows:
  5128 **
  5129 ** <pre>
  5130 **     data type: "INTEGER"
  5131 **     collation sequence: "BINARY"
  5132 **     not null: 0
  5133 **     primary key: 1
  5134 **     auto increment: 0
  5135 ** </pre>)^
  5136 **
  5137 ** ^(This function may load one or more schemas from database files. If an
  5138 ** error occurs during this process, or if the requested table or column
  5139 ** cannot be found, an [error code] is returned and an error message left
  5140 ** in the [database connection] (to be retrieved using sqlite3_errmsg()).)^
  5141 **
  5142 ** ^This API is only available if the library was compiled with the
  5143 ** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol defined.
  5144 */
  5145 SQLITE_API int sqlite3_table_column_metadata(
  5146   sqlite3 *db,                /* Connection handle */
  5147   const char *zDbName,        /* Database name or NULL */
  5148   const char *zTableName,     /* Table name */
  5149   const char *zColumnName,    /* Column name */
  5150   char const **pzDataType,    /* OUTPUT: Declared data type */
  5151   char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
  5152   int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
  5153   int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
  5154   int *pAutoinc               /* OUTPUT: True if column is auto-increment */
  5155 );
  5156 
  5157 /*
  5158 ** CAPI3REF: Load An Extension
  5159 **
  5160 ** ^This interface loads an SQLite extension library from the named file.
  5161 **
  5162 ** ^The sqlite3_load_extension() interface attempts to load an
  5163 ** [SQLite extension] library contained in the file zFile.  If
  5164 ** the file cannot be loaded directly, attempts are made to load
  5165 ** with various operating-system specific extensions added.
  5166 ** So for example, if "samplelib" cannot be loaded, then names like
  5167 ** "samplelib.so" or "samplelib.dylib" or "samplelib.dll" might
  5168 ** be tried also.
  5169 **
  5170 ** ^The entry point is zProc.
  5171 ** ^(zProc may be 0, in which case SQLite will try to come up with an
  5172 ** entry point name on its own.  It first tries "sqlite3_extension_init".
  5173 ** If that does not work, it constructs a name "sqlite3_X_init" where the
  5174 ** X is consists of the lower-case equivalent of all ASCII alphabetic
  5175 ** characters in the filename from the last "/" to the first following
  5176 ** "." and omitting any initial "lib".)^
  5177 ** ^The sqlite3_load_extension() interface returns
  5178 ** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
  5179 ** ^If an error occurs and pzErrMsg is not 0, then the
  5180 ** [sqlite3_load_extension()] interface shall attempt to
  5181 ** fill *pzErrMsg with error message text stored in memory
  5182 ** obtained from [sqlite3_malloc()]. The calling function
  5183 ** should free this memory by calling [sqlite3_free()].
  5184 **
  5185 ** ^Extension loading must be enabled using
  5186 ** [sqlite3_enable_load_extension()] prior to calling this API,
  5187 ** otherwise an error will be returned.
  5188 **
  5189 ** See also the [load_extension() SQL function].
  5190 */
  5191 SQLITE_API int sqlite3_load_extension(
  5192   sqlite3 *db,          /* Load the extension into this database connection */
  5193   const char *zFile,    /* Name of the shared library containing extension */
  5194   const char *zProc,    /* Entry point.  Derived from zFile if 0 */
  5195   char **pzErrMsg       /* Put error message here if not 0 */
  5196 );
  5197 
  5198 /*
  5199 ** CAPI3REF: Enable Or Disable Extension Loading
  5200 **
  5201 ** ^So as not to open security holes in older applications that are
  5202 ** unprepared to deal with [extension loading], and as a means of disabling
  5203 ** [extension loading] while evaluating user-entered SQL, the following API
  5204 ** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
  5205 **
  5206 ** ^Extension loading is off by default.
  5207 ** ^Call the sqlite3_enable_load_extension() routine with onoff==1
  5208 ** to turn extension loading on and call it with onoff==0 to turn
  5209 ** it back off again.
  5210 */
  5211 SQLITE_API int sqlite3_enable_load_extension(sqlite3 *db, int onoff);
  5212 
  5213 /*
  5214 ** CAPI3REF: Automatically Load Statically Linked Extensions
  5215 **
  5216 ** ^This interface causes the xEntryPoint() function to be invoked for
  5217 ** each new [database connection] that is created.  The idea here is that
  5218 ** xEntryPoint() is the entry point for a statically linked [SQLite extension]
  5219 ** that is to be automatically loaded into all new database connections.
  5220 **
  5221 ** ^(Even though the function prototype shows that xEntryPoint() takes
  5222 ** no arguments and returns void, SQLite invokes xEntryPoint() with three
  5223 ** arguments and expects and integer result as if the signature of the
  5224 ** entry point where as follows:
  5225 **
  5226 ** <blockquote><pre>
  5227 ** &nbsp;  int xEntryPoint(
  5228 ** &nbsp;    sqlite3 *db,
  5229 ** &nbsp;    const char **pzErrMsg,
  5230 ** &nbsp;    const struct sqlite3_api_routines *pThunk
  5231 ** &nbsp;  );
  5232 ** </pre></blockquote>)^
  5233 **
  5234 ** If the xEntryPoint routine encounters an error, it should make *pzErrMsg
  5235 ** point to an appropriate error message (obtained from [sqlite3_mprintf()])
  5236 ** and return an appropriate [error code].  ^SQLite ensures that *pzErrMsg
  5237 ** is NULL before calling the xEntryPoint().  ^SQLite will invoke
  5238 ** [sqlite3_free()] on *pzErrMsg after xEntryPoint() returns.  ^If any
  5239 ** xEntryPoint() returns an error, the [sqlite3_open()], [sqlite3_open16()],
  5240 ** or [sqlite3_open_v2()] call that provoked the xEntryPoint() will fail.
  5241 **
  5242 ** ^Calling sqlite3_auto_extension(X) with an entry point X that is already
  5243 ** on the list of automatic extensions is a harmless no-op. ^No entry point
  5244 ** will be called more than once for each database connection that is opened.
  5245 **
  5246 ** See also: [sqlite3_reset_auto_extension()]
  5247 ** and [sqlite3_cancel_auto_extension()]
  5248 */
  5249 SQLITE_API int sqlite3_auto_extension(void (*xEntryPoint)(void));
  5250 
  5251 /*
  5252 ** CAPI3REF: Cancel Automatic Extension Loading
  5253 **
  5254 ** ^The [sqlite3_cancel_auto_extension(X)] interface unregisters the
  5255 ** initialization routine X that was registered using a prior call to
  5256 ** [sqlite3_auto_extension(X)].  ^The [sqlite3_cancel_auto_extension(X)]
  5257 ** routine returns 1 if initialization routine X was successfully 
  5258 ** unregistered and it returns 0 if X was not on the list of initialization
  5259 ** routines.
  5260 */
  5261 SQLITE_API int sqlite3_cancel_auto_extension(void (*xEntryPoint)(void));
  5262 
  5263 /*
  5264 ** CAPI3REF: Reset Automatic Extension Loading
  5265 **
  5266 ** ^This interface disables all automatic extensions previously
  5267 ** registered using [sqlite3_auto_extension()].
  5268 */
  5269 SQLITE_API void sqlite3_reset_auto_extension(void);
  5270 
  5271 /*
  5272 ** The interface to the virtual-table mechanism is currently considered
  5273 ** to be experimental.  The interface might change in incompatible ways.
  5274 ** If this is a problem for you, do not use the interface at this time.
  5275 **
  5276 ** When the virtual-table mechanism stabilizes, we will declare the
  5277 ** interface fixed, support it indefinitely, and remove this comment.
  5278 */
  5279 
  5280 /*
  5281 ** Structures used by the virtual table interface
  5282 */
  5283 typedef struct sqlite3_vtab sqlite3_vtab;
  5284 typedef struct sqlite3_index_info sqlite3_index_info;
  5285 typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
  5286 typedef struct sqlite3_module sqlite3_module;
  5287 
  5288 /*
  5289 ** CAPI3REF: Virtual Table Object
  5290 ** KEYWORDS: sqlite3_module {virtual table module}
  5291 **
  5292 ** This structure, sometimes called a "virtual table module", 
  5293 ** defines the implementation of a [virtual tables].  
  5294 ** This structure consists mostly of methods for the module.
  5295 **
  5296 ** ^A virtual table module is created by filling in a persistent
  5297 ** instance of this structure and passing a pointer to that instance
  5298 ** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].
  5299 ** ^The registration remains valid until it is replaced by a different
  5300 ** module or until the [database connection] closes.  The content
  5301 ** of this structure must not change while it is registered with
  5302 ** any database connection.
  5303 */
  5304 struct sqlite3_module {
  5305   int iVersion;
  5306   int (*xCreate)(sqlite3*, void *pAux,
  5307                int argc, const char *const*argv,
  5308                sqlite3_vtab **ppVTab, char**);
  5309   int (*xConnect)(sqlite3*, void *pAux,
  5310                int argc, const char *const*argv,
  5311                sqlite3_vtab **ppVTab, char**);
  5312   int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
  5313   int (*xDisconnect)(sqlite3_vtab *pVTab);
  5314   int (*xDestroy)(sqlite3_vtab *pVTab);
  5315   int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
  5316   int (*xClose)(sqlite3_vtab_cursor*);
  5317   int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
  5318                 int argc, sqlite3_value **argv);
  5319   int (*xNext)(sqlite3_vtab_cursor*);
  5320   int (*xEof)(sqlite3_vtab_cursor*);
  5321   int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int);
  5322   int (*xRowid)(sqlite3_vtab_cursor*, sqlite3_int64 *pRowid);
  5323   int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite3_int64 *);
  5324   int (*xBegin)(sqlite3_vtab *pVTab);
  5325   int (*xSync)(sqlite3_vtab *pVTab);
  5326   int (*xCommit)(sqlite3_vtab *pVTab);
  5327   int (*xRollback)(sqlite3_vtab *pVTab);
  5328   int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName,
  5329                        void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
  5330                        void **ppArg);
  5331   int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
  5332   /* The methods above are in version 1 of the sqlite_module object. Those 
  5333   ** below are for version 2 and greater. */
  5334   int (*xSavepoint)(sqlite3_vtab *pVTab, int);
  5335   int (*xRelease)(sqlite3_vtab *pVTab, int);
  5336   int (*xRollbackTo)(sqlite3_vtab *pVTab, int);
  5337 };
  5338 
  5339 /*
  5340 ** CAPI3REF: Virtual Table Indexing Information
  5341 ** KEYWORDS: sqlite3_index_info
  5342 **
  5343 ** The sqlite3_index_info structure and its substructures is used as part
  5344 ** of the [virtual table] interface to
  5345 ** pass information into and receive the reply from the [xBestIndex]
  5346 ** method of a [virtual table module].  The fields under **Inputs** are the
  5347 ** inputs to xBestIndex and are read-only.  xBestIndex inserts its
  5348 ** results into the **Outputs** fields.
  5349 **
  5350 ** ^(The aConstraint[] array records WHERE clause constraints of the form:
  5351 **
  5352 ** <blockquote>column OP expr</blockquote>
  5353 **
  5354 ** where OP is =, &lt;, &lt;=, &gt;, or &gt;=.)^  ^(The particular operator is
  5355 ** stored in aConstraint[].op using one of the
  5356 ** [SQLITE_INDEX_CONSTRAINT_EQ | SQLITE_INDEX_CONSTRAINT_ values].)^
  5357 ** ^(The index of the column is stored in
  5358 ** aConstraint[].iColumn.)^  ^(aConstraint[].usable is TRUE if the
  5359 ** expr on the right-hand side can be evaluated (and thus the constraint
  5360 ** is usable) and false if it cannot.)^
  5361 **
  5362 ** ^The optimizer automatically inverts terms of the form "expr OP column"
  5363 ** and makes other simplifications to the WHERE clause in an attempt to
  5364 ** get as many WHERE clause terms into the form shown above as possible.
  5365 ** ^The aConstraint[] array only reports WHERE clause terms that are
  5366 ** relevant to the particular virtual table being queried.
  5367 **
  5368 ** ^Information about the ORDER BY clause is stored in aOrderBy[].
  5369 ** ^Each term of aOrderBy records a column of the ORDER BY clause.
  5370 **
  5371 ** The [xBestIndex] method must fill aConstraintUsage[] with information
  5372 ** about what parameters to pass to xFilter.  ^If argvIndex>0 then
  5373 ** the right-hand side of the corresponding aConstraint[] is evaluated
  5374 ** and becomes the argvIndex-th entry in argv.  ^(If aConstraintUsage[].omit
  5375 ** is true, then the constraint is assumed to be fully handled by the
  5376 ** virtual table and is not checked again by SQLite.)^
  5377 **
  5378 ** ^The idxNum and idxPtr values are recorded and passed into the
  5379 ** [xFilter] method.
  5380 ** ^[sqlite3_free()] is used to free idxPtr if and only if
  5381 ** needToFreeIdxPtr is true.
  5382 **
  5383 ** ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in
  5384 ** the correct order to satisfy the ORDER BY clause so that no separate
  5385 ** sorting step is required.
  5386 **
  5387 ** ^The estimatedCost value is an estimate of the cost of a particular
  5388 ** strategy. A cost of N indicates that the cost of the strategy is similar
  5389 ** to a linear scan of an SQLite table with N rows. A cost of log(N) 
  5390 ** indicates that the expense of the operation is similar to that of a
  5391 ** binary search on a unique indexed field of an SQLite table with N rows.
  5392 **
  5393 ** ^The estimatedRows value is an estimate of the number of rows that
  5394 ** will be returned by the strategy.
  5395 **
  5396 ** IMPORTANT: The estimatedRows field was added to the sqlite3_index_info
  5397 ** structure for SQLite version 3.8.2. If a virtual table extension is
  5398 ** used with an SQLite version earlier than 3.8.2, the results of attempting 
  5399 ** to read or write the estimatedRows field are undefined (but are likely 
  5400 ** to included crashing the application). The estimatedRows field should
  5401 ** therefore only be used if [sqlite3_libversion_number()] returns a
  5402 ** value greater than or equal to 3008002.
  5403 */
  5404 struct sqlite3_index_info {
  5405   /* Inputs */
  5406   int nConstraint;           /* Number of entries in aConstraint */
  5407   struct sqlite3_index_constraint {
  5408      int iColumn;              /* Column on left-hand side of constraint */
  5409      unsigned char op;         /* Constraint operator */
  5410      unsigned char usable;     /* True if this constraint is usable */
  5411      int iTermOffset;          /* Used internally - xBestIndex should ignore */
  5412   } *aConstraint;            /* Table of WHERE clause constraints */
  5413   int nOrderBy;              /* Number of terms in the ORDER BY clause */
  5414   struct sqlite3_index_orderby {
  5415      int iColumn;              /* Column number */
  5416      unsigned char desc;       /* True for DESC.  False for ASC. */
  5417   } *aOrderBy;               /* The ORDER BY clause */
  5418   /* Outputs */
  5419   struct sqlite3_index_constraint_usage {
  5420     int argvIndex;           /* if >0, constraint is part of argv to xFilter */
  5421     unsigned char omit;      /* Do not code a test for this constraint */
  5422   } *aConstraintUsage;
  5423   int idxNum;                /* Number used to identify the index */
  5424   char *idxStr;              /* String, possibly obtained from sqlite3_malloc */
  5425   int needToFreeIdxStr;      /* Free idxStr using sqlite3_free() if true */
  5426   int orderByConsumed;       /* True if output is already ordered */
  5427   double estimatedCost;           /* Estimated cost of using this index */
  5428   /* Fields below are only available in SQLite 3.8.2 and later */
  5429   sqlite3_int64 estimatedRows;    /* Estimated number of rows returned */
  5430 };
  5431 
  5432 /*
  5433 ** CAPI3REF: Virtual Table Constraint Operator Codes
  5434 **
  5435 ** These macros defined the allowed values for the
  5436 ** [sqlite3_index_info].aConstraint[].op field.  Each value represents
  5437 ** an operator that is part of a constraint term in the wHERE clause of
  5438 ** a query that uses a [virtual table].
  5439 */
  5440 #define SQLITE_INDEX_CONSTRAINT_EQ    2
  5441 #define SQLITE_INDEX_CONSTRAINT_GT    4
  5442 #define SQLITE_INDEX_CONSTRAINT_LE    8
  5443 #define SQLITE_INDEX_CONSTRAINT_LT    16
  5444 #define SQLITE_INDEX_CONSTRAINT_GE    32
  5445 #define SQLITE_INDEX_CONSTRAINT_MATCH 64
  5446 
  5447 /*
  5448 ** CAPI3REF: Register A Virtual Table Implementation
  5449 **
  5450 ** ^These routines are used to register a new [virtual table module] name.
  5451 ** ^Module names must be registered before
  5452 ** creating a new [virtual table] using the module and before using a
  5453 ** preexisting [virtual table] for the module.
  5454 **
  5455 ** ^The module name is registered on the [database connection] specified
  5456 ** by the first parameter.  ^The name of the module is given by the 
  5457 ** second parameter.  ^The third parameter is a pointer to
  5458 ** the implementation of the [virtual table module].   ^The fourth
  5459 ** parameter is an arbitrary client data pointer that is passed through
  5460 ** into the [xCreate] and [xConnect] methods of the virtual table module
  5461 ** when a new virtual table is be being created or reinitialized.
  5462 **
  5463 ** ^The sqlite3_create_module_v2() interface has a fifth parameter which
  5464 ** is a pointer to a destructor for the pClientData.  ^SQLite will
  5465 ** invoke the destructor function (if it is not NULL) when SQLite
  5466 ** no longer needs the pClientData pointer.  ^The destructor will also
  5467 ** be invoked if the call to sqlite3_create_module_v2() fails.
  5468 ** ^The sqlite3_create_module()
  5469 ** interface is equivalent to sqlite3_create_module_v2() with a NULL
  5470 ** destructor.
  5471 */
  5472 SQLITE_API int sqlite3_create_module(
  5473   sqlite3 *db,               /* SQLite connection to register module with */
  5474   const char *zName,         /* Name of the module */
  5475   const sqlite3_module *p,   /* Methods for the module */
  5476   void *pClientData          /* Client data for xCreate/xConnect */
  5477 );
  5478 SQLITE_API int sqlite3_create_module_v2(
  5479   sqlite3 *db,               /* SQLite connection to register module with */
  5480   const char *zName,         /* Name of the module */
  5481   const sqlite3_module *p,   /* Methods for the module */
  5482   void *pClientData,         /* Client data for xCreate/xConnect */
  5483   void(*xDestroy)(void*)     /* Module destructor function */
  5484 );
  5485 
  5486 /*
  5487 ** CAPI3REF: Virtual Table Instance Object
  5488 ** KEYWORDS: sqlite3_vtab
  5489 **
  5490 ** Every [virtual table module] implementation uses a subclass
  5491 ** of this object to describe a particular instance
  5492 ** of the [virtual table].  Each subclass will
  5493 ** be tailored to the specific needs of the module implementation.
  5494 ** The purpose of this superclass is to define certain fields that are
  5495 ** common to all module implementations.
  5496 **
  5497 ** ^Virtual tables methods can set an error message by assigning a
  5498 ** string obtained from [sqlite3_mprintf()] to zErrMsg.  The method should
  5499 ** take care that any prior string is freed by a call to [sqlite3_free()]
  5500 ** prior to assigning a new string to zErrMsg.  ^After the error message
  5501 ** is delivered up to the client application, the string will be automatically
  5502 ** freed by sqlite3_free() and the zErrMsg field will be zeroed.
  5503 */
  5504 struct sqlite3_vtab {
  5505   const sqlite3_module *pModule;  /* The module for this virtual table */
  5506   int nRef;                       /* NO LONGER USED */
  5507   char *zErrMsg;                  /* Error message from sqlite3_mprintf() */
  5508   /* Virtual table implementations will typically add additional fields */
  5509 };
  5510 
  5511 /*
  5512 ** CAPI3REF: Virtual Table Cursor Object
  5513 ** KEYWORDS: sqlite3_vtab_cursor {virtual table cursor}
  5514 **
  5515 ** Every [virtual table module] implementation uses a subclass of the
  5516 ** following structure to describe cursors that point into the
  5517 ** [virtual table] and are used
  5518 ** to loop through the virtual table.  Cursors are created using the
  5519 ** [sqlite3_module.xOpen | xOpen] method of the module and are destroyed
  5520 ** by the [sqlite3_module.xClose | xClose] method.  Cursors are used
  5521 ** by the [xFilter], [xNext], [xEof], [xColumn], and [xRowid] methods
  5522 ** of the module.  Each module implementation will define
  5523 ** the content of a cursor structure to suit its own needs.
  5524 **
  5525 ** This superclass exists in order to define fields of the cursor that
  5526 ** are common to all implementations.
  5527 */
  5528 struct sqlite3_vtab_cursor {
  5529   sqlite3_vtab *pVtab;      /* Virtual table of this cursor */
  5530   /* Virtual table implementations will typically add additional fields */
  5531 };
  5532 
  5533 /*
  5534 ** CAPI3REF: Declare The Schema Of A Virtual Table
  5535 **
  5536 ** ^The [xCreate] and [xConnect] methods of a
  5537 ** [virtual table module] call this interface
  5538 ** to declare the format (the names and datatypes of the columns) of
  5539 ** the virtual tables they implement.
  5540 */
  5541 SQLITE_API int sqlite3_declare_vtab(sqlite3*, const char *zSQL);
  5542 
  5543 /*
  5544 ** CAPI3REF: Overload A Function For A Virtual Table
  5545 **
  5546 ** ^(Virtual tables can provide alternative implementations of functions
  5547 ** using the [xFindFunction] method of the [virtual table module].  
  5548 ** But global versions of those functions
  5549 ** must exist in order to be overloaded.)^
  5550 **
  5551 ** ^(This API makes sure a global version of a function with a particular
  5552 ** name and number of parameters exists.  If no such function exists
  5553 ** before this API is called, a new function is created.)^  ^The implementation
  5554 ** of the new function always causes an exception to be thrown.  So
  5555 ** the new function is not good for anything by itself.  Its only
  5556 ** purpose is to be a placeholder function that can be overloaded
  5557 ** by a [virtual table].
  5558 */
  5559 SQLITE_API int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);
  5560 
  5561 /*
  5562 ** The interface to the virtual-table mechanism defined above (back up
  5563 ** to a comment remarkably similar to this one) is currently considered
  5564 ** to be experimental.  The interface might change in incompatible ways.
  5565 ** If this is a problem for you, do not use the interface at this time.
  5566 **
  5567 ** When the virtual-table mechanism stabilizes, we will declare the
  5568 ** interface fixed, support it indefinitely, and remove this comment.
  5569 */
  5570 
  5571 /*
  5572 ** CAPI3REF: A Handle To An Open BLOB
  5573 ** KEYWORDS: {BLOB handle} {BLOB handles}
  5574 **
  5575 ** An instance of this object represents an open BLOB on which
  5576 ** [sqlite3_blob_open | incremental BLOB I/O] can be performed.
  5577 ** ^Objects of this type are created by [sqlite3_blob_open()]
  5578 ** and destroyed by [sqlite3_blob_close()].
  5579 ** ^The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces
  5580 ** can be used to read or write small subsections of the BLOB.
  5581 ** ^The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes.
  5582 */
  5583 typedef struct sqlite3_blob sqlite3_blob;
  5584 
  5585 /*
  5586 ** CAPI3REF: Open A BLOB For Incremental I/O
  5587 **
  5588 ** ^(This interfaces opens a [BLOB handle | handle] to the BLOB located
  5589 ** in row iRow, column zColumn, table zTable in database zDb;
  5590 ** in other words, the same BLOB that would be selected by:
  5591 **
  5592 ** <pre>
  5593 **     SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow;
  5594 ** </pre>)^
  5595 **
  5596 ** ^If the flags parameter is non-zero, then the BLOB is opened for read
  5597 ** and write access. ^If it is zero, the BLOB is opened for read access.
  5598 ** ^It is not possible to open a column that is part of an index or primary 
  5599 ** key for writing. ^If [foreign key constraints] are enabled, it is 
  5600 ** not possible to open a column that is part of a [child key] for writing.
  5601 **
  5602 ** ^Note that the database name is not the filename that contains
  5603 ** the database but rather the symbolic name of the database that
  5604 ** appears after the AS keyword when the database is connected using [ATTACH].
  5605 ** ^For the main database file, the database name is "main".
  5606 ** ^For TEMP tables, the database name is "temp".
  5607 **
  5608 ** ^(On success, [SQLITE_OK] is returned and the new [BLOB handle] is written
  5609 ** to *ppBlob. Otherwise an [error code] is returned and *ppBlob is set
  5610 ** to be a null pointer.)^
  5611 ** ^This function sets the [database connection] error code and message
  5612 ** accessible via [sqlite3_errcode()] and [sqlite3_errmsg()] and related
  5613 ** functions. ^Note that the *ppBlob variable is always initialized in a
  5614 ** way that makes it safe to invoke [sqlite3_blob_close()] on *ppBlob
  5615 ** regardless of the success or failure of this routine.
  5616 **
  5617 ** ^(If the row that a BLOB handle points to is modified by an
  5618 ** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
  5619 ** then the BLOB handle is marked as "expired".
  5620 ** This is true if any column of the row is changed, even a column
  5621 ** other than the one the BLOB handle is open on.)^
  5622 ** ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
  5623 ** an expired BLOB handle fail with a return code of [SQLITE_ABORT].
  5624 ** ^(Changes written into a BLOB prior to the BLOB expiring are not
  5625 ** rolled back by the expiration of the BLOB.  Such changes will eventually
  5626 ** commit if the transaction continues to completion.)^
  5627 **
  5628 ** ^Use the [sqlite3_blob_bytes()] interface to determine the size of
  5629 ** the opened blob.  ^The size of a blob may not be changed by this
  5630 ** interface.  Use the [UPDATE] SQL command to change the size of a
  5631 ** blob.
  5632 **
  5633 ** ^The [sqlite3_blob_open()] interface will fail for a [WITHOUT ROWID]
  5634 ** table.  Incremental BLOB I/O is not possible on [WITHOUT ROWID] tables.
  5635 **
  5636 ** ^The [sqlite3_bind_zeroblob()] and [sqlite3_result_zeroblob()] interfaces
  5637 ** and the built-in [zeroblob] SQL function can be used, if desired,
  5638 ** to create an empty, zero-filled blob in which to read or write using
  5639 ** this interface.
  5640 **
  5641 ** To avoid a resource leak, every open [BLOB handle] should eventually
  5642 ** be released by a call to [sqlite3_blob_close()].
  5643 */
  5644 SQLITE_API int sqlite3_blob_open(
  5645   sqlite3*,
  5646   const char *zDb,
  5647   const char *zTable,
  5648   const char *zColumn,
  5649   sqlite3_int64 iRow,
  5650   int flags,
  5651   sqlite3_blob **ppBlob
  5652 );
  5653 
  5654 /*
  5655 ** CAPI3REF: Move a BLOB Handle to a New Row
  5656 **
  5657 ** ^This function is used to move an existing blob handle so that it points
  5658 ** to a different row of the same database table. ^The new row is identified
  5659 ** by the rowid value passed as the second argument. Only the row can be
  5660 ** changed. ^The database, table and column on which the blob handle is open
  5661 ** remain the same. Moving an existing blob handle to a new row can be
  5662 ** faster than closing the existing handle and opening a new one.
  5663 **
  5664 ** ^(The new row must meet the same criteria as for [sqlite3_blob_open()] -
  5665 ** it must exist and there must be either a blob or text value stored in
  5666 ** the nominated column.)^ ^If the new row is not present in the table, or if
  5667 ** it does not contain a blob or text value, or if another error occurs, an
  5668 ** SQLite error code is returned and the blob handle is considered aborted.
  5669 ** ^All subsequent calls to [sqlite3_blob_read()], [sqlite3_blob_write()] or
  5670 ** [sqlite3_blob_reopen()] on an aborted blob handle immediately return
  5671 ** SQLITE_ABORT. ^Calling [sqlite3_blob_bytes()] on an aborted blob handle
  5672 ** always returns zero.
  5673 **
  5674 ** ^This function sets the database handle error code and message.
  5675 */
  5676 SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_blob_reopen(sqlite3_blob *, sqlite3_int64);
  5677 
  5678 /*
  5679 ** CAPI3REF: Close A BLOB Handle
  5680 **
  5681 ** ^Closes an open [BLOB handle].
  5682 **
  5683 ** ^Closing a BLOB shall cause the current transaction to commit
  5684 ** if there are no other BLOBs, no pending prepared statements, and the
  5685 ** database connection is in [autocommit mode].
  5686 ** ^If any writes were made to the BLOB, they might be held in cache
  5687 ** until the close operation if they will fit.
  5688 **
  5689 ** ^(Closing the BLOB often forces the changes
  5690 ** out to disk and so if any I/O errors occur, they will likely occur
  5691 ** at the time when the BLOB is closed.  Any errors that occur during
  5692 ** closing are reported as a non-zero return value.)^
  5693 **
  5694 ** ^(The BLOB is closed unconditionally.  Even if this routine returns
  5695 ** an error code, the BLOB is still closed.)^
  5696 **
  5697 ** ^Calling this routine with a null pointer (such as would be returned
  5698 ** by a failed call to [sqlite3_blob_open()]) is a harmless no-op.
  5699 */
  5700 SQLITE_API int sqlite3_blob_close(sqlite3_blob *);
  5701 
  5702 /*
  5703 ** CAPI3REF: Return The Size Of An Open BLOB
  5704 **
  5705 ** ^Returns the size in bytes of the BLOB accessible via the 
  5706 ** successfully opened [BLOB handle] in its only argument.  ^The
  5707 ** incremental blob I/O routines can only read or overwriting existing
  5708 ** blob content; they cannot change the size of a blob.
  5709 **
  5710 ** This routine only works on a [BLOB handle] which has been created
  5711 ** by a prior successful call to [sqlite3_blob_open()] and which has not
  5712 ** been closed by [sqlite3_blob_close()].  Passing any other pointer in
  5713 ** to this routine results in undefined and probably undesirable behavior.
  5714 */
  5715 SQLITE_API int sqlite3_blob_bytes(sqlite3_blob *);
  5716 
  5717 /*
  5718 ** CAPI3REF: Read Data From A BLOB Incrementally
  5719 **
  5720 ** ^(This function is used to read data from an open [BLOB handle] into a
  5721 ** caller-supplied buffer. N bytes of data are copied into buffer Z
  5722 ** from the open BLOB, starting at offset iOffset.)^
  5723 **
  5724 ** ^If offset iOffset is less than N bytes from the end of the BLOB,
  5725 ** [SQLITE_ERROR] is returned and no data is read.  ^If N or iOffset is
  5726 ** less than zero, [SQLITE_ERROR] is returned and no data is read.
  5727 ** ^The size of the blob (and hence the maximum value of N+iOffset)
  5728 ** can be determined using the [sqlite3_blob_bytes()] interface.
  5729 **
  5730 ** ^An attempt to read from an expired [BLOB handle] fails with an
  5731 ** error code of [SQLITE_ABORT].
  5732 **
  5733 ** ^(On success, sqlite3_blob_read() returns SQLITE_OK.
  5734 ** Otherwise, an [error code] or an [extended error code] is returned.)^
  5735 **
  5736 ** This routine only works on a [BLOB handle] which has been created
  5737 ** by a prior successful call to [sqlite3_blob_open()] and which has not
  5738 ** been closed by [sqlite3_blob_close()].  Passing any other pointer in
  5739 ** to this routine results in undefined and probably undesirable behavior.
  5740 **
  5741 ** See also: [sqlite3_blob_write()].
  5742 */
  5743 SQLITE_API int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);
  5744 
  5745 /*
  5746 ** CAPI3REF: Write Data Into A BLOB Incrementally
  5747 **
  5748 ** ^This function is used to write data into an open [BLOB handle] from a
  5749 ** caller-supplied buffer. ^N bytes of data are copied from the buffer Z
  5750 ** into the open BLOB, starting at offset iOffset.
  5751 **
  5752 ** ^If the [BLOB handle] passed as the first argument was not opened for
  5753 ** writing (the flags parameter to [sqlite3_blob_open()] was zero),
  5754 ** this function returns [SQLITE_READONLY].
  5755 **
  5756 ** ^This function may only modify the contents of the BLOB; it is
  5757 ** not possible to increase the size of a BLOB using this API.
  5758 ** ^If offset iOffset is less than N bytes from the end of the BLOB,
  5759 ** [SQLITE_ERROR] is returned and no data is written.  ^If N is
  5760 ** less than zero [SQLITE_ERROR] is returned and no data is written.
  5761 ** The size of the BLOB (and hence the maximum value of N+iOffset)
  5762 ** can be determined using the [sqlite3_blob_bytes()] interface.
  5763 **
  5764 ** ^An attempt to write to an expired [BLOB handle] fails with an
  5765 ** error code of [SQLITE_ABORT].  ^Writes to the BLOB that occurred
  5766 ** before the [BLOB handle] expired are not rolled back by the
  5767 ** expiration of the handle, though of course those changes might
  5768 ** have been overwritten by the statement that expired the BLOB handle
  5769 ** or by other independent statements.
  5770 **
  5771 ** ^(On success, sqlite3_blob_write() returns SQLITE_OK.
  5772 ** Otherwise, an  [error code] or an [extended error code] is returned.)^
  5773 **
  5774 ** This routine only works on a [BLOB handle] which has been created
  5775 ** by a prior successful call to [sqlite3_blob_open()] and which has not
  5776 ** been closed by [sqlite3_blob_close()].  Passing any other pointer in
  5777 ** to this routine results in undefined and probably undesirable behavior.
  5778 **
  5779 ** See also: [sqlite3_blob_read()].
  5780 */
  5781 SQLITE_API int sqlite3_blob_write(sqlite3_blob *, const void *z, int n, int iOffset);
  5782 
  5783 /*
  5784 ** CAPI3REF: Virtual File System Objects
  5785 **
  5786 ** A virtual filesystem (VFS) is an [sqlite3_vfs] object
  5787 ** that SQLite uses to interact
  5788 ** with the underlying operating system.  Most SQLite builds come with a
  5789 ** single default VFS that is appropriate for the host computer.
  5790 ** New VFSes can be registered and existing VFSes can be unregistered.
  5791 ** The following interfaces are provided.
  5792 **
  5793 ** ^The sqlite3_vfs_find() interface returns a pointer to a VFS given its name.
  5794 ** ^Names are case sensitive.
  5795 ** ^Names are zero-terminated UTF-8 strings.
  5796 ** ^If there is no match, a NULL pointer is returned.
  5797 ** ^If zVfsName is NULL then the default VFS is returned.
  5798 **
  5799 ** ^New VFSes are registered with sqlite3_vfs_register().
  5800 ** ^Each new VFS becomes the default VFS if the makeDflt flag is set.
  5801 ** ^The same VFS can be registered multiple times without injury.
  5802 ** ^To make an existing VFS into the default VFS, register it again
  5803 ** with the makeDflt flag set.  If two different VFSes with the
  5804 ** same name are registered, the behavior is undefined.  If a
  5805 ** VFS is registered with a name that is NULL or an empty string,
  5806 ** then the behavior is undefined.
  5807 **
  5808 ** ^Unregister a VFS with the sqlite3_vfs_unregister() interface.
  5809 ** ^(If the default VFS is unregistered, another VFS is chosen as
  5810 ** the default.  The choice for the new VFS is arbitrary.)^
  5811 */
  5812 SQLITE_API sqlite3_vfs *sqlite3_vfs_find(const char *zVfsName);
  5813 SQLITE_API int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt);
  5814 SQLITE_API int sqlite3_vfs_unregister(sqlite3_vfs*);
  5815 
  5816 /*
  5817 ** CAPI3REF: Mutexes
  5818 **
  5819 ** The SQLite core uses these routines for thread
  5820 ** synchronization. Though they are intended for internal
  5821 ** use by SQLite, code that links against SQLite is
  5822 ** permitted to use any of these routines.
  5823 **
  5824 ** The SQLite source code contains multiple implementations
  5825 ** of these mutex routines.  An appropriate implementation
  5826 ** is selected automatically at compile-time.  ^(The following
  5827 ** implementations are available in the SQLite core:
  5828 **
  5829 ** <ul>
  5830 ** <li>   SQLITE_MUTEX_PTHREADS
  5831 ** <li>   SQLITE_MUTEX_W32
  5832 ** <li>   SQLITE_MUTEX_NOOP
  5833 ** </ul>)^
  5834 **
  5835 ** ^The SQLITE_MUTEX_NOOP implementation is a set of routines
  5836 ** that does no real locking and is appropriate for use in
  5837 ** a single-threaded application.  ^The SQLITE_MUTEX_PTHREADS and
  5838 ** SQLITE_MUTEX_W32 implementations are appropriate for use on Unix
  5839 ** and Windows.
  5840 **
  5841 ** ^(If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor
  5842 ** macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex
  5843 ** implementation is included with the library. In this case the
  5844 ** application must supply a custom mutex implementation using the
  5845 ** [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function
  5846 ** before calling sqlite3_initialize() or any other public sqlite3_
  5847 ** function that calls sqlite3_initialize().)^
  5848 **
  5849 ** ^The sqlite3_mutex_alloc() routine allocates a new
  5850 ** mutex and returns a pointer to it. ^If it returns NULL
  5851 ** that means that a mutex could not be allocated.  ^SQLite
  5852 ** will unwind its stack and return an error.  ^(The argument
  5853 ** to sqlite3_mutex_alloc() is one of these integer constants:
  5854 **
  5855 ** <ul>
  5856 ** <li>  SQLITE_MUTEX_FAST
  5857 ** <li>  SQLITE_MUTEX_RECURSIVE
  5858 ** <li>  SQLITE_MUTEX_STATIC_MASTER
  5859 ** <li>  SQLITE_MUTEX_STATIC_MEM
  5860 ** <li>  SQLITE_MUTEX_STATIC_OPEN
  5861 ** <li>  SQLITE_MUTEX_STATIC_PRNG
  5862 ** <li>  SQLITE_MUTEX_STATIC_LRU
  5863 ** <li>  SQLITE_MUTEX_STATIC_PMEM
  5864 ** <li>  SQLITE_MUTEX_STATIC_APP1
  5865 ** <li>  SQLITE_MUTEX_STATIC_APP2
  5866 ** </ul>)^
  5867 **
  5868 ** ^The first two constants (SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE)
  5869 ** cause sqlite3_mutex_alloc() to create
  5870 ** a new mutex.  ^The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
  5871 ** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
  5872 ** The mutex implementation does not need to make a distinction
  5873 ** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
  5874 ** not want to.  ^SQLite will only request a recursive mutex in
  5875 ** cases where it really needs one.  ^If a faster non-recursive mutex
  5876 ** implementation is available on the host platform, the mutex subsystem
  5877 ** might return such a mutex in response to SQLITE_MUTEX_FAST.
  5878 **
  5879 ** ^The other allowed parameters to sqlite3_mutex_alloc() (anything other
  5880 ** than SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE) each return
  5881 ** a pointer to a static preexisting mutex.  ^Six static mutexes are
  5882 ** used by the current version of SQLite.  Future versions of SQLite
  5883 ** may add additional static mutexes.  Static mutexes are for internal
  5884 ** use by SQLite only.  Applications that use SQLite mutexes should
  5885 ** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
  5886 ** SQLITE_MUTEX_RECURSIVE.
  5887 **
  5888 ** ^Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
  5889 ** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
  5890 ** returns a different mutex on every call.  ^But for the static
  5891 ** mutex types, the same mutex is returned on every call that has
  5892 ** the same type number.
  5893 **
  5894 ** ^The sqlite3_mutex_free() routine deallocates a previously
  5895 ** allocated dynamic mutex.  ^SQLite is careful to deallocate every
  5896 ** dynamic mutex that it allocates.  The dynamic mutexes must not be in
  5897 ** use when they are deallocated.  Attempting to deallocate a static
  5898 ** mutex results in undefined behavior.  ^SQLite never deallocates
  5899 ** a static mutex.
  5900 **
  5901 ** ^The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
  5902 ** to enter a mutex.  ^If another thread is already within the mutex,
  5903 ** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
  5904 ** SQLITE_BUSY.  ^The sqlite3_mutex_try() interface returns [SQLITE_OK]
  5905 ** upon successful entry.  ^(Mutexes created using
  5906 ** SQLITE_MUTEX_RECURSIVE can be entered multiple times by the same thread.
  5907 ** In such cases the,
  5908 ** mutex must be exited an equal number of times before another thread
  5909 ** can enter.)^  ^(If the same thread tries to enter any other
  5910 ** kind of mutex more than once, the behavior is undefined.
  5911 ** SQLite will never exhibit
  5912 ** such behavior in its own use of mutexes.)^
  5913 **
  5914 ** ^(Some systems (for example, Windows 95) do not support the operation
  5915 ** implemented by sqlite3_mutex_try().  On those systems, sqlite3_mutex_try()
  5916 ** will always return SQLITE_BUSY.  The SQLite core only ever uses
  5917 ** sqlite3_mutex_try() as an optimization so this is acceptable behavior.)^
  5918 **
  5919 ** ^The sqlite3_mutex_leave() routine exits a mutex that was
  5920 ** previously entered by the same thread.   ^(The behavior
  5921 ** is undefined if the mutex is not currently entered by the
  5922 ** calling thread or is not currently allocated.  SQLite will
  5923 ** never do either.)^
  5924 **
  5925 ** ^If the argument to sqlite3_mutex_enter(), sqlite3_mutex_try(), or
  5926 ** sqlite3_mutex_leave() is a NULL pointer, then all three routines
  5927 ** behave as no-ops.
  5928 **
  5929 ** See also: [sqlite3_mutex_held()] and [sqlite3_mutex_notheld()].
  5930 */
  5931 SQLITE_API sqlite3_mutex *sqlite3_mutex_alloc(int);
  5932 SQLITE_API void sqlite3_mutex_free(sqlite3_mutex*);
  5933 SQLITE_API void sqlite3_mutex_enter(sqlite3_mutex*);
  5934 SQLITE_API int sqlite3_mutex_try(sqlite3_mutex*);
  5935 SQLITE_API void sqlite3_mutex_leave(sqlite3_mutex*);
  5936 
  5937 /*
  5938 ** CAPI3REF: Mutex Methods Object
  5939 **
  5940 ** An instance of this structure defines the low-level routines
  5941 ** used to allocate and use mutexes.
  5942 **
  5943 ** Usually, the default mutex implementations provided by SQLite are
  5944 ** sufficient, however the user has the option of substituting a custom
  5945 ** implementation for specialized deployments or systems for which SQLite
  5946 ** does not provide a suitable implementation. In this case, the user
  5947 ** creates and populates an instance of this structure to pass
  5948 ** to sqlite3_config() along with the [SQLITE_CONFIG_MUTEX] option.
  5949 ** Additionally, an instance of this structure can be used as an
  5950 ** output variable when querying the system for the current mutex
  5951 ** implementation, using the [SQLITE_CONFIG_GETMUTEX] option.
  5952 **
  5953 ** ^The xMutexInit method defined by this structure is invoked as
  5954 ** part of system initialization by the sqlite3_initialize() function.
  5955 ** ^The xMutexInit routine is called by SQLite exactly once for each
  5956 ** effective call to [sqlite3_initialize()].
  5957 **
  5958 ** ^The xMutexEnd method defined by this structure is invoked as
  5959 ** part of system shutdown by the sqlite3_shutdown() function. The
  5960 ** implementation of this method is expected to release all outstanding
  5961 ** resources obtained by the mutex methods implementation, especially
  5962 ** those obtained by the xMutexInit method.  ^The xMutexEnd()
  5963 ** interface is invoked exactly once for each call to [sqlite3_shutdown()].
  5964 **
  5965 ** ^(The remaining seven methods defined by this structure (xMutexAlloc,
  5966 ** xMutexFree, xMutexEnter, xMutexTry, xMutexLeave, xMutexHeld and
  5967 ** xMutexNotheld) implement the following interfaces (respectively):
  5968 **
  5969 ** <ul>
  5970 **   <li>  [sqlite3_mutex_alloc()] </li>
  5971 **   <li>  [sqlite3_mutex_free()] </li>
  5972 **   <li>  [sqlite3_mutex_enter()] </li>
  5973 **   <li>  [sqlite3_mutex_try()] </li>
  5974 **   <li>  [sqlite3_mutex_leave()] </li>
  5975 **   <li>  [sqlite3_mutex_held()] </li>
  5976 **   <li>  [sqlite3_mutex_notheld()] </li>
  5977 ** </ul>)^
  5978 **
  5979 ** The only difference is that the public sqlite3_XXX functions enumerated
  5980 ** above silently ignore any invocations that pass a NULL pointer instead
  5981 ** of a valid mutex handle. The implementations of the methods defined
  5982 ** by this structure are not required to handle this case, the results
  5983 ** of passing a NULL pointer instead of a valid mutex handle are undefined
  5984 ** (i.e. it is acceptable to provide an implementation that segfaults if
  5985 ** it is passed a NULL pointer).
  5986 **
  5987 ** The xMutexInit() method must be threadsafe.  ^It must be harmless to
  5988 ** invoke xMutexInit() multiple times within the same process and without
  5989 ** intervening calls to xMutexEnd().  Second and subsequent calls to
  5990 ** xMutexInit() must be no-ops.
  5991 **
  5992 ** ^xMutexInit() must not use SQLite memory allocation ([sqlite3_malloc()]
  5993 ** and its associates).  ^Similarly, xMutexAlloc() must not use SQLite memory
  5994 ** allocation for a static mutex.  ^However xMutexAlloc() may use SQLite
  5995 ** memory allocation for a fast or recursive mutex.
  5996 **
  5997 ** ^SQLite will invoke the xMutexEnd() method when [sqlite3_shutdown()] is
  5998 ** called, but only if the prior call to xMutexInit returned SQLITE_OK.
  5999 ** If xMutexInit fails in any way, it is expected to clean up after itself
  6000 ** prior to returning.
  6001 */
  6002 typedef struct sqlite3_mutex_methods sqlite3_mutex_methods;
  6003 struct sqlite3_mutex_methods {
  6004   int (*xMutexInit)(void);
  6005   int (*xMutexEnd)(void);
  6006   sqlite3_mutex *(*xMutexAlloc)(int);
  6007   void (*xMutexFree)(sqlite3_mutex *);
  6008   void (*xMutexEnter)(sqlite3_mutex *);
  6009   int (*xMutexTry)(sqlite3_mutex *);
  6010   void (*xMutexLeave)(sqlite3_mutex *);