src/sqlite3.c
author Edouard Tisserant
Thu, 03 Mar 2016 13:09:12 +0100
changeset 491 d32c60ada438
parent 130 507895068f83
child 716 498156bf9993
permissions -rw-r--r--
updated sqlite to latest release
     1 /******************************************************************************
     2 ** This file is an amalgamation of many separate C source files from SQLite
     3 ** version 3.11.0.  By combining all the individual C code files into this 
     4 ** single large file, the entire code can be compiled as a single translation
     5 ** unit.  This allows many compilers to do optimizations that would not be
     6 ** possible if the files were compiled separately.  Performance improvements
     7 ** of 5% or more are commonly seen when SQLite is compiled as a single
     8 ** translation unit.
     9 **
    10 ** This file is all you need to compile SQLite.  To use SQLite in other
    11 ** programs, you need this file and the "sqlite3.h" header file that defines
    12 ** the programming interface to the SQLite library.  (If you do not have 
    13 ** the "sqlite3.h" header file at hand, you will find a copy embedded within
    14 ** the text of this file.  Search for "Begin file sqlite3.h" to find the start
    15 ** of the embedded sqlite3.h header file.) Additional code files may be needed
    16 ** if you want a wrapper to interface SQLite with your choice of programming
    17 ** language. The code for the "sqlite3" command-line shell is also in a
    18 ** separate file. This file contains only code for the core SQLite library.
    19 */
    20 #define SQLITE_CORE 1
    21 #define SQLITE_AMALGAMATION 1
    22 #ifndef SQLITE_PRIVATE
    23 # define SQLITE_PRIVATE static
    24 #endif
    25 /************** Begin file sqliteInt.h ***************************************/
    26 /*
    27 ** 2001 September 15
    28 **
    29 ** The author disclaims copyright to this source code.  In place of
    30 ** a legal notice, here is a blessing:
    31 **
    32 **    May you do good and not evil.
    33 **    May you find forgiveness for yourself and forgive others.
    34 **    May you share freely, never taking more than you give.
    35 **
    36 *************************************************************************
    37 ** Internal interface definitions for SQLite.
    38 **
    39 */
    40 #ifndef _SQLITEINT_H_
    41 #define _SQLITEINT_H_
    42 
    43 /*
    44 ** Include the header file used to customize the compiler options for MSVC.
    45 ** This should be done first so that it can successfully prevent spurious
    46 ** compiler warnings due to subsequent content in this file and other files
    47 ** that are included by this file.
    48 */
    49 /************** Include msvc.h in the middle of sqliteInt.h ******************/
    50 /************** Begin file msvc.h ********************************************/
    51 /*
    52 ** 2015 January 12
    53 **
    54 ** The author disclaims copyright to this source code.  In place of
    55 ** a legal notice, here is a blessing:
    56 **
    57 **    May you do good and not evil.
    58 **    May you find forgiveness for yourself and forgive others.
    59 **    May you share freely, never taking more than you give.
    60 **
    61 ******************************************************************************
    62 **
    63 ** This file contains code that is specific to MSVC.
    64 */
    65 #ifndef _MSVC_H_
    66 #define _MSVC_H_
    67 
    68 #if defined(_MSC_VER)
    69 #pragma warning(disable : 4054)
    70 #pragma warning(disable : 4055)
    71 #pragma warning(disable : 4100)
    72 #pragma warning(disable : 4127)
    73 #pragma warning(disable : 4130)
    74 #pragma warning(disable : 4152)
    75 #pragma warning(disable : 4189)
    76 #pragma warning(disable : 4206)
    77 #pragma warning(disable : 4210)
    78 #pragma warning(disable : 4232)
    79 #pragma warning(disable : 4244)
    80 #pragma warning(disable : 4305)
    81 #pragma warning(disable : 4306)
    82 #pragma warning(disable : 4702)
    83 #pragma warning(disable : 4706)
    84 #endif /* defined(_MSC_VER) */
    85 
    86 #endif /* _MSVC_H_ */
    87 
    88 /************** End of msvc.h ************************************************/
    89 /************** Continuing where we left off in sqliteInt.h ******************/
    90 
    91 /*
    92 ** Special setup for VxWorks
    93 */
    94 /************** Include vxworks.h in the middle of sqliteInt.h ***************/
    95 /************** Begin file vxworks.h *****************************************/
    96 /*
    97 ** 2015-03-02
    98 **
    99 ** The author disclaims copyright to this source code.  In place of
   100 ** a legal notice, here is a blessing:
   101 **
   102 **    May you do good and not evil.
   103 **    May you find forgiveness for yourself and forgive others.
   104 **    May you share freely, never taking more than you give.
   105 **
   106 ******************************************************************************
   107 **
   108 ** This file contains code that is specific to Wind River's VxWorks
   109 */
   110 #if defined(__RTP__) || defined(_WRS_KERNEL)
   111 /* This is VxWorks.  Set up things specially for that OS
   112 */
   113 #include <vxWorks.h>
   114 #include <pthread.h>  /* amalgamator: dontcache */
   115 #define OS_VXWORKS 1
   116 #define SQLITE_OS_OTHER 0
   117 #define SQLITE_HOMEGROWN_RECURSIVE_MUTEX 1
   118 #define SQLITE_OMIT_LOAD_EXTENSION 1
   119 #define SQLITE_ENABLE_LOCKING_STYLE 0
   120 #define HAVE_UTIME 1
   121 #else
   122 /* This is not VxWorks. */
   123 #define OS_VXWORKS 0
   124 #define HAVE_FCHOWN 1
   125 #define HAVE_READLINK 1
   126 #define HAVE_LSTAT 1
   127 #endif /* defined(_WRS_KERNEL) */
   128 
   129 /************** End of vxworks.h *********************************************/
   130 /************** Continuing where we left off in sqliteInt.h ******************/
   131 
   132 /*
   133 ** These #defines should enable >2GB file support on POSIX if the
   134 ** underlying operating system supports it.  If the OS lacks
   135 ** large file support, or if the OS is windows, these should be no-ops.
   136 **
   137 ** Ticket #2739:  The _LARGEFILE_SOURCE macro must appear before any
   138 ** system #includes.  Hence, this block of code must be the very first
   139 ** code in all source files.
   140 **
   141 ** Large file support can be disabled using the -DSQLITE_DISABLE_LFS switch
   142 ** on the compiler command line.  This is necessary if you are compiling
   143 ** on a recent machine (ex: Red Hat 7.2) but you want your code to work
   144 ** on an older machine (ex: Red Hat 6.0).  If you compile on Red Hat 7.2
   145 ** without this option, LFS is enable.  But LFS does not exist in the kernel
   146 ** in Red Hat 6.0, so the code won't work.  Hence, for maximum binary
   147 ** portability you should omit LFS.
   148 **
   149 ** The previous paragraph was written in 2005.  (This paragraph is written
   150 ** on 2008-11-28.) These days, all Linux kernels support large files, so
   151 ** you should probably leave LFS enabled.  But some embedded platforms might
   152 ** lack LFS in which case the SQLITE_DISABLE_LFS macro might still be useful.
   153 **
   154 ** Similar is true for Mac OS X.  LFS is only supported on Mac OS X 9 and later.
   155 */
   156 #ifndef SQLITE_DISABLE_LFS
   157 # define _LARGE_FILE       1
   158 # ifndef _FILE_OFFSET_BITS
   159 #   define _FILE_OFFSET_BITS 64
   160 # endif
   161 # define _LARGEFILE_SOURCE 1
   162 #endif
   163 
   164 /* What version of GCC is being used.  0 means GCC is not being used */
   165 #ifdef __GNUC__
   166 # define GCC_VERSION (__GNUC__*1000000+__GNUC_MINOR__*1000+__GNUC_PATCHLEVEL__)
   167 #else
   168 # define GCC_VERSION 0
   169 #endif
   170 
   171 /* Needed for various definitions... */
   172 #if defined(__GNUC__) && !defined(_GNU_SOURCE)
   173 # define _GNU_SOURCE
   174 #endif
   175 
   176 #if defined(__OpenBSD__) && !defined(_BSD_SOURCE)
   177 # define _BSD_SOURCE
   178 #endif
   179 
   180 /*
   181 ** For MinGW, check to see if we can include the header file containing its
   182 ** version information, among other things.  Normally, this internal MinGW
   183 ** header file would [only] be included automatically by other MinGW header
   184 ** files; however, the contained version information is now required by this
   185 ** header file to work around binary compatibility issues (see below) and
   186 ** this is the only known way to reliably obtain it.  This entire #if block
   187 ** would be completely unnecessary if there was any other way of detecting
   188 ** MinGW via their preprocessor (e.g. if they customized their GCC to define
   189 ** some MinGW-specific macros).  When compiling for MinGW, either the
   190 ** _HAVE_MINGW_H or _HAVE__MINGW_H (note the extra underscore) macro must be
   191 ** defined; otherwise, detection of conditions specific to MinGW will be
   192 ** disabled.
   193 */
   194 #if defined(_HAVE_MINGW_H)
   195 # include "mingw.h"
   196 #elif defined(_HAVE__MINGW_H)
   197 # include "_mingw.h"
   198 #endif
   199 
   200 /*
   201 ** For MinGW version 4.x (and higher), check to see if the _USE_32BIT_TIME_T
   202 ** define is required to maintain binary compatibility with the MSVC runtime
   203 ** library in use (e.g. for Windows XP).
   204 */
   205 #if !defined(_USE_32BIT_TIME_T) && !defined(_USE_64BIT_TIME_T) && \
   206     defined(_WIN32) && !defined(_WIN64) && \
   207     defined(__MINGW_MAJOR_VERSION) && __MINGW_MAJOR_VERSION >= 4 && \
   208     defined(__MSVCRT__)
   209 # define _USE_32BIT_TIME_T
   210 #endif
   211 
   212 /* The public SQLite interface.  The _FILE_OFFSET_BITS macro must appear
   213 ** first in QNX.  Also, the _USE_32BIT_TIME_T macro must appear first for
   214 ** MinGW.
   215 */
   216 /************** Include sqlite3.h in the middle of sqliteInt.h ***************/
   217 /************** Begin file sqlite3.h *****************************************/
   218 /*
   219 ** 2001 September 15
   220 **
   221 ** The author disclaims copyright to this source code.  In place of
   222 ** a legal notice, here is a blessing:
   223 **
   224 **    May you do good and not evil.
   225 **    May you find forgiveness for yourself and forgive others.
   226 **    May you share freely, never taking more than you give.
   227 **
   228 *************************************************************************
   229 ** This header file defines the interface that the SQLite library
   230 ** presents to client programs.  If a C-function, structure, datatype,
   231 ** or constant definition does not appear in this file, then it is
   232 ** not a published API of SQLite, is subject to change without
   233 ** notice, and should not be referenced by programs that use SQLite.
   234 **
   235 ** Some of the definitions that are in this file are marked as
   236 ** "experimental".  Experimental interfaces are normally new
   237 ** features recently added to SQLite.  We do not anticipate changes
   238 ** to experimental interfaces but reserve the right to make minor changes
   239 ** if experience from use "in the wild" suggest such changes are prudent.
   240 **
   241 ** The official C-language API documentation for SQLite is derived
   242 ** from comments in this file.  This file is the authoritative source
   243 ** on how SQLite interfaces are supposed to operate.
   244 **
   245 ** The name of this file under configuration management is "sqlite.h.in".
   246 ** The makefile makes some minor changes to this file (such as inserting
   247 ** the version number) and changes its name to "sqlite3.h" as
   248 ** part of the build process.
   249 */
   250 #ifndef _SQLITE3_H_
   251 #define _SQLITE3_H_
   252 #include <stdarg.h>     /* Needed for the definition of va_list */
   253 
   254 /*
   255 ** Make sure we can call this stuff from C++.
   256 */
   257 #if 0
   258 extern "C" {
   259 #endif
   260 
   261 
   262 /*
   263 ** Provide the ability to override linkage features of the interface.
   264 */
   265 #ifndef SQLITE_EXTERN
   266 # define SQLITE_EXTERN extern
   267 #endif
   268 #ifndef SQLITE_API
   269 # define SQLITE_API
   270 #endif
   271 #ifndef SQLITE_CDECL
   272 # define SQLITE_CDECL
   273 #endif
   274 #ifndef SQLITE_STDCALL
   275 # define SQLITE_STDCALL
   276 #endif
   277 
   278 /*
   279 ** These no-op macros are used in front of interfaces to mark those
   280 ** interfaces as either deprecated or experimental.  New applications
   281 ** should not use deprecated interfaces - they are supported for backwards
   282 ** compatibility only.  Application writers should be aware that
   283 ** experimental interfaces are subject to change in point releases.
   284 **
   285 ** These macros used to resolve to various kinds of compiler magic that
   286 ** would generate warning messages when they were used.  But that
   287 ** compiler magic ended up generating such a flurry of bug reports
   288 ** that we have taken it all out and gone back to using simple
   289 ** noop macros.
   290 */
   291 #define SQLITE_DEPRECATED
   292 #define SQLITE_EXPERIMENTAL
   293 
   294 /*
   295 ** Ensure these symbols were not defined by some previous header file.
   296 */
   297 #ifdef SQLITE_VERSION
   298 # undef SQLITE_VERSION
   299 #endif
   300 #ifdef SQLITE_VERSION_NUMBER
   301 # undef SQLITE_VERSION_NUMBER
   302 #endif
   303 
   304 /*
   305 ** CAPI3REF: Compile-Time Library Version Numbers
   306 **
   307 ** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header
   308 ** evaluates to a string literal that is the SQLite version in the
   309 ** format "X.Y.Z" where X is the major version number (always 3 for
   310 ** SQLite3) and Y is the minor version number and Z is the release number.)^
   311 ** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer
   312 ** with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z are the same
   313 ** numbers used in [SQLITE_VERSION].)^
   314 ** The SQLITE_VERSION_NUMBER for any given release of SQLite will also
   315 ** be larger than the release from which it is derived.  Either Y will
   316 ** be held constant and Z will be incremented or else Y will be incremented
   317 ** and Z will be reset to zero.
   318 **
   319 ** Since version 3.6.18, SQLite source code has been stored in the
   320 ** <a href="http://www.fossil-scm.org/">Fossil configuration management
   321 ** system</a>.  ^The SQLITE_SOURCE_ID macro evaluates to
   322 ** a string which identifies a particular check-in of SQLite
   323 ** within its configuration management system.  ^The SQLITE_SOURCE_ID
   324 ** string contains the date and time of the check-in (UTC) and an SHA1
   325 ** hash of the entire source tree.
   326 **
   327 ** See also: [sqlite3_libversion()],
   328 ** [sqlite3_libversion_number()], [sqlite3_sourceid()],
   329 ** [sqlite_version()] and [sqlite_source_id()].
   330 */
   331 #define SQLITE_VERSION        "3.11.0"
   332 #define SQLITE_VERSION_NUMBER 3011000
   333 #define SQLITE_SOURCE_ID      "2016-02-15 17:29:24 3d862f207e3adc00f78066799ac5a8c282430a5f"
   334 
   335 /*
   336 ** CAPI3REF: Run-Time Library Version Numbers
   337 ** KEYWORDS: sqlite3_version, sqlite3_sourceid
   338 **
   339 ** These interfaces provide the same information as the [SQLITE_VERSION],
   340 ** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
   341 ** but are associated with the library instead of the header file.  ^(Cautious
   342 ** programmers might include assert() statements in their application to
   343 ** verify that values returned by these interfaces match the macros in
   344 ** the header, and thus ensure that the application is
   345 ** compiled with matching library and header files.
   346 **
   347 ** <blockquote><pre>
   348 ** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
   349 ** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );
   350 ** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
   351 ** </pre></blockquote>)^
   352 **
   353 ** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
   354 ** macro.  ^The sqlite3_libversion() function returns a pointer to the
   355 ** to the sqlite3_version[] string constant.  The sqlite3_libversion()
   356 ** function is provided for use in DLLs since DLL users usually do not have
   357 ** direct access to string constants within the DLL.  ^The
   358 ** sqlite3_libversion_number() function returns an integer equal to
   359 ** [SQLITE_VERSION_NUMBER].  ^The sqlite3_sourceid() function returns 
   360 ** a pointer to a string constant whose value is the same as the 
   361 ** [SQLITE_SOURCE_ID] C preprocessor macro.
   362 **
   363 ** See also: [sqlite_version()] and [sqlite_source_id()].
   364 */
   365 SQLITE_API const char sqlite3_version[] = SQLITE_VERSION;
   366 SQLITE_API const char *SQLITE_STDCALL sqlite3_libversion(void);
   367 SQLITE_API const char *SQLITE_STDCALL sqlite3_sourceid(void);
   368 SQLITE_API int SQLITE_STDCALL sqlite3_libversion_number(void);
   369 
   370 /*
   371 ** CAPI3REF: Run-Time Library Compilation Options Diagnostics
   372 **
   373 ** ^The sqlite3_compileoption_used() function returns 0 or 1 
   374 ** indicating whether the specified option was defined at 
   375 ** compile time.  ^The SQLITE_ prefix may be omitted from the 
   376 ** option name passed to sqlite3_compileoption_used().  
   377 **
   378 ** ^The sqlite3_compileoption_get() function allows iterating
   379 ** over the list of options that were defined at compile time by
   380 ** returning the N-th compile time option string.  ^If N is out of range,
   381 ** sqlite3_compileoption_get() returns a NULL pointer.  ^The SQLITE_ 
   382 ** prefix is omitted from any strings returned by 
   383 ** sqlite3_compileoption_get().
   384 **
   385 ** ^Support for the diagnostic functions sqlite3_compileoption_used()
   386 ** and sqlite3_compileoption_get() may be omitted by specifying the 
   387 ** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
   388 **
   389 ** See also: SQL functions [sqlite_compileoption_used()] and
   390 ** [sqlite_compileoption_get()] and the [compile_options pragma].
   391 */
   392 #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
   393 SQLITE_API int SQLITE_STDCALL sqlite3_compileoption_used(const char *zOptName);
   394 SQLITE_API const char *SQLITE_STDCALL sqlite3_compileoption_get(int N);
   395 #endif
   396 
   397 /*
   398 ** CAPI3REF: Test To See If The Library Is Threadsafe
   399 **
   400 ** ^The sqlite3_threadsafe() function returns zero if and only if
   401 ** SQLite was compiled with mutexing code omitted due to the
   402 ** [SQLITE_THREADSAFE] compile-time option being set to 0.
   403 **
   404 ** SQLite can be compiled with or without mutexes.  When
   405 ** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes
   406 ** are enabled and SQLite is threadsafe.  When the
   407 ** [SQLITE_THREADSAFE] macro is 0, 
   408 ** the mutexes are omitted.  Without the mutexes, it is not safe
   409 ** to use SQLite concurrently from more than one thread.
   410 **
   411 ** Enabling mutexes incurs a measurable performance penalty.
   412 ** So if speed is of utmost importance, it makes sense to disable
   413 ** the mutexes.  But for maximum safety, mutexes should be enabled.
   414 ** ^The default behavior is for mutexes to be enabled.
   415 **
   416 ** This interface can be used by an application to make sure that the
   417 ** version of SQLite that it is linking against was compiled with
   418 ** the desired setting of the [SQLITE_THREADSAFE] macro.
   419 **
   420 ** This interface only reports on the compile-time mutex setting
   421 ** of the [SQLITE_THREADSAFE] flag.  If SQLite is compiled with
   422 ** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but
   423 ** can be fully or partially disabled using a call to [sqlite3_config()]
   424 ** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],
   425 ** or [SQLITE_CONFIG_SERIALIZED].  ^(The return value of the
   426 ** sqlite3_threadsafe() function shows only the compile-time setting of
   427 ** thread safety, not any run-time changes to that setting made by
   428 ** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()
   429 ** is unchanged by calls to sqlite3_config().)^
   430 **
   431 ** See the [threading mode] documentation for additional information.
   432 */
   433 SQLITE_API int SQLITE_STDCALL sqlite3_threadsafe(void);
   434 
   435 /*
   436 ** CAPI3REF: Database Connection Handle
   437 ** KEYWORDS: {database connection} {database connections}
   438 **
   439 ** Each open SQLite database is represented by a pointer to an instance of
   440 ** the opaque structure named "sqlite3".  It is useful to think of an sqlite3
   441 ** pointer as an object.  The [sqlite3_open()], [sqlite3_open16()], and
   442 ** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
   443 ** and [sqlite3_close_v2()] are its destructors.  There are many other
   444 ** interfaces (such as
   445 ** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
   446 ** [sqlite3_busy_timeout()] to name but three) that are methods on an
   447 ** sqlite3 object.
   448 */
   449 typedef struct sqlite3 sqlite3;
   450 
   451 /*
   452 ** CAPI3REF: 64-Bit Integer Types
   453 ** KEYWORDS: sqlite_int64 sqlite_uint64
   454 **
   455 ** Because there is no cross-platform way to specify 64-bit integer types
   456 ** SQLite includes typedefs for 64-bit signed and unsigned integers.
   457 **
   458 ** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
   459 ** The sqlite_int64 and sqlite_uint64 types are supported for backwards
   460 ** compatibility only.
   461 **
   462 ** ^The sqlite3_int64 and sqlite_int64 types can store integer values
   463 ** between -9223372036854775808 and +9223372036854775807 inclusive.  ^The
   464 ** sqlite3_uint64 and sqlite_uint64 types can store integer values 
   465 ** between 0 and +18446744073709551615 inclusive.
   466 */
   467 #ifdef SQLITE_INT64_TYPE
   468   typedef SQLITE_INT64_TYPE sqlite_int64;
   469   typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
   470 #elif defined(_MSC_VER) || defined(__BORLANDC__)
   471   typedef __int64 sqlite_int64;
   472   typedef unsigned __int64 sqlite_uint64;
   473 #else
   474   typedef long long int sqlite_int64;
   475   typedef unsigned long long int sqlite_uint64;
   476 #endif
   477 typedef sqlite_int64 sqlite3_int64;
   478 typedef sqlite_uint64 sqlite3_uint64;
   479 
   480 /*
   481 ** If compiling for a processor that lacks floating point support,
   482 ** substitute integer for floating-point.
   483 */
   484 #ifdef SQLITE_OMIT_FLOATING_POINT
   485 # define double sqlite3_int64
   486 #endif
   487 
   488 /*
   489 ** CAPI3REF: Closing A Database Connection
   490 ** DESTRUCTOR: sqlite3
   491 **
   492 ** ^The sqlite3_close() and sqlite3_close_v2() routines are destructors
   493 ** for the [sqlite3] object.
   494 ** ^Calls to sqlite3_close() and sqlite3_close_v2() return [SQLITE_OK] if
   495 ** the [sqlite3] object is successfully destroyed and all associated
   496 ** resources are deallocated.
   497 **
   498 ** ^If the database connection is associated with unfinalized prepared
   499 ** statements or unfinished sqlite3_backup objects then sqlite3_close()
   500 ** will leave the database connection open and return [SQLITE_BUSY].
   501 ** ^If sqlite3_close_v2() is called with unfinalized prepared statements
   502 ** and/or unfinished sqlite3_backups, then the database connection becomes
   503 ** an unusable "zombie" which will automatically be deallocated when the
   504 ** last prepared statement is finalized or the last sqlite3_backup is
   505 ** finished.  The sqlite3_close_v2() interface is intended for use with
   506 ** host languages that are garbage collected, and where the order in which
   507 ** destructors are called is arbitrary.
   508 **
   509 ** Applications should [sqlite3_finalize | finalize] all [prepared statements],
   510 ** [sqlite3_blob_close | close] all [BLOB handles], and 
   511 ** [sqlite3_backup_finish | finish] all [sqlite3_backup] objects associated
   512 ** with the [sqlite3] object prior to attempting to close the object.  ^If
   513 ** sqlite3_close_v2() is called on a [database connection] that still has
   514 ** outstanding [prepared statements], [BLOB handles], and/or
   515 ** [sqlite3_backup] objects then it returns [SQLITE_OK] and the deallocation
   516 ** of resources is deferred until all [prepared statements], [BLOB handles],
   517 ** and [sqlite3_backup] objects are also destroyed.
   518 **
   519 ** ^If an [sqlite3] object is destroyed while a transaction is open,
   520 ** the transaction is automatically rolled back.
   521 **
   522 ** The C parameter to [sqlite3_close(C)] and [sqlite3_close_v2(C)]
   523 ** must be either a NULL
   524 ** pointer or an [sqlite3] object pointer obtained
   525 ** from [sqlite3_open()], [sqlite3_open16()], or
   526 ** [sqlite3_open_v2()], and not previously closed.
   527 ** ^Calling sqlite3_close() or sqlite3_close_v2() with a NULL pointer
   528 ** argument is a harmless no-op.
   529 */
   530 SQLITE_API int SQLITE_STDCALL sqlite3_close(sqlite3*);
   531 SQLITE_API int SQLITE_STDCALL sqlite3_close_v2(sqlite3*);
   532 
   533 /*
   534 ** The type for a callback function.
   535 ** This is legacy and deprecated.  It is included for historical
   536 ** compatibility and is not documented.
   537 */
   538 typedef int (*sqlite3_callback)(void*,int,char**, char**);
   539 
   540 /*
   541 ** CAPI3REF: One-Step Query Execution Interface
   542 ** METHOD: sqlite3
   543 **
   544 ** The sqlite3_exec() interface is a convenience wrapper around
   545 ** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],
   546 ** that allows an application to run multiple statements of SQL
   547 ** without having to use a lot of C code. 
   548 **
   549 ** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
   550 ** semicolon-separate SQL statements passed into its 2nd argument,
   551 ** in the context of the [database connection] passed in as its 1st
   552 ** argument.  ^If the callback function of the 3rd argument to
   553 ** sqlite3_exec() is not NULL, then it is invoked for each result row
   554 ** coming out of the evaluated SQL statements.  ^The 4th argument to
   555 ** sqlite3_exec() is relayed through to the 1st argument of each
   556 ** callback invocation.  ^If the callback pointer to sqlite3_exec()
   557 ** is NULL, then no callback is ever invoked and result rows are
   558 ** ignored.
   559 **
   560 ** ^If an error occurs while evaluating the SQL statements passed into
   561 ** sqlite3_exec(), then execution of the current statement stops and
   562 ** subsequent statements are skipped.  ^If the 5th parameter to sqlite3_exec()
   563 ** is not NULL then any error message is written into memory obtained
   564 ** from [sqlite3_malloc()] and passed back through the 5th parameter.
   565 ** To avoid memory leaks, the application should invoke [sqlite3_free()]
   566 ** on error message strings returned through the 5th parameter of
   567 ** sqlite3_exec() after the error message string is no longer needed.
   568 ** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
   569 ** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
   570 ** NULL before returning.
   571 **
   572 ** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()
   573 ** routine returns SQLITE_ABORT without invoking the callback again and
   574 ** without running any subsequent SQL statements.
   575 **
   576 ** ^The 2nd argument to the sqlite3_exec() callback function is the
   577 ** number of columns in the result.  ^The 3rd argument to the sqlite3_exec()
   578 ** callback is an array of pointers to strings obtained as if from
   579 ** [sqlite3_column_text()], one for each column.  ^If an element of a
   580 ** result row is NULL then the corresponding string pointer for the
   581 ** sqlite3_exec() callback is a NULL pointer.  ^The 4th argument to the
   582 ** sqlite3_exec() callback is an array of pointers to strings where each
   583 ** entry represents the name of corresponding result column as obtained
   584 ** from [sqlite3_column_name()].
   585 **
   586 ** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer
   587 ** to an empty string, or a pointer that contains only whitespace and/or 
   588 ** SQL comments, then no SQL statements are evaluated and the database
   589 ** is not changed.
   590 **
   591 ** Restrictions:
   592 **
   593 ** <ul>
   594 ** <li> The application must ensure that the 1st parameter to sqlite3_exec()
   595 **      is a valid and open [database connection].
   596 ** <li> The application must not close the [database connection] specified by
   597 **      the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
   598 ** <li> The application must not modify the SQL statement text passed into
   599 **      the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.
   600 ** </ul>
   601 */
   602 SQLITE_API int SQLITE_STDCALL sqlite3_exec(
   603   sqlite3*,                                  /* An open database */
   604   const char *sql,                           /* SQL to be evaluated */
   605   int (*callback)(void*,int,char**,char**),  /* Callback function */
   606   void *,                                    /* 1st argument to callback */
   607   char **errmsg                              /* Error msg written here */
   608 );
   609 
   610 /*
   611 ** CAPI3REF: Result Codes
   612 ** KEYWORDS: {result code definitions}
   613 **
   614 ** Many SQLite functions return an integer result code from the set shown
   615 ** here in order to indicate success or failure.
   616 **
   617 ** New error codes may be added in future versions of SQLite.
   618 **
   619 ** See also: [extended result code definitions]
   620 */
   621 #define SQLITE_OK           0   /* Successful result */
   622 /* beginning-of-error-codes */
   623 #define SQLITE_ERROR        1   /* SQL error or missing database */
   624 #define SQLITE_INTERNAL     2   /* Internal logic error in SQLite */
   625 #define SQLITE_PERM         3   /* Access permission denied */
   626 #define SQLITE_ABORT        4   /* Callback routine requested an abort */
   627 #define SQLITE_BUSY         5   /* The database file is locked */
   628 #define SQLITE_LOCKED       6   /* A table in the database is locked */
   629 #define SQLITE_NOMEM        7   /* A malloc() failed */
   630 #define SQLITE_READONLY     8   /* Attempt to write a readonly database */
   631 #define SQLITE_INTERRUPT    9   /* Operation terminated by sqlite3_interrupt()*/
   632 #define SQLITE_IOERR       10   /* Some kind of disk I/O error occurred */
   633 #define SQLITE_CORRUPT     11   /* The database disk image is malformed */
   634 #define SQLITE_NOTFOUND    12   /* Unknown opcode in sqlite3_file_control() */
   635 #define SQLITE_FULL        13   /* Insertion failed because database is full */
   636 #define SQLITE_CANTOPEN    14   /* Unable to open the database file */
   637 #define SQLITE_PROTOCOL    15   /* Database lock protocol error */
   638 #define SQLITE_EMPTY       16   /* Database is empty */
   639 #define SQLITE_SCHEMA      17   /* The database schema changed */
   640 #define SQLITE_TOOBIG      18   /* String or BLOB exceeds size limit */
   641 #define SQLITE_CONSTRAINT  19   /* Abort due to constraint violation */
   642 #define SQLITE_MISMATCH    20   /* Data type mismatch */
   643 #define SQLITE_MISUSE      21   /* Library used incorrectly */
   644 #define SQLITE_NOLFS       22   /* Uses OS features not supported on host */
   645 #define SQLITE_AUTH        23   /* Authorization denied */
   646 #define SQLITE_FORMAT      24   /* Auxiliary database format error */
   647 #define SQLITE_RANGE       25   /* 2nd parameter to sqlite3_bind out of range */
   648 #define SQLITE_NOTADB      26   /* File opened that is not a database file */
   649 #define SQLITE_NOTICE      27   /* Notifications from sqlite3_log() */
   650 #define SQLITE_WARNING     28   /* Warnings from sqlite3_log() */
   651 #define SQLITE_ROW         100  /* sqlite3_step() has another row ready */
   652 #define SQLITE_DONE        101  /* sqlite3_step() has finished executing */
   653 /* end-of-error-codes */
   654 
   655 /*
   656 ** CAPI3REF: Extended Result Codes
   657 ** KEYWORDS: {extended result code definitions}
   658 **
   659 ** In its default configuration, SQLite API routines return one of 30 integer
   660 ** [result codes].  However, experience has shown that many of
   661 ** these result codes are too coarse-grained.  They do not provide as
   662 ** much information about problems as programmers might like.  In an effort to
   663 ** address this, newer versions of SQLite (version 3.3.8 and later) include
   664 ** support for additional result codes that provide more detailed information
   665 ** about errors. These [extended result codes] are enabled or disabled
   666 ** on a per database connection basis using the
   667 ** [sqlite3_extended_result_codes()] API.  Or, the extended code for
   668 ** the most recent error can be obtained using
   669 ** [sqlite3_extended_errcode()].
   670 */
   671 #define SQLITE_IOERR_READ              (SQLITE_IOERR | (1<<8))
   672 #define SQLITE_IOERR_SHORT_READ        (SQLITE_IOERR | (2<<8))
   673 #define SQLITE_IOERR_WRITE             (SQLITE_IOERR | (3<<8))
   674 #define SQLITE_IOERR_FSYNC             (SQLITE_IOERR | (4<<8))
   675 #define SQLITE_IOERR_DIR_FSYNC         (SQLITE_IOERR | (5<<8))
   676 #define SQLITE_IOERR_TRUNCATE          (SQLITE_IOERR | (6<<8))
   677 #define SQLITE_IOERR_FSTAT             (SQLITE_IOERR | (7<<8))
   678 #define SQLITE_IOERR_UNLOCK            (SQLITE_IOERR | (8<<8))
   679 #define SQLITE_IOERR_RDLOCK            (SQLITE_IOERR | (9<<8))
   680 #define SQLITE_IOERR_DELETE            (SQLITE_IOERR | (10<<8))
   681 #define SQLITE_IOERR_BLOCKED           (SQLITE_IOERR | (11<<8))
   682 #define SQLITE_IOERR_NOMEM             (SQLITE_IOERR | (12<<8))
   683 #define SQLITE_IOERR_ACCESS            (SQLITE_IOERR | (13<<8))
   684 #define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
   685 #define SQLITE_IOERR_LOCK              (SQLITE_IOERR | (15<<8))
   686 #define SQLITE_IOERR_CLOSE             (SQLITE_IOERR | (16<<8))
   687 #define SQLITE_IOERR_DIR_CLOSE         (SQLITE_IOERR | (17<<8))
   688 #define SQLITE_IOERR_SHMOPEN           (SQLITE_IOERR | (18<<8))
   689 #define SQLITE_IOERR_SHMSIZE           (SQLITE_IOERR | (19<<8))
   690 #define SQLITE_IOERR_SHMLOCK           (SQLITE_IOERR | (20<<8))
   691 #define SQLITE_IOERR_SHMMAP            (SQLITE_IOERR | (21<<8))
   692 #define SQLITE_IOERR_SEEK              (SQLITE_IOERR | (22<<8))
   693 #define SQLITE_IOERR_DELETE_NOENT      (SQLITE_IOERR | (23<<8))
   694 #define SQLITE_IOERR_MMAP              (SQLITE_IOERR | (24<<8))
   695 #define SQLITE_IOERR_GETTEMPPATH       (SQLITE_IOERR | (25<<8))
   696 #define SQLITE_IOERR_CONVPATH          (SQLITE_IOERR | (26<<8))
   697 #define SQLITE_IOERR_VNODE             (SQLITE_IOERR | (27<<8))
   698 #define SQLITE_IOERR_AUTH              (SQLITE_IOERR | (28<<8))
   699 #define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
   700 #define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
   701 #define SQLITE_BUSY_SNAPSHOT           (SQLITE_BUSY   |  (2<<8))
   702 #define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
   703 #define SQLITE_CANTOPEN_ISDIR          (SQLITE_CANTOPEN | (2<<8))
   704 #define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
   705 #define SQLITE_CANTOPEN_CONVPATH       (SQLITE_CANTOPEN | (4<<8))
   706 #define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
   707 #define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
   708 #define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))
   709 #define SQLITE_READONLY_ROLLBACK       (SQLITE_READONLY | (3<<8))
   710 #define SQLITE_READONLY_DBMOVED        (SQLITE_READONLY | (4<<8))
   711 #define SQLITE_ABORT_ROLLBACK          (SQLITE_ABORT | (2<<8))
   712 #define SQLITE_CONSTRAINT_CHECK        (SQLITE_CONSTRAINT | (1<<8))
   713 #define SQLITE_CONSTRAINT_COMMITHOOK   (SQLITE_CONSTRAINT | (2<<8))
   714 #define SQLITE_CONSTRAINT_FOREIGNKEY   (SQLITE_CONSTRAINT | (3<<8))
   715 #define SQLITE_CONSTRAINT_FUNCTION     (SQLITE_CONSTRAINT | (4<<8))
   716 #define SQLITE_CONSTRAINT_NOTNULL      (SQLITE_CONSTRAINT | (5<<8))
   717 #define SQLITE_CONSTRAINT_PRIMARYKEY   (SQLITE_CONSTRAINT | (6<<8))
   718 #define SQLITE_CONSTRAINT_TRIGGER      (SQLITE_CONSTRAINT | (7<<8))
   719 #define SQLITE_CONSTRAINT_UNIQUE       (SQLITE_CONSTRAINT | (8<<8))
   720 #define SQLITE_CONSTRAINT_VTAB         (SQLITE_CONSTRAINT | (9<<8))
   721 #define SQLITE_CONSTRAINT_ROWID        (SQLITE_CONSTRAINT |(10<<8))
   722 #define SQLITE_NOTICE_RECOVER_WAL      (SQLITE_NOTICE | (1<<8))
   723 #define SQLITE_NOTICE_RECOVER_ROLLBACK (SQLITE_NOTICE | (2<<8))
   724 #define SQLITE_WARNING_AUTOINDEX       (SQLITE_WARNING | (1<<8))
   725 #define SQLITE_AUTH_USER               (SQLITE_AUTH | (1<<8))
   726 
   727 /*
   728 ** CAPI3REF: Flags For File Open Operations
   729 **
   730 ** These bit values are intended for use in the
   731 ** 3rd parameter to the [sqlite3_open_v2()] interface and
   732 ** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
   733 */
   734 #define SQLITE_OPEN_READONLY         0x00000001  /* Ok for sqlite3_open_v2() */
   735 #define SQLITE_OPEN_READWRITE        0x00000002  /* Ok for sqlite3_open_v2() */
   736 #define SQLITE_OPEN_CREATE           0x00000004  /* Ok for sqlite3_open_v2() */
   737 #define SQLITE_OPEN_DELETEONCLOSE    0x00000008  /* VFS only */
   738 #define SQLITE_OPEN_EXCLUSIVE        0x00000010  /* VFS only */
   739 #define SQLITE_OPEN_AUTOPROXY        0x00000020  /* VFS only */
   740 #define SQLITE_OPEN_URI              0x00000040  /* Ok for sqlite3_open_v2() */
   741 #define SQLITE_OPEN_MEMORY           0x00000080  /* Ok for sqlite3_open_v2() */
   742 #define SQLITE_OPEN_MAIN_DB          0x00000100  /* VFS only */
   743 #define SQLITE_OPEN_TEMP_DB          0x00000200  /* VFS only */
   744 #define SQLITE_OPEN_TRANSIENT_DB     0x00000400  /* VFS only */
   745 #define SQLITE_OPEN_MAIN_JOURNAL     0x00000800  /* VFS only */
   746 #define SQLITE_OPEN_TEMP_JOURNAL     0x00001000  /* VFS only */
   747 #define SQLITE_OPEN_SUBJOURNAL       0x00002000  /* VFS only */
   748 #define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */
   749 #define SQLITE_OPEN_NOMUTEX          0x00008000  /* Ok for sqlite3_open_v2() */
   750 #define SQLITE_OPEN_FULLMUTEX        0x00010000  /* Ok for sqlite3_open_v2() */
   751 #define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
   752 #define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */
   753 #define SQLITE_OPEN_WAL              0x00080000  /* VFS only */
   754 
   755 /* Reserved:                         0x00F00000 */
   756 
   757 /*
   758 ** CAPI3REF: Device Characteristics
   759 **
   760 ** The xDeviceCharacteristics method of the [sqlite3_io_methods]
   761 ** object returns an integer which is a vector of these
   762 ** bit values expressing I/O characteristics of the mass storage
   763 ** device that holds the file that the [sqlite3_io_methods]
   764 ** refers to.
   765 **
   766 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
   767 ** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
   768 ** mean that writes of blocks that are nnn bytes in size and
   769 ** are aligned to an address which is an integer multiple of
   770 ** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
   771 ** that when data is appended to a file, the data is appended
   772 ** first then the size of the file is extended, never the other
   773 ** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
   774 ** information is written to disk in the same order as calls
   775 ** to xWrite().  The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that
   776 ** after reboot following a crash or power loss, the only bytes in a
   777 ** file that were written at the application level might have changed
   778 ** and that adjacent bytes, even bytes within the same sector are
   779 ** guaranteed to be unchanged.  The SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
   780 ** flag indicate that a file cannot be deleted when open.  The
   781 ** SQLITE_IOCAP_IMMUTABLE flag indicates that the file is on
   782 ** read-only media and cannot be changed even by processes with
   783 ** elevated privileges.
   784 */
   785 #define SQLITE_IOCAP_ATOMIC                 0x00000001
   786 #define SQLITE_IOCAP_ATOMIC512              0x00000002
   787 #define SQLITE_IOCAP_ATOMIC1K               0x00000004
   788 #define SQLITE_IOCAP_ATOMIC2K               0x00000008
   789 #define SQLITE_IOCAP_ATOMIC4K               0x00000010
   790 #define SQLITE_IOCAP_ATOMIC8K               0x00000020
   791 #define SQLITE_IOCAP_ATOMIC16K              0x00000040
   792 #define SQLITE_IOCAP_ATOMIC32K              0x00000080
   793 #define SQLITE_IOCAP_ATOMIC64K              0x00000100
   794 #define SQLITE_IOCAP_SAFE_APPEND            0x00000200
   795 #define SQLITE_IOCAP_SEQUENTIAL             0x00000400
   796 #define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN  0x00000800
   797 #define SQLITE_IOCAP_POWERSAFE_OVERWRITE    0x00001000
   798 #define SQLITE_IOCAP_IMMUTABLE              0x00002000
   799 
   800 /*
   801 ** CAPI3REF: File Locking Levels
   802 **
   803 ** SQLite uses one of these integer values as the second
   804 ** argument to calls it makes to the xLock() and xUnlock() methods
   805 ** of an [sqlite3_io_methods] object.
   806 */
   807 #define SQLITE_LOCK_NONE          0
   808 #define SQLITE_LOCK_SHARED        1
   809 #define SQLITE_LOCK_RESERVED      2
   810 #define SQLITE_LOCK_PENDING       3
   811 #define SQLITE_LOCK_EXCLUSIVE     4
   812 
   813 /*
   814 ** CAPI3REF: Synchronization Type Flags
   815 **
   816 ** When SQLite invokes the xSync() method of an
   817 ** [sqlite3_io_methods] object it uses a combination of
   818 ** these integer values as the second argument.
   819 **
   820 ** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
   821 ** sync operation only needs to flush data to mass storage.  Inode
   822 ** information need not be flushed. If the lower four bits of the flag
   823 ** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.
   824 ** If the lower four bits equal SQLITE_SYNC_FULL, that means
   825 ** to use Mac OS X style fullsync instead of fsync().
   826 **
   827 ** Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags
   828 ** with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL
   829 ** settings.  The [synchronous pragma] determines when calls to the
   830 ** xSync VFS method occur and applies uniformly across all platforms.
   831 ** The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how
   832 ** energetic or rigorous or forceful the sync operations are and
   833 ** only make a difference on Mac OSX for the default SQLite code.
   834 ** (Third-party VFS implementations might also make the distinction
   835 ** between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the
   836 ** operating systems natively supported by SQLite, only Mac OSX
   837 ** cares about the difference.)
   838 */
   839 #define SQLITE_SYNC_NORMAL        0x00002
   840 #define SQLITE_SYNC_FULL          0x00003
   841 #define SQLITE_SYNC_DATAONLY      0x00010
   842 
   843 /*
   844 ** CAPI3REF: OS Interface Open File Handle
   845 **
   846 ** An [sqlite3_file] object represents an open file in the 
   847 ** [sqlite3_vfs | OS interface layer].  Individual OS interface
   848 ** implementations will
   849 ** want to subclass this object by appending additional fields
   850 ** for their own use.  The pMethods entry is a pointer to an
   851 ** [sqlite3_io_methods] object that defines methods for performing
   852 ** I/O operations on the open file.
   853 */
   854 typedef struct sqlite3_file sqlite3_file;
   855 struct sqlite3_file {
   856   const struct sqlite3_io_methods *pMethods;  /* Methods for an open file */
   857 };
   858 
   859 /*
   860 ** CAPI3REF: OS Interface File Virtual Methods Object
   861 **
   862 ** Every file opened by the [sqlite3_vfs.xOpen] method populates an
   863 ** [sqlite3_file] object (or, more commonly, a subclass of the
   864 ** [sqlite3_file] object) with a pointer to an instance of this object.
   865 ** This object defines the methods used to perform various operations
   866 ** against the open file represented by the [sqlite3_file] object.
   867 **
   868 ** If the [sqlite3_vfs.xOpen] method sets the sqlite3_file.pMethods element 
   869 ** to a non-NULL pointer, then the sqlite3_io_methods.xClose method
   870 ** may be invoked even if the [sqlite3_vfs.xOpen] reported that it failed.  The
   871 ** only way to prevent a call to xClose following a failed [sqlite3_vfs.xOpen]
   872 ** is for the [sqlite3_vfs.xOpen] to set the sqlite3_file.pMethods element
   873 ** to NULL.
   874 **
   875 ** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
   876 ** [SQLITE_SYNC_FULL].  The first choice is the normal fsync().
   877 ** The second choice is a Mac OS X style fullsync.  The [SQLITE_SYNC_DATAONLY]
   878 ** flag may be ORed in to indicate that only the data of the file
   879 ** and not its inode needs to be synced.
   880 **
   881 ** The integer values to xLock() and xUnlock() are one of
   882 ** <ul>
   883 ** <li> [SQLITE_LOCK_NONE],
   884 ** <li> [SQLITE_LOCK_SHARED],
   885 ** <li> [SQLITE_LOCK_RESERVED],
   886 ** <li> [SQLITE_LOCK_PENDING], or
   887 ** <li> [SQLITE_LOCK_EXCLUSIVE].
   888 ** </ul>
   889 ** xLock() increases the lock. xUnlock() decreases the lock.
   890 ** The xCheckReservedLock() method checks whether any database connection,
   891 ** either in this process or in some other process, is holding a RESERVED,
   892 ** PENDING, or EXCLUSIVE lock on the file.  It returns true
   893 ** if such a lock exists and false otherwise.
   894 **
   895 ** The xFileControl() method is a generic interface that allows custom
   896 ** VFS implementations to directly control an open file using the
   897 ** [sqlite3_file_control()] interface.  The second "op" argument is an
   898 ** integer opcode.  The third argument is a generic pointer intended to
   899 ** point to a structure that may contain arguments or space in which to
   900 ** write return values.  Potential uses for xFileControl() might be
   901 ** functions to enable blocking locks with timeouts, to change the
   902 ** locking strategy (for example to use dot-file locks), to inquire
   903 ** about the status of a lock, or to break stale locks.  The SQLite
   904 ** core reserves all opcodes less than 100 for its own use.
   905 ** A [file control opcodes | list of opcodes] less than 100 is available.
   906 ** Applications that define a custom xFileControl method should use opcodes
   907 ** greater than 100 to avoid conflicts.  VFS implementations should
   908 ** return [SQLITE_NOTFOUND] for file control opcodes that they do not
   909 ** recognize.
   910 **
   911 ** The xSectorSize() method returns the sector size of the
   912 ** device that underlies the file.  The sector size is the
   913 ** minimum write that can be performed without disturbing
   914 ** other bytes in the file.  The xDeviceCharacteristics()
   915 ** method returns a bit vector describing behaviors of the
   916 ** underlying device:
   917 **
   918 ** <ul>
   919 ** <li> [SQLITE_IOCAP_ATOMIC]
   920 ** <li> [SQLITE_IOCAP_ATOMIC512]
   921 ** <li> [SQLITE_IOCAP_ATOMIC1K]
   922 ** <li> [SQLITE_IOCAP_ATOMIC2K]
   923 ** <li> [SQLITE_IOCAP_ATOMIC4K]
   924 ** <li> [SQLITE_IOCAP_ATOMIC8K]
   925 ** <li> [SQLITE_IOCAP_ATOMIC16K]
   926 ** <li> [SQLITE_IOCAP_ATOMIC32K]
   927 ** <li> [SQLITE_IOCAP_ATOMIC64K]
   928 ** <li> [SQLITE_IOCAP_SAFE_APPEND]
   929 ** <li> [SQLITE_IOCAP_SEQUENTIAL]
   930 ** </ul>
   931 **
   932 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
   933 ** any size are atomic.  The SQLITE_IOCAP_ATOMICnnn values
   934 ** mean that writes of blocks that are nnn bytes in size and
   935 ** are aligned to an address which is an integer multiple of
   936 ** nnn are atomic.  The SQLITE_IOCAP_SAFE_APPEND value means
   937 ** that when data is appended to a file, the data is appended
   938 ** first then the size of the file is extended, never the other
   939 ** way around.  The SQLITE_IOCAP_SEQUENTIAL property means that
   940 ** information is written to disk in the same order as calls
   941 ** to xWrite().
   942 **
   943 ** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
   944 ** in the unread portions of the buffer with zeros.  A VFS that
   945 ** fails to zero-fill short reads might seem to work.  However,
   946 ** failure to zero-fill short reads will eventually lead to
   947 ** database corruption.
   948 */
   949 typedef struct sqlite3_io_methods sqlite3_io_methods;
   950 struct sqlite3_io_methods {
   951   int iVersion;
   952   int (*xClose)(sqlite3_file*);
   953   int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
   954   int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
   955   int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
   956   int (*xSync)(sqlite3_file*, int flags);
   957   int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
   958   int (*xLock)(sqlite3_file*, int);
   959   int (*xUnlock)(sqlite3_file*, int);
   960   int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
   961   int (*xFileControl)(sqlite3_file*, int op, void *pArg);
   962   int (*xSectorSize)(sqlite3_file*);
   963   int (*xDeviceCharacteristics)(sqlite3_file*);
   964   /* Methods above are valid for version 1 */
   965   int (*xShmMap)(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
   966   int (*xShmLock)(sqlite3_file*, int offset, int n, int flags);
   967   void (*xShmBarrier)(sqlite3_file*);
   968   int (*xShmUnmap)(sqlite3_file*, int deleteFlag);
   969   /* Methods above are valid for version 2 */
   970   int (*xFetch)(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
   971   int (*xUnfetch)(sqlite3_file*, sqlite3_int64 iOfst, void *p);
   972   /* Methods above are valid for version 3 */
   973   /* Additional methods may be added in future releases */
   974 };
   975 
   976 /*
   977 ** CAPI3REF: Standard File Control Opcodes
   978 ** KEYWORDS: {file control opcodes} {file control opcode}
   979 **
   980 ** These integer constants are opcodes for the xFileControl method
   981 ** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
   982 ** interface.
   983 **
   984 ** <ul>
   985 ** <li>[[SQLITE_FCNTL_LOCKSTATE]]
   986 ** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging.  This
   987 ** opcode causes the xFileControl method to write the current state of
   988 ** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
   989 ** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
   990 ** into an integer that the pArg argument points to. This capability
   991 ** is used during testing and is only available when the SQLITE_TEST
   992 ** compile-time option is used.
   993 **
   994 ** <li>[[SQLITE_FCNTL_SIZE_HINT]]
   995 ** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
   996 ** layer a hint of how large the database file will grow to be during the
   997 ** current transaction.  This hint is not guaranteed to be accurate but it
   998 ** is often close.  The underlying VFS might choose to preallocate database
   999 ** file space based on this hint in order to help writes to the database
  1000 ** file run faster.
  1001 **
  1002 ** <li>[[SQLITE_FCNTL_CHUNK_SIZE]]
  1003 ** The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS
  1004 ** extends and truncates the database file in chunks of a size specified
  1005 ** by the user. The fourth argument to [sqlite3_file_control()] should 
  1006 ** point to an integer (type int) containing the new chunk-size to use
  1007 ** for the nominated database. Allocating database file space in large
  1008 ** chunks (say 1MB at a time), may reduce file-system fragmentation and
  1009 ** improve performance on some systems.
  1010 **
  1011 ** <li>[[SQLITE_FCNTL_FILE_POINTER]]
  1012 ** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
  1013 ** to the [sqlite3_file] object associated with a particular database
  1014 ** connection.  See also [SQLITE_FCNTL_JOURNAL_POINTER].
  1015 **
  1016 ** <li>[[SQLITE_FCNTL_JOURNAL_POINTER]]
  1017 ** The [SQLITE_FCNTL_JOURNAL_POINTER] opcode is used to obtain a pointer
  1018 ** to the [sqlite3_file] object associated with the journal file (either
  1019 ** the [rollback journal] or the [write-ahead log]) for a particular database
  1020 ** connection.  See also [SQLITE_FCNTL_FILE_POINTER].
  1021 **
  1022 ** <li>[[SQLITE_FCNTL_SYNC_OMITTED]]
  1023 ** No longer in use.
  1024 **
  1025 ** <li>[[SQLITE_FCNTL_SYNC]]
  1026 ** The [SQLITE_FCNTL_SYNC] opcode is generated internally by SQLite and
  1027 ** sent to the VFS immediately before the xSync method is invoked on a
  1028 ** database file descriptor. Or, if the xSync method is not invoked 
  1029 ** because the user has configured SQLite with 
  1030 ** [PRAGMA synchronous | PRAGMA synchronous=OFF] it is invoked in place 
  1031 ** of the xSync method. In most cases, the pointer argument passed with
  1032 ** this file-control is NULL. However, if the database file is being synced
  1033 ** as part of a multi-database commit, the argument points to a nul-terminated
  1034 ** string containing the transactions master-journal file name. VFSes that 
  1035 ** do not need this signal should silently ignore this opcode. Applications 
  1036 ** should not call [sqlite3_file_control()] with this opcode as doing so may 
  1037 ** disrupt the operation of the specialized VFSes that do require it.  
  1038 **
  1039 ** <li>[[SQLITE_FCNTL_COMMIT_PHASETWO]]
  1040 ** The [SQLITE_FCNTL_COMMIT_PHASETWO] opcode is generated internally by SQLite
  1041 ** and sent to the VFS after a transaction has been committed immediately
  1042 ** but before the database is unlocked. VFSes that do not need this signal
  1043 ** should silently ignore this opcode. Applications should not call
  1044 ** [sqlite3_file_control()] with this opcode as doing so may disrupt the 
  1045 ** operation of the specialized VFSes that do require it.  
  1046 **
  1047 ** <li>[[SQLITE_FCNTL_WIN32_AV_RETRY]]
  1048 ** ^The [SQLITE_FCNTL_WIN32_AV_RETRY] opcode is used to configure automatic
  1049 ** retry counts and intervals for certain disk I/O operations for the
  1050 ** windows [VFS] in order to provide robustness in the presence of
  1051 ** anti-virus programs.  By default, the windows VFS will retry file read,
  1052 ** file write, and file delete operations up to 10 times, with a delay
  1053 ** of 25 milliseconds before the first retry and with the delay increasing
  1054 ** by an additional 25 milliseconds with each subsequent retry.  This
  1055 ** opcode allows these two values (10 retries and 25 milliseconds of delay)
  1056 ** to be adjusted.  The values are changed for all database connections
  1057 ** within the same process.  The argument is a pointer to an array of two
  1058 ** integers where the first integer i the new retry count and the second
  1059 ** integer is the delay.  If either integer is negative, then the setting
  1060 ** is not changed but instead the prior value of that setting is written
  1061 ** into the array entry, allowing the current retry settings to be
  1062 ** interrogated.  The zDbName parameter is ignored.
  1063 **
  1064 ** <li>[[SQLITE_FCNTL_PERSIST_WAL]]
  1065 ** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the
  1066 ** persistent [WAL | Write Ahead Log] setting.  By default, the auxiliary
  1067 ** write ahead log and shared memory files used for transaction control
  1068 ** are automatically deleted when the latest connection to the database
  1069 ** closes.  Setting persistent WAL mode causes those files to persist after
  1070 ** close.  Persisting the files is useful when other processes that do not
  1071 ** have write permission on the directory containing the database file want
  1072 ** to read the database file, as the WAL and shared memory files must exist
  1073 ** in order for the database to be readable.  The fourth parameter to
  1074 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
  1075 ** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
  1076 ** WAL mode.  If the integer is -1, then it is overwritten with the current
  1077 ** WAL persistence setting.
  1078 **
  1079 ** <li>[[SQLITE_FCNTL_POWERSAFE_OVERWRITE]]
  1080 ** ^The [SQLITE_FCNTL_POWERSAFE_OVERWRITE] opcode is used to set or query the
  1081 ** persistent "powersafe-overwrite" or "PSOW" setting.  The PSOW setting
  1082 ** determines the [SQLITE_IOCAP_POWERSAFE_OVERWRITE] bit of the
  1083 ** xDeviceCharacteristics methods. The fourth parameter to
  1084 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
  1085 ** That integer is 0 to disable zero-damage mode or 1 to enable zero-damage
  1086 ** mode.  If the integer is -1, then it is overwritten with the current
  1087 ** zero-damage mode setting.
  1088 **
  1089 ** <li>[[SQLITE_FCNTL_OVERWRITE]]
  1090 ** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
  1091 ** a write transaction to indicate that, unless it is rolled back for some
  1092 ** reason, the entire database file will be overwritten by the current 
  1093 ** transaction. This is used by VACUUM operations.
  1094 **
  1095 ** <li>[[SQLITE_FCNTL_VFSNAME]]
  1096 ** ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of
  1097 ** all [VFSes] in the VFS stack.  The names are of all VFS shims and the
  1098 ** final bottom-level VFS are written into memory obtained from 
  1099 ** [sqlite3_malloc()] and the result is stored in the char* variable
  1100 ** that the fourth parameter of [sqlite3_file_control()] points to.
  1101 ** The caller is responsible for freeing the memory when done.  As with
  1102 ** all file-control actions, there is no guarantee that this will actually
  1103 ** do anything.  Callers should initialize the char* variable to a NULL
  1104 ** pointer in case this file-control is not implemented.  This file-control
  1105 ** is intended for diagnostic use only.
  1106 **
  1107 ** <li>[[SQLITE_FCNTL_VFS_POINTER]]
  1108 ** ^The [SQLITE_FCNTL_VFS_POINTER] opcode finds a pointer to the top-level
  1109 ** [VFSes] currently in use.  ^(The argument X in
  1110 ** sqlite3_file_control(db,SQLITE_FCNTL_VFS_POINTER,X) must be
  1111 ** of type "[sqlite3_vfs] **".  This opcodes will set *X
  1112 ** to a pointer to the top-level VFS.)^
  1113 ** ^When there are multiple VFS shims in the stack, this opcode finds the
  1114 ** upper-most shim only.
  1115 **
  1116 ** <li>[[SQLITE_FCNTL_PRAGMA]]
  1117 ** ^Whenever a [PRAGMA] statement is parsed, an [SQLITE_FCNTL_PRAGMA] 
  1118 ** file control is sent to the open [sqlite3_file] object corresponding
  1119 ** to the database file to which the pragma statement refers. ^The argument
  1120 ** to the [SQLITE_FCNTL_PRAGMA] file control is an array of
  1121 ** pointers to strings (char**) in which the second element of the array
  1122 ** is the name of the pragma and the third element is the argument to the
  1123 ** pragma or NULL if the pragma has no argument.  ^The handler for an
  1124 ** [SQLITE_FCNTL_PRAGMA] file control can optionally make the first element
  1125 ** of the char** argument point to a string obtained from [sqlite3_mprintf()]
  1126 ** or the equivalent and that string will become the result of the pragma or
  1127 ** the error message if the pragma fails. ^If the
  1128 ** [SQLITE_FCNTL_PRAGMA] file control returns [SQLITE_NOTFOUND], then normal 
  1129 ** [PRAGMA] processing continues.  ^If the [SQLITE_FCNTL_PRAGMA]
  1130 ** file control returns [SQLITE_OK], then the parser assumes that the
  1131 ** VFS has handled the PRAGMA itself and the parser generates a no-op
  1132 ** prepared statement if result string is NULL, or that returns a copy
  1133 ** of the result string if the string is non-NULL.
  1134 ** ^If the [SQLITE_FCNTL_PRAGMA] file control returns
  1135 ** any result code other than [SQLITE_OK] or [SQLITE_NOTFOUND], that means
  1136 ** that the VFS encountered an error while handling the [PRAGMA] and the
  1137 ** compilation of the PRAGMA fails with an error.  ^The [SQLITE_FCNTL_PRAGMA]
  1138 ** file control occurs at the beginning of pragma statement analysis and so
  1139 ** it is able to override built-in [PRAGMA] statements.
  1140 **
  1141 ** <li>[[SQLITE_FCNTL_BUSYHANDLER]]
  1142 ** ^The [SQLITE_FCNTL_BUSYHANDLER]
  1143 ** file-control may be invoked by SQLite on the database file handle
  1144 ** shortly after it is opened in order to provide a custom VFS with access
  1145 ** to the connections busy-handler callback. The argument is of type (void **)
  1146 ** - an array of two (void *) values. The first (void *) actually points
  1147 ** to a function of type (int (*)(void *)). In order to invoke the connections
  1148 ** busy-handler, this function should be invoked with the second (void *) in
  1149 ** the array as the only argument. If it returns non-zero, then the operation
  1150 ** should be retried. If it returns zero, the custom VFS should abandon the
  1151 ** current operation.
  1152 **
  1153 ** <li>[[SQLITE_FCNTL_TEMPFILENAME]]
  1154 ** ^Application can invoke the [SQLITE_FCNTL_TEMPFILENAME] file-control
  1155 ** to have SQLite generate a
  1156 ** temporary filename using the same algorithm that is followed to generate
  1157 ** temporary filenames for TEMP tables and other internal uses.  The
  1158 ** argument should be a char** which will be filled with the filename
  1159 ** written into memory obtained from [sqlite3_malloc()].  The caller should
  1160 ** invoke [sqlite3_free()] on the result to avoid a memory leak.
  1161 **
  1162 ** <li>[[SQLITE_FCNTL_MMAP_SIZE]]
  1163 ** The [SQLITE_FCNTL_MMAP_SIZE] file control is used to query or set the
  1164 ** maximum number of bytes that will be used for memory-mapped I/O.
  1165 ** The argument is a pointer to a value of type sqlite3_int64 that
  1166 ** is an advisory maximum number of bytes in the file to memory map.  The
  1167 ** pointer is overwritten with the old value.  The limit is not changed if
  1168 ** the value originally pointed to is negative, and so the current limit 
  1169 ** can be queried by passing in a pointer to a negative number.  This
  1170 ** file-control is used internally to implement [PRAGMA mmap_size].
  1171 **
  1172 ** <li>[[SQLITE_FCNTL_TRACE]]
  1173 ** The [SQLITE_FCNTL_TRACE] file control provides advisory information
  1174 ** to the VFS about what the higher layers of the SQLite stack are doing.
  1175 ** This file control is used by some VFS activity tracing [shims].
  1176 ** The argument is a zero-terminated string.  Higher layers in the
  1177 ** SQLite stack may generate instances of this file control if
  1178 ** the [SQLITE_USE_FCNTL_TRACE] compile-time option is enabled.
  1179 **
  1180 ** <li>[[SQLITE_FCNTL_HAS_MOVED]]
  1181 ** The [SQLITE_FCNTL_HAS_MOVED] file control interprets its argument as a
  1182 ** pointer to an integer and it writes a boolean into that integer depending
  1183 ** on whether or not the file has been renamed, moved, or deleted since it
  1184 ** was first opened.
  1185 **
  1186 ** <li>[[SQLITE_FCNTL_WIN32_SET_HANDLE]]
  1187 ** The [SQLITE_FCNTL_WIN32_SET_HANDLE] opcode is used for debugging.  This
  1188 ** opcode causes the xFileControl method to swap the file handle with the one
  1189 ** pointed to by the pArg argument.  This capability is used during testing
  1190 ** and only needs to be supported when SQLITE_TEST is defined.
  1191 **
  1192 ** <li>[[SQLITE_FCNTL_WAL_BLOCK]]
  1193 ** The [SQLITE_FCNTL_WAL_BLOCK] is a signal to the VFS layer that it might
  1194 ** be advantageous to block on the next WAL lock if the lock is not immediately
  1195 ** available.  The WAL subsystem issues this signal during rare
  1196 ** circumstances in order to fix a problem with priority inversion.
  1197 ** Applications should <em>not</em> use this file-control.
  1198 **
  1199 ** <li>[[SQLITE_FCNTL_ZIPVFS]]
  1200 ** The [SQLITE_FCNTL_ZIPVFS] opcode is implemented by zipvfs only. All other
  1201 ** VFS should return SQLITE_NOTFOUND for this opcode.
  1202 **
  1203 ** <li>[[SQLITE_FCNTL_RBU]]
  1204 ** The [SQLITE_FCNTL_RBU] opcode is implemented by the special VFS used by
  1205 ** the RBU extension only.  All other VFS should return SQLITE_NOTFOUND for
  1206 ** this opcode.  
  1207 ** </ul>
  1208 */
  1209 #define SQLITE_FCNTL_LOCKSTATE               1
  1210 #define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
  1211 #define SQLITE_FCNTL_SET_LOCKPROXYFILE       3
  1212 #define SQLITE_FCNTL_LAST_ERRNO              4
  1213 #define SQLITE_FCNTL_SIZE_HINT               5
  1214 #define SQLITE_FCNTL_CHUNK_SIZE              6
  1215 #define SQLITE_FCNTL_FILE_POINTER            7
  1216 #define SQLITE_FCNTL_SYNC_OMITTED            8
  1217 #define SQLITE_FCNTL_WIN32_AV_RETRY          9
  1218 #define SQLITE_FCNTL_PERSIST_WAL            10
  1219 #define SQLITE_FCNTL_OVERWRITE              11
  1220 #define SQLITE_FCNTL_VFSNAME                12
  1221 #define SQLITE_FCNTL_POWERSAFE_OVERWRITE    13
  1222 #define SQLITE_FCNTL_PRAGMA                 14
  1223 #define SQLITE_FCNTL_BUSYHANDLER            15
  1224 #define SQLITE_FCNTL_TEMPFILENAME           16
  1225 #define SQLITE_FCNTL_MMAP_SIZE              18
  1226 #define SQLITE_FCNTL_TRACE                  19
  1227 #define SQLITE_FCNTL_HAS_MOVED              20
  1228 #define SQLITE_FCNTL_SYNC                   21
  1229 #define SQLITE_FCNTL_COMMIT_PHASETWO        22
  1230 #define SQLITE_FCNTL_WIN32_SET_HANDLE       23
  1231 #define SQLITE_FCNTL_WAL_BLOCK              24
  1232 #define SQLITE_FCNTL_ZIPVFS                 25
  1233 #define SQLITE_FCNTL_RBU                    26
  1234 #define SQLITE_FCNTL_VFS_POINTER            27
  1235 #define SQLITE_FCNTL_JOURNAL_POINTER        28
  1236 
  1237 /* deprecated names */
  1238 #define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
  1239 #define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
  1240 #define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO
  1241 
  1242 
  1243 /*
  1244 ** CAPI3REF: Mutex Handle
  1245 **
  1246 ** The mutex module within SQLite defines [sqlite3_mutex] to be an
  1247 ** abstract type for a mutex object.  The SQLite core never looks
  1248 ** at the internal representation of an [sqlite3_mutex].  It only
  1249 ** deals with pointers to the [sqlite3_mutex] object.
  1250 **
  1251 ** Mutexes are created using [sqlite3_mutex_alloc()].
  1252 */
  1253 typedef struct sqlite3_mutex sqlite3_mutex;
  1254 
  1255 /*
  1256 ** CAPI3REF: OS Interface Object
  1257 **
  1258 ** An instance of the sqlite3_vfs object defines the interface between
  1259 ** the SQLite core and the underlying operating system.  The "vfs"
  1260 ** in the name of the object stands for "virtual file system".  See
  1261 ** the [VFS | VFS documentation] for further information.
  1262 **
  1263 ** The value of the iVersion field is initially 1 but may be larger in
  1264 ** future versions of SQLite.  Additional fields may be appended to this
  1265 ** object when the iVersion value is increased.  Note that the structure
  1266 ** of the sqlite3_vfs object changes in the transaction between
  1267 ** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not
  1268 ** modified.
  1269 **
  1270 ** The szOsFile field is the size of the subclassed [sqlite3_file]
  1271 ** structure used by this VFS.  mxPathname is the maximum length of
  1272 ** a pathname in this VFS.
  1273 **
  1274 ** Registered sqlite3_vfs objects are kept on a linked list formed by
  1275 ** the pNext pointer.  The [sqlite3_vfs_register()]
  1276 ** and [sqlite3_vfs_unregister()] interfaces manage this list
  1277 ** in a thread-safe way.  The [sqlite3_vfs_find()] interface
  1278 ** searches the list.  Neither the application code nor the VFS
  1279 ** implementation should use the pNext pointer.
  1280 **
  1281 ** The pNext field is the only field in the sqlite3_vfs
  1282 ** structure that SQLite will ever modify.  SQLite will only access
  1283 ** or modify this field while holding a particular static mutex.
  1284 ** The application should never modify anything within the sqlite3_vfs
  1285 ** object once the object has been registered.
  1286 **
  1287 ** The zName field holds the name of the VFS module.  The name must
  1288 ** be unique across all VFS modules.
  1289 **
  1290 ** [[sqlite3_vfs.xOpen]]
  1291 ** ^SQLite guarantees that the zFilename parameter to xOpen
  1292 ** is either a NULL pointer or string obtained
  1293 ** from xFullPathname() with an optional suffix added.
  1294 ** ^If a suffix is added to the zFilename parameter, it will
  1295 ** consist of a single "-" character followed by no more than
  1296 ** 11 alphanumeric and/or "-" characters.
  1297 ** ^SQLite further guarantees that
  1298 ** the string will be valid and unchanged until xClose() is
  1299 ** called. Because of the previous sentence,
  1300 ** the [sqlite3_file] can safely store a pointer to the
  1301 ** filename if it needs to remember the filename for some reason.
  1302 ** If the zFilename parameter to xOpen is a NULL pointer then xOpen
  1303 ** must invent its own temporary name for the file.  ^Whenever the 
  1304 ** xFilename parameter is NULL it will also be the case that the
  1305 ** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
  1306 **
  1307 ** The flags argument to xOpen() includes all bits set in
  1308 ** the flags argument to [sqlite3_open_v2()].  Or if [sqlite3_open()]
  1309 ** or [sqlite3_open16()] is used, then flags includes at least
  1310 ** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]. 
  1311 ** If xOpen() opens a file read-only then it sets *pOutFlags to
  1312 ** include [SQLITE_OPEN_READONLY].  Other bits in *pOutFlags may be set.
  1313 **
  1314 ** ^(SQLite will also add one of the following flags to the xOpen()
  1315 ** call, depending on the object being opened:
  1316 **
  1317 ** <ul>
  1318 ** <li>  [SQLITE_OPEN_MAIN_DB]
  1319 ** <li>  [SQLITE_OPEN_MAIN_JOURNAL]
  1320 ** <li>  [SQLITE_OPEN_TEMP_DB]
  1321 ** <li>  [SQLITE_OPEN_TEMP_JOURNAL]
  1322 ** <li>  [SQLITE_OPEN_TRANSIENT_DB]
  1323 ** <li>  [SQLITE_OPEN_SUBJOURNAL]
  1324 ** <li>  [SQLITE_OPEN_MASTER_JOURNAL]
  1325 ** <li>  [SQLITE_OPEN_WAL]
  1326 ** </ul>)^
  1327 **
  1328 ** The file I/O implementation can use the object type flags to
  1329 ** change the way it deals with files.  For example, an application
  1330 ** that does not care about crash recovery or rollback might make
  1331 ** the open of a journal file a no-op.  Writes to this journal would
  1332 ** also be no-ops, and any attempt to read the journal would return
  1333 ** SQLITE_IOERR.  Or the implementation might recognize that a database
  1334 ** file will be doing page-aligned sector reads and writes in a random
  1335 ** order and set up its I/O subsystem accordingly.
  1336 **
  1337 ** SQLite might also add one of the following flags to the xOpen method:
  1338 **
  1339 ** <ul>
  1340 ** <li> [SQLITE_OPEN_DELETEONCLOSE]
  1341 ** <li> [SQLITE_OPEN_EXCLUSIVE]
  1342 ** </ul>
  1343 **
  1344 ** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
  1345 ** deleted when it is closed.  ^The [SQLITE_OPEN_DELETEONCLOSE]
  1346 ** will be set for TEMP databases and their journals, transient
  1347 ** databases, and subjournals.
  1348 **
  1349 ** ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction
  1350 ** with the [SQLITE_OPEN_CREATE] flag, which are both directly
  1351 ** analogous to the O_EXCL and O_CREAT flags of the POSIX open()
  1352 ** API.  The SQLITE_OPEN_EXCLUSIVE flag, when paired with the 
  1353 ** SQLITE_OPEN_CREATE, is used to indicate that file should always
  1354 ** be created, and that it is an error if it already exists.
  1355 ** It is <i>not</i> used to indicate the file should be opened 
  1356 ** for exclusive access.
  1357 **
  1358 ** ^At least szOsFile bytes of memory are allocated by SQLite
  1359 ** to hold the  [sqlite3_file] structure passed as the third
  1360 ** argument to xOpen.  The xOpen method does not have to
  1361 ** allocate the structure; it should just fill it in.  Note that
  1362 ** the xOpen method must set the sqlite3_file.pMethods to either
  1363 ** a valid [sqlite3_io_methods] object or to NULL.  xOpen must do
  1364 ** this even if the open fails.  SQLite expects that the sqlite3_file.pMethods
  1365 ** element will be valid after xOpen returns regardless of the success
  1366 ** or failure of the xOpen call.
  1367 **
  1368 ** [[sqlite3_vfs.xAccess]]
  1369 ** ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
  1370 ** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
  1371 ** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
  1372 ** to test whether a file is at least readable.   The file can be a
  1373 ** directory.
  1374 **
  1375 ** ^SQLite will always allocate at least mxPathname+1 bytes for the
  1376 ** output buffer xFullPathname.  The exact size of the output buffer
  1377 ** is also passed as a parameter to both  methods. If the output buffer
  1378 ** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
  1379 ** handled as a fatal error by SQLite, vfs implementations should endeavor
  1380 ** to prevent this by setting mxPathname to a sufficiently large value.
  1381 **
  1382 ** The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64()
  1383 ** interfaces are not strictly a part of the filesystem, but they are
  1384 ** included in the VFS structure for completeness.
  1385 ** The xRandomness() function attempts to return nBytes bytes
  1386 ** of good-quality randomness into zOut.  The return value is
  1387 ** the actual number of bytes of randomness obtained.
  1388 ** The xSleep() method causes the calling thread to sleep for at
  1389 ** least the number of microseconds given.  ^The xCurrentTime()
  1390 ** method returns a Julian Day Number for the current date and time as
  1391 ** a floating point value.
  1392 ** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
  1393 ** Day Number multiplied by 86400000 (the number of milliseconds in 
  1394 ** a 24-hour day).  
  1395 ** ^SQLite will use the xCurrentTimeInt64() method to get the current
  1396 ** date and time if that method is available (if iVersion is 2 or 
  1397 ** greater and the function pointer is not NULL) and will fall back
  1398 ** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
  1399 **
  1400 ** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
  1401 ** are not used by the SQLite core.  These optional interfaces are provided
  1402 ** by some VFSes to facilitate testing of the VFS code. By overriding 
  1403 ** system calls with functions under its control, a test program can
  1404 ** simulate faults and error conditions that would otherwise be difficult
  1405 ** or impossible to induce.  The set of system calls that can be overridden
  1406 ** varies from one VFS to another, and from one version of the same VFS to the
  1407 ** next.  Applications that use these interfaces must be prepared for any
  1408 ** or all of these interfaces to be NULL or for their behavior to change
  1409 ** from one release to the next.  Applications must not attempt to access
  1410 ** any of these methods if the iVersion of the VFS is less than 3.
  1411 */
  1412 typedef struct sqlite3_vfs sqlite3_vfs;
  1413 typedef void (*sqlite3_syscall_ptr)(void);
  1414 struct sqlite3_vfs {
  1415   int iVersion;            /* Structure version number (currently 3) */
  1416   int szOsFile;            /* Size of subclassed sqlite3_file */
  1417   int mxPathname;          /* Maximum file pathname length */
  1418   sqlite3_vfs *pNext;      /* Next registered VFS */
  1419   const char *zName;       /* Name of this virtual file system */
  1420   void *pAppData;          /* Pointer to application-specific data */
  1421   int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
  1422                int flags, int *pOutFlags);
  1423   int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
  1424   int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
  1425   int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
  1426   void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
  1427   void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
  1428   void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
  1429   void (*xDlClose)(sqlite3_vfs*, void*);
  1430   int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
  1431   int (*xSleep)(sqlite3_vfs*, int microseconds);
  1432   int (*xCurrentTime)(sqlite3_vfs*, double*);
  1433   int (*xGetLastError)(sqlite3_vfs*, int, char *);
  1434   /*
  1435   ** The methods above are in version 1 of the sqlite_vfs object
  1436   ** definition.  Those that follow are added in version 2 or later
  1437   */
  1438   int (*xCurrentTimeInt64)(sqlite3_vfs*, sqlite3_int64*);
  1439   /*
  1440   ** The methods above are in versions 1 and 2 of the sqlite_vfs object.
  1441   ** Those below are for version 3 and greater.
  1442   */
  1443   int (*xSetSystemCall)(sqlite3_vfs*, const char *zName, sqlite3_syscall_ptr);
  1444   sqlite3_syscall_ptr (*xGetSystemCall)(sqlite3_vfs*, const char *zName);
  1445   const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
  1446   /*
  1447   ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
  1448   ** New fields may be appended in figure versions.  The iVersion
  1449   ** value will increment whenever this happens. 
  1450   */
  1451 };
  1452 
  1453 /*
  1454 ** CAPI3REF: Flags for the xAccess VFS method
  1455 **
  1456 ** These integer constants can be used as the third parameter to
  1457 ** the xAccess method of an [sqlite3_vfs] object.  They determine
  1458 ** what kind of permissions the xAccess method is looking for.
  1459 ** With SQLITE_ACCESS_EXISTS, the xAccess method
  1460 ** simply checks whether the file exists.
  1461 ** With SQLITE_ACCESS_READWRITE, the xAccess method
  1462 ** checks whether the named directory is both readable and writable
  1463 ** (in other words, if files can be added, removed, and renamed within
  1464 ** the directory).
  1465 ** The SQLITE_ACCESS_READWRITE constant is currently used only by the
  1466 ** [temp_store_directory pragma], though this could change in a future
  1467 ** release of SQLite.
  1468 ** With SQLITE_ACCESS_READ, the xAccess method
  1469 ** checks whether the file is readable.  The SQLITE_ACCESS_READ constant is
  1470 ** currently unused, though it might be used in a future release of
  1471 ** SQLite.
  1472 */
  1473 #define SQLITE_ACCESS_EXISTS    0
  1474 #define SQLITE_ACCESS_READWRITE 1   /* Used by PRAGMA temp_store_directory */
  1475 #define SQLITE_ACCESS_READ      2   /* Unused */
  1476 
  1477 /*
  1478 ** CAPI3REF: Flags for the xShmLock VFS method
  1479 **
  1480 ** These integer constants define the various locking operations
  1481 ** allowed by the xShmLock method of [sqlite3_io_methods].  The
  1482 ** following are the only legal combinations of flags to the
  1483 ** xShmLock method:
  1484 **
  1485 ** <ul>
  1486 ** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_SHARED
  1487 ** <li>  SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE
  1488 ** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED
  1489 ** <li>  SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE
  1490 ** </ul>
  1491 **
  1492 ** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
  1493 ** was given on the corresponding lock.  
  1494 **
  1495 ** The xShmLock method can transition between unlocked and SHARED or
  1496 ** between unlocked and EXCLUSIVE.  It cannot transition between SHARED
  1497 ** and EXCLUSIVE.
  1498 */
  1499 #define SQLITE_SHM_UNLOCK       1
  1500 #define SQLITE_SHM_LOCK         2
  1501 #define SQLITE_SHM_SHARED       4
  1502 #define SQLITE_SHM_EXCLUSIVE    8
  1503 
  1504 /*
  1505 ** CAPI3REF: Maximum xShmLock index
  1506 **
  1507 ** The xShmLock method on [sqlite3_io_methods] may use values
  1508 ** between 0 and this upper bound as its "offset" argument.
  1509 ** The SQLite core will never attempt to acquire or release a
  1510 ** lock outside of this range
  1511 */
  1512 #define SQLITE_SHM_NLOCK        8
  1513 
  1514 
  1515 /*
  1516 ** CAPI3REF: Initialize The SQLite Library
  1517 **
  1518 ** ^The sqlite3_initialize() routine initializes the
  1519 ** SQLite library.  ^The sqlite3_shutdown() routine
  1520 ** deallocates any resources that were allocated by sqlite3_initialize().
  1521 ** These routines are designed to aid in process initialization and
  1522 ** shutdown on embedded systems.  Workstation applications using
  1523 ** SQLite normally do not need to invoke either of these routines.
  1524 **
  1525 ** A call to sqlite3_initialize() is an "effective" call if it is
  1526 ** the first time sqlite3_initialize() is invoked during the lifetime of
  1527 ** the process, or if it is the first time sqlite3_initialize() is invoked
  1528 ** following a call to sqlite3_shutdown().  ^(Only an effective call
  1529 ** of sqlite3_initialize() does any initialization.  All other calls
  1530 ** are harmless no-ops.)^
  1531 **
  1532 ** A call to sqlite3_shutdown() is an "effective" call if it is the first
  1533 ** call to sqlite3_shutdown() since the last sqlite3_initialize().  ^(Only
  1534 ** an effective call to sqlite3_shutdown() does any deinitialization.
  1535 ** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^
  1536 **
  1537 ** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()
  1538 ** is not.  The sqlite3_shutdown() interface must only be called from a
  1539 ** single thread.  All open [database connections] must be closed and all
  1540 ** other SQLite resources must be deallocated prior to invoking
  1541 ** sqlite3_shutdown().
  1542 **
  1543 ** Among other things, ^sqlite3_initialize() will invoke
  1544 ** sqlite3_os_init().  Similarly, ^sqlite3_shutdown()
  1545 ** will invoke sqlite3_os_end().
  1546 **
  1547 ** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.
  1548 ** ^If for some reason, sqlite3_initialize() is unable to initialize
  1549 ** the library (perhaps it is unable to allocate a needed resource such
  1550 ** as a mutex) it returns an [error code] other than [SQLITE_OK].
  1551 **
  1552 ** ^The sqlite3_initialize() routine is called internally by many other
  1553 ** SQLite interfaces so that an application usually does not need to
  1554 ** invoke sqlite3_initialize() directly.  For example, [sqlite3_open()]
  1555 ** calls sqlite3_initialize() so the SQLite library will be automatically
  1556 ** initialized when [sqlite3_open()] is called if it has not be initialized
  1557 ** already.  ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
  1558 ** compile-time option, then the automatic calls to sqlite3_initialize()
  1559 ** are omitted and the application must call sqlite3_initialize() directly
  1560 ** prior to using any other SQLite interface.  For maximum portability,
  1561 ** it is recommended that applications always invoke sqlite3_initialize()
  1562 ** directly prior to using any other SQLite interface.  Future releases
  1563 ** of SQLite may require this.  In other words, the behavior exhibited
  1564 ** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
  1565 ** default behavior in some future release of SQLite.
  1566 **
  1567 ** The sqlite3_os_init() routine does operating-system specific
  1568 ** initialization of the SQLite library.  The sqlite3_os_end()
  1569 ** routine undoes the effect of sqlite3_os_init().  Typical tasks
  1570 ** performed by these routines include allocation or deallocation
  1571 ** of static resources, initialization of global variables,
  1572 ** setting up a default [sqlite3_vfs] module, or setting up
  1573 ** a default configuration using [sqlite3_config()].
  1574 **
  1575 ** The application should never invoke either sqlite3_os_init()
  1576 ** or sqlite3_os_end() directly.  The application should only invoke
  1577 ** sqlite3_initialize() and sqlite3_shutdown().  The sqlite3_os_init()
  1578 ** interface is called automatically by sqlite3_initialize() and
  1579 ** sqlite3_os_end() is called by sqlite3_shutdown().  Appropriate
  1580 ** implementations for sqlite3_os_init() and sqlite3_os_end()
  1581 ** are built into SQLite when it is compiled for Unix, Windows, or OS/2.
  1582 ** When [custom builds | built for other platforms]
  1583 ** (using the [SQLITE_OS_OTHER=1] compile-time
  1584 ** option) the application must supply a suitable implementation for
  1585 ** sqlite3_os_init() and sqlite3_os_end().  An application-supplied
  1586 ** implementation of sqlite3_os_init() or sqlite3_os_end()
  1587 ** must return [SQLITE_OK] on success and some other [error code] upon
  1588 ** failure.
  1589 */
  1590 SQLITE_API int SQLITE_STDCALL sqlite3_initialize(void);
  1591 SQLITE_API int SQLITE_STDCALL sqlite3_shutdown(void);
  1592 SQLITE_API int SQLITE_STDCALL sqlite3_os_init(void);
  1593 SQLITE_API int SQLITE_STDCALL sqlite3_os_end(void);
  1594 
  1595 /*
  1596 ** CAPI3REF: Configuring The SQLite Library
  1597 **
  1598 ** The sqlite3_config() interface is used to make global configuration
  1599 ** changes to SQLite in order to tune SQLite to the specific needs of
  1600 ** the application.  The default configuration is recommended for most
  1601 ** applications and so this routine is usually not necessary.  It is
  1602 ** provided to support rare applications with unusual needs.
  1603 **
  1604 ** <b>The sqlite3_config() interface is not threadsafe. The application
  1605 ** must ensure that no other SQLite interfaces are invoked by other
  1606 ** threads while sqlite3_config() is running.</b>
  1607 **
  1608 ** The sqlite3_config() interface
  1609 ** may only be invoked prior to library initialization using
  1610 ** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
  1611 ** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
  1612 ** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.
  1613 ** Note, however, that ^sqlite3_config() can be called as part of the
  1614 ** implementation of an application-defined [sqlite3_os_init()].
  1615 **
  1616 ** The first argument to sqlite3_config() is an integer
  1617 ** [configuration option] that determines
  1618 ** what property of SQLite is to be configured.  Subsequent arguments
  1619 ** vary depending on the [configuration option]
  1620 ** in the first argument.
  1621 **
  1622 ** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
  1623 ** ^If the option is unknown or SQLite is unable to set the option
  1624 ** then this routine returns a non-zero [error code].
  1625 */
  1626 SQLITE_API int SQLITE_CDECL sqlite3_config(int, ...);
  1627 
  1628 /*
  1629 ** CAPI3REF: Configure database connections
  1630 ** METHOD: sqlite3
  1631 **
  1632 ** The sqlite3_db_config() interface is used to make configuration
  1633 ** changes to a [database connection].  The interface is similar to
  1634 ** [sqlite3_config()] except that the changes apply to a single
  1635 ** [database connection] (specified in the first argument).
  1636 **
  1637 ** The second argument to sqlite3_db_config(D,V,...)  is the
  1638 ** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code 
  1639 ** that indicates what aspect of the [database connection] is being configured.
  1640 ** Subsequent arguments vary depending on the configuration verb.
  1641 **
  1642 ** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
  1643 ** the call is considered successful.
  1644 */
  1645 SQLITE_API int SQLITE_CDECL sqlite3_db_config(sqlite3*, int op, ...);
  1646 
  1647 /*
  1648 ** CAPI3REF: Memory Allocation Routines
  1649 **
  1650 ** An instance of this object defines the interface between SQLite
  1651 ** and low-level memory allocation routines.
  1652 **
  1653 ** This object is used in only one place in the SQLite interface.
  1654 ** A pointer to an instance of this object is the argument to
  1655 ** [sqlite3_config()] when the configuration option is
  1656 ** [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC].  
  1657 ** By creating an instance of this object
  1658 ** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])
  1659 ** during configuration, an application can specify an alternative
  1660 ** memory allocation subsystem for SQLite to use for all of its
  1661 ** dynamic memory needs.
  1662 **
  1663 ** Note that SQLite comes with several [built-in memory allocators]
  1664 ** that are perfectly adequate for the overwhelming majority of applications
  1665 ** and that this object is only useful to a tiny minority of applications
  1666 ** with specialized memory allocation requirements.  This object is
  1667 ** also used during testing of SQLite in order to specify an alternative
  1668 ** memory allocator that simulates memory out-of-memory conditions in
  1669 ** order to verify that SQLite recovers gracefully from such
  1670 ** conditions.
  1671 **
  1672 ** The xMalloc, xRealloc, and xFree methods must work like the
  1673 ** malloc(), realloc() and free() functions from the standard C library.
  1674 ** ^SQLite guarantees that the second argument to
  1675 ** xRealloc is always a value returned by a prior call to xRoundup.
  1676 **
  1677 ** xSize should return the allocated size of a memory allocation
  1678 ** previously obtained from xMalloc or xRealloc.  The allocated size
  1679 ** is always at least as big as the requested size but may be larger.
  1680 **
  1681 ** The xRoundup method returns what would be the allocated size of
  1682 ** a memory allocation given a particular requested size.  Most memory
  1683 ** allocators round up memory allocations at least to the next multiple
  1684 ** of 8.  Some allocators round up to a larger multiple or to a power of 2.
  1685 ** Every memory allocation request coming in through [sqlite3_malloc()]
  1686 ** or [sqlite3_realloc()] first calls xRoundup.  If xRoundup returns 0, 
  1687 ** that causes the corresponding memory allocation to fail.
  1688 **
  1689 ** The xInit method initializes the memory allocator.  For example,
  1690 ** it might allocate any require mutexes or initialize internal data
  1691 ** structures.  The xShutdown method is invoked (indirectly) by
  1692 ** [sqlite3_shutdown()] and should deallocate any resources acquired
  1693 ** by xInit.  The pAppData pointer is used as the only parameter to
  1694 ** xInit and xShutdown.
  1695 **
  1696 ** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes
  1697 ** the xInit method, so the xInit method need not be threadsafe.  The
  1698 ** xShutdown method is only called from [sqlite3_shutdown()] so it does
  1699 ** not need to be threadsafe either.  For all other methods, SQLite
  1700 ** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the
  1701 ** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which
  1702 ** it is by default) and so the methods are automatically serialized.
  1703 ** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other
  1704 ** methods must be threadsafe or else make their own arrangements for
  1705 ** serialization.
  1706 **
  1707 ** SQLite will never invoke xInit() more than once without an intervening
  1708 ** call to xShutdown().
  1709 */
  1710 typedef struct sqlite3_mem_methods sqlite3_mem_methods;
  1711 struct sqlite3_mem_methods {
  1712   void *(*xMalloc)(int);         /* Memory allocation function */
  1713   void (*xFree)(void*);          /* Free a prior allocation */
  1714   void *(*xRealloc)(void*,int);  /* Resize an allocation */
  1715   int (*xSize)(void*);           /* Return the size of an allocation */
  1716   int (*xRoundup)(int);          /* Round up request size to allocation size */
  1717   int (*xInit)(void*);           /* Initialize the memory allocator */
  1718   void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
  1719   void *pAppData;                /* Argument to xInit() and xShutdown() */
  1720 };
  1721 
  1722 /*
  1723 ** CAPI3REF: Configuration Options
  1724 ** KEYWORDS: {configuration option}
  1725 **
  1726 ** These constants are the available integer configuration options that
  1727 ** can be passed as the first argument to the [sqlite3_config()] interface.
  1728 **
  1729 ** New configuration options may be added in future releases of SQLite.
  1730 ** Existing configuration options might be discontinued.  Applications
  1731 ** should check the return code from [sqlite3_config()] to make sure that
  1732 ** the call worked.  The [sqlite3_config()] interface will return a
  1733 ** non-zero [error code] if a discontinued or unsupported configuration option
  1734 ** is invoked.
  1735 **
  1736 ** <dl>
  1737 ** [[SQLITE_CONFIG_SINGLETHREAD]] <dt>SQLITE_CONFIG_SINGLETHREAD</dt>
  1738 ** <dd>There are no arguments to this option.  ^This option sets the
  1739 ** [threading mode] to Single-thread.  In other words, it disables
  1740 ** all mutexing and puts SQLite into a mode where it can only be used
  1741 ** by a single thread.   ^If SQLite is compiled with
  1742 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1743 ** it is not possible to change the [threading mode] from its default
  1744 ** value of Single-thread and so [sqlite3_config()] will return 
  1745 ** [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD
  1746 ** configuration option.</dd>
  1747 **
  1748 ** [[SQLITE_CONFIG_MULTITHREAD]] <dt>SQLITE_CONFIG_MULTITHREAD</dt>
  1749 ** <dd>There are no arguments to this option.  ^This option sets the
  1750 ** [threading mode] to Multi-thread.  In other words, it disables
  1751 ** mutexing on [database connection] and [prepared statement] objects.
  1752 ** The application is responsible for serializing access to
  1753 ** [database connections] and [prepared statements].  But other mutexes
  1754 ** are enabled so that SQLite will be safe to use in a multi-threaded
  1755 ** environment as long as no two threads attempt to use the same
  1756 ** [database connection] at the same time.  ^If SQLite is compiled with
  1757 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1758 ** it is not possible to set the Multi-thread [threading mode] and
  1759 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
  1760 ** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>
  1761 **
  1762 ** [[SQLITE_CONFIG_SERIALIZED]] <dt>SQLITE_CONFIG_SERIALIZED</dt>
  1763 ** <dd>There are no arguments to this option.  ^This option sets the
  1764 ** [threading mode] to Serialized. In other words, this option enables
  1765 ** all mutexes including the recursive
  1766 ** mutexes on [database connection] and [prepared statement] objects.
  1767 ** In this mode (which is the default when SQLite is compiled with
  1768 ** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
  1769 ** to [database connections] and [prepared statements] so that the
  1770 ** application is free to use the same [database connection] or the
  1771 ** same [prepared statement] in different threads at the same time.
  1772 ** ^If SQLite is compiled with
  1773 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1774 ** it is not possible to set the Serialized [threading mode] and
  1775 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
  1776 ** SQLITE_CONFIG_SERIALIZED configuration option.</dd>
  1777 **
  1778 ** [[SQLITE_CONFIG_MALLOC]] <dt>SQLITE_CONFIG_MALLOC</dt>
  1779 ** <dd> ^(The SQLITE_CONFIG_MALLOC option takes a single argument which is 
  1780 ** a pointer to an instance of the [sqlite3_mem_methods] structure.
  1781 ** The argument specifies
  1782 ** alternative low-level memory allocation routines to be used in place of
  1783 ** the memory allocation routines built into SQLite.)^ ^SQLite makes
  1784 ** its own private copy of the content of the [sqlite3_mem_methods] structure
  1785 ** before the [sqlite3_config()] call returns.</dd>
  1786 **
  1787 ** [[SQLITE_CONFIG_GETMALLOC]] <dt>SQLITE_CONFIG_GETMALLOC</dt>
  1788 ** <dd> ^(The SQLITE_CONFIG_GETMALLOC option takes a single argument which
  1789 ** is a pointer to an instance of the [sqlite3_mem_methods] structure.
  1790 ** The [sqlite3_mem_methods]
  1791 ** structure is filled with the currently defined memory allocation routines.)^
  1792 ** This option can be used to overload the default memory allocation
  1793 ** routines with a wrapper that simulations memory allocation failure or
  1794 ** tracks memory usage, for example. </dd>
  1795 **
  1796 ** [[SQLITE_CONFIG_MEMSTATUS]] <dt>SQLITE_CONFIG_MEMSTATUS</dt>
  1797 ** <dd> ^The SQLITE_CONFIG_MEMSTATUS option takes single argument of type int,
  1798 ** interpreted as a boolean, which enables or disables the collection of
  1799 ** memory allocation statistics. ^(When memory allocation statistics are
  1800 ** disabled, the following SQLite interfaces become non-operational:
  1801 **   <ul>
  1802 **   <li> [sqlite3_memory_used()]
  1803 **   <li> [sqlite3_memory_highwater()]
  1804 **   <li> [sqlite3_soft_heap_limit64()]
  1805 **   <li> [sqlite3_status64()]
  1806 **   </ul>)^
  1807 ** ^Memory allocation statistics are enabled by default unless SQLite is
  1808 ** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
  1809 ** allocation statistics are disabled by default.
  1810 ** </dd>
  1811 **
  1812 ** [[SQLITE_CONFIG_SCRATCH]] <dt>SQLITE_CONFIG_SCRATCH</dt>
  1813 ** <dd> ^The SQLITE_CONFIG_SCRATCH option specifies a static memory buffer
  1814 ** that SQLite can use for scratch memory.  ^(There are three arguments
  1815 ** to SQLITE_CONFIG_SCRATCH:  A pointer an 8-byte
  1816 ** aligned memory buffer from which the scratch allocations will be
  1817 ** drawn, the size of each scratch allocation (sz),
  1818 ** and the maximum number of scratch allocations (N).)^
  1819 ** The first argument must be a pointer to an 8-byte aligned buffer
  1820 ** of at least sz*N bytes of memory.
  1821 ** ^SQLite will not use more than one scratch buffers per thread.
  1822 ** ^SQLite will never request a scratch buffer that is more than 6
  1823 ** times the database page size.
  1824 ** ^If SQLite needs needs additional
  1825 ** scratch memory beyond what is provided by this configuration option, then 
  1826 ** [sqlite3_malloc()] will be used to obtain the memory needed.<p>
  1827 ** ^When the application provides any amount of scratch memory using
  1828 ** SQLITE_CONFIG_SCRATCH, SQLite avoids unnecessary large
  1829 ** [sqlite3_malloc|heap allocations].
  1830 ** This can help [Robson proof|prevent memory allocation failures] due to heap
  1831 ** fragmentation in low-memory embedded systems.
  1832 ** </dd>
  1833 **
  1834 ** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
  1835 ** <dd> ^The SQLITE_CONFIG_PAGECACHE option specifies a memory pool
  1836 ** that SQLite can use for the database page cache with the default page
  1837 ** cache implementation.  
  1838 ** This configuration option is a no-op if an application-define page
  1839 ** cache implementation is loaded using the [SQLITE_CONFIG_PCACHE2].
  1840 ** ^There are three arguments to SQLITE_CONFIG_PAGECACHE: A pointer to
  1841 ** 8-byte aligned memory (pMem), the size of each page cache line (sz),
  1842 ** and the number of cache lines (N).
  1843 ** The sz argument should be the size of the largest database page
  1844 ** (a power of two between 512 and 65536) plus some extra bytes for each
  1845 ** page header.  ^The number of extra bytes needed by the page header
  1846 ** can be determined using [SQLITE_CONFIG_PCACHE_HDRSZ].
  1847 ** ^It is harmless, apart from the wasted memory,
  1848 ** for the sz parameter to be larger than necessary.  The pMem
  1849 ** argument must be either a NULL pointer or a pointer to an 8-byte
  1850 ** aligned block of memory of at least sz*N bytes, otherwise
  1851 ** subsequent behavior is undefined.
  1852 ** ^When pMem is not NULL, SQLite will strive to use the memory provided
  1853 ** to satisfy page cache needs, falling back to [sqlite3_malloc()] if
  1854 ** a page cache line is larger than sz bytes or if all of the pMem buffer
  1855 ** is exhausted.
  1856 ** ^If pMem is NULL and N is non-zero, then each database connection
  1857 ** does an initial bulk allocation for page cache memory
  1858 ** from [sqlite3_malloc()] sufficient for N cache lines if N is positive or
  1859 ** of -1024*N bytes if N is negative, . ^If additional
  1860 ** page cache memory is needed beyond what is provided by the initial
  1861 ** allocation, then SQLite goes to [sqlite3_malloc()] separately for each
  1862 ** additional cache line. </dd>
  1863 **
  1864 ** [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt>
  1865 ** <dd> ^The SQLITE_CONFIG_HEAP option specifies a static memory buffer 
  1866 ** that SQLite will use for all of its dynamic memory allocation needs
  1867 ** beyond those provided for by [SQLITE_CONFIG_SCRATCH] and
  1868 ** [SQLITE_CONFIG_PAGECACHE].
  1869 ** ^The SQLITE_CONFIG_HEAP option is only available if SQLite is compiled
  1870 ** with either [SQLITE_ENABLE_MEMSYS3] or [SQLITE_ENABLE_MEMSYS5] and returns
  1871 ** [SQLITE_ERROR] if invoked otherwise.
  1872 ** ^There are three arguments to SQLITE_CONFIG_HEAP:
  1873 ** An 8-byte aligned pointer to the memory,
  1874 ** the number of bytes in the memory buffer, and the minimum allocation size.
  1875 ** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
  1876 ** to using its default memory allocator (the system malloc() implementation),
  1877 ** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
  1878 ** memory pointer is not NULL then the alternative memory
  1879 ** allocator is engaged to handle all of SQLites memory allocation needs.
  1880 ** The first pointer (the memory pointer) must be aligned to an 8-byte
  1881 ** boundary or subsequent behavior of SQLite will be undefined.
  1882 ** The minimum allocation size is capped at 2**12. Reasonable values
  1883 ** for the minimum allocation size are 2**5 through 2**8.</dd>
  1884 **
  1885 ** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
  1886 ** <dd> ^(The SQLITE_CONFIG_MUTEX option takes a single argument which is a
  1887 ** pointer to an instance of the [sqlite3_mutex_methods] structure.
  1888 ** The argument specifies alternative low-level mutex routines to be used
  1889 ** in place the mutex routines built into SQLite.)^  ^SQLite makes a copy of
  1890 ** the content of the [sqlite3_mutex_methods] structure before the call to
  1891 ** [sqlite3_config()] returns. ^If SQLite is compiled with
  1892 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1893 ** the entire mutexing subsystem is omitted from the build and hence calls to
  1894 ** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
  1895 ** return [SQLITE_ERROR].</dd>
  1896 **
  1897 ** [[SQLITE_CONFIG_GETMUTEX]] <dt>SQLITE_CONFIG_GETMUTEX</dt>
  1898 ** <dd> ^(The SQLITE_CONFIG_GETMUTEX option takes a single argument which
  1899 ** is a pointer to an instance of the [sqlite3_mutex_methods] structure.  The
  1900 ** [sqlite3_mutex_methods]
  1901 ** structure is filled with the currently defined mutex routines.)^
  1902 ** This option can be used to overload the default mutex allocation
  1903 ** routines with a wrapper used to track mutex usage for performance
  1904 ** profiling or testing, for example.   ^If SQLite is compiled with
  1905 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
  1906 ** the entire mutexing subsystem is omitted from the build and hence calls to
  1907 ** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will
  1908 ** return [SQLITE_ERROR].</dd>
  1909 **
  1910 ** [[SQLITE_CONFIG_LOOKASIDE]] <dt>SQLITE_CONFIG_LOOKASIDE</dt>
  1911 ** <dd> ^(The SQLITE_CONFIG_LOOKASIDE option takes two arguments that determine
  1912 ** the default size of lookaside memory on each [database connection].
  1913 ** The first argument is the
  1914 ** size of each lookaside buffer slot and the second is the number of
  1915 ** slots allocated to each database connection.)^  ^(SQLITE_CONFIG_LOOKASIDE
  1916 ** sets the <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]
  1917 ** option to [sqlite3_db_config()] can be used to change the lookaside
  1918 ** configuration on individual connections.)^ </dd>
  1919 **
  1920 ** [[SQLITE_CONFIG_PCACHE2]] <dt>SQLITE_CONFIG_PCACHE2</dt>
  1921 ** <dd> ^(The SQLITE_CONFIG_PCACHE2 option takes a single argument which is 
  1922 ** a pointer to an [sqlite3_pcache_methods2] object.  This object specifies
  1923 ** the interface to a custom page cache implementation.)^
  1924 ** ^SQLite makes a copy of the [sqlite3_pcache_methods2] object.</dd>
  1925 **
  1926 ** [[SQLITE_CONFIG_GETPCACHE2]] <dt>SQLITE_CONFIG_GETPCACHE2</dt>
  1927 ** <dd> ^(The SQLITE_CONFIG_GETPCACHE2 option takes a single argument which
  1928 ** is a pointer to an [sqlite3_pcache_methods2] object.  SQLite copies of
  1929 ** the current page cache implementation into that object.)^ </dd>
  1930 **
  1931 ** [[SQLITE_CONFIG_LOG]] <dt>SQLITE_CONFIG_LOG</dt>
  1932 ** <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite
  1933 ** global [error log].
  1934 ** (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
  1935 ** function with a call signature of void(*)(void*,int,const char*), 
  1936 ** and a pointer to void. ^If the function pointer is not NULL, it is
  1937 ** invoked by [sqlite3_log()] to process each logging event.  ^If the
  1938 ** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
  1939 ** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
  1940 ** passed through as the first parameter to the application-defined logger
  1941 ** function whenever that function is invoked.  ^The second parameter to
  1942 ** the logger function is a copy of the first parameter to the corresponding
  1943 ** [sqlite3_log()] call and is intended to be a [result code] or an
  1944 ** [extended result code].  ^The third parameter passed to the logger is
  1945 ** log message after formatting via [sqlite3_snprintf()].
  1946 ** The SQLite logging interface is not reentrant; the logger function
  1947 ** supplied by the application must not invoke any SQLite interface.
  1948 ** In a multi-threaded application, the application-defined logger
  1949 ** function must be threadsafe. </dd>
  1950 **
  1951 ** [[SQLITE_CONFIG_URI]] <dt>SQLITE_CONFIG_URI
  1952 ** <dd>^(The SQLITE_CONFIG_URI option takes a single argument of type int.
  1953 ** If non-zero, then URI handling is globally enabled. If the parameter is zero,
  1954 ** then URI handling is globally disabled.)^ ^If URI handling is globally
  1955 ** enabled, all filenames passed to [sqlite3_open()], [sqlite3_open_v2()],
  1956 ** [sqlite3_open16()] or
  1957 ** specified as part of [ATTACH] commands are interpreted as URIs, regardless
  1958 ** of whether or not the [SQLITE_OPEN_URI] flag is set when the database
  1959 ** connection is opened. ^If it is globally disabled, filenames are
  1960 ** only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the
  1961 ** database connection is opened. ^(By default, URI handling is globally
  1962 ** disabled. The default value may be changed by compiling with the
  1963 ** [SQLITE_USE_URI] symbol defined.)^
  1964 **
  1965 ** [[SQLITE_CONFIG_COVERING_INDEX_SCAN]] <dt>SQLITE_CONFIG_COVERING_INDEX_SCAN
  1966 ** <dd>^The SQLITE_CONFIG_COVERING_INDEX_SCAN option takes a single integer
  1967 ** argument which is interpreted as a boolean in order to enable or disable
  1968 ** the use of covering indices for full table scans in the query optimizer.
  1969 ** ^The default setting is determined
  1970 ** by the [SQLITE_ALLOW_COVERING_INDEX_SCAN] compile-time option, or is "on"
  1971 ** if that compile-time option is omitted.
  1972 ** The ability to disable the use of covering indices for full table scans
  1973 ** is because some incorrectly coded legacy applications might malfunction
  1974 ** when the optimization is enabled.  Providing the ability to
  1975 ** disable the optimization allows the older, buggy application code to work
  1976 ** without change even with newer versions of SQLite.
  1977 **
  1978 ** [[SQLITE_CONFIG_PCACHE]] [[SQLITE_CONFIG_GETPCACHE]]
  1979 ** <dt>SQLITE_CONFIG_PCACHE and SQLITE_CONFIG_GETPCACHE
  1980 ** <dd> These options are obsolete and should not be used by new code.
  1981 ** They are retained for backwards compatibility but are now no-ops.
  1982 ** </dd>
  1983 **
  1984 ** [[SQLITE_CONFIG_SQLLOG]]
  1985 ** <dt>SQLITE_CONFIG_SQLLOG
  1986 ** <dd>This option is only available if sqlite is compiled with the
  1987 ** [SQLITE_ENABLE_SQLLOG] pre-processor macro defined. The first argument should
  1988 ** be a pointer to a function of type void(*)(void*,sqlite3*,const char*, int).
  1989 ** The second should be of type (void*). The callback is invoked by the library
  1990 ** in three separate circumstances, identified by the value passed as the
  1991 ** fourth parameter. If the fourth parameter is 0, then the database connection
  1992 ** passed as the second argument has just been opened. The third argument
  1993 ** points to a buffer containing the name of the main database file. If the
  1994 ** fourth parameter is 1, then the SQL statement that the third parameter
  1995 ** points to has just been executed. Or, if the fourth parameter is 2, then
  1996 ** the connection being passed as the second parameter is being closed. The
  1997 ** third parameter is passed NULL In this case.  An example of using this
  1998 ** configuration option can be seen in the "test_sqllog.c" source file in
  1999 ** the canonical SQLite source tree.</dd>
  2000 **
  2001 ** [[SQLITE_CONFIG_MMAP_SIZE]]
  2002 ** <dt>SQLITE_CONFIG_MMAP_SIZE
  2003 ** <dd>^SQLITE_CONFIG_MMAP_SIZE takes two 64-bit integer (sqlite3_int64) values
  2004 ** that are the default mmap size limit (the default setting for
  2005 ** [PRAGMA mmap_size]) and the maximum allowed mmap size limit.
  2006 ** ^The default setting can be overridden by each database connection using
  2007 ** either the [PRAGMA mmap_size] command, or by using the
  2008 ** [SQLITE_FCNTL_MMAP_SIZE] file control.  ^(The maximum allowed mmap size
  2009 ** will be silently truncated if necessary so that it does not exceed the
  2010 ** compile-time maximum mmap size set by the
  2011 ** [SQLITE_MAX_MMAP_SIZE] compile-time option.)^
  2012 ** ^If either argument to this option is negative, then that argument is
  2013 ** changed to its compile-time default.
  2014 **
  2015 ** [[SQLITE_CONFIG_WIN32_HEAPSIZE]]
  2016 ** <dt>SQLITE_CONFIG_WIN32_HEAPSIZE
  2017 ** <dd>^The SQLITE_CONFIG_WIN32_HEAPSIZE option is only available if SQLite is
  2018 ** compiled for Windows with the [SQLITE_WIN32_MALLOC] pre-processor macro
  2019 ** defined. ^SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value
  2020 ** that specifies the maximum size of the created heap.
  2021 **
  2022 ** [[SQLITE_CONFIG_PCACHE_HDRSZ]]
  2023 ** <dt>SQLITE_CONFIG_PCACHE_HDRSZ
  2024 ** <dd>^The SQLITE_CONFIG_PCACHE_HDRSZ option takes a single parameter which
  2025 ** is a pointer to an integer and writes into that integer the number of extra
  2026 ** bytes per page required for each page in [SQLITE_CONFIG_PAGECACHE].
  2027 ** The amount of extra space required can change depending on the compiler,
  2028 ** target platform, and SQLite version.
  2029 **
  2030 ** [[SQLITE_CONFIG_PMASZ]]
  2031 ** <dt>SQLITE_CONFIG_PMASZ
  2032 ** <dd>^The SQLITE_CONFIG_PMASZ option takes a single parameter which
  2033 ** is an unsigned integer and sets the "Minimum PMA Size" for the multithreaded
  2034 ** sorter to that integer.  The default minimum PMA Size is set by the
  2035 ** [SQLITE_SORTER_PMASZ] compile-time option.  New threads are launched
  2036 ** to help with sort operations when multithreaded sorting
  2037 ** is enabled (using the [PRAGMA threads] command) and the amount of content
  2038 ** to be sorted exceeds the page size times the minimum of the
  2039 ** [PRAGMA cache_size] setting and this value.
  2040 ** </dl>
  2041 */
  2042 #define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
  2043 #define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
  2044 #define SQLITE_CONFIG_SERIALIZED    3  /* nil */
  2045 #define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
  2046 #define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
  2047 #define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
  2048 #define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
  2049 #define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
  2050 #define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
  2051 #define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
  2052 #define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
  2053 /* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 
  2054 #define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
  2055 #define SQLITE_CONFIG_PCACHE       14  /* no-op */
  2056 #define SQLITE_CONFIG_GETPCACHE    15  /* no-op */
  2057 #define SQLITE_CONFIG_LOG          16  /* xFunc, void* */
  2058 #define SQLITE_CONFIG_URI          17  /* int */
  2059 #define SQLITE_CONFIG_PCACHE2      18  /* sqlite3_pcache_methods2* */
  2060 #define SQLITE_CONFIG_GETPCACHE2   19  /* sqlite3_pcache_methods2* */
  2061 #define SQLITE_CONFIG_COVERING_INDEX_SCAN 20  /* int */
  2062 #define SQLITE_CONFIG_SQLLOG       21  /* xSqllog, void* */
  2063 #define SQLITE_CONFIG_MMAP_SIZE    22  /* sqlite3_int64, sqlite3_int64 */
  2064 #define SQLITE_CONFIG_WIN32_HEAPSIZE      23  /* int nByte */
  2065 #define SQLITE_CONFIG_PCACHE_HDRSZ        24  /* int *psz */
  2066 #define SQLITE_CONFIG_PMASZ               25  /* unsigned int szPma */
  2067 
  2068 /*
  2069 ** CAPI3REF: Database Connection Configuration Options
  2070 **
  2071 ** These constants are the available integer configuration options that
  2072 ** can be passed as the second argument to the [sqlite3_db_config()] interface.
  2073 **
  2074 ** New configuration options may be added in future releases of SQLite.
  2075 ** Existing configuration options might be discontinued.  Applications
  2076 ** should check the return code from [sqlite3_db_config()] to make sure that
  2077 ** the call worked.  ^The [sqlite3_db_config()] interface will return a
  2078 ** non-zero [error code] if a discontinued or unsupported configuration option
  2079 ** is invoked.
  2080 **
  2081 ** <dl>
  2082 ** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
  2083 ** <dd> ^This option takes three additional arguments that determine the 
  2084 ** [lookaside memory allocator] configuration for the [database connection].
  2085 ** ^The first argument (the third parameter to [sqlite3_db_config()] is a
  2086 ** pointer to a memory buffer to use for lookaside memory.
  2087 ** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
  2088 ** may be NULL in which case SQLite will allocate the
  2089 ** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
  2090 ** size of each lookaside buffer slot.  ^The third argument is the number of
  2091 ** slots.  The size of the buffer in the first argument must be greater than
  2092 ** or equal to the product of the second and third arguments.  The buffer
  2093 ** must be aligned to an 8-byte boundary.  ^If the second argument to
  2094 ** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally
  2095 ** rounded down to the next smaller multiple of 8.  ^(The lookaside memory
  2096 ** configuration for a database connection can only be changed when that
  2097 ** connection is not currently using lookaside memory, or in other words
  2098 ** when the "current value" returned by
  2099 ** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
  2100 ** Any attempt to change the lookaside memory configuration when lookaside
  2101 ** memory is in use leaves the configuration unchanged and returns 
  2102 ** [SQLITE_BUSY].)^</dd>
  2103 **
  2104 ** <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>
  2105 ** <dd> ^This option is used to enable or disable the enforcement of
  2106 ** [foreign key constraints].  There should be two additional arguments.
  2107 ** The first argument is an integer which is 0 to disable FK enforcement,
  2108 ** positive to enable FK enforcement or negative to leave FK enforcement
  2109 ** unchanged.  The second parameter is a pointer to an integer into which
  2110 ** is written 0 or 1 to indicate whether FK enforcement is off or on
  2111 ** following this call.  The second parameter may be a NULL pointer, in
  2112 ** which case the FK enforcement setting is not reported back. </dd>
  2113 **
  2114 ** <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>
  2115 ** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
  2116 ** There should be two additional arguments.
  2117 ** The first argument is an integer which is 0 to disable triggers,
  2118 ** positive to enable triggers or negative to leave the setting unchanged.
  2119 ** The second parameter is a pointer to an integer into which
  2120 ** is written 0 or 1 to indicate whether triggers are disabled or enabled
  2121 ** following this call.  The second parameter may be a NULL pointer, in
  2122 ** which case the trigger setting is not reported back. </dd>
  2123 **
  2124 ** </dl>
  2125 */
  2126 #define SQLITE_DBCONFIG_LOOKASIDE       1001  /* void* int int */
  2127 #define SQLITE_DBCONFIG_ENABLE_FKEY     1002  /* int int* */
  2128 #define SQLITE_DBCONFIG_ENABLE_TRIGGER  1003  /* int int* */
  2129 
  2130 
  2131 /*
  2132 ** CAPI3REF: Enable Or Disable Extended Result Codes
  2133 ** METHOD: sqlite3
  2134 **
  2135 ** ^The sqlite3_extended_result_codes() routine enables or disables the
  2136 ** [extended result codes] feature of SQLite. ^The extended result
  2137 ** codes are disabled by default for historical compatibility.
  2138 */
  2139 SQLITE_API int SQLITE_STDCALL sqlite3_extended_result_codes(sqlite3*, int onoff);
  2140 
  2141 /*
  2142 ** CAPI3REF: Last Insert Rowid
  2143 ** METHOD: sqlite3
  2144 **
  2145 ** ^Each entry in most SQLite tables (except for [WITHOUT ROWID] tables)
  2146 ** has a unique 64-bit signed
  2147 ** integer key called the [ROWID | "rowid"]. ^The rowid is always available
  2148 ** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
  2149 ** names are not also used by explicitly declared columns. ^If
  2150 ** the table has a column of type [INTEGER PRIMARY KEY] then that column
  2151 ** is another alias for the rowid.
  2152 **
  2153 ** ^The sqlite3_last_insert_rowid(D) interface returns the [rowid] of the 
  2154 ** most recent successful [INSERT] into a rowid table or [virtual table]
  2155 ** on database connection D.
  2156 ** ^Inserts into [WITHOUT ROWID] tables are not recorded.
  2157 ** ^If no successful [INSERT]s into rowid tables
  2158 ** have ever occurred on the database connection D, 
  2159 ** then sqlite3_last_insert_rowid(D) returns zero.
  2160 **
  2161 ** ^(If an [INSERT] occurs within a trigger or within a [virtual table]
  2162 ** method, then this routine will return the [rowid] of the inserted
  2163 ** row as long as the trigger or virtual table method is running.
  2164 ** But once the trigger or virtual table method ends, the value returned 
  2165 ** by this routine reverts to what it was before the trigger or virtual
  2166 ** table method began.)^
  2167 **
  2168 ** ^An [INSERT] that fails due to a constraint violation is not a
  2169 ** successful [INSERT] and does not change the value returned by this
  2170 ** routine.  ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
  2171 ** and INSERT OR ABORT make no changes to the return value of this
  2172 ** routine when their insertion fails.  ^(When INSERT OR REPLACE
  2173 ** encounters a constraint violation, it does not fail.  The
  2174 ** INSERT continues to completion after deleting rows that caused
  2175 ** the constraint problem so INSERT OR REPLACE will always change
  2176 ** the return value of this interface.)^
  2177 **
  2178 ** ^For the purposes of this routine, an [INSERT] is considered to
  2179 ** be successful even if it is subsequently rolled back.
  2180 **
  2181 ** This function is accessible to SQL statements via the
  2182 ** [last_insert_rowid() SQL function].
  2183 **
  2184 ** If a separate thread performs a new [INSERT] on the same
  2185 ** database connection while the [sqlite3_last_insert_rowid()]
  2186 ** function is running and thus changes the last insert [rowid],
  2187 ** then the value returned by [sqlite3_last_insert_rowid()] is
  2188 ** unpredictable and might not equal either the old or the new
  2189 ** last insert [rowid].
  2190 */
  2191 SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3_last_insert_rowid(sqlite3*);
  2192 
  2193 /*
  2194 ** CAPI3REF: Count The Number Of Rows Modified
  2195 ** METHOD: sqlite3
  2196 **
  2197 ** ^This function returns the number of rows modified, inserted or
  2198 ** deleted by the most recently completed INSERT, UPDATE or DELETE
  2199 ** statement on the database connection specified by the only parameter.
  2200 ** ^Executing any other type of SQL statement does not modify the value
  2201 ** returned by this function.
  2202 **
  2203 ** ^Only changes made directly by the INSERT, UPDATE or DELETE statement are
  2204 ** considered - auxiliary changes caused by [CREATE TRIGGER | triggers], 
  2205 ** [foreign key actions] or [REPLACE] constraint resolution are not counted.
  2206 ** 
  2207 ** Changes to a view that are intercepted by 
  2208 ** [INSTEAD OF trigger | INSTEAD OF triggers] are not counted. ^The value 
  2209 ** returned by sqlite3_changes() immediately after an INSERT, UPDATE or 
  2210 ** DELETE statement run on a view is always zero. Only changes made to real 
  2211 ** tables are counted.
  2212 **
  2213 ** Things are more complicated if the sqlite3_changes() function is
  2214 ** executed while a trigger program is running. This may happen if the
  2215 ** program uses the [changes() SQL function], or if some other callback
  2216 ** function invokes sqlite3_changes() directly. Essentially:
  2217 ** 
  2218 ** <ul>
  2219 **   <li> ^(Before entering a trigger program the value returned by
  2220 **        sqlite3_changes() function is saved. After the trigger program 
  2221 **        has finished, the original value is restored.)^
  2222 ** 
  2223 **   <li> ^(Within a trigger program each INSERT, UPDATE and DELETE 
  2224 **        statement sets the value returned by sqlite3_changes() 
  2225 **        upon completion as normal. Of course, this value will not include 
  2226 **        any changes performed by sub-triggers, as the sqlite3_changes() 
  2227 **        value will be saved and restored after each sub-trigger has run.)^
  2228 ** </ul>
  2229 ** 
  2230 ** ^This means that if the changes() SQL function (or similar) is used
  2231 ** by the first INSERT, UPDATE or DELETE statement within a trigger, it 
  2232 ** returns the value as set when the calling statement began executing.
  2233 ** ^If it is used by the second or subsequent such statement within a trigger 
  2234 ** program, the value returned reflects the number of rows modified by the 
  2235 ** previous INSERT, UPDATE or DELETE statement within the same trigger.
  2236 **
  2237 ** See also the [sqlite3_total_changes()] interface, the
  2238 ** [count_changes pragma], and the [changes() SQL function].
  2239 **
  2240 ** If a separate thread makes changes on the same database connection
  2241 ** while [sqlite3_changes()] is running then the value returned
  2242 ** is unpredictable and not meaningful.
  2243 */
  2244 SQLITE_API int SQLITE_STDCALL sqlite3_changes(sqlite3*);
  2245 
  2246 /*
  2247 ** CAPI3REF: Total Number Of Rows Modified
  2248 ** METHOD: sqlite3
  2249 **
  2250 ** ^This function returns the total number of rows inserted, modified or
  2251 ** deleted by all [INSERT], [UPDATE] or [DELETE] statements completed
  2252 ** since the database connection was opened, including those executed as
  2253 ** part of trigger programs. ^Executing any other type of SQL statement
  2254 ** does not affect the value returned by sqlite3_total_changes().
  2255 ** 
  2256 ** ^Changes made as part of [foreign key actions] are included in the
  2257 ** count, but those made as part of REPLACE constraint resolution are
  2258 ** not. ^Changes to a view that are intercepted by INSTEAD OF triggers 
  2259 ** are not counted.
  2260 ** 
  2261 ** See also the [sqlite3_changes()] interface, the
  2262 ** [count_changes pragma], and the [total_changes() SQL function].
  2263 **
  2264 ** If a separate thread makes changes on the same database connection
  2265 ** while [sqlite3_total_changes()] is running then the value
  2266 ** returned is unpredictable and not meaningful.
  2267 */
  2268 SQLITE_API int SQLITE_STDCALL sqlite3_total_changes(sqlite3*);
  2269 
  2270 /*
  2271 ** CAPI3REF: Interrupt A Long-Running Query
  2272 ** METHOD: sqlite3
  2273 **
  2274 ** ^This function causes any pending database operation to abort and
  2275 ** return at its earliest opportunity. This routine is typically
  2276 ** called in response to a user action such as pressing "Cancel"
  2277 ** or Ctrl-C where the user wants a long query operation to halt
  2278 ** immediately.
  2279 **
  2280 ** ^It is safe to call this routine from a thread different from the
  2281 ** thread that is currently running the database operation.  But it
  2282 ** is not safe to call this routine with a [database connection] that
  2283 ** is closed or might close before sqlite3_interrupt() returns.
  2284 **
  2285 ** ^If an SQL operation is very nearly finished at the time when
  2286 ** sqlite3_interrupt() is called, then it might not have an opportunity
  2287 ** to be interrupted and might continue to completion.
  2288 **
  2289 ** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
  2290 ** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
  2291 ** that is inside an explicit transaction, then the entire transaction
  2292 ** will be rolled back automatically.
  2293 **
  2294 ** ^The sqlite3_interrupt(D) call is in effect until all currently running
  2295 ** SQL statements on [database connection] D complete.  ^Any new SQL statements
  2296 ** that are started after the sqlite3_interrupt() call and before the 
  2297 ** running statements reaches zero are interrupted as if they had been
  2298 ** running prior to the sqlite3_interrupt() call.  ^New SQL statements
  2299 ** that are started after the running statement count reaches zero are
  2300 ** not effected by the sqlite3_interrupt().
  2301 ** ^A call to sqlite3_interrupt(D) that occurs when there are no running
  2302 ** SQL statements is a no-op and has no effect on SQL statements
  2303 ** that are started after the sqlite3_interrupt() call returns.
  2304 **
  2305 ** If the database connection closes while [sqlite3_interrupt()]
  2306 ** is running then bad things will likely happen.
  2307 */
  2308 SQLITE_API void SQLITE_STDCALL sqlite3_interrupt(sqlite3*);
  2309 
  2310 /*
  2311 ** CAPI3REF: Determine If An SQL Statement Is Complete
  2312 **
  2313 ** These routines are useful during command-line input to determine if the
  2314 ** currently entered text seems to form a complete SQL statement or
  2315 ** if additional input is needed before sending the text into
  2316 ** SQLite for parsing.  ^These routines return 1 if the input string
  2317 ** appears to be a complete SQL statement.  ^A statement is judged to be
  2318 ** complete if it ends with a semicolon token and is not a prefix of a
  2319 ** well-formed CREATE TRIGGER statement.  ^Semicolons that are embedded within
  2320 ** string literals or quoted identifier names or comments are not
  2321 ** independent tokens (they are part of the token in which they are
  2322 ** embedded) and thus do not count as a statement terminator.  ^Whitespace
  2323 ** and comments that follow the final semicolon are ignored.
  2324 **
  2325 ** ^These routines return 0 if the statement is incomplete.  ^If a
  2326 ** memory allocation fails, then SQLITE_NOMEM is returned.
  2327 **
  2328 ** ^These routines do not parse the SQL statements thus
  2329 ** will not detect syntactically incorrect SQL.
  2330 **
  2331 ** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior 
  2332 ** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked
  2333 ** automatically by sqlite3_complete16().  If that initialization fails,
  2334 ** then the return value from sqlite3_complete16() will be non-zero
  2335 ** regardless of whether or not the input SQL is complete.)^
  2336 **
  2337 ** The input to [sqlite3_complete()] must be a zero-terminated
  2338 ** UTF-8 string.
  2339 **
  2340 ** The input to [sqlite3_complete16()] must be a zero-terminated
  2341 ** UTF-16 string in native byte order.
  2342 */
  2343 SQLITE_API int SQLITE_STDCALL sqlite3_complete(const char *sql);
  2344 SQLITE_API int SQLITE_STDCALL sqlite3_complete16(const void *sql);
  2345 
  2346 /*
  2347 ** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
  2348 ** KEYWORDS: {busy-handler callback} {busy handler}
  2349 ** METHOD: sqlite3
  2350 **
  2351 ** ^The sqlite3_busy_handler(D,X,P) routine sets a callback function X
  2352 ** that might be invoked with argument P whenever
  2353 ** an attempt is made to access a database table associated with
  2354 ** [database connection] D when another thread
  2355 ** or process has the table locked.
  2356 ** The sqlite3_busy_handler() interface is used to implement
  2357 ** [sqlite3_busy_timeout()] and [PRAGMA busy_timeout].
  2358 **
  2359 ** ^If the busy callback is NULL, then [SQLITE_BUSY]
  2360 ** is returned immediately upon encountering the lock.  ^If the busy callback
  2361 ** is not NULL, then the callback might be invoked with two arguments.
  2362 **
  2363 ** ^The first argument to the busy handler is a copy of the void* pointer which
  2364 ** is the third argument to sqlite3_busy_handler().  ^The second argument to
  2365 ** the busy handler callback is the number of times that the busy handler has
  2366 ** been invoked previously for the same locking event.  ^If the
  2367 ** busy callback returns 0, then no additional attempts are made to
  2368 ** access the database and [SQLITE_BUSY] is returned
  2369 ** to the application.
  2370 ** ^If the callback returns non-zero, then another attempt
  2371 ** is made to access the database and the cycle repeats.
  2372 **
  2373 ** The presence of a busy handler does not guarantee that it will be invoked
  2374 ** when there is lock contention. ^If SQLite determines that invoking the busy
  2375 ** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
  2376 ** to the application instead of invoking the 
  2377 ** busy handler.
  2378 ** Consider a scenario where one process is holding a read lock that
  2379 ** it is trying to promote to a reserved lock and
  2380 ** a second process is holding a reserved lock that it is trying
  2381 ** to promote to an exclusive lock.  The first process cannot proceed
  2382 ** because it is blocked by the second and the second process cannot
  2383 ** proceed because it is blocked by the first.  If both processes
  2384 ** invoke the busy handlers, neither will make any progress.  Therefore,
  2385 ** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
  2386 ** will induce the first process to release its read lock and allow
  2387 ** the second process to proceed.
  2388 **
  2389 ** ^The default busy callback is NULL.
  2390 **
  2391 ** ^(There can only be a single busy handler defined for each
  2392 ** [database connection].  Setting a new busy handler clears any
  2393 ** previously set handler.)^  ^Note that calling [sqlite3_busy_timeout()]
  2394 ** or evaluating [PRAGMA busy_timeout=N] will change the
  2395 ** busy handler and thus clear any previously set busy handler.
  2396 **
  2397 ** The busy callback should not take any actions which modify the
  2398 ** database connection that invoked the busy handler.  In other words,
  2399 ** the busy handler is not reentrant.  Any such actions
  2400 ** result in undefined behavior.
  2401 ** 
  2402 ** A busy handler must not close the database connection
  2403 ** or [prepared statement] that invoked the busy handler.
  2404 */
  2405 SQLITE_API int SQLITE_STDCALL sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);
  2406 
  2407 /*
  2408 ** CAPI3REF: Set A Busy Timeout
  2409 ** METHOD: sqlite3
  2410 **
  2411 ** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
  2412 ** for a specified amount of time when a table is locked.  ^The handler
  2413 ** will sleep multiple times until at least "ms" milliseconds of sleeping
  2414 ** have accumulated.  ^After at least "ms" milliseconds of sleeping,
  2415 ** the handler returns 0 which causes [sqlite3_step()] to return
  2416 ** [SQLITE_BUSY].
  2417 **
  2418 ** ^Calling this routine with an argument less than or equal to zero
  2419 ** turns off all busy handlers.
  2420 **
  2421 ** ^(There can only be a single busy handler for a particular
  2422 ** [database connection] at any given moment.  If another busy handler
  2423 ** was defined  (using [sqlite3_busy_handler()]) prior to calling
  2424 ** this routine, that other busy handler is cleared.)^
  2425 **
  2426 ** See also:  [PRAGMA busy_timeout]
  2427 */
  2428 SQLITE_API int SQLITE_STDCALL sqlite3_busy_timeout(sqlite3*, int ms);
  2429 
  2430 /*
  2431 ** CAPI3REF: Convenience Routines For Running Queries
  2432 ** METHOD: sqlite3
  2433 **
  2434 ** This is a legacy interface that is preserved for backwards compatibility.
  2435 ** Use of this interface is not recommended.
  2436 **
  2437 ** Definition: A <b>result table</b> is memory data structure created by the
  2438 ** [sqlite3_get_table()] interface.  A result table records the
  2439 ** complete query results from one or more queries.
  2440 **
  2441 ** The table conceptually has a number of rows and columns.  But
  2442 ** these numbers are not part of the result table itself.  These
  2443 ** numbers are obtained separately.  Let N be the number of rows
  2444 ** and M be the number of columns.
  2445 **
  2446 ** A result table is an array of pointers to zero-terminated UTF-8 strings.
  2447 ** There are (N+1)*M elements in the array.  The first M pointers point
  2448 ** to zero-terminated strings that  contain the names of the columns.
  2449 ** The remaining entries all point to query results.  NULL values result
  2450 ** in NULL pointers.  All other values are in their UTF-8 zero-terminated
  2451 ** string representation as returned by [sqlite3_column_text()].
  2452 **
  2453 ** A result table might consist of one or more memory allocations.
  2454 ** It is not safe to pass a result table directly to [sqlite3_free()].
  2455 ** A result table should be deallocated using [sqlite3_free_table()].
  2456 **
  2457 ** ^(As an example of the result table format, suppose a query result
  2458 ** is as follows:
  2459 **
  2460 ** <blockquote><pre>
  2461 **        Name        | Age
  2462 **        -----------------------
  2463 **        Alice       | 43
  2464 **        Bob         | 28
  2465 **        Cindy       | 21
  2466 ** </pre></blockquote>
  2467 **
  2468 ** There are two column (M==2) and three rows (N==3).  Thus the
  2469 ** result table has 8 entries.  Suppose the result table is stored
  2470 ** in an array names azResult.  Then azResult holds this content:
  2471 **
  2472 ** <blockquote><pre>
  2473 **        azResult&#91;0] = "Name";
  2474 **        azResult&#91;1] = "Age";
  2475 **        azResult&#91;2] = "Alice";
  2476 **        azResult&#91;3] = "43";
  2477 **        azResult&#91;4] = "Bob";
  2478 **        azResult&#91;5] = "28";
  2479 **        azResult&#91;6] = "Cindy";
  2480 **        azResult&#91;7] = "21";
  2481 ** </pre></blockquote>)^
  2482 **
  2483 ** ^The sqlite3_get_table() function evaluates one or more
  2484 ** semicolon-separated SQL statements in the zero-terminated UTF-8
  2485 ** string of its 2nd parameter and returns a result table to the
  2486 ** pointer given in its 3rd parameter.
  2487 **
  2488 ** After the application has finished with the result from sqlite3_get_table(),
  2489 ** it must pass the result table pointer to sqlite3_free_table() in order to
  2490 ** release the memory that was malloced.  Because of the way the
  2491 ** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
  2492 ** function must not try to call [sqlite3_free()] directly.  Only
  2493 ** [sqlite3_free_table()] is able to release the memory properly and safely.
  2494 **
  2495 ** The sqlite3_get_table() interface is implemented as a wrapper around
  2496 ** [sqlite3_exec()].  The sqlite3_get_table() routine does not have access
  2497 ** to any internal data structures of SQLite.  It uses only the public
  2498 ** interface defined here.  As a consequence, errors that occur in the
  2499 ** wrapper layer outside of the internal [sqlite3_exec()] call are not
  2500 ** reflected in subsequent calls to [sqlite3_errcode()] or
  2501 ** [sqlite3_errmsg()].
  2502 */
  2503 SQLITE_API int SQLITE_STDCALL sqlite3_get_table(
  2504   sqlite3 *db,          /* An open database */
  2505   const char *zSql,     /* SQL to be evaluated */
  2506   char ***pazResult,    /* Results of the query */
  2507   int *pnRow,           /* Number of result rows written here */
  2508   int *pnColumn,        /* Number of result columns written here */
  2509   char **pzErrmsg       /* Error msg written here */
  2510 );
  2511 SQLITE_API void SQLITE_STDCALL sqlite3_free_table(char **result);
  2512 
  2513 /*
  2514 ** CAPI3REF: Formatted String Printing Functions
  2515 **
  2516 ** These routines are work-alikes of the "printf()" family of functions
  2517 ** from the standard C library.
  2518 ** These routines understand most of the common K&R formatting options,
  2519 ** plus some additional non-standard formats, detailed below.
  2520 ** Note that some of the more obscure formatting options from recent
  2521 ** C-library standards are omitted from this implementation.
  2522 **
  2523 ** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
  2524 ** results into memory obtained from [sqlite3_malloc()].
  2525 ** The strings returned by these two routines should be
  2526 ** released by [sqlite3_free()].  ^Both routines return a
  2527 ** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
  2528 ** memory to hold the resulting string.
  2529 **
  2530 ** ^(The sqlite3_snprintf() routine is similar to "snprintf()" from
  2531 ** the standard C library.  The result is written into the
  2532 ** buffer supplied as the second parameter whose size is given by
  2533 ** the first parameter. Note that the order of the
  2534 ** first two parameters is reversed from snprintf().)^  This is an
  2535 ** historical accident that cannot be fixed without breaking
  2536 ** backwards compatibility.  ^(Note also that sqlite3_snprintf()
  2537 ** returns a pointer to its buffer instead of the number of
  2538 ** characters actually written into the buffer.)^  We admit that
  2539 ** the number of characters written would be a more useful return
  2540 ** value but we cannot change the implementation of sqlite3_snprintf()
  2541 ** now without breaking compatibility.
  2542 **
  2543 ** ^As long as the buffer size is greater than zero, sqlite3_snprintf()
  2544 ** guarantees that the buffer is always zero-terminated.  ^The first
  2545 ** parameter "n" is the total size of the buffer, including space for
  2546 ** the zero terminator.  So the longest string that can be completely
  2547 ** written will be n-1 characters.
  2548 **
  2549 ** ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf().
  2550 **
  2551 ** These routines all implement some additional formatting
  2552 ** options that are useful for constructing SQL statements.
  2553 ** All of the usual printf() formatting options apply.  In addition, there
  2554 ** is are "%q", "%Q", "%w" and "%z" options.
  2555 **
  2556 ** ^(The %q option works like %s in that it substitutes a nul-terminated
  2557 ** string from the argument list.  But %q also doubles every '\'' character.
  2558 ** %q is designed for use inside a string literal.)^  By doubling each '\''
  2559 ** character it escapes that character and allows it to be inserted into
  2560 ** the string.
  2561 **
  2562 ** For example, assume the string variable zText contains text as follows:
  2563 **
  2564 ** <blockquote><pre>
  2565 **  char *zText = "It's a happy day!";
  2566 ** </pre></blockquote>
  2567 **
  2568 ** One can use this text in an SQL statement as follows:
  2569 **
  2570 ** <blockquote><pre>
  2571 **  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);
  2572 **  sqlite3_exec(db, zSQL, 0, 0, 0);
  2573 **  sqlite3_free(zSQL);
  2574 ** </pre></blockquote>
  2575 **
  2576 ** Because the %q format string is used, the '\'' character in zText
  2577 ** is escaped and the SQL generated is as follows:
  2578 **
  2579 ** <blockquote><pre>
  2580 **  INSERT INTO table1 VALUES('It''s a happy day!')
  2581 ** </pre></blockquote>
  2582 **
  2583 ** This is correct.  Had we used %s instead of %q, the generated SQL
  2584 ** would have looked like this:
  2585 **
  2586 ** <blockquote><pre>
  2587 **  INSERT INTO table1 VALUES('It's a happy day!');
  2588 ** </pre></blockquote>
  2589 **
  2590 ** This second example is an SQL syntax error.  As a general rule you should
  2591 ** always use %q instead of %s when inserting text into a string literal.
  2592 **
  2593 ** ^(The %Q option works like %q except it also adds single quotes around
  2594 ** the outside of the total string.  Additionally, if the parameter in the
  2595 ** argument list is a NULL pointer, %Q substitutes the text "NULL" (without
  2596 ** single quotes).)^  So, for example, one could say:
  2597 **
  2598 ** <blockquote><pre>
  2599 **  char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);
  2600 **  sqlite3_exec(db, zSQL, 0, 0, 0);
  2601 **  sqlite3_free(zSQL);
  2602 ** </pre></blockquote>
  2603 **
  2604 ** The code above will render a correct SQL statement in the zSQL
  2605 ** variable even if the zText variable is a NULL pointer.
  2606 **
  2607 ** ^(The "%w" formatting option is like "%q" except that it expects to
  2608 ** be contained within double-quotes instead of single quotes, and it
  2609 ** escapes the double-quote character instead of the single-quote
  2610 ** character.)^  The "%w" formatting option is intended for safely inserting
  2611 ** table and column names into a constructed SQL statement.
  2612 **
  2613 ** ^(The "%z" formatting option works like "%s" but with the
  2614 ** addition that after the string has been read and copied into
  2615 ** the result, [sqlite3_free()] is called on the input string.)^
  2616 */
  2617 SQLITE_API char *SQLITE_CDECL sqlite3_mprintf(const char*,...);
  2618 SQLITE_API char *SQLITE_STDCALL sqlite3_vmprintf(const char*, va_list);
  2619 SQLITE_API char *SQLITE_CDECL sqlite3_snprintf(int,char*,const char*, ...);
  2620 SQLITE_API char *SQLITE_STDCALL sqlite3_vsnprintf(int,char*,const char*, va_list);
  2621 
  2622 /*
  2623 ** CAPI3REF: Memory Allocation Subsystem
  2624 **
  2625 ** The SQLite core uses these three routines for all of its own
  2626 ** internal memory allocation needs. "Core" in the previous sentence
  2627 ** does not include operating-system specific VFS implementation.  The
  2628 ** Windows VFS uses native malloc() and free() for some operations.
  2629 **
  2630 ** ^The sqlite3_malloc() routine returns a pointer to a block
  2631 ** of memory at least N bytes in length, where N is the parameter.
  2632 ** ^If sqlite3_malloc() is unable to obtain sufficient free
  2633 ** memory, it returns a NULL pointer.  ^If the parameter N to
  2634 ** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
  2635 ** a NULL pointer.
  2636 **
  2637 ** ^The sqlite3_malloc64(N) routine works just like
  2638 ** sqlite3_malloc(N) except that N is an unsigned 64-bit integer instead
  2639 ** of a signed 32-bit integer.
  2640 **
  2641 ** ^Calling sqlite3_free() with a pointer previously returned
  2642 ** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
  2643 ** that it might be reused.  ^The sqlite3_free() routine is
  2644 ** a no-op if is called with a NULL pointer.  Passing a NULL pointer
  2645 ** to sqlite3_free() is harmless.  After being freed, memory
  2646 ** should neither be read nor written.  Even reading previously freed
  2647 ** memory might result in a segmentation fault or other severe error.
  2648 ** Memory corruption, a segmentation fault, or other severe error
  2649 ** might result if sqlite3_free() is called with a non-NULL pointer that
  2650 ** was not obtained from sqlite3_malloc() or sqlite3_realloc().
  2651 **
  2652 ** ^The sqlite3_realloc(X,N) interface attempts to resize a
  2653 ** prior memory allocation X to be at least N bytes.
  2654 ** ^If the X parameter to sqlite3_realloc(X,N)
  2655 ** is a NULL pointer then its behavior is identical to calling
  2656 ** sqlite3_malloc(N).
  2657 ** ^If the N parameter to sqlite3_realloc(X,N) is zero or
  2658 ** negative then the behavior is exactly the same as calling
  2659 ** sqlite3_free(X).
  2660 ** ^sqlite3_realloc(X,N) returns a pointer to a memory allocation
  2661 ** of at least N bytes in size or NULL if insufficient memory is available.
  2662 ** ^If M is the size of the prior allocation, then min(N,M) bytes
  2663 ** of the prior allocation are copied into the beginning of buffer returned
  2664 ** by sqlite3_realloc(X,N) and the prior allocation is freed.
  2665 ** ^If sqlite3_realloc(X,N) returns NULL and N is positive, then the
  2666 ** prior allocation is not freed.
  2667 **
  2668 ** ^The sqlite3_realloc64(X,N) interfaces works the same as
  2669 ** sqlite3_realloc(X,N) except that N is a 64-bit unsigned integer instead
  2670 ** of a 32-bit signed integer.
  2671 **
  2672 ** ^If X is a memory allocation previously obtained from sqlite3_malloc(),
  2673 ** sqlite3_malloc64(), sqlite3_realloc(), or sqlite3_realloc64(), then
  2674 ** sqlite3_msize(X) returns the size of that memory allocation in bytes.
  2675 ** ^The value returned by sqlite3_msize(X) might be larger than the number
  2676 ** of bytes requested when X was allocated.  ^If X is a NULL pointer then
  2677 ** sqlite3_msize(X) returns zero.  If X points to something that is not
  2678 ** the beginning of memory allocation, or if it points to a formerly
  2679 ** valid memory allocation that has now been freed, then the behavior
  2680 ** of sqlite3_msize(X) is undefined and possibly harmful.
  2681 **
  2682 ** ^The memory returned by sqlite3_malloc(), sqlite3_realloc(),
  2683 ** sqlite3_malloc64(), and sqlite3_realloc64()
  2684 ** is always aligned to at least an 8 byte boundary, or to a
  2685 ** 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time
  2686 ** option is used.
  2687 **
  2688 ** In SQLite version 3.5.0 and 3.5.1, it was possible to define
  2689 ** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
  2690 ** implementation of these routines to be omitted.  That capability
  2691 ** is no longer provided.  Only built-in memory allocators can be used.
  2692 **
  2693 ** Prior to SQLite version 3.7.10, the Windows OS interface layer called
  2694 ** the system malloc() and free() directly when converting
  2695 ** filenames between the UTF-8 encoding used by SQLite
  2696 ** and whatever filename encoding is used by the particular Windows
  2697 ** installation.  Memory allocation errors were detected, but
  2698 ** they were reported back as [SQLITE_CANTOPEN] or
  2699 ** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
  2700 **
  2701 ** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
  2702 ** must be either NULL or else pointers obtained from a prior
  2703 ** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
  2704 ** not yet been released.
  2705 **
  2706 ** The application must not read or write any part of
  2707 ** a block of memory after it has been released using
  2708 ** [sqlite3_free()] or [sqlite3_realloc()].
  2709 */
  2710 SQLITE_API void *SQLITE_STDCALL sqlite3_malloc(int);
  2711 SQLITE_API void *SQLITE_STDCALL sqlite3_malloc64(sqlite3_uint64);
  2712 SQLITE_API void *SQLITE_STDCALL sqlite3_realloc(void*, int);
  2713 SQLITE_API void *SQLITE_STDCALL sqlite3_realloc64(void*, sqlite3_uint64);
  2714 SQLITE_API void SQLITE_STDCALL sqlite3_free(void*);
  2715 SQLITE_API sqlite3_uint64 SQLITE_STDCALL sqlite3_msize(void*);
  2716 
  2717 /*
  2718 ** CAPI3REF: Memory Allocator Statistics
  2719 **
  2720 ** SQLite provides these two interfaces for reporting on the status
  2721 ** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
  2722 ** routines, which form the built-in memory allocation subsystem.
  2723 **
  2724 ** ^The [sqlite3_memory_used()] routine returns the number of bytes
  2725 ** of memory currently outstanding (malloced but not freed).
  2726 ** ^The [sqlite3_memory_highwater()] routine returns the maximum
  2727 ** value of [sqlite3_memory_used()] since the high-water mark
  2728 ** was last reset.  ^The values returned by [sqlite3_memory_used()] and
  2729 ** [sqlite3_memory_highwater()] include any overhead
  2730 ** added by SQLite in its implementation of [sqlite3_malloc()],
  2731 ** but not overhead added by the any underlying system library
  2732 ** routines that [sqlite3_malloc()] may call.
  2733 **
  2734 ** ^The memory high-water mark is reset to the current value of
  2735 ** [sqlite3_memory_used()] if and only if the parameter to
  2736 ** [sqlite3_memory_highwater()] is true.  ^The value returned
  2737 ** by [sqlite3_memory_highwater(1)] is the high-water mark
  2738 ** prior to the reset.
  2739 */
  2740 SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3_memory_used(void);
  2741 SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3_memory_highwater(int resetFlag);
  2742 
  2743 /*
  2744 ** CAPI3REF: Pseudo-Random Number Generator
  2745 **
  2746 ** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
  2747 ** select random [ROWID | ROWIDs] when inserting new records into a table that
  2748 ** already uses the largest possible [ROWID].  The PRNG is also used for
  2749 ** the build-in random() and randomblob() SQL functions.  This interface allows
  2750 ** applications to access the same PRNG for other purposes.
  2751 **
  2752 ** ^A call to this routine stores N bytes of randomness into buffer P.
  2753 ** ^The P parameter can be a NULL pointer.
  2754 **
  2755 ** ^If this routine has not been previously called or if the previous
  2756 ** call had N less than one or a NULL pointer for P, then the PRNG is
  2757 ** seeded using randomness obtained from the xRandomness method of
  2758 ** the default [sqlite3_vfs] object.
  2759 ** ^If the previous call to this routine had an N of 1 or more and a
  2760 ** non-NULL P then the pseudo-randomness is generated
  2761 ** internally and without recourse to the [sqlite3_vfs] xRandomness
  2762 ** method.
  2763 */
  2764 SQLITE_API void SQLITE_STDCALL sqlite3_randomness(int N, void *P);
  2765 
  2766 /*
  2767 ** CAPI3REF: Compile-Time Authorization Callbacks
  2768 ** METHOD: sqlite3
  2769 **
  2770 ** ^This routine registers an authorizer callback with a particular
  2771 ** [database connection], supplied in the first argument.
  2772 ** ^The authorizer callback is invoked as SQL statements are being compiled
  2773 ** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
  2774 ** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()].  ^At various
  2775 ** points during the compilation process, as logic is being created
  2776 ** to perform various actions, the authorizer callback is invoked to
  2777 ** see if those actions are allowed.  ^The authorizer callback should
  2778 ** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
  2779 ** specific action but allow the SQL statement to continue to be
  2780 ** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
  2781 ** rejected with an error.  ^If the authorizer callback returns
  2782 ** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
  2783 ** then the [sqlite3_prepare_v2()] or equivalent call that triggered
  2784 ** the authorizer will fail with an error message.
  2785 **
  2786 ** When the callback returns [SQLITE_OK], that means the operation
  2787 ** requested is ok.  ^When the callback returns [SQLITE_DENY], the
  2788 ** [sqlite3_prepare_v2()] or equivalent call that triggered the
  2789 ** authorizer will fail with an error message explaining that
  2790 ** access is denied. 
  2791 **
  2792 ** ^The first parameter to the authorizer callback is a copy of the third
  2793 ** parameter to the sqlite3_set_authorizer() interface. ^The second parameter
  2794 ** to the callback is an integer [SQLITE_COPY | action code] that specifies
  2795 ** the particular action to be authorized. ^The third through sixth parameters
  2796 ** to the callback are zero-terminated strings that contain additional
  2797 ** details about the action to be authorized.
  2798 **
  2799 ** ^If the action code is [SQLITE_READ]
  2800 ** and the callback returns [SQLITE_IGNORE] then the
  2801 ** [prepared statement] statement is constructed to substitute
  2802 ** a NULL value in place of the table column that would have
  2803 ** been read if [SQLITE_OK] had been returned.  The [SQLITE_IGNORE]
  2804 ** return can be used to deny an untrusted user access to individual
  2805 ** columns of a table.
  2806 ** ^If the action code is [SQLITE_DELETE] and the callback returns
  2807 ** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the
  2808 ** [truncate optimization] is disabled and all rows are deleted individually.
  2809 **
  2810 ** An authorizer is used when [sqlite3_prepare | preparing]
  2811 ** SQL statements from an untrusted source, to ensure that the SQL statements
  2812 ** do not try to access data they are not allowed to see, or that they do not
  2813 ** try to execute malicious statements that damage the database.  For
  2814 ** example, an application may allow a user to enter arbitrary
  2815 ** SQL queries for evaluation by a database.  But the application does
  2816 ** not want the user to be able to make arbitrary changes to the
  2817 ** database.  An authorizer could then be put in place while the
  2818 ** user-entered SQL is being [sqlite3_prepare | prepared] that
  2819 ** disallows everything except [SELECT] statements.
  2820 **
  2821 ** Applications that need to process SQL from untrusted sources
  2822 ** might also consider lowering resource limits using [sqlite3_limit()]
  2823 ** and limiting database size using the [max_page_count] [PRAGMA]
  2824 ** in addition to using an authorizer.
  2825 **
  2826 ** ^(Only a single authorizer can be in place on a database connection
  2827 ** at a time.  Each call to sqlite3_set_authorizer overrides the
  2828 ** previous call.)^  ^Disable the authorizer by installing a NULL callback.
  2829 ** The authorizer is disabled by default.
  2830 **
  2831 ** The authorizer callback must not do anything that will modify
  2832 ** the database connection that invoked the authorizer callback.
  2833 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  2834 ** database connections for the meaning of "modify" in this paragraph.
  2835 **
  2836 ** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the
  2837 ** statement might be re-prepared during [sqlite3_step()] due to a 
  2838 ** schema change.  Hence, the application should ensure that the
  2839 ** correct authorizer callback remains in place during the [sqlite3_step()].
  2840 **
  2841 ** ^Note that the authorizer callback is invoked only during
  2842 ** [sqlite3_prepare()] or its variants.  Authorization is not
  2843 ** performed during statement evaluation in [sqlite3_step()], unless
  2844 ** as stated in the previous paragraph, sqlite3_step() invokes
  2845 ** sqlite3_prepare_v2() to reprepare a statement after a schema change.
  2846 */
  2847 SQLITE_API int SQLITE_STDCALL sqlite3_set_authorizer(
  2848   sqlite3*,
  2849   int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
  2850   void *pUserData
  2851 );
  2852 
  2853 /*
  2854 ** CAPI3REF: Authorizer Return Codes
  2855 **
  2856 ** The [sqlite3_set_authorizer | authorizer callback function] must
  2857 ** return either [SQLITE_OK] or one of these two constants in order
  2858 ** to signal SQLite whether or not the action is permitted.  See the
  2859 ** [sqlite3_set_authorizer | authorizer documentation] for additional
  2860 ** information.
  2861 **
  2862 ** Note that SQLITE_IGNORE is also used as a [conflict resolution mode]
  2863 ** returned from the [sqlite3_vtab_on_conflict()] interface.
  2864 */
  2865 #define SQLITE_DENY   1   /* Abort the SQL statement with an error */
  2866 #define SQLITE_IGNORE 2   /* Don't allow access, but don't generate an error */
  2867 
  2868 /*
  2869 ** CAPI3REF: Authorizer Action Codes
  2870 **
  2871 ** The [sqlite3_set_authorizer()] interface registers a callback function
  2872 ** that is invoked to authorize certain SQL statement actions.  The
  2873 ** second parameter to the callback is an integer code that specifies
  2874 ** what action is being authorized.  These are the integer action codes that
  2875 ** the authorizer callback may be passed.
  2876 **
  2877 ** These action code values signify what kind of operation is to be
  2878 ** authorized.  The 3rd and 4th parameters to the authorization
  2879 ** callback function will be parameters or NULL depending on which of these
  2880 ** codes is used as the second parameter.  ^(The 5th parameter to the
  2881 ** authorizer callback is the name of the database ("main", "temp",
  2882 ** etc.) if applicable.)^  ^The 6th parameter to the authorizer callback
  2883 ** is the name of the inner-most trigger or view that is responsible for
  2884 ** the access attempt or NULL if this access attempt is directly from
  2885 ** top-level SQL code.
  2886 */
  2887 /******************************************* 3rd ************ 4th ***********/
  2888 #define SQLITE_CREATE_INDEX          1   /* Index Name      Table Name      */
  2889 #define SQLITE_CREATE_TABLE          2   /* Table Name      NULL            */
  2890 #define SQLITE_CREATE_TEMP_INDEX     3   /* Index Name      Table Name      */
  2891 #define SQLITE_CREATE_TEMP_TABLE     4   /* Table Name      NULL            */
  2892 #define SQLITE_CREATE_TEMP_TRIGGER   5   /* Trigger Name    Table Name      */
  2893 #define SQLITE_CREATE_TEMP_VIEW      6   /* View Name       NULL            */
  2894 #define SQLITE_CREATE_TRIGGER        7   /* Trigger Name    Table Name      */
  2895 #define SQLITE_CREATE_VIEW           8   /* View Name       NULL            */
  2896 #define SQLITE_DELETE                9   /* Table Name      NULL            */
  2897 #define SQLITE_DROP_INDEX           10   /* Index Name      Table Name      */
  2898 #define SQLITE_DROP_TABLE           11   /* Table Name      NULL            */
  2899 #define SQLITE_DROP_TEMP_INDEX      12   /* Index Name      Table Name      */
  2900 #define SQLITE_DROP_TEMP_TABLE      13   /* Table Name      NULL            */
  2901 #define SQLITE_DROP_TEMP_TRIGGER    14   /* Trigger Name    Table Name      */
  2902 #define SQLITE_DROP_TEMP_VIEW       15   /* View Name       NULL            */
  2903 #define SQLITE_DROP_TRIGGER         16   /* Trigger Name    Table Name      */
  2904 #define SQLITE_DROP_VIEW            17   /* View Name       NULL            */
  2905 #define SQLITE_INSERT               18   /* Table Name      NULL            */
  2906 #define SQLITE_PRAGMA               19   /* Pragma Name     1st arg or NULL */
  2907 #define SQLITE_READ                 20   /* Table Name      Column Name     */
  2908 #define SQLITE_SELECT               21   /* NULL            NULL            */
  2909 #define SQLITE_TRANSACTION          22   /* Operation       NULL            */
  2910 #define SQLITE_UPDATE               23   /* Table Name      Column Name     */
  2911 #define SQLITE_ATTACH               24   /* Filename        NULL            */
  2912 #define SQLITE_DETACH               25   /* Database Name   NULL            */
  2913 #define SQLITE_ALTER_TABLE          26   /* Database Name   Table Name      */
  2914 #define SQLITE_REINDEX              27   /* Index Name      NULL            */
  2915 #define SQLITE_ANALYZE              28   /* Table Name      NULL            */
  2916 #define SQLITE_CREATE_VTABLE        29   /* Table Name      Module Name     */
  2917 #define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
  2918 #define SQLITE_FUNCTION             31   /* NULL            Function Name   */
  2919 #define SQLITE_SAVEPOINT            32   /* Operation       Savepoint Name  */
  2920 #define SQLITE_COPY                  0   /* No longer used */
  2921 #define SQLITE_RECURSIVE            33   /* NULL            NULL            */
  2922 
  2923 /*
  2924 ** CAPI3REF: Tracing And Profiling Functions
  2925 ** METHOD: sqlite3
  2926 **
  2927 ** These routines register callback functions that can be used for
  2928 ** tracing and profiling the execution of SQL statements.
  2929 **
  2930 ** ^The callback function registered by sqlite3_trace() is invoked at
  2931 ** various times when an SQL statement is being run by [sqlite3_step()].
  2932 ** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
  2933 ** SQL statement text as the statement first begins executing.
  2934 ** ^(Additional sqlite3_trace() callbacks might occur
  2935 ** as each triggered subprogram is entered.  The callbacks for triggers
  2936 ** contain a UTF-8 SQL comment that identifies the trigger.)^
  2937 **
  2938 ** The [SQLITE_TRACE_SIZE_LIMIT] compile-time option can be used to limit
  2939 ** the length of [bound parameter] expansion in the output of sqlite3_trace().
  2940 **
  2941 ** ^The callback function registered by sqlite3_profile() is invoked
  2942 ** as each SQL statement finishes.  ^The profile callback contains
  2943 ** the original statement text and an estimate of wall-clock time
  2944 ** of how long that statement took to run.  ^The profile callback
  2945 ** time is in units of nanoseconds, however the current implementation
  2946 ** is only capable of millisecond resolution so the six least significant
  2947 ** digits in the time are meaningless.  Future versions of SQLite
  2948 ** might provide greater resolution on the profiler callback.  The
  2949 ** sqlite3_profile() function is considered experimental and is
  2950 ** subject to change in future versions of SQLite.
  2951 */
  2952 SQLITE_API void *SQLITE_STDCALL sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*);
  2953 SQLITE_API SQLITE_EXPERIMENTAL void *SQLITE_STDCALL sqlite3_profile(sqlite3*,
  2954    void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
  2955 
  2956 /*
  2957 ** CAPI3REF: Query Progress Callbacks
  2958 ** METHOD: sqlite3
  2959 **
  2960 ** ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback
  2961 ** function X to be invoked periodically during long running calls to
  2962 ** [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for
  2963 ** database connection D.  An example use for this
  2964 ** interface is to keep a GUI updated during a large query.
  2965 **
  2966 ** ^The parameter P is passed through as the only parameter to the 
  2967 ** callback function X.  ^The parameter N is the approximate number of 
  2968 ** [virtual machine instructions] that are evaluated between successive
  2969 ** invocations of the callback X.  ^If N is less than one then the progress
  2970 ** handler is disabled.
  2971 **
  2972 ** ^Only a single progress handler may be defined at one time per
  2973 ** [database connection]; setting a new progress handler cancels the
  2974 ** old one.  ^Setting parameter X to NULL disables the progress handler.
  2975 ** ^The progress handler is also disabled by setting N to a value less
  2976 ** than 1.
  2977 **
  2978 ** ^If the progress callback returns non-zero, the operation is
  2979 ** interrupted.  This feature can be used to implement a
  2980 ** "Cancel" button on a GUI progress dialog box.
  2981 **
  2982 ** The progress handler callback must not do anything that will modify
  2983 ** the database connection that invoked the progress handler.
  2984 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  2985 ** database connections for the meaning of "modify" in this paragraph.
  2986 **
  2987 */
  2988 SQLITE_API void SQLITE_STDCALL sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
  2989 
  2990 /*
  2991 ** CAPI3REF: Opening A New Database Connection
  2992 ** CONSTRUCTOR: sqlite3
  2993 **
  2994 ** ^These routines open an SQLite database file as specified by the 
  2995 ** filename argument. ^The filename argument is interpreted as UTF-8 for
  2996 ** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
  2997 ** order for sqlite3_open16(). ^(A [database connection] handle is usually
  2998 ** returned in *ppDb, even if an error occurs.  The only exception is that
  2999 ** if SQLite is unable to allocate memory to hold the [sqlite3] object,
  3000 ** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
  3001 ** object.)^ ^(If the database is opened (and/or created) successfully, then
  3002 ** [SQLITE_OK] is returned.  Otherwise an [error code] is returned.)^ ^The
  3003 ** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
  3004 ** an English language description of the error following a failure of any
  3005 ** of the sqlite3_open() routines.
  3006 **
  3007 ** ^The default encoding will be UTF-8 for databases created using
  3008 ** sqlite3_open() or sqlite3_open_v2().  ^The default encoding for databases
  3009 ** created using sqlite3_open16() will be UTF-16 in the native byte order.
  3010 **
  3011 ** Whether or not an error occurs when it is opened, resources
  3012 ** associated with the [database connection] handle should be released by
  3013 ** passing it to [sqlite3_close()] when it is no longer required.
  3014 **
  3015 ** The sqlite3_open_v2() interface works like sqlite3_open()
  3016 ** except that it accepts two additional parameters for additional control
  3017 ** over the new database connection.  ^(The flags parameter to
  3018 ** sqlite3_open_v2() can take one of
  3019 ** the following three values, optionally combined with the 
  3020 ** [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE],
  3021 ** [SQLITE_OPEN_PRIVATECACHE], and/or [SQLITE_OPEN_URI] flags:)^
  3022 **
  3023 ** <dl>
  3024 ** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
  3025 ** <dd>The database is opened in read-only mode.  If the database does not
  3026 ** already exist, an error is returned.</dd>)^
  3027 **
  3028 ** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
  3029 ** <dd>The database is opened for reading and writing if possible, or reading
  3030 ** only if the file is write protected by the operating system.  In either
  3031 ** case the database must already exist, otherwise an error is returned.</dd>)^
  3032 **
  3033 ** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
  3034 ** <dd>The database is opened for reading and writing, and is created if
  3035 ** it does not already exist. This is the behavior that is always used for
  3036 ** sqlite3_open() and sqlite3_open16().</dd>)^
  3037 ** </dl>
  3038 **
  3039 ** If the 3rd parameter to sqlite3_open_v2() is not one of the
  3040 ** combinations shown above optionally combined with other
  3041 ** [SQLITE_OPEN_READONLY | SQLITE_OPEN_* bits]
  3042 ** then the behavior is undefined.
  3043 **
  3044 ** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
  3045 ** opens in the multi-thread [threading mode] as long as the single-thread
  3046 ** mode has not been set at compile-time or start-time.  ^If the
  3047 ** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
  3048 ** in the serialized [threading mode] unless single-thread was
  3049 ** previously selected at compile-time or start-time.
  3050 ** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be
  3051 ** eligible to use [shared cache mode], regardless of whether or not shared
  3052 ** cache is enabled using [sqlite3_enable_shared_cache()].  ^The
  3053 ** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not
  3054 ** participate in [shared cache mode] even if it is enabled.
  3055 **
  3056 ** ^The fourth parameter to sqlite3_open_v2() is the name of the
  3057 ** [sqlite3_vfs] object that defines the operating system interface that
  3058 ** the new database connection should use.  ^If the fourth parameter is
  3059 ** a NULL pointer then the default [sqlite3_vfs] object is used.
  3060 **
  3061 ** ^If the filename is ":memory:", then a private, temporary in-memory database
  3062 ** is created for the connection.  ^This in-memory database will vanish when
  3063 ** the database connection is closed.  Future versions of SQLite might
  3064 ** make use of additional special filenames that begin with the ":" character.
  3065 ** It is recommended that when a database filename actually does begin with
  3066 ** a ":" character you should prefix the filename with a pathname such as
  3067 ** "./" to avoid ambiguity.
  3068 **
  3069 ** ^If the filename is an empty string, then a private, temporary
  3070 ** on-disk database will be created.  ^This private database will be
  3071 ** automatically deleted as soon as the database connection is closed.
  3072 **
  3073 ** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
  3074 **
  3075 ** ^If [URI filename] interpretation is enabled, and the filename argument
  3076 ** begins with "file:", then the filename is interpreted as a URI. ^URI
  3077 ** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
  3078 ** set in the fourth argument to sqlite3_open_v2(), or if it has
  3079 ** been enabled globally using the [SQLITE_CONFIG_URI] option with the
  3080 ** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
  3081 ** As of SQLite version 3.7.7, URI filename interpretation is turned off
  3082 ** by default, but future releases of SQLite might enable URI filename
  3083 ** interpretation by default.  See "[URI filenames]" for additional
  3084 ** information.
  3085 **
  3086 ** URI filenames are parsed according to RFC 3986. ^If the URI contains an
  3087 ** authority, then it must be either an empty string or the string 
  3088 ** "localhost". ^If the authority is not an empty string or "localhost", an 
  3089 ** error is returned to the caller. ^The fragment component of a URI, if 
  3090 ** present, is ignored.
  3091 **
  3092 ** ^SQLite uses the path component of the URI as the name of the disk file
  3093 ** which contains the database. ^If the path begins with a '/' character, 
  3094 ** then it is interpreted as an absolute path. ^If the path does not begin 
  3095 ** with a '/' (meaning that the authority section is omitted from the URI)
  3096 ** then the path is interpreted as a relative path. 
  3097 ** ^(On windows, the first component of an absolute path 
  3098 ** is a drive specification (e.g. "C:").)^
  3099 **
  3100 ** [[core URI query parameters]]
  3101 ** The query component of a URI may contain parameters that are interpreted
  3102 ** either by SQLite itself, or by a [VFS | custom VFS implementation].
  3103 ** SQLite and its built-in [VFSes] interpret the
  3104 ** following query parameters:
  3105 **
  3106 ** <ul>
  3107 **   <li> <b>vfs</b>: ^The "vfs" parameter may be used to specify the name of
  3108 **     a VFS object that provides the operating system interface that should
  3109 **     be used to access the database file on disk. ^If this option is set to
  3110 **     an empty string the default VFS object is used. ^Specifying an unknown
  3111 **     VFS is an error. ^If sqlite3_open_v2() is used and the vfs option is
  3112 **     present, then the VFS specified by the option takes precedence over
  3113 **     the value passed as the fourth parameter to sqlite3_open_v2().
  3114 **
  3115 **   <li> <b>mode</b>: ^(The mode parameter may be set to either "ro", "rw",
  3116 **     "rwc", or "memory". Attempting to set it to any other value is
  3117 **     an error)^. 
  3118 **     ^If "ro" is specified, then the database is opened for read-only 
  3119 **     access, just as if the [SQLITE_OPEN_READONLY] flag had been set in the 
  3120 **     third argument to sqlite3_open_v2(). ^If the mode option is set to 
  3121 **     "rw", then the database is opened for read-write (but not create) 
  3122 **     access, as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had 
  3123 **     been set. ^Value "rwc" is equivalent to setting both 
  3124 **     SQLITE_OPEN_READWRITE and SQLITE_OPEN_CREATE.  ^If the mode option is
  3125 **     set to "memory" then a pure [in-memory database] that never reads
  3126 **     or writes from disk is used. ^It is an error to specify a value for
  3127 **     the mode parameter that is less restrictive than that specified by
  3128 **     the flags passed in the third parameter to sqlite3_open_v2().
  3129 **
  3130 **   <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or
  3131 **     "private". ^Setting it to "shared" is equivalent to setting the
  3132 **     SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to
  3133 **     sqlite3_open_v2(). ^Setting the cache parameter to "private" is 
  3134 **     equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit.
  3135 **     ^If sqlite3_open_v2() is used and the "cache" parameter is present in
  3136 **     a URI filename, its value overrides any behavior requested by setting
  3137 **     SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag.
  3138 **
  3139 **  <li> <b>psow</b>: ^The psow parameter indicates whether or not the
  3140 **     [powersafe overwrite] property does or does not apply to the
  3141 **     storage media on which the database file resides.
  3142 **
  3143 **  <li> <b>nolock</b>: ^The nolock parameter is a boolean query parameter
  3144 **     which if set disables file locking in rollback journal modes.  This
  3145 **     is useful for accessing a database on a filesystem that does not
  3146 **     support locking.  Caution:  Database corruption might result if two
  3147 **     or more processes write to the same database and any one of those
  3148 **     processes uses nolock=1.
  3149 **
  3150 **  <li> <b>immutable</b>: ^The immutable parameter is a boolean query
  3151 **     parameter that indicates that the database file is stored on
  3152 **     read-only media.  ^When immutable is set, SQLite assumes that the
  3153 **     database file cannot be changed, even by a process with higher
  3154 **     privilege, and so the database is opened read-only and all locking
  3155 **     and change detection is disabled.  Caution: Setting the immutable
  3156 **     property on a database file that does in fact change can result
  3157 **     in incorrect query results and/or [SQLITE_CORRUPT] errors.
  3158 **     See also: [SQLITE_IOCAP_IMMUTABLE].
  3159 **       
  3160 ** </ul>
  3161 **
  3162 ** ^Specifying an unknown parameter in the query component of a URI is not an
  3163 ** error.  Future versions of SQLite might understand additional query
  3164 ** parameters.  See "[query parameters with special meaning to SQLite]" for
  3165 ** additional information.
  3166 **
  3167 ** [[URI filename examples]] <h3>URI filename examples</h3>
  3168 **
  3169 ** <table border="1" align=center cellpadding=5>
  3170 ** <tr><th> URI filenames <th> Results
  3171 ** <tr><td> file:data.db <td> 
  3172 **          Open the file "data.db" in the current directory.
  3173 ** <tr><td> file:/home/fred/data.db<br>
  3174 **          file:///home/fred/data.db <br> 
  3175 **          file://localhost/home/fred/data.db <br> <td> 
  3176 **          Open the database file "/home/fred/data.db".
  3177 ** <tr><td> file://darkstar/home/fred/data.db <td> 
  3178 **          An error. "darkstar" is not a recognized authority.
  3179 ** <tr><td style="white-space:nowrap"> 
  3180 **          file:///C:/Documents%20and%20Settings/fred/Desktop/data.db
  3181 **     <td> Windows only: Open the file "data.db" on fred's desktop on drive
  3182 **          C:. Note that the %20 escaping in this example is not strictly 
  3183 **          necessary - space characters can be used literally
  3184 **          in URI filenames.
  3185 ** <tr><td> file:data.db?mode=ro&cache=private <td> 
  3186 **          Open file "data.db" in the current directory for read-only access.
  3187 **          Regardless of whether or not shared-cache mode is enabled by
  3188 **          default, use a private cache.
  3189 ** <tr><td> file:/home/fred/data.db?vfs=unix-dotfile <td>
  3190 **          Open file "/home/fred/data.db". Use the special VFS "unix-dotfile"
  3191 **          that uses dot-files in place of posix advisory locking.
  3192 ** <tr><td> file:data.db?mode=readonly <td> 
  3193 **          An error. "readonly" is not a valid option for the "mode" parameter.
  3194 ** </table>
  3195 **
  3196 ** ^URI hexadecimal escape sequences (%HH) are supported within the path and
  3197 ** query components of a URI. A hexadecimal escape sequence consists of a
  3198 ** percent sign - "%" - followed by exactly two hexadecimal digits 
  3199 ** specifying an octet value. ^Before the path or query components of a
  3200 ** URI filename are interpreted, they are encoded using UTF-8 and all 
  3201 ** hexadecimal escape sequences replaced by a single byte containing the
  3202 ** corresponding octet. If this process generates an invalid UTF-8 encoding,
  3203 ** the results are undefined.
  3204 **
  3205 ** <b>Note to Windows users:</b>  The encoding used for the filename argument
  3206 ** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
  3207 ** codepage is currently defined.  Filenames containing international
  3208 ** characters must be converted to UTF-8 prior to passing them into
  3209 ** sqlite3_open() or sqlite3_open_v2().
  3210 **
  3211 ** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
  3212 ** prior to calling sqlite3_open() or sqlite3_open_v2().  Otherwise, various
  3213 ** features that require the use of temporary files may fail.
  3214 **
  3215 ** See also: [sqlite3_temp_directory]
  3216 */
  3217 SQLITE_API int SQLITE_STDCALL sqlite3_open(
  3218   const char *filename,   /* Database filename (UTF-8) */
  3219   sqlite3 **ppDb          /* OUT: SQLite db handle */
  3220 );
  3221 SQLITE_API int SQLITE_STDCALL sqlite3_open16(
  3222   const void *filename,   /* Database filename (UTF-16) */
  3223   sqlite3 **ppDb          /* OUT: SQLite db handle */
  3224 );
  3225 SQLITE_API int SQLITE_STDCALL sqlite3_open_v2(
  3226   const char *filename,   /* Database filename (UTF-8) */
  3227   sqlite3 **ppDb,         /* OUT: SQLite db handle */
  3228   int flags,              /* Flags */
  3229   const char *zVfs        /* Name of VFS module to use */
  3230 );
  3231 
  3232 /*
  3233 ** CAPI3REF: Obtain Values For URI Parameters
  3234 **
  3235 ** These are utility routines, useful to VFS implementations, that check
  3236 ** to see if a database file was a URI that contained a specific query 
  3237 ** parameter, and if so obtains the value of that query parameter.
  3238 **
  3239 ** If F is the database filename pointer passed into the xOpen() method of 
  3240 ** a VFS implementation when the flags parameter to xOpen() has one or 
  3241 ** more of the [SQLITE_OPEN_URI] or [SQLITE_OPEN_MAIN_DB] bits set and
  3242 ** P is the name of the query parameter, then
  3243 ** sqlite3_uri_parameter(F,P) returns the value of the P
  3244 ** parameter if it exists or a NULL pointer if P does not appear as a 
  3245 ** query parameter on F.  If P is a query parameter of F
  3246 ** has no explicit value, then sqlite3_uri_parameter(F,P) returns
  3247 ** a pointer to an empty string.
  3248 **
  3249 ** The sqlite3_uri_boolean(F,P,B) routine assumes that P is a boolean
  3250 ** parameter and returns true (1) or false (0) according to the value
  3251 ** of P.  The sqlite3_uri_boolean(F,P,B) routine returns true (1) if the
  3252 ** value of query parameter P is one of "yes", "true", or "on" in any
  3253 ** case or if the value begins with a non-zero number.  The 
  3254 ** sqlite3_uri_boolean(F,P,B) routines returns false (0) if the value of
  3255 ** query parameter P is one of "no", "false", or "off" in any case or
  3256 ** if the value begins with a numeric zero.  If P is not a query
  3257 ** parameter on F or if the value of P is does not match any of the
  3258 ** above, then sqlite3_uri_boolean(F,P,B) returns (B!=0).
  3259 **
  3260 ** The sqlite3_uri_int64(F,P,D) routine converts the value of P into a
  3261 ** 64-bit signed integer and returns that integer, or D if P does not
  3262 ** exist.  If the value of P is something other than an integer, then
  3263 ** zero is returned.
  3264 ** 
  3265 ** If F is a NULL pointer, then sqlite3_uri_parameter(F,P) returns NULL and
  3266 ** sqlite3_uri_boolean(F,P,B) returns B.  If F is not a NULL pointer and
  3267 ** is not a database file pathname pointer that SQLite passed into the xOpen
  3268 ** VFS method, then the behavior of this routine is undefined and probably
  3269 ** undesirable.
  3270 */
  3271 SQLITE_API const char *SQLITE_STDCALL sqlite3_uri_parameter(const char *zFilename, const char *zParam);
  3272 SQLITE_API int SQLITE_STDCALL sqlite3_uri_boolean(const char *zFile, const char *zParam, int bDefault);
  3273 SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3_uri_int64(const char*, const char*, sqlite3_int64);
  3274 
  3275 
  3276 /*
  3277 ** CAPI3REF: Error Codes And Messages
  3278 ** METHOD: sqlite3
  3279 **
  3280 ** ^If the most recent sqlite3_* API call associated with 
  3281 ** [database connection] D failed, then the sqlite3_errcode(D) interface
  3282 ** returns the numeric [result code] or [extended result code] for that
  3283 ** API call.
  3284 ** If the most recent API call was successful,
  3285 ** then the return value from sqlite3_errcode() is undefined.
  3286 ** ^The sqlite3_extended_errcode()
  3287 ** interface is the same except that it always returns the 
  3288 ** [extended result code] even when extended result codes are
  3289 ** disabled.
  3290 **
  3291 ** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
  3292 ** text that describes the error, as either UTF-8 or UTF-16 respectively.
  3293 ** ^(Memory to hold the error message string is managed internally.
  3294 ** The application does not need to worry about freeing the result.
  3295 ** However, the error string might be overwritten or deallocated by
  3296 ** subsequent calls to other SQLite interface functions.)^
  3297 **
  3298 ** ^The sqlite3_errstr() interface returns the English-language text
  3299 ** that describes the [result code], as UTF-8.
  3300 ** ^(Memory to hold the error message string is managed internally
  3301 ** and must not be freed by the application)^.
  3302 **
  3303 ** When the serialized [threading mode] is in use, it might be the
  3304 ** case that a second error occurs on a separate thread in between
  3305 ** the time of the first error and the call to these interfaces.
  3306 ** When that happens, the second error will be reported since these
  3307 ** interfaces always report the most recent result.  To avoid
  3308 ** this, each thread can obtain exclusive use of the [database connection] D
  3309 ** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
  3310 ** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
  3311 ** all calls to the interfaces listed here are completed.
  3312 **
  3313 ** If an interface fails with SQLITE_MISUSE, that means the interface
  3314 ** was invoked incorrectly by the application.  In that case, the
  3315 ** error code and message may or may not be set.
  3316 */
  3317 SQLITE_API int SQLITE_STDCALL sqlite3_errcode(sqlite3 *db);
  3318 SQLITE_API int SQLITE_STDCALL sqlite3_extended_errcode(sqlite3 *db);
  3319 SQLITE_API const char *SQLITE_STDCALL sqlite3_errmsg(sqlite3*);
  3320 SQLITE_API const void *SQLITE_STDCALL sqlite3_errmsg16(sqlite3*);
  3321 SQLITE_API const char *SQLITE_STDCALL sqlite3_errstr(int);
  3322 
  3323 /*
  3324 ** CAPI3REF: Prepared Statement Object
  3325 ** KEYWORDS: {prepared statement} {prepared statements}
  3326 **
  3327 ** An instance of this object represents a single SQL statement that
  3328 ** has been compiled into binary form and is ready to be evaluated.
  3329 **
  3330 ** Think of each SQL statement as a separate computer program.  The
  3331 ** original SQL text is source code.  A prepared statement object 
  3332 ** is the compiled object code.  All SQL must be converted into a
  3333 ** prepared statement before it can be run.
  3334 **
  3335 ** The life-cycle of a prepared statement object usually goes like this:
  3336 **
  3337 ** <ol>
  3338 ** <li> Create the prepared statement object using [sqlite3_prepare_v2()].
  3339 ** <li> Bind values to [parameters] using the sqlite3_bind_*()
  3340 **      interfaces.
  3341 ** <li> Run the SQL by calling [sqlite3_step()] one or more times.
  3342 ** <li> Reset the prepared statement using [sqlite3_reset()] then go back
  3343 **      to step 2.  Do this zero or more times.
  3344 ** <li> Destroy the object using [sqlite3_finalize()].
  3345 ** </ol>
  3346 */
  3347 typedef struct sqlite3_stmt sqlite3_stmt;
  3348 
  3349 /*
  3350 ** CAPI3REF: Run-time Limits
  3351 ** METHOD: sqlite3
  3352 **
  3353 ** ^(This interface allows the size of various constructs to be limited
  3354 ** on a connection by connection basis.  The first parameter is the
  3355 ** [database connection] whose limit is to be set or queried.  The
  3356 ** second parameter is one of the [limit categories] that define a
  3357 ** class of constructs to be size limited.  The third parameter is the
  3358 ** new limit for that construct.)^
  3359 **
  3360 ** ^If the new limit is a negative number, the limit is unchanged.
  3361 ** ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a 
  3362 ** [limits | hard upper bound]
  3363 ** set at compile-time by a C preprocessor macro called
  3364 ** [limits | SQLITE_MAX_<i>NAME</i>].
  3365 ** (The "_LIMIT_" in the name is changed to "_MAX_".))^
  3366 ** ^Attempts to increase a limit above its hard upper bound are
  3367 ** silently truncated to the hard upper bound.
  3368 **
  3369 ** ^Regardless of whether or not the limit was changed, the 
  3370 ** [sqlite3_limit()] interface returns the prior value of the limit.
  3371 ** ^Hence, to find the current value of a limit without changing it,
  3372 ** simply invoke this interface with the third parameter set to -1.
  3373 **
  3374 ** Run-time limits are intended for use in applications that manage
  3375 ** both their own internal database and also databases that are controlled
  3376 ** by untrusted external sources.  An example application might be a
  3377 ** web browser that has its own databases for storing history and
  3378 ** separate databases controlled by JavaScript applications downloaded
  3379 ** off the Internet.  The internal databases can be given the
  3380 ** large, default limits.  Databases managed by external sources can
  3381 ** be given much smaller limits designed to prevent a denial of service
  3382 ** attack.  Developers might also want to use the [sqlite3_set_authorizer()]
  3383 ** interface to further control untrusted SQL.  The size of the database
  3384 ** created by an untrusted script can be contained using the
  3385 ** [max_page_count] [PRAGMA].
  3386 **
  3387 ** New run-time limit categories may be added in future releases.
  3388 */
  3389 SQLITE_API int SQLITE_STDCALL sqlite3_limit(sqlite3*, int id, int newVal);
  3390 
  3391 /*
  3392 ** CAPI3REF: Run-Time Limit Categories
  3393 ** KEYWORDS: {limit category} {*limit categories}
  3394 **
  3395 ** These constants define various performance limits
  3396 ** that can be lowered at run-time using [sqlite3_limit()].
  3397 ** The synopsis of the meanings of the various limits is shown below.
  3398 ** Additional information is available at [limits | Limits in SQLite].
  3399 **
  3400 ** <dl>
  3401 ** [[SQLITE_LIMIT_LENGTH]] ^(<dt>SQLITE_LIMIT_LENGTH</dt>
  3402 ** <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^
  3403 **
  3404 ** [[SQLITE_LIMIT_SQL_LENGTH]] ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt>
  3405 ** <dd>The maximum length of an SQL statement, in bytes.</dd>)^
  3406 **
  3407 ** [[SQLITE_LIMIT_COLUMN]] ^(<dt>SQLITE_LIMIT_COLUMN</dt>
  3408 ** <dd>The maximum number of columns in a table definition or in the
  3409 ** result set of a [SELECT] or the maximum number of columns in an index
  3410 ** or in an ORDER BY or GROUP BY clause.</dd>)^
  3411 **
  3412 ** [[SQLITE_LIMIT_EXPR_DEPTH]] ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
  3413 ** <dd>The maximum depth of the parse tree on any expression.</dd>)^
  3414 **
  3415 ** [[SQLITE_LIMIT_COMPOUND_SELECT]] ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
  3416 ** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^
  3417 **
  3418 ** [[SQLITE_LIMIT_VDBE_OP]] ^(<dt>SQLITE_LIMIT_VDBE_OP</dt>
  3419 ** <dd>The maximum number of instructions in a virtual machine program
  3420 ** used to implement an SQL statement.  This limit is not currently
  3421 ** enforced, though that might be added in some future release of
  3422 ** SQLite.</dd>)^
  3423 **
  3424 ** [[SQLITE_LIMIT_FUNCTION_ARG]] ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
  3425 ** <dd>The maximum number of arguments on a function.</dd>)^
  3426 **
  3427 ** [[SQLITE_LIMIT_ATTACHED]] ^(<dt>SQLITE_LIMIT_ATTACHED</dt>
  3428 ** <dd>The maximum number of [ATTACH | attached databases].)^</dd>
  3429 **
  3430 ** [[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]]
  3431 ** ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
  3432 ** <dd>The maximum length of the pattern argument to the [LIKE] or
  3433 ** [GLOB] operators.</dd>)^
  3434 **
  3435 ** [[SQLITE_LIMIT_VARIABLE_NUMBER]]
  3436 ** ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
  3437 ** <dd>The maximum index number of any [parameter] in an SQL statement.)^
  3438 **
  3439 ** [[SQLITE_LIMIT_TRIGGER_DEPTH]] ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt>
  3440 ** <dd>The maximum depth of recursion for triggers.</dd>)^
  3441 **
  3442 ** [[SQLITE_LIMIT_WORKER_THREADS]] ^(<dt>SQLITE_LIMIT_WORKER_THREADS</dt>
  3443 ** <dd>The maximum number of auxiliary worker threads that a single
  3444 ** [prepared statement] may start.</dd>)^
  3445 ** </dl>
  3446 */
  3447 #define SQLITE_LIMIT_LENGTH                    0
  3448 #define SQLITE_LIMIT_SQL_LENGTH                1
  3449 #define SQLITE_LIMIT_COLUMN                    2
  3450 #define SQLITE_LIMIT_EXPR_DEPTH                3
  3451 #define SQLITE_LIMIT_COMPOUND_SELECT           4
  3452 #define SQLITE_LIMIT_VDBE_OP                   5
  3453 #define SQLITE_LIMIT_FUNCTION_ARG              6
  3454 #define SQLITE_LIMIT_ATTACHED                  7
  3455 #define SQLITE_LIMIT_LIKE_PATTERN_LENGTH       8
  3456 #define SQLITE_LIMIT_VARIABLE_NUMBER           9
  3457 #define SQLITE_LIMIT_TRIGGER_DEPTH            10
  3458 #define SQLITE_LIMIT_WORKER_THREADS           11
  3459 
  3460 /*
  3461 ** CAPI3REF: Compiling An SQL Statement
  3462 ** KEYWORDS: {SQL statement compiler}
  3463 ** METHOD: sqlite3
  3464 ** CONSTRUCTOR: sqlite3_stmt
  3465 **
  3466 ** To execute an SQL query, it must first be compiled into a byte-code
  3467 ** program using one of these routines.
  3468 **
  3469 ** The first argument, "db", is a [database connection] obtained from a
  3470 ** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or
  3471 ** [sqlite3_open16()].  The database connection must not have been closed.
  3472 **
  3473 ** The second argument, "zSql", is the statement to be compiled, encoded
  3474 ** as either UTF-8 or UTF-16.  The sqlite3_prepare() and sqlite3_prepare_v2()
  3475 ** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()
  3476 ** use UTF-16.
  3477 **
  3478 ** ^If the nByte argument is negative, then zSql is read up to the
  3479 ** first zero terminator. ^If nByte is positive, then it is the
  3480 ** number of bytes read from zSql.  ^If nByte is zero, then no prepared
  3481 ** statement is generated.
  3482 ** If the caller knows that the supplied string is nul-terminated, then
  3483 ** there is a small performance advantage to passing an nByte parameter that
  3484 ** is the number of bytes in the input string <i>including</i>
  3485 ** the nul-terminator.
  3486 **
  3487 ** ^If pzTail is not NULL then *pzTail is made to point to the first byte
  3488 ** past the end of the first SQL statement in zSql.  These routines only
  3489 ** compile the first statement in zSql, so *pzTail is left pointing to
  3490 ** what remains uncompiled.
  3491 **
  3492 ** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
  3493 ** executed using [sqlite3_step()].  ^If there is an error, *ppStmt is set
  3494 ** to NULL.  ^If the input text contains no SQL (if the input is an empty
  3495 ** string or a comment) then *ppStmt is set to NULL.
  3496 ** The calling procedure is responsible for deleting the compiled
  3497 ** SQL statement using [sqlite3_finalize()] after it has finished with it.
  3498 ** ppStmt may not be NULL.
  3499 **
  3500 ** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK];
  3501 ** otherwise an [error code] is returned.
  3502 **
  3503 ** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are
  3504 ** recommended for all new programs. The two older interfaces are retained
  3505 ** for backwards compatibility, but their use is discouraged.
  3506 ** ^In the "v2" interfaces, the prepared statement
  3507 ** that is returned (the [sqlite3_stmt] object) contains a copy of the
  3508 ** original SQL text. This causes the [sqlite3_step()] interface to
  3509 ** behave differently in three ways:
  3510 **
  3511 ** <ol>
  3512 ** <li>
  3513 ** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
  3514 ** always used to do, [sqlite3_step()] will automatically recompile the SQL
  3515 ** statement and try to run it again. As many as [SQLITE_MAX_SCHEMA_RETRY]
  3516 ** retries will occur before sqlite3_step() gives up and returns an error.
  3517 ** </li>
  3518 **
  3519 ** <li>
  3520 ** ^When an error occurs, [sqlite3_step()] will return one of the detailed
  3521 ** [error codes] or [extended error codes].  ^The legacy behavior was that
  3522 ** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
  3523 ** and the application would have to make a second call to [sqlite3_reset()]
  3524 ** in order to find the underlying cause of the problem. With the "v2" prepare
  3525 ** interfaces, the underlying reason for the error is returned immediately.
  3526 ** </li>
  3527 **
  3528 ** <li>
  3529 ** ^If the specific value bound to [parameter | host parameter] in the 
  3530 ** WHERE clause might influence the choice of query plan for a statement,
  3531 ** then the statement will be automatically recompiled, as if there had been 
  3532 ** a schema change, on the first  [sqlite3_step()] call following any change
  3533 ** to the [sqlite3_bind_text | bindings] of that [parameter]. 
  3534 ** ^The specific value of WHERE-clause [parameter] might influence the 
  3535 ** choice of query plan if the parameter is the left-hand side of a [LIKE]
  3536 ** or [GLOB] operator or if the parameter is compared to an indexed column
  3537 ** and the [SQLITE_ENABLE_STAT3] compile-time option is enabled.
  3538 ** </li>
  3539 ** </ol>
  3540 */
  3541 SQLITE_API int SQLITE_STDCALL sqlite3_prepare(
  3542   sqlite3 *db,            /* Database handle */
  3543   const char *zSql,       /* SQL statement, UTF-8 encoded */
  3544   int nByte,              /* Maximum length of zSql in bytes. */
  3545   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3546   const char **pzTail     /* OUT: Pointer to unused portion of zSql */
  3547 );
  3548 SQLITE_API int SQLITE_STDCALL sqlite3_prepare_v2(
  3549   sqlite3 *db,            /* Database handle */
  3550   const char *zSql,       /* SQL statement, UTF-8 encoded */
  3551   int nByte,              /* Maximum length of zSql in bytes. */
  3552   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3553   const char **pzTail     /* OUT: Pointer to unused portion of zSql */
  3554 );
  3555 SQLITE_API int SQLITE_STDCALL sqlite3_prepare16(
  3556   sqlite3 *db,            /* Database handle */
  3557   const void *zSql,       /* SQL statement, UTF-16 encoded */
  3558   int nByte,              /* Maximum length of zSql in bytes. */
  3559   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3560   const void **pzTail     /* OUT: Pointer to unused portion of zSql */
  3561 );
  3562 SQLITE_API int SQLITE_STDCALL sqlite3_prepare16_v2(
  3563   sqlite3 *db,            /* Database handle */
  3564   const void *zSql,       /* SQL statement, UTF-16 encoded */
  3565   int nByte,              /* Maximum length of zSql in bytes. */
  3566   sqlite3_stmt **ppStmt,  /* OUT: Statement handle */
  3567   const void **pzTail     /* OUT: Pointer to unused portion of zSql */
  3568 );
  3569 
  3570 /*
  3571 ** CAPI3REF: Retrieving Statement SQL
  3572 ** METHOD: sqlite3_stmt
  3573 **
  3574 ** ^This interface can be used to retrieve a saved copy of the original
  3575 ** SQL text used to create a [prepared statement] if that statement was
  3576 ** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
  3577 */
  3578 SQLITE_API const char *SQLITE_STDCALL sqlite3_sql(sqlite3_stmt *pStmt);
  3579 
  3580 /*
  3581 ** CAPI3REF: Determine If An SQL Statement Writes The Database
  3582 ** METHOD: sqlite3_stmt
  3583 **
  3584 ** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if
  3585 ** and only if the [prepared statement] X makes no direct changes to
  3586 ** the content of the database file.
  3587 **
  3588 ** Note that [application-defined SQL functions] or
  3589 ** [virtual tables] might change the database indirectly as a side effect.  
  3590 ** ^(For example, if an application defines a function "eval()" that 
  3591 ** calls [sqlite3_exec()], then the following SQL statement would
  3592 ** change the database file through side-effects:
  3593 **
  3594 ** <blockquote><pre>
  3595 **    SELECT eval('DELETE FROM t1') FROM t2;
  3596 ** </pre></blockquote>
  3597 **
  3598 ** But because the [SELECT] statement does not change the database file
  3599 ** directly, sqlite3_stmt_readonly() would still return true.)^
  3600 **
  3601 ** ^Transaction control statements such as [BEGIN], [COMMIT], [ROLLBACK],
  3602 ** [SAVEPOINT], and [RELEASE] cause sqlite3_stmt_readonly() to return true,
  3603 ** since the statements themselves do not actually modify the database but
  3604 ** rather they control the timing of when other statements modify the 
  3605 ** database.  ^The [ATTACH] and [DETACH] statements also cause
  3606 ** sqlite3_stmt_readonly() to return true since, while those statements
  3607 ** change the configuration of a database connection, they do not make 
  3608 ** changes to the content of the database files on disk.
  3609 */
  3610 SQLITE_API int SQLITE_STDCALL sqlite3_stmt_readonly(sqlite3_stmt *pStmt);
  3611 
  3612 /*
  3613 ** CAPI3REF: Determine If A Prepared Statement Has Been Reset
  3614 ** METHOD: sqlite3_stmt
  3615 **
  3616 ** ^The sqlite3_stmt_busy(S) interface returns true (non-zero) if the
  3617 ** [prepared statement] S has been stepped at least once using 
  3618 ** [sqlite3_step(S)] but has neither run to completion (returned
  3619 ** [SQLITE_DONE] from [sqlite3_step(S)]) nor
  3620 ** been reset using [sqlite3_reset(S)].  ^The sqlite3_stmt_busy(S)
  3621 ** interface returns false if S is a NULL pointer.  If S is not a 
  3622 ** NULL pointer and is not a pointer to a valid [prepared statement]
  3623 ** object, then the behavior is undefined and probably undesirable.
  3624 **
  3625 ** This interface can be used in combination [sqlite3_next_stmt()]
  3626 ** to locate all prepared statements associated with a database 
  3627 ** connection that are in need of being reset.  This can be used,
  3628 ** for example, in diagnostic routines to search for prepared 
  3629 ** statements that are holding a transaction open.
  3630 */
  3631 SQLITE_API int SQLITE_STDCALL sqlite3_stmt_busy(sqlite3_stmt*);
  3632 
  3633 /*
  3634 ** CAPI3REF: Dynamically Typed Value Object
  3635 ** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
  3636 **
  3637 ** SQLite uses the sqlite3_value object to represent all values
  3638 ** that can be stored in a database table. SQLite uses dynamic typing
  3639 ** for the values it stores.  ^Values stored in sqlite3_value objects
  3640 ** can be integers, floating point values, strings, BLOBs, or NULL.
  3641 **
  3642 ** An sqlite3_value object may be either "protected" or "unprotected".
  3643 ** Some interfaces require a protected sqlite3_value.  Other interfaces
  3644 ** will accept either a protected or an unprotected sqlite3_value.
  3645 ** Every interface that accepts sqlite3_value arguments specifies
  3646 ** whether or not it requires a protected sqlite3_value.  The
  3647 ** [sqlite3_value_dup()] interface can be used to construct a new 
  3648 ** protected sqlite3_value from an unprotected sqlite3_value.
  3649 **
  3650 ** The terms "protected" and "unprotected" refer to whether or not
  3651 ** a mutex is held.  An internal mutex is held for a protected
  3652 ** sqlite3_value object but no mutex is held for an unprotected
  3653 ** sqlite3_value object.  If SQLite is compiled to be single-threaded
  3654 ** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
  3655 ** or if SQLite is run in one of reduced mutex modes 
  3656 ** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
  3657 ** then there is no distinction between protected and unprotected
  3658 ** sqlite3_value objects and they can be used interchangeably.  However,
  3659 ** for maximum code portability it is recommended that applications
  3660 ** still make the distinction between protected and unprotected
  3661 ** sqlite3_value objects even when not strictly required.
  3662 **
  3663 ** ^The sqlite3_value objects that are passed as parameters into the
  3664 ** implementation of [application-defined SQL functions] are protected.
  3665 ** ^The sqlite3_value object returned by
  3666 ** [sqlite3_column_value()] is unprotected.
  3667 ** Unprotected sqlite3_value objects may only be used with
  3668 ** [sqlite3_result_value()] and [sqlite3_bind_value()].
  3669 ** The [sqlite3_value_blob | sqlite3_value_type()] family of
  3670 ** interfaces require protected sqlite3_value objects.
  3671 */
  3672 typedef struct Mem sqlite3_value;
  3673 
  3674 /*
  3675 ** CAPI3REF: SQL Function Context Object
  3676 **
  3677 ** The context in which an SQL function executes is stored in an
  3678 ** sqlite3_context object.  ^A pointer to an sqlite3_context object
  3679 ** is always first parameter to [application-defined SQL functions].
  3680 ** The application-defined SQL function implementation will pass this
  3681 ** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
  3682 ** [sqlite3_aggregate_context()], [sqlite3_user_data()],
  3683 ** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
  3684 ** and/or [sqlite3_set_auxdata()].
  3685 */
  3686 typedef struct sqlite3_context sqlite3_context;
  3687 
  3688 /*
  3689 ** CAPI3REF: Binding Values To Prepared Statements
  3690 ** KEYWORDS: {host parameter} {host parameters} {host parameter name}
  3691 ** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
  3692 ** METHOD: sqlite3_stmt
  3693 **
  3694 ** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants,
  3695 ** literals may be replaced by a [parameter] that matches one of following
  3696 ** templates:
  3697 **
  3698 ** <ul>
  3699 ** <li>  ?
  3700 ** <li>  ?NNN
  3701 ** <li>  :VVV
  3702 ** <li>  @VVV
  3703 ** <li>  $VVV
  3704 ** </ul>
  3705 **
  3706 ** In the templates above, NNN represents an integer literal,
  3707 ** and VVV represents an alphanumeric identifier.)^  ^The values of these
  3708 ** parameters (also called "host parameter names" or "SQL parameters")
  3709 ** can be set using the sqlite3_bind_*() routines defined here.
  3710 **
  3711 ** ^The first argument to the sqlite3_bind_*() routines is always
  3712 ** a pointer to the [sqlite3_stmt] object returned from
  3713 ** [sqlite3_prepare_v2()] or its variants.
  3714 **
  3715 ** ^The second argument is the index of the SQL parameter to be set.
  3716 ** ^The leftmost SQL parameter has an index of 1.  ^When the same named
  3717 ** SQL parameter is used more than once, second and subsequent
  3718 ** occurrences have the same index as the first occurrence.
  3719 ** ^The index for named parameters can be looked up using the
  3720 ** [sqlite3_bind_parameter_index()] API if desired.  ^The index
  3721 ** for "?NNN" parameters is the value of NNN.
  3722 ** ^The NNN value must be between 1 and the [sqlite3_limit()]
  3723 ** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
  3724 **
  3725 ** ^The third argument is the value to bind to the parameter.
  3726 ** ^If the third parameter to sqlite3_bind_text() or sqlite3_bind_text16()
  3727 ** or sqlite3_bind_blob() is a NULL pointer then the fourth parameter
  3728 ** is ignored and the end result is the same as sqlite3_bind_null().
  3729 **
  3730 ** ^(In those routines that have a fourth argument, its value is the
  3731 ** number of bytes in the parameter.  To be clear: the value is the
  3732 ** number of <u>bytes</u> in the value, not the number of characters.)^
  3733 ** ^If the fourth parameter to sqlite3_bind_text() or sqlite3_bind_text16()
  3734 ** is negative, then the length of the string is
  3735 ** the number of bytes up to the first zero terminator.
  3736 ** If the fourth parameter to sqlite3_bind_blob() is negative, then
  3737 ** the behavior is undefined.
  3738 ** If a non-negative fourth parameter is provided to sqlite3_bind_text()
  3739 ** or sqlite3_bind_text16() or sqlite3_bind_text64() then
  3740 ** that parameter must be the byte offset
  3741 ** where the NUL terminator would occur assuming the string were NUL
  3742 ** terminated.  If any NUL characters occur at byte offsets less than 
  3743 ** the value of the fourth parameter then the resulting string value will
  3744 ** contain embedded NULs.  The result of expressions involving strings
  3745 ** with embedded NULs is undefined.
  3746 **
  3747 ** ^The fifth argument to the BLOB and string binding interfaces
  3748 ** is a destructor used to dispose of the BLOB or
  3749 ** string after SQLite has finished with it.  ^The destructor is called
  3750 ** to dispose of the BLOB or string even if the call to bind API fails.
  3751 ** ^If the fifth argument is
  3752 ** the special value [SQLITE_STATIC], then SQLite assumes that the
  3753 ** information is in static, unmanaged space and does not need to be freed.
  3754 ** ^If the fifth argument has the value [SQLITE_TRANSIENT], then
  3755 ** SQLite makes its own private copy of the data immediately, before
  3756 ** the sqlite3_bind_*() routine returns.
  3757 **
  3758 ** ^The sixth argument to sqlite3_bind_text64() must be one of
  3759 ** [SQLITE_UTF8], [SQLITE_UTF16], [SQLITE_UTF16BE], or [SQLITE_UTF16LE]
  3760 ** to specify the encoding of the text in the third parameter.  If
  3761 ** the sixth argument to sqlite3_bind_text64() is not one of the
  3762 ** allowed values shown above, or if the text encoding is different
  3763 ** from the encoding specified by the sixth parameter, then the behavior
  3764 ** is undefined.
  3765 **
  3766 ** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
  3767 ** is filled with zeroes.  ^A zeroblob uses a fixed amount of memory
  3768 ** (just an integer to hold its size) while it is being processed.
  3769 ** Zeroblobs are intended to serve as placeholders for BLOBs whose
  3770 ** content is later written using
  3771 ** [sqlite3_blob_open | incremental BLOB I/O] routines.
  3772 ** ^A negative value for the zeroblob results in a zero-length BLOB.
  3773 **
  3774 ** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer
  3775 ** for the [prepared statement] or with a prepared statement for which
  3776 ** [sqlite3_step()] has been called more recently than [sqlite3_reset()],
  3777 ** then the call will return [SQLITE_MISUSE].  If any sqlite3_bind_()
  3778 ** routine is passed a [prepared statement] that has been finalized, the
  3779 ** result is undefined and probably harmful.
  3780 **
  3781 ** ^Bindings are not cleared by the [sqlite3_reset()] routine.
  3782 ** ^Unbound parameters are interpreted as NULL.
  3783 **
  3784 ** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an
  3785 ** [error code] if anything goes wrong.
  3786 ** ^[SQLITE_TOOBIG] might be returned if the size of a string or BLOB
  3787 ** exceeds limits imposed by [sqlite3_limit]([SQLITE_LIMIT_LENGTH]) or
  3788 ** [SQLITE_MAX_LENGTH].
  3789 ** ^[SQLITE_RANGE] is returned if the parameter
  3790 ** index is out of range.  ^[SQLITE_NOMEM] is returned if malloc() fails.
  3791 **
  3792 ** See also: [sqlite3_bind_parameter_count()],
  3793 ** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
  3794 */
  3795 SQLITE_API int SQLITE_STDCALL sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
  3796 SQLITE_API int SQLITE_STDCALL sqlite3_bind_blob64(sqlite3_stmt*, int, const void*, sqlite3_uint64,
  3797                         void(*)(void*));
  3798 SQLITE_API int SQLITE_STDCALL sqlite3_bind_double(sqlite3_stmt*, int, double);
  3799 SQLITE_API int SQLITE_STDCALL sqlite3_bind_int(sqlite3_stmt*, int, int);
  3800 SQLITE_API int SQLITE_STDCALL sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);
  3801 SQLITE_API int SQLITE_STDCALL sqlite3_bind_null(sqlite3_stmt*, int);
  3802 SQLITE_API int SQLITE_STDCALL sqlite3_bind_text(sqlite3_stmt*,int,const char*,int,void(*)(void*));
  3803 SQLITE_API int SQLITE_STDCALL sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
  3804 SQLITE_API int SQLITE_STDCALL sqlite3_bind_text64(sqlite3_stmt*, int, const char*, sqlite3_uint64,
  3805                          void(*)(void*), unsigned char encoding);
  3806 SQLITE_API int SQLITE_STDCALL sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*);
  3807 SQLITE_API int SQLITE_STDCALL sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n);
  3808 SQLITE_API int SQLITE_STDCALL sqlite3_bind_zeroblob64(sqlite3_stmt*, int, sqlite3_uint64);
  3809 
  3810 /*
  3811 ** CAPI3REF: Number Of SQL Parameters
  3812 ** METHOD: sqlite3_stmt
  3813 **
  3814 ** ^This routine can be used to find the number of [SQL parameters]
  3815 ** in a [prepared statement].  SQL parameters are tokens of the
  3816 ** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
  3817 ** placeholders for values that are [sqlite3_bind_blob | bound]
  3818 ** to the parameters at a later time.
  3819 **
  3820 ** ^(This routine actually returns the index of the largest (rightmost)
  3821 ** parameter. For all forms except ?NNN, this will correspond to the
  3822 ** number of unique parameters.  If parameters of the ?NNN form are used,
  3823 ** there may be gaps in the list.)^
  3824 **
  3825 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3826 ** [sqlite3_bind_parameter_name()], and
  3827 ** [sqlite3_bind_parameter_index()].
  3828 */
  3829 SQLITE_API int SQLITE_STDCALL sqlite3_bind_parameter_count(sqlite3_stmt*);
  3830 
  3831 /*
  3832 ** CAPI3REF: Name Of A Host Parameter
  3833 ** METHOD: sqlite3_stmt
  3834 **
  3835 ** ^The sqlite3_bind_parameter_name(P,N) interface returns
  3836 ** the name of the N-th [SQL parameter] in the [prepared statement] P.
  3837 ** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
  3838 ** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
  3839 ** respectively.
  3840 ** In other words, the initial ":" or "$" or "@" or "?"
  3841 ** is included as part of the name.)^
  3842 ** ^Parameters of the form "?" without a following integer have no name
  3843 ** and are referred to as "nameless" or "anonymous parameters".
  3844 **
  3845 ** ^The first host parameter has an index of 1, not 0.
  3846 **
  3847 ** ^If the value N is out of range or if the N-th parameter is
  3848 ** nameless, then NULL is returned.  ^The returned string is
  3849 ** always in UTF-8 encoding even if the named parameter was
  3850 ** originally specified as UTF-16 in [sqlite3_prepare16()] or
  3851 ** [sqlite3_prepare16_v2()].
  3852 **
  3853 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3854 ** [sqlite3_bind_parameter_count()], and
  3855 ** [sqlite3_bind_parameter_index()].
  3856 */
  3857 SQLITE_API const char *SQLITE_STDCALL sqlite3_bind_parameter_name(sqlite3_stmt*, int);
  3858 
  3859 /*
  3860 ** CAPI3REF: Index Of A Parameter With A Given Name
  3861 ** METHOD: sqlite3_stmt
  3862 **
  3863 ** ^Return the index of an SQL parameter given its name.  ^The
  3864 ** index value returned is suitable for use as the second
  3865 ** parameter to [sqlite3_bind_blob|sqlite3_bind()].  ^A zero
  3866 ** is returned if no matching parameter is found.  ^The parameter
  3867 ** name must be given in UTF-8 even if the original statement
  3868 ** was prepared from UTF-16 text using [sqlite3_prepare16_v2()].
  3869 **
  3870 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
  3871 ** [sqlite3_bind_parameter_count()], and
  3872 ** [sqlite3_bind_parameter_name()].
  3873 */
  3874 SQLITE_API int SQLITE_STDCALL sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);
  3875 
  3876 /*
  3877 ** CAPI3REF: Reset All Bindings On A Prepared Statement
  3878 ** METHOD: sqlite3_stmt
  3879 **
  3880 ** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset
  3881 ** the [sqlite3_bind_blob | bindings] on a [prepared statement].
  3882 ** ^Use this routine to reset all host parameters to NULL.
  3883 */
  3884 SQLITE_API int SQLITE_STDCALL sqlite3_clear_bindings(sqlite3_stmt*);
  3885 
  3886 /*
  3887 ** CAPI3REF: Number Of Columns In A Result Set
  3888 ** METHOD: sqlite3_stmt
  3889 **
  3890 ** ^Return the number of columns in the result set returned by the
  3891 ** [prepared statement]. ^This routine returns 0 if pStmt is an SQL
  3892 ** statement that does not return data (for example an [UPDATE]).
  3893 **
  3894 ** See also: [sqlite3_data_count()]
  3895 */
  3896 SQLITE_API int SQLITE_STDCALL sqlite3_column_count(sqlite3_stmt *pStmt);
  3897 
  3898 /*
  3899 ** CAPI3REF: Column Names In A Result Set
  3900 ** METHOD: sqlite3_stmt
  3901 **
  3902 ** ^These routines return the name assigned to a particular column
  3903 ** in the result set of a [SELECT] statement.  ^The sqlite3_column_name()
  3904 ** interface returns a pointer to a zero-terminated UTF-8 string
  3905 ** and sqlite3_column_name16() returns a pointer to a zero-terminated
  3906 ** UTF-16 string.  ^The first parameter is the [prepared statement]
  3907 ** that implements the [SELECT] statement. ^The second parameter is the
  3908 ** column number.  ^The leftmost column is number 0.
  3909 **
  3910 ** ^The returned string pointer is valid until either the [prepared statement]
  3911 ** is destroyed by [sqlite3_finalize()] or until the statement is automatically
  3912 ** reprepared by the first call to [sqlite3_step()] for a particular run
  3913 ** or until the next call to
  3914 ** sqlite3_column_name() or sqlite3_column_name16() on the same column.
  3915 **
  3916 ** ^If sqlite3_malloc() fails during the processing of either routine
  3917 ** (for example during a conversion from UTF-8 to UTF-16) then a
  3918 ** NULL pointer is returned.
  3919 **
  3920 ** ^The name of a result column is the value of the "AS" clause for
  3921 ** that column, if there is an AS clause.  If there is no AS clause
  3922 ** then the name of the column is unspecified and may change from
  3923 ** one release of SQLite to the next.
  3924 */
  3925 SQLITE_API const char *SQLITE_STDCALL sqlite3_column_name(sqlite3_stmt*, int N);
  3926 SQLITE_API const void *SQLITE_STDCALL sqlite3_column_name16(sqlite3_stmt*, int N);
  3927 
  3928 /*
  3929 ** CAPI3REF: Source Of Data In A Query Result
  3930 ** METHOD: sqlite3_stmt
  3931 **
  3932 ** ^These routines provide a means to determine the database, table, and
  3933 ** table column that is the origin of a particular result column in
  3934 ** [SELECT] statement.
  3935 ** ^The name of the database or table or column can be returned as
  3936 ** either a UTF-8 or UTF-16 string.  ^The _database_ routines return
  3937 ** the database name, the _table_ routines return the table name, and
  3938 ** the origin_ routines return the column name.
  3939 ** ^The returned string is valid until the [prepared statement] is destroyed
  3940 ** using [sqlite3_finalize()] or until the statement is automatically
  3941 ** reprepared by the first call to [sqlite3_step()] for a particular run
  3942 ** or until the same information is requested
  3943 ** again in a different encoding.
  3944 **
  3945 ** ^The names returned are the original un-aliased names of the
  3946 ** database, table, and column.
  3947 **
  3948 ** ^The first argument to these interfaces is a [prepared statement].
  3949 ** ^These functions return information about the Nth result column returned by
  3950 ** the statement, where N is the second function argument.
  3951 ** ^The left-most column is column 0 for these routines.
  3952 **
  3953 ** ^If the Nth column returned by the statement is an expression or
  3954 ** subquery and is not a column value, then all of these functions return
  3955 ** NULL.  ^These routine might also return NULL if a memory allocation error
  3956 ** occurs.  ^Otherwise, they return the name of the attached database, table,
  3957 ** or column that query result column was extracted from.
  3958 **
  3959 ** ^As with all other SQLite APIs, those whose names end with "16" return
  3960 ** UTF-16 encoded strings and the other functions return UTF-8.
  3961 **
  3962 ** ^These APIs are only available if the library was compiled with the
  3963 ** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol.
  3964 **
  3965 ** If two or more threads call one or more of these routines against the same
  3966 ** prepared statement and column at the same time then the results are
  3967 ** undefined.
  3968 **
  3969 ** If two or more threads call one or more
  3970 ** [sqlite3_column_database_name | column metadata interfaces]
  3971 ** for the same [prepared statement] and result column
  3972 ** at the same time then the results are undefined.
  3973 */
  3974 SQLITE_API const char *SQLITE_STDCALL sqlite3_column_database_name(sqlite3_stmt*,int);
  3975 SQLITE_API const void *SQLITE_STDCALL sqlite3_column_database_name16(sqlite3_stmt*,int);
  3976 SQLITE_API const char *SQLITE_STDCALL sqlite3_column_table_name(sqlite3_stmt*,int);
  3977 SQLITE_API const void *SQLITE_STDCALL sqlite3_column_table_name16(sqlite3_stmt*,int);
  3978 SQLITE_API const char *SQLITE_STDCALL sqlite3_column_origin_name(sqlite3_stmt*,int);
  3979 SQLITE_API const void *SQLITE_STDCALL sqlite3_column_origin_name16(sqlite3_stmt*,int);
  3980 
  3981 /*
  3982 ** CAPI3REF: Declared Datatype Of A Query Result
  3983 ** METHOD: sqlite3_stmt
  3984 **
  3985 ** ^(The first parameter is a [prepared statement].
  3986 ** If this statement is a [SELECT] statement and the Nth column of the
  3987 ** returned result set of that [SELECT] is a table column (not an
  3988 ** expression or subquery) then the declared type of the table
  3989 ** column is returned.)^  ^If the Nth column of the result set is an
  3990 ** expression or subquery, then a NULL pointer is returned.
  3991 ** ^The returned string is always UTF-8 encoded.
  3992 **
  3993 ** ^(For example, given the database schema:
  3994 **
  3995 ** CREATE TABLE t1(c1 VARIANT);
  3996 **
  3997 ** and the following statement to be compiled:
  3998 **
  3999 ** SELECT c1 + 1, c1 FROM t1;
  4000 **
  4001 ** this routine would return the string "VARIANT" for the second result
  4002 ** column (i==1), and a NULL pointer for the first result column (i==0).)^
  4003 **
  4004 ** ^SQLite uses dynamic run-time typing.  ^So just because a column
  4005 ** is declared to contain a particular type does not mean that the
  4006 ** data stored in that column is of the declared type.  SQLite is
  4007 ** strongly typed, but the typing is dynamic not static.  ^Type
  4008 ** is associated with individual values, not with the containers
  4009 ** used to hold those values.
  4010 */
  4011 SQLITE_API const char *SQLITE_STDCALL sqlite3_column_decltype(sqlite3_stmt*,int);
  4012 SQLITE_API const void *SQLITE_STDCALL sqlite3_column_decltype16(sqlite3_stmt*,int);
  4013 
  4014 /*
  4015 ** CAPI3REF: Evaluate An SQL Statement
  4016 ** METHOD: sqlite3_stmt
  4017 **
  4018 ** After a [prepared statement] has been prepared using either
  4019 ** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy
  4020 ** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
  4021 ** must be called one or more times to evaluate the statement.
  4022 **
  4023 ** The details of the behavior of the sqlite3_step() interface depend
  4024 ** on whether the statement was prepared using the newer "v2" interface
  4025 ** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy
  4026 ** interface [sqlite3_prepare()] and [sqlite3_prepare16()].  The use of the
  4027 ** new "v2" interface is recommended for new applications but the legacy
  4028 ** interface will continue to be supported.
  4029 **
  4030 ** ^In the legacy interface, the return value will be either [SQLITE_BUSY],
  4031 ** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
  4032 ** ^With the "v2" interface, any of the other [result codes] or
  4033 ** [extended result codes] might be returned as well.
  4034 **
  4035 ** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
  4036 ** database locks it needs to do its job.  ^If the statement is a [COMMIT]
  4037 ** or occurs outside of an explicit transaction, then you can retry the
  4038 ** statement.  If the statement is not a [COMMIT] and occurs within an
  4039 ** explicit transaction then you should rollback the transaction before
  4040 ** continuing.
  4041 **
  4042 ** ^[SQLITE_DONE] means that the statement has finished executing
  4043 ** successfully.  sqlite3_step() should not be called again on this virtual
  4044 ** machine without first calling [sqlite3_reset()] to reset the virtual
  4045 ** machine back to its initial state.
  4046 **
  4047 ** ^If the SQL statement being executed returns any data, then [SQLITE_ROW]
  4048 ** is returned each time a new row of data is ready for processing by the
  4049 ** caller. The values may be accessed using the [column access functions].
  4050 ** sqlite3_step() is called again to retrieve the next row of data.
  4051 **
  4052 ** ^[SQLITE_ERROR] means that a run-time error (such as a constraint
  4053 ** violation) has occurred.  sqlite3_step() should not be called again on
  4054 ** the VM. More information may be found by calling [sqlite3_errmsg()].
  4055 ** ^With the legacy interface, a more specific error code (for example,
  4056 ** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
  4057 ** can be obtained by calling [sqlite3_reset()] on the
  4058 ** [prepared statement].  ^In the "v2" interface,
  4059 ** the more specific error code is returned directly by sqlite3_step().
  4060 **
  4061 ** [SQLITE_MISUSE] means that the this routine was called inappropriately.
  4062 ** Perhaps it was called on a [prepared statement] that has
  4063 ** already been [sqlite3_finalize | finalized] or on one that had
  4064 ** previously returned [SQLITE_ERROR] or [SQLITE_DONE].  Or it could
  4065 ** be the case that the same database connection is being used by two or
  4066 ** more threads at the same moment in time.
  4067 **
  4068 ** For all versions of SQLite up to and including 3.6.23.1, a call to
  4069 ** [sqlite3_reset()] was required after sqlite3_step() returned anything
  4070 ** other than [SQLITE_ROW] before any subsequent invocation of
  4071 ** sqlite3_step().  Failure to reset the prepared statement using 
  4072 ** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
  4073 ** sqlite3_step().  But after version 3.6.23.1, sqlite3_step() began
  4074 ** calling [sqlite3_reset()] automatically in this circumstance rather
  4075 ** than returning [SQLITE_MISUSE].  This is not considered a compatibility
  4076 ** break because any application that ever receives an SQLITE_MISUSE error
  4077 ** is broken by definition.  The [SQLITE_OMIT_AUTORESET] compile-time option
  4078 ** can be used to restore the legacy behavior.
  4079 **
  4080 ** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
  4081 ** API always returns a generic error code, [SQLITE_ERROR], following any
  4082 ** error other than [SQLITE_BUSY] and [SQLITE_MISUSE].  You must call
  4083 ** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
  4084 ** specific [error codes] that better describes the error.
  4085 ** We admit that this is a goofy design.  The problem has been fixed
  4086 ** with the "v2" interface.  If you prepare all of your SQL statements
  4087 ** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead
  4088 ** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
  4089 ** then the more specific [error codes] are returned directly
  4090 ** by sqlite3_step().  The use of the "v2" interface is recommended.
  4091 */
  4092 SQLITE_API int SQLITE_STDCALL sqlite3_step(sqlite3_stmt*);
  4093 
  4094 /*
  4095 ** CAPI3REF: Number of columns in a result set
  4096 ** METHOD: sqlite3_stmt
  4097 **
  4098 ** ^The sqlite3_data_count(P) interface returns the number of columns in the
  4099 ** current row of the result set of [prepared statement] P.
  4100 ** ^If prepared statement P does not have results ready to return
  4101 ** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
  4102 ** interfaces) then sqlite3_data_count(P) returns 0.
  4103 ** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
  4104 ** ^The sqlite3_data_count(P) routine returns 0 if the previous call to
  4105 ** [sqlite3_step](P) returned [SQLITE_DONE].  ^The sqlite3_data_count(P)
  4106 ** will return non-zero if previous call to [sqlite3_step](P) returned
  4107 ** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]
  4108 ** where it always returns zero since each step of that multi-step
  4109 ** pragma returns 0 columns of data.
  4110 **
  4111 ** See also: [sqlite3_column_count()]
  4112 */
  4113 SQLITE_API int SQLITE_STDCALL sqlite3_data_count(sqlite3_stmt *pStmt);
  4114 
  4115 /*
  4116 ** CAPI3REF: Fundamental Datatypes
  4117 ** KEYWORDS: SQLITE_TEXT
  4118 **
  4119 ** ^(Every value in SQLite has one of five fundamental datatypes:
  4120 **
  4121 ** <ul>
  4122 ** <li> 64-bit signed integer
  4123 ** <li> 64-bit IEEE floating point number
  4124 ** <li> string
  4125 ** <li> BLOB
  4126 ** <li> NULL
  4127 ** </ul>)^
  4128 **
  4129 ** These constants are codes for each of those types.
  4130 **
  4131 ** Note that the SQLITE_TEXT constant was also used in SQLite version 2
  4132 ** for a completely different meaning.  Software that links against both
  4133 ** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
  4134 ** SQLITE_TEXT.
  4135 */
  4136 #define SQLITE_INTEGER  1
  4137 #define SQLITE_FLOAT    2
  4138 #define SQLITE_BLOB     4
  4139 #define SQLITE_NULL     5
  4140 #ifdef SQLITE_TEXT
  4141 # undef SQLITE_TEXT
  4142 #else
  4143 # define SQLITE_TEXT     3
  4144 #endif
  4145 #define SQLITE3_TEXT     3
  4146 
  4147 /*
  4148 ** CAPI3REF: Result Values From A Query
  4149 ** KEYWORDS: {column access functions}
  4150 ** METHOD: sqlite3_stmt
  4151 **
  4152 ** ^These routines return information about a single column of the current
  4153 ** result row of a query.  ^In every case the first argument is a pointer
  4154 ** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
  4155 ** that was returned from [sqlite3_prepare_v2()] or one of its variants)
  4156 ** and the second argument is the index of the column for which information
  4157 ** should be returned. ^The leftmost column of the result set has the index 0.
  4158 ** ^The number of columns in the result can be determined using
  4159 ** [sqlite3_column_count()].
  4160 **
  4161 ** If the SQL statement does not currently point to a valid row, or if the
  4162 ** column index is out of range, the result is undefined.
  4163 ** These routines may only be called when the most recent call to
  4164 ** [sqlite3_step()] has returned [SQLITE_ROW] and neither
  4165 ** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
  4166 ** If any of these routines are called after [sqlite3_reset()] or
  4167 ** [sqlite3_finalize()] or after [sqlite3_step()] has returned
  4168 ** something other than [SQLITE_ROW], the results are undefined.
  4169 ** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
  4170 ** are called from a different thread while any of these routines
  4171 ** are pending, then the results are undefined.
  4172 **
  4173 ** ^The sqlite3_column_type() routine returns the
  4174 ** [SQLITE_INTEGER | datatype code] for the initial data type
  4175 ** of the result column.  ^The returned value is one of [SQLITE_INTEGER],
  4176 ** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL].  The value
  4177 ** returned by sqlite3_column_type() is only meaningful if no type
  4178 ** conversions have occurred as described below.  After a type conversion,
  4179 ** the value returned by sqlite3_column_type() is undefined.  Future
  4180 ** versions of SQLite may change the behavior of sqlite3_column_type()
  4181 ** following a type conversion.
  4182 **
  4183 ** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
  4184 ** routine returns the number of bytes in that BLOB or string.
  4185 ** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts
  4186 ** the string to UTF-8 and then returns the number of bytes.
  4187 ** ^If the result is a numeric value then sqlite3_column_bytes() uses
  4188 ** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
  4189 ** the number of bytes in that string.
  4190 ** ^If the result is NULL, then sqlite3_column_bytes() returns zero.
  4191 **
  4192 ** ^If the result is a BLOB or UTF-16 string then the sqlite3_column_bytes16()
  4193 ** routine returns the number of bytes in that BLOB or string.
  4194 ** ^If the result is a UTF-8 string, then sqlite3_column_bytes16() converts
  4195 ** the string to UTF-16 and then returns the number of bytes.
  4196 ** ^If the result is a numeric value then sqlite3_column_bytes16() uses
  4197 ** [sqlite3_snprintf()] to convert that value to a UTF-16 string and returns
  4198 ** the number of bytes in that string.
  4199 ** ^If the result is NULL, then sqlite3_column_bytes16() returns zero.
  4200 **
  4201 ** ^The values returned by [sqlite3_column_bytes()] and 
  4202 ** [sqlite3_column_bytes16()] do not include the zero terminators at the end
  4203 ** of the string.  ^For clarity: the values returned by
  4204 ** [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] are the number of
  4205 ** bytes in the string, not the number of characters.
  4206 **
  4207 ** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
  4208 ** even empty strings, are always zero-terminated.  ^The return
  4209 ** value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer.
  4210 **
  4211 ** <b>Warning:</b> ^The object returned by [sqlite3_column_value()] is an
  4212 ** [unprotected sqlite3_value] object.  In a multithreaded environment,
  4213 ** an unprotected sqlite3_value object may only be used safely with
  4214 ** [sqlite3_bind_value()] and [sqlite3_result_value()].
  4215 ** If the [unprotected sqlite3_value] object returned by
  4216 ** [sqlite3_column_value()] is used in any other way, including calls
  4217 ** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
  4218 ** or [sqlite3_value_bytes()], the behavior is not threadsafe.
  4219 **
  4220 ** These routines attempt to convert the value where appropriate.  ^For
  4221 ** example, if the internal representation is FLOAT and a text result
  4222 ** is requested, [sqlite3_snprintf()] is used internally to perform the
  4223 ** conversion automatically.  ^(The following table details the conversions
  4224 ** that are applied:
  4225 **
  4226 ** <blockquote>
  4227 ** <table border="1">
  4228 ** <tr><th> Internal<br>Type <th> Requested<br>Type <th>  Conversion
  4229 **
  4230 ** <tr><td>  NULL    <td> INTEGER   <td> Result is 0
  4231 ** <tr><td>  NULL    <td>  FLOAT    <td> Result is 0.0
  4232 ** <tr><td>  NULL    <td>   TEXT    <td> Result is a NULL pointer
  4233 ** <tr><td>  NULL    <td>   BLOB    <td> Result is a NULL pointer
  4234 ** <tr><td> INTEGER  <td>  FLOAT    <td> Convert from integer to float
  4235 ** <tr><td> INTEGER  <td>   TEXT    <td> ASCII rendering of the integer
  4236 ** <tr><td> INTEGER  <td>   BLOB    <td> Same as INTEGER->TEXT
  4237 ** <tr><td>  FLOAT   <td> INTEGER   <td> [CAST] to INTEGER
  4238 ** <tr><td>  FLOAT   <td>   TEXT    <td> ASCII rendering of the float
  4239 ** <tr><td>  FLOAT   <td>   BLOB    <td> [CAST] to BLOB
  4240 ** <tr><td>  TEXT    <td> INTEGER   <td> [CAST] to INTEGER
  4241 ** <tr><td>  TEXT    <td>  FLOAT    <td> [CAST] to REAL
  4242 ** <tr><td>  TEXT    <td>   BLOB    <td> No change
  4243 ** <tr><td>  BLOB    <td> INTEGER   <td> [CAST] to INTEGER
  4244 ** <tr><td>  BLOB    <td>  FLOAT    <td> [CAST] to REAL
  4245 ** <tr><td>  BLOB    <td>   TEXT    <td> Add a zero terminator if needed
  4246 ** </table>
  4247 ** </blockquote>)^
  4248 **
  4249 ** Note that when type conversions occur, pointers returned by prior
  4250 ** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
  4251 ** sqlite3_column_text16() may be invalidated.
  4252 ** Type conversions and pointer invalidations might occur
  4253 ** in the following cases:
  4254 **
  4255 ** <ul>
  4256 ** <li> The initial content is a BLOB and sqlite3_column_text() or
  4257 **      sqlite3_column_text16() is called.  A zero-terminator might
  4258 **      need to be added to the string.</li>
  4259 ** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
  4260 **      sqlite3_column_text16() is called.  The content must be converted
  4261 **      to UTF-16.</li>
  4262 ** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
  4263 **      sqlite3_column_text() is called.  The content must be converted
  4264 **      to UTF-8.</li>
  4265 ** </ul>
  4266 **
  4267 ** ^Conversions between UTF-16be and UTF-16le are always done in place and do
  4268 ** not invalidate a prior pointer, though of course the content of the buffer
  4269 ** that the prior pointer references will have been modified.  Other kinds
  4270 ** of conversion are done in place when it is possible, but sometimes they
  4271 ** are not possible and in those cases prior pointers are invalidated.
  4272 **
  4273 ** The safest policy is to invoke these routines
  4274 ** in one of the following ways:
  4275 **
  4276 ** <ul>
  4277 **  <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
  4278 **  <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
  4279 **  <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
  4280 ** </ul>
  4281 **
  4282 ** In other words, you should call sqlite3_column_text(),
  4283 ** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
  4284 ** into the desired format, then invoke sqlite3_column_bytes() or
  4285 ** sqlite3_column_bytes16() to find the size of the result.  Do not mix calls
  4286 ** to sqlite3_column_text() or sqlite3_column_blob() with calls to
  4287 ** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
  4288 ** with calls to sqlite3_column_bytes().
  4289 **
  4290 ** ^The pointers returned are valid until a type conversion occurs as
  4291 ** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
  4292 ** [sqlite3_finalize()] is called.  ^The memory space used to hold strings
  4293 ** and BLOBs is freed automatically.  Do <em>not</em> pass the pointers returned
  4294 ** from [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
  4295 ** [sqlite3_free()].
  4296 **
  4297 ** ^(If a memory allocation error occurs during the evaluation of any
  4298 ** of these routines, a default value is returned.  The default value
  4299 ** is either the integer 0, the floating point number 0.0, or a NULL
  4300 ** pointer.  Subsequent calls to [sqlite3_errcode()] will return
  4301 ** [SQLITE_NOMEM].)^
  4302 */
  4303 SQLITE_API const void *SQLITE_STDCALL sqlite3_column_blob(sqlite3_stmt*, int iCol);
  4304 SQLITE_API int SQLITE_STDCALL sqlite3_column_bytes(sqlite3_stmt*, int iCol);
  4305 SQLITE_API int SQLITE_STDCALL sqlite3_column_bytes16(sqlite3_stmt*, int iCol);
  4306 SQLITE_API double SQLITE_STDCALL sqlite3_column_double(sqlite3_stmt*, int iCol);
  4307 SQLITE_API int SQLITE_STDCALL sqlite3_column_int(sqlite3_stmt*, int iCol);
  4308 SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3_column_int64(sqlite3_stmt*, int iCol);
  4309 SQLITE_API const unsigned char *SQLITE_STDCALL sqlite3_column_text(sqlite3_stmt*, int iCol);
  4310 SQLITE_API const void *SQLITE_STDCALL sqlite3_column_text16(sqlite3_stmt*, int iCol);
  4311 SQLITE_API int SQLITE_STDCALL sqlite3_column_type(sqlite3_stmt*, int iCol);
  4312 SQLITE_API sqlite3_value *SQLITE_STDCALL sqlite3_column_value(sqlite3_stmt*, int iCol);
  4313 
  4314 /*
  4315 ** CAPI3REF: Destroy A Prepared Statement Object
  4316 ** DESTRUCTOR: sqlite3_stmt
  4317 **
  4318 ** ^The sqlite3_finalize() function is called to delete a [prepared statement].
  4319 ** ^If the most recent evaluation of the statement encountered no errors
  4320 ** or if the statement is never been evaluated, then sqlite3_finalize() returns
  4321 ** SQLITE_OK.  ^If the most recent evaluation of statement S failed, then
  4322 ** sqlite3_finalize(S) returns the appropriate [error code] or
  4323 ** [extended error code].
  4324 **
  4325 ** ^The sqlite3_finalize(S) routine can be called at any point during
  4326 ** the life cycle of [prepared statement] S:
  4327 ** before statement S is ever evaluated, after
  4328 ** one or more calls to [sqlite3_reset()], or after any call
  4329 ** to [sqlite3_step()] regardless of whether or not the statement has
  4330 ** completed execution.
  4331 **
  4332 ** ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op.
  4333 **
  4334 ** The application must finalize every [prepared statement] in order to avoid
  4335 ** resource leaks.  It is a grievous error for the application to try to use
  4336 ** a prepared statement after it has been finalized.  Any use of a prepared
  4337 ** statement after it has been finalized can result in undefined and
  4338 ** undesirable behavior such as segfaults and heap corruption.
  4339 */
  4340 SQLITE_API int SQLITE_STDCALL sqlite3_finalize(sqlite3_stmt *pStmt);
  4341 
  4342 /*
  4343 ** CAPI3REF: Reset A Prepared Statement Object
  4344 ** METHOD: sqlite3_stmt
  4345 **
  4346 ** The sqlite3_reset() function is called to reset a [prepared statement]
  4347 ** object back to its initial state, ready to be re-executed.
  4348 ** ^Any SQL statement variables that had values bound to them using
  4349 ** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
  4350 ** Use [sqlite3_clear_bindings()] to reset the bindings.
  4351 **
  4352 ** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S
  4353 ** back to the beginning of its program.
  4354 **
  4355 ** ^If the most recent call to [sqlite3_step(S)] for the
  4356 ** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
  4357 ** or if [sqlite3_step(S)] has never before been called on S,
  4358 ** then [sqlite3_reset(S)] returns [SQLITE_OK].
  4359 **
  4360 ** ^If the most recent call to [sqlite3_step(S)] for the
  4361 ** [prepared statement] S indicated an error, then
  4362 ** [sqlite3_reset(S)] returns an appropriate [error code].
  4363 **
  4364 ** ^The [sqlite3_reset(S)] interface does not change the values
  4365 ** of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
  4366 */
  4367 SQLITE_API int SQLITE_STDCALL sqlite3_reset(sqlite3_stmt *pStmt);
  4368 
  4369 /*
  4370 ** CAPI3REF: Create Or Redefine SQL Functions
  4371 ** KEYWORDS: {function creation routines}
  4372 ** KEYWORDS: {application-defined SQL function}
  4373 ** KEYWORDS: {application-defined SQL functions}
  4374 ** METHOD: sqlite3
  4375 **
  4376 ** ^These functions (collectively known as "function creation routines")
  4377 ** are used to add SQL functions or aggregates or to redefine the behavior
  4378 ** of existing SQL functions or aggregates.  The only differences between
  4379 ** these routines are the text encoding expected for
  4380 ** the second parameter (the name of the function being created)
  4381 ** and the presence or absence of a destructor callback for
  4382 ** the application data pointer.
  4383 **
  4384 ** ^The first parameter is the [database connection] to which the SQL
  4385 ** function is to be added.  ^If an application uses more than one database
  4386 ** connection then application-defined SQL functions must be added
  4387 ** to each database connection separately.
  4388 **
  4389 ** ^The second parameter is the name of the SQL function to be created or
  4390 ** redefined.  ^The length of the name is limited to 255 bytes in a UTF-8
  4391 ** representation, exclusive of the zero-terminator.  ^Note that the name
  4392 ** length limit is in UTF-8 bytes, not characters nor UTF-16 bytes.  
  4393 ** ^Any attempt to create a function with a longer name
  4394 ** will result in [SQLITE_MISUSE] being returned.
  4395 **
  4396 ** ^The third parameter (nArg)
  4397 ** is the number of arguments that the SQL function or
  4398 ** aggregate takes. ^If this parameter is -1, then the SQL function or
  4399 ** aggregate may take any number of arguments between 0 and the limit
  4400 ** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]).  If the third
  4401 ** parameter is less than -1 or greater than 127 then the behavior is
  4402 ** undefined.
  4403 **
  4404 ** ^The fourth parameter, eTextRep, specifies what
  4405 ** [SQLITE_UTF8 | text encoding] this SQL function prefers for
  4406 ** its parameters.  The application should set this parameter to
  4407 ** [SQLITE_UTF16LE] if the function implementation invokes 
  4408 ** [sqlite3_value_text16le()] on an input, or [SQLITE_UTF16BE] if the
  4409 ** implementation invokes [sqlite3_value_text16be()] on an input, or
  4410 ** [SQLITE_UTF16] if [sqlite3_value_text16()] is used, or [SQLITE_UTF8]
  4411 ** otherwise.  ^The same SQL function may be registered multiple times using
  4412 ** different preferred text encodings, with different implementations for
  4413 ** each encoding.
  4414 ** ^When multiple implementations of the same function are available, SQLite
  4415 ** will pick the one that involves the least amount of data conversion.
  4416 **
  4417 ** ^The fourth parameter may optionally be ORed with [SQLITE_DETERMINISTIC]
  4418 ** to signal that the function will always return the same result given
  4419 ** the same inputs within a single SQL statement.  Most SQL functions are
  4420 ** deterministic.  The built-in [random()] SQL function is an example of a
  4421 ** function that is not deterministic.  The SQLite query planner is able to
  4422 ** perform additional optimizations on deterministic functions, so use
  4423 ** of the [SQLITE_DETERMINISTIC] flag is recommended where possible.
  4424 **
  4425 ** ^(The fifth parameter is an arbitrary pointer.  The implementation of the
  4426 ** function can gain access to this pointer using [sqlite3_user_data()].)^
  4427 **
  4428 ** ^The sixth, seventh and eighth parameters, xFunc, xStep and xFinal, are
  4429 ** pointers to C-language functions that implement the SQL function or
  4430 ** aggregate. ^A scalar SQL function requires an implementation of the xFunc
  4431 ** callback only; NULL pointers must be passed as the xStep and xFinal
  4432 ** parameters. ^An aggregate SQL function requires an implementation of xStep
  4433 ** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
  4434 ** SQL function or aggregate, pass NULL pointers for all three function
  4435 ** callbacks.
  4436 **
  4437 ** ^(If the ninth parameter to sqlite3_create_function_v2() is not NULL,
  4438 ** then it is destructor for the application data pointer. 
  4439 ** The destructor is invoked when the function is deleted, either by being
  4440 ** overloaded or when the database connection closes.)^
  4441 ** ^The destructor is also invoked if the call to
  4442 ** sqlite3_create_function_v2() fails.
  4443 ** ^When the destructor callback of the tenth parameter is invoked, it
  4444 ** is passed a single argument which is a copy of the application data 
  4445 ** pointer which was the fifth parameter to sqlite3_create_function_v2().
  4446 **
  4447 ** ^It is permitted to register multiple implementations of the same
  4448 ** functions with the same name but with either differing numbers of
  4449 ** arguments or differing preferred text encodings.  ^SQLite will use
  4450 ** the implementation that most closely matches the way in which the
  4451 ** SQL function is used.  ^A function implementation with a non-negative
  4452 ** nArg parameter is a better match than a function implementation with
  4453 ** a negative nArg.  ^A function where the preferred text encoding
  4454 ** matches the database encoding is a better
  4455 ** match than a function where the encoding is different.  
  4456 ** ^A function where the encoding difference is between UTF16le and UTF16be
  4457 ** is a closer match than a function where the encoding difference is
  4458 ** between UTF8 and UTF16.
  4459 **
  4460 ** ^Built-in functions may be overloaded by new application-defined functions.
  4461 **
  4462 ** ^An application-defined function is permitted to call other
  4463 ** SQLite interfaces.  However, such calls must not
  4464 ** close the database connection nor finalize or reset the prepared
  4465 ** statement in which the function is running.
  4466 */
  4467 SQLITE_API int SQLITE_STDCALL sqlite3_create_function(
  4468   sqlite3 *db,
  4469   const char *zFunctionName,
  4470   int nArg,
  4471   int eTextRep,
  4472   void *pApp,
  4473   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4474   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4475   void (*xFinal)(sqlite3_context*)
  4476 );
  4477 SQLITE_API int SQLITE_STDCALL sqlite3_create_function16(
  4478   sqlite3 *db,
  4479   const void *zFunctionName,
  4480   int nArg,
  4481   int eTextRep,
  4482   void *pApp,
  4483   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4484   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4485   void (*xFinal)(sqlite3_context*)
  4486 );
  4487 SQLITE_API int SQLITE_STDCALL sqlite3_create_function_v2(
  4488   sqlite3 *db,
  4489   const char *zFunctionName,
  4490   int nArg,
  4491   int eTextRep,
  4492   void *pApp,
  4493   void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
  4494   void (*xStep)(sqlite3_context*,int,sqlite3_value**),
  4495   void (*xFinal)(sqlite3_context*),
  4496   void(*xDestroy)(void*)
  4497 );
  4498 
  4499 /*
  4500 ** CAPI3REF: Text Encodings
  4501 **
  4502 ** These constant define integer codes that represent the various
  4503 ** text encodings supported by SQLite.
  4504 */
  4505 #define SQLITE_UTF8           1    /* IMP: R-37514-35566 */
  4506 #define SQLITE_UTF16LE        2    /* IMP: R-03371-37637 */
  4507 #define SQLITE_UTF16BE        3    /* IMP: R-51971-34154 */
  4508 #define SQLITE_UTF16          4    /* Use native byte order */
  4509 #define SQLITE_ANY            5    /* Deprecated */
  4510 #define SQLITE_UTF16_ALIGNED  8    /* sqlite3_create_collation only */
  4511 
  4512 /*
  4513 ** CAPI3REF: Function Flags
  4514 **
  4515 ** These constants may be ORed together with the 
  4516 ** [SQLITE_UTF8 | preferred text encoding] as the fourth argument
  4517 ** to [sqlite3_create_function()], [sqlite3_create_function16()], or
  4518 ** [sqlite3_create_function_v2()].
  4519 */
  4520 #define SQLITE_DETERMINISTIC    0x800
  4521 
  4522 /*
  4523 ** CAPI3REF: Deprecated Functions
  4524 ** DEPRECATED
  4525 **
  4526 ** These functions are [deprecated].  In order to maintain
  4527 ** backwards compatibility with older code, these functions continue 
  4528 ** to be supported.  However, new applications should avoid
  4529 ** the use of these functions.  To encourage programmers to avoid
  4530 ** these functions, we will not explain what they do.
  4531 */
  4532 #ifndef SQLITE_OMIT_DEPRECATED
  4533 SQLITE_API SQLITE_DEPRECATED int SQLITE_STDCALL sqlite3_aggregate_count(sqlite3_context*);
  4534 SQLITE_API SQLITE_DEPRECATED int SQLITE_STDCALL sqlite3_expired(sqlite3_stmt*);
  4535 SQLITE_API SQLITE_DEPRECATED int SQLITE_STDCALL sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*);
  4536 SQLITE_API SQLITE_DEPRECATED int SQLITE_STDCALL sqlite3_global_recover(void);
  4537 SQLITE_API SQLITE_DEPRECATED void SQLITE_STDCALL sqlite3_thread_cleanup(void);
  4538 SQLITE_API SQLITE_DEPRECATED int SQLITE_STDCALL sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),
  4539                       void*,sqlite3_int64);
  4540 #endif
  4541 
  4542 /*
  4543 ** CAPI3REF: Obtaining SQL Values
  4544 ** METHOD: sqlite3_value
  4545 **
  4546 ** The C-language implementation of SQL functions and aggregates uses
  4547 ** this set of interface routines to access the parameter values on
  4548 ** the function or aggregate.  
  4549 **
  4550 ** The xFunc (for scalar functions) or xStep (for aggregates) parameters
  4551 ** to [sqlite3_create_function()] and [sqlite3_create_function16()]
  4552 ** define callbacks that implement the SQL functions and aggregates.
  4553 ** The 3rd parameter to these callbacks is an array of pointers to
  4554 ** [protected sqlite3_value] objects.  There is one [sqlite3_value] object for
  4555 ** each parameter to the SQL function.  These routines are used to
  4556 ** extract values from the [sqlite3_value] objects.
  4557 **
  4558 ** These routines work only with [protected sqlite3_value] objects.
  4559 ** Any attempt to use these routines on an [unprotected sqlite3_value]
  4560 ** object results in undefined behavior.
  4561 **
  4562 ** ^These routines work just like the corresponding [column access functions]
  4563 ** except that these routines take a single [protected sqlite3_value] object
  4564 ** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
  4565 **
  4566 ** ^The sqlite3_value_text16() interface extracts a UTF-16 string
  4567 ** in the native byte-order of the host machine.  ^The
  4568 ** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
  4569 ** extract UTF-16 strings as big-endian and little-endian respectively.
  4570 **
  4571 ** ^(The sqlite3_value_numeric_type() interface attempts to apply
  4572 ** numeric affinity to the value.  This means that an attempt is
  4573 ** made to convert the value to an integer or floating point.  If
  4574 ** such a conversion is possible without loss of information (in other
  4575 ** words, if the value is a string that looks like a number)
  4576 ** then the conversion is performed.  Otherwise no conversion occurs.
  4577 ** The [SQLITE_INTEGER | datatype] after conversion is returned.)^
  4578 **
  4579 ** Please pay particular attention to the fact that the pointer returned
  4580 ** from [sqlite3_value_blob()], [sqlite3_value_text()], or
  4581 ** [sqlite3_value_text16()] can be invalidated by a subsequent call to
  4582 ** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
  4583 ** or [sqlite3_value_text16()].
  4584 **
  4585 ** These routines must be called from the same thread as
  4586 ** the SQL function that supplied the [sqlite3_value*] parameters.
  4587 */
  4588 SQLITE_API const void *SQLITE_STDCALL sqlite3_value_blob(sqlite3_value*);
  4589 SQLITE_API int SQLITE_STDCALL sqlite3_value_bytes(sqlite3_value*);
  4590 SQLITE_API int SQLITE_STDCALL sqlite3_value_bytes16(sqlite3_value*);
  4591 SQLITE_API double SQLITE_STDCALL sqlite3_value_double(sqlite3_value*);
  4592 SQLITE_API int SQLITE_STDCALL sqlite3_value_int(sqlite3_value*);
  4593 SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3_value_int64(sqlite3_value*);
  4594 SQLITE_API const unsigned char *SQLITE_STDCALL sqlite3_value_text(sqlite3_value*);
  4595 SQLITE_API const void *SQLITE_STDCALL sqlite3_value_text16(sqlite3_value*);
  4596 SQLITE_API const void *SQLITE_STDCALL sqlite3_value_text16le(sqlite3_value*);
  4597 SQLITE_API const void *SQLITE_STDCALL sqlite3_value_text16be(sqlite3_value*);
  4598 SQLITE_API int SQLITE_STDCALL sqlite3_value_type(sqlite3_value*);
  4599 SQLITE_API int SQLITE_STDCALL sqlite3_value_numeric_type(sqlite3_value*);
  4600 
  4601 /*
  4602 ** CAPI3REF: Finding The Subtype Of SQL Values
  4603 ** METHOD: sqlite3_value
  4604 **
  4605 ** The sqlite3_value_subtype(V) function returns the subtype for
  4606 ** an [application-defined SQL function] argument V.  The subtype
  4607 ** information can be used to pass a limited amount of context from
  4608 ** one SQL function to another.  Use the [sqlite3_result_subtype()]
  4609 ** routine to set the subtype for the return value of an SQL function.
  4610 **
  4611 ** SQLite makes no use of subtype itself.  It merely passes the subtype
  4612 ** from the result of one [application-defined SQL function] into the
  4613 ** input of another.
  4614 */
  4615 SQLITE_API unsigned int SQLITE_STDCALL sqlite3_value_subtype(sqlite3_value*);
  4616 
  4617 /*
  4618 ** CAPI3REF: Copy And Free SQL Values
  4619 ** METHOD: sqlite3_value
  4620 **
  4621 ** ^The sqlite3_value_dup(V) interface makes a copy of the [sqlite3_value]
  4622 ** object D and returns a pointer to that copy.  ^The [sqlite3_value] returned
  4623 ** is a [protected sqlite3_value] object even if the input is not.
  4624 ** ^The sqlite3_value_dup(V) interface returns NULL if V is NULL or if a
  4625 ** memory allocation fails.
  4626 **
  4627 ** ^The sqlite3_value_free(V) interface frees an [sqlite3_value] object
  4628 ** previously obtained from [sqlite3_value_dup()].  ^If V is a NULL pointer
  4629 ** then sqlite3_value_free(V) is a harmless no-op.
  4630 */
  4631 SQLITE_API sqlite3_value *SQLITE_STDCALL sqlite3_value_dup(const sqlite3_value*);
  4632 SQLITE_API void SQLITE_STDCALL sqlite3_value_free(sqlite3_value*);
  4633 
  4634 /*
  4635 ** CAPI3REF: Obtain Aggregate Function Context
  4636 ** METHOD: sqlite3_context
  4637 **
  4638 ** Implementations of aggregate SQL functions use this
  4639 ** routine to allocate memory for storing their state.
  4640 **
  4641 ** ^The first time the sqlite3_aggregate_context(C,N) routine is called 
  4642 ** for a particular aggregate function, SQLite
  4643 ** allocates N of memory, zeroes out that memory, and returns a pointer
  4644 ** to the new memory. ^On second and subsequent calls to
  4645 ** sqlite3_aggregate_context() for the same aggregate function instance,
  4646 ** the same buffer is returned.  Sqlite3_aggregate_context() is normally
  4647 ** called once for each invocation of the xStep callback and then one
  4648 ** last time when the xFinal callback is invoked.  ^(When no rows match
  4649 ** an aggregate query, the xStep() callback of the aggregate function
  4650 ** implementation is never called and xFinal() is called exactly once.
  4651 ** In those cases, sqlite3_aggregate_context() might be called for the
  4652 ** first time from within xFinal().)^
  4653 **
  4654 ** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer 
  4655 ** when first called if N is less than or equal to zero or if a memory
  4656 ** allocate error occurs.
  4657 **
  4658 ** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is
  4659 ** determined by the N parameter on first successful call.  Changing the
  4660 ** value of N in subsequent call to sqlite3_aggregate_context() within
  4661 ** the same aggregate function instance will not resize the memory
  4662 ** allocation.)^  Within the xFinal callback, it is customary to set
  4663 ** N=0 in calls to sqlite3_aggregate_context(C,N) so that no 
  4664 ** pointless memory allocations occur.
  4665 **
  4666 ** ^SQLite automatically frees the memory allocated by 
  4667 ** sqlite3_aggregate_context() when the aggregate query concludes.
  4668 **
  4669 ** The first parameter must be a copy of the
  4670 ** [sqlite3_context | SQL function context] that is the first parameter
  4671 ** to the xStep or xFinal callback routine that implements the aggregate
  4672 ** function.
  4673 **
  4674 ** This routine must be called from the same thread in which
  4675 ** the aggregate SQL function is running.
  4676 */
  4677 SQLITE_API void *SQLITE_STDCALL sqlite3_aggregate_context(sqlite3_context*, int nBytes);
  4678 
  4679 /*
  4680 ** CAPI3REF: User Data For Functions
  4681 ** METHOD: sqlite3_context
  4682 **
  4683 ** ^The sqlite3_user_data() interface returns a copy of
  4684 ** the pointer that was the pUserData parameter (the 5th parameter)
  4685 ** of the [sqlite3_create_function()]
  4686 ** and [sqlite3_create_function16()] routines that originally
  4687 ** registered the application defined function.
  4688 **
  4689 ** This routine must be called from the same thread in which
  4690 ** the application-defined function is running.
  4691 */
  4692 SQLITE_API void *SQLITE_STDCALL sqlite3_user_data(sqlite3_context*);
  4693 
  4694 /*
  4695 ** CAPI3REF: Database Connection For Functions
  4696 ** METHOD: sqlite3_context
  4697 **
  4698 ** ^The sqlite3_context_db_handle() interface returns a copy of
  4699 ** the pointer to the [database connection] (the 1st parameter)
  4700 ** of the [sqlite3_create_function()]
  4701 ** and [sqlite3_create_function16()] routines that originally
  4702 ** registered the application defined function.
  4703 */
  4704 SQLITE_API sqlite3 *SQLITE_STDCALL sqlite3_context_db_handle(sqlite3_context*);
  4705 
  4706 /*
  4707 ** CAPI3REF: Function Auxiliary Data
  4708 ** METHOD: sqlite3_context
  4709 **
  4710 ** These functions may be used by (non-aggregate) SQL functions to
  4711 ** associate metadata with argument values. If the same value is passed to
  4712 ** multiple invocations of the same SQL function during query execution, under
  4713 ** some circumstances the associated metadata may be preserved.  An example
  4714 ** of where this might be useful is in a regular-expression matching
  4715 ** function. The compiled version of the regular expression can be stored as
  4716 ** metadata associated with the pattern string.  
  4717 ** Then as long as the pattern string remains the same,
  4718 ** the compiled regular expression can be reused on multiple
  4719 ** invocations of the same function.
  4720 **
  4721 ** ^The sqlite3_get_auxdata() interface returns a pointer to the metadata
  4722 ** associated by the sqlite3_set_auxdata() function with the Nth argument
  4723 ** value to the application-defined function. ^If there is no metadata
  4724 ** associated with the function argument, this sqlite3_get_auxdata() interface
  4725 ** returns a NULL pointer.
  4726 **
  4727 ** ^The sqlite3_set_auxdata(C,N,P,X) interface saves P as metadata for the N-th
  4728 ** argument of the application-defined function.  ^Subsequent
  4729 ** calls to sqlite3_get_auxdata(C,N) return P from the most recent
  4730 ** sqlite3_set_auxdata(C,N,P,X) call if the metadata is still valid or
  4731 ** NULL if the metadata has been discarded.
  4732 ** ^After each call to sqlite3_set_auxdata(C,N,P,X) where X is not NULL,
  4733 ** SQLite will invoke the destructor function X with parameter P exactly
  4734 ** once, when the metadata is discarded.
  4735 ** SQLite is free to discard the metadata at any time, including: <ul>
  4736 ** <li> when the corresponding function parameter changes, or
  4737 ** <li> when [sqlite3_reset()] or [sqlite3_finalize()] is called for the
  4738 **      SQL statement, or
  4739 ** <li> when sqlite3_set_auxdata() is invoked again on the same parameter, or
  4740 ** <li> during the original sqlite3_set_auxdata() call when a memory 
  4741 **      allocation error occurs. </ul>)^
  4742 **
  4743 ** Note the last bullet in particular.  The destructor X in 
  4744 ** sqlite3_set_auxdata(C,N,P,X) might be called immediately, before the
  4745 ** sqlite3_set_auxdata() interface even returns.  Hence sqlite3_set_auxdata()
  4746 ** should be called near the end of the function implementation and the
  4747 ** function implementation should not make any use of P after
  4748 ** sqlite3_set_auxdata() has been called.
  4749 **
  4750 ** ^(In practice, metadata is preserved between function calls for
  4751 ** function parameters that are compile-time constants, including literal
  4752 ** values and [parameters] and expressions composed from the same.)^
  4753 **
  4754 ** These routines must be called from the same thread in which
  4755 ** the SQL function is running.
  4756 */
  4757 SQLITE_API void *SQLITE_STDCALL sqlite3_get_auxdata(sqlite3_context*, int N);
  4758 SQLITE_API void SQLITE_STDCALL sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));
  4759 
  4760 
  4761 /*
  4762 ** CAPI3REF: Constants Defining Special Destructor Behavior
  4763 **
  4764 ** These are special values for the destructor that is passed in as the
  4765 ** final argument to routines like [sqlite3_result_blob()].  ^If the destructor
  4766 ** argument is SQLITE_STATIC, it means that the content pointer is constant
  4767 ** and will never change.  It does not need to be destroyed.  ^The
  4768 ** SQLITE_TRANSIENT value means that the content will likely change in
  4769 ** the near future and that SQLite should make its own private copy of
  4770 ** the content before returning.
  4771 **
  4772 ** The typedef is necessary to work around problems in certain
  4773 ** C++ compilers.
  4774 */
  4775 typedef void (*sqlite3_destructor_type)(void*);
  4776 #define SQLITE_STATIC      ((sqlite3_destructor_type)0)
  4777 #define SQLITE_TRANSIENT   ((sqlite3_destructor_type)-1)
  4778 
  4779 /*
  4780 ** CAPI3REF: Setting The Result Of An SQL Function
  4781 ** METHOD: sqlite3_context
  4782 **
  4783 ** These routines are used by the xFunc or xFinal callbacks that
  4784 ** implement SQL functions and aggregates.  See
  4785 ** [sqlite3_create_function()] and [sqlite3_create_function16()]
  4786 ** for additional information.
  4787 **
  4788 ** These functions work very much like the [parameter binding] family of
  4789 ** functions used to bind values to host parameters in prepared statements.
  4790 ** Refer to the [SQL parameter] documentation for additional information.
  4791 **
  4792 ** ^The sqlite3_result_blob() interface sets the result from
  4793 ** an application-defined function to be the BLOB whose content is pointed
  4794 ** to by the second parameter and which is N bytes long where N is the
  4795 ** third parameter.
  4796 **
  4797 ** ^The sqlite3_result_zeroblob(C,N) and sqlite3_result_zeroblob64(C,N)
  4798 ** interfaces set the result of the application-defined function to be
  4799 ** a BLOB containing all zero bytes and N bytes in size.
  4800 **
  4801 ** ^The sqlite3_result_double() interface sets the result from
  4802 ** an application-defined function to be a floating point value specified
  4803 ** by its 2nd argument.
  4804 **
  4805 ** ^The sqlite3_result_error() and sqlite3_result_error16() functions
  4806 ** cause the implemented SQL function to throw an exception.
  4807 ** ^SQLite uses the string pointed to by the
  4808 ** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
  4809 ** as the text of an error message.  ^SQLite interprets the error
  4810 ** message string from sqlite3_result_error() as UTF-8. ^SQLite
  4811 ** interprets the string from sqlite3_result_error16() as UTF-16 in native
  4812 ** byte order.  ^If the third parameter to sqlite3_result_error()
  4813 ** or sqlite3_result_error16() is negative then SQLite takes as the error
  4814 ** message all text up through the first zero character.
  4815 ** ^If the third parameter to sqlite3_result_error() or
  4816 ** sqlite3_result_error16() is non-negative then SQLite takes that many
  4817 ** bytes (not characters) from the 2nd parameter as the error message.
  4818 ** ^The sqlite3_result_error() and sqlite3_result_error16()
  4819 ** routines make a private copy of the error message text before
  4820 ** they return.  Hence, the calling function can deallocate or
  4821 ** modify the text after they return without harm.
  4822 ** ^The sqlite3_result_error_code() function changes the error code
  4823 ** returned by SQLite as a result of an error in a function.  ^By default,
  4824 ** the error code is SQLITE_ERROR.  ^A subsequent call to sqlite3_result_error()
  4825 ** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
  4826 **
  4827 ** ^The sqlite3_result_error_toobig() interface causes SQLite to throw an
  4828 ** error indicating that a string or BLOB is too long to represent.
  4829 **
  4830 ** ^The sqlite3_result_error_nomem() interface causes SQLite to throw an
  4831 ** error indicating that a memory allocation failed.
  4832 **
  4833 ** ^The sqlite3_result_int() interface sets the return value
  4834 ** of the application-defined function to be the 32-bit signed integer
  4835 ** value given in the 2nd argument.
  4836 ** ^The sqlite3_result_int64() interface sets the return value
  4837 ** of the application-defined function to be the 64-bit signed integer
  4838 ** value given in the 2nd argument.
  4839 **
  4840 ** ^The sqlite3_result_null() interface sets the return value
  4841 ** of the application-defined function to be NULL.
  4842 **
  4843 ** ^The sqlite3_result_text(), sqlite3_result_text16(),
  4844 ** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
  4845 ** set the return value of the application-defined function to be
  4846 ** a text string which is represented as UTF-8, UTF-16 native byte order,
  4847 ** UTF-16 little endian, or UTF-16 big endian, respectively.
  4848 ** ^The sqlite3_result_text64() interface sets the return value of an
  4849 ** application-defined function to be a text string in an encoding
  4850 ** specified by the fifth (and last) parameter, which must be one
  4851 ** of [SQLITE_UTF8], [SQLITE_UTF16], [SQLITE_UTF16BE], or [SQLITE_UTF16LE].
  4852 ** ^SQLite takes the text result from the application from
  4853 ** the 2nd parameter of the sqlite3_result_text* interfaces.
  4854 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
  4855 ** is negative, then SQLite takes result text from the 2nd parameter
  4856 ** through the first zero character.
  4857 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
  4858 ** is non-negative, then as many bytes (not characters) of the text
  4859 ** pointed to by the 2nd parameter are taken as the application-defined
  4860 ** function result.  If the 3rd parameter is non-negative, then it
  4861 ** must be the byte offset into the string where the NUL terminator would
  4862 ** appear if the string where NUL terminated.  If any NUL characters occur
  4863 ** in the string at a byte offset that is less than the value of the 3rd
  4864 ** parameter, then the resulting string will contain embedded NULs and the
  4865 ** result of expressions operating on strings with embedded NULs is undefined.
  4866 ** ^If the 4th parameter to the sqlite3_result_text* interfaces
  4867 ** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
  4868 ** function as the destructor on the text or BLOB result when it has
  4869 ** finished using that result.
  4870 ** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
  4871 ** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
  4872 ** assumes that the text or BLOB result is in constant space and does not
  4873 ** copy the content of the parameter nor call a destructor on the content
  4874 ** when it has finished using that result.
  4875 ** ^If the 4th parameter to the sqlite3_result_text* interfaces
  4876 ** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
  4877 ** then SQLite makes a copy of the result into space obtained from
  4878 ** from [sqlite3_malloc()] before it returns.
  4879 **
  4880 ** ^The sqlite3_result_value() interface sets the result of
  4881 ** the application-defined function to be a copy of the
  4882 ** [unprotected sqlite3_value] object specified by the 2nd parameter.  ^The
  4883 ** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
  4884 ** so that the [sqlite3_value] specified in the parameter may change or
  4885 ** be deallocated after sqlite3_result_value() returns without harm.
  4886 ** ^A [protected sqlite3_value] object may always be used where an
  4887 ** [unprotected sqlite3_value] object is required, so either
  4888 ** kind of [sqlite3_value] object can be used with this interface.
  4889 **
  4890 ** If these routines are called from within the different thread
  4891 ** than the one containing the application-defined function that received
  4892 ** the [sqlite3_context] pointer, the results are undefined.
  4893 */
  4894 SQLITE_API void SQLITE_STDCALL sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
  4895 SQLITE_API void SQLITE_STDCALL sqlite3_result_blob64(sqlite3_context*,const void*,
  4896                            sqlite3_uint64,void(*)(void*));
  4897 SQLITE_API void SQLITE_STDCALL sqlite3_result_double(sqlite3_context*, double);
  4898 SQLITE_API void SQLITE_STDCALL sqlite3_result_error(sqlite3_context*, const char*, int);
  4899 SQLITE_API void SQLITE_STDCALL sqlite3_result_error16(sqlite3_context*, const void*, int);
  4900 SQLITE_API void SQLITE_STDCALL sqlite3_result_error_toobig(sqlite3_context*);
  4901 SQLITE_API void SQLITE_STDCALL sqlite3_result_error_nomem(sqlite3_context*);
  4902 SQLITE_API void SQLITE_STDCALL sqlite3_result_error_code(sqlite3_context*, int);
  4903 SQLITE_API void SQLITE_STDCALL sqlite3_result_int(sqlite3_context*, int);
  4904 SQLITE_API void SQLITE_STDCALL sqlite3_result_int64(sqlite3_context*, sqlite3_int64);
  4905 SQLITE_API void SQLITE_STDCALL sqlite3_result_null(sqlite3_context*);
  4906 SQLITE_API void SQLITE_STDCALL sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
  4907 SQLITE_API void SQLITE_STDCALL sqlite3_result_text64(sqlite3_context*, const char*,sqlite3_uint64,
  4908                            void(*)(void*), unsigned char encoding);
  4909 SQLITE_API void SQLITE_STDCALL sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
  4910 SQLITE_API void SQLITE_STDCALL sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
  4911 SQLITE_API void SQLITE_STDCALL sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
  4912 SQLITE_API void SQLITE_STDCALL sqlite3_result_value(sqlite3_context*, sqlite3_value*);
  4913 SQLITE_API void SQLITE_STDCALL sqlite3_result_zeroblob(sqlite3_context*, int n);
  4914 SQLITE_API int SQLITE_STDCALL sqlite3_result_zeroblob64(sqlite3_context*, sqlite3_uint64 n);
  4915 
  4916 
  4917 /*
  4918 ** CAPI3REF: Setting The Subtype Of An SQL Function
  4919 ** METHOD: sqlite3_context
  4920 **
  4921 ** The sqlite3_result_subtype(C,T) function causes the subtype of
  4922 ** the result from the [application-defined SQL function] with 
  4923 ** [sqlite3_context] C to be the value T.  Only the lower 8 bits 
  4924 ** of the subtype T are preserved in current versions of SQLite;
  4925 ** higher order bits are discarded.
  4926 ** The number of subtype bytes preserved by SQLite might increase
  4927 ** in future releases of SQLite.
  4928 */
  4929 SQLITE_API void SQLITE_STDCALL sqlite3_result_subtype(sqlite3_context*,unsigned int);
  4930 
  4931 /*
  4932 ** CAPI3REF: Define New Collating Sequences
  4933 ** METHOD: sqlite3
  4934 **
  4935 ** ^These functions add, remove, or modify a [collation] associated
  4936 ** with the [database connection] specified as the first argument.
  4937 **
  4938 ** ^The name of the collation is a UTF-8 string
  4939 ** for sqlite3_create_collation() and sqlite3_create_collation_v2()
  4940 ** and a UTF-16 string in native byte order for sqlite3_create_collation16().
  4941 ** ^Collation names that compare equal according to [sqlite3_strnicmp()] are
  4942 ** considered to be the same name.
  4943 **
  4944 ** ^(The third argument (eTextRep) must be one of the constants:
  4945 ** <ul>
  4946 ** <li> [SQLITE_UTF8],
  4947 ** <li> [SQLITE_UTF16LE],
  4948 ** <li> [SQLITE_UTF16BE],
  4949 ** <li> [SQLITE_UTF16], or
  4950 ** <li> [SQLITE_UTF16_ALIGNED].
  4951 ** </ul>)^
  4952 ** ^The eTextRep argument determines the encoding of strings passed
  4953 ** to the collating function callback, xCallback.
  4954 ** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep
  4955 ** force strings to be UTF16 with native byte order.
  4956 ** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin
  4957 ** on an even byte address.
  4958 **
  4959 ** ^The fourth argument, pArg, is an application data pointer that is passed
  4960 ** through as the first argument to the collating function callback.
  4961 **
  4962 ** ^The fifth argument, xCallback, is a pointer to the collating function.
  4963 ** ^Multiple collating functions can be registered using the same name but
  4964 ** with different eTextRep parameters and SQLite will use whichever
  4965 ** function requires the least amount of data transformation.
  4966 ** ^If the xCallback argument is NULL then the collating function is
  4967 ** deleted.  ^When all collating functions having the same name are deleted,
  4968 ** that collation is no longer usable.
  4969 **
  4970 ** ^The collating function callback is invoked with a copy of the pArg 
  4971 ** application data pointer and with two strings in the encoding specified
  4972 ** by the eTextRep argument.  The collating function must return an
  4973 ** integer that is negative, zero, or positive
  4974 ** if the first string is less than, equal to, or greater than the second,
  4975 ** respectively.  A collating function must always return the same answer
  4976 ** given the same inputs.  If two or more collating functions are registered
  4977 ** to the same collation name (using different eTextRep values) then all
  4978 ** must give an equivalent answer when invoked with equivalent strings.
  4979 ** The collating function must obey the following properties for all
  4980 ** strings A, B, and C:
  4981 **
  4982 ** <ol>
  4983 ** <li> If A==B then B==A.
  4984 ** <li> If A==B and B==C then A==C.
  4985 ** <li> If A&lt;B THEN B&gt;A.
  4986 ** <li> If A&lt;B and B&lt;C then A&lt;C.
  4987 ** </ol>
  4988 **
  4989 ** If a collating function fails any of the above constraints and that
  4990 ** collating function is  registered and used, then the behavior of SQLite
  4991 ** is undefined.
  4992 **
  4993 ** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation()
  4994 ** with the addition that the xDestroy callback is invoked on pArg when
  4995 ** the collating function is deleted.
  4996 ** ^Collating functions are deleted when they are overridden by later
  4997 ** calls to the collation creation functions or when the
  4998 ** [database connection] is closed using [sqlite3_close()].
  4999 **
  5000 ** ^The xDestroy callback is <u>not</u> called if the 
  5001 ** sqlite3_create_collation_v2() function fails.  Applications that invoke
  5002 ** sqlite3_create_collation_v2() with a non-NULL xDestroy argument should 
  5003 ** check the return code and dispose of the application data pointer
  5004 ** themselves rather than expecting SQLite to deal with it for them.
  5005 ** This is different from every other SQLite interface.  The inconsistency 
  5006 ** is unfortunate but cannot be changed without breaking backwards 
  5007 ** compatibility.
  5008 **
  5009 ** See also:  [sqlite3_collation_needed()] and [sqlite3_collation_needed16()].
  5010 */
  5011 SQLITE_API int SQLITE_STDCALL sqlite3_create_collation(
  5012   sqlite3*, 
  5013   const char *zName, 
  5014   int eTextRep, 
  5015   void *pArg,
  5016   int(*xCompare)(void*,int,const void*,int,const void*)
  5017 );
  5018 SQLITE_API int SQLITE_STDCALL sqlite3_create_collation_v2(
  5019   sqlite3*, 
  5020   const char *zName, 
  5021   int eTextRep, 
  5022   void *pArg,
  5023   int(*xCompare)(void*,int,const void*,int,const void*),
  5024   void(*xDestroy)(void*)
  5025 );
  5026 SQLITE_API int SQLITE_STDCALL sqlite3_create_collation16(
  5027   sqlite3*, 
  5028   const void *zName,
  5029   int eTextRep, 
  5030   void *pArg,
  5031   int(*xCompare)(void*,int,const void*,int,const void*)
  5032 );
  5033 
  5034 /*
  5035 ** CAPI3REF: Collation Needed Callbacks
  5036 ** METHOD: sqlite3
  5037 **
  5038 ** ^To avoid having to register all collation sequences before a database
  5039 ** can be used, a single callback function may be registered with the
  5040 ** [database connection] to be invoked whenever an undefined collation
  5041 ** sequence is required.
  5042 **
  5043 ** ^If the function is registered using the sqlite3_collation_needed() API,
  5044 ** then it is passed the names of undefined collation sequences as strings
  5045 ** encoded in UTF-8. ^If sqlite3_collation_needed16() is used,
  5046 ** the names are passed as UTF-16 in machine native byte order.
  5047 ** ^A call to either function replaces the existing collation-needed callback.
  5048 **
  5049 ** ^(When the callback is invoked, the first argument passed is a copy
  5050 ** of the second argument to sqlite3_collation_needed() or
  5051 ** sqlite3_collation_needed16().  The second argument is the database
  5052 ** connection.  The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
  5053 ** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
  5054 ** sequence function required.  The fourth parameter is the name of the
  5055 ** required collation sequence.)^
  5056 **
  5057 ** The callback function should register the desired collation using
  5058 ** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
  5059 ** [sqlite3_create_collation_v2()].
  5060 */
  5061 SQLITE_API int SQLITE_STDCALL sqlite3_collation_needed(
  5062   sqlite3*, 
  5063   void*, 
  5064   void(*)(void*,sqlite3*,int eTextRep,const char*)
  5065 );
  5066 SQLITE_API int SQLITE_STDCALL sqlite3_collation_needed16(
  5067   sqlite3*, 
  5068   void*,
  5069   void(*)(void*,sqlite3*,int eTextRep,const void*)
  5070 );
  5071 
  5072 #ifdef SQLITE_HAS_CODEC
  5073 /*
  5074 ** Specify the key for an encrypted database.  This routine should be
  5075 ** called right after sqlite3_open().
  5076 **
  5077 ** The code to implement this API is not available in the public release
  5078 ** of SQLite.
  5079 */
  5080 SQLITE_API int SQLITE_STDCALL sqlite3_key(
  5081   sqlite3 *db,                   /* Database to be rekeyed */
  5082   const void *pKey, int nKey     /* The key */
  5083 );
  5084 SQLITE_API int SQLITE_STDCALL sqlite3_key_v2(
  5085   sqlite3 *db,                   /* Database to be rekeyed */
  5086   const char *zDbName,           /* Name of the database */
  5087   const void *pKey, int nKey     /* The key */
  5088 );
  5089 
  5090 /*
  5091 ** Change the key on an open database.  If the current database is not
  5092 ** encrypted, this routine will encrypt it.  If pNew==0 or nNew==0, the
  5093 ** database is decrypted.
  5094 **
  5095 ** The code to implement this API is not available in the public release
  5096 ** of SQLite.
  5097 */
  5098 SQLITE_API int SQLITE_STDCALL sqlite3_rekey(
  5099   sqlite3 *db,                   /* Database to be rekeyed */
  5100   const void *pKey, int nKey     /* The new key */
  5101 );
  5102 SQLITE_API int SQLITE_STDCALL sqlite3_rekey_v2(
  5103   sqlite3 *db,                   /* Database to be rekeyed */
  5104   const char *zDbName,           /* Name of the database */
  5105   const void *pKey, int nKey     /* The new key */
  5106 );
  5107 
  5108 /*
  5109 ** Specify the activation key for a SEE database.  Unless 
  5110 ** activated, none of the SEE routines will work.
  5111 */
  5112 SQLITE_API void SQLITE_STDCALL sqlite3_activate_see(
  5113   const char *zPassPhrase        /* Activation phrase */
  5114 );
  5115 #endif
  5116 
  5117 #ifdef SQLITE_ENABLE_CEROD
  5118 /*
  5119 ** Specify the activation key for a CEROD database.  Unless 
  5120 ** activated, none of the CEROD routines will work.
  5121 */
  5122 SQLITE_API void SQLITE_STDCALL sqlite3_activate_cerod(
  5123   const char *zPassPhrase        /* Activation phrase */
  5124 );
  5125 #endif
  5126 
  5127 /*
  5128 ** CAPI3REF: Suspend Execution For A Short Time
  5129 **
  5130 ** The sqlite3_sleep() function causes the current thread to suspend execution
  5131 ** for at least a number of milliseconds specified in its parameter.
  5132 **
  5133 ** If the operating system does not support sleep requests with
  5134 ** millisecond time resolution, then the time will be rounded up to
  5135 ** the nearest second. The number of milliseconds of sleep actually
  5136 ** requested from the operating system is returned.
  5137 **
  5138 ** ^SQLite implements this interface by calling the xSleep()
  5139 ** method of the default [sqlite3_vfs] object.  If the xSleep() method
  5140 ** of the default VFS is not implemented correctly, or not implemented at
  5141 ** all, then the behavior of sqlite3_sleep() may deviate from the description
  5142 ** in the previous paragraphs.
  5143 */
  5144 SQLITE_API int SQLITE_STDCALL sqlite3_sleep(int);
  5145 
  5146 /*
  5147 ** CAPI3REF: Name Of The Folder Holding Temporary Files
  5148 **
  5149 ** ^(If this global variable is made to point to a string which is
  5150 ** the name of a folder (a.k.a. directory), then all temporary files
  5151 ** created by SQLite when using a built-in [sqlite3_vfs | VFS]
  5152 ** will be placed in that directory.)^  ^If this variable
  5153 ** is a NULL pointer, then SQLite performs a search for an appropriate
  5154 ** temporary file directory.
  5155 **
  5156 ** Applications are strongly discouraged from using this global variable.
  5157 ** It is required to set a temporary folder on Windows Runtime (WinRT).
  5158 ** But for all other platforms, it is highly recommended that applications
  5159 ** neither read nor write this variable.  This global variable is a relic
  5160 ** that exists for backwards compatibility of legacy applications and should
  5161 ** be avoided in new projects.
  5162 **
  5163 ** It is not safe to read or modify this variable in more than one
  5164 ** thread at a time.  It is not safe to read or modify this variable
  5165 ** if a [database connection] is being used at the same time in a separate
  5166 ** thread.
  5167 ** It is intended that this variable be set once
  5168 ** as part of process initialization and before any SQLite interface
  5169 ** routines have been called and that this variable remain unchanged
  5170 ** thereafter.
  5171 **
  5172 ** ^The [temp_store_directory pragma] may modify this variable and cause
  5173 ** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
  5174 ** the [temp_store_directory pragma] always assumes that any string
  5175 ** that this variable points to is held in memory obtained from 
  5176 ** [sqlite3_malloc] and the pragma may attempt to free that memory
  5177 ** using [sqlite3_free].
  5178 ** Hence, if this variable is modified directly, either it should be
  5179 ** made NULL or made to point to memory obtained from [sqlite3_malloc]
  5180 ** or else the use of the [temp_store_directory pragma] should be avoided.
  5181 ** Except when requested by the [temp_store_directory pragma], SQLite
  5182 ** does not free the memory that sqlite3_temp_directory points to.  If
  5183 ** the application wants that memory to be freed, it must do
  5184 ** so itself, taking care to only do so after all [database connection]
  5185 ** objects have been destroyed.
  5186 **
  5187 ** <b>Note to Windows Runtime users:</b>  The temporary directory must be set
  5188 ** prior to calling [sqlite3_open] or [sqlite3_open_v2].  Otherwise, various
  5189 ** features that require the use of temporary files may fail.  Here is an
  5190 ** example of how to do this using C++ with the Windows Runtime:
  5191 **
  5192 ** <blockquote><pre>
  5193 ** LPCWSTR zPath = Windows::Storage::ApplicationData::Current->
  5194 ** &nbsp;     TemporaryFolder->Path->Data();
  5195 ** char zPathBuf&#91;MAX_PATH + 1&#93;;
  5196 ** memset(zPathBuf, 0, sizeof(zPathBuf));
  5197 ** WideCharToMultiByte(CP_UTF8, 0, zPath, -1, zPathBuf, sizeof(zPathBuf),
  5198 ** &nbsp;     NULL, NULL);
  5199 ** sqlite3_temp_directory = sqlite3_mprintf("%s", zPathBuf);
  5200 ** </pre></blockquote>
  5201 */
  5202 SQLITE_API char *sqlite3_temp_directory;
  5203 
  5204 /*
  5205 ** CAPI3REF: Name Of The Folder Holding Database Files
  5206 **
  5207 ** ^(If this global variable is made to point to a string which is
  5208 ** the name of a folder (a.k.a. directory), then all database files
  5209 ** specified with a relative pathname and created or accessed by
  5210 ** SQLite when using a built-in windows [sqlite3_vfs | VFS] will be assumed
  5211 ** to be relative to that directory.)^ ^If this variable is a NULL
  5212 ** pointer, then SQLite assumes that all database files specified
  5213 ** with a relative pathname are relative to the current directory
  5214 ** for the process.  Only the windows VFS makes use of this global
  5215 ** variable; it is ignored by the unix VFS.
  5216 **
  5217 ** Changing the value of this variable while a database connection is
  5218 ** open can result in a corrupt database.
  5219 **
  5220 ** It is not safe to read or modify this variable in more than one
  5221 ** thread at a time.  It is not safe to read or modify this variable
  5222 ** if a [database connection] is being used at the same time in a separate
  5223 ** thread.
  5224 ** It is intended that this variable be set once
  5225 ** as part of process initialization and before any SQLite interface
  5226 ** routines have been called and that this variable remain unchanged
  5227 ** thereafter.
  5228 **
  5229 ** ^The [data_store_directory pragma] may modify this variable and cause
  5230 ** it to point to memory obtained from [sqlite3_malloc].  ^Furthermore,
  5231 ** the [data_store_directory pragma] always assumes that any string
  5232 ** that this variable points to is held in memory obtained from 
  5233 ** [sqlite3_malloc] and the pragma may attempt to free that memory
  5234 ** using [sqlite3_free].
  5235 ** Hence, if this variable is modified directly, either it should be
  5236 ** made NULL or made to point to memory obtained from [sqlite3_malloc]
  5237 ** or else the use of the [data_store_directory pragma] should be avoided.
  5238 */
  5239 SQLITE_API char *sqlite3_data_directory;
  5240 
  5241 /*
  5242 ** CAPI3REF: Test For Auto-Commit Mode
  5243 ** KEYWORDS: {autocommit mode}
  5244 ** METHOD: sqlite3
  5245 **
  5246 ** ^The sqlite3_get_autocommit() interface returns non-zero or
  5247 ** zero if the given database connection is or is not in autocommit mode,
  5248 ** respectively.  ^Autocommit mode is on by default.
  5249 ** ^Autocommit mode is disabled by a [BEGIN] statement.
  5250 ** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
  5251 **
  5252 ** If certain kinds of errors occur on a statement within a multi-statement
  5253 ** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
  5254 ** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the
  5255 ** transaction might be rolled back automatically.  The only way to
  5256 ** find out whether SQLite automatically rolled back the transaction after
  5257 ** an error is to use this function.
  5258 **
  5259 ** If another thread changes the autocommit status of the database
  5260 ** connection while this routine is running, then the return value
  5261 ** is undefined.
  5262 */
  5263 SQLITE_API int SQLITE_STDCALL sqlite3_get_autocommit(sqlite3*);
  5264 
  5265 /*
  5266 ** CAPI3REF: Find The Database Handle Of A Prepared Statement
  5267 ** METHOD: sqlite3_stmt
  5268 **
  5269 ** ^The sqlite3_db_handle interface returns the [database connection] handle
  5270 ** to which a [prepared statement] belongs.  ^The [database connection]
  5271 ** returned by sqlite3_db_handle is the same [database connection]
  5272 ** that was the first argument
  5273 ** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
  5274 ** create the statement in the first place.
  5275 */
  5276 SQLITE_API sqlite3 *SQLITE_STDCALL sqlite3_db_handle(sqlite3_stmt*);
  5277 
  5278 /*
  5279 ** CAPI3REF: Return The Filename For A Database Connection
  5280 ** METHOD: sqlite3
  5281 **
  5282 ** ^The sqlite3_db_filename(D,N) interface returns a pointer to a filename
  5283 ** associated with database N of connection D.  ^The main database file
  5284 ** has the name "main".  If there is no attached database N on the database
  5285 ** connection D, or if database N is a temporary or in-memory database, then
  5286 ** a NULL pointer is returned.
  5287 **
  5288 ** ^The filename returned by this function is the output of the
  5289 ** xFullPathname method of the [VFS].  ^In other words, the filename
  5290 ** will be an absolute pathname, even if the filename used
  5291 ** to open the database originally was a URI or relative pathname.
  5292 */
  5293 SQLITE_API const char *SQLITE_STDCALL sqlite3_db_filename(sqlite3 *db, const char *zDbName);
  5294 
  5295 /*
  5296 ** CAPI3REF: Determine if a database is read-only
  5297 ** METHOD: sqlite3
  5298 **
  5299 ** ^The sqlite3_db_readonly(D,N) interface returns 1 if the database N
  5300 ** of connection D is read-only, 0 if it is read/write, or -1 if N is not
  5301 ** the name of a database on connection D.
  5302 */
  5303 SQLITE_API int SQLITE_STDCALL sqlite3_db_readonly(sqlite3 *db, const char *zDbName);
  5304 
  5305 /*
  5306 ** CAPI3REF: Find the next prepared statement
  5307 ** METHOD: sqlite3
  5308 **
  5309 ** ^This interface returns a pointer to the next [prepared statement] after
  5310 ** pStmt associated with the [database connection] pDb.  ^If pStmt is NULL
  5311 ** then this interface returns a pointer to the first prepared statement
  5312 ** associated with the database connection pDb.  ^If no prepared statement
  5313 ** satisfies the conditions of this routine, it returns NULL.
  5314 **
  5315 ** The [database connection] pointer D in a call to
  5316 ** [sqlite3_next_stmt(D,S)] must refer to an open database
  5317 ** connection and in particular must not be a NULL pointer.
  5318 */
  5319 SQLITE_API sqlite3_stmt *SQLITE_STDCALL sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);
  5320 
  5321 /*
  5322 ** CAPI3REF: Commit And Rollback Notification Callbacks
  5323 ** METHOD: sqlite3
  5324 **
  5325 ** ^The sqlite3_commit_hook() interface registers a callback
  5326 ** function to be invoked whenever a transaction is [COMMIT | committed].
  5327 ** ^Any callback set by a previous call to sqlite3_commit_hook()
  5328 ** for the same database connection is overridden.
  5329 ** ^The sqlite3_rollback_hook() interface registers a callback
  5330 ** function to be invoked whenever a transaction is [ROLLBACK | rolled back].
  5331 ** ^Any callback set by a previous call to sqlite3_rollback_hook()
  5332 ** for the same database connection is overridden.
  5333 ** ^The pArg argument is passed through to the callback.
  5334 ** ^If the callback on a commit hook function returns non-zero,
  5335 ** then the commit is converted into a rollback.
  5336 **
  5337 ** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions
  5338 ** return the P argument from the previous call of the same function
  5339 ** on the same [database connection] D, or NULL for
  5340 ** the first call for each function on D.
  5341 **
  5342 ** The commit and rollback hook callbacks are not reentrant.
  5343 ** The callback implementation must not do anything that will modify
  5344 ** the database connection that invoked the callback.  Any actions
  5345 ** to modify the database connection must be deferred until after the
  5346 ** completion of the [sqlite3_step()] call that triggered the commit
  5347 ** or rollback hook in the first place.
  5348 ** Note that running any other SQL statements, including SELECT statements,
  5349 ** or merely calling [sqlite3_prepare_v2()] and [sqlite3_step()] will modify
  5350 ** the database connections for the meaning of "modify" in this paragraph.
  5351 **
  5352 ** ^Registering a NULL function disables the callback.
  5353 **
  5354 ** ^When the commit hook callback routine returns zero, the [COMMIT]
  5355 ** operation is allowed to continue normally.  ^If the commit hook
  5356 ** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].
  5357 ** ^The rollback hook is invoked on a rollback that results from a commit
  5358 ** hook returning non-zero, just as it would be with any other rollback.
  5359 **
  5360 ** ^For the purposes of this API, a transaction is said to have been
  5361 ** rolled back if an explicit "ROLLBACK" statement is executed, or
  5362 ** an error or constraint causes an implicit rollback to occur.
  5363 ** ^The rollback callback is not invoked if a transaction is
  5364 ** automatically rolled back because the database connection is closed.
  5365 **
  5366 ** See also the [sqlite3_update_hook()] interface.
  5367 */
  5368 SQLITE_API void *SQLITE_STDCALL sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
  5369 SQLITE_API void *SQLITE_STDCALL sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
  5370 
  5371 /*
  5372 ** CAPI3REF: Data Change Notification Callbacks
  5373 ** METHOD: sqlite3
  5374 **
  5375 ** ^The sqlite3_update_hook() interface registers a callback function
  5376 ** with the [database connection] identified by the first argument
  5377 ** to be invoked whenever a row is updated, inserted or deleted in
  5378 ** a rowid table.
  5379 ** ^Any callback set by a previous call to this function
  5380 ** for the same database connection is overridden.
  5381 **
  5382 ** ^The second argument is a pointer to the function to invoke when a
  5383 ** row is updated, inserted or deleted in a rowid table.
  5384 ** ^The first argument to the callback is a copy of the third argument
  5385 ** to sqlite3_update_hook().
  5386 ** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
  5387 ** or [SQLITE_UPDATE], depending on the operation that caused the callback
  5388 ** to be invoked.
  5389 ** ^The third and fourth arguments to the callback contain pointers to the
  5390 ** database and table name containing the affected row.
  5391 ** ^The final callback parameter is the [rowid] of the row.
  5392 ** ^In the case of an update, this is the [rowid] after the update takes place.
  5393 **
  5394 ** ^(The update hook is not invoked when internal system tables are
  5395 ** modified (i.e. sqlite_master and sqlite_sequence).)^
  5396 ** ^The update hook is not invoked when [WITHOUT ROWID] tables are modified.
  5397 **
  5398 ** ^In the current implementation, the update hook
  5399 ** is not invoked when duplication rows are deleted because of an
  5400 ** [ON CONFLICT | ON CONFLICT REPLACE] clause.  ^Nor is the update hook
  5401 ** invoked when rows are deleted using the [truncate optimization].
  5402 ** The exceptions defined in this paragraph might change in a future
  5403 ** release of SQLite.
  5404 **
  5405 ** The update hook implementation must not do anything that will modify
  5406 ** the database connection that invoked the update hook.  Any actions
  5407 ** to modify the database connection must be deferred until after the
  5408 ** completion of the [sqlite3_step()] call that triggered the update hook.
  5409 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
  5410 ** database connections for the meaning of "modify" in this paragraph.
  5411 **
  5412 ** ^The sqlite3_update_hook(D,C,P) function
  5413 ** returns the P argument from the previous call
  5414 ** on the same [database connection] D, or NULL for
  5415 ** the first call on D.
  5416 **
  5417 ** See also the [sqlite3_commit_hook()] and [sqlite3_rollback_hook()]
  5418 ** interfaces.
  5419 */
  5420 SQLITE_API void *SQLITE_STDCALL sqlite3_update_hook(
  5421   sqlite3*, 
  5422   void(*)(void *,int ,char const *,char const *,sqlite3_int64),
  5423   void*
  5424 );
  5425 
  5426 /*
  5427 ** CAPI3REF: Enable Or Disable Shared Pager Cache
  5428 **
  5429 ** ^(This routine enables or disables the sharing of the database cache
  5430 ** and schema data structures between [database connection | connections]
  5431 ** to the same database. Sharing is enabled if the argument is true
  5432 ** and disabled if the argument is false.)^
  5433 **
  5434 ** ^Cache sharing is enabled and disabled for an entire process.
  5435 ** This is a change as of SQLite version 3.5.0. In prior versions of SQLite,
  5436 ** sharing was enabled or disabled for each thread separately.
  5437 **
  5438 ** ^(The cache sharing mode set by this interface effects all subsequent
  5439 ** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
  5440 ** Existing database connections continue use the sharing mode
  5441 ** that was in effect at the time they were opened.)^
  5442 **
  5443 ** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
  5444 ** successfully.  An [error code] is returned otherwise.)^
  5445 **
  5446 ** ^Shared cache is disabled by default. But this might change in
  5447 ** future releases of SQLite.  Applications that care about shared
  5448 ** cache setting should set it explicitly.
  5449 **
  5450 ** Note: This method is disabled on MacOS X 10.7 and iOS version 5.0
  5451 ** and will always return SQLITE_MISUSE. On those systems, 
  5452 ** shared cache mode should be enabled per-database connection via 
  5453 ** [sqlite3_open_v2()] with [SQLITE_OPEN_SHAREDCACHE].
  5454 **
  5455 ** This interface is threadsafe on processors where writing a
  5456 ** 32-bit integer is atomic.
  5457 **
  5458 ** See Also:  [SQLite Shared-Cache Mode]
  5459 */
  5460 SQLITE_API int SQLITE_STDCALL sqlite3_enable_shared_cache(int);
  5461 
  5462 /*
  5463 ** CAPI3REF: Attempt To Free Heap Memory
  5464 **
  5465 ** ^The sqlite3_release_memory() interface attempts to free N bytes
  5466 ** of heap memory by deallocating non-essential memory allocations
  5467 ** held by the database library.   Memory used to cache database
  5468 ** pages to improve performance is an example of non-essential memory.
  5469 ** ^sqlite3_release_memory() returns the number of bytes actually freed,
  5470 ** which might be more or less than the amount requested.
  5471 ** ^The sqlite3_release_memory() routine is a no-op returning zero
  5472 ** if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT].
  5473 **
  5474 ** See also: [sqlite3_db_release_memory()]
  5475 */
  5476 SQLITE_API int SQLITE_STDCALL sqlite3_release_memory(int);
  5477 
  5478 /*
  5479 ** CAPI3REF: Free Memory Used By A Database Connection
  5480 ** METHOD: sqlite3
  5481 **
  5482 ** ^The sqlite3_db_release_memory(D) interface attempts to free as much heap
  5483 ** memory as possible from database connection D. Unlike the
  5484 ** [sqlite3_release_memory()] interface, this interface is in effect even
  5485 ** when the [SQLITE_ENABLE_MEMORY_MANAGEMENT] compile-time option is
  5486 ** omitted.
  5487 **
  5488 ** See also: [sqlite3_release_memory()]
  5489 */
  5490 SQLITE_API int SQLITE_STDCALL sqlite3_db_release_memory(sqlite3*);
  5491 
  5492 /*
  5493 ** CAPI3REF: Impose A Limit On Heap Size
  5494 **
  5495 ** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the
  5496 ** soft limit on the amount of heap memory that may be allocated by SQLite.
  5497 ** ^SQLite strives to keep heap memory utilization below the soft heap
  5498 ** limit by reducing the number of pages held in the page cache
  5499 ** as heap memory usages approaches the limit.
  5500 ** ^The soft heap limit is "soft" because even though SQLite strives to stay
  5501 ** below the limit, it will exceed the limit rather than generate
  5502 ** an [SQLITE_NOMEM] error.  In other words, the soft heap limit 
  5503 ** is advisory only.
  5504 **
  5505 ** ^The return value from sqlite3_soft_heap_limit64() is the size of
  5506 ** the soft heap limit prior to the call, or negative in the case of an
  5507 ** error.  ^If the argument N is negative
  5508 ** then no change is made to the soft heap limit.  Hence, the current
  5509 ** size of the soft heap limit can be determined by invoking
  5510 ** sqlite3_soft_heap_limit64() with a negative argument.
  5511 **
  5512 ** ^If the argument N is zero then the soft heap limit is disabled.
  5513 **
  5514 ** ^(The soft heap limit is not enforced in the current implementation
  5515 ** if one or more of following conditions are true:
  5516 **
  5517 ** <ul>
  5518 ** <li> The soft heap limit is set to zero.
  5519 ** <li> Memory accounting is disabled using a combination of the
  5520 **      [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
  5521 **      the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
  5522 ** <li> An alternative page cache implementation is specified using
  5523 **      [sqlite3_config]([SQLITE_CONFIG_PCACHE2],...).
  5524 ** <li> The page cache allocates from its own memory pool supplied
  5525 **      by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than
  5526 **      from the heap.
  5527 ** </ul>)^
  5528 **
  5529 ** Beginning with SQLite version 3.7.3, the soft heap limit is enforced
  5530 ** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]
  5531 ** compile-time option is invoked.  With [SQLITE_ENABLE_MEMORY_MANAGEMENT],
  5532 ** the soft heap limit is enforced on every memory allocation.  Without
  5533 ** [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced
  5534 ** when memory is allocated by the page cache.  Testing suggests that because
  5535 ** the page cache is the predominate memory user in SQLite, most
  5536 ** applications will achieve adequate soft heap limit enforcement without
  5537 ** the use of [SQLITE_ENABLE_MEMORY_MANAGEMENT].
  5538 **
  5539 ** The circumstances under which SQLite will enforce the soft heap limit may
  5540 ** changes in future releases of SQLite.
  5541 */
  5542 SQLITE_API sqlite3_int64 SQLITE_STDCALL sqlite3_soft_heap_limit64(sqlite3_int64 N);
  5543 
  5544 /*
  5545 ** CAPI3REF: Deprecated Soft Heap Limit Interface
  5546 ** DEPRECATED
  5547 **
  5548 ** This is a deprecated version of the [sqlite3_soft_heap_limit64()]
  5549 ** interface.  This routine is provided for historical compatibility
  5550 ** only.  All new applications should use the
  5551 ** [sqlite3_soft_heap_limit64()] interface rather than this one.
  5552 */
  5553 SQLITE_API SQLITE_DEPRECATED void SQLITE_STDCALL sqlite3_soft_heap_limit(int N);
  5554 
  5555 
  5556 /*
  5557 ** CAPI3REF: Extract Metadata About A Column Of A Table
  5558 ** METHOD: sqlite3
  5559 **
  5560 ** ^(The sqlite3_table_column_metadata(X,D,T,C,....) routine returns
  5561 ** information about column C of table T in database D
  5562 ** on [database connection] X.)^  ^The sqlite3_table_column_metadata()
  5563 ** interface returns SQLITE_OK and fills in the non-NULL pointers in
  5564 ** the final five arguments with appropriate values if the specified
  5565 ** column exists.  ^The sqlite3_table_column_metadata() interface returns
  5566 ** SQLITE_ERROR and if the specified column does not exist.
  5567 ** ^If the column-name parameter to sqlite3_table_column_metadata() is a
  5568 ** NULL pointer, then this routine simply checks for the existance of the
  5569 ** table and returns SQLITE_OK if the table exists and SQLITE_ERROR if it
  5570 ** does not.
  5571 **
  5572 ** ^The column is identified by the second, third and fourth parameters to
  5573 ** this function. ^(The second parameter is either the name of the database
  5574 ** (i.e. "main", "temp", or an attached database) containing the specified
  5575 ** table or NULL.)^ ^If it is NULL, then all attached databases are searched
  5576 ** for the table using the same algorithm used by the database engine to
  5577 ** resolve unqualified table references.
  5578 **
  5579 ** ^The third and fourth parameters to this function are the table and column
  5580 ** name of the desired column, respectively.
  5581 **
  5582 ** ^Metadata is returned by writing to the memory locations passed as the 5th
  5583 ** and subsequent parameters to this function. ^Any of these arguments may be
  5584 ** NULL, in which case the corresponding element of metadata is omitted.
  5585 **
  5586 ** ^(<blockquote>
  5587 ** <table border="1">
  5588 ** <tr><th> Parameter <th> Output<br>Type <th>  Description
  5589 **
  5590 ** <tr><td> 5th <td> const char* <td> Data type
  5591 ** <tr><td> 6th <td> const char* <td> Name of default collation sequence
  5592 ** <tr><td> 7th <td> int         <td> True if column has a NOT NULL constraint
  5593 ** <tr><td> 8th <td> int         <td> True if column is part of the PRIMARY KEY
  5594 ** <tr><td> 9th <td> int         <td> True if column is [AUTOINCREMENT]
  5595 ** </table>
  5596 ** </blockquote>)^
  5597 **
  5598 ** ^The memory pointed to by the character pointers returned for the
  5599 ** declaration type and collation sequence is valid until the next
  5600 ** call to any SQLite API function.
  5601 **
  5602 ** ^If the specified table is actually a view, an [error code] is returned.
  5603 **
  5604 ** ^If the specified column is "rowid", "oid" or "_rowid_" and the table 
  5605 ** is not a [WITHOUT ROWID] table and an
  5606 ** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
  5607 ** parameters are set for the explicitly declared column. ^(If there is no
  5608 ** [INTEGER PRIMARY KEY] column, then the outputs
  5609 ** for the [rowid] are set as follows:
  5610 **
  5611 ** <pre>
  5612 **     data type: "INTEGER"
  5613 **     collation sequence: "BINARY"
  5614 **     not null: 0
  5615 **     primary key: 1
  5616 **     auto increment: 0
  5617 ** </pre>)^
  5618 **
  5619 ** ^This function causes all database schemas to be read from disk and
  5620 ** parsed, if that has not already been done, and returns an error if
  5621 ** any errors are encountered while loading the schema.
  5622 */
  5623 SQLITE_API int SQLITE_STDCALL sqlite3_table_column_metadata(
  5624   sqlite3 *db,                /* Connection handle */
  5625   const char *zDbName,        /* Database name or NULL */
  5626   const char *zTableName,     /* Table name */
  5627   const char *zColumnName,    /* Column name */
  5628   char const **pzDataType,    /* OUTPUT: Declared data type */
  5629   char const **pzCollSeq,     /* OUTPUT: Collation sequence name */
  5630   int *pNotNull,              /* OUTPUT: True if NOT NULL constraint exists */
  5631   int *pPrimaryKey,           /* OUTPUT: True if column part of PK */
  5632   int *pAutoinc               /* OUTPUT: True if column is auto-increment */
  5633 );
  5634 
  5635 /*
  5636 ** CAPI3REF: Load An Extension
  5637 ** METHOD: sqlite3
  5638 **
  5639 ** ^This interface loads an SQLite extension library from the named file.
  5640 **
  5641 ** ^The sqlite3_load_extension() interface attempts to load an
  5642 ** [SQLite extension] library contained in the file zFile.  If
  5643 ** the file cannot be loaded directly, attempts are made to load
  5644 ** with various operating-system specific extensions added.
  5645 ** So for example, if "samplelib" cannot be loaded, then names like
  5646 ** "samplelib.so" or "samplelib.dylib" or "samplelib.dll" might
  5647 ** be tried also.
  5648 **
  5649 ** ^The entry point is zProc.
  5650 ** ^(zProc may be 0, in which case SQLite will try to come up with an
  5651 ** entry point name on its own.  It first tries "sqlite3_extension_init".
  5652 ** If that does not work, it constructs a name "sqlite3_X_init" where the
  5653 ** X is consists of the lower-case equivalent of all ASCII alphabetic
  5654 ** characters in the filename from the last "/" to the first following
  5655 ** "." and omitting any initial "lib".)^
  5656 ** ^The sqlite3_load_extension() interface returns
  5657 ** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
  5658 ** ^If an error occurs and pzErrMsg is not 0, then the
  5659 ** [sqlite3_load_extension()] interface shall attempt to
  5660 ** fill *pzErrMsg with error message text stored in memory
  5661 ** obtained from [sqlite3_malloc()]. The calling function
  5662 ** should free this memory by calling [sqlite3_free()].
  5663 **
  5664 ** ^Extension loading must be enabled using
  5665 ** [sqlite3_enable_load_extension()] prior to calling this API,
  5666 ** otherwise an error will be returned.
  5667 **
  5668 ** See also the [load_extension() SQL function].
  5669 */
  5670 SQLITE_API int SQLITE_STDCALL sqlite3_load_extension(
  5671   sqlite3 *db,          /* Load the extension into this database connection */
  5672   const char *zFile,    /* Name of the shared library containing extension */
  5673   const char *zProc,    /* Entry point.  Derived from zFile if 0 */
  5674   char **pzErrMsg       /* Put error message here if not 0 */
  5675 );
  5676 
  5677 /*
  5678 ** CAPI3REF: Enable Or Disable Extension Loading
  5679 ** METHOD: sqlite3
  5680 **
  5681 ** ^So as not to open security holes in older applications that are
  5682 ** unprepared to deal with [extension loading], and as a means of disabling
  5683 ** [extension loading] while evaluating user-entered SQL, the following API
  5684 ** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
  5685 **
  5686 ** ^Extension loading is off by default.
  5687 ** ^Call the sqlite3_enable_load_extension() routine with onoff==1
  5688 ** to turn extension loading on and call it with onoff==0 to turn
  5689 ** it back off again.
  5690 */
  5691 SQLITE_API int SQLITE_STDCALL sqlite3_enable_load_extension(sqlite3 *db, int onoff);
  5692 
  5693 /*
  5694 ** CAPI3REF: Automatically Load Statically Linked Extensions
  5695 **
  5696 ** ^This interface causes the xEntryPoint() function to be invoked for
  5697 ** each new [database connection] that is created.  The idea here is that
  5698 ** xEntryPoint() is the entry point for a statically linked [SQLite extension]
  5699 ** that is to be automatically loaded into all new database connections.
  5700 **
  5701 ** ^(Even though the function prototype shows that xEntryPoint() takes
  5702 ** no arguments and returns void, SQLite invokes xEntryPoint() with three
  5703 ** arguments and expects and integer result as if the signature of the
  5704 ** entry point where as follows:
  5705 **
  5706 ** <blockquote><pre>
  5707 ** &nbsp;  int xEntryPoint(
  5708 ** &nbsp;    sqlite3 *db,
  5709 ** &nbsp;    const char **pzErrMsg,
  5710 ** &nbsp;    const struct sqlite3_api_routines *pThunk
  5711 ** &nbsp;  );
  5712 ** </pre></blockquote>)^
  5713 **
  5714 ** If the xEntryPoint routine encounters an error, it should make *pzErrMsg
  5715 ** point to an appropriate error message (obtained from [sqlite3_mprintf()])
  5716 ** and return an appropriate [error code].  ^SQLite ensures that *pzErrMsg
  5717 ** is NULL before calling the xEntryPoint().  ^SQLite will invoke
  5718 ** [sqlite3_free()] on *pzErrMsg after xEntryPoint() returns.  ^If any
  5719 ** xEntryPoint() returns an error, the [sqlite3_open()], [sqlite3_open16()],
  5720 ** or [sqlite3_open_v2()] call that provoked the xEntryPoint() will fail.
  5721 **
  5722 ** ^Calling sqlite3_auto_extension(X) with an entry point X that is already
  5723 ** on the list of automatic extensions is a harmless no-op. ^No entry point
  5724 ** will be called more than once for each database connection that is opened.
  5725 **
  5726 ** See also: [sqlite3_reset_auto_extension()]
  5727 ** and [sqlite3_cancel_auto_extension()]
  5728 */
  5729 SQLITE_API int SQLITE_STDCALL sqlite3_auto_extension(void (*xEntryPoint)(void));
  5730 
  5731 /*
  5732 ** CAPI3REF: Cancel Automatic Extension Loading
  5733 **
  5734 ** ^The [sqlite3_cancel_auto_extension(X)] interface unregisters the
  5735 ** initialization routine X that was registered using a prior call to
  5736 ** [sqlite3_auto_extension(X)].  ^The [sqlite3_cancel_auto_extension(X)]
  5737 ** routine returns 1 if initialization routine X was successfully 
  5738 ** unregistered and it returns 0 if X was not on the list of initialization
  5739 ** routines.
  5740 */
  5741 SQLITE_API int SQLITE_STDCALL sqlite3_cancel_auto_extension(void (*xEntryPoint)(void));
  5742 
  5743 /*
  5744 ** CAPI3REF: Reset Automatic Extension Loading
  5745 **
  5746 ** ^This interface disables all automatic extensions previously
  5747 ** registered using [sqlite3_auto_extension()].
  5748 */
  5749 SQLITE_API void SQLITE_STDCALL sqlite3_reset_auto_extension(void);
  5750 
  5751 /*
  5752 ** The interface to the virtual-table mechanism is currently considered
  5753 ** to be experimental.  The interface might change in incompatible ways.
  5754 ** If this is a problem for you, do not use the interface at this time.
  5755 **
  5756 ** When the virtual-table mechanism stabilizes, we will declare the
  5757 ** interface fixed, support it indefinitely, and remove this comment.
  5758 */
  5759 
  5760 /*
  5761 ** Structures used by the virtual table interface
  5762 */
  5763 typedef struct sqlite3_vtab sqlite3_vtab;
  5764 typedef struct sqlite3_index_info sqlite3_index_info;
  5765 typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
  5766 typedef struct sqlite3_module sqlite3_module;
  5767 
  5768 /*
  5769 ** CAPI3REF: Virtual Table Object
  5770 ** KEYWORDS: sqlite3_module {virtual table module}
  5771 **
  5772 ** This structure, sometimes called a "virtual table module", 
  5773 ** defines the implementation of a [virtual tables].  
  5774 ** This structure consists mostly of methods for the module.
  5775 **
  5776 ** ^A virtual table module is created by filling in a persistent
  5777 ** instance of this structure and passing a pointer to that instance
  5778 ** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].
  5779 ** ^The registration remains valid until it is replaced by a different
  5780 ** module or until the [database connection] closes.  The content
  5781 ** of this structure must not change while it is registered with
  5782 ** any database connection.
  5783 */
  5784 struct sqlite3_module {
  5785   int iVersion;
  5786   int (*xCreate)(sqlite3*, void *pAux,
  5787                int argc, const char *const*argv,
  5788                sqlite3_vtab **ppVTab, char**);
  5789   int (*xConnect)(sqlite3*, void *pAux,
  5790                int argc, const char *const*argv,
  5791                sqlite3_vtab **ppVTab, char**);
  5792   int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
  5793   int (*xDisconnect)(sqlite3_vtab *pVTab);
  5794   int (*xDestroy)(sqlite3_vtab *pVTab);
  5795   int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
  5796   int (*xClose)(sqlite3_vtab_cursor*);
  5797   int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
  5798                 int argc, sqlite3_value **argv);
  5799   int (*xNext)(sqlite3_vtab_cursor*);
  5800   int (*xEof)(sqlite3_vtab_cursor*);
  5801   int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int);
  5802   int (*xRowid)(sqlite3_vtab_cursor*, sqlite3_int64 *pRowid);
  5803   int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite3_int64 *);
  5804   int (*xBegin)(sqlite3_vtab *pVTab);
  5805   int (*xSync)(sqlite3_vtab *pVTab);
  5806   int (*xCommit)(sqlite3_vtab *pVTab);
  5807   int (*xRollback)(sqlite3_vtab *pVTab);
  5808   int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName,
  5809                        void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
  5810                        void **ppArg);
  5811   int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
  5812   /* The methods above are in version 1 of the sqlite_module object. Those 
  5813   ** below are for version 2 and greater. */
  5814   int (*xSavepoint)(sqlite3_vtab *pVTab, int);
  5815   int (*xRelease)(sqlite3_vtab *pVTab, int);
  5816   int (*xRollbackTo)(sqlite3_vtab *pVTab, int);
  5817 };
  5818 
  5819 /*
  5820 ** CAPI3REF: Virtual Table Indexing Information
  5821 ** KEYWORDS: sqlite3_index_info
  5822 **
  5823 ** The sqlite3_index_info structure and its substructures is used as part
  5824 ** of the [virtual table] interface to
  5825 ** pass information into and receive the reply from the [xBestIndex]
  5826 ** method of a [virtual table module].  The fields under **Inputs** are the
  5827 ** inputs to xBestIndex and are read-only.  xBestIndex inserts its
  5828 ** results into the **Outputs** fields.
  5829 **
  5830 ** ^(The aConstraint[] array records WHERE clause constraints of the form:
  5831 **
  5832 ** <blockquote>column OP expr</blockquote>
  5833 **
  5834 ** where OP is =, &lt;, &lt;=, &gt;, or &gt;=.)^  ^(The particular operator is
  5835 ** stored in aConstraint[].op using one of the
  5836 ** [SQLITE_INDEX_CONSTRAINT_EQ | SQLITE_INDEX_CONSTRAINT_ values].)^
  5837 ** ^(The index of the column is stored in
  5838 ** aConstraint[].iColumn.)^  ^(aConstraint[].usable is TRUE if the
  5839 ** expr on the right-hand side can be evaluated (and thus the constraint
  5840 ** is usable) and false if it cannot.)^
  5841 **
  5842 ** ^The optimizer automatically inverts terms of the form "expr OP column"
  5843 ** and makes other simplifications to the WHERE clause in an attempt to
  5844 ** get as many WHERE clause terms into the form shown above as possible.
  5845 ** ^The aConstraint[] array only reports WHERE clause terms that are
  5846 ** relevant to the particular virtual table being queried.
  5847 **
  5848 ** ^Information about the ORDER BY clause is stored in aOrderBy[].
  5849 ** ^Each term of aOrderBy records a column of the ORDER BY clause.
  5850 **
  5851 ** The colUsed field indicates which columns of the virtual table may be
  5852 ** required by the current scan. Virtual table columns are numbered from
  5853 ** zero in the order in which they appear within the CREATE TABLE statement
  5854 ** passed to sqlite3_declare_vtab(). For the first 63 columns (columns 0-62),
  5855 ** the corresponding bit is set within the colUsed mask if the column may be
  5856 ** required by SQLite. If the table has at least 64 columns and any column
  5857 ** to the right of the first 63 is required, then bit 63 of colUsed is also
  5858 ** set. In other words, column iCol may be required if the expression
  5859 ** (colUsed & ((sqlite3_uint64)1 << (iCol>=63 ? 63 : iCol))) evaluates to 
  5860 ** non-zero.
  5861 **
  5862 ** The [xBestIndex] method must fill aConstraintUsage[] with information
  5863 ** about what parameters to pass to xFilter.  ^If argvIndex>0 then
  5864 ** the right-hand side of the corresponding aConstraint[] is evaluated
  5865 ** and becomes the argvIndex-th entry in argv.  ^(If aConstraintUsage[].omit
  5866 ** is true, then the constraint is assumed to be fully handled by the
  5867 ** virtual table and is not checked again by SQLite.)^
  5868 **
  5869 ** ^The idxNum and idxPtr values are recorded and passed into the
  5870 ** [xFilter] method.
  5871 ** ^[sqlite3_free()] is used to free idxPtr if and only if
  5872 ** needToFreeIdxPtr is true.
  5873 **
  5874 ** ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in
  5875 ** the correct order to satisfy the ORDER BY clause so that no separate
  5876 ** sorting step is required.
  5877 **
  5878 ** ^The estimatedCost value is an estimate of the cost of a particular
  5879 ** strategy. A cost of N indicates that the cost of the strategy is similar
  5880 ** to a linear scan of an SQLite table with N rows. A cost of log(N) 
  5881 ** indicates that the expense of the operation is similar to that of a
  5882 ** binary search on a unique indexed field of an SQLite table with N rows.
  5883 **
  5884 ** ^The estimatedRows value is an estimate of the number of rows that
  5885 ** will be returned by the strategy.
  5886 **
  5887 ** The xBestIndex method may optionally populate the idxFlags field with a 
  5888 ** mask of SQLITE_INDEX_SCAN_* flags. Currently there is only one such flag -
  5889 ** SQLITE_INDEX_SCAN_UNIQUE. If the xBestIndex method sets this flag, SQLite
  5890 ** assumes that the strategy may visit at most one row. 
  5891 **
  5892 ** Additionally, if xBestIndex sets the SQLITE_INDEX_SCAN_UNIQUE flag, then
  5893 ** SQLite also assumes that if a call to the xUpdate() method is made as
  5894 ** part of the same statement to delete or update a virtual table row and the
  5895 ** implementation returns SQLITE_CONSTRAINT, then there is no need to rollback
  5896 ** any database changes. In other words, if the xUpdate() returns
  5897 ** SQLITE_CONSTRAINT, the database contents must be exactly as they were
  5898 ** before xUpdate was called. By contrast, if SQLITE_INDEX_SCAN_UNIQUE is not
  5899 ** set and xUpdate returns SQLITE_CONSTRAINT, any database changes made by
  5900 ** the xUpdate method are automatically rolled back by SQLite.
  5901 **
  5902 ** IMPORTANT: The estimatedRows field was added to the sqlite3_index_info
  5903 ** structure for SQLite version 3.8.2. If a virtual table extension is
  5904 ** used with an SQLite version earlier than 3.8.2, the results of attempting 
  5905 ** to read or write the estimatedRows field are undefined (but are likely 
  5906 ** to included crashing the application). The estimatedRows field should
  5907 ** therefore only be used if [sqlite3_libversion_number()] returns a
  5908 ** value greater than or equal to 3008002. Similarly, the idxFlags field
  5909 ** was added for version 3.9.0. It may therefore only be used if
  5910 ** sqlite3_libversion_number() returns a value greater than or equal to
  5911 ** 3009000.
  5912 */
  5913 struct sqlite3_index_info {
  5914   /* Inputs */
  5915   int nConstraint;           /* Number of entries in aConstraint */
  5916   struct sqlite3_index_constraint {
  5917      int iColumn;              /* Column constrained.  -1 for ROWID */
  5918      unsigned char op;         /* Constraint operator */
  5919      unsigned char usable;     /* True if this constraint is usable */
  5920      int iTermOffset;          /* Used internally - xBestIndex should ignore */
  5921   } *aConstraint;            /* Table of WHERE clause constraints */
  5922   int nOrderBy;              /* Number of terms in the ORDER BY clause */
  5923   struct sqlite3_index_orderby {
  5924      int iColumn;              /* Column number */
  5925      unsigned char desc;       /* True for DESC.  False for ASC. */
  5926   } *aOrderBy;               /* The ORDER BY clause */
  5927   /* Outputs */
  5928   struct sqlite3_index_constraint_usage {
  5929     int argvIndex;           /* if >0, constraint is part of argv to xFilter */
  5930     unsigned char omit;      /* Do not code a test for this constraint */
  5931   } *aConstraintUsage;
  5932   int idxNum;                /* Number used to identify the index */
  5933   char *idxStr;              /* String, possibly obtained from sqlite3_malloc */
  5934   int needToFreeIdxStr;      /* Free idxStr using sqlite3_free() if true */
  5935   int orderByConsumed;       /* True if output is already ordered */
  5936   double estimatedCost;           /* Estimated cost of using this index */
  5937   /* Fields below are only available in SQLite 3.8.2 and later */
  5938   sqlite3_int64 estimatedRows;    /* Estimated number of rows returned */
  5939   /* Fields below are only available in SQLite 3.9.0 and later */
  5940   int idxFlags;              /* Mask of SQLITE_INDEX_SCAN_* flags */
  5941   /* Fields below are only available in SQLite 3.10.0 and later */
  5942   sqlite3_uint64 colUsed;    /* Input: Mask of columns used by statement */
  5943 };
  5944 
  5945 /*
  5946 ** CAPI3REF: Virtual Table Scan Flags
  5947 */
  5948 #define SQLITE_INDEX_SCAN_UNIQUE      1     /* Scan visits at most 1 row */
  5949 
  5950 /*
  5951 ** CAPI3REF: Virtual Table Constraint Operator Codes
  5952 **
  5953 ** These macros defined the allowed values for the
  5954 ** [sqlite3_index_info].aConstraint[].op field.  Each value represents
  5955 ** an operator that is part of a constraint term in the wHERE clause of
  5956 ** a query that uses a [virtual table].
  5957 */
  5958 #define SQLITE_INDEX_CONSTRAINT_EQ      2
  5959 #define SQLITE_INDEX_CONSTRAINT_GT      4
  5960 #define SQLITE_INDEX_CONSTRAINT_LE      8
  5961 #define SQLITE_INDEX_CONSTRAINT_LT     16
  5962 #define SQLITE_INDEX_CONSTRAINT_GE     32
  5963 #define SQLITE_INDEX_CONSTRAINT_MATCH  64
  5964 #define SQLITE_INDEX_CONSTRAINT_LIKE   65
  5965 #define SQLITE_INDEX_CONSTRAINT_GLOB   66
  5966 #define SQLITE_INDEX_CONSTRAINT_REGEXP 67
  5967 
  5968 /*
  5969 ** CAPI3REF: Register A Virtual Table Implementation
  5970 ** METHOD: sqlite3
  5971 **
  5972 ** ^These routines are used to register a new [virtual table module] name.
  5973 ** ^Module names must be registered before
  5974 ** creating a new [virtual table] using the module and before using a
  5975 ** preexisting [virtual table] for the module.
  5976 **
  5977 ** ^The module name is registered on the [database connection] specified
  5978 ** by the first parameter.  ^The name of the module is given by the 
  5979 ** second parameter.  ^The third parameter is a pointer to
  5980 ** the implementation of the [virtual table module].   ^The fourth
  5981 ** parameter is an arbitrary client data pointer that is passed through
  5982 ** into the [xCreate] and [xConnect] methods of the virtual table module
  5983 ** when a new virtual table is be being created or reinitialized.
  5984 **
  5985 ** ^The sqlite3_create_module_v2() interface has a fifth parameter which
  5986 ** is a pointer to a destructor for the pClientData.  ^SQLite will
  5987 ** invoke the destructor function (if it is not NULL) when SQLite
  5988 ** no longer needs the pClientData pointer.  ^The destructor will also
  5989 ** be invoked if the call to sqlite3_create_module_v2() fails.
  5990 ** ^The sqlite3_create_module()
  5991 ** interface is equivalent to sqlite3_create_module_v2() with a NULL
  5992 ** destructor.
  5993 */
  5994 SQLITE_API int SQLITE_STDCALL sqlite3_create_module(
  5995   sqlite3 *db,               /* SQLite connection to register module with */
  5996   const char *zName,         /* Name of the module */
  5997   const sqlite3_module *p,   /* Methods for the module */
  5998   void *pClientData          /* Client data for xCreate/xConnect */
  5999 );
  6000 SQLITE_API int SQLITE_STDCALL sqlite3_create_module_v2(
  6001   sqlite3 *db,               /* SQLite connection to register module with */
  6002   const char *zName,         /* Name of the module */
  6003   const sqlite3_module *p,   /* Methods for the module */
  6004   void *pClientData,         /* Client data for xCreate/xConnect */
  6005   void(*xDestroy)(void*)     /* Module destru