sqlite3.c
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1 /******************************************************************************
2 ** This file is an amalgamation of many separate C source files from SQLite
3 ** version 3.8.2. 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 #ifndef SQLITE_API
26 # define SQLITE_API
27 #endif
28 /************** Begin file sqlite3.h *****************************************/
29 /*
30 ** 2001 September 15
31 **
32 ** The author disclaims copyright to this source code. In place of
33 ** a legal notice, here is a blessing:
34 **
35 ** May you do good and not evil.
36 ** May you find forgiveness for yourself and forgive others.
37 ** May you share freely, never taking more than you give.
38 **
39 *************************************************************************
40 ** This header file defines the interface that the SQLite library
41 ** presents to client programs. If a C-function, structure, datatype,
42 ** or constant definition does not appear in this file, then it is
43 ** not a published API of SQLite, is subject to change without
44 ** notice, and should not be referenced by programs that use SQLite.
45 **
46 ** Some of the definitions that are in this file are marked as
47 ** "experimental". Experimental interfaces are normally new
48 ** features recently added to SQLite. We do not anticipate changes
49 ** to experimental interfaces but reserve the right to make minor changes
50 ** if experience from use "in the wild" suggest such changes are prudent.
51 **
52 ** The official C-language API documentation for SQLite is derived
53 ** from comments in this file. This file is the authoritative source
54 ** on how SQLite interfaces are suppose to operate.
55 **
56 ** The name of this file under configuration management is "sqlite.h.in".
57 ** The makefile makes some minor changes to this file (such as inserting
58 ** the version number) and changes its name to "sqlite3.h" as
59 ** part of the build process.
60 */
61 #ifndef _SQLITE3_H_
62 #define _SQLITE3_H_
63 #include <stdarg.h> /* Needed for the definition of va_list */
64 
65 /*
66 ** Make sure we can call this stuff from C++.
67 */
68 #if 0
69 extern "C" {
70 #endif
71 
72 
73 /*
74 ** Add the ability to override 'extern'
75 */
76 #ifndef SQLITE_EXTERN
77 # define SQLITE_EXTERN extern
78 #endif
79 
80 #ifndef SQLITE_API
81 # define SQLITE_API
82 #endif
83 
84 
85 /*
86 ** These no-op macros are used in front of interfaces to mark those
87 ** interfaces as either deprecated or experimental. New applications
88 ** should not use deprecated interfaces - they are support for backwards
89 ** compatibility only. Application writers should be aware that
90 ** experimental interfaces are subject to change in point releases.
91 **
92 ** These macros used to resolve to various kinds of compiler magic that
93 ** would generate warning messages when they were used. But that
94 ** compiler magic ended up generating such a flurry of bug reports
95 ** that we have taken it all out and gone back to using simple
96 ** noop macros.
97 */
98 #define SQLITE_DEPRECATED
99 #define SQLITE_EXPERIMENTAL
100 
101 /*
102 ** Ensure these symbols were not defined by some previous header file.
103 */
104 #ifdef SQLITE_VERSION
105 # undef SQLITE_VERSION
106 #endif
107 #ifdef SQLITE_VERSION_NUMBER
108 # undef SQLITE_VERSION_NUMBER
109 #endif
110 
111 /*
112 ** CAPI3REF: Compile-Time Library Version Numbers
113 **
114 ** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header
115 ** evaluates to a string literal that is the SQLite version in the
116 ** format "X.Y.Z" where X is the major version number (always 3 for
117 ** SQLite3) and Y is the minor version number and Z is the release number.)^
118 ** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer
119 ** with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z are the same
120 ** numbers used in [SQLITE_VERSION].)^
121 ** The SQLITE_VERSION_NUMBER for any given release of SQLite will also
122 ** be larger than the release from which it is derived. Either Y will
123 ** be held constant and Z will be incremented or else Y will be incremented
124 ** and Z will be reset to zero.
125 **
126 ** Since version 3.6.18, SQLite source code has been stored in the
127 ** <a href="http://www.fossil-scm.org/">Fossil configuration management
128 ** system</a>. ^The SQLITE_SOURCE_ID macro evaluates to
129 ** a string which identifies a particular check-in of SQLite
130 ** within its configuration management system. ^The SQLITE_SOURCE_ID
131 ** string contains the date and time of the check-in (UTC) and an SHA1
132 ** hash of the entire source tree.
133 **
134 ** See also: [sqlite3_libversion()],
135 ** [sqlite3_libversion_number()], [sqlite3_sourceid()],
136 ** [sqlite_version()] and [sqlite_source_id()].
137 */
138 #define SQLITE_VERSION "3.8.2"
139 #define SQLITE_VERSION_NUMBER 3008002
140 #define SQLITE_SOURCE_ID "2013-12-06 14:53:30 27392118af4c38c5203a04b8013e1afdb1cebd0d"
141 
142 /*
143 ** CAPI3REF: Run-Time Library Version Numbers
144 ** KEYWORDS: sqlite3_version, sqlite3_sourceid
145 **
146 ** These interfaces provide the same information as the [SQLITE_VERSION],
147 ** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
148 ** but are associated with the library instead of the header file. ^(Cautious
149 ** programmers might include assert() statements in their application to
150 ** verify that values returned by these interfaces match the macros in
151 ** the header, and thus insure that the application is
152 ** compiled with matching library and header files.
153 **
154 ** <blockquote><pre>
155 ** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
156 ** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );
157 ** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
158 ** </pre></blockquote>)^
159 **
160 ** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
161 ** macro. ^The sqlite3_libversion() function returns a pointer to the
162 ** to the sqlite3_version[] string constant. The sqlite3_libversion()
163 ** function is provided for use in DLLs since DLL users usually do not have
164 ** direct access to string constants within the DLL. ^The
165 ** sqlite3_libversion_number() function returns an integer equal to
166 ** [SQLITE_VERSION_NUMBER]. ^The sqlite3_sourceid() function returns
167 ** a pointer to a string constant whose value is the same as the
168 ** [SQLITE_SOURCE_ID] C preprocessor macro.
169 **
170 ** See also: [sqlite_version()] and [sqlite_source_id()].
171 */
173 SQLITE_API const char *sqlite3_libversion(void);
174 SQLITE_API const char *sqlite3_sourceid(void);
176 
177 /*
178 ** CAPI3REF: Run-Time Library Compilation Options Diagnostics
179 **
180 ** ^The sqlite3_compileoption_used() function returns 0 or 1
181 ** indicating whether the specified option was defined at
182 ** compile time. ^The SQLITE_ prefix may be omitted from the
183 ** option name passed to sqlite3_compileoption_used().
184 **
185 ** ^The sqlite3_compileoption_get() function allows iterating
186 ** over the list of options that were defined at compile time by
187 ** returning the N-th compile time option string. ^If N is out of range,
188 ** sqlite3_compileoption_get() returns a NULL pointer. ^The SQLITE_
189 ** prefix is omitted from any strings returned by
190 ** sqlite3_compileoption_get().
191 **
192 ** ^Support for the diagnostic functions sqlite3_compileoption_used()
193 ** and sqlite3_compileoption_get() may be omitted by specifying the
194 ** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
195 **
196 ** See also: SQL functions [sqlite_compileoption_used()] and
197 ** [sqlite_compileoption_get()] and the [compile_options pragma].
198 */
199 #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
200 SQLITE_API int sqlite3_compileoption_used(const char *zOptName);
201 SQLITE_API const char *sqlite3_compileoption_get(int N);
202 #endif
203 
204 /*
205 ** CAPI3REF: Test To See If The Library Is Threadsafe
206 **
207 ** ^The sqlite3_threadsafe() function returns zero if and only if
208 ** SQLite was compiled with mutexing code omitted due to the
209 ** [SQLITE_THREADSAFE] compile-time option being set to 0.
210 **
211 ** SQLite can be compiled with or without mutexes. When
212 ** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes
213 ** are enabled and SQLite is threadsafe. When the
214 ** [SQLITE_THREADSAFE] macro is 0,
215 ** the mutexes are omitted. Without the mutexes, it is not safe
216 ** to use SQLite concurrently from more than one thread.
217 **
218 ** Enabling mutexes incurs a measurable performance penalty.
219 ** So if speed is of utmost importance, it makes sense to disable
220 ** the mutexes. But for maximum safety, mutexes should be enabled.
221 ** ^The default behavior is for mutexes to be enabled.
222 **
223 ** This interface can be used by an application to make sure that the
224 ** version of SQLite that it is linking against was compiled with
225 ** the desired setting of the [SQLITE_THREADSAFE] macro.
226 **
227 ** This interface only reports on the compile-time mutex setting
228 ** of the [SQLITE_THREADSAFE] flag. If SQLite is compiled with
229 ** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but
230 ** can be fully or partially disabled using a call to [sqlite3_config()]
231 ** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],
232 ** or [SQLITE_CONFIG_MUTEX]. ^(The return value of the
233 ** sqlite3_threadsafe() function shows only the compile-time setting of
234 ** thread safety, not any run-time changes to that setting made by
235 ** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()
236 ** is unchanged by calls to sqlite3_config().)^
237 **
238 ** See the [threading mode] documentation for additional information.
239 */
241 
242 /*
243 ** CAPI3REF: Database Connection Handle
244 ** KEYWORDS: {database connection} {database connections}
245 **
246 ** Each open SQLite database is represented by a pointer to an instance of
247 ** the opaque structure named "sqlite3". It is useful to think of an sqlite3
248 ** pointer as an object. The [sqlite3_open()], [sqlite3_open16()], and
249 ** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
250 ** and [sqlite3_close_v2()] are its destructors. There are many other
251 ** interfaces (such as
252 ** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
253 ** [sqlite3_busy_timeout()] to name but three) that are methods on an
254 ** sqlite3 object.
255 */
256 typedef struct sqlite3 sqlite3;
257 
258 /*
259 ** CAPI3REF: 64-Bit Integer Types
260 ** KEYWORDS: sqlite_int64 sqlite_uint64
261 **
262 ** Because there is no cross-platform way to specify 64-bit integer types
263 ** SQLite includes typedefs for 64-bit signed and unsigned integers.
264 **
265 ** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
266 ** The sqlite_int64 and sqlite_uint64 types are supported for backwards
267 ** compatibility only.
268 **
269 ** ^The sqlite3_int64 and sqlite_int64 types can store integer values
270 ** between -9223372036854775808 and +9223372036854775807 inclusive. ^The
271 ** sqlite3_uint64 and sqlite_uint64 types can store integer values
272 ** between 0 and +18446744073709551615 inclusive.
273 */
274 #ifdef SQLITE_INT64_TYPE
275  typedef SQLITE_INT64_TYPE sqlite_int64;
276  typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
277 #elif defined(_MSC_VER) || defined(__BORLANDC__)
278  typedef __int64 sqlite_int64;
279  typedef unsigned __int64 sqlite_uint64;
280 #else
281  typedef long long int sqlite_int64;
282  typedef unsigned long long int sqlite_uint64;
283 #endif
284 typedef sqlite_int64 sqlite3_int64;
285 typedef sqlite_uint64 sqlite3_uint64;
286 
287 /*
288 ** If compiling for a processor that lacks floating point support,
289 ** substitute integer for floating-point.
290 */
291 #ifdef SQLITE_OMIT_FLOATING_POINT
292 # define double sqlite3_int64
293 #endif
294 
295 /*
296 ** CAPI3REF: Closing A Database Connection
297 **
298 ** ^The sqlite3_close() and sqlite3_close_v2() routines are destructors
299 ** for the [sqlite3] object.
300 ** ^Calls to sqlite3_close() and sqlite3_close_v2() return SQLITE_OK if
301 ** the [sqlite3] object is successfully destroyed and all associated
302 ** resources are deallocated.
303 **
304 ** ^If the database connection is associated with unfinalized prepared
305 ** statements or unfinished sqlite3_backup objects then sqlite3_close()
306 ** will leave the database connection open and return [SQLITE_BUSY].
307 ** ^If sqlite3_close_v2() is called with unfinalized prepared statements
308 ** and unfinished sqlite3_backups, then the database connection becomes
309 ** an unusable "zombie" which will automatically be deallocated when the
310 ** last prepared statement is finalized or the last sqlite3_backup is
311 ** finished. The sqlite3_close_v2() interface is intended for use with
312 ** host languages that are garbage collected, and where the order in which
313 ** destructors are called is arbitrary.
314 **
315 ** Applications should [sqlite3_finalize | finalize] all [prepared statements],
316 ** [sqlite3_blob_close | close] all [BLOB handles], and
317 ** [sqlite3_backup_finish | finish] all [sqlite3_backup] objects associated
318 ** with the [sqlite3] object prior to attempting to close the object. ^If
319 ** sqlite3_close_v2() is called on a [database connection] that still has
320 ** outstanding [prepared statements], [BLOB handles], and/or
321 ** [sqlite3_backup] objects then it returns SQLITE_OK but the deallocation
322 ** of resources is deferred until all [prepared statements], [BLOB handles],
323 ** and [sqlite3_backup] objects are also destroyed.
324 **
325 ** ^If an [sqlite3] object is destroyed while a transaction is open,
326 ** the transaction is automatically rolled back.
327 **
328 ** The C parameter to [sqlite3_close(C)] and [sqlite3_close_v2(C)]
329 ** must be either a NULL
330 ** pointer or an [sqlite3] object pointer obtained
331 ** from [sqlite3_open()], [sqlite3_open16()], or
332 ** [sqlite3_open_v2()], and not previously closed.
333 ** ^Calling sqlite3_close() or sqlite3_close_v2() with a NULL pointer
334 ** argument is a harmless no-op.
335 */
338 
339 /*
340 ** The type for a callback function.
341 ** This is legacy and deprecated. It is included for historical
342 ** compatibility and is not documented.
343 */
344 typedef int (*sqlite3_callback)(void*,int,char**, char**);
345 
346 /*
347 ** CAPI3REF: One-Step Query Execution Interface
348 **
349 ** The sqlite3_exec() interface is a convenience wrapper around
350 ** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],
351 ** that allows an application to run multiple statements of SQL
352 ** without having to use a lot of C code.
353 **
354 ** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
355 ** semicolon-separate SQL statements passed into its 2nd argument,
356 ** in the context of the [database connection] passed in as its 1st
357 ** argument. ^If the callback function of the 3rd argument to
358 ** sqlite3_exec() is not NULL, then it is invoked for each result row
359 ** coming out of the evaluated SQL statements. ^The 4th argument to
360 ** sqlite3_exec() is relayed through to the 1st argument of each
361 ** callback invocation. ^If the callback pointer to sqlite3_exec()
362 ** is NULL, then no callback is ever invoked and result rows are
363 ** ignored.
364 **
365 ** ^If an error occurs while evaluating the SQL statements passed into
366 ** sqlite3_exec(), then execution of the current statement stops and
367 ** subsequent statements are skipped. ^If the 5th parameter to sqlite3_exec()
368 ** is not NULL then any error message is written into memory obtained
369 ** from [sqlite3_malloc()] and passed back through the 5th parameter.
370 ** To avoid memory leaks, the application should invoke [sqlite3_free()]
371 ** on error message strings returned through the 5th parameter of
372 ** of sqlite3_exec() after the error message string is no longer needed.
373 ** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
374 ** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
375 ** NULL before returning.
376 **
377 ** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()
378 ** routine returns SQLITE_ABORT without invoking the callback again and
379 ** without running any subsequent SQL statements.
380 **
381 ** ^The 2nd argument to the sqlite3_exec() callback function is the
382 ** number of columns in the result. ^The 3rd argument to the sqlite3_exec()
383 ** callback is an array of pointers to strings obtained as if from
384 ** [sqlite3_column_text()], one for each column. ^If an element of a
385 ** result row is NULL then the corresponding string pointer for the
386 ** sqlite3_exec() callback is a NULL pointer. ^The 4th argument to the
387 ** sqlite3_exec() callback is an array of pointers to strings where each
388 ** entry represents the name of corresponding result column as obtained
389 ** from [sqlite3_column_name()].
390 **
391 ** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer
392 ** to an empty string, or a pointer that contains only whitespace and/or
393 ** SQL comments, then no SQL statements are evaluated and the database
394 ** is not changed.
395 **
396 ** Restrictions:
397 **
398 ** <ul>
399 ** <li> The application must insure that the 1st parameter to sqlite3_exec()
400 ** is a valid and open [database connection].
401 ** <li> The application must not close the [database connection] specified by
402 ** the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
403 ** <li> The application must not modify the SQL statement text passed into
404 ** the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.
405 ** </ul>
406 */
408  sqlite3*, /* An open database */
409  const char *sql, /* SQL to be evaluated */
410  int (*callback)(void*,int,char**,char**), /* Callback function */
411  void *, /* 1st argument to callback */
412  char **errmsg /* Error msg written here */
413 );
414 
415 /*
416 ** CAPI3REF: Result Codes
417 ** KEYWORDS: SQLITE_OK {error code} {error codes}
418 ** KEYWORDS: {result code} {result codes}
419 **
420 ** Many SQLite functions return an integer result code from the set shown
421 ** here in order to indicate success or failure.
422 **
423 ** New error codes may be added in future versions of SQLite.
424 **
425 ** See also: [SQLITE_IOERR_READ | extended result codes],
426 ** [sqlite3_vtab_on_conflict()] [SQLITE_ROLLBACK | result codes].
427 */
428 #define SQLITE_OK 0 /* Successful result */
429 /* beginning-of-error-codes */
430 #define SQLITE_ERROR 1 /* SQL error or missing database */
431 #define SQLITE_INTERNAL 2 /* Internal logic error in SQLite */
432 #define SQLITE_PERM 3 /* Access permission denied */
433 #define SQLITE_ABORT 4 /* Callback routine requested an abort */
434 #define SQLITE_BUSY 5 /* The database file is locked */
435 #define SQLITE_LOCKED 6 /* A table in the database is locked */
436 #define SQLITE_NOMEM 7 /* A malloc() failed */
437 #define SQLITE_READONLY 8 /* Attempt to write a readonly database */
438 #define SQLITE_INTERRUPT 9 /* Operation terminated by sqlite3_interrupt()*/
439 #define SQLITE_IOERR 10 /* Some kind of disk I/O error occurred */
440 #define SQLITE_CORRUPT 11 /* The database disk image is malformed */
441 #define SQLITE_NOTFOUND 12 /* Unknown opcode in sqlite3_file_control() */
442 #define SQLITE_FULL 13 /* Insertion failed because database is full */
443 #define SQLITE_CANTOPEN 14 /* Unable to open the database file */
444 #define SQLITE_PROTOCOL 15 /* Database lock protocol error */
445 #define SQLITE_EMPTY 16 /* Database is empty */
446 #define SQLITE_SCHEMA 17 /* The database schema changed */
447 #define SQLITE_TOOBIG 18 /* String or BLOB exceeds size limit */
448 #define SQLITE_CONSTRAINT 19 /* Abort due to constraint violation */
449 #define SQLITE_MISMATCH 20 /* Data type mismatch */
450 #define SQLITE_MISUSE 21 /* Library used incorrectly */
451 #define SQLITE_NOLFS 22 /* Uses OS features not supported on host */
452 #define SQLITE_AUTH 23 /* Authorization denied */
453 #define SQLITE_FORMAT 24 /* Auxiliary database format error */
454 #define SQLITE_RANGE 25 /* 2nd parameter to sqlite3_bind out of range */
455 #define SQLITE_NOTADB 26 /* File opened that is not a database file */
456 #define SQLITE_NOTICE 27 /* Notifications from sqlite3_log() */
457 #define SQLITE_WARNING 28 /* Warnings from sqlite3_log() */
458 #define SQLITE_ROW 100 /* sqlite3_step() has another row ready */
459 #define SQLITE_DONE 101 /* sqlite3_step() has finished executing */
460 /* end-of-error-codes */
461 
462 /*
463 ** CAPI3REF: Extended Result Codes
464 ** KEYWORDS: {extended error code} {extended error codes}
465 ** KEYWORDS: {extended result code} {extended result codes}
466 **
467 ** In its default configuration, SQLite API routines return one of 26 integer
468 ** [SQLITE_OK | result codes]. However, experience has shown that many of
469 ** these result codes are too coarse-grained. They do not provide as
470 ** much information about problems as programmers might like. In an effort to
471 ** address this, newer versions of SQLite (version 3.3.8 and later) include
472 ** support for additional result codes that provide more detailed information
473 ** about errors. The extended result codes are enabled or disabled
474 ** on a per database connection basis using the
475 ** [sqlite3_extended_result_codes()] API.
476 **
477 ** Some of the available extended result codes are listed here.
478 ** One may expect the number of extended result codes will increase
479 ** over time. Software that uses extended result codes should expect
480 ** to see new result codes in future releases of SQLite.
481 **
482 ** The SQLITE_OK result code will never be extended. It will always
483 ** be exactly zero.
484 */
485 #define SQLITE_IOERR_READ (SQLITE_IOERR | (1<<8))
486 #define SQLITE_IOERR_SHORT_READ (SQLITE_IOERR | (2<<8))
487 #define SQLITE_IOERR_WRITE (SQLITE_IOERR | (3<<8))
488 #define SQLITE_IOERR_FSYNC (SQLITE_IOERR | (4<<8))
489 #define SQLITE_IOERR_DIR_FSYNC (SQLITE_IOERR | (5<<8))
490 #define SQLITE_IOERR_TRUNCATE (SQLITE_IOERR | (6<<8))
491 #define SQLITE_IOERR_FSTAT (SQLITE_IOERR | (7<<8))
492 #define SQLITE_IOERR_UNLOCK (SQLITE_IOERR | (8<<8))
493 #define SQLITE_IOERR_RDLOCK (SQLITE_IOERR | (9<<8))
494 #define SQLITE_IOERR_DELETE (SQLITE_IOERR | (10<<8))
495 #define SQLITE_IOERR_BLOCKED (SQLITE_IOERR | (11<<8))
496 #define SQLITE_IOERR_NOMEM (SQLITE_IOERR | (12<<8))
497 #define SQLITE_IOERR_ACCESS (SQLITE_IOERR | (13<<8))
498 #define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
499 #define SQLITE_IOERR_LOCK (SQLITE_IOERR | (15<<8))
500 #define SQLITE_IOERR_CLOSE (SQLITE_IOERR | (16<<8))
501 #define SQLITE_IOERR_DIR_CLOSE (SQLITE_IOERR | (17<<8))
502 #define SQLITE_IOERR_SHMOPEN (SQLITE_IOERR | (18<<8))
503 #define SQLITE_IOERR_SHMSIZE (SQLITE_IOERR | (19<<8))
504 #define SQLITE_IOERR_SHMLOCK (SQLITE_IOERR | (20<<8))
505 #define SQLITE_IOERR_SHMMAP (SQLITE_IOERR | (21<<8))
506 #define SQLITE_IOERR_SEEK (SQLITE_IOERR | (22<<8))
507 #define SQLITE_IOERR_DELETE_NOENT (SQLITE_IOERR | (23<<8))
508 #define SQLITE_IOERR_MMAP (SQLITE_IOERR | (24<<8))
509 #define SQLITE_IOERR_GETTEMPPATH (SQLITE_IOERR | (25<<8))
510 #define SQLITE_IOERR_CONVPATH (SQLITE_IOERR | (26<<8))
511 #define SQLITE_LOCKED_SHAREDCACHE (SQLITE_LOCKED | (1<<8))
512 #define SQLITE_BUSY_RECOVERY (SQLITE_BUSY | (1<<8))
513 #define SQLITE_BUSY_SNAPSHOT (SQLITE_BUSY | (2<<8))
514 #define SQLITE_CANTOPEN_NOTEMPDIR (SQLITE_CANTOPEN | (1<<8))
515 #define SQLITE_CANTOPEN_ISDIR (SQLITE_CANTOPEN | (2<<8))
516 #define SQLITE_CANTOPEN_FULLPATH (SQLITE_CANTOPEN | (3<<8))
517 #define SQLITE_CANTOPEN_CONVPATH (SQLITE_CANTOPEN | (4<<8))
518 #define SQLITE_CORRUPT_VTAB (SQLITE_CORRUPT | (1<<8))
519 #define SQLITE_READONLY_RECOVERY (SQLITE_READONLY | (1<<8))
520 #define SQLITE_READONLY_CANTLOCK (SQLITE_READONLY | (2<<8))
521 #define SQLITE_READONLY_ROLLBACK (SQLITE_READONLY | (3<<8))
522 #define SQLITE_ABORT_ROLLBACK (SQLITE_ABORT | (2<<8))
523 #define SQLITE_CONSTRAINT_CHECK (SQLITE_CONSTRAINT | (1<<8))
524 #define SQLITE_CONSTRAINT_COMMITHOOK (SQLITE_CONSTRAINT | (2<<8))
525 #define SQLITE_CONSTRAINT_FOREIGNKEY (SQLITE_CONSTRAINT | (3<<8))
526 #define SQLITE_CONSTRAINT_FUNCTION (SQLITE_CONSTRAINT | (4<<8))
527 #define SQLITE_CONSTRAINT_NOTNULL (SQLITE_CONSTRAINT | (5<<8))
528 #define SQLITE_CONSTRAINT_PRIMARYKEY (SQLITE_CONSTRAINT | (6<<8))
529 #define SQLITE_CONSTRAINT_TRIGGER (SQLITE_CONSTRAINT | (7<<8))
530 #define SQLITE_CONSTRAINT_UNIQUE (SQLITE_CONSTRAINT | (8<<8))
531 #define SQLITE_CONSTRAINT_VTAB (SQLITE_CONSTRAINT | (9<<8))
532 #define SQLITE_CONSTRAINT_ROWID (SQLITE_CONSTRAINT |(10<<8))
533 #define SQLITE_NOTICE_RECOVER_WAL (SQLITE_NOTICE | (1<<8))
534 #define SQLITE_NOTICE_RECOVER_ROLLBACK (SQLITE_NOTICE | (2<<8))
535 #define SQLITE_WARNING_AUTOINDEX (SQLITE_WARNING | (1<<8))
536 
537 /*
538 ** CAPI3REF: Flags For File Open Operations
539 **
540 ** These bit values are intended for use in the
541 ** 3rd parameter to the [sqlite3_open_v2()] interface and
542 ** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
543 */
544 #define SQLITE_OPEN_READONLY 0x00000001 /* Ok for sqlite3_open_v2() */
545 #define SQLITE_OPEN_READWRITE 0x00000002 /* Ok for sqlite3_open_v2() */
546 #define SQLITE_OPEN_CREATE 0x00000004 /* Ok for sqlite3_open_v2() */
547 #define SQLITE_OPEN_DELETEONCLOSE 0x00000008 /* VFS only */
548 #define SQLITE_OPEN_EXCLUSIVE 0x00000010 /* VFS only */
549 #define SQLITE_OPEN_AUTOPROXY 0x00000020 /* VFS only */
550 #define SQLITE_OPEN_URI 0x00000040 /* Ok for sqlite3_open_v2() */
551 #define SQLITE_OPEN_MEMORY 0x00000080 /* Ok for sqlite3_open_v2() */
552 #define SQLITE_OPEN_MAIN_DB 0x00000100 /* VFS only */
553 #define SQLITE_OPEN_TEMP_DB 0x00000200 /* VFS only */
554 #define SQLITE_OPEN_TRANSIENT_DB 0x00000400 /* VFS only */
555 #define SQLITE_OPEN_MAIN_JOURNAL 0x00000800 /* VFS only */
556 #define SQLITE_OPEN_TEMP_JOURNAL 0x00001000 /* VFS only */
557 #define SQLITE_OPEN_SUBJOURNAL 0x00002000 /* VFS only */
558 #define SQLITE_OPEN_MASTER_JOURNAL 0x00004000 /* VFS only */
559 #define SQLITE_OPEN_NOMUTEX 0x00008000 /* Ok for sqlite3_open_v2() */
560 #define SQLITE_OPEN_FULLMUTEX 0x00010000 /* Ok for sqlite3_open_v2() */
561 #define SQLITE_OPEN_SHAREDCACHE 0x00020000 /* Ok for sqlite3_open_v2() */
562 #define SQLITE_OPEN_PRIVATECACHE 0x00040000 /* Ok for sqlite3_open_v2() */
563 #define SQLITE_OPEN_WAL 0x00080000 /* VFS only */
564 
565 /* Reserved: 0x00F00000 */
566 
567 /*
568 ** CAPI3REF: Device Characteristics
569 **
570 ** The xDeviceCharacteristics method of the [sqlite3_io_methods]
571 ** object returns an integer which is a vector of these
572 ** bit values expressing I/O characteristics of the mass storage
573 ** device that holds the file that the [sqlite3_io_methods]
574 ** refers to.
575 **
576 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
577 ** any size are atomic. The SQLITE_IOCAP_ATOMICnnn values
578 ** mean that writes of blocks that are nnn bytes in size and
579 ** are aligned to an address which is an integer multiple of
580 ** nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means
581 ** that when data is appended to a file, the data is appended
582 ** first then the size of the file is extended, never the other
583 ** way around. The SQLITE_IOCAP_SEQUENTIAL property means that
584 ** information is written to disk in the same order as calls
585 ** to xWrite(). The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that
586 ** after reboot following a crash or power loss, the only bytes in a
587 ** file that were written at the application level might have changed
588 ** and that adjacent bytes, even bytes within the same sector are
589 ** guaranteed to be unchanged.
590 */
591 #define SQLITE_IOCAP_ATOMIC 0x00000001
592 #define SQLITE_IOCAP_ATOMIC512 0x00000002
593 #define SQLITE_IOCAP_ATOMIC1K 0x00000004
594 #define SQLITE_IOCAP_ATOMIC2K 0x00000008
595 #define SQLITE_IOCAP_ATOMIC4K 0x00000010
596 #define SQLITE_IOCAP_ATOMIC8K 0x00000020
597 #define SQLITE_IOCAP_ATOMIC16K 0x00000040
598 #define SQLITE_IOCAP_ATOMIC32K 0x00000080
599 #define SQLITE_IOCAP_ATOMIC64K 0x00000100
600 #define SQLITE_IOCAP_SAFE_APPEND 0x00000200
601 #define SQLITE_IOCAP_SEQUENTIAL 0x00000400
602 #define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN 0x00000800
603 #define SQLITE_IOCAP_POWERSAFE_OVERWRITE 0x00001000
604 
605 /*
606 ** CAPI3REF: File Locking Levels
607 **
608 ** SQLite uses one of these integer values as the second
609 ** argument to calls it makes to the xLock() and xUnlock() methods
610 ** of an [sqlite3_io_methods] object.
611 */
612 #define SQLITE_LOCK_NONE 0
613 #define SQLITE_LOCK_SHARED 1
614 #define SQLITE_LOCK_RESERVED 2
615 #define SQLITE_LOCK_PENDING 3
616 #define SQLITE_LOCK_EXCLUSIVE 4
617 
618 /*
619 ** CAPI3REF: Synchronization Type Flags
620 **
621 ** When SQLite invokes the xSync() method of an
622 ** [sqlite3_io_methods] object it uses a combination of
623 ** these integer values as the second argument.
624 **
625 ** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
626 ** sync operation only needs to flush data to mass storage. Inode
627 ** information need not be flushed. If the lower four bits of the flag
628 ** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.
629 ** If the lower four bits equal SQLITE_SYNC_FULL, that means
630 ** to use Mac OS X style fullsync instead of fsync().
631 **
632 ** Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags
633 ** with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL
634 ** settings. The [synchronous pragma] determines when calls to the
635 ** xSync VFS method occur and applies uniformly across all platforms.
636 ** The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how
637 ** energetic or rigorous or forceful the sync operations are and
638 ** only make a difference on Mac OSX for the default SQLite code.
639 ** (Third-party VFS implementations might also make the distinction
640 ** between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the
641 ** operating systems natively supported by SQLite, only Mac OSX
642 ** cares about the difference.)
643 */
644 #define SQLITE_SYNC_NORMAL 0x00002
645 #define SQLITE_SYNC_FULL 0x00003
646 #define SQLITE_SYNC_DATAONLY 0x00010
647 
648 /*
649 ** CAPI3REF: OS Interface Open File Handle
650 **
651 ** An [sqlite3_file] object represents an open file in the
652 ** [sqlite3_vfs | OS interface layer]. Individual OS interface
653 ** implementations will
654 ** want to subclass this object by appending additional fields
655 ** for their own use. The pMethods entry is a pointer to an
656 ** [sqlite3_io_methods] object that defines methods for performing
657 ** I/O operations on the open file.
658 */
659 typedef struct sqlite3_file sqlite3_file;
660 struct sqlite3_file {
661  const struct sqlite3_io_methods *pMethods; /* Methods for an open file */
662 };
663 
664 /*
665 ** CAPI3REF: OS Interface File Virtual Methods Object
666 **
667 ** Every file opened by the [sqlite3_vfs.xOpen] method populates an
668 ** [sqlite3_file] object (or, more commonly, a subclass of the
669 ** [sqlite3_file] object) with a pointer to an instance of this object.
670 ** This object defines the methods used to perform various operations
671 ** against the open file represented by the [sqlite3_file] object.
672 **
673 ** If the [sqlite3_vfs.xOpen] method sets the sqlite3_file.pMethods element
674 ** to a non-NULL pointer, then the sqlite3_io_methods.xClose method
675 ** may be invoked even if the [sqlite3_vfs.xOpen] reported that it failed. The
676 ** only way to prevent a call to xClose following a failed [sqlite3_vfs.xOpen]
677 ** is for the [sqlite3_vfs.xOpen] to set the sqlite3_file.pMethods element
678 ** to NULL.
679 **
680 ** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
681 ** [SQLITE_SYNC_FULL]. The first choice is the normal fsync().
682 ** The second choice is a Mac OS X style fullsync. The [SQLITE_SYNC_DATAONLY]
683 ** flag may be ORed in to indicate that only the data of the file
684 ** and not its inode needs to be synced.
685 **
686 ** The integer values to xLock() and xUnlock() are one of
687 ** <ul>
688 ** <li> [SQLITE_LOCK_NONE],
689 ** <li> [SQLITE_LOCK_SHARED],
690 ** <li> [SQLITE_LOCK_RESERVED],
691 ** <li> [SQLITE_LOCK_PENDING], or
692 ** <li> [SQLITE_LOCK_EXCLUSIVE].
693 ** </ul>
694 ** xLock() increases the lock. xUnlock() decreases the lock.
695 ** The xCheckReservedLock() method checks whether any database connection,
696 ** either in this process or in some other process, is holding a RESERVED,
697 ** PENDING, or EXCLUSIVE lock on the file. It returns true
698 ** if such a lock exists and false otherwise.
699 **
700 ** The xFileControl() method is a generic interface that allows custom
701 ** VFS implementations to directly control an open file using the
702 ** [sqlite3_file_control()] interface. The second "op" argument is an
703 ** integer opcode. The third argument is a generic pointer intended to
704 ** point to a structure that may contain arguments or space in which to
705 ** write return values. Potential uses for xFileControl() might be
706 ** functions to enable blocking locks with timeouts, to change the
707 ** locking strategy (for example to use dot-file locks), to inquire
708 ** about the status of a lock, or to break stale locks. The SQLite
709 ** core reserves all opcodes less than 100 for its own use.
710 ** A [SQLITE_FCNTL_LOCKSTATE | list of opcodes] less than 100 is available.
711 ** Applications that define a custom xFileControl method should use opcodes
712 ** greater than 100 to avoid conflicts. VFS implementations should
713 ** return [SQLITE_NOTFOUND] for file control opcodes that they do not
714 ** recognize.
715 **
716 ** The xSectorSize() method returns the sector size of the
717 ** device that underlies the file. The sector size is the
718 ** minimum write that can be performed without disturbing
719 ** other bytes in the file. The xDeviceCharacteristics()
720 ** method returns a bit vector describing behaviors of the
721 ** underlying device:
722 **
723 ** <ul>
724 ** <li> [SQLITE_IOCAP_ATOMIC]
725 ** <li> [SQLITE_IOCAP_ATOMIC512]
726 ** <li> [SQLITE_IOCAP_ATOMIC1K]
727 ** <li> [SQLITE_IOCAP_ATOMIC2K]
728 ** <li> [SQLITE_IOCAP_ATOMIC4K]
729 ** <li> [SQLITE_IOCAP_ATOMIC8K]
730 ** <li> [SQLITE_IOCAP_ATOMIC16K]
731 ** <li> [SQLITE_IOCAP_ATOMIC32K]
732 ** <li> [SQLITE_IOCAP_ATOMIC64K]
733 ** <li> [SQLITE_IOCAP_SAFE_APPEND]
734 ** <li> [SQLITE_IOCAP_SEQUENTIAL]
735 ** </ul>
736 **
737 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
738 ** any size are atomic. The SQLITE_IOCAP_ATOMICnnn values
739 ** mean that writes of blocks that are nnn bytes in size and
740 ** are aligned to an address which is an integer multiple of
741 ** nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means
742 ** that when data is appended to a file, the data is appended
743 ** first then the size of the file is extended, never the other
744 ** way around. The SQLITE_IOCAP_SEQUENTIAL property means that
745 ** information is written to disk in the same order as calls
746 ** to xWrite().
747 **
748 ** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
749 ** in the unread portions of the buffer with zeros. A VFS that
750 ** fails to zero-fill short reads might seem to work. However,
751 ** failure to zero-fill short reads will eventually lead to
752 ** database corruption.
753 */
756  int iVersion;
757  int (*xClose)(sqlite3_file*);
758  int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
759  int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
760  int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
761  int (*xSync)(sqlite3_file*, int flags);
762  int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
763  int (*xLock)(sqlite3_file*, int);
764  int (*xUnlock)(sqlite3_file*, int);
765  int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
766  int (*xFileControl)(sqlite3_file*, int op, void *pArg);
767  int (*xSectorSize)(sqlite3_file*);
768  int (*xDeviceCharacteristics)(sqlite3_file*);
769  /* Methods above are valid for version 1 */
770  int (*xShmMap)(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
771  int (*xShmLock)(sqlite3_file*, int offset, int n, int flags);
772  void (*xShmBarrier)(sqlite3_file*);
773  int (*xShmUnmap)(sqlite3_file*, int deleteFlag);
774  /* Methods above are valid for version 2 */
775  int (*xFetch)(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
776  int (*xUnfetch)(sqlite3_file*, sqlite3_int64 iOfst, void *p);
777  /* Methods above are valid for version 3 */
778  /* Additional methods may be added in future releases */
779 };
780 
781 /*
782 ** CAPI3REF: Standard File Control Opcodes
783 **
784 ** These integer constants are opcodes for the xFileControl method
785 ** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
786 ** interface.
787 **
788 ** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging. This
789 ** opcode causes the xFileControl method to write the current state of
790 ** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
791 ** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
792 ** into an integer that the pArg argument points to. This capability
793 ** is used during testing and only needs to be supported when SQLITE_TEST
794 ** is defined.
795 ** <ul>
796 ** <li>[[SQLITE_FCNTL_SIZE_HINT]]
797 ** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
798 ** layer a hint of how large the database file will grow to be during the
799 ** current transaction. This hint is not guaranteed to be accurate but it
800 ** is often close. The underlying VFS might choose to preallocate database
801 ** file space based on this hint in order to help writes to the database
802 ** file run faster.
803 **
804 ** <li>[[SQLITE_FCNTL_CHUNK_SIZE]]
805 ** The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS
806 ** extends and truncates the database file in chunks of a size specified
807 ** by the user. The fourth argument to [sqlite3_file_control()] should
808 ** point to an integer (type int) containing the new chunk-size to use
809 ** for the nominated database. Allocating database file space in large
810 ** chunks (say 1MB at a time), may reduce file-system fragmentation and
811 ** improve performance on some systems.
812 **
813 ** <li>[[SQLITE_FCNTL_FILE_POINTER]]
814 ** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
815 ** to the [sqlite3_file] object associated with a particular database
816 ** connection. See the [sqlite3_file_control()] documentation for
817 ** additional information.
818 **
819 ** <li>[[SQLITE_FCNTL_SYNC_OMITTED]]
820 ** ^(The [SQLITE_FCNTL_SYNC_OMITTED] opcode is generated internally by
821 ** SQLite and sent to all VFSes in place of a call to the xSync method
822 ** when the database connection has [PRAGMA synchronous] set to OFF.)^
823 ** Some specialized VFSes need this signal in order to operate correctly
824 ** when [PRAGMA synchronous | PRAGMA synchronous=OFF] is set, but most
825 ** VFSes do not need this signal and should silently ignore this opcode.
826 ** Applications should not call [sqlite3_file_control()] with this
827 ** opcode as doing so may disrupt the operation of the specialized VFSes
828 ** that do require it.
829 **
830 ** <li>[[SQLITE_FCNTL_WIN32_AV_RETRY]]
831 ** ^The [SQLITE_FCNTL_WIN32_AV_RETRY] opcode is used to configure automatic
832 ** retry counts and intervals for certain disk I/O operations for the
833 ** windows [VFS] in order to provide robustness in the presence of
834 ** anti-virus programs. By default, the windows VFS will retry file read,
835 ** file write, and file delete operations up to 10 times, with a delay
836 ** of 25 milliseconds before the first retry and with the delay increasing
837 ** by an additional 25 milliseconds with each subsequent retry. This
838 ** opcode allows these two values (10 retries and 25 milliseconds of delay)
839 ** to be adjusted. The values are changed for all database connections
840 ** within the same process. The argument is a pointer to an array of two
841 ** integers where the first integer i the new retry count and the second
842 ** integer is the delay. If either integer is negative, then the setting
843 ** is not changed but instead the prior value of that setting is written
844 ** into the array entry, allowing the current retry settings to be
845 ** interrogated. The zDbName parameter is ignored.
846 **
847 ** <li>[[SQLITE_FCNTL_PERSIST_WAL]]
848 ** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the
849 ** persistent [WAL | Write Ahead Log] setting. By default, the auxiliary
850 ** write ahead log and shared memory files used for transaction control
851 ** are automatically deleted when the latest connection to the database
852 ** closes. Setting persistent WAL mode causes those files to persist after
853 ** close. Persisting the files is useful when other processes that do not
854 ** have write permission on the directory containing the database file want
855 ** to read the database file, as the WAL and shared memory files must exist
856 ** in order for the database to be readable. The fourth parameter to
857 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
858 ** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
859 ** WAL mode. If the integer is -1, then it is overwritten with the current
860 ** WAL persistence setting.
861 **
862 ** <li>[[SQLITE_FCNTL_POWERSAFE_OVERWRITE]]
863 ** ^The [SQLITE_FCNTL_POWERSAFE_OVERWRITE] opcode is used to set or query the
864 ** persistent "powersafe-overwrite" or "PSOW" setting. The PSOW setting
865 ** determines the [SQLITE_IOCAP_POWERSAFE_OVERWRITE] bit of the
866 ** xDeviceCharacteristics methods. The fourth parameter to
867 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
868 ** That integer is 0 to disable zero-damage mode or 1 to enable zero-damage
869 ** mode. If the integer is -1, then it is overwritten with the current
870 ** zero-damage mode setting.
871 **
872 ** <li>[[SQLITE_FCNTL_OVERWRITE]]
873 ** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
874 ** a write transaction to indicate that, unless it is rolled back for some
875 ** reason, the entire database file will be overwritten by the current
876 ** transaction. This is used by VACUUM operations.
877 **
878 ** <li>[[SQLITE_FCNTL_VFSNAME]]
879 ** ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of
880 ** all [VFSes] in the VFS stack. The names are of all VFS shims and the
881 ** final bottom-level VFS are written into memory obtained from
882 ** [sqlite3_malloc()] and the result is stored in the char* variable
883 ** that the fourth parameter of [sqlite3_file_control()] points to.
884 ** The caller is responsible for freeing the memory when done. As with
885 ** all file-control actions, there is no guarantee that this will actually
886 ** do anything. Callers should initialize the char* variable to a NULL
887 ** pointer in case this file-control is not implemented. This file-control
888 ** is intended for diagnostic use only.
889 **
890 ** <li>[[SQLITE_FCNTL_PRAGMA]]
891 ** ^Whenever a [PRAGMA] statement is parsed, an [SQLITE_FCNTL_PRAGMA]
892 ** file control is sent to the open [sqlite3_file] object corresponding
893 ** to the database file to which the pragma statement refers. ^The argument
894 ** to the [SQLITE_FCNTL_PRAGMA] file control is an array of
895 ** pointers to strings (char**) in which the second element of the array
896 ** is the name of the pragma and the third element is the argument to the
897 ** pragma or NULL if the pragma has no argument. ^The handler for an
898 ** [SQLITE_FCNTL_PRAGMA] file control can optionally make the first element
899 ** of the char** argument point to a string obtained from [sqlite3_mprintf()]
900 ** or the equivalent and that string will become the result of the pragma or
901 ** the error message if the pragma fails. ^If the
902 ** [SQLITE_FCNTL_PRAGMA] file control returns [SQLITE_NOTFOUND], then normal
903 ** [PRAGMA] processing continues. ^If the [SQLITE_FCNTL_PRAGMA]
904 ** file control returns [SQLITE_OK], then the parser assumes that the
905 ** VFS has handled the PRAGMA itself and the parser generates a no-op
906 ** prepared statement. ^If the [SQLITE_FCNTL_PRAGMA] file control returns
907 ** any result code other than [SQLITE_OK] or [SQLITE_NOTFOUND], that means
908 ** that the VFS encountered an error while handling the [PRAGMA] and the
909 ** compilation of the PRAGMA fails with an error. ^The [SQLITE_FCNTL_PRAGMA]
910 ** file control occurs at the beginning of pragma statement analysis and so
911 ** it is able to override built-in [PRAGMA] statements.
912 **
913 ** <li>[[SQLITE_FCNTL_BUSYHANDLER]]
914 ** ^The [SQLITE_FCNTL_BUSYHANDLER]
915 ** file-control may be invoked by SQLite on the database file handle
916 ** shortly after it is opened in order to provide a custom VFS with access
917 ** to the connections busy-handler callback. The argument is of type (void **)
918 ** - an array of two (void *) values. The first (void *) actually points
919 ** to a function of type (int (*)(void *)). In order to invoke the connections
920 ** busy-handler, this function should be invoked with the second (void *) in
921 ** the array as the only argument. If it returns non-zero, then the operation
922 ** should be retried. If it returns zero, the custom VFS should abandon the
923 ** current operation.
924 **
925 ** <li>[[SQLITE_FCNTL_TEMPFILENAME]]
926 ** ^Application can invoke the [SQLITE_FCNTL_TEMPFILENAME] file-control
927 ** to have SQLite generate a
928 ** temporary filename using the same algorithm that is followed to generate
929 ** temporary filenames for TEMP tables and other internal uses. The
930 ** argument should be a char** which will be filled with the filename
931 ** written into memory obtained from [sqlite3_malloc()]. The caller should
932 ** invoke [sqlite3_free()] on the result to avoid a memory leak.
933 **
934 ** <li>[[SQLITE_FCNTL_MMAP_SIZE]]
935 ** The [SQLITE_FCNTL_MMAP_SIZE] file control is used to query or set the
936 ** maximum number of bytes that will be used for memory-mapped I/O.
937 ** The argument is a pointer to a value of type sqlite3_int64 that
938 ** is an advisory maximum number of bytes in the file to memory map. The
939 ** pointer is overwritten with the old value. The limit is not changed if
940 ** the value originally pointed to is negative, and so the current limit
941 ** can be queried by passing in a pointer to a negative number. This
942 ** file-control is used internally to implement [PRAGMA mmap_size].
943 **
944 ** <li>[[SQLITE_FCNTL_TRACE]]
945 ** The [SQLITE_FCNTL_TRACE] file control provides advisory information
946 ** to the VFS about what the higher layers of the SQLite stack are doing.
947 ** This file control is used by some VFS activity tracing [shims].
948 ** The argument is a zero-terminated string. Higher layers in the
949 ** SQLite stack may generate instances of this file control if
950 ** the [SQLITE_USE_FCNTL_TRACE] compile-time option is enabled.
951 **
952 ** </ul>
953 */
954 #define SQLITE_FCNTL_LOCKSTATE 1
955 #define SQLITE_GET_LOCKPROXYFILE 2
956 #define SQLITE_SET_LOCKPROXYFILE 3
957 #define SQLITE_LAST_ERRNO 4
958 #define SQLITE_FCNTL_SIZE_HINT 5
959 #define SQLITE_FCNTL_CHUNK_SIZE 6
960 #define SQLITE_FCNTL_FILE_POINTER 7
961 #define SQLITE_FCNTL_SYNC_OMITTED 8
962 #define SQLITE_FCNTL_WIN32_AV_RETRY 9
963 #define SQLITE_FCNTL_PERSIST_WAL 10
964 #define SQLITE_FCNTL_OVERWRITE 11
965 #define SQLITE_FCNTL_VFSNAME 12
966 #define SQLITE_FCNTL_POWERSAFE_OVERWRITE 13
967 #define SQLITE_FCNTL_PRAGMA 14
968 #define SQLITE_FCNTL_BUSYHANDLER 15
969 #define SQLITE_FCNTL_TEMPFILENAME 16
970 #define SQLITE_FCNTL_MMAP_SIZE 18
971 #define SQLITE_FCNTL_TRACE 19
972 
973 /*
974 ** CAPI3REF: Mutex Handle
975 **
976 ** The mutex module within SQLite defines [sqlite3_mutex] to be an
977 ** abstract type for a mutex object. The SQLite core never looks
978 ** at the internal representation of an [sqlite3_mutex]. It only
979 ** deals with pointers to the [sqlite3_mutex] object.
980 **
981 ** Mutexes are created using [sqlite3_mutex_alloc()].
982 */
984 
985 /*
986 ** CAPI3REF: OS Interface Object
987 **
988 ** An instance of the sqlite3_vfs object defines the interface between
989 ** the SQLite core and the underlying operating system. The "vfs"
990 ** in the name of the object stands for "virtual file system". See
991 ** the [VFS | VFS documentation] for further information.
992 **
993 ** The value of the iVersion field is initially 1 but may be larger in
994 ** future versions of SQLite. Additional fields may be appended to this
995 ** object when the iVersion value is increased. Note that the structure
996 ** of the sqlite3_vfs object changes in the transaction between
997 ** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not
998 ** modified.
999 **
1000 ** The szOsFile field is the size of the subclassed [sqlite3_file]
1001 ** structure used by this VFS. mxPathname is the maximum length of
1002 ** a pathname in this VFS.
1003 **
1004 ** Registered sqlite3_vfs objects are kept on a linked list formed by
1005 ** the pNext pointer. The [sqlite3_vfs_register()]
1006 ** and [sqlite3_vfs_unregister()] interfaces manage this list
1007 ** in a thread-safe way. The [sqlite3_vfs_find()] interface
1008 ** searches the list. Neither the application code nor the VFS
1009 ** implementation should use the pNext pointer.
1010 **
1011 ** The pNext field is the only field in the sqlite3_vfs
1012 ** structure that SQLite will ever modify. SQLite will only access
1013 ** or modify this field while holding a particular static mutex.
1014 ** The application should never modify anything within the sqlite3_vfs
1015 ** object once the object has been registered.
1016 **
1017 ** The zName field holds the name of the VFS module. The name must
1018 ** be unique across all VFS modules.
1019 **
1020 ** [[sqlite3_vfs.xOpen]]
1021 ** ^SQLite guarantees that the zFilename parameter to xOpen
1022 ** is either a NULL pointer or string obtained
1023 ** from xFullPathname() with an optional suffix added.
1024 ** ^If a suffix is added to the zFilename parameter, it will
1025 ** consist of a single "-" character followed by no more than
1026 ** 11 alphanumeric and/or "-" characters.
1027 ** ^SQLite further guarantees that
1028 ** the string will be valid and unchanged until xClose() is
1029 ** called. Because of the previous sentence,
1030 ** the [sqlite3_file] can safely store a pointer to the
1031 ** filename if it needs to remember the filename for some reason.
1032 ** If the zFilename parameter to xOpen is a NULL pointer then xOpen
1033 ** must invent its own temporary name for the file. ^Whenever the
1034 ** xFilename parameter is NULL it will also be the case that the
1035 ** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
1036 **
1037 ** The flags argument to xOpen() includes all bits set in
1038 ** the flags argument to [sqlite3_open_v2()]. Or if [sqlite3_open()]
1039 ** or [sqlite3_open16()] is used, then flags includes at least
1040 ** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE].
1041 ** If xOpen() opens a file read-only then it sets *pOutFlags to
1042 ** include [SQLITE_OPEN_READONLY]. Other bits in *pOutFlags may be set.
1043 **
1044 ** ^(SQLite will also add one of the following flags to the xOpen()
1045 ** call, depending on the object being opened:
1046 **
1047 ** <ul>
1048 ** <li> [SQLITE_OPEN_MAIN_DB]
1049 ** <li> [SQLITE_OPEN_MAIN_JOURNAL]
1050 ** <li> [SQLITE_OPEN_TEMP_DB]
1051 ** <li> [SQLITE_OPEN_TEMP_JOURNAL]
1052 ** <li> [SQLITE_OPEN_TRANSIENT_DB]
1053 ** <li> [SQLITE_OPEN_SUBJOURNAL]
1054 ** <li> [SQLITE_OPEN_MASTER_JOURNAL]
1055 ** <li> [SQLITE_OPEN_WAL]
1056 ** </ul>)^
1057 **
1058 ** The file I/O implementation can use the object type flags to
1059 ** change the way it deals with files. For example, an application
1060 ** that does not care about crash recovery or rollback might make
1061 ** the open of a journal file a no-op. Writes to this journal would
1062 ** also be no-ops, and any attempt to read the journal would return
1063 ** SQLITE_IOERR. Or the implementation might recognize that a database
1064 ** file will be doing page-aligned sector reads and writes in a random
1065 ** order and set up its I/O subsystem accordingly.
1066 **
1067 ** SQLite might also add one of the following flags to the xOpen method:
1068 **
1069 ** <ul>
1070 ** <li> [SQLITE_OPEN_DELETEONCLOSE]
1071 ** <li> [SQLITE_OPEN_EXCLUSIVE]
1072 ** </ul>
1073 **
1074 ** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
1075 ** deleted when it is closed. ^The [SQLITE_OPEN_DELETEONCLOSE]
1076 ** will be set for TEMP databases and their journals, transient
1077 ** databases, and subjournals.
1078 **
1079 ** ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction
1080 ** with the [SQLITE_OPEN_CREATE] flag, which are both directly
1081 ** analogous to the O_EXCL and O_CREAT flags of the POSIX open()
1082 ** API. The SQLITE_OPEN_EXCLUSIVE flag, when paired with the
1083 ** SQLITE_OPEN_CREATE, is used to indicate that file should always
1084 ** be created, and that it is an error if it already exists.
1085 ** It is <i>not</i> used to indicate the file should be opened
1086 ** for exclusive access.
1087 **
1088 ** ^At least szOsFile bytes of memory are allocated by SQLite
1089 ** to hold the [sqlite3_file] structure passed as the third
1090 ** argument to xOpen. The xOpen method does not have to
1091 ** allocate the structure; it should just fill it in. Note that
1092 ** the xOpen method must set the sqlite3_file.pMethods to either
1093 ** a valid [sqlite3_io_methods] object or to NULL. xOpen must do
1094 ** this even if the open fails. SQLite expects that the sqlite3_file.pMethods
1095 ** element will be valid after xOpen returns regardless of the success
1096 ** or failure of the xOpen call.
1097 **
1098 ** [[sqlite3_vfs.xAccess]]
1099 ** ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
1100 ** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
1101 ** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
1102 ** to test whether a file is at least readable. The file can be a
1103 ** directory.
1104 **
1105 ** ^SQLite will always allocate at least mxPathname+1 bytes for the
1106 ** output buffer xFullPathname. The exact size of the output buffer
1107 ** is also passed as a parameter to both methods. If the output buffer
1108 ** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
1109 ** handled as a fatal error by SQLite, vfs implementations should endeavor
1110 ** to prevent this by setting mxPathname to a sufficiently large value.
1111 **
1112 ** The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64()
1113 ** interfaces are not strictly a part of the filesystem, but they are
1114 ** included in the VFS structure for completeness.
1115 ** The xRandomness() function attempts to return nBytes bytes
1116 ** of good-quality randomness into zOut. The return value is
1117 ** the actual number of bytes of randomness obtained.
1118 ** The xSleep() method causes the calling thread to sleep for at
1119 ** least the number of microseconds given. ^The xCurrentTime()
1120 ** method returns a Julian Day Number for the current date and time as
1121 ** a floating point value.
1122 ** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
1123 ** Day Number multiplied by 86400000 (the number of milliseconds in
1124 ** a 24-hour day).
1125 ** ^SQLite will use the xCurrentTimeInt64() method to get the current
1126 ** date and time if that method is available (if iVersion is 2 or
1127 ** greater and the function pointer is not NULL) and will fall back
1128 ** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
1129 **
1130 ** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
1131 ** are not used by the SQLite core. These optional interfaces are provided
1132 ** by some VFSes to facilitate testing of the VFS code. By overriding
1133 ** system calls with functions under its control, a test program can
1134 ** simulate faults and error conditions that would otherwise be difficult
1135 ** or impossible to induce. The set of system calls that can be overridden
1136 ** varies from one VFS to another, and from one version of the same VFS to the
1137 ** next. Applications that use these interfaces must be prepared for any
1138 ** or all of these interfaces to be NULL or for their behavior to change
1139 ** from one release to the next. Applications must not attempt to access
1140 ** any of these methods if the iVersion of the VFS is less than 3.
1141 */
1142 typedef struct sqlite3_vfs sqlite3_vfs;
1143 typedef void (*sqlite3_syscall_ptr)(void);
1144 struct sqlite3_vfs {
1145  int iVersion; /* Structure version number (currently 3) */
1146  int szOsFile; /* Size of subclassed sqlite3_file */
1147  int mxPathname; /* Maximum file pathname length */
1148  sqlite3_vfs *pNext; /* Next registered VFS */
1149  const char *zName; /* Name of this virtual file system */
1150  void *pAppData; /* Pointer to application-specific data */
1151  int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
1152  int flags, int *pOutFlags);
1153  int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
1154  int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
1155  int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
1156  void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
1157  void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
1158  void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
1159  void (*xDlClose)(sqlite3_vfs*, void*);
1160  int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
1161  int (*xSleep)(sqlite3_vfs*, int microseconds);
1162  int (*xCurrentTime)(sqlite3_vfs*, double*);
1163  int (*xGetLastError)(sqlite3_vfs*, int, char *);
1164  /*
1165  ** The methods above are in version 1 of the sqlite_vfs object
1166  ** definition. Those that follow are added in version 2 or later
1167  */
1168  int (*xCurrentTimeInt64)(sqlite3_vfs*, sqlite3_int64*);
1169  /*
1170  ** The methods above are in versions 1 and 2 of the sqlite_vfs object.
1171  ** Those below are for version 3 and greater.
1172  */
1173  int (*xSetSystemCall)(sqlite3_vfs*, const char *zName, sqlite3_syscall_ptr);
1174  sqlite3_syscall_ptr (*xGetSystemCall)(sqlite3_vfs*, const char *zName);
1175  const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
1176  /*
1177  ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
1178  ** New fields may be appended in figure versions. The iVersion
1179  ** value will increment whenever this happens.
1180  */
1181 };
1182 
1183 /*
1184 ** CAPI3REF: Flags for the xAccess VFS method
1185 **
1186 ** These integer constants can be used as the third parameter to
1187 ** the xAccess method of an [sqlite3_vfs] object. They determine
1188 ** what kind of permissions the xAccess method is looking for.
1189 ** With SQLITE_ACCESS_EXISTS, the xAccess method
1190 ** simply checks whether the file exists.
1191 ** With SQLITE_ACCESS_READWRITE, the xAccess method
1192 ** checks whether the named directory is both readable and writable
1193 ** (in other words, if files can be added, removed, and renamed within
1194 ** the directory).
1195 ** The SQLITE_ACCESS_READWRITE constant is currently used only by the
1196 ** [temp_store_directory pragma], though this could change in a future
1197 ** release of SQLite.
1198 ** With SQLITE_ACCESS_READ, the xAccess method
1199 ** checks whether the file is readable. The SQLITE_ACCESS_READ constant is
1200 ** currently unused, though it might be used in a future release of
1201 ** SQLite.
1202 */
1203 #define SQLITE_ACCESS_EXISTS 0
1204 #define SQLITE_ACCESS_READWRITE 1 /* Used by PRAGMA temp_store_directory */
1205 #define SQLITE_ACCESS_READ 2 /* Unused */
1206 
1207 /*
1208 ** CAPI3REF: Flags for the xShmLock VFS method
1209 **
1210 ** These integer constants define the various locking operations
1211 ** allowed by the xShmLock method of [sqlite3_io_methods]. The
1212 ** following are the only legal combinations of flags to the
1213 ** xShmLock method:
1214 **
1215 ** <ul>
1216 ** <li> SQLITE_SHM_LOCK | SQLITE_SHM_SHARED
1217 ** <li> SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE
1218 ** <li> SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED
1219 ** <li> SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE
1220 ** </ul>
1221 **
1222 ** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
1223 ** was given no the corresponding lock.
1224 **
1225 ** The xShmLock method can transition between unlocked and SHARED or
1226 ** between unlocked and EXCLUSIVE. It cannot transition between SHARED
1227 ** and EXCLUSIVE.
1228 */
1229 #define SQLITE_SHM_UNLOCK 1
1230 #define SQLITE_SHM_LOCK 2
1231 #define SQLITE_SHM_SHARED 4
1232 #define SQLITE_SHM_EXCLUSIVE 8
1233 
1234 /*
1235 ** CAPI3REF: Maximum xShmLock index
1236 **
1237 ** The xShmLock method on [sqlite3_io_methods] may use values
1238 ** between 0 and this upper bound as its "offset" argument.
1239 ** The SQLite core will never attempt to acquire or release a
1240 ** lock outside of this range
1241 */
1242 #define SQLITE_SHM_NLOCK 8
1243 
1244 
1245 /*
1246 ** CAPI3REF: Initialize The SQLite Library
1247 **
1248 ** ^The sqlite3_initialize() routine initializes the
1249 ** SQLite library. ^The sqlite3_shutdown() routine
1250 ** deallocates any resources that were allocated by sqlite3_initialize().
1251 ** These routines are designed to aid in process initialization and
1252 ** shutdown on embedded systems. Workstation applications using
1253 ** SQLite normally do not need to invoke either of these routines.
1254 **
1255 ** A call to sqlite3_initialize() is an "effective" call if it is
1256 ** the first time sqlite3_initialize() is invoked during the lifetime of
1257 ** the process, or if it is the first time sqlite3_initialize() is invoked
1258 ** following a call to sqlite3_shutdown(). ^(Only an effective call
1259 ** of sqlite3_initialize() does any initialization. All other calls
1260 ** are harmless no-ops.)^
1261 **
1262 ** A call to sqlite3_shutdown() is an "effective" call if it is the first
1263 ** call to sqlite3_shutdown() since the last sqlite3_initialize(). ^(Only
1264 ** an effective call to sqlite3_shutdown() does any deinitialization.
1265 ** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^
1266 **
1267 ** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()
1268 ** is not. The sqlite3_shutdown() interface must only be called from a
1269 ** single thread. All open [database connections] must be closed and all
1270 ** other SQLite resources must be deallocated prior to invoking
1271 ** sqlite3_shutdown().
1272 **
1273 ** Among other things, ^sqlite3_initialize() will invoke
1274 ** sqlite3_os_init(). Similarly, ^sqlite3_shutdown()
1275 ** will invoke sqlite3_os_end().
1276 **
1277 ** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.
1278 ** ^If for some reason, sqlite3_initialize() is unable to initialize
1279 ** the library (perhaps it is unable to allocate a needed resource such
1280 ** as a mutex) it returns an [error code] other than [SQLITE_OK].
1281 **
1282 ** ^The sqlite3_initialize() routine is called internally by many other
1283 ** SQLite interfaces so that an application usually does not need to
1284 ** invoke sqlite3_initialize() directly. For example, [sqlite3_open()]
1285 ** calls sqlite3_initialize() so the SQLite library will be automatically
1286 ** initialized when [sqlite3_open()] is called if it has not be initialized
1287 ** already. ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
1288 ** compile-time option, then the automatic calls to sqlite3_initialize()
1289 ** are omitted and the application must call sqlite3_initialize() directly
1290 ** prior to using any other SQLite interface. For maximum portability,
1291 ** it is recommended that applications always invoke sqlite3_initialize()
1292 ** directly prior to using any other SQLite interface. Future releases
1293 ** of SQLite may require this. In other words, the behavior exhibited
1294 ** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
1295 ** default behavior in some future release of SQLite.
1296 **
1297 ** The sqlite3_os_init() routine does operating-system specific
1298 ** initialization of the SQLite library. The sqlite3_os_end()
1299 ** routine undoes the effect of sqlite3_os_init(). Typical tasks
1300 ** performed by these routines include allocation or deallocation
1301 ** of static resources, initialization of global variables,
1302 ** setting up a default [sqlite3_vfs] module, or setting up
1303 ** a default configuration using [sqlite3_config()].
1304 **
1305 ** The application should never invoke either sqlite3_os_init()
1306 ** or sqlite3_os_end() directly. The application should only invoke
1307 ** sqlite3_initialize() and sqlite3_shutdown(). The sqlite3_os_init()
1308 ** interface is called automatically by sqlite3_initialize() and
1309 ** sqlite3_os_end() is called by sqlite3_shutdown(). Appropriate
1310 ** implementations for sqlite3_os_init() and sqlite3_os_end()
1311 ** are built into SQLite when it is compiled for Unix, Windows, or OS/2.
1312 ** When [custom builds | built for other platforms]
1313 ** (using the [SQLITE_OS_OTHER=1] compile-time
1314 ** option) the application must supply a suitable implementation for
1315 ** sqlite3_os_init() and sqlite3_os_end(). An application-supplied
1316 ** implementation of sqlite3_os_init() or sqlite3_os_end()
1317 ** must return [SQLITE_OK] on success and some other [error code] upon
1318 ** failure.
1319 */
1320 SQLITE_API int sqlite3_initialize(void);
1321 SQLITE_API int sqlite3_shutdown(void);
1322 SQLITE_API int sqlite3_os_init(void);
1323 SQLITE_API int sqlite3_os_end(void);
1324 
1325 /*
1326 ** CAPI3REF: Configuring The SQLite Library
1327 **
1328 ** The sqlite3_config() interface is used to make global configuration
1329 ** changes to SQLite in order to tune SQLite to the specific needs of
1330 ** the application. The default configuration is recommended for most
1331 ** applications and so this routine is usually not necessary. It is
1332 ** provided to support rare applications with unusual needs.
1333 **
1334 ** The sqlite3_config() interface is not threadsafe. The application
1335 ** must insure that no other SQLite interfaces are invoked by other
1336 ** threads while sqlite3_config() is running. Furthermore, sqlite3_config()
1337 ** may only be invoked prior to library initialization using
1338 ** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
1339 ** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
1340 ** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.
1341 ** Note, however, that ^sqlite3_config() can be called as part of the
1342 ** implementation of an application-defined [sqlite3_os_init()].
1343 **
1344 ** The first argument to sqlite3_config() is an integer
1345 ** [configuration option] that determines
1346 ** what property of SQLite is to be configured. Subsequent arguments
1347 ** vary depending on the [configuration option]
1348 ** in the first argument.
1349 **
1350 ** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
1351 ** ^If the option is unknown or SQLite is unable to set the option
1352 ** then this routine returns a non-zero [error code].
1353 */
1354 SQLITE_API int sqlite3_config(int, ...);
1355 
1356 /*
1357 ** CAPI3REF: Configure database connections
1358 **
1359 ** The sqlite3_db_config() interface is used to make configuration
1360 ** changes to a [database connection]. The interface is similar to
1361 ** [sqlite3_config()] except that the changes apply to a single
1362 ** [database connection] (specified in the first argument).
1363 **
1364 ** The second argument to sqlite3_db_config(D,V,...) is the
1365 ** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code
1366 ** that indicates what aspect of the [database connection] is being configured.
1367 ** Subsequent arguments vary depending on the configuration verb.
1368 **
1369 ** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
1370 ** the call is considered successful.
1371 */
1372 SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);
1373 
1374 /*
1375 ** CAPI3REF: Memory Allocation Routines
1376 **
1377 ** An instance of this object defines the interface between SQLite
1378 ** and low-level memory allocation routines.
1379 **
1380 ** This object is used in only one place in the SQLite interface.
1381 ** A pointer to an instance of this object is the argument to
1382 ** [sqlite3_config()] when the configuration option is
1383 ** [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC].
1384 ** By creating an instance of this object
1385 ** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])
1386 ** during configuration, an application can specify an alternative
1387 ** memory allocation subsystem for SQLite to use for all of its
1388 ** dynamic memory needs.
1389 **
1390 ** Note that SQLite comes with several [built-in memory allocators]
1391 ** that are perfectly adequate for the overwhelming majority of applications
1392 ** and that this object is only useful to a tiny minority of applications
1393 ** with specialized memory allocation requirements. This object is
1394 ** also used during testing of SQLite in order to specify an alternative
1395 ** memory allocator that simulates memory out-of-memory conditions in
1396 ** order to verify that SQLite recovers gracefully from such
1397 ** conditions.
1398 **
1399 ** The xMalloc, xRealloc, and xFree methods must work like the
1400 ** malloc(), realloc() and free() functions from the standard C library.
1401 ** ^SQLite guarantees that the second argument to
1402 ** xRealloc is always a value returned by a prior call to xRoundup.
1403 **
1404 ** xSize should return the allocated size of a memory allocation
1405 ** previously obtained from xMalloc or xRealloc. The allocated size
1406 ** is always at least as big as the requested size but may be larger.
1407 **
1408 ** The xRoundup method returns what would be the allocated size of
1409 ** a memory allocation given a particular requested size. Most memory
1410 ** allocators round up memory allocations at least to the next multiple
1411 ** of 8. Some allocators round up to a larger multiple or to a power of 2.
1412 ** Every memory allocation request coming in through [sqlite3_malloc()]
1413 ** or [sqlite3_realloc()] first calls xRoundup. If xRoundup returns 0,
1414 ** that causes the corresponding memory allocation to fail.
1415 **
1416 ** The xInit method initializes the memory allocator. For example,
1417 ** it might allocate any require mutexes or initialize internal data
1418 ** structures. The xShutdown method is invoked (indirectly) by
1419 ** [sqlite3_shutdown()] and should deallocate any resources acquired
1420 ** by xInit. The pAppData pointer is used as the only parameter to
1421 ** xInit and xShutdown.
1422 **
1423 ** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes
1424 ** the xInit method, so the xInit method need not be threadsafe. The
1425 ** xShutdown method is only called from [sqlite3_shutdown()] so it does
1426 ** not need to be threadsafe either. For all other methods, SQLite
1427 ** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the
1428 ** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which
1429 ** it is by default) and so the methods are automatically serialized.
1430 ** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other
1431 ** methods must be threadsafe or else make their own arrangements for
1432 ** serialization.
1433 **
1434 ** SQLite will never invoke xInit() more than once without an intervening
1435 ** call to xShutdown().
1436 */
1439  void *(*xMalloc)(int); /* Memory allocation function */
1440  void (*xFree)(void*); /* Free a prior allocation */
1441  void *(*xRealloc)(void*,int); /* Resize an allocation */
1442  int (*xSize)(void*); /* Return the size of an allocation */
1443  int (*xRoundup)(int); /* Round up request size to allocation size */
1444  int (*xInit)(void*); /* Initialize the memory allocator */
1445  void (*xShutdown)(void*); /* Deinitialize the memory allocator */
1446  void *pAppData; /* Argument to xInit() and xShutdown() */
1447 };
1448 
1449 /*
1450 ** CAPI3REF: Configuration Options
1451 ** KEYWORDS: {configuration option}
1452 **
1453 ** These constants are the available integer configuration options that
1454 ** can be passed as the first argument to the [sqlite3_config()] interface.
1455 **
1456 ** New configuration options may be added in future releases of SQLite.
1457 ** Existing configuration options might be discontinued. Applications
1458 ** should check the return code from [sqlite3_config()] to make sure that
1459 ** the call worked. The [sqlite3_config()] interface will return a
1460 ** non-zero [error code] if a discontinued or unsupported configuration option
1461 ** is invoked.
1462 **
1463 ** <dl>
1464 ** [[SQLITE_CONFIG_SINGLETHREAD]] <dt>SQLITE_CONFIG_SINGLETHREAD</dt>
1465 ** <dd>There are no arguments to this option. ^This option sets the
1466 ** [threading mode] to Single-thread. In other words, it disables
1467 ** all mutexing and puts SQLite into a mode where it can only be used
1468 ** by a single thread. ^If SQLite is compiled with
1469 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1470 ** it is not possible to change the [threading mode] from its default
1471 ** value of Single-thread and so [sqlite3_config()] will return
1472 ** [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD
1473 ** configuration option.</dd>
1474 **
1475 ** [[SQLITE_CONFIG_MULTITHREAD]] <dt>SQLITE_CONFIG_MULTITHREAD</dt>
1476 ** <dd>There are no arguments to this option. ^This option sets the
1477 ** [threading mode] to Multi-thread. In other words, it disables
1478 ** mutexing on [database connection] and [prepared statement] objects.
1479 ** The application is responsible for serializing access to
1480 ** [database connections] and [prepared statements]. But other mutexes
1481 ** are enabled so that SQLite will be safe to use in a multi-threaded
1482 ** environment as long as no two threads attempt to use the same
1483 ** [database connection] at the same time. ^If SQLite is compiled with
1484 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1485 ** it is not possible to set the Multi-thread [threading mode] and
1486 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
1487 ** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>
1488 **
1489 ** [[SQLITE_CONFIG_SERIALIZED]] <dt>SQLITE_CONFIG_SERIALIZED</dt>
1490 ** <dd>There are no arguments to this option. ^This option sets the
1491 ** [threading mode] to Serialized. In other words, this option enables
1492 ** all mutexes including the recursive
1493 ** mutexes on [database connection] and [prepared statement] objects.
1494 ** In this mode (which is the default when SQLite is compiled with
1495 ** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
1496 ** to [database connections] and [prepared statements] so that the
1497 ** application is free to use the same [database connection] or the
1498 ** same [prepared statement] in different threads at the same time.
1499 ** ^If SQLite is compiled with
1500 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1501 ** it is not possible to set the Serialized [threading mode] and
1502 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
1503 ** SQLITE_CONFIG_SERIALIZED configuration option.</dd>
1504 **
1505 ** [[SQLITE_CONFIG_MALLOC]] <dt>SQLITE_CONFIG_MALLOC</dt>
1506 ** <dd> ^(This option takes a single argument which is a pointer to an
1507 ** instance of the [sqlite3_mem_methods] structure. The argument specifies
1508 ** alternative low-level memory allocation routines to be used in place of
1509 ** the memory allocation routines built into SQLite.)^ ^SQLite makes
1510 ** its own private copy of the content of the [sqlite3_mem_methods] structure
1511 ** before the [sqlite3_config()] call returns.</dd>
1512 **
1513 ** [[SQLITE_CONFIG_GETMALLOC]] <dt>SQLITE_CONFIG_GETMALLOC</dt>
1514 ** <dd> ^(This option takes a single argument which is a pointer to an
1515 ** instance of the [sqlite3_mem_methods] structure. The [sqlite3_mem_methods]
1516 ** structure is filled with the currently defined memory allocation routines.)^
1517 ** This option can be used to overload the default memory allocation
1518 ** routines with a wrapper that simulations memory allocation failure or
1519 ** tracks memory usage, for example. </dd>
1520 **
1521 ** [[SQLITE_CONFIG_MEMSTATUS]] <dt>SQLITE_CONFIG_MEMSTATUS</dt>
1522 ** <dd> ^This option takes single argument of type int, interpreted as a
1523 ** boolean, which enables or disables the collection of memory allocation
1524 ** statistics. ^(When memory allocation statistics are disabled, the
1525 ** following SQLite interfaces become non-operational:
1526 ** <ul>
1527 ** <li> [sqlite3_memory_used()]
1528 ** <li> [sqlite3_memory_highwater()]
1529 ** <li> [sqlite3_soft_heap_limit64()]
1530 ** <li> [sqlite3_status()]
1531 ** </ul>)^
1532 ** ^Memory allocation statistics are enabled by default unless SQLite is
1533 ** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
1534 ** allocation statistics are disabled by default.
1535 ** </dd>
1536 **
1537 ** [[SQLITE_CONFIG_SCRATCH]] <dt>SQLITE_CONFIG_SCRATCH</dt>
1538 ** <dd> ^This option specifies a static memory buffer that SQLite can use for
1539 ** scratch memory. There are three arguments: A pointer an 8-byte
1540 ** aligned memory buffer from which the scratch allocations will be
1541 ** drawn, the size of each scratch allocation (sz),
1542 ** and the maximum number of scratch allocations (N). The sz
1543 ** argument must be a multiple of 16.
1544 ** The first argument must be a pointer to an 8-byte aligned buffer
1545 ** of at least sz*N bytes of memory.
1546 ** ^SQLite will use no more than two scratch buffers per thread. So
1547 ** N should be set to twice the expected maximum number of threads.
1548 ** ^SQLite will never require a scratch buffer that is more than 6
1549 ** times the database page size. ^If SQLite needs needs additional
1550 ** scratch memory beyond what is provided by this configuration option, then
1551 ** [sqlite3_malloc()] will be used to obtain the memory needed.</dd>
1552 **
1553 ** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
1554 ** <dd> ^This option specifies a static memory buffer that SQLite can use for
1555 ** the database page cache with the default page cache implementation.
1556 ** This configuration should not be used if an application-define page
1557 ** cache implementation is loaded using the SQLITE_CONFIG_PCACHE2 option.
1558 ** There are three arguments to this option: A pointer to 8-byte aligned
1559 ** memory, the size of each page buffer (sz), and the number of pages (N).
1560 ** The sz argument should be the size of the largest database page
1561 ** (a power of two between 512 and 32768) plus a little extra for each
1562 ** page header. ^The page header size is 20 to 40 bytes depending on
1563 ** the host architecture. ^It is harmless, apart from the wasted memory,
1564 ** to make sz a little too large. The first
1565 ** argument should point to an allocation of at least sz*N bytes of memory.
1566 ** ^SQLite will use the memory provided by the first argument to satisfy its
1567 ** memory needs for the first N pages that it adds to cache. ^If additional
1568 ** page cache memory is needed beyond what is provided by this option, then
1569 ** SQLite goes to [sqlite3_malloc()] for the additional storage space.
1570 ** The pointer in the first argument must
1571 ** be aligned to an 8-byte boundary or subsequent behavior of SQLite
1572 ** will be undefined.</dd>
1573 **
1574 ** [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt>
1575 ** <dd> ^This option specifies a static memory buffer that SQLite will use
1576 ** for all of its dynamic memory allocation needs beyond those provided
1577 ** for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE].
1578 ** There are three arguments: An 8-byte aligned pointer to the memory,
1579 ** the number of bytes in the memory buffer, and the minimum allocation size.
1580 ** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
1581 ** to using its default memory allocator (the system malloc() implementation),
1582 ** undoing any prior invocation of [SQLITE_CONFIG_MALLOC]. ^If the
1583 ** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
1584 ** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
1585 ** allocator is engaged to handle all of SQLites memory allocation needs.
1586 ** The first pointer (the memory pointer) must be aligned to an 8-byte
1587 ** boundary or subsequent behavior of SQLite will be undefined.
1588 ** The minimum allocation size is capped at 2**12. Reasonable values
1589 ** for the minimum allocation size are 2**5 through 2**8.</dd>
1590 **
1591 ** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
1592 ** <dd> ^(This option takes a single argument which is a pointer to an
1593 ** instance of the [sqlite3_mutex_methods] structure. The argument specifies
1594 ** alternative low-level mutex routines to be used in place
1595 ** the mutex routines built into SQLite.)^ ^SQLite makes a copy of the
1596 ** content of the [sqlite3_mutex_methods] structure before the call to
1597 ** [sqlite3_config()] returns. ^If SQLite is compiled with
1598 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1599 ** the entire mutexing subsystem is omitted from the build and hence calls to
1600 ** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
1601 ** return [SQLITE_ERROR].</dd>
1602 **
1603 ** [[SQLITE_CONFIG_GETMUTEX]] <dt>SQLITE_CONFIG_GETMUTEX</dt>
1604 ** <dd> ^(This option takes a single argument which is a pointer to an
1605 ** instance of the [sqlite3_mutex_methods] structure. The
1606 ** [sqlite3_mutex_methods]
1607 ** structure is filled with the currently defined mutex routines.)^
1608 ** This option can be used to overload the default mutex allocation
1609 ** routines with a wrapper used to track mutex usage for performance
1610 ** profiling or testing, for example. ^If SQLite is compiled with
1611 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1612 ** the entire mutexing subsystem is omitted from the build and hence calls to
1613 ** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will
1614 ** return [SQLITE_ERROR].</dd>
1615 **
1616 ** [[SQLITE_CONFIG_LOOKASIDE]] <dt>SQLITE_CONFIG_LOOKASIDE</dt>
1617 ** <dd> ^(This option takes two arguments that determine the default
1618 ** memory allocation for the lookaside memory allocator on each
1619 ** [database connection]. The first argument is the
1620 ** size of each lookaside buffer slot and the second is the number of
1621 ** slots allocated to each database connection.)^ ^(This option sets the
1622 ** <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]
1623 ** verb to [sqlite3_db_config()] can be used to change the lookaside
1624 ** configuration on individual connections.)^ </dd>
1625 **
1626 ** [[SQLITE_CONFIG_PCACHE2]] <dt>SQLITE_CONFIG_PCACHE2</dt>
1627 ** <dd> ^(This option takes a single argument which is a pointer to
1628 ** an [sqlite3_pcache_methods2] object. This object specifies the interface
1629 ** to a custom page cache implementation.)^ ^SQLite makes a copy of the
1630 ** object and uses it for page cache memory allocations.</dd>
1631 **
1632 ** [[SQLITE_CONFIG_GETPCACHE2]] <dt>SQLITE_CONFIG_GETPCACHE2</dt>
1633 ** <dd> ^(This option takes a single argument which is a pointer to an
1634 ** [sqlite3_pcache_methods2] object. SQLite copies of the current
1635 ** page cache implementation into that object.)^ </dd>
1636 **
1637 ** [[SQLITE_CONFIG_LOG]] <dt>SQLITE_CONFIG_LOG</dt>
1638 ** <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite
1639 ** global [error log].
1640 ** (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
1641 ** function with a call signature of void(*)(void*,int,const char*),
1642 ** and a pointer to void. ^If the function pointer is not NULL, it is
1643 ** invoked by [sqlite3_log()] to process each logging event. ^If the
1644 ** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
1645 ** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
1646 ** passed through as the first parameter to the application-defined logger
1647 ** function whenever that function is invoked. ^The second parameter to
1648 ** the logger function is a copy of the first parameter to the corresponding
1649 ** [sqlite3_log()] call and is intended to be a [result code] or an
1650 ** [extended result code]. ^The third parameter passed to the logger is
1651 ** log message after formatting via [sqlite3_snprintf()].
1652 ** The SQLite logging interface is not reentrant; the logger function
1653 ** supplied by the application must not invoke any SQLite interface.
1654 ** In a multi-threaded application, the application-defined logger
1655 ** function must be threadsafe. </dd>
1656 **
1657 ** [[SQLITE_CONFIG_URI]] <dt>SQLITE_CONFIG_URI
1658 ** <dd>^(This option takes a single argument of type int. If non-zero, then
1659 ** URI handling is globally enabled. If the parameter is zero, then URI handling
1660 ** is globally disabled.)^ ^If URI handling is globally enabled, all filenames
1661 ** passed to [sqlite3_open()], [sqlite3_open_v2()], [sqlite3_open16()] or
1662 ** specified as part of [ATTACH] commands are interpreted as URIs, regardless
1663 ** of whether or not the [SQLITE_OPEN_URI] flag is set when the database
1664 ** connection is opened. ^If it is globally disabled, filenames are
1665 ** only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the
1666 ** database connection is opened. ^(By default, URI handling is globally
1667 ** disabled. The default value may be changed by compiling with the
1668 ** [SQLITE_USE_URI] symbol defined.)^
1669 **
1670 ** [[SQLITE_CONFIG_COVERING_INDEX_SCAN]] <dt>SQLITE_CONFIG_COVERING_INDEX_SCAN
1671 ** <dd>^This option takes a single integer argument which is interpreted as
1672 ** a boolean in order to enable or disable the use of covering indices for
1673 ** full table scans in the query optimizer. ^The default setting is determined
1674 ** by the [SQLITE_ALLOW_COVERING_INDEX_SCAN] compile-time option, or is "on"
1675 ** if that compile-time option is omitted.
1676 ** The ability to disable the use of covering indices for full table scans
1677 ** is because some incorrectly coded legacy applications might malfunction
1678 ** when the optimization is enabled. Providing the ability to
1679 ** disable the optimization allows the older, buggy application code to work
1680 ** without change even with newer versions of SQLite.
1681 **
1682 ** [[SQLITE_CONFIG_PCACHE]] [[SQLITE_CONFIG_GETPCACHE]]
1683 ** <dt>SQLITE_CONFIG_PCACHE and SQLITE_CONFIG_GETPCACHE
1684 ** <dd> These options are obsolete and should not be used by new code.
1685 ** They are retained for backwards compatibility but are now no-ops.
1686 ** </dd>
1687 **
1688 ** [[SQLITE_CONFIG_SQLLOG]]
1689 ** <dt>SQLITE_CONFIG_SQLLOG
1690 ** <dd>This option is only available if sqlite is compiled with the
1691 ** [SQLITE_ENABLE_SQLLOG] pre-processor macro defined. The first argument should
1692 ** be a pointer to a function of type void(*)(void*,sqlite3*,const char*, int).
1693 ** The second should be of type (void*). The callback is invoked by the library
1694 ** in three separate circumstances, identified by the value passed as the
1695 ** fourth parameter. If the fourth parameter is 0, then the database connection
1696 ** passed as the second argument has just been opened. The third argument
1697 ** points to a buffer containing the name of the main database file. If the
1698 ** fourth parameter is 1, then the SQL statement that the third parameter
1699 ** points to has just been executed. Or, if the fourth parameter is 2, then
1700 ** the connection being passed as the second parameter is being closed. The
1701 ** third parameter is passed NULL In this case. An example of using this
1702 ** configuration option can be seen in the "test_sqllog.c" source file in
1703 ** the canonical SQLite source tree.</dd>
1704 **
1705 ** [[SQLITE_CONFIG_MMAP_SIZE]]
1706 ** <dt>SQLITE_CONFIG_MMAP_SIZE
1707 ** <dd>^SQLITE_CONFIG_MMAP_SIZE takes two 64-bit integer (sqlite3_int64) values
1708 ** that are the default mmap size limit (the default setting for
1709 ** [PRAGMA mmap_size]) and the maximum allowed mmap size limit.
1710 ** ^The default setting can be overridden by each database connection using
1711 ** either the [PRAGMA mmap_size] command, or by using the
1712 ** [SQLITE_FCNTL_MMAP_SIZE] file control. ^(The maximum allowed mmap size
1713 ** cannot be changed at run-time. Nor may the maximum allowed mmap size
1714 ** exceed the compile-time maximum mmap size set by the
1715 ** [SQLITE_MAX_MMAP_SIZE] compile-time option.)^
1716 ** ^If either argument to this option is negative, then that argument is
1717 ** changed to its compile-time default.
1718 **
1719 ** [[SQLITE_CONFIG_WIN32_HEAPSIZE]]
1720 ** <dt>SQLITE_CONFIG_WIN32_HEAPSIZE
1721 ** <dd>^This option is only available if SQLite is compiled for Windows
1722 ** with the [SQLITE_WIN32_MALLOC] pre-processor macro defined.
1723 ** SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value
1724 ** that specifies the maximum size of the created heap.
1725 ** </dl>
1726 */
1727 #define SQLITE_CONFIG_SINGLETHREAD 1 /* nil */
1728 #define SQLITE_CONFIG_MULTITHREAD 2 /* nil */
1729 #define SQLITE_CONFIG_SERIALIZED 3 /* nil */
1730 #define SQLITE_CONFIG_MALLOC 4 /* sqlite3_mem_methods* */
1731 #define SQLITE_CONFIG_GETMALLOC 5 /* sqlite3_mem_methods* */
1732 #define SQLITE_CONFIG_SCRATCH 6 /* void*, int sz, int N */
1733 #define SQLITE_CONFIG_PAGECACHE 7 /* void*, int sz, int N */
1734 #define SQLITE_CONFIG_HEAP 8 /* void*, int nByte, int min */
1735 #define SQLITE_CONFIG_MEMSTATUS 9 /* boolean */
1736 #define SQLITE_CONFIG_MUTEX 10 /* sqlite3_mutex_methods* */
1737 #define SQLITE_CONFIG_GETMUTEX 11 /* sqlite3_mutex_methods* */
1738 /* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */
1739 #define SQLITE_CONFIG_LOOKASIDE 13 /* int int */
1740 #define SQLITE_CONFIG_PCACHE 14 /* no-op */
1741 #define SQLITE_CONFIG_GETPCACHE 15 /* no-op */
1742 #define SQLITE_CONFIG_LOG 16 /* xFunc, void* */
1743 #define SQLITE_CONFIG_URI 17 /* int */
1744 #define SQLITE_CONFIG_PCACHE2 18 /* sqlite3_pcache_methods2* */
1745 #define SQLITE_CONFIG_GETPCACHE2 19 /* sqlite3_pcache_methods2* */
1746 #define SQLITE_CONFIG_COVERING_INDEX_SCAN 20 /* int */
1747 #define SQLITE_CONFIG_SQLLOG 21 /* xSqllog, void* */
1748 #define SQLITE_CONFIG_MMAP_SIZE 22 /* sqlite3_int64, sqlite3_int64 */
1749 #define SQLITE_CONFIG_WIN32_HEAPSIZE 23 /* int nByte */
1750 
1751 /*
1752 ** CAPI3REF: Database Connection Configuration Options
1753 **
1754 ** These constants are the available integer configuration options that
1755 ** can be passed as the second argument to the [sqlite3_db_config()] interface.
1756 **
1757 ** New configuration options may be added in future releases of SQLite.
1758 ** Existing configuration options might be discontinued. Applications
1759 ** should check the return code from [sqlite3_db_config()] to make sure that
1760 ** the call worked. ^The [sqlite3_db_config()] interface will return a
1761 ** non-zero [error code] if a discontinued or unsupported configuration option
1762 ** is invoked.
1763 **
1764 ** <dl>
1765 ** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
1766 ** <dd> ^This option takes three additional arguments that determine the
1767 ** [lookaside memory allocator] configuration for the [database connection].
1768 ** ^The first argument (the third parameter to [sqlite3_db_config()] is a
1769 ** pointer to a memory buffer to use for lookaside memory.
1770 ** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
1771 ** may be NULL in which case SQLite will allocate the
1772 ** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
1773 ** size of each lookaside buffer slot. ^The third argument is the number of
1774 ** slots. The size of the buffer in the first argument must be greater than
1775 ** or equal to the product of the second and third arguments. The buffer
1776 ** must be aligned to an 8-byte boundary. ^If the second argument to
1777 ** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally
1778 ** rounded down to the next smaller multiple of 8. ^(The lookaside memory
1779 ** configuration for a database connection can only be changed when that
1780 ** connection is not currently using lookaside memory, or in other words
1781 ** when the "current value" returned by
1782 ** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
1783 ** Any attempt to change the lookaside memory configuration when lookaside
1784 ** memory is in use leaves the configuration unchanged and returns
1785 ** [SQLITE_BUSY].)^</dd>
1786 **
1787 ** <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>
1788 ** <dd> ^This option is used to enable or disable the enforcement of
1789 ** [foreign key constraints]. There should be two additional arguments.
1790 ** The first argument is an integer which is 0 to disable FK enforcement,
1791 ** positive to enable FK enforcement or negative to leave FK enforcement
1792 ** unchanged. The second parameter is a pointer to an integer into which
1793 ** is written 0 or 1 to indicate whether FK enforcement is off or on
1794 ** following this call. The second parameter may be a NULL pointer, in
1795 ** which case the FK enforcement setting is not reported back. </dd>
1796 **
1797 ** <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>
1798 ** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
1799 ** There should be two additional arguments.
1800 ** The first argument is an integer which is 0 to disable triggers,
1801 ** positive to enable triggers or negative to leave the setting unchanged.
1802 ** The second parameter is a pointer to an integer into which
1803 ** is written 0 or 1 to indicate whether triggers are disabled or enabled
1804 ** following this call. The second parameter may be a NULL pointer, in
1805 ** which case the trigger setting is not reported back. </dd>
1806 **
1807 ** </dl>
1808 */
1809 #define SQLITE_DBCONFIG_LOOKASIDE 1001 /* void* int int */
1810 #define SQLITE_DBCONFIG_ENABLE_FKEY 1002 /* int int* */
1811 #define SQLITE_DBCONFIG_ENABLE_TRIGGER 1003 /* int int* */
1812 
1813 
1814 /*
1815 ** CAPI3REF: Enable Or Disable Extended Result Codes
1816 **
1817 ** ^The sqlite3_extended_result_codes() routine enables or disables the
1818 ** [extended result codes] feature of SQLite. ^The extended result
1819 ** codes are disabled by default for historical compatibility.
1820 */
1822 
1823 /*
1824 ** CAPI3REF: Last Insert Rowid
1825 **
1826 ** ^Each entry in most SQLite tables (except for [WITHOUT ROWID] tables)
1827 ** has a unique 64-bit signed
1828 ** integer key called the [ROWID | "rowid"]. ^The rowid is always available
1829 ** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
1830 ** names are not also used by explicitly declared columns. ^If
1831 ** the table has a column of type [INTEGER PRIMARY KEY] then that column
1832 ** is another alias for the rowid.
1833 **
1834 ** ^The sqlite3_last_insert_rowid(D) interface returns the [rowid] of the
1835 ** most recent successful [INSERT] into a rowid table or [virtual table]
1836 ** on database connection D.
1837 ** ^Inserts into [WITHOUT ROWID] tables are not recorded.
1838 ** ^If no successful [INSERT]s into rowid tables
1839 ** have ever occurred on the database connection D,
1840 ** then sqlite3_last_insert_rowid(D) returns zero.
1841 **
1842 ** ^(If an [INSERT] occurs within a trigger or within a [virtual table]
1843 ** method, then this routine will return the [rowid] of the inserted
1844 ** row as long as the trigger or virtual table method is running.
1845 ** But once the trigger or virtual table method ends, the value returned
1846 ** by this routine reverts to what it was before the trigger or virtual
1847 ** table method began.)^
1848 **
1849 ** ^An [INSERT] that fails due to a constraint violation is not a
1850 ** successful [INSERT] and does not change the value returned by this
1851 ** routine. ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
1852 ** and INSERT OR ABORT make no changes to the return value of this
1853 ** routine when their insertion fails. ^(When INSERT OR REPLACE
1854 ** encounters a constraint violation, it does not fail. The
1855 ** INSERT continues to completion after deleting rows that caused
1856 ** the constraint problem so INSERT OR REPLACE will always change
1857 ** the return value of this interface.)^
1858 **
1859 ** ^For the purposes of this routine, an [INSERT] is considered to
1860 ** be successful even if it is subsequently rolled back.
1861 **
1862 ** This function is accessible to SQL statements via the
1863 ** [last_insert_rowid() SQL function].
1864 **
1865 ** If a separate thread performs a new [INSERT] on the same
1866 ** database connection while the [sqlite3_last_insert_rowid()]
1867 ** function is running and thus changes the last insert [rowid],
1868 ** then the value returned by [sqlite3_last_insert_rowid()] is
1869 ** unpredictable and might not equal either the old or the new
1870 ** last insert [rowid].
1871 */
1873 
1874 /*
1875 ** CAPI3REF: Count The Number Of Rows Modified
1876 **
1877 ** ^This function returns the number of database rows that were changed
1878 ** or inserted or deleted by the most recently completed SQL statement
1879 ** on the [database connection] specified by the first parameter.
1880 ** ^(Only changes that are directly specified by the [INSERT], [UPDATE],
1881 ** or [DELETE] statement are counted. Auxiliary changes caused by
1882 ** triggers or [foreign key actions] are not counted.)^ Use the
1883 ** [sqlite3_total_changes()] function to find the total number of changes
1884 ** including changes caused by triggers and foreign key actions.
1885 **
1886 ** ^Changes to a view that are simulated by an [INSTEAD OF trigger]
1887 ** are not counted. Only real table changes are counted.
1888 **
1889 ** ^(A "row change" is a change to a single row of a single table
1890 ** caused by an INSERT, DELETE, or UPDATE statement. Rows that
1891 ** are changed as side effects of [REPLACE] constraint resolution,
1892 ** rollback, ABORT processing, [DROP TABLE], or by any other
1893 ** mechanisms do not count as direct row changes.)^
1894 **
1895 ** A "trigger context" is a scope of execution that begins and
1896 ** ends with the script of a [CREATE TRIGGER | trigger].
1897 ** Most SQL statements are
1898 ** evaluated outside of any trigger. This is the "top level"
1899 ** trigger context. If a trigger fires from the top level, a
1900 ** new trigger context is entered for the duration of that one
1901 ** trigger. Subtriggers create subcontexts for their duration.
1902 **
1903 ** ^Calling [sqlite3_exec()] or [sqlite3_step()] recursively does
1904 ** not create a new trigger context.
1905 **
1906 ** ^This function returns the number of direct row changes in the
1907 ** most recent INSERT, UPDATE, or DELETE statement within the same
1908 ** trigger context.
1909 **
1910 ** ^Thus, when called from the top level, this function returns the
1911 ** number of changes in the most recent INSERT, UPDATE, or DELETE
1912 ** that also occurred at the top level. ^(Within the body of a trigger,
1913 ** the sqlite3_changes() interface can be called to find the number of
1914 ** changes in the most recently completed INSERT, UPDATE, or DELETE
1915 ** statement within the body of the same trigger.
1916 ** However, the number returned does not include changes
1917 ** caused by subtriggers since those have their own context.)^
1918 **
1919 ** See also the [sqlite3_total_changes()] interface, the
1920 ** [count_changes pragma], and the [changes() SQL function].
1921 **
1922 ** If a separate thread makes changes on the same database connection
1923 ** while [sqlite3_changes()] is running then the value returned
1924 ** is unpredictable and not meaningful.
1925 */
1927 
1928 /*
1929 ** CAPI3REF: Total Number Of Rows Modified
1930 **
1931 ** ^This function returns the number of row changes caused by [INSERT],
1932 ** [UPDATE] or [DELETE] statements since the [database connection] was opened.
1933 ** ^(The count returned by sqlite3_total_changes() includes all changes
1934 ** from all [CREATE TRIGGER | trigger] contexts and changes made by
1935 ** [foreign key actions]. However,
1936 ** the count does not include changes used to implement [REPLACE] constraints,
1937 ** do rollbacks or ABORT processing, or [DROP TABLE] processing. The
1938 ** count does not include rows of views that fire an [INSTEAD OF trigger],
1939 ** though if the INSTEAD OF trigger makes changes of its own, those changes
1940 ** are counted.)^
1941 ** ^The sqlite3_total_changes() function counts the changes as soon as
1942 ** the statement that makes them is completed (when the statement handle
1943 ** is passed to [sqlite3_reset()] or [sqlite3_finalize()]).
1944 **
1945 ** See also the [sqlite3_changes()] interface, the
1946 ** [count_changes pragma], and the [total_changes() SQL function].
1947 **
1948 ** If a separate thread makes changes on the same database connection
1949 ** while [sqlite3_total_changes()] is running then the value
1950 ** returned is unpredictable and not meaningful.
1951 */
1953 
1954 /*
1955 ** CAPI3REF: Interrupt A Long-Running Query
1956 **
1957 ** ^This function causes any pending database operation to abort and
1958 ** return at its earliest opportunity. This routine is typically
1959 ** called in response to a user action such as pressing "Cancel"
1960 ** or Ctrl-C where the user wants a long query operation to halt
1961 ** immediately.
1962 **
1963 ** ^It is safe to call this routine from a thread different from the
1964 ** thread that is currently running the database operation. But it
1965 ** is not safe to call this routine with a [database connection] that
1966 ** is closed or might close before sqlite3_interrupt() returns.
1967 **
1968 ** ^If an SQL operation is very nearly finished at the time when
1969 ** sqlite3_interrupt() is called, then it might not have an opportunity
1970 ** to be interrupted and might continue to completion.
1971 **
1972 ** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
1973 ** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
1974 ** that is inside an explicit transaction, then the entire transaction
1975 ** will be rolled back automatically.
1976 **
1977 ** ^The sqlite3_interrupt(D) call is in effect until all currently running
1978 ** SQL statements on [database connection] D complete. ^Any new SQL statements
1979 ** that are started after the sqlite3_interrupt() call and before the
1980 ** running statements reaches zero are interrupted as if they had been
1981 ** running prior to the sqlite3_interrupt() call. ^New SQL statements
1982 ** that are started after the running statement count reaches zero are
1983 ** not effected by the sqlite3_interrupt().
1984 ** ^A call to sqlite3_interrupt(D) that occurs when there are no running
1985 ** SQL statements is a no-op and has no effect on SQL statements
1986 ** that are started after the sqlite3_interrupt() call returns.
1987 **
1988 ** If the database connection closes while [sqlite3_interrupt()]
1989 ** is running then bad things will likely happen.
1990 */
1992 
1993 /*
1994 ** CAPI3REF: Determine If An SQL Statement Is Complete
1995 **
1996 ** These routines are useful during command-line input to determine if the
1997 ** currently entered text seems to form a complete SQL statement or
1998 ** if additional input is needed before sending the text into
1999 ** SQLite for parsing. ^These routines return 1 if the input string
2000 ** appears to be a complete SQL statement. ^A statement is judged to be
2001 ** complete if it ends with a semicolon token and is not a prefix of a
2002 ** well-formed CREATE TRIGGER statement. ^Semicolons that are embedded within
2003 ** string literals or quoted identifier names or comments are not
2004 ** independent tokens (they are part of the token in which they are
2005 ** embedded) and thus do not count as a statement terminator. ^Whitespace
2006 ** and comments that follow the final semicolon are ignored.
2007 **
2008 ** ^These routines return 0 if the statement is incomplete. ^If a
2009 ** memory allocation fails, then SQLITE_NOMEM is returned.
2010 **
2011 ** ^These routines do not parse the SQL statements thus
2012 ** will not detect syntactically incorrect SQL.
2013 **
2014 ** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior
2015 ** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked
2016 ** automatically by sqlite3_complete16(). If that initialization fails,
2017 ** then the return value from sqlite3_complete16() will be non-zero
2018 ** regardless of whether or not the input SQL is complete.)^
2019 **
2020 ** The input to [sqlite3_complete()] must be a zero-terminated
2021 ** UTF-8 string.
2022 **
2023 ** The input to [sqlite3_complete16()] must be a zero-terminated
2024 ** UTF-16 string in native byte order.
2025 */
2026 SQLITE_API int sqlite3_complete(const char *sql);
2027 SQLITE_API int sqlite3_complete16(const void *sql);
2028 
2029 /*
2030 ** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
2031 **
2032 ** ^This routine sets a callback function that might be invoked whenever
2033 ** an attempt is made to open a database table that another thread
2034 ** or process has locked.
2035 **
2036 ** ^If the busy callback is NULL, then [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED]
2037 ** is returned immediately upon encountering the lock. ^If the busy callback
2038 ** is not NULL, then the callback might be invoked with two arguments.
2039 **
2040 ** ^The first argument to the busy handler is a copy of the void* pointer which
2041 ** is the third argument to sqlite3_busy_handler(). ^The second argument to
2042 ** the busy handler callback is the number of times that the busy handler has
2043 ** been invoked for this locking event. ^If the
2044 ** busy callback returns 0, then no additional attempts are made to
2045 ** access the database and [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED] is returned.
2046 ** ^If the callback returns non-zero, then another attempt
2047 ** is made to open the database for reading and the cycle repeats.
2048 **
2049 ** The presence of a busy handler does not guarantee that it will be invoked
2050 ** when there is lock contention. ^If SQLite determines that invoking the busy
2051 ** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
2052 ** or [SQLITE_IOERR_BLOCKED] instead of invoking the busy handler.
2053 ** Consider a scenario where one process is holding a read lock that
2054 ** it is trying to promote to a reserved lock and
2055 ** a second process is holding a reserved lock that it is trying
2056 ** to promote to an exclusive lock. The first process cannot proceed
2057 ** because it is blocked by the second and the second process cannot
2058 ** proceed because it is blocked by the first. If both processes
2059 ** invoke the busy handlers, neither will make any progress. Therefore,
2060 ** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
2061 ** will induce the first process to release its read lock and allow
2062 ** the second process to proceed.
2063 **
2064 ** ^The default busy callback is NULL.
2065 **
2066 ** ^The [SQLITE_BUSY] error is converted to [SQLITE_IOERR_BLOCKED]
2067 ** when SQLite is in the middle of a large transaction where all the
2068 ** changes will not fit into the in-memory cache. SQLite will
2069 ** already hold a RESERVED lock on the database file, but it needs
2070 ** to promote this lock to EXCLUSIVE so that it can spill cache
2071 ** pages into the database file without harm to concurrent
2072 ** readers. ^If it is unable to promote the lock, then the in-memory
2073 ** cache will be left in an inconsistent state and so the error
2074 ** code is promoted from the relatively benign [SQLITE_BUSY] to
2075 ** the more severe [SQLITE_IOERR_BLOCKED]. ^This error code promotion
2076 ** forces an automatic rollback of the changes. See the
2077 ** <a href="/cvstrac/wiki?p=CorruptionFollowingBusyError">
2078 ** CorruptionFollowingBusyError</a> wiki page for a discussion of why
2079 ** this is important.
2080 **
2081 ** ^(There can only be a single busy handler defined for each
2082 ** [database connection]. Setting a new busy handler clears any
2083 ** previously set handler.)^ ^Note that calling [sqlite3_busy_timeout()]
2084 ** will also set or clear the busy handler.
2085 **
2086 ** The busy callback should not take any actions which modify the
2087 ** database connection that invoked the busy handler. Any such actions
2088 ** result in undefined behavior.
2089 **
2090 ** A busy handler must not close the database connection
2091 ** or [prepared statement] that invoked the busy handler.
2092 */
2093 SQLITE_API int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);
2094 
2095 /*
2096 ** CAPI3REF: Set A Busy Timeout
2097 **
2098 ** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
2099 ** for a specified amount of time when a table is locked. ^The handler
2100 ** will sleep multiple times until at least "ms" milliseconds of sleeping
2101 ** have accumulated. ^After at least "ms" milliseconds of sleeping,
2102 ** the handler returns 0 which causes [sqlite3_step()] to return
2103 ** [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED].
2104 **
2105 ** ^Calling this routine with an argument less than or equal to zero
2106 ** turns off all busy handlers.
2107 **
2108 ** ^(There can only be a single busy handler for a particular
2109 ** [database connection] any any given moment. If another busy handler
2110 ** was defined (using [sqlite3_busy_handler()]) prior to calling
2111 ** this routine, that other busy handler is cleared.)^
2112 */
2114 
2115 /*
2116 ** CAPI3REF: Convenience Routines For Running Queries
2117 **
2118 ** This is a legacy interface that is preserved for backwards compatibility.
2119 ** Use of this interface is not recommended.
2120 **
2121 ** Definition: A <b>result table</b> is memory data structure created by the
2122 ** [sqlite3_get_table()] interface. A result table records the
2123 ** complete query results from one or more queries.
2124 **
2125 ** The table conceptually has a number of rows and columns. But
2126 ** these numbers are not part of the result table itself. These
2127 ** numbers are obtained separately. Let N be the number of rows
2128 ** and M be the number of columns.
2129 **
2130 ** A result table is an array of pointers to zero-terminated UTF-8 strings.
2131 ** There are (N+1)*M elements in the array. The first M pointers point
2132 ** to zero-terminated strings that contain the names of the columns.
2133 ** The remaining entries all point to query results. NULL values result
2134 ** in NULL pointers. All other values are in their UTF-8 zero-terminated
2135 ** string representation as returned by [sqlite3_column_text()].
2136 **
2137 ** A result table might consist of one or more memory allocations.
2138 ** It is not safe to pass a result table directly to [sqlite3_free()].
2139 ** A result table should be deallocated using [sqlite3_free_table()].
2140 **
2141 ** ^(As an example of the result table format, suppose a query result
2142 ** is as follows:
2143 **
2144 ** <blockquote><pre>
2145 ** Name | Age
2146 ** -----------------------
2147 ** Alice | 43
2148 ** Bob | 28
2149 ** Cindy | 21
2150 ** </pre></blockquote>
2151 **
2152 ** There are two column (M==2) and three rows (N==3). Thus the
2153 ** result table has 8 entries. Suppose the result table is stored
2154 ** in an array names azResult. Then azResult holds this content:
2155 **
2156 ** <blockquote><pre>
2157 ** azResult&#91;0] = "Name";
2158 ** azResult&#91;1] = "Age";
2159 ** azResult&#91;2] = "Alice";
2160 ** azResult&#91;3] = "43";
2161 ** azResult&#91;4] = "Bob";
2162 ** azResult&#91;5] = "28";
2163 ** azResult&#91;6] = "Cindy";
2164 ** azResult&#91;7] = "21";
2165 ** </pre></blockquote>)^
2166 **
2167 ** ^The sqlite3_get_table() function evaluates one or more
2168 ** semicolon-separated SQL statements in the zero-terminated UTF-8
2169 ** string of its 2nd parameter and returns a result table to the
2170 ** pointer given in its 3rd parameter.
2171 **
2172 ** After the application has finished with the result from sqlite3_get_table(),
2173 ** it must pass the result table pointer to sqlite3_free_table() in order to
2174 ** release the memory that was malloced. Because of the way the
2175 ** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
2176 ** function must not try to call [sqlite3_free()] directly. Only
2177 ** [sqlite3_free_table()] is able to release the memory properly and safely.
2178 **
2179 ** The sqlite3_get_table() interface is implemented as a wrapper around
2180 ** [sqlite3_exec()]. The sqlite3_get_table() routine does not have access
2181 ** to any internal data structures of SQLite. It uses only the public
2182 ** interface defined here. As a consequence, errors that occur in the
2183 ** wrapper layer outside of the internal [sqlite3_exec()] call are not
2184 ** reflected in subsequent calls to [sqlite3_errcode()] or
2185 ** [sqlite3_errmsg()].
2186 */
2188  sqlite3 *db, /* An open database */
2189  const char *zSql, /* SQL to be evaluated */
2190  char ***pazResult, /* Results of the query */
2191  int *pnRow, /* Number of result rows written here */
2192  int *pnColumn, /* Number of result columns written here */
2193  char **pzErrmsg /* Error msg written here */
2194 );
2195 SQLITE_API void sqlite3_free_table(char **result);
2196 
2197 /*
2198 ** CAPI3REF: Formatted String Printing Functions
2199 **
2200 ** These routines are work-alikes of the "printf()" family of functions
2201 ** from the standard C library.
2202 **
2203 ** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
2204 ** results into memory obtained from [sqlite3_malloc()].
2205 ** The strings returned by these two routines should be
2206 ** released by [sqlite3_free()]. ^Both routines return a
2207 ** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
2208 ** memory to hold the resulting string.
2209 **
2210 ** ^(The sqlite3_snprintf() routine is similar to "snprintf()" from
2211 ** the standard C library. The result is written into the
2212 ** buffer supplied as the second parameter whose size is given by
2213 ** the first parameter. Note that the order of the
2214 ** first two parameters is reversed from snprintf().)^ This is an
2215 ** historical accident that cannot be fixed without breaking
2216 ** backwards compatibility. ^(Note also that sqlite3_snprintf()
2217 ** returns a pointer to its buffer instead of the number of
2218 ** characters actually written into the buffer.)^ We admit that
2219 ** the number of characters written would be a more useful return
2220 ** value but we cannot change the implementation of sqlite3_snprintf()
2221 ** now without breaking compatibility.
2222 **
2223 ** ^As long as the buffer size is greater than zero, sqlite3_snprintf()
2224 ** guarantees that the buffer is always zero-terminated. ^The first
2225 ** parameter "n" is the total size of the buffer, including space for
2226 ** the zero terminator. So the longest string that can be completely
2227 ** written will be n-1 characters.
2228 **
2229 ** ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf().
2230 **
2231 ** These routines all implement some additional formatting
2232 ** options that are useful for constructing SQL statements.
2233 ** All of the usual printf() formatting options apply. In addition, there
2234 ** is are "%q", "%Q", and "%z" options.
2235 **
2236 ** ^(The %q option works like %s in that it substitutes a nul-terminated
2237 ** string from the argument list. But %q also doubles every '\'' character.
2238 ** %q is designed for use inside a string literal.)^ By doubling each '\''
2239 ** character it escapes that character and allows it to be inserted into
2240 ** the string.
2241 **
2242 ** For example, assume the string variable zText contains text as follows:
2243 **
2244 ** <blockquote><pre>
2245 ** char *zText = "It's a happy day!";
2246 ** </pre></blockquote>
2247 **
2248 ** One can use this text in an SQL statement as follows:
2249 **
2250 ** <blockquote><pre>
2251 ** char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);
2252 ** sqlite3_exec(db, zSQL, 0, 0, 0);
2253 ** sqlite3_free(zSQL);
2254 ** </pre></blockquote>
2255 **
2256 ** Because the %q format string is used, the '\'' character in zText
2257 ** is escaped and the SQL generated is as follows:
2258 **
2259 ** <blockquote><pre>
2260 ** INSERT INTO table1 VALUES('It''s a happy day!')
2261 ** </pre></blockquote>
2262 **
2263 ** This is correct. Had we used %s instead of %q, the generated SQL
2264 ** would have looked like this:
2265 **
2266 ** <blockquote><pre>
2267 ** INSERT INTO table1 VALUES('It's a happy day!');
2268 ** </pre></blockquote>
2269 **
2270 ** This second example is an SQL syntax error. As a general rule you should
2271 ** always use %q instead of %s when inserting text into a string literal.
2272 **
2273 ** ^(The %Q option works like %q except it also adds single quotes around
2274 ** the outside of the total string. Additionally, if the parameter in the
2275 ** argument list is a NULL pointer, %Q substitutes the text "NULL" (without
2276 ** single quotes).)^ So, for example, one could say:
2277 **
2278 ** <blockquote><pre>
2279 ** char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);
2280 ** sqlite3_exec(db, zSQL, 0, 0, 0);
2281 ** sqlite3_free(zSQL);
2282 ** </pre></blockquote>
2283 **
2284 ** The code above will render a correct SQL statement in the zSQL
2285 ** variable even if the zText variable is a NULL pointer.
2286 **
2287 ** ^(The "%z" formatting option works like "%s" but with the
2288 ** addition that after the string has been read and copied into
2289 ** the result, [sqlite3_free()] is called on the input string.)^
2290 */
2291 SQLITE_API char *sqlite3_mprintf(const char*,...);
2292 SQLITE_API char *sqlite3_vmprintf(const char*, va_list);
2293 SQLITE_API char *sqlite3_snprintf(int,char*,const char*, ...);
2294 SQLITE_API char *sqlite3_vsnprintf(int,char*,const char*, va_list);
2295 
2296 /*
2297 ** CAPI3REF: Memory Allocation Subsystem
2298 **
2299 ** The SQLite core uses these three routines for all of its own
2300 ** internal memory allocation needs. "Core" in the previous sentence
2301 ** does not include operating-system specific VFS implementation. The
2302 ** Windows VFS uses native malloc() and free() for some operations.
2303 **
2304 ** ^The sqlite3_malloc() routine returns a pointer to a block
2305 ** of memory at least N bytes in length, where N is the parameter.
2306 ** ^If sqlite3_malloc() is unable to obtain sufficient free
2307 ** memory, it returns a NULL pointer. ^If the parameter N to
2308 ** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
2309 ** a NULL pointer.
2310 **
2311 ** ^Calling sqlite3_free() with a pointer previously returned
2312 ** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
2313 ** that it might be reused. ^The sqlite3_free() routine is
2314 ** a no-op if is called with a NULL pointer. Passing a NULL pointer
2315 ** to sqlite3_free() is harmless. After being freed, memory
2316 ** should neither be read nor written. Even reading previously freed
2317 ** memory might result in a segmentation fault or other severe error.
2318 ** Memory corruption, a segmentation fault, or other severe error
2319 ** might result if sqlite3_free() is called with a non-NULL pointer that
2320 ** was not obtained from sqlite3_malloc() or sqlite3_realloc().
2321 **
2322 ** ^(The sqlite3_realloc() interface attempts to resize a
2323 ** prior memory allocation to be at least N bytes, where N is the
2324 ** second parameter. The memory allocation to be resized is the first
2325 ** parameter.)^ ^ If the first parameter to sqlite3_realloc()
2326 ** is a NULL pointer then its behavior is identical to calling
2327 ** sqlite3_malloc(N) where N is the second parameter to sqlite3_realloc().
2328 ** ^If the second parameter to sqlite3_realloc() is zero or
2329 ** negative then the behavior is exactly the same as calling
2330 ** sqlite3_free(P) where P is the first parameter to sqlite3_realloc().
2331 ** ^sqlite3_realloc() returns a pointer to a memory allocation
2332 ** of at least N bytes in size or NULL if sufficient memory is unavailable.
2333 ** ^If M is the size of the prior allocation, then min(N,M) bytes
2334 ** of the prior allocation are copied into the beginning of buffer returned
2335 ** by sqlite3_realloc() and the prior allocation is freed.
2336 ** ^If sqlite3_realloc() returns NULL, then the prior allocation
2337 ** is not freed.
2338 **
2339 ** ^The memory returned by sqlite3_malloc() and sqlite3_realloc()
2340 ** is always aligned to at least an 8 byte boundary, or to a
2341 ** 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time
2342 ** option is used.
2343 **
2344 ** In SQLite version 3.5.0 and 3.5.1, it was possible to define
2345 ** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
2346 ** implementation of these routines to be omitted. That capability
2347 ** is no longer provided. Only built-in memory allocators can be used.
2348 **
2349 ** Prior to SQLite version 3.7.10, the Windows OS interface layer called
2350 ** the system malloc() and free() directly when converting
2351 ** filenames between the UTF-8 encoding used by SQLite
2352 ** and whatever filename encoding is used by the particular Windows
2353 ** installation. Memory allocation errors were detected, but
2354 ** they were reported back as [SQLITE_CANTOPEN] or
2355 ** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
2356 **
2357 ** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
2358 ** must be either NULL or else pointers obtained from a prior
2359 ** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
2360 ** not yet been released.
2361 **
2362 ** The application must not read or write any part of
2363 ** a block of memory after it has been released using
2364 ** [sqlite3_free()] or [sqlite3_realloc()].
2365 */
2366 SQLITE_API void *sqlite3_malloc(int);
2367 SQLITE_API void *sqlite3_realloc(void*, int);
2368 SQLITE_API void sqlite3_free(void*);
2369 
2370 /*
2371 ** CAPI3REF: Memory Allocator Statistics
2372 **
2373 ** SQLite provides these two interfaces for reporting on the status
2374 ** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
2375 ** routines, which form the built-in memory allocation subsystem.
2376 **
2377 ** ^The [sqlite3_memory_used()] routine returns the number of bytes
2378 ** of memory currently outstanding (malloced but not freed).
2379 ** ^The [sqlite3_memory_highwater()] routine returns the maximum
2380 ** value of [sqlite3_memory_used()] since the high-water mark
2381 ** was last reset. ^The values returned by [sqlite3_memory_used()] and
2382 ** [sqlite3_memory_highwater()] include any overhead
2383 ** added by SQLite in its implementation of [sqlite3_malloc()],
2384 ** but not overhead added by the any underlying system library
2385 ** routines that [sqlite3_malloc()] may call.
2386 **
2387 ** ^The memory high-water mark is reset to the current value of
2388 ** [sqlite3_memory_used()] if and only if the parameter to
2389 ** [sqlite3_memory_highwater()] is true. ^The value returned
2390 ** by [sqlite3_memory_highwater(1)] is the high-water mark
2391 ** prior to the reset.
2392 */
2393 SQLITE_API sqlite3_int64 sqlite3_memory_used(void);
2394 SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag);
2395 
2396 /*
2397 ** CAPI3REF: Pseudo-Random Number Generator
2398 **
2399 ** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
2400 ** select random [ROWID | ROWIDs] when inserting new records into a table that
2401 ** already uses the largest possible [ROWID]. The PRNG is also used for
2402 ** the build-in random() and randomblob() SQL functions. This interface allows
2403 ** applications to access the same PRNG for other purposes.
2404 **
2405 ** ^A call to this routine stores N bytes of randomness into buffer P.
2406 **
2407 ** ^The first time this routine is invoked (either internally or by
2408 ** the application) the PRNG is seeded using randomness obtained
2409 ** from the xRandomness method of the default [sqlite3_vfs] object.
2410 ** ^On all subsequent invocations, the pseudo-randomness is generated
2411 ** internally and without recourse to the [sqlite3_vfs] xRandomness
2412 ** method.
2413 */
2414 SQLITE_API void sqlite3_randomness(int N, void *P);
2415 
2416 /*
2417 ** CAPI3REF: Compile-Time Authorization Callbacks
2418 **
2419 ** ^This routine registers an authorizer callback with a particular
2420 ** [database connection], supplied in the first argument.
2421 ** ^The authorizer callback is invoked as SQL statements are being compiled
2422 ** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
2423 ** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()]. ^At various
2424 ** points during the compilation process, as logic is being created
2425 ** to perform various actions, the authorizer callback is invoked to
2426 ** see if those actions are allowed. ^The authorizer callback should
2427 ** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
2428 ** specific action but allow the SQL statement to continue to be
2429 ** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
2430 ** rejected with an error. ^If the authorizer callback returns
2431 ** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
2432 ** then the [sqlite3_prepare_v2()] or equivalent call that triggered
2433 ** the authorizer will fail with an error message.
2434 **
2435 ** When the callback returns [SQLITE_OK], that means the operation
2436 ** requested is ok. ^When the callback returns [SQLITE_DENY], the
2437 ** [sqlite3_prepare_v2()] or equivalent call that triggered the
2438 ** authorizer will fail with an error message explaining that
2439 ** access is denied.
2440 **
2441 ** ^The first parameter to the authorizer callback is a copy of the third
2442 ** parameter to the sqlite3_set_authorizer() interface. ^The second parameter
2443 ** to the callback is an integer [SQLITE_COPY | action code] that specifies
2444 ** the particular action to be authorized. ^The third through sixth parameters
2445 ** to the callback are zero-terminated strings that contain additional
2446 ** details about the action to be authorized.
2447 **
2448 ** ^If the action code is [SQLITE_READ]
2449 ** and the callback returns [SQLITE_IGNORE] then the
2450 ** [prepared statement] statement is constructed to substitute
2451 ** a NULL value in place of the table column that would have
2452 ** been read if [SQLITE_OK] had been returned. The [SQLITE_IGNORE]
2453 ** return can be used to deny an untrusted user access to individual
2454 ** columns of a table.
2455 ** ^If the action code is [SQLITE_DELETE] and the callback returns
2456 ** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the
2457 ** [truncate optimization] is disabled and all rows are deleted individually.
2458 **
2459 ** An authorizer is used when [sqlite3_prepare | preparing]
2460 ** SQL statements from an untrusted source, to ensure that the SQL statements
2461 ** do not try to access data they are not allowed to see, or that they do not
2462 ** try to execute malicious statements that damage the database. For
2463 ** example, an application may allow a user to enter arbitrary
2464 ** SQL queries for evaluation by a database. But the application does
2465 ** not want the user to be able to make arbitrary changes to the
2466 ** database. An authorizer could then be put in place while the
2467 ** user-entered SQL is being [sqlite3_prepare | prepared] that
2468 ** disallows everything except [SELECT] statements.
2469 **
2470 ** Applications that need to process SQL from untrusted sources
2471 ** might also consider lowering resource limits using [sqlite3_limit()]
2472 ** and limiting database size using the [max_page_count] [PRAGMA]
2473 ** in addition to using an authorizer.
2474 **
2475 ** ^(Only a single authorizer can be in place on a database connection
2476 ** at a time. Each call to sqlite3_set_authorizer overrides the
2477 ** previous call.)^ ^Disable the authorizer by installing a NULL callback.
2478 ** The authorizer is disabled by default.
2479 **
2480 ** The authorizer callback must not do anything that will modify
2481 ** the database connection that invoked the authorizer callback.
2482 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
2483 ** database connections for the meaning of "modify" in this paragraph.
2484 **
2485 ** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the
2486 ** statement might be re-prepared during [sqlite3_step()] due to a
2487 ** schema change. Hence, the application should ensure that the
2488 ** correct authorizer callback remains in place during the [sqlite3_step()].
2489 **
2490 ** ^Note that the authorizer callback is invoked only during
2491 ** [sqlite3_prepare()] or its variants. Authorization is not
2492 ** performed during statement evaluation in [sqlite3_step()], unless
2493 ** as stated in the previous paragraph, sqlite3_step() invokes
2494 ** sqlite3_prepare_v2() to reprepare a statement after a schema change.
2495 */
2497  sqlite3*,
2498  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
2499  void *pUserData
2500 );
2501 
2502 /*
2503 ** CAPI3REF: Authorizer Return Codes
2504 **
2505 ** The [sqlite3_set_authorizer | authorizer callback function] must
2506 ** return either [SQLITE_OK] or one of these two constants in order
2507 ** to signal SQLite whether or not the action is permitted. See the
2508 ** [sqlite3_set_authorizer | authorizer documentation] for additional
2509 ** information.
2510 **
2511 ** Note that SQLITE_IGNORE is also used as a [SQLITE_ROLLBACK | return code]
2512 ** from the [sqlite3_vtab_on_conflict()] interface.
2513 */
2514 #define SQLITE_DENY 1 /* Abort the SQL statement with an error */
2515 #define SQLITE_IGNORE 2 /* Don't allow access, but don't generate an error */
2516 
2517 /*
2518 ** CAPI3REF: Authorizer Action Codes
2519 **
2520 ** The [sqlite3_set_authorizer()] interface registers a callback function
2521 ** that is invoked to authorize certain SQL statement actions. The
2522 ** second parameter to the callback is an integer code that specifies
2523 ** what action is being authorized. These are the integer action codes that
2524 ** the authorizer callback may be passed.
2525 **
2526 ** These action code values signify what kind of operation is to be
2527 ** authorized. The 3rd and 4th parameters to the authorization
2528 ** callback function will be parameters or NULL depending on which of these
2529 ** codes is used as the second parameter. ^(The 5th parameter to the
2530 ** authorizer callback is the name of the database ("main", "temp",
2531 ** etc.) if applicable.)^ ^The 6th parameter to the authorizer callback
2532 ** is the name of the inner-most trigger or view that is responsible for
2533 ** the access attempt or NULL if this access attempt is directly from
2534 ** top-level SQL code.
2535 */
2536 /******************************************* 3rd ************ 4th ***********/
2537 #define SQLITE_CREATE_INDEX 1 /* Index Name Table Name */
2538 #define SQLITE_CREATE_TABLE 2 /* Table Name NULL */
2539 #define SQLITE_CREATE_TEMP_INDEX 3 /* Index Name Table Name */
2540 #define SQLITE_CREATE_TEMP_TABLE 4 /* Table Name NULL */
2541 #define SQLITE_CREATE_TEMP_TRIGGER 5 /* Trigger Name Table Name */
2542 #define SQLITE_CREATE_TEMP_VIEW 6 /* View Name NULL */
2543 #define SQLITE_CREATE_TRIGGER 7 /* Trigger Name Table Name */
2544 #define SQLITE_CREATE_VIEW 8 /* View Name NULL */
2545 #define SQLITE_DELETE 9 /* Table Name NULL */
2546 #define SQLITE_DROP_INDEX 10 /* Index Name Table Name */
2547 #define SQLITE_DROP_TABLE 11 /* Table Name NULL */
2548 #define SQLITE_DROP_TEMP_INDEX 12 /* Index Name Table Name */
2549 #define SQLITE_DROP_TEMP_TABLE 13 /* Table Name NULL */
2550 #define SQLITE_DROP_TEMP_TRIGGER 14 /* Trigger Name Table Name */
2551 #define SQLITE_DROP_TEMP_VIEW 15 /* View Name NULL */
2552 #define SQLITE_DROP_TRIGGER 16 /* Trigger Name Table Name */
2553 #define SQLITE_DROP_VIEW 17 /* View Name NULL */
2554 #define SQLITE_INSERT 18 /* Table Name NULL */
2555 #define SQLITE_PRAGMA 19 /* Pragma Name 1st arg or NULL */
2556 #define SQLITE_READ 20 /* Table Name Column Name */
2557 #define SQLITE_SELECT 21 /* NULL NULL */
2558 #define SQLITE_TRANSACTION 22 /* Operation NULL */
2559 #define SQLITE_UPDATE 23 /* Table Name Column Name */
2560 #define SQLITE_ATTACH 24 /* Filename NULL */
2561 #define SQLITE_DETACH 25 /* Database Name NULL */
2562 #define SQLITE_ALTER_TABLE 26 /* Database Name Table Name */
2563 #define SQLITE_REINDEX 27 /* Index Name NULL */
2564 #define SQLITE_ANALYZE 28 /* Table Name NULL */
2565 #define SQLITE_CREATE_VTABLE 29 /* Table Name Module Name */
2566 #define SQLITE_DROP_VTABLE 30 /* Table Name Module Name */
2567 #define SQLITE_FUNCTION 31 /* NULL Function Name */
2568 #define SQLITE_SAVEPOINT 32 /* Operation Savepoint Name */
2569 #define SQLITE_COPY 0 /* No longer used */
2570 
2571 /*
2572 ** CAPI3REF: Tracing And Profiling Functions
2573 **
2574 ** These routines register callback functions that can be used for
2575 ** tracing and profiling the execution of SQL statements.
2576 **
2577 ** ^The callback function registered by sqlite3_trace() is invoked at
2578 ** various times when an SQL statement is being run by [sqlite3_step()].
2579 ** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
2580 ** SQL statement text as the statement first begins executing.
2581 ** ^(Additional sqlite3_trace() callbacks might occur
2582 ** as each triggered subprogram is entered. The callbacks for triggers
2583 ** contain a UTF-8 SQL comment that identifies the trigger.)^
2584 **
2585 ** The [SQLITE_TRACE_SIZE_LIMIT] compile-time option can be used to limit
2586 ** the length of [bound parameter] expansion in the output of sqlite3_trace().
2587 **
2588 ** ^The callback function registered by sqlite3_profile() is invoked
2589 ** as each SQL statement finishes. ^The profile callback contains
2590 ** the original statement text and an estimate of wall-clock time
2591 ** of how long that statement took to run. ^The profile callback
2592 ** time is in units of nanoseconds, however the current implementation
2593 ** is only capable of millisecond resolution so the six least significant
2594 ** digits in the time are meaningless. Future versions of SQLite
2595 ** might provide greater resolution on the profiler callback. The
2596 ** sqlite3_profile() function is considered experimental and is
2597 ** subject to change in future versions of SQLite.
2598 */
2599 SQLITE_API void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*);
2601  void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
2602 
2603 /*
2604 ** CAPI3REF: Query Progress Callbacks
2605 **
2606 ** ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback
2607 ** function X to be invoked periodically during long running calls to
2608 ** [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for
2609 ** database connection D. An example use for this
2610 ** interface is to keep a GUI updated during a large query.
2611 **
2612 ** ^The parameter P is passed through as the only parameter to the
2613 ** callback function X. ^The parameter N is the approximate number of
2614 ** [virtual machine instructions] that are evaluated between successive
2615 ** invocations of the callback X. ^If N is less than one then the progress
2616 ** handler is disabled.
2617 **
2618 ** ^Only a single progress handler may be defined at one time per
2619 ** [database connection]; setting a new progress handler cancels the
2620 ** old one. ^Setting parameter X to NULL disables the progress handler.
2621 ** ^The progress handler is also disabled by setting N to a value less
2622 ** than 1.
2623 **
2624 ** ^If the progress callback returns non-zero, the operation is
2625 ** interrupted. This feature can be used to implement a
2626 ** "Cancel" button on a GUI progress dialog box.
2627 **
2628 ** The progress handler callback must not do anything that will modify
2629 ** the database connection that invoked the progress handler.
2630 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
2631 ** database connections for the meaning of "modify" in this paragraph.
2632 **
2633 */
2634 SQLITE_API void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
2635 
2636 /*
2637 ** CAPI3REF: Opening A New Database Connection
2638 **
2639 ** ^These routines open an SQLite database file as specified by the
2640 ** filename argument. ^The filename argument is interpreted as UTF-8 for
2641 ** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
2642 ** order for sqlite3_open16(). ^(A [database connection] handle is usually
2643 ** returned in *ppDb, even if an error occurs. The only exception is that
2644 ** if SQLite is unable to allocate memory to hold the [sqlite3] object,
2645 ** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
2646 ** object.)^ ^(If the database is opened (and/or created) successfully, then
2647 ** [SQLITE_OK] is returned. Otherwise an [error code] is returned.)^ ^The
2648 ** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
2649 ** an English language description of the error following a failure of any
2650 ** of the sqlite3_open() routines.
2651 **
2652 ** ^The default encoding for the database will be UTF-8 if
2653 ** sqlite3_open() or sqlite3_open_v2() is called and
2654 ** UTF-16 in the native byte order if sqlite3_open16() is used.
2655 **
2656 ** Whether or not an error occurs when it is opened, resources
2657 ** associated with the [database connection] handle should be released by
2658 ** passing it to [sqlite3_close()] when it is no longer required.
2659 **
2660 ** The sqlite3_open_v2() interface works like sqlite3_open()
2661 ** except that it accepts two additional parameters for additional control
2662 ** over the new database connection. ^(The flags parameter to
2663 ** sqlite3_open_v2() can take one of
2664 ** the following three values, optionally combined with the
2665 ** [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE],
2666 ** [SQLITE_OPEN_PRIVATECACHE], and/or [SQLITE_OPEN_URI] flags:)^
2667 **
2668 ** <dl>
2669 ** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
2670 ** <dd>The database is opened in read-only mode. If the database does not
2671 ** already exist, an error is returned.</dd>)^
2672 **
2673 ** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
2674 ** <dd>The database is opened for reading and writing if possible, or reading
2675 ** only if the file is write protected by the operating system. In either
2676 ** case the database must already exist, otherwise an error is returned.</dd>)^
2677 **
2678 ** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
2679 ** <dd>The database is opened for reading and writing, and is created if
2680 ** it does not already exist. This is the behavior that is always used for
2681 ** sqlite3_open() and sqlite3_open16().</dd>)^
2682 ** </dl>
2683 **
2684 ** If the 3rd parameter to sqlite3_open_v2() is not one of the
2685 ** combinations shown above optionally combined with other
2686 ** [SQLITE_OPEN_READONLY | SQLITE_OPEN_* bits]
2687 ** then the behavior is undefined.
2688 **
2689 ** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
2690 ** opens in the multi-thread [threading mode] as long as the single-thread
2691 ** mode has not been set at compile-time or start-time. ^If the
2692 ** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
2693 ** in the serialized [threading mode] unless single-thread was
2694 ** previously selected at compile-time or start-time.
2695 ** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be
2696 ** eligible to use [shared cache mode], regardless of whether or not shared
2697 ** cache is enabled using [sqlite3_enable_shared_cache()]. ^The
2698 ** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not
2699 ** participate in [shared cache mode] even if it is enabled.
2700 **
2701 ** ^The fourth parameter to sqlite3_open_v2() is the name of the
2702 ** [sqlite3_vfs] object that defines the operating system interface that
2703 ** the new database connection should use. ^If the fourth parameter is
2704 ** a NULL pointer then the default [sqlite3_vfs] object is used.
2705 **
2706 ** ^If the filename is ":memory:", then a private, temporary in-memory database
2707 ** is created for the connection. ^This in-memory database will vanish when
2708 ** the database connection is closed. Future versions of SQLite might
2709 ** make use of additional special filenames that begin with the ":" character.
2710 ** It is recommended that when a database filename actually does begin with
2711 ** a ":" character you should prefix the filename with a pathname such as
2712 ** "./" to avoid ambiguity.
2713 **
2714 ** ^If the filename is an empty string, then a private, temporary
2715 ** on-disk database will be created. ^This private database will be
2716 ** automatically deleted as soon as the database connection is closed.
2717 **
2718 ** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
2719 **
2720 ** ^If [URI filename] interpretation is enabled, and the filename argument
2721 ** begins with "file:", then the filename is interpreted as a URI. ^URI
2722 ** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
2723 ** set in the fourth argument to sqlite3_open_v2(), or if it has
2724 ** been enabled globally using the [SQLITE_CONFIG_URI] option with the
2725 ** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
2726 ** As of SQLite version 3.7.7, URI filename interpretation is turned off
2727 ** by default, but future releases of SQLite might enable URI filename
2728 ** interpretation by default. See "[URI filenames]" for additional
2729 ** information.
2730 **
2731 ** URI filenames are parsed according to RFC 3986. ^If the URI contains an
2732 ** authority, then it must be either an empty string or the string
2733 ** "localhost". ^If the authority is not an empty string or "localhost", an
2734 ** error is returned to the caller. ^The fragment component of a URI, if
2735 ** present, is ignored.
2736 **
2737 ** ^SQLite uses the path component of the URI as the name of the disk file
2738 ** which contains the database. ^If the path begins with a '/' character,
2739 ** then it is interpreted as an absolute path. ^If the path does not begin
2740 ** with a '/' (meaning that the authority section is omitted from the URI)
2741 ** then the path is interpreted as a relative path.
2742 ** ^On windows, the first component of an absolute path
2743 ** is a drive specification (e.g. "C:").
2744 **
2745 ** [[core URI query parameters]]
2746 ** The query component of a URI may contain parameters that are interpreted
2747 ** either by SQLite itself, or by a [VFS | custom VFS implementation].
2748 ** SQLite interprets the following three query parameters:
2749 **
2750 ** <ul>
2751 ** <li> <b>vfs</b>: ^The "vfs" parameter may be used to specify the name of
2752 ** a VFS object that provides the operating system interface that should
2753 ** be used to access the database file on disk. ^If this option is set to
2754 ** an empty string the default VFS object is used. ^Specifying an unknown
2755 ** VFS is an error. ^If sqlite3_open_v2() is used and the vfs option is
2756 ** present, then the VFS specified by the option takes precedence over
2757 ** the value passed as the fourth parameter to sqlite3_open_v2().
2758 **
2759 ** <li> <b>mode</b>: ^(The mode parameter may be set to either "ro", "rw",
2760 ** "rwc", or "memory". Attempting to set it to any other value is
2761 ** an error)^.
2762 ** ^If "ro" is specified, then the database is opened for read-only
2763 ** access, just as if the [SQLITE_OPEN_READONLY] flag had been set in the
2764 ** third argument to sqlite3_open_v2(). ^If the mode option is set to
2765 ** "rw", then the database is opened for read-write (but not create)
2766 ** access, as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had
2767 ** been set. ^Value "rwc" is equivalent to setting both
2768 ** SQLITE_OPEN_READWRITE and SQLITE_OPEN_CREATE. ^If the mode option is
2769 ** set to "memory" then a pure [in-memory database] that never reads
2770 ** or writes from disk is used. ^It is an error to specify a value for
2771 ** the mode parameter that is less restrictive than that specified by
2772 ** the flags passed in the third parameter to sqlite3_open_v2().
2773 **
2774 ** <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or
2775 ** "private". ^Setting it to "shared" is equivalent to setting the
2776 ** SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to
2777 ** sqlite3_open_v2(). ^Setting the cache parameter to "private" is
2778 ** equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit.
2779 ** ^If sqlite3_open_v2() is used and the "cache" parameter is present in
2780 ** a URI filename, its value overrides any behavior requested by setting
2781 ** SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag.
2782 ** </ul>
2783 **
2784 ** ^Specifying an unknown parameter in the query component of a URI is not an
2785 ** error. Future versions of SQLite might understand additional query
2786 ** parameters. See "[query parameters with special meaning to SQLite]" for
2787 ** additional information.
2788 **
2789 ** [[URI filename examples]] <h3>URI filename examples</h3>
2790 **
2791 ** <table border="1" align=center cellpadding=5>
2792 ** <tr><th> URI filenames <th> Results
2793 ** <tr><td> file:data.db <td>
2794 ** Open the file "data.db" in the current directory.
2795 ** <tr><td> file:/home/fred/data.db<br>
2796 ** file:///home/fred/data.db <br>
2797 ** file://localhost/home/fred/data.db <br> <td>
2798 ** Open the database file "/home/fred/data.db".
2799 ** <tr><td> file://darkstar/home/fred/data.db <td>
2800 ** An error. "darkstar" is not a recognized authority.
2801 ** <tr><td style="white-space:nowrap">
2802 ** file:///C:/Documents%20and%20Settings/fred/Desktop/data.db
2803 ** <td> Windows only: Open the file "data.db" on fred's desktop on drive
2804 ** C:. Note that the %20 escaping in this example is not strictly
2805 ** necessary - space characters can be used literally
2806 ** in URI filenames.
2807 ** <tr><td> file:data.db?mode=ro&cache=private <td>
2808 ** Open file "data.db" in the current directory for read-only access.
2809 ** Regardless of whether or not shared-cache mode is enabled by
2810 ** default, use a private cache.
2811 ** <tr><td> file:/home/fred/data.db?vfs=unix-nolock <td>
2812 ** Open file "/home/fred/data.db". Use the special VFS "unix-nolock".
2813 ** <tr><td> file:data.db?mode=readonly <td>
2814 ** An error. "readonly" is not a valid option for the "mode" parameter.
2815 ** </table>
2816 **
2817 ** ^URI hexadecimal escape sequences (%HH) are supported within the path and
2818 ** query components of a URI. A hexadecimal escape sequence consists of a
2819 ** percent sign - "%" - followed by exactly two hexadecimal digits
2820 ** specifying an octet value. ^Before the path or query components of a
2821 ** URI filename are interpreted, they are encoded using UTF-8 and all
2822 ** hexadecimal escape sequences replaced by a single byte containing the
2823 ** corresponding octet. If this process generates an invalid UTF-8 encoding,
2824 ** the results are undefined.
2825 **
2826 ** <b>Note to Windows users:</b> The encoding used for the filename argument
2827 ** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
2828 ** codepage is currently defined. Filenames containing international
2829 ** characters must be converted to UTF-8 prior to passing them into
2830 ** sqlite3_open() or sqlite3_open_v2().
2831 **
2832 ** <b>Note to Windows Runtime users:</b> The temporary directory must be set
2833 ** prior to calling sqlite3_open() or sqlite3_open_v2(). Otherwise, various
2834 ** features that require the use of temporary files may fail.
2835 **
2836 ** See also: [sqlite3_temp_directory]
2837 */
2839  const char *filename, /* Database filename (UTF-8) */
2840  sqlite3 **ppDb /* OUT: SQLite db handle */
2841 );
2843  const void *filename, /* Database filename (UTF-16) */
2844  sqlite3 **ppDb /* OUT: SQLite db handle */
2845 );
2847  const char *filename, /* Database filename (UTF-8) */
2848  sqlite3 **ppDb, /* OUT: SQLite db handle */
2849  int flags, /* Flags */
2850  const char *zVfs /* Name of VFS module to use */
2851 );
2852 
2853 /*
2854 ** CAPI3REF: Obtain Values For URI Parameters
2855 **
2856 ** These are utility routines, useful to VFS implementations, that check
2857 ** to see if a database file was a URI that contained a specific query
2858 ** parameter, and if so obtains the value of that query parameter.
2859 **
2860 ** If F is the database filename pointer passed into the xOpen() method of
2861 ** a VFS implementation when the flags parameter to xOpen() has one or
2862 ** more of the [SQLITE_OPEN_URI] or [SQLITE_OPEN_MAIN_DB] bits set and
2863 ** P is the name of the query parameter, then
2864 ** sqlite3_uri_parameter(F,P) returns the value of the P
2865 ** parameter if it exists or a NULL pointer if P does not appear as a
2866 ** query parameter on F. If P is a query parameter of F
2867 ** has no explicit value, then sqlite3_uri_parameter(F,P) returns
2868 ** a pointer to an empty string.
2869 **
2870 ** The sqlite3_uri_boolean(F,P,B) routine assumes that P is a boolean
2871 ** parameter and returns true (1) or false (0) according to the value
2872 ** of P. The sqlite3_uri_boolean(F,P,B) routine returns true (1) if the
2873 ** value of query parameter P is one of "yes", "true", or "on" in any
2874 ** case or if the value begins with a non-zero number. The
2875 ** sqlite3_uri_boolean(F,P,B) routines returns false (0) if the value of
2876 ** query parameter P is one of "no", "false", or "off" in any case or
2877 ** if the value begins with a numeric zero. If P is not a query
2878 ** parameter on F or if the value of P is does not match any of the
2879 ** above, then sqlite3_uri_boolean(F,P,B) returns (B!=0).
2880 **
2881 ** The sqlite3_uri_int64(F,P,D) routine converts the value of P into a
2882 ** 64-bit signed integer and returns that integer, or D if P does not
2883 ** exist. If the value of P is something other than an integer, then
2884 ** zero is returned.
2885 **
2886 ** If F is a NULL pointer, then sqlite3_uri_parameter(F,P) returns NULL and
2887 ** sqlite3_uri_boolean(F,P,B) returns B. If F is not a NULL pointer and
2888 ** is not a database file pathname pointer that SQLite passed into the xOpen
2889 ** VFS method, then the behavior of this routine is undefined and probably
2890 ** undesirable.
2891 */
2892 SQLITE_API const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam);
2893 SQLITE_API int sqlite3_uri_boolean(const char *zFile, const char *zParam, int bDefault);
2894 SQLITE_API sqlite3_int64 sqlite3_uri_int64(const char*, const char*, sqlite3_int64);
2895 
2896 
2897 /*
2898 ** CAPI3REF: Error Codes And Messages
2899 **
2900 ** ^The sqlite3_errcode() interface returns the numeric [result code] or
2901 ** [extended result code] for the most recent failed sqlite3_* API call
2902 ** associated with a [database connection]. If a prior API call failed
2903 ** but the most recent API call succeeded, the return value from
2904 ** sqlite3_errcode() is undefined. ^The sqlite3_extended_errcode()
2905 ** interface is the same except that it always returns the
2906 ** [extended result code] even when extended result codes are
2907 ** disabled.
2908 **
2909 ** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
2910 ** text that describes the error, as either UTF-8 or UTF-16 respectively.
2911 ** ^(Memory to hold the error message string is managed internally.
2912 ** The application does not need to worry about freeing the result.
2913 ** However, the error string might be overwritten or deallocated by
2914 ** subsequent calls to other SQLite interface functions.)^
2915 **
2916 ** ^The sqlite3_errstr() interface returns the English-language text
2917 ** that describes the [result code], as UTF-8.
2918 ** ^(Memory to hold the error message string is managed internally
2919 ** and must not be freed by the application)^.
2920 **
2921 ** When the serialized [threading mode] is in use, it might be the
2922 ** case that a second error occurs on a separate thread in between
2923 ** the time of the first error and the call to these interfaces.
2924 ** When that happens, the second error will be reported since these
2925 ** interfaces always report the most recent result. To avoid
2926 ** this, each thread can obtain exclusive use of the [database connection] D
2927 ** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
2928 ** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
2929 ** all calls to the interfaces listed here are completed.
2930 **
2931 ** If an interface fails with SQLITE_MISUSE, that means the interface
2932 ** was invoked incorrectly by the application. In that case, the
2933 ** error code and message may or may not be set.
2934 */
2937 SQLITE_API const char *sqlite3_errmsg(sqlite3*);
2938 SQLITE_API const void *sqlite3_errmsg16(sqlite3*);
2939 SQLITE_API const char *sqlite3_errstr(int);
2940 
2941 /*
2942 ** CAPI3REF: SQL Statement Object
2943 ** KEYWORDS: {prepared statement} {prepared statements}
2944 **
2945 ** An instance of this object represents a single SQL statement.
2946 ** This object is variously known as a "prepared statement" or a
2947 ** "compiled SQL statement" or simply as a "statement".
2948 **
2949 ** The life of a statement object goes something like this:
2950 **
2951 ** <ol>
2952 ** <li> Create the object using [sqlite3_prepare_v2()] or a related
2953 ** function.
2954 ** <li> Bind values to [host parameters] using the sqlite3_bind_*()
2955 ** interfaces.
2956 ** <li> Run the SQL by calling [sqlite3_step()] one or more times.
2957 ** <li> Reset the statement using [sqlite3_reset()] then go back
2958 ** to step 2. Do this zero or more times.
2959 ** <li> Destroy the object using [sqlite3_finalize()].
2960 ** </ol>
2961 **
2962 ** Refer to documentation on individual methods above for additional
2963 ** information.
2964 */
2966 
2967 /*
2968 ** CAPI3REF: Run-time Limits
2969 **
2970 ** ^(This interface allows the size of various constructs to be limited
2971 ** on a connection by connection basis. The first parameter is the
2972 ** [database connection] whose limit is to be set or queried. The
2973 ** second parameter is one of the [limit categories] that define a
2974 ** class of constructs to be size limited. The third parameter is the
2975 ** new limit for that construct.)^
2976 **
2977 ** ^If the new limit is a negative number, the limit is unchanged.
2978 ** ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a
2979 ** [limits | hard upper bound]
2980 ** set at compile-time by a C preprocessor macro called
2981 ** [limits | SQLITE_MAX_<i>NAME</i>].
2982 ** (The "_LIMIT_" in the name is changed to "_MAX_".))^
2983 ** ^Attempts to increase a limit above its hard upper bound are
2984 ** silently truncated to the hard upper bound.
2985 **
2986 ** ^Regardless of whether or not the limit was changed, the
2987 ** [sqlite3_limit()] interface returns the prior value of the limit.
2988 ** ^Hence, to find the current value of a limit without changing it,
2989 ** simply invoke this interface with the third parameter set to -1.
2990 **
2991 ** Run-time limits are intended for use in applications that manage
2992 ** both their own internal database and also databases that are controlled
2993 ** by untrusted external sources. An example application might be a
2994 ** web browser that has its own databases for storing history and
2995 ** separate databases controlled by JavaScript applications downloaded
2996 ** off the Internet. The internal databases can be given the
2997 ** large, default limits. Databases managed by external sources can
2998 ** be given much smaller limits designed to prevent a denial of service
2999 ** attack. Developers might also want to use the [sqlite3_set_authorizer()]
3000 ** interface to further control untrusted SQL. The size of the database
3001 ** created by an untrusted script can be contained using the
3002 ** [max_page_count] [PRAGMA].
3003 **
3004 ** New run-time limit categories may be added in future releases.
3005 */
3006 SQLITE_API int sqlite3_limit(sqlite3*, int id, int newVal);
3007 
3008 /*
3009 ** CAPI3REF: Run-Time Limit Categories
3010 ** KEYWORDS: {limit category} {*limit categories}
3011 **
3012 ** These constants define various performance limits
3013 ** that can be lowered at run-time using [sqlite3_limit()].
3014 ** The synopsis of the meanings of the various limits is shown below.
3015 ** Additional information is available at [limits | Limits in SQLite].
3016 **
3017 ** <dl>
3018 ** [[SQLITE_LIMIT_LENGTH]] ^(<dt>SQLITE_LIMIT_LENGTH</dt>
3019 ** <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^
3020 **
3021 ** [[SQLITE_LIMIT_SQL_LENGTH]] ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt>
3022 ** <dd>The maximum length of an SQL statement, in bytes.</dd>)^
3023 **
3024 ** [[SQLITE_LIMIT_COLUMN]] ^(<dt>SQLITE_LIMIT_COLUMN</dt>
3025 ** <dd>The maximum number of columns in a table definition or in the
3026 ** result set of a [SELECT] or the maximum number of columns in an index
3027 ** or in an ORDER BY or GROUP BY clause.</dd>)^
3028 **
3029 ** [[SQLITE_LIMIT_EXPR_DEPTH]] ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
3030 ** <dd>The maximum depth of the parse tree on any expression.</dd>)^
3031 **
3032 ** [[SQLITE_LIMIT_COMPOUND_SELECT]] ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
3033 ** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^
3034 **
3035 ** [[SQLITE_LIMIT_VDBE_OP]] ^(<dt>SQLITE_LIMIT_VDBE_OP</dt>
3036 ** <dd>The maximum number of instructions in a virtual machine program
3037 ** used to implement an SQL statement. This limit is not currently
3038 ** enforced, though that might be added in some future release of
3039 ** SQLite.</dd>)^
3040 **
3041 ** [[SQLITE_LIMIT_FUNCTION_ARG]] ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
3042 ** <dd>The maximum number of arguments on a function.</dd>)^
3043 **
3044 ** [[SQLITE_LIMIT_ATTACHED]] ^(<dt>SQLITE_LIMIT_ATTACHED</dt>
3045 ** <dd>The maximum number of [ATTACH | attached databases].)^</dd>
3046 **
3047 ** [[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]]
3048 ** ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
3049 ** <dd>The maximum length of the pattern argument to the [LIKE] or
3050 ** [GLOB] operators.</dd>)^
3051 **
3052 ** [[SQLITE_LIMIT_VARIABLE_NUMBER]]
3053 ** ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
3054 ** <dd>The maximum index number of any [parameter] in an SQL statement.)^
3055 **
3056 ** [[SQLITE_LIMIT_TRIGGER_DEPTH]] ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt>
3057 ** <dd>The maximum depth of recursion for triggers.</dd>)^
3058 ** </dl>
3059 */
3060 #define SQLITE_LIMIT_LENGTH 0
3061 #define SQLITE_LIMIT_SQL_LENGTH 1
3062 #define SQLITE_LIMIT_COLUMN 2
3063 #define SQLITE_LIMIT_EXPR_DEPTH 3
3064 #define SQLITE_LIMIT_COMPOUND_SELECT 4
3065 #define SQLITE_LIMIT_VDBE_OP 5
3066 #define SQLITE_LIMIT_FUNCTION_ARG 6
3067 #define SQLITE_LIMIT_ATTACHED 7
3068 #define SQLITE_LIMIT_LIKE_PATTERN_LENGTH 8
3069 #define SQLITE_LIMIT_VARIABLE_NUMBER 9
3070 #define SQLITE_LIMIT_TRIGGER_DEPTH 10
3071 
3072 /*
3073 ** CAPI3REF: Compiling An SQL Statement
3074 ** KEYWORDS: {SQL statement compiler}
3075 **
3076 ** To execute an SQL query, it must first be compiled into a byte-code
3077 ** program using one of these routines.
3078 **
3079 ** The first argument, "db", is a [database connection] obtained from a
3080 ** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or
3081 ** [sqlite3_open16()]. The database connection must not have been closed.
3082 **
3083 ** The second argument, "zSql", is the statement to be compiled, encoded
3084 ** as either UTF-8 or UTF-16. The sqlite3_prepare() and sqlite3_prepare_v2()
3085 ** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()
3086 ** use UTF-16.
3087 **
3088 ** ^If the nByte argument is less than zero, then zSql is read up to the
3089 ** first zero terminator. ^If nByte is non-negative, then it is the maximum
3090 ** number of bytes read from zSql. ^When nByte is non-negative, the
3091 ** zSql string ends at either the first '\000' or '\u0000' character or
3092 ** the nByte-th byte, whichever comes first. If the caller knows
3093 ** that the supplied string is nul-terminated, then there is a small
3094 ** performance advantage to be gained by passing an nByte parameter that
3095 ** is equal to the number of bytes in the input string <i>including</i>
3096 ** the nul-terminator bytes as this saves SQLite from having to
3097 ** make a copy of the input string.
3098 **
3099 ** ^If pzTail is not NULL then *pzTail is made to point to the first byte
3100 ** past the end of the first SQL statement in zSql. These routines only
3101 ** compile the first statement in zSql, so *pzTail is left pointing to
3102 ** what remains uncompiled.
3103 **
3104 ** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
3105 ** executed using [sqlite3_step()]. ^If there is an error, *ppStmt is set
3106 ** to NULL. ^If the input text contains no SQL (if the input is an empty
3107 ** string or a comment) then *ppStmt is set to NULL.
3108 ** The calling procedure is responsible for deleting the compiled
3109 ** SQL statement using [sqlite3_finalize()] after it has finished with it.
3110 ** ppStmt may not be NULL.
3111 **
3112 ** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK];
3113 ** otherwise an [error code] is returned.
3114 **
3115 ** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are
3116 ** recommended for all new programs. The two older interfaces are retained
3117 ** for backwards compatibility, but their use is discouraged.
3118 ** ^In the "v2" interfaces, the prepared statement
3119 ** that is returned (the [sqlite3_stmt] object) contains a copy of the
3120 ** original SQL text. This causes the [sqlite3_step()] interface to
3121 ** behave differently in three ways:
3122 **
3123 ** <ol>
3124 ** <li>
3125 ** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
3126 ** always used to do, [sqlite3_step()] will automatically recompile the SQL
3127 ** statement and try to run it again. As many as [SQLITE_MAX_SCHEMA_RETRY]
3128 ** retries will occur before sqlite3_step() gives up and returns an error.
3129 ** </li>
3130 **
3131 ** <li>
3132 ** ^When an error occurs, [sqlite3_step()] will return one of the detailed
3133 ** [error codes] or [extended error codes]. ^The legacy behavior was that
3134 ** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
3135 ** and the application would have to make a second call to [sqlite3_reset()]
3136 ** in order to find the underlying cause of the problem. With the "v2" prepare
3137 ** interfaces, the underlying reason for the error is returned immediately.
3138 ** </li>
3139 **
3140 ** <li>
3141 ** ^If the specific value bound to [parameter | host parameter] in the
3142 ** WHERE clause might influence the choice of query plan for a statement,
3143 ** then the statement will be automatically recompiled, as if there had been
3144 ** a schema change, on the first [sqlite3_step()] call following any change
3145 ** to the [sqlite3_bind_text | bindings] of that [parameter].
3146 ** ^The specific value of WHERE-clause [parameter] might influence the
3147 ** choice of query plan if the parameter is the left-hand side of a [LIKE]
3148 ** or [GLOB] operator or if the parameter is compared to an indexed column
3149 ** and the [SQLITE_ENABLE_STAT3] compile-time option is enabled.
3150 ** </li>
3151 ** </ol>
3152 */
3154  sqlite3 *db, /* Database handle */
3155  const char *zSql, /* SQL statement, UTF-8 encoded */
3156  int nByte, /* Maximum length of zSql in bytes. */
3157  sqlite3_stmt **ppStmt, /* OUT: Statement handle */
3158  const char **pzTail /* OUT: Pointer to unused portion of zSql */
3159 );
3161  sqlite3 *db, /* Database handle */
3162  const char *zSql, /* SQL statement, UTF-8 encoded */
3163  int nByte, /* Maximum length of zSql in bytes. */
3164  sqlite3_stmt **ppStmt, /* OUT: Statement handle */
3165  const char **pzTail /* OUT: Pointer to unused portion of zSql */
3166 );
3168  sqlite3 *db, /* Database handle */
3169  const void *zSql, /* SQL statement, UTF-16 encoded */
3170  int nByte, /* Maximum length of zSql in bytes. */
3171  sqlite3_stmt **ppStmt, /* OUT: Statement handle */
3172  const void **pzTail /* OUT: Pointer to unused portion of zSql */
3173 );
3175  sqlite3 *db, /* Database handle */
3176  const void *zSql, /* SQL statement, UTF-16 encoded */
3177  int nByte, /* Maximum length of zSql in bytes. */
3178  sqlite3_stmt **ppStmt, /* OUT: Statement handle */
3179  const void **pzTail /* OUT: Pointer to unused portion of zSql */
3180 );
3181 
3182 /*
3183 ** CAPI3REF: Retrieving Statement SQL
3184 **
3185 ** ^This interface can be used to retrieve a saved copy of the original
3186 ** SQL text used to create a [prepared statement] if that statement was
3187 ** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
3188 */
3189 SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt);
3190 
3191 /*
3192 ** CAPI3REF: Determine If An SQL Statement Writes The Database
3193 **
3194 ** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if
3195 ** and only if the [prepared statement] X makes no direct changes to
3196 ** the content of the database file.
3197 **
3198 ** Note that [application-defined SQL functions] or
3199 ** [virtual tables] might change the database indirectly as a side effect.
3200 ** ^(For example, if an application defines a function "eval()" that
3201 ** calls [sqlite3_exec()], then the following SQL statement would
3202 ** change the database file through side-effects:
3203 **
3204 ** <blockquote><pre>
3205 ** SELECT eval('DELETE FROM t1') FROM t2;
3206 ** </pre></blockquote>
3207 **
3208 ** But because the [SELECT] statement does not change the database file
3209 ** directly, sqlite3_stmt_readonly() would still return true.)^
3210 **
3211 ** ^Transaction control statements such as [BEGIN], [COMMIT], [ROLLBACK],
3212 ** [SAVEPOINT], and [RELEASE] cause sqlite3_stmt_readonly() to return true,
3213 ** since the statements themselves do not actually modify the database but
3214 ** rather they control the timing of when other statements modify the
3215 ** database. ^The [ATTACH] and [DETACH] statements also cause
3216 ** sqlite3_stmt_readonly() to return true since, while those statements
3217 ** change the configuration of a database connection, they do not make
3218 ** changes to the content of the database files on disk.
3219 */
3221 
3222 /*
3223 ** CAPI3REF: Determine If A Prepared Statement Has Been Reset
3224 **
3225 ** ^The sqlite3_stmt_busy(S) interface returns true (non-zero) if the
3226 ** [prepared statement] S has been stepped at least once using
3227 ** [sqlite3_step(S)] but has not run to completion and/or has not
3228 ** been reset using [sqlite3_reset(S)]. ^The sqlite3_stmt_busy(S)
3229 ** interface returns false if S is a NULL pointer. If S is not a
3230 ** NULL pointer and is not a pointer to a valid [prepared statement]
3231 ** object, then the behavior is undefined and probably undesirable.
3232 **
3233 ** This interface can be used in combination [sqlite3_next_stmt()]
3234 ** to locate all prepared statements associated with a database
3235 ** connection that are in need of being reset. This can be used,
3236 ** for example, in diagnostic routines to search for prepared
3237 ** statements that are holding a transaction open.
3238 */
3240 
3241 /*
3242 ** CAPI3REF: Dynamically Typed Value Object
3243 ** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
3244 **
3245 ** SQLite uses the sqlite3_value object to represent all values
3246 ** that can be stored in a database table. SQLite uses dynamic typing
3247 ** for the values it stores. ^Values stored in sqlite3_value objects
3248 ** can be integers, floating point values, strings, BLOBs, or NULL.
3249 **
3250 ** An sqlite3_value object may be either "protected" or "unprotected".
3251 ** Some interfaces require a protected sqlite3_value. Other interfaces
3252 ** will accept either a protected or an unprotected sqlite3_value.
3253 ** Every interface that accepts sqlite3_value arguments specifies
3254 ** whether or not it requires a protected sqlite3_value.
3255 **
3256 ** The terms "protected" and "unprotected" refer to whether or not
3257 ** a mutex is held. An internal mutex is held for a protected
3258 ** sqlite3_value object but no mutex is held for an unprotected
3259 ** sqlite3_value object. If SQLite is compiled to be single-threaded
3260 ** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
3261 ** or if SQLite is run in one of reduced mutex modes
3262 ** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
3263 ** then there is no distinction between protected and unprotected
3264 ** sqlite3_value objects and they can be used interchangeably. However,
3265 ** for maximum code portability it is recommended that applications
3266 ** still make the distinction between protected and unprotected
3267 ** sqlite3_value objects even when not strictly required.
3268 **
3269 ** ^The sqlite3_value objects that are passed as parameters into the
3270 ** implementation of [application-defined SQL functions] are protected.
3271 ** ^The sqlite3_value object returned by
3272 ** [sqlite3_column_value()] is unprotected.
3273 ** Unprotected sqlite3_value objects may only be used with
3274 ** [sqlite3_result_value()] and [sqlite3_bind_value()].
3275 ** The [sqlite3_value_blob | sqlite3_value_type()] family of
3276 ** interfaces require protected sqlite3_value objects.
3277 */
3278 typedef struct Mem sqlite3_value;
3279 
3280 /*
3281 ** CAPI3REF: SQL Function Context Object
3282 **
3283 ** The context in which an SQL function executes is stored in an
3284 ** sqlite3_context object. ^A pointer to an sqlite3_context object
3285 ** is always first parameter to [application-defined SQL functions].
3286 ** The application-defined SQL function implementation will pass this
3287 ** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
3288 ** [sqlite3_aggregate_context()], [sqlite3_user_data()],
3289 ** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
3290 ** and/or [sqlite3_set_auxdata()].
3291 */
3293 
3294 /*
3295 ** CAPI3REF: Binding Values To Prepared Statements
3296 ** KEYWORDS: {host parameter} {host parameters} {host parameter name}
3297 ** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
3298 **
3299 ** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants,
3300 ** literals may be replaced by a [parameter] that matches one of following
3301 ** templates:
3302 **
3303 ** <ul>
3304 ** <li> ?
3305 ** <li> ?NNN
3306 ** <li> :VVV
3307 ** <li> @VVV
3308 ** <li> $VVV
3309 ** </ul>
3310 **
3311 ** In the templates above, NNN represents an integer literal,
3312 ** and VVV represents an alphanumeric identifier.)^ ^The values of these
3313 ** parameters (also called "host parameter names" or "SQL parameters")
3314 ** can be set using the sqlite3_bind_*() routines defined here.
3315 **
3316 ** ^The first argument to the sqlite3_bind_*() routines is always
3317 ** a pointer to the [sqlite3_stmt] object returned from
3318 ** [sqlite3_prepare_v2()] or its variants.
3319 **
3320 ** ^The second argument is the index of the SQL parameter to be set.
3321 ** ^The leftmost SQL parameter has an index of 1. ^When the same named
3322 ** SQL parameter is used more than once, second and subsequent
3323 ** occurrences have the same index as the first occurrence.
3324 ** ^The index for named parameters can be looked up using the
3325 ** [sqlite3_bind_parameter_index()] API if desired. ^The index
3326 ** for "?NNN" parameters is the value of NNN.
3327 ** ^The NNN value must be between 1 and the [sqlite3_limit()]
3328 ** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
3329 **
3330 ** ^The third argument is the value to bind to the parameter.
3331 ** ^If the third parameter to sqlite3_bind_text() or sqlite3_bind_text16()
3332 ** or sqlite3_bind_blob() is a NULL pointer then the fourth parameter
3333 ** is ignored and the end result is the same as sqlite3_bind_null().
3334 **
3335 ** ^(In those routines that have a fourth argument, its value is the
3336 ** number of bytes in the parameter. To be clear: the value is the
3337 ** number of <u>bytes</u> in the value, not the number of characters.)^
3338 ** ^If the fourth parameter to sqlite3_bind_text() or sqlite3_bind_text16()
3339 ** is negative, then the length of the string is
3340 ** the number of bytes up to the first zero terminator.
3341 ** If the fourth parameter to sqlite3_bind_blob() is negative, then
3342 ** the behavior is undefined.
3343 ** If a non-negative fourth parameter is provided to sqlite3_bind_text()
3344 ** or sqlite3_bind_text16() then that parameter must be the byte offset
3345 ** where the NUL terminator would occur assuming the string were NUL
3346 ** terminated. If any NUL characters occur at byte offsets less than
3347 ** the value of the fourth parameter then the resulting string value will
3348 ** contain embedded NULs. The result of expressions involving strings
3349 ** with embedded NULs is undefined.
3350 **
3351 ** ^The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
3352 ** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
3353 ** string after SQLite has finished with it. ^The destructor is called
3354 ** to dispose of the BLOB or string even if the call to sqlite3_bind_blob(),
3355 ** sqlite3_bind_text(), or sqlite3_bind_text16() fails.
3356 ** ^If the fifth argument is
3357 ** the special value [SQLITE_STATIC], then SQLite assumes that the
3358 ** information is in static, unmanaged space and does not need to be freed.
3359 ** ^If the fifth argument has the value [SQLITE_TRANSIENT], then
3360 ** SQLite makes its own private copy of the data immediately, before
3361 ** the sqlite3_bind_*() routine returns.
3362 **
3363 ** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
3364 ** is filled with zeroes. ^A zeroblob uses a fixed amount of memory
3365 ** (just an integer to hold its size) while it is being processed.
3366 ** Zeroblobs are intended to serve as placeholders for BLOBs whose
3367 ** content is later written using
3368 ** [sqlite3_blob_open | incremental BLOB I/O] routines.
3369 ** ^A negative value for the zeroblob results in a zero-length BLOB.
3370 **
3371 ** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer
3372 ** for the [prepared statement] or with a prepared statement for which
3373 ** [sqlite3_step()] has been called more recently than [sqlite3_reset()],
3374 ** then the call will return [SQLITE_MISUSE]. If any sqlite3_bind_()
3375 ** routine is passed a [prepared statement] that has been finalized, the
3376 ** result is undefined and probably harmful.
3377 **
3378 ** ^Bindings are not cleared by the [sqlite3_reset()] routine.
3379 ** ^Unbound parameters are interpreted as NULL.
3380 **
3381 ** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an
3382 ** [error code] if anything goes wrong.
3383 ** ^[SQLITE_RANGE] is returned if the parameter
3384 ** index is out of range. ^[SQLITE_NOMEM] is returned if malloc() fails.
3385 **
3386 ** See also: [sqlite3_bind_parameter_count()],
3387 ** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
3388 */
3389 SQLITE_API int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*));
3390 SQLITE_API int sqlite3_bind_double(sqlite3_stmt*, int, double);
3391 SQLITE_API int sqlite3_bind_int(sqlite3_stmt*, int, int);
3392 SQLITE_API int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);
3394 SQLITE_API int sqlite3_bind_text(sqlite3_stmt*, int, const char*, int n, void(*)(void*));
3395 SQLITE_API int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*));
3398 
3399 /*
3400 ** CAPI3REF: Number Of SQL Parameters
3401 **
3402 ** ^This routine can be used to find the number of [SQL parameters]
3403 ** in a [prepared statement]. SQL parameters are tokens of the
3404 ** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
3405 ** placeholders for values that are [sqlite3_bind_blob | bound]
3406 ** to the parameters at a later time.
3407 **
3408 ** ^(This routine actually returns the index of the largest (rightmost)
3409 ** parameter. For all forms except ?NNN, this will correspond to the
3410 ** number of unique parameters. If parameters of the ?NNN form are used,
3411 ** there may be gaps in the list.)^
3412 **
3413 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
3414 ** [sqlite3_bind_parameter_name()], and
3415 ** [sqlite3_bind_parameter_index()].
3416 */
3418 
3419 /*
3420 ** CAPI3REF: Name Of A Host Parameter
3421 **
3422 ** ^The sqlite3_bind_parameter_name(P,N) interface returns
3423 ** the name of the N-th [SQL parameter] in the [prepared statement] P.
3424 ** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
3425 ** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
3426 ** respectively.
3427 ** In other words, the initial ":" or "$" or "@" or "?"
3428 ** is included as part of the name.)^
3429 ** ^Parameters of the form "?" without a following integer have no name
3430 ** and are referred to as "nameless" or "anonymous parameters".
3431 **
3432 ** ^The first host parameter has an index of 1, not 0.
3433 **
3434 ** ^If the value N is out of range or if the N-th parameter is
3435 ** nameless, then NULL is returned. ^The returned string is
3436 ** always in UTF-8 encoding even if the named parameter was
3437 ** originally specified as UTF-16 in [sqlite3_prepare16()] or
3438 ** [sqlite3_prepare16_v2()].
3439 **
3440 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
3441 ** [sqlite3_bind_parameter_count()], and
3442 ** [sqlite3_bind_parameter_index()].
3443 */
3445 
3446 /*
3447 ** CAPI3REF: Index Of A Parameter With A Given Name
3448 **
3449 ** ^Return the index of an SQL parameter given its name. ^The
3450 ** index value returned is suitable for use as the second
3451 ** parameter to [sqlite3_bind_blob|sqlite3_bind()]. ^A zero
3452 ** is returned if no matching parameter is found. ^The parameter
3453 ** name must be given in UTF-8 even if the original statement
3454 ** was prepared from UTF-16 text using [sqlite3_prepare16_v2()].
3455 **
3456 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
3457 ** [sqlite3_bind_parameter_count()], and
3458 ** [sqlite3_bind_parameter_index()].
3459 */
3460 SQLITE_API int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName);
3461 
3462 /*
3463 ** CAPI3REF: Reset All Bindings On A Prepared Statement
3464 **
3465 ** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset
3466 ** the [sqlite3_bind_blob | bindings] on a [prepared statement].
3467 ** ^Use this routine to reset all host parameters to NULL.
3468 */
3470 
3471 /*
3472 ** CAPI3REF: Number Of Columns In A Result Set
3473 **
3474 ** ^Return the number of columns in the result set returned by the
3475 ** [prepared statement]. ^This routine returns 0 if pStmt is an SQL
3476 ** statement that does not return data (for example an [UPDATE]).
3477 **
3478 ** See also: [sqlite3_data_count()]
3479 */
3481 
3482 /*
3483 ** CAPI3REF: Column Names In A Result Set
3484 **
3485 ** ^These routines return the name assigned to a particular column
3486 ** in the result set of a [SELECT] statement. ^The sqlite3_column_name()
3487 ** interface returns a pointer to a zero-terminated UTF-8 string
3488 ** and sqlite3_column_name16() returns a pointer to a zero-terminated
3489 ** UTF-16 string. ^The first parameter is the [prepared statement]
3490 ** that implements the [SELECT] statement. ^The second parameter is the
3491 ** column number. ^The leftmost column is number 0.
3492 **
3493 ** ^The returned string pointer is valid until either the [prepared statement]
3494 ** is destroyed by [sqlite3_finalize()] or until the statement is automatically
3495 ** reprepared by the first call to [sqlite3_step()] for a particular run
3496 ** or until the next call to
3497 ** sqlite3_column_name() or sqlite3_column_name16() on the same column.
3498 **
3499 ** ^If sqlite3_malloc() fails during the processing of either routine
3500 ** (for example during a conversion from UTF-8 to UTF-16) then a
3501 ** NULL pointer is returned.
3502 **
3503 ** ^The name of a result column is the value of the "AS" clause for
3504 ** that column, if there is an AS clause. If there is no AS clause
3505 ** then the name of the column is unspecified and may change from
3506 ** one release of SQLite to the next.
3507 */
3508 SQLITE_API const char *sqlite3_column_name(sqlite3_stmt*, int N);
3509 SQLITE_API const void *sqlite3_column_name16(sqlite3_stmt*, int N);
3510 
3511 /*
3512 ** CAPI3REF: Source Of Data In A Query Result
3513 **
3514 ** ^These routines provide a means to determine the database, table, and
3515 ** table column that is the origin of a particular result column in
3516 ** [SELECT] statement.
3517 ** ^The name of the database or table or column can be returned as
3518 ** either a UTF-8 or UTF-16 string. ^The _database_ routines return
3519 ** the database name, the _table_ routines return the table name, and
3520 ** the origin_ routines return the column name.
3521 ** ^The returned string is valid until the [prepared statement] is destroyed
3522 ** using [sqlite3_finalize()] or until the statement is automatically
3523 ** reprepared by the first call to [sqlite3_step()] for a particular run
3524 ** or until the same information is requested
3525 ** again in a different encoding.
3526 **
3527 ** ^The names returned are the original un-aliased names of the
3528 ** database, table, and column.
3529 **
3530 ** ^The first argument to these interfaces is a [prepared statement].
3531 ** ^These functions return information about the Nth result column returned by
3532 ** the statement, where N is the second function argument.
3533 ** ^The left-most column is column 0 for these routines.
3534 **
3535 ** ^If the Nth column returned by the statement is an expression or
3536 ** subquery and is not a column value, then all of these functions return
3537 ** NULL. ^These routine might also return NULL if a memory allocation error
3538 ** occurs. ^Otherwise, they return the name of the attached database, table,
3539 ** or column that query result column was extracted from.
3540 **
3541 ** ^As with all other SQLite APIs, those whose names end with "16" return
3542 ** UTF-16 encoded strings and the other functions return UTF-8.
3543 **
3544 ** ^These APIs are only available if the library was compiled with the
3545 ** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol.
3546 **
3547 ** If two or more threads call one or more of these routines against the same
3548 ** prepared statement and column at the same time then the results are
3549 ** undefined.
3550 **
3551 ** If two or more threads call one or more
3552 ** [sqlite3_column_database_name | column metadata interfaces]
3553 ** for the same [prepared statement] and result column
3554 ** at the same time then the results are undefined.
3555 */
3562 
3563 /*
3564 ** CAPI3REF: Declared Datatype Of A Query Result
3565 **
3566 ** ^(The first parameter is a [prepared statement].
3567 ** If this statement is a [SELECT] statement and the Nth column of the
3568 ** returned result set of that [SELECT] is a table column (not an
3569 ** expression or subquery) then the declared type of the table
3570 ** column is returned.)^ ^If the Nth column of the result set is an
3571 ** expression or subquery, then a NULL pointer is returned.
3572 ** ^The returned string is always UTF-8 encoded.
3573 **
3574 ** ^(For example, given the database schema:
3575 **
3576 ** CREATE TABLE t1(c1 VARIANT);
3577 **
3578 ** and the following statement to be compiled:
3579 **
3580 ** SELECT c1 + 1, c1 FROM t1;
3581 **
3582 ** this routine would return the string "VARIANT" for the second result
3583 ** column (i==1), and a NULL pointer for the first result column (i==0).)^
3584 **
3585 ** ^SQLite uses dynamic run-time typing. ^So just because a column
3586 ** is declared to contain a particular type does not mean that the
3587 ** data stored in that column is of the declared type. SQLite is
3588 ** strongly typed, but the typing is dynamic not static. ^Type
3589 ** is associated with individual values, not with the containers
3590 ** used to hold those values.
3591 */
3594 
3595 /*
3596 ** CAPI3REF: Evaluate An SQL Statement
3597 **
3598 ** After a [prepared statement] has been prepared using either
3599 ** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy
3600 ** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
3601 ** must be called one or more times to evaluate the statement.
3602 **
3603 ** The details of the behavior of the sqlite3_step() interface depend
3604 ** on whether the statement was prepared using the newer "v2" interface
3605 ** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy
3606 ** interface [sqlite3_prepare()] and [sqlite3_prepare16()]. The use of the
3607 ** new "v2" interface is recommended for new applications but the legacy
3608 ** interface will continue to be supported.
3609 **
3610 ** ^In the legacy interface, the return value will be either [SQLITE_BUSY],
3611 ** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
3612 ** ^With the "v2" interface, any of the other [result codes] or
3613 ** [extended result codes] might be returned as well.
3614 **
3615 ** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
3616 ** database locks it needs to do its job. ^If the statement is a [COMMIT]
3617 ** or occurs outside of an explicit transaction, then you can retry the
3618 ** statement. If the statement is not a [COMMIT] and occurs within an
3619 ** explicit transaction then you should rollback the transaction before
3620 ** continuing.
3621 **
3622 ** ^[SQLITE_DONE] means that the statement has finished executing
3623 ** successfully. sqlite3_step() should not be called again on this virtual
3624 ** machine without first calling [sqlite3_reset()] to reset the virtual
3625 ** machine back to its initial state.
3626 **
3627 ** ^If the SQL statement being executed returns any data, then [SQLITE_ROW]
3628 ** is returned each time a new row of data is ready for processing by the
3629 ** caller. The values may be accessed using the [column access functions].
3630 ** sqlite3_step() is called again to retrieve the next row of data.
3631 **
3632 ** ^[SQLITE_ERROR] means that a run-time error (such as a constraint
3633 ** violation) has occurred. sqlite3_step() should not be called again on
3634 ** the VM. More information may be found by calling [sqlite3_errmsg()].
3635 ** ^With the legacy interface, a more specific error code (for example,
3636 ** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
3637 ** can be obtained by calling [sqlite3_reset()] on the
3638 ** [prepared statement]. ^In the "v2" interface,
3639 ** the more specific error code is returned directly by sqlite3_step().
3640 **
3641 ** [SQLITE_MISUSE] means that the this routine was called inappropriately.
3642 ** Perhaps it was called on a [prepared statement] that has
3643 ** already been [sqlite3_finalize | finalized] or on one that had
3644 ** previously returned [SQLITE_ERROR] or [SQLITE_DONE]. Or it could
3645 ** be the case that the same database connection is being used by two or
3646 ** more threads at the same moment in time.
3647 **
3648 ** For all versions of SQLite up to and including 3.6.23.1, a call to
3649 ** [sqlite3_reset()] was required after sqlite3_step() returned anything
3650 ** other than [SQLITE_ROW] before any subsequent invocation of
3651 ** sqlite3_step(). Failure to reset the prepared statement using
3652 ** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
3653 ** sqlite3_step(). But after version 3.6.23.1, sqlite3_step() began
3654 ** calling [sqlite3_reset()] automatically in this circumstance rather
3655 ** than returning [SQLITE_MISUSE]. This is not considered a compatibility
3656 ** break because any application that ever receives an SQLITE_MISUSE error
3657 ** is broken by definition. The [SQLITE_OMIT_AUTORESET] compile-time option
3658 ** can be used to restore the legacy behavior.
3659 **
3660 ** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
3661 ** API always returns a generic error code, [SQLITE_ERROR], following any
3662 ** error other than [SQLITE_BUSY] and [SQLITE_MISUSE]. You must call
3663 ** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
3664 ** specific [error codes] that better describes the error.
3665 ** We admit that this is a goofy design. The problem has been fixed
3666 ** with the "v2" interface. If you prepare all of your SQL statements
3667 ** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead
3668 ** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
3669 ** then the more specific [error codes] are returned directly
3670 ** by sqlite3_step(). The use of the "v2" interface is recommended.
3671 */
3673 
3674 /*
3675 ** CAPI3REF: Number of columns in a result set
3676 **
3677 ** ^The sqlite3_data_count(P) interface returns the number of columns in the
3678 ** current row of the result set of [prepared statement] P.
3679 ** ^If prepared statement P does not have results ready to return
3680 ** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
3681 ** interfaces) then sqlite3_data_count(P) returns 0.
3682 ** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
3683 ** ^The sqlite3_data_count(P) routine returns 0 if the previous call to
3684 ** [sqlite3_step](P) returned [SQLITE_DONE]. ^The sqlite3_data_count(P)
3685 ** will return non-zero if previous call to [sqlite3_step](P) returned
3686 ** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]
3687 ** where it always returns zero since each step of that multi-step
3688 ** pragma returns 0 columns of data.
3689 **
3690 ** See also: [sqlite3_column_count()]
3691 */
3693 
3694 /*
3695 ** CAPI3REF: Fundamental Datatypes
3696 ** KEYWORDS: SQLITE_TEXT
3697 **
3698 ** ^(Every value in SQLite has one of five fundamental datatypes:
3699 **
3700 ** <ul>
3701 ** <li> 64-bit signed integer
3702 ** <li> 64-bit IEEE floating point number
3703 ** <li> string
3704 ** <li> BLOB
3705 ** <li> NULL
3706 ** </ul>)^
3707 **
3708 ** These constants are codes for each of those types.
3709 **
3710 ** Note that the SQLITE_TEXT constant was also used in SQLite version 2
3711 ** for a completely different meaning. Software that links against both
3712 ** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
3713 ** SQLITE_TEXT.
3714 */
3715 #define SQLITE_INTEGER 1
3716 #define SQLITE_FLOAT 2
3717 #define SQLITE_BLOB 4
3718 #define SQLITE_NULL 5
3719 #ifdef SQLITE_TEXT
3720 # undef SQLITE_TEXT
3721 #else
3722 # define SQLITE_TEXT 3
3723 #endif
3724 #define SQLITE3_TEXT 3
3725 
3726 /*
3727 ** CAPI3REF: Result Values From A Query
3728 ** KEYWORDS: {column access functions}
3729 **
3730 ** These routines form the "result set" interface.
3731 **
3732 ** ^These routines return information about a single column of the current
3733 ** result row of a query. ^In every case the first argument is a pointer
3734 ** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
3735 ** that was returned from [sqlite3_prepare_v2()] or one of its variants)
3736 ** and the second argument is the index of the column for which information
3737 ** should be returned. ^The leftmost column of the result set has the index 0.
3738 ** ^The number of columns in the result can be determined using
3739 ** [sqlite3_column_count()].
3740 **
3741 ** If the SQL statement does not currently point to a valid row, or if the
3742 ** column index is out of range, the result is undefined.
3743 ** These routines may only be called when the most recent call to
3744 ** [sqlite3_step()] has returned [SQLITE_ROW] and neither
3745 ** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
3746 ** If any of these routines are called after [sqlite3_reset()] or
3747 ** [sqlite3_finalize()] or after [sqlite3_step()] has returned
3748 ** something other than [SQLITE_ROW], the results are undefined.
3749 ** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
3750 ** are called from a different thread while any of these routines
3751 ** are pending, then the results are undefined.
3752 **
3753 ** ^The sqlite3_column_type() routine returns the
3754 ** [SQLITE_INTEGER | datatype code] for the initial data type
3755 ** of the result column. ^The returned value is one of [SQLITE_INTEGER],
3756 ** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL]. The value
3757 ** returned by sqlite3_column_type() is only meaningful if no type
3758 ** conversions have occurred as described below. After a type conversion,
3759 ** the value returned by sqlite3_column_type() is undefined. Future
3760 ** versions of SQLite may change the behavior of sqlite3_column_type()
3761 ** following a type conversion.
3762 **
3763 ** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
3764 ** routine returns the number of bytes in that BLOB or string.
3765 ** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts
3766 ** the string to UTF-8 and then returns the number of bytes.
3767 ** ^If the result is a numeric value then sqlite3_column_bytes() uses
3768 ** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
3769 ** the number of bytes in that string.
3770 ** ^If the result is NULL, then sqlite3_column_bytes() returns zero.
3771 **
3772 ** ^If the result is a BLOB or UTF-16 string then the sqlite3_column_bytes16()
3773 ** routine returns the number of bytes in that BLOB or string.
3774 ** ^If the result is a UTF-8 string, then sqlite3_column_bytes16() converts
3775 ** the string to UTF-16 and then returns the number of bytes.
3776 ** ^If the result is a numeric value then sqlite3_column_bytes16() uses
3777 ** [sqlite3_snprintf()] to convert that value to a UTF-16 string and returns
3778 ** the number of bytes in that string.
3779 ** ^If the result is NULL, then sqlite3_column_bytes16() returns zero.
3780 **
3781 ** ^The values returned by [sqlite3_column_bytes()] and
3782 ** [sqlite3_column_bytes16()] do not include the zero terminators at the end
3783 ** of the string. ^For clarity: the values returned by
3784 ** [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] are the number of
3785 ** bytes in the string, not the number of characters.
3786 **
3787 ** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
3788 ** even empty strings, are always zero-terminated. ^The return
3789 ** value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer.
3790 **
3791 ** ^The object returned by [sqlite3_column_value()] is an
3792 ** [unprotected sqlite3_value] object. An unprotected sqlite3_value object
3793 ** may only be used with [sqlite3_bind_value()] and [sqlite3_result_value()].
3794 ** If the [unprotected sqlite3_value] object returned by
3795 ** [sqlite3_column_value()] is used in any other way, including calls
3796 ** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
3797 ** or [sqlite3_value_bytes()], then the behavior is undefined.
3798 **
3799 ** These routines attempt to convert the value where appropriate. ^For
3800 ** example, if the internal representation is FLOAT and a text result
3801 ** is requested, [sqlite3_snprintf()] is used internally to perform the
3802 ** conversion automatically. ^(The following table details the conversions
3803 ** that are applied:
3804 **
3805 ** <blockquote>
3806 ** <table border="1">
3807 ** <tr><th> Internal<br>Type <th> Requested<br>Type <th> Conversion
3808 **
3809 ** <tr><td> NULL <td> INTEGER <td> Result is 0
3810 ** <tr><td> NULL <td> FLOAT <td> Result is 0.0
3811 ** <tr><td> NULL <td> TEXT <td> Result is a NULL pointer
3812 ** <tr><td> NULL <td> BLOB <td> Result is a NULL pointer
3813 ** <tr><td> INTEGER <td> FLOAT <td> Convert from integer to float
3814 ** <tr><td> INTEGER <td> TEXT <td> ASCII rendering of the integer
3815 ** <tr><td> INTEGER <td> BLOB <td> Same as INTEGER->TEXT
3816 ** <tr><td> FLOAT <td> INTEGER <td> [CAST] to INTEGER
3817 ** <tr><td> FLOAT <td> TEXT <td> ASCII rendering of the float
3818 ** <tr><td> FLOAT <td> BLOB <td> [CAST] to BLOB
3819 ** <tr><td> TEXT <td> INTEGER <td> [CAST] to INTEGER
3820 ** <tr><td> TEXT <td> FLOAT <td> [CAST] to REAL
3821 ** <tr><td> TEXT <td> BLOB <td> No change
3822 ** <tr><td> BLOB <td> INTEGER <td> [CAST] to INTEGER
3823 ** <tr><td> BLOB <td> FLOAT <td> [CAST] to REAL
3824 ** <tr><td> BLOB <td> TEXT <td> Add a zero terminator if needed
3825 ** </table>
3826 ** </blockquote>)^
3827 **
3828 ** The table above makes reference to standard C library functions atoi()
3829 ** and atof(). SQLite does not really use these functions. It has its
3830 ** own equivalent internal routines. The atoi() and atof() names are
3831 ** used in the table for brevity and because they are familiar to most
3832 ** C programmers.
3833 **
3834 ** Note that when type conversions occur, pointers returned by prior
3835 ** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
3836 ** sqlite3_column_text16() may be invalidated.
3837 ** Type conversions and pointer invalidations might occur
3838 ** in the following cases:
3839 **
3840 ** <ul>
3841 ** <li> The initial content is a BLOB and sqlite3_column_text() or
3842 ** sqlite3_column_text16() is called. A zero-terminator might
3843 ** need to be added to the string.</li>
3844 ** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
3845 ** sqlite3_column_text16() is called. The content must be converted
3846 ** to UTF-16.</li>
3847 ** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
3848 ** sqlite3_column_text() is called. The content must be converted
3849 ** to UTF-8.</li>
3850 ** </ul>
3851 **
3852 ** ^Conversions between UTF-16be and UTF-16le are always done in place and do
3853 ** not invalidate a prior pointer, though of course the content of the buffer
3854 ** that the prior pointer references will have been modified. Other kinds
3855 ** of conversion are done in place when it is possible, but sometimes they
3856 ** are not possible and in those cases prior pointers are invalidated.
3857 **
3858 ** The safest and easiest to remember policy is to invoke these routines
3859 ** in one of the following ways:
3860 **
3861 ** <ul>
3862 ** <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
3863 ** <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
3864 ** <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
3865 ** </ul>
3866 **
3867 ** In other words, you should call sqlite3_column_text(),
3868 ** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
3869 ** into the desired format, then invoke sqlite3_column_bytes() or
3870 ** sqlite3_column_bytes16() to find the size of the result. Do not mix calls
3871 ** to sqlite3_column_text() or sqlite3_column_blob() with calls to
3872 ** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
3873 ** with calls to sqlite3_column_bytes().
3874 **
3875 ** ^The pointers returned are valid until a type conversion occurs as
3876 ** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
3877 ** [sqlite3_finalize()] is called. ^The memory space used to hold strings
3878 ** and BLOBs is freed automatically. Do <b>not</b> pass the pointers returned
3879 ** from [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
3880 ** [sqlite3_free()].
3881 **
3882 ** ^(If a memory allocation error occurs during the evaluation of any
3883 ** of these routines, a default value is returned. The default value
3884 ** is either the integer 0, the floating point number 0.0, or a NULL
3885 ** pointer. Subsequent calls to [sqlite3_errcode()] will return
3886 ** [SQLITE_NOMEM].)^
3887 */
3888 SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt*, int iCol);
3891 SQLITE_API double sqlite3_column_double(sqlite3_stmt*, int iCol);
3893 SQLITE_API sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);
3894 SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol);
3895 SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt*, int iCol);
3898 
3899 /*
3900 ** CAPI3REF: Destroy A Prepared Statement Object
3901 **
3902 ** ^The sqlite3_finalize() function is called to delete a [prepared statement].
3903 ** ^If the most recent evaluation of the statement encountered no errors
3904 ** or if the statement is never been evaluated, then sqlite3_finalize() returns
3905 ** SQLITE_OK. ^If the most recent evaluation of statement S failed, then
3906 ** sqlite3_finalize(S) returns the appropriate [error code] or
3907 ** [extended error code].
3908 **
3909 ** ^The sqlite3_finalize(S) routine can be called at any point during
3910 ** the life cycle of [prepared statement] S:
3911 ** before statement S is ever evaluated, after
3912 ** one or more calls to [sqlite3_reset()], or after any call
3913 ** to [sqlite3_step()] regardless of whether or not the statement has
3914 ** completed execution.
3915 **
3916 ** ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op.
3917 **
3918 ** The application must finalize every [prepared statement] in order to avoid
3919 ** resource leaks. It is a grievous error for the application to try to use
3920 ** a prepared statement after it has been finalized. Any use of a prepared
3921 ** statement after it has been finalized can result in undefined and
3922 ** undesirable behavior such as segfaults and heap corruption.
3923 */
3925 
3926 /*
3927 ** CAPI3REF: Reset A Prepared Statement Object
3928 **
3929 ** The sqlite3_reset() function is called to reset a [prepared statement]
3930 ** object back to its initial state, ready to be re-executed.
3931 ** ^Any SQL statement variables that had values bound to them using
3932 ** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
3933 ** Use [sqlite3_clear_bindings()] to reset the bindings.
3934 **
3935 ** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S
3936 ** back to the beginning of its program.
3937 **
3938 ** ^If the most recent call to [sqlite3_step(S)] for the
3939 ** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
3940 ** or if [sqlite3_step(S)] has never before been called on S,
3941 ** then [sqlite3_reset(S)] returns [SQLITE_OK].
3942 **
3943 ** ^If the most recent call to [sqlite3_step(S)] for the
3944 ** [prepared statement] S indicated an error, then
3945 ** [sqlite3_reset(S)] returns an appropriate [error code].
3946 **
3947 ** ^The [sqlite3_reset(S)] interface does not change the values
3948 ** of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
3949 */
3951 
3952 /*
3953 ** CAPI3REF: Create Or Redefine SQL Functions
3954 ** KEYWORDS: {function creation routines}
3955 ** KEYWORDS: {application-defined SQL function}
3956 ** KEYWORDS: {application-defined SQL functions}
3957 **
3958 ** ^These functions (collectively known as "function creation routines")
3959 ** are used to add SQL functions or aggregates or to redefine the behavior
3960 ** of existing SQL functions or aggregates. The only differences between
3961 ** these routines are the text encoding expected for
3962 ** the second parameter (the name of the function being created)
3963 ** and the presence or absence of a destructor callback for
3964 ** the application data pointer.
3965 **
3966 ** ^The first parameter is the [database connection] to which the SQL
3967 ** function is to be added. ^If an application uses more than one database
3968 ** connection then application-defined SQL functions must be added
3969 ** to each database connection separately.
3970 **
3971 ** ^The second parameter is the name of the SQL function to be created or
3972 ** redefined. ^The length of the name is limited to 255 bytes in a UTF-8
3973 ** representation, exclusive of the zero-terminator. ^Note that the name
3974 ** length limit is in UTF-8 bytes, not characters nor UTF-16 bytes.
3975 ** ^Any attempt to create a function with a longer name
3976 ** will result in [SQLITE_MISUSE] being returned.
3977 **
3978 ** ^The third parameter (nArg)
3979 ** is the number of arguments that the SQL function or
3980 ** aggregate takes. ^If this parameter is -1, then the SQL function or
3981 ** aggregate may take any number of arguments between 0 and the limit
3982 ** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]). If the third
3983 ** parameter is less than -1 or greater than 127 then the behavior is
3984 ** undefined.
3985 **
3986 ** ^The fourth parameter, eTextRep, specifies what
3987 ** [SQLITE_UTF8 | text encoding] this SQL function prefers for
3988 ** its parameters. Every SQL function implementation must be able to work
3989 ** with UTF-8, UTF-16le, or UTF-16be. But some implementations may be
3990 ** more efficient with one encoding than another. ^An application may
3991 ** invoke sqlite3_create_function() or sqlite3_create_function16() multiple
3992 ** times with the same function but with different values of eTextRep.
3993 ** ^When multiple implementations of the same function are available, SQLite
3994 ** will pick the one that involves the least amount of data conversion.
3995 ** If there is only a single implementation which does not care what text
3996 ** encoding is used, then the fourth argument should be [SQLITE_ANY].
3997 **
3998 ** ^(The fifth parameter is an arbitrary pointer. The implementation of the
3999 ** function can gain access to this pointer using [sqlite3_user_data()].)^
4000 **
4001 ** ^The sixth, seventh and eighth parameters, xFunc, xStep and xFinal, are
4002 ** pointers to C-language functions that implement the SQL function or
4003 ** aggregate. ^A scalar SQL function requires an implementation of the xFunc
4004 ** callback only; NULL pointers must be passed as the xStep and xFinal
4005 ** parameters. ^An aggregate SQL function requires an implementation of xStep
4006 ** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
4007 ** SQL function or aggregate, pass NULL pointers for all three function
4008 ** callbacks.
4009 **
4010 ** ^(If the ninth parameter to sqlite3_create_function_v2() is not NULL,
4011 ** then it is destructor for the application data pointer.
4012 ** The destructor is invoked when the function is deleted, either by being
4013 ** overloaded or when the database connection closes.)^
4014 ** ^The destructor is also invoked if the call to
4015 ** sqlite3_create_function_v2() fails.
4016 ** ^When the destructor callback of the tenth parameter is invoked, it
4017 ** is passed a single argument which is a copy of the application data
4018 ** pointer which was the fifth parameter to sqlite3_create_function_v2().
4019 **
4020 ** ^It is permitted to register multiple implementations of the same
4021 ** functions with the same name but with either differing numbers of
4022 ** arguments or differing preferred text encodings. ^SQLite will use
4023 ** the implementation that most closely matches the way in which the
4024 ** SQL function is used. ^A function implementation with a non-negative
4025 ** nArg parameter is a better match than a function implementation with
4026 ** a negative nArg. ^A function where the preferred text encoding
4027 ** matches the database encoding is a better
4028 ** match than a function where the encoding is different.
4029 ** ^A function where the encoding difference is between UTF16le and UTF16be
4030 ** is a closer match than a function where the encoding difference is
4031 ** between UTF8 and UTF16.
4032 **
4033 ** ^Built-in functions may be overloaded by new application-defined functions.
4034 **
4035 ** ^An application-defined function is permitted to call other
4036 ** SQLite interfaces. However, such calls must not
4037 ** close the database connection nor finalize or reset the prepared
4038 ** statement in which the function is running.
4039 */
4041  sqlite3 *db,
4042  const char *zFunctionName,
4043  int nArg,
4044  int eTextRep,
4045  void *pApp,
4046  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
4047  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
4048  void (*xFinal)(sqlite3_context*)
4049 );
4051  sqlite3 *db,
4052  const void *zFunctionName,
4053  int nArg,
4054  int eTextRep,
4055  void *pApp,
4056  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
4057  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
4058  void (*xFinal)(sqlite3_context*)
4059 );
4061  sqlite3 *db,
4062  const char *zFunctionName,
4063  int nArg,
4064  int eTextRep,
4065  void *pApp,
4066  void (*xFunc)(sqlite3_context*,int,sqlite3_value**),
4067  void (*xStep)(sqlite3_context*,int,sqlite3_value**),
4068  void (*xFinal)(sqlite3_context*),
4069  void(*xDestroy)(void*)
4070 );
4071 
4072 /*
4073 ** CAPI3REF: Text Encodings
4074 **
4075 ** These constant define integer codes that represent the various
4076 ** text encodings supported by SQLite.
4077 */
4078 #define SQLITE_UTF8 1
4079 #define SQLITE_UTF16LE 2
4080 #define SQLITE_UTF16BE 3
4081 #define SQLITE_UTF16 4 /* Use native byte order */
4082 #define SQLITE_ANY 5 /* sqlite3_create_function only */
4083 #define SQLITE_UTF16_ALIGNED 8 /* sqlite3_create_collation only */
4084 
4085 /*
4086 ** CAPI3REF: Deprecated Functions
4087 ** DEPRECATED
4088 **
4089 ** These functions are [deprecated]. In order to maintain
4090 ** backwards compatibility with older code, these functions continue
4091 ** to be supported. However, new applications should avoid
4092 ** the use of these functions. To help encourage people to avoid
4093 ** using these functions, we are not going to tell you what they do.
4094 */
4095 #ifndef SQLITE_OMIT_DEPRECATED
4101 SQLITE_API SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),
4102  void*,sqlite3_int64);
4103 #endif
4104 
4105 /*
4106 ** CAPI3REF: Obtaining SQL Function Parameter Values
4107 **
4108 ** The C-language implementation of SQL functions and aggregates uses
4109 ** this set of interface routines to access the parameter values on
4110 ** the function or aggregate.
4111 **
4112 ** The xFunc (for scalar functions) or xStep (for aggregates) parameters
4113 ** to [sqlite3_create_function()] and [sqlite3_create_function16()]
4114 ** define callbacks that implement the SQL functions and aggregates.
4115 ** The 3rd parameter to these callbacks is an array of pointers to
4116 ** [protected sqlite3_value] objects. There is one [sqlite3_value] object for
4117 ** each parameter to the SQL function. These routines are used to
4118 ** extract values from the [sqlite3_value] objects.
4119 **
4120 ** These routines work only with [protected sqlite3_value] objects.
4121 ** Any attempt to use these routines on an [unprotected sqlite3_value]
4122 ** object results in undefined behavior.
4123 **
4124 ** ^These routines work just like the corresponding [column access functions]
4125 ** except that these routines take a single [protected sqlite3_value] object
4126 ** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
4127 **
4128 ** ^The sqlite3_value_text16() interface extracts a UTF-16 string
4129 ** in the native byte-order of the host machine. ^The
4130 ** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
4131 ** extract UTF-16 strings as big-endian and little-endian respectively.
4132 **
4133 ** ^(The sqlite3_value_numeric_type() interface attempts to apply
4134 ** numeric affinity to the value. This means that an attempt is
4135 ** made to convert the value to an integer or floating point. If
4136 ** such a conversion is possible without loss of information (in other
4137 ** words, if the value is a string that looks like a number)
4138 ** then the conversion is performed. Otherwise no conversion occurs.
4139 ** The [SQLITE_INTEGER | datatype] after conversion is returned.)^
4140 **
4141 ** Please pay particular attention to the fact that the pointer returned
4142 ** from [sqlite3_value_blob()], [sqlite3_value_text()], or
4143 ** [sqlite3_value_text16()] can be invalidated by a subsequent call to
4144 ** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
4145 ** or [sqlite3_value_text16()].
4146 **
4147 ** These routines must be called from the same thread as
4148 ** the SQL function that supplied the [sqlite3_value*] parameters.
4149 */
4156 SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value*);
4162 
4163 /*
4164 ** CAPI3REF: Obtain Aggregate Function Context
4165 **
4166 ** Implementations of aggregate SQL functions use this
4167 ** routine to allocate memory for storing their state.
4168 **
4169 ** ^The first time the sqlite3_aggregate_context(C,N) routine is called
4170 ** for a particular aggregate function, SQLite
4171 ** allocates N of memory, zeroes out that memory, and returns a pointer
4172 ** to the new memory. ^On second and subsequent calls to
4173 ** sqlite3_aggregate_context() for the same aggregate function instance,
4174 ** the same buffer is returned. Sqlite3_aggregate_context() is normally
4175 ** called once for each invocation of the xStep callback and then one
4176 ** last time when the xFinal callback is invoked. ^(When no rows match
4177 ** an aggregate query, the xStep() callback of the aggregate function
4178 ** implementation is never called and xFinal() is called exactly once.
4179 ** In those cases, sqlite3_aggregate_context() might be called for the
4180 ** first time from within xFinal().)^
4181 **
4182 ** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer
4183 ** when first called if N is less than or equal to zero or if a memory
4184 ** allocate error occurs.
4185 **
4186 ** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is
4187 ** determined by the N parameter on first successful call. Changing the
4188 ** value of N in subsequent call to sqlite3_aggregate_context() within
4189 ** the same aggregate function instance will not resize the memory
4190 ** allocation.)^ Within the xFinal callback, it is customary to set
4191 ** N=0 in calls to sqlite3_aggregate_context(C,N) so that no
4192 ** pointless memory allocations occur.
4193 **
4194 ** ^SQLite automatically frees the memory allocated by
4195 ** sqlite3_aggregate_context() when the aggregate query concludes.
4196 **
4197 ** The first parameter must be a copy of the
4198 ** [sqlite3_context | SQL function context] that is the first parameter
4199 ** to the xStep or xFinal callback routine that implements the aggregate
4200 ** function.
4201 **
4202 ** This routine must be called from the same thread in which
4203 ** the aggregate SQL function is running.
4204 */
4206 
4207 /*
4208 ** CAPI3REF: User Data For Functions
4209 **
4210 ** ^The sqlite3_user_data() interface returns a copy of
4211 ** the pointer that was the pUserData parameter (the 5th parameter)
4212 ** of the [sqlite3_create_function()]
4213 ** and [sqlite3_create_function16()] routines that originally
4214 ** registered the application defined function.
4215 **
4216 ** This routine must be called from the same thread in which
4217 ** the application-defined function is running.
4218 */
4220 
4221 /*
4222 ** CAPI3REF: Database Connection For Functions
4223 **
4224 ** ^The sqlite3_context_db_handle() interface returns a copy of
4225 ** the pointer to the [database connection] (the 1st parameter)
4226 ** of the [sqlite3_create_function()]
4227 ** and [sqlite3_create_function16()] routines that originally
4228 ** registered the application defined function.
4229 */
4231 
4232 /*
4233 ** CAPI3REF: Function Auxiliary Data
4234 **
4235 ** These functions may be used by (non-aggregate) SQL functions to
4236 ** associate metadata with argument values. If the same value is passed to
4237 ** multiple invocations of the same SQL function during query execution, under
4238 ** some circumstances the associated metadata may be preserved. An example
4239 ** of where this might be useful is in a regular-expression matching
4240 ** function. The compiled version of the regular expression can be stored as
4241 ** metadata associated with the pattern string.
4242 ** Then as long as the pattern string remains the same,
4243 ** the compiled regular expression can be reused on multiple
4244 ** invocations of the same function.
4245 **
4246 ** ^The sqlite3_get_auxdata() interface returns a pointer to the metadata
4247 ** associated by the sqlite3_set_auxdata() function with the Nth argument
4248 ** value to the application-defined function. ^If there is no metadata
4249 ** associated with the function argument, this sqlite3_get_auxdata() interface
4250 ** returns a NULL pointer.
4251 **
4252 ** ^The sqlite3_set_auxdata(C,N,P,X) interface saves P as metadata for the N-th
4253 ** argument of the application-defined function. ^Subsequent
4254 ** calls to sqlite3_get_auxdata(C,N) return P from the most recent
4255 ** sqlite3_set_auxdata(C,N,P,X) call if the metadata is still valid or
4256 ** NULL if the metadata has been discarded.
4257 ** ^After each call to sqlite3_set_auxdata(C,N,P,X) where X is not NULL,
4258 ** SQLite will invoke the destructor function X with parameter P exactly
4259 ** once, when the metadata is discarded.
4260 ** SQLite is free to discard the metadata at any time, including: <ul>
4261 ** <li> when the corresponding function parameter changes, or
4262 ** <li> when [sqlite3_reset()] or [sqlite3_finalize()] is called for the
4263 ** SQL statement, or
4264 ** <li> when sqlite3_set_auxdata() is invoked again on the same parameter, or
4265 ** <li> during the original sqlite3_set_auxdata() call when a memory
4266 ** allocation error occurs. </ul>)^
4267 **
4268 ** Note the last bullet in particular. The destructor X in
4269 ** sqlite3_set_auxdata(C,N,P,X) might be called immediately, before the
4270 ** sqlite3_set_auxdata() interface even returns. Hence sqlite3_set_auxdata()
4271 ** should be called near the end of the function implementation and the
4272 ** function implementation should not make any use of P after
4273 ** sqlite3_set_auxdata() has been called.
4274 **
4275 ** ^(In practice, metadata is preserved between function calls for
4276 ** function parameters that are compile-time constants, including literal
4277 ** values and [parameters] and expressions composed from the same.)^
4278 **
4279 ** These routines must be called from the same thread in which
4280 ** the SQL function is running.
4281 */
4283 SQLITE_API void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));
4284 
4285 
4286 /*
4287 ** CAPI3REF: Constants Defining Special Destructor Behavior
4288 **
4289 ** These are special values for the destructor that is passed in as the
4290 ** final argument to routines like [sqlite3_result_blob()]. ^If the destructor
4291 ** argument is SQLITE_STATIC, it means that the content pointer is constant
4292 ** and will never change. It does not need to be destroyed. ^The
4293 ** SQLITE_TRANSIENT value means that the content will likely change in
4294 ** the near future and that SQLite should make its own private copy of
4295 ** the content before returning.
4296 **
4297 ** The typedef is necessary to work around problems in certain
4298 ** C++ compilers.
4299 */
4300 typedef void (*sqlite3_destructor_type)(void*);
4301 #define SQLITE_STATIC ((sqlite3_destructor_type)0)
4302 #define SQLITE_TRANSIENT ((sqlite3_destructor_type)-1)
4303 
4304 /*
4305 ** CAPI3REF: Setting The Result Of An SQL Function
4306 **
4307 ** These routines are used by the xFunc or xFinal callbacks that
4308 ** implement SQL functions and aggregates. See
4309 ** [sqlite3_create_function()] and [sqlite3_create_function16()]
4310 ** for additional information.
4311 **
4312 ** These functions work very much like the [parameter binding] family of
4313 ** functions used to bind values to host parameters in prepared statements.
4314 ** Refer to the [SQL parameter] documentation for additional information.
4315 **
4316 ** ^The sqlite3_result_blob() interface sets the result from
4317 ** an application-defined function to be the BLOB whose content is pointed
4318 ** to by the second parameter and which is N bytes long where N is the
4319 ** third parameter.
4320 **
4321 ** ^The sqlite3_result_zeroblob() interfaces set the result of
4322 ** the application-defined function to be a BLOB containing all zero
4323 ** bytes and N bytes in size, where N is the value of the 2nd parameter.
4324 **
4325 ** ^The sqlite3_result_double() interface sets the result from
4326 ** an application-defined function to be a floating point value specified
4327 ** by its 2nd argument.
4328 **
4329 ** ^The sqlite3_result_error() and sqlite3_result_error16() functions
4330 ** cause the implemented SQL function to throw an exception.
4331 ** ^SQLite uses the string pointed to by the
4332 ** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
4333 ** as the text of an error message. ^SQLite interprets the error
4334 ** message string from sqlite3_result_error() as UTF-8. ^SQLite
4335 ** interprets the string from sqlite3_result_error16() as UTF-16 in native
4336 ** byte order. ^If the third parameter to sqlite3_result_error()
4337 ** or sqlite3_result_error16() is negative then SQLite takes as the error
4338 ** message all text up through the first zero character.
4339 ** ^If the third parameter to sqlite3_result_error() or
4340 ** sqlite3_result_error16() is non-negative then SQLite takes that many
4341 ** bytes (not characters) from the 2nd parameter as the error message.
4342 ** ^The sqlite3_result_error() and sqlite3_result_error16()
4343 ** routines make a private copy of the error message text before
4344 ** they return. Hence, the calling function can deallocate or
4345 ** modify the text after they return without harm.
4346 ** ^The sqlite3_result_error_code() function changes the error code
4347 ** returned by SQLite as a result of an error in a function. ^By default,
4348 ** the error code is SQLITE_ERROR. ^A subsequent call to sqlite3_result_error()
4349 ** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
4350 **
4351 ** ^The sqlite3_result_error_toobig() interface causes SQLite to throw an
4352 ** error indicating that a string or BLOB is too long to represent.
4353 **
4354 ** ^The sqlite3_result_error_nomem() interface causes SQLite to throw an
4355 ** error indicating that a memory allocation failed.
4356 **
4357 ** ^The sqlite3_result_int() interface sets the return value
4358 ** of the application-defined function to be the 32-bit signed integer
4359 ** value given in the 2nd argument.
4360 ** ^The sqlite3_result_int64() interface sets the return value
4361 ** of the application-defined function to be the 64-bit signed integer
4362 ** value given in the 2nd argument.
4363 **
4364 ** ^The sqlite3_result_null() interface sets the return value
4365 ** of the application-defined function to be NULL.
4366 **
4367 ** ^The sqlite3_result_text(), sqlite3_result_text16(),
4368 ** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
4369 ** set the return value of the application-defined function to be
4370 ** a text string which is represented as UTF-8, UTF-16 native byte order,
4371 ** UTF-16 little endian, or UTF-16 big endian, respectively.
4372 ** ^SQLite takes the text result from the application from
4373 ** the 2nd parameter of the sqlite3_result_text* interfaces.
4374 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
4375 ** is negative, then SQLite takes result text from the 2nd parameter
4376 ** through the first zero character.
4377 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
4378 ** is non-negative, then as many bytes (not characters) of the text
4379 ** pointed to by the 2nd parameter are taken as the application-defined
4380 ** function result. If the 3rd parameter is non-negative, then it
4381 ** must be the byte offset into the string where the NUL terminator would
4382 ** appear if the string where NUL terminated. If any NUL characters occur
4383 ** in the string at a byte offset that is less than the value of the 3rd
4384 ** parameter, then the resulting string will contain embedded NULs and the
4385 ** result of expressions operating on strings with embedded NULs is undefined.
4386 ** ^If the 4th parameter to the sqlite3_result_text* interfaces
4387 ** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
4388 ** function as the destructor on the text or BLOB result when it has
4389 ** finished using that result.
4390 ** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
4391 ** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
4392 ** assumes that the text or BLOB result is in constant space and does not
4393 ** copy the content of the parameter nor call a destructor on the content
4394 ** when it has finished using that result.
4395 ** ^If the 4th parameter to the sqlite3_result_text* interfaces
4396 ** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
4397 ** then SQLite makes a copy of the result into space obtained from
4398 ** from [sqlite3_malloc()] before it returns.
4399 **
4400 ** ^The sqlite3_result_value() interface sets the result of
4401 ** the application-defined function to be a copy the
4402 ** [unprotected sqlite3_value] object specified by the 2nd parameter. ^The
4403 ** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
4404 ** so that the [sqlite3_value] specified in the parameter may change or
4405 ** be deallocated after sqlite3_result_value() returns without harm.
4406 ** ^A [protected sqlite3_value] object may always be used where an
4407 ** [unprotected sqlite3_value] object is required, so either
4408 ** kind of [sqlite3_value] object can be used with this interface.
4409 **
4410 ** If these routines are called from within the different thread
4411 ** than the one containing the application-defined function that received
4412 ** the [sqlite3_context] pointer, the results are undefined.
4413 */
4414 SQLITE_API void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*));
4416 SQLITE_API void sqlite3_result_error(sqlite3_context*, const char*, int);
4417 SQLITE_API void sqlite3_result_error16(sqlite3_context*, const void*, int);
4422 SQLITE_API void sqlite3_result_int64(sqlite3_context*, sqlite3_int64);
4424 SQLITE_API void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*));
4425 SQLITE_API void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*));
4426 SQLITE_API void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*));
4427 SQLITE_API void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*));
4430 
4431 /*
4432 ** CAPI3REF: Define New Collating Sequences
4433 **
4434 ** ^These functions add, remove, or modify a [collation] associated
4435 ** with the [database connection] specified as the first argument.
4436 **
4437 ** ^The name of the collation is a UTF-8 string
4438 ** for sqlite3_create_collation() and sqlite3_create_collation_v2()
4439 ** and a UTF-16 string in native byte order for sqlite3_create_collation16().
4440 ** ^Collation names that compare equal according to [sqlite3_strnicmp()] are
4441 ** considered to be the same name.
4442 **
4443 ** ^(The third argument (eTextRep) must be one of the constants:
4444 ** <ul>
4445 ** <li> [SQLITE_UTF8],
4446 ** <li> [SQLITE_UTF16LE],
4447 ** <li> [SQLITE_UTF16BE],
4448 ** <li> [SQLITE_UTF16], or
4449 ** <li> [SQLITE_UTF16_ALIGNED].
4450 ** </ul>)^
4451 ** ^The eTextRep argument determines the encoding of strings passed
4452 ** to the collating function callback, xCallback.
4453 ** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep
4454 ** force strings to be UTF16 with native byte order.
4455 ** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin
4456 ** on an even byte address.
4457 **
4458 ** ^The fourth argument, pArg, is an application data pointer that is passed
4459 ** through as the first argument to the collating function callback.
4460 **
4461 ** ^The fifth argument, xCallback, is a pointer to the collating function.
4462 ** ^Multiple collating functions can be registered using the same name but
4463 ** with different eTextRep parameters and SQLite will use whichever
4464 ** function requires the least amount of data transformation.
4465 ** ^If the xCallback argument is NULL then the collating function is
4466 ** deleted. ^When all collating functions having the same name are deleted,
4467 ** that collation is no longer usable.
4468 **
4469 ** ^The collating function callback is invoked with a copy of the pArg
4470 ** application data pointer and with two strings in the encoding specified
4471 ** by the eTextRep argument. The collating function must return an
4472 ** integer that is negative, zero, or positive
4473 ** if the first string is less than, equal to, or greater than the second,
4474 ** respectively. A collating function must always return the same answer
4475 ** given the same inputs. If two or more collating functions are registered
4476 ** to the same collation name (using different eTextRep values) then all
4477 ** must give an equivalent answer when invoked with equivalent strings.
4478 ** The collating function must obey the following properties for all
4479 ** strings A, B, and C:
4480 **
4481 ** <ol>
4482 ** <li> If A==B then B==A.
4483 ** <li> If A==B and B==C then A==C.
4484 ** <li> If A&lt;B THEN B&gt;A.
4485 ** <li> If A&lt;B and B&lt;C then A&lt;C.
4486 ** </ol>
4487 **
4488 ** If a collating function fails any of the above constraints and that
4489 ** collating function is registered and used, then the behavior of SQLite
4490 ** is undefined.
4491 **
4492 ** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation()
4493 ** with the addition that the xDestroy callback is invoked on pArg when
4494 ** the collating function is deleted.
4495 ** ^Collating functions are deleted when they are overridden by later
4496 ** calls to the collation creation functions or when the
4497 ** [database connection] is closed using [sqlite3_close()].
4498 **
4499 ** ^The xDestroy callback is <u>not</u> called if the
4500 ** sqlite3_create_collation_v2() function fails. Applications that invoke
4501 ** sqlite3_create_collation_v2() with a non-NULL xDestroy argument should
4502 ** check the return code and dispose of the application data pointer
4503 ** themselves rather than expecting SQLite to deal with it for them.
4504 ** This is different from every other SQLite interface. The inconsistency
4505 ** is unfortunate but cannot be changed without breaking backwards
4506 ** compatibility.
4507 **
4508 ** See also: [sqlite3_collation_needed()] and [sqlite3_collation_needed16()].
4509 */
4511  sqlite3*,
4512  const char *zName,
4513  int eTextRep,
4514  void *pArg,
4515  int(*xCompare)(void*,int,const void*,int,const void*)
4516 );
4518  sqlite3*,
4519  const char *zName,
4520  int eTextRep,
4521  void *pArg,
4522  int(*xCompare)(void*,int,const void*,int,const void*),
4523  void(*xDestroy)(void*)
4524 );
4526  sqlite3*,
4527  const void *zName,
4528  int eTextRep,
4529  void *pArg,
4530  int(*xCompare)(void*,int,const void*,int,const void*)
4531 );
4532 
4533 /*
4534 ** CAPI3REF: Collation Needed Callbacks
4535 **
4536 ** ^To avoid having to register all collation sequences before a database
4537 ** can be used, a single callback function may be registered with the
4538 ** [database connection] to be invoked whenever an undefined collation
4539 ** sequence is required.
4540 **
4541 ** ^If the function is registered using the sqlite3_collation_needed() API,
4542 ** then it is passed the names of undefined collation sequences as strings
4543 ** encoded in UTF-8. ^If sqlite3_collation_needed16() is used,
4544 ** the names are passed as UTF-16 in machine native byte order.
4545 ** ^A call to either function replaces the existing collation-needed callback.
4546 **
4547 ** ^(When the callback is invoked, the first argument passed is a copy
4548 ** of the second argument to sqlite3_collation_needed() or
4549 ** sqlite3_collation_needed16(). The second argument is the database
4550 ** connection. The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
4551 ** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
4552 ** sequence function required. The fourth parameter is the name of the
4553 ** required collation sequence.)^
4554 **
4555 ** The callback function should register the desired collation using
4556 ** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
4557 ** [sqlite3_create_collation_v2()].
4558 */
4560  sqlite3*,
4561  void*,
4562  void(*)(void*,sqlite3*,int eTextRep,const char*)
4563 );
4565  sqlite3*,
4566  void*,
4567  void(*)(void*,sqlite3*,int eTextRep,const void*)
4568 );
4569 
4570 #ifdef SQLITE_HAS_CODEC
4571 /*
4572 ** Specify the key for an encrypted database. This routine should be
4573 ** called right after sqlite3_open().
4574 **
4575 ** The code to implement this API is not available in the public release
4576 ** of SQLite.
4577 */
4578 SQLITE_API int sqlite3_key(
4579  sqlite3 *db, /* Database to be rekeyed */
4580  const void *pKey, int nKey /* The key */
4581 );
4582 SQLITE_API int sqlite3_key_v2(
4583  sqlite3 *db, /* Database to be rekeyed */
4584  const char *zDbName, /* Name of the database */
4585  const void *pKey, int nKey /* The key */
4586 );
4587 
4588 /*
4589 ** Change the key on an open database. If the current database is not
4590 ** encrypted, this routine will encrypt it. If pNew==0 or nNew==0, the
4591 ** database is decrypted.
4592 **
4593 ** The code to implement this API is not available in the public release
4594 ** of SQLite.
4595 */
4596 SQLITE_API int sqlite3_rekey(
4597  sqlite3 *db, /* Database to be rekeyed */
4598  const void *pKey, int nKey /* The new key */
4599 );
4600 SQLITE_API int sqlite3_rekey_v2(
4601  sqlite3 *db, /* Database to be rekeyed */
4602  const char *zDbName, /* Name of the database */
4603  const void *pKey, int nKey /* The new key */
4604 );
4605 
4606 /*
4607 ** Specify the activation key for a SEE database. Unless
4608 ** activated, none of the SEE routines will work.
4609 */
4610 SQLITE_API void sqlite3_activate_see(
4611  const char *zPassPhrase /* Activation phrase */
4612 );
4613 #endif
4614 
4615 #ifdef SQLITE_ENABLE_CEROD
4616 /*
4617 ** Specify the activation key for a CEROD database. Unless
4618 ** activated, none of the CEROD routines will work.
4619 */
4620 SQLITE_API void sqlite3_activate_cerod(
4621  const char *zPassPhrase /* Activation phrase */
4622 );
4623 #endif
4624 
4625 /*
4626 ** CAPI3REF: Suspend Execution For A Short Time
4627 **
4628 ** The sqlite3_sleep() function causes the current thread to suspend execution
4629 ** for at least a number of milliseconds specified in its parameter.
4630 **
4631 ** If the operating system does not support sleep requests with
4632 ** millisecond time resolution, then the time will be rounded up to
4633 ** the nearest second. The number of milliseconds of sleep actually
4634 ** requested from the operating system is returned.
4635 **
4636 ** ^SQLite implements this interface by calling the xSleep()
4637 ** method of the default [sqlite3_vfs] object. If the xSleep() method
4638 ** of the default VFS is not implemented correctly, or not implemented at
4639 ** all, then the behavior of sqlite3_sleep() may deviate from the description
4640 ** in the previous paragraphs.
4641 */
4642 SQLITE_API int sqlite3_sleep(int);
4643 
4644 /*
4645 ** CAPI3REF: Name Of The Folder Holding Temporary Files
4646 **
4647 ** ^(If this global variable is made to point to a string which is
4648 ** the name of a folder (a.k.a. directory), then all temporary files
4649 ** created by SQLite when using a built-in [sqlite3_vfs | VFS]
4650 ** will be placed in that directory.)^ ^If this variable
4651 ** is a NULL pointer, then SQLite performs a search for an appropriate
4652 ** temporary file directory.
4653 **
4654 ** It is not safe to read or modify this variable in more than one
4655 ** thread at a time. It is not safe to read or modify this variable
4656 ** if a [database connection] is being used at the same time in a separate
4657 ** thread.
4658 ** It is intended that this variable be set once
4659 ** as part of process initialization and before any SQLite interface
4660 ** routines have been called and that this variable remain unchanged
4661 ** thereafter.
4662 **
4663 ** ^The [temp_store_directory pragma] may modify this variable and cause
4664 ** it to point to memory obtained from [sqlite3_malloc]. ^Furthermore,
4665 ** the [temp_store_directory pragma] always assumes that any string
4666 ** that this variable points to is held in memory obtained from
4667 ** [sqlite3_malloc] and the pragma may attempt to free that memory
4668 ** using [sqlite3_free].
4669 ** Hence, if this variable is modified directly, either it should be
4670 ** made NULL or made to point to memory obtained from [sqlite3_malloc]
4671 ** or else the use of the [temp_store_directory pragma] should be avoided.
4672 **
4673 ** <b>Note to Windows Runtime users:</b> The temporary directory must be set
4674 ** prior to calling [sqlite3_open] or [sqlite3_open_v2]. Otherwise, various
4675 ** features that require the use of temporary files may fail. Here is an
4676 ** example of how to do this using C++ with the Windows Runtime:
4677 **
4678 ** <blockquote><pre>
4679 ** LPCWSTR zPath = Windows::Storage::ApplicationData::Current->
4680 ** &nbsp; TemporaryFolder->Path->Data();
4681 ** char zPathBuf&#91;MAX_PATH + 1&#93;;
4682 ** memset(zPathBuf, 0, sizeof(zPathBuf));
4683 ** WideCharToMultiByte(CP_UTF8, 0, zPath, -1, zPathBuf, sizeof(zPathBuf),
4684 ** &nbsp; NULL, NULL);
4685 ** sqlite3_temp_directory = sqlite3_mprintf("%s", zPathBuf);
4686 ** </pre></blockquote>
4687 */
4689 
4690 /*
4691 ** CAPI3REF: Name Of The Folder Holding Database Files
4692 **
4693 ** ^(If this global variable is made to point to a string which is
4694 ** the name of a folder (a.k.a. directory), then all database files
4695 ** specified with a relative pathname and created or accessed by
4696 ** SQLite when using a built-in windows [sqlite3_vfs | VFS] will be assumed
4697 ** to be relative to that directory.)^ ^If this variable is a NULL
4698 ** pointer, then SQLite assumes that all database files specified
4699 ** with a relative pathname are relative to the current directory
4700 ** for the process. Only the windows VFS makes use of this global
4701 ** variable; it is ignored by the unix VFS.
4702 **
4703 ** Changing the value of this variable while a database connection is
4704 ** open can result in a corrupt database.
4705 **
4706 ** It is not safe to read or modify this variable in more than one
4707 ** thread at a time. It is not safe to read or modify this variable
4708 ** if a [database connection] is being used at the same time in a separate
4709 ** thread.
4710 ** It is intended that this variable be set once
4711 ** as part of process initialization and before any SQLite interface
4712 ** routines have been called and that this variable remain unchanged
4713 ** thereafter.
4714 **
4715 ** ^The [data_store_directory pragma] may modify this variable and cause
4716 ** it to point to memory obtained from [sqlite3_malloc]. ^Furthermore,
4717 ** the [data_store_directory pragma] always assumes that any string
4718 ** that this variable points to is held in memory obtained from
4719 ** [sqlite3_malloc] and the pragma may attempt to free that memory
4720 ** using [sqlite3_free].
4721 ** Hence, if this variable is modified directly, either it should be
4722 ** made NULL or made to point to memory obtained from [sqlite3_malloc]
4723 ** or else the use of the [data_store_directory pragma] should be avoided.
4724 */
4726 
4727 /*
4728 ** CAPI3REF: Test For Auto-Commit Mode
4729 ** KEYWORDS: {autocommit mode}
4730 **
4731 ** ^The sqlite3_get_autocommit() interface returns non-zero or
4732 ** zero if the given database connection is or is not in autocommit mode,
4733 ** respectively. ^Autocommit mode is on by default.
4734 ** ^Autocommit mode is disabled by a [BEGIN] statement.
4735 ** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
4736 **
4737 ** If certain kinds of errors occur on a statement within a multi-statement
4738 ** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
4739 ** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the
4740 ** transaction might be rolled back automatically. The only way to
4741 ** find out whether SQLite automatically rolled back the transaction after
4742 ** an error is to use this function.
4743 **
4744 ** If another thread changes the autocommit status of the database
4745 ** connection while this routine is running, then the return value
4746 ** is undefined.
4747 */
4749 
4750 /*
4751 ** CAPI3REF: Find The Database Handle Of A Prepared Statement
4752 **
4753 ** ^The sqlite3_db_handle interface returns the [database connection] handle
4754 ** to which a [prepared statement] belongs. ^The [database connection]
4755 ** returned by sqlite3_db_handle is the same [database connection]
4756 ** that was the first argument
4757 ** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
4758 ** create the statement in the first place.
4759 */
4761 
4762 /*
4763 ** CAPI3REF: Return The Filename For A Database Connection
4764 **
4765 ** ^The sqlite3_db_filename(D,N) interface returns a pointer to a filename
4766 ** associated with database N of connection D. ^The main database file
4767 ** has the name "main". If there is no attached database N on the database
4768 ** connection D, or if database N is a temporary or in-memory database, then
4769 ** a NULL pointer is returned.
4770 **
4771 ** ^The filename returned by this function is the output of the
4772 ** xFullPathname method of the [VFS]. ^In other words, the filename
4773 ** will be an absolute pathname, even if the filename used
4774 ** to open the database originally was a URI or relative pathname.
4775 */
4776 SQLITE_API const char *sqlite3_db_filename(sqlite3 *db, const char *zDbName);
4777 
4778 /*
4779 ** CAPI3REF: Determine if a database is read-only
4780 **
4781 ** ^The sqlite3_db_readonly(D,N) interface returns 1 if the database N
4782 ** of connection D is read-only, 0 if it is read/write, or -1 if N is not
4783 ** the name of a database on connection D.
4784 */
4785 SQLITE_API int sqlite3_db_readonly(sqlite3 *db, const char *zDbName);
4786 
4787 /*
4788 ** CAPI3REF: Find the next prepared statement
4789 **
4790 ** ^This interface returns a pointer to the next [prepared statement] after
4791 ** pStmt associated with the [database connection] pDb. ^If pStmt is NULL
4792 ** then this interface returns a pointer to the first prepared statement
4793 ** associated with the database connection pDb. ^If no prepared statement
4794 ** satisfies the conditions of this routine, it returns NULL.
4795 **
4796 ** The [database connection] pointer D in a call to
4797 ** [sqlite3_next_stmt(D,S)] must refer to an open database
4798 ** connection and in particular must not be a NULL pointer.
4799 */
4801 
4802 /*
4803 ** CAPI3REF: Commit And Rollback Notification Callbacks
4804 **
4805 ** ^The sqlite3_commit_hook() interface registers a callback
4806 ** function to be invoked whenever a transaction is [COMMIT | committed].
4807 ** ^Any callback set by a previous call to sqlite3_commit_hook()
4808 ** for the same database connection is overridden.
4809 ** ^The sqlite3_rollback_hook() interface registers a callback
4810 ** function to be invoked whenever a transaction is [ROLLBACK | rolled back].
4811 ** ^Any callback set by a previous call to sqlite3_rollback_hook()
4812 ** for the same database connection is overridden.
4813 ** ^The pArg argument is passed through to the callback.
4814 ** ^If the callback on a commit hook function returns non-zero,
4815 ** then the commit is converted into a rollback.
4816 **
4817 ** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions
4818 ** return the P argument from the previous call of the same function
4819 ** on the same [database connection] D, or NULL for
4820 ** the first call for each function on D.
4821 **
4822 ** The commit and rollback hook callbacks are not reentrant.
4823 ** The callback implementation must not do anything that will modify
4824 ** the database connection that invoked the callback. Any actions
4825 ** to modify the database connection must be deferred until after the
4826 ** completion of the [sqlite3_step()] call that triggered the commit
4827 ** or rollback hook in the first place.
4828 ** Note that running any other SQL statements, including SELECT statements,
4829 ** or merely calling [sqlite3_prepare_v2()] and [sqlite3_step()] will modify
4830 ** the database connections for the meaning of "modify" in this paragraph.
4831 **
4832 ** ^Registering a NULL function disables the callback.
4833 **
4834 ** ^When the commit hook callback routine returns zero, the [COMMIT]
4835 ** operation is allowed to continue normally. ^If the commit hook
4836 ** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].
4837 ** ^The rollback hook is invoked on a rollback that results from a commit
4838 ** hook returning non-zero, just as it would be with any other rollback.
4839 **
4840 ** ^For the purposes of this API, a transaction is said to have been
4841 ** rolled back if an explicit "ROLLBACK" statement is executed, or
4842 ** an error or constraint causes an implicit rollback to occur.
4843 ** ^The rollback callback is not invoked if a transaction is
4844 ** automatically rolled back because the database connection is closed.
4845 **
4846 ** See also the [sqlite3_update_hook()] interface.
4847 */
4848 SQLITE_API void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
4849 SQLITE_API void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
4850 
4851 /*
4852 ** CAPI3REF: Data Change Notification Callbacks
4853 **
4854 ** ^The sqlite3_update_hook() interface registers a callback function
4855 ** with the [database connection] identified by the first argument
4856 ** to be invoked whenever a row is updated, inserted or deleted in
4857 ** a rowid table.
4858 ** ^Any callback set by a previous call to this function
4859 ** for the same database connection is overridden.
4860 **
4861 ** ^The second argument is a pointer to the function to invoke when a
4862 ** row is updated, inserted or deleted in a rowid table.
4863 ** ^The first argument to the callback is a copy of the third argument
4864 ** to sqlite3_update_hook().
4865 ** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
4866 ** or [SQLITE_UPDATE], depending on the operation that caused the callback
4867 ** to be invoked.
4868 ** ^The third and fourth arguments to the callback contain pointers to the
4869 ** database and table name containing the affected row.
4870 ** ^The final callback parameter is the [rowid] of the row.
4871 ** ^In the case of an update, this is the [rowid] after the update takes place.
4872 **
4873 ** ^(The update hook is not invoked when internal system tables are
4874 ** modified (i.e. sqlite_master and sqlite_sequence).)^
4875 ** ^The update hook is not invoked when [WITHOUT ROWID] tables are modified.
4876 **
4877 ** ^In the current implementation, the update hook
4878 ** is not invoked when duplication rows are deleted because of an
4879 ** [ON CONFLICT | ON CONFLICT REPLACE] clause. ^Nor is the update hook
4880 ** invoked when rows are deleted using the [truncate optimization].
4881 ** The exceptions defined in this paragraph might change in a future
4882 ** release of SQLite.
4883 **
4884 ** The update hook implementation must not do anything that will modify
4885 ** the database connection that invoked the update hook. Any actions
4886 ** to modify the database connection must be deferred until after the
4887 ** completion of the [sqlite3_step()] call that triggered the update hook.
4888 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
4889 ** database connections for the meaning of "modify" in this paragraph.
4890 **
4891 ** ^The sqlite3_update_hook(D,C,P) function
4892 ** returns the P argument from the previous call
4893 ** on the same [database connection] D, or NULL for
4894 ** the first call on D.
4895 **
4896 ** See also the [sqlite3_commit_hook()] and [sqlite3_rollback_hook()]
4897 ** interfaces.
4898 */
4900  sqlite3*,
4901  void(*)(void *,int ,char const *,char const *,sqlite3_int64),
4902  void*
4903 );
4904 
4905 /*
4906 ** CAPI3REF: Enable Or Disable Shared Pager Cache
4907 **
4908 ** ^(This routine enables or disables the sharing of the database cache
4909 ** and schema data structures between [database connection | connections]
4910 ** to the same database. Sharing is enabled if the argument is true
4911 ** and disabled if the argument is false.)^
4912 **
4913 ** ^Cache sharing is enabled and disabled for an entire process.
4914 ** This is a change as of SQLite version 3.5.0. In prior versions of SQLite,
4915 ** sharing was enabled or disabled for each thread separately.
4916 **
4917 ** ^(The cache sharing mode set by this interface effects all subsequent
4918 ** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
4919 ** Existing database connections continue use the sharing mode
4920 ** that was in effect at the time they were opened.)^
4921 **
4922 ** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
4923 ** successfully. An [error code] is returned otherwise.)^
4924 **
4925 ** ^Shared cache is disabled by default. But this might change in
4926 ** future releases of SQLite. Applications that care about shared
4927 ** cache setting should set it explicitly.
4928 **
4929 ** This interface is threadsafe on processors where writing a
4930 ** 32-bit integer is atomic.
4931 **
4932 ** See Also: [SQLite Shared-Cache Mode]
4933 */
4935 
4936 /*
4937 ** CAPI3REF: Attempt To Free Heap Memory
4938 **
4939 ** ^The sqlite3_release_memory() interface attempts to free N bytes
4940 ** of heap memory by deallocating non-essential memory allocations
4941 ** held by the database library. Memory used to cache database
4942 ** pages to improve performance is an example of non-essential memory.
4943 ** ^sqlite3_release_memory() returns the number of bytes actually freed,
4944 ** which might be more or less than the amount requested.
4945 ** ^The sqlite3_release_memory() routine is a no-op returning zero
4946 ** if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT].
4947 **
4948 ** See also: [sqlite3_db_release_memory()]
4949 */
4951 
4952 /*
4953 ** CAPI3REF: Free Memory Used By A Database Connection
4954 **
4955 ** ^The sqlite3_db_release_memory(D) interface attempts to free as much heap
4956 ** memory as possible from database connection D. Unlike the
4957 ** [sqlite3_release_memory()] interface, this interface is in effect even
4958 ** when the [SQLITE_ENABLE_MEMORY_MANAGEMENT] compile-time option is
4959 ** omitted.
4960 **
4961 ** See also: [sqlite3_release_memory()]
4962 */
4964 
4965 /*
4966 ** CAPI3REF: Impose A Limit On Heap Size
4967 **
4968 ** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the
4969 ** soft limit on the amount of heap memory that may be allocated by SQLite.
4970 ** ^SQLite strives to keep heap memory utilization below the soft heap
4971 ** limit by reducing the number of pages held in the page cache
4972 ** as heap memory usages approaches the limit.
4973 ** ^The soft heap limit is "soft" because even though SQLite strives to stay
4974 ** below the limit, it will exceed the limit rather than generate
4975 ** an [SQLITE_NOMEM] error. In other words, the soft heap limit
4976 ** is advisory only.
4977 **
4978 ** ^The return value from sqlite3_soft_heap_limit64() is the size of
4979 ** the soft heap limit prior to the call, or negative in the case of an
4980 ** error. ^If the argument N is negative
4981 ** then no change is made to the soft heap limit. Hence, the current
4982 ** size of the soft heap limit can be determined by invoking
4983 ** sqlite3_soft_heap_limit64() with a negative argument.
4984 **
4985 ** ^If the argument N is zero then the soft heap limit is disabled.
4986 **
4987 ** ^(The soft heap limit is not enforced in the current implementation
4988 ** if one or more of following conditions are true:
4989 **
4990 ** <ul>
4991 ** <li> The soft heap limit is set to zero.
4992 ** <li> Memory accounting is disabled using a combination of the
4993 ** [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
4994 ** the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
4995 ** <li> An alternative page cache implementation is specified using
4996 ** [sqlite3_config]([SQLITE_CONFIG_PCACHE2],...).
4997 ** <li> The page cache allocates from its own memory pool supplied
4998 ** by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than
4999 ** from the heap.
5000 ** </ul>)^
5001 **
5002 ** Beginning with SQLite version 3.7.3, the soft heap limit is enforced
5003 ** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]
5004 ** compile-time option is invoked. With [SQLITE_ENABLE_MEMORY_MANAGEMENT],
5005 ** the soft heap limit is enforced on every memory allocation. Without
5006 ** [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced
5007 ** when memory is allocated by the page cache. Testing suggests that because
5008 ** the page cache is the predominate memory user in SQLite, most
5009 ** applications will achieve adequate soft heap limit enforcement without
5010 ** the use of [SQLITE_ENABLE_MEMORY_MANAGEMENT].
5011 **
5012 ** The circumstances under which SQLite will enforce the soft heap limit may
5013 ** changes in future releases of SQLite.
5014 */
5015 SQLITE_API sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 N);
5016 
5017 /*
5018 ** CAPI3REF: Deprecated Soft Heap Limit Interface
5019 ** DEPRECATED
5020 **
5021 ** This is a deprecated version of the [sqlite3_soft_heap_limit64()]
5022 ** interface. This routine is provided for historical compatibility
5023 ** only. All new applications should use the
5024 ** [sqlite3_soft_heap_limit64()] interface rather than this one.
5025 */
5027 
5028 
5029 /*
5030 ** CAPI3REF: Extract Metadata About A Column Of A Table
5031 **
5032 ** ^This routine returns metadata about a specific column of a specific
5033 ** database table accessible using the [database connection] handle
5034 ** passed as the first function argument.
5035 **
5036 ** ^The column is identified by the second, third and fourth parameters to
5037 ** this function. ^The second parameter is either the name of the database
5038 ** (i.e. "main", "temp", or an attached database) containing the specified
5039 ** table or NULL. ^If it is NULL, then all attached databases are searched
5040 ** for the table using the same algorithm used by the database engine to
5041 ** resolve unqualified table references.
5042 **
5043 ** ^The third and fourth parameters to this function are the table and column
5044 ** name of the desired column, respectively. Neither of these parameters
5045 ** may be NULL.
5046 **
5047 ** ^Metadata is returned by writing to the memory locations passed as the 5th
5048 ** and subsequent parameters to this function. ^Any of these arguments may be
5049 ** NULL, in which case the corresponding element of metadata is omitted.
5050 **
5051 ** ^(<blockquote>
5052 ** <table border="1">
5053 ** <tr><th> Parameter <th> Output<br>Type <th> Description
5054 **
5055 ** <tr><td> 5th <td> const char* <td> Data type
5056 ** <tr><td> 6th <td> const char* <td> Name of default collation sequence
5057 ** <tr><td> 7th <td> int <td> True if column has a NOT NULL constraint
5058 ** <tr><td> 8th <td> int <td> True if column is part of the PRIMARY KEY
5059 ** <tr><td> 9th <td> int <td> True if column is [AUTOINCREMENT]
5060 ** </table>
5061 ** </blockquote>)^
5062 **
5063 ** ^The memory pointed to by the character pointers returned for the
5064 ** declaration type and collation sequence is valid only until the next
5065 ** call to any SQLite API function.
5066 **
5067 ** ^If the specified table is actually a view, an [error code] is returned.
5068 **
5069 ** ^If the specified column is "rowid", "oid" or "_rowid_" and an
5070 ** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
5071 ** parameters are set for the explicitly declared column. ^(If there is no
5072 ** explicitly declared [INTEGER PRIMARY KEY] column, then the output
5073 ** parameters are set as follows:
5074 **
5075 ** <pre>
5076 ** data type: "INTEGER"
5077 ** collation sequence: "BINARY"
5078 ** not null: 0
5079 ** primary key: 1
5080 ** auto increment: 0
5081 ** </pre>)^
5082 **
5083 ** ^(This function may load one or more schemas from database files. If an
5084 ** error occurs during this process, or if the requested table or column
5085 ** cannot be found, an [error code] is returned and an error message left
5086 ** in the [database connection] (to be retrieved using sqlite3_errmsg()).)^
5087 **
5088 ** ^This API is only available if the library was compiled with the
5089 ** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol defined.
5090 */
5092  sqlite3 *db, /* Connection handle */
5093  const char *zDbName, /* Database name or NULL */
5094  const char *zTableName, /* Table name */
5095  const char *zColumnName, /* Column name */
5096  char const **pzDataType, /* OUTPUT: Declared data type */
5097  char const **pzCollSeq, /* OUTPUT: Collation sequence name */
5098  int *pNotNull, /* OUTPUT: True if NOT NULL constraint exists */
5099  int *pPrimaryKey, /* OUTPUT: True if column part of PK */
5100  int *pAutoinc /* OUTPUT: True if column is auto-increment */
5101 );
5102 
5103 /*
5104 ** CAPI3REF: Load An Extension
5105 **
5106 ** ^This interface loads an SQLite extension library from the named file.
5107 **
5108 ** ^The sqlite3_load_extension() interface attempts to load an
5109 ** [SQLite extension] library contained in the file zFile. If
5110 ** the file cannot be loaded directly, attempts are made to load
5111 ** with various operating-system specific extensions added.
5112 ** So for example, if "samplelib" cannot be loaded, then names like
5113 ** "samplelib.so" or "samplelib.dylib" or "samplelib.dll" might
5114 ** be tried also.
5115 **
5116 ** ^The entry point is zProc.
5117 ** ^(zProc may be 0, in which case SQLite will try to come up with an
5118 ** entry point name on its own. It first tries "sqlite3_extension_init".
5119 ** If that does not work, it constructs a name "sqlite3_X_init" where the
5120 ** X is consists of the lower-case equivalent of all ASCII alphabetic
5121 ** characters in the filename from the last "/" to the first following
5122 ** "." and omitting any initial "lib".)^
5123 ** ^The sqlite3_load_extension() interface returns
5124 ** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
5125 ** ^If an error occurs and pzErrMsg is not 0, then the
5126 ** [sqlite3_load_extension()] interface shall attempt to
5127 ** fill *pzErrMsg with error message text stored in memory
5128 ** obtained from [sqlite3_malloc()]. The calling function
5129 ** should free this memory by calling [sqlite3_free()].
5130 **
5131 ** ^Extension loading must be enabled using
5132 ** [sqlite3_enable_load_extension()] prior to calling this API,
5133 ** otherwise an error will be returned.
5134 **
5135 ** See also the [load_extension() SQL function].
5136 */
5138  sqlite3 *db, /* Load the extension into this database connection */
5139  const char *zFile, /* Name of the shared library containing extension */
5140  const char *zProc, /* Entry point. Derived from zFile if 0 */
5141  char **pzErrMsg /* Put error message here if not 0 */
5142 );
5143 
5144 /*
5145 ** CAPI3REF: Enable Or Disable Extension Loading
5146 **
5147 ** ^So as not to open security holes in older applications that are
5148 ** unprepared to deal with [extension loading], and as a means of disabling
5149 ** [extension loading] while evaluating user-entered SQL, the following API
5150 ** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
5151 **
5152 ** ^Extension loading is off by default.
5153 ** ^Call the sqlite3_enable_load_extension() routine with onoff==1
5154 ** to turn extension loading on and call it with onoff==0 to turn
5155 ** it back off again.
5156 */
5158 
5159 /*
5160 ** CAPI3REF: Automatically Load Statically Linked Extensions
5161 **
5162 ** ^This interface causes the xEntryPoint() function to be invoked for
5163 ** each new [database connection] that is created. The idea here is that
5164 ** xEntryPoint() is the entry point for a statically linked [SQLite extension]
5165 ** that is to be automatically loaded into all new database connections.
5166 **
5167 ** ^(Even though the function prototype shows that xEntryPoint() takes
5168 ** no arguments and returns void, SQLite invokes xEntryPoint() with three
5169 ** arguments and expects and integer result as if the signature of the
5170 ** entry point where as follows:
5171 **
5172 ** <blockquote><pre>
5173 ** &nbsp; int xEntryPoint(
5174 ** &nbsp; sqlite3 *db,
5175 ** &nbsp; const char **pzErrMsg,
5176 ** &nbsp; const struct sqlite3_api_routines *pThunk
5177 ** &nbsp; );
5178 ** </pre></blockquote>)^
5179 **
5180 ** If the xEntryPoint routine encounters an error, it should make *pzErrMsg
5181 ** point to an appropriate error message (obtained from [sqlite3_mprintf()])
5182 ** and return an appropriate [error code]. ^SQLite ensures that *pzErrMsg
5183 ** is NULL before calling the xEntryPoint(). ^SQLite will invoke
5184 ** [sqlite3_free()] on *pzErrMsg after xEntryPoint() returns. ^If any
5185 ** xEntryPoint() returns an error, the [sqlite3_open()], [sqlite3_open16()],
5186 ** or [sqlite3_open_v2()] call that provoked the xEntryPoint() will fail.
5187 **
5188 ** ^Calling sqlite3_auto_extension(X) with an entry point X that is already
5189 ** on the list of automatic extensions is a harmless no-op. ^No entry point
5190 ** will be called more than once for each database connection that is opened.
5191 **
5192 ** See also: [sqlite3_reset_auto_extension()]
5193 ** and [sqlite3_cancel_auto_extension()]
5194 */
5195 SQLITE_API int sqlite3_auto_extension(void (*xEntryPoint)(void));
5196 
5197 /*
5198 ** CAPI3REF: Cancel Automatic Extension Loading
5199 **
5200 ** ^The [sqlite3_cancel_auto_extension(X)] interface unregisters the
5201 ** initialization routine X that was registered using a prior call to
5202 ** [sqlite3_auto_extension(X)]. ^The [sqlite3_cancel_auto_extension(X)]
5203 ** routine returns 1 if initialization routine X was successfully
5204 ** unregistered and it returns 0 if X was not on the list of initialization
5205 ** routines.
5206 */
5207 SQLITE_API int sqlite3_cancel_auto_extension(void (*xEntryPoint)(void));
5208 
5209 /*
5210 ** CAPI3REF: Reset Automatic Extension Loading
5211 **
5212 ** ^This interface disables all automatic extensions previously
5213 ** registered using [sqlite3_auto_extension()].
5214 */
5216 
5217 /*
5218 ** The interface to the virtual-table mechanism is currently considered
5219 ** to be experimental. The interface might change in incompatible ways.
5220 ** If this is a problem for you, do not use the interface at this time.
5221 **
5222 ** When the virtual-table mechanism stabilizes, we will declare the
5223 ** interface fixed, support it indefinitely, and remove this comment.
5224 */
5225 
5226 /*
5227 ** Structures used by the virtual table interface
5228 */
5233 
5234 /*
5235 ** CAPI3REF: Virtual Table Object
5236 ** KEYWORDS: sqlite3_module {virtual table module}
5237 **
5238 ** This structure, sometimes called a "virtual table module",
5239 ** defines the implementation of a [virtual tables].
5240 ** This structure consists mostly of methods for the module.
5241 **
5242 ** ^A virtual table module is created by filling in a persistent
5243 ** instance of this structure and passing a pointer to that instance
5244 ** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].
5245 ** ^The registration remains valid until it is replaced by a different
5246 ** module or until the [database connection] closes. The content
5247 ** of this structure must not change while it is registered with
5248 ** any database connection.
5249 */
5252  int (*xCreate)(sqlite3*, void *pAux,
5253  int argc, const char *const*argv,
5254  sqlite3_vtab **ppVTab, char**);
5255  int (*xConnect)(sqlite3*, void *pAux,
5256  int argc, const char *const*argv,
5257  sqlite3_vtab **ppVTab, char**);
5258  int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*);
5259  int (*xDisconnect)(sqlite3_vtab *pVTab);
5260  int (*xDestroy)(sqlite3_vtab *pVTab);
5261  int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor);
5262  int (*xClose)(sqlite3_vtab_cursor*);
5263  int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr,
5264  int argc, sqlite3_value **argv);
5265  int (*xNext)(sqlite3_vtab_cursor*);
5266  int (*xEof)(sqlite3_vtab_cursor*);
5267  int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int);
5268  int (*xRowid)(sqlite3_vtab_cursor*, sqlite3_int64 *pRowid);
5269  int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite3_int64 *);
5270  int (*xBegin)(sqlite3_vtab *pVTab);
5271  int (*xSync)(sqlite3_vtab *pVTab);
5272  int (*xCommit)(sqlite3_vtab *pVTab);
5273  int (*xRollback)(sqlite3_vtab *pVTab);
5274  int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName,
5275  void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
5276  void **ppArg);
5277  int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
5278  /* The methods above are in version 1 of the sqlite_module object. Those
5279  ** below are for version 2 and greater. */
5280  int (*xSavepoint)(sqlite3_vtab *pVTab, int);
5281  int (*xRelease)(sqlite3_vtab *pVTab, int);
5282  int (*xRollbackTo)(sqlite3_vtab *pVTab, int);
5283 };
5284 
5285 /*
5286 ** CAPI3REF: Virtual Table Indexing Information
5287 ** KEYWORDS: sqlite3_index_info
5288 **
5289 ** The sqlite3_index_info structure and its substructures is used as part
5290 ** of the [virtual table] interface to
5291 ** pass information into and receive the reply from the [xBestIndex]
5292 ** method of a [virtual table module]. The fields under **Inputs** are the
5293 ** inputs to xBestIndex and are read-only. xBestIndex inserts its
5294 ** results into the **Outputs** fields.
5295 **
5296 ** ^(The aConstraint[] array records WHERE clause constraints of the form:
5297 **
5298 ** <blockquote>column OP expr</blockquote>
5299 **
5300 ** where OP is =, &lt;, &lt;=, &gt;, or &gt;=.)^ ^(The particular operator is
5301 ** stored in aConstraint[].op using one of the
5302 ** [SQLITE_INDEX_CONSTRAINT_EQ | SQLITE_INDEX_CONSTRAINT_ values].)^
5303 ** ^(The index of the column is stored in
5304 ** aConstraint[].iColumn.)^ ^(aConstraint[].usable is TRUE if the
5305 ** expr on the right-hand side can be evaluated (and thus the constraint
5306 ** is usable) and false if it cannot.)^
5307 **
5308 ** ^The optimizer automatically inverts terms of the form "expr OP column"
5309 ** and makes other simplifications to the WHERE clause in an attempt to
5310 ** get as many WHERE clause terms into the form shown above as possible.
5311 ** ^The aConstraint[] array only reports WHERE clause terms that are
5312 ** relevant to the particular virtual table being queried.
5313 **
5314 ** ^Information about the ORDER BY clause is stored in aOrderBy[].
5315 ** ^Each term of aOrderBy records a column of the ORDER BY clause.
5316 **
5317 ** The [xBestIndex] method must fill aConstraintUsage[] with information
5318 ** about what parameters to pass to xFilter. ^If argvIndex>0 then
5319 ** the right-hand side of the corresponding aConstraint[] is evaluated
5320 ** and becomes the argvIndex-th entry in argv. ^(If aConstraintUsage[].omit
5321 ** is true, then the constraint is assumed to be fully handled by the
5322 ** virtual table and is not checked again by SQLite.)^
5323 **
5324 ** ^The idxNum and idxPtr values are recorded and passed into the
5325 ** [xFilter] method.
5326 ** ^[sqlite3_free()] is used to free idxPtr if and only if
5327 ** needToFreeIdxPtr is true.
5328 **
5329 ** ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in
5330 ** the correct order to satisfy the ORDER BY clause so that no separate
5331 ** sorting step is required.
5332 **
5333 ** ^The estimatedCost value is an estimate of the cost of a particular
5334 ** strategy. A cost of N indicates that the cost of the strategy is similar
5335 ** to a linear scan of an SQLite table with N rows. A cost of log(N)
5336 ** indicates that the expense of the operation is similar to that of a
5337 ** binary search on a unique indexed field of an SQLite table with N rows.
5338 **
5339 ** ^The estimatedRows value is an estimate of the number of rows that
5340 ** will be returned by the strategy.
5341 **
5342 ** IMPORTANT: The estimatedRows field was added to the sqlite3_index_info
5343 ** structure for SQLite version 3.8.2. If a virtual table extension is
5344 ** used with an SQLite version earlier than 3.8.2, the results of attempting
5345 ** to read or write the estimatedRows field are undefined (but are likely
5346 ** to included crashing the application). The estimatedRows field should
5347 ** therefore only be used if [sqlite3_libversion_number()] returns a
5348 ** value greater than or equal to 3008002.
5349 */
5351  /* Inputs */
5352  int nConstraint; /* Number of entries in aConstraint */
5354  int iColumn; /* Column on left-hand side of constraint */
5355  unsigned char op; /* Constraint operator */
5356  unsigned char usable; /* True if this constraint is usable */
5357  int iTermOffset; /* Used internally - xBestIndex should ignore */
5358  } *aConstraint; /* Table of WHERE clause constraints */
5359  int nOrderBy; /* Number of terms in the ORDER BY clause */
5361  int iColumn; /* Column number */
5362  unsigned char desc; /* True for DESC. False for ASC. */
5363  } *aOrderBy; /* The ORDER BY clause */
5364  /* Outputs */
5366  int argvIndex; /* if >0, constraint is part of argv to xFilter */
5367  unsigned char omit; /* Do not code a test for this constraint */
5368  } *aConstraintUsage;
5369  int idxNum; /* Number used to identify the index */
5370  char *idxStr; /* String, possibly obtained from sqlite3_malloc */
5371  int needToFreeIdxStr; /* Free idxStr using sqlite3_free() if true */
5372  int orderByConsumed; /* True if output is already ordered */
5373  double estimatedCost; /* Estimated cost of using this index */
5374  /* Fields below are only available in SQLite 3.8.2 and later */
5375  sqlite3_int64 estimatedRows; /* Estimated number of rows returned */
5376 };
5377 
5378 /*
5379 ** CAPI3REF: Virtual Table Constraint Operator Codes
5380 **
5381 ** These macros defined the allowed values for the
5382 ** [sqlite3_index_info].aConstraint[].op field. Each value represents
5383 ** an operator that is part of a constraint term in the wHERE clause of
5384 ** a query that uses a [virtual table].
5385 */
5386 #define SQLITE_INDEX_CONSTRAINT_EQ 2
5387 #define SQLITE_INDEX_CONSTRAINT_GT 4
5388 #define SQLITE_INDEX_CONSTRAINT_LE 8
5389 #define SQLITE_INDEX_CONSTRAINT_LT 16
5390 #define SQLITE_INDEX_CONSTRAINT_GE 32
5391 #define SQLITE_INDEX_CONSTRAINT_MATCH 64
5392 
5393 /*
5394 ** CAPI3REF: Register A Virtual Table Implementation
5395 **
5396 ** ^These routines are used to register a new [virtual table module] name.
5397 ** ^Module names must be registered before
5398 ** creating a new [virtual table] using the module and before using a
5399 ** preexisting [virtual table] for the module.
5400 **
5401 ** ^The module name is registered on the [database connection] specified
5402 ** by the first parameter. ^The name of the module is given by the
5403 ** second parameter. ^The third parameter is a pointer to
5404 ** the implementation of the [virtual table module]. ^The fourth
5405 ** parameter is an arbitrary client data pointer that is passed through
5406 ** into the [xCreate] and [xConnect] methods of the virtual table module
5407 ** when a new virtual table is be being created or reinitialized.
5408 **
5409 ** ^The sqlite3_create_module_v2() interface has a fifth parameter which
5410 ** is a pointer to a destructor for the pClientData. ^SQLite will
5411 ** invoke the destructor function (if it is not NULL) when SQLite
5412 ** no longer needs the pClientData pointer. ^The destructor will also
5413 ** be invoked if the call to sqlite3_create_module_v2() fails.
5414 ** ^The sqlite3_create_module()
5415 ** interface is equivalent to sqlite3_create_module_v2() with a NULL
5416 ** destructor.
5417 */
5419  sqlite3 *db, /* SQLite connection to register module with */
5420  const char *zName, /* Name of the module */
5421  const sqlite3_module *p, /* Methods for the module */
5422  void *pClientData /* Client data for xCreate/xConnect */
5423 );
5425  sqlite3 *db, /* SQLite connection to register module with */
5426  const char *zName, /* Name of the module */
5427  const sqlite3_module *p, /* Methods for the module */
5428  void *pClientData, /* Client data for xCreate/xConnect */
5429  void(*xDestroy)(void*) /* Module destructor function */
5430 );
5431 
5432 /*
5433 ** CAPI3REF: Virtual Table Instance Object
5434 ** KEYWORDS: sqlite3_vtab
5435 **
5436 ** Every [virtual table module] implementation uses a subclass
5437 ** of this object to describe a particular instance
5438 ** of the [virtual table]. Each subclass will
5439 ** be tailored to the specific needs of the module implementation.
5440 ** The purpose of this superclass is to define certain fields that are
5441 ** common to all module implementations.
5442 **
5443 ** ^Virtual tables methods can set an error message by assigning a
5444 ** string obtained from [sqlite3_mprintf()] to zErrMsg. The method should
5445 ** take care that any prior string is freed by a call to [sqlite3_free()]
5446 ** prior to assigning a new string to zErrMsg. ^After the error message
5447 ** is delivered up to the client application, the string will be automatically
5448 ** freed by sqlite3_free() and the zErrMsg field will be zeroed.
5449 */
5451  const sqlite3_module *pModule; /* The module for this virtual table */
5452  int nRef; /* NO LONGER USED */
5453  char *zErrMsg; /* Error message from sqlite3_mprintf() */
5454  /* Virtual table implementations will typically add additional fields */
5455 };
5456 
5457 /*
5458 ** CAPI3REF: Virtual Table Cursor Object
5459 ** KEYWORDS: sqlite3_vtab_cursor {virtual table cursor}
5460 **
5461 ** Every [virtual table module] implementation uses a subclass of the
5462 ** following structure to describe cursors that point into the
5463 ** [virtual table] and are used
5464 ** to loop through the virtual table. Cursors are created using the
5465 ** [sqlite3_module.xOpen | xOpen] method of the module and are destroyed
5466 ** by the [sqlite3_module.xClose | xClose] method. Cursors are used
5467 ** by the [xFilter], [xNext], [xEof], [xColumn], and [xRowid] methods
5468 ** of the module. Each module implementation will define
5469 ** the content of a cursor structure to suit its own needs.
5470 **
5471 ** This superclass exists in order to define fields of the cursor that
5472 ** are common to all implementations.
5473 */
5475  sqlite3_vtab *pVtab; /* Virtual table of this cursor */
5476  /* Virtual table implementations will typically add additional fields */
5477 };
5478 
5479 /*
5480 ** CAPI3REF: Declare The Schema Of A Virtual Table
5481 **
5482 ** ^The [xCreate] and [xConnect] methods of a
5483 ** [virtual table module] call this interface
5484 ** to declare the format (the names and datatypes of the columns) of
5485 ** the virtual tables they implement.
5486 */
5487 SQLITE_API int sqlite3_declare_vtab(sqlite3*, const char *zSQL);
5488 
5489 /*
5490 ** CAPI3REF: Overload A Function For A Virtual Table
5491 **
5492 ** ^(Virtual tables can provide alternative implementations of functions
5493 ** using the [xFindFunction] method of the [virtual table module].
5494 ** But global versions of those functions
5495 ** must exist in order to be overloaded.)^
5496 **
5497 ** ^(This API makes sure a global version of a function with a particular
5498 ** name and number of parameters exists. If no such function exists
5499 ** before this API is called, a new function is created.)^ ^The implementation
5500 ** of the new function always causes an exception to be thrown. So
5501 ** the new function is not good for anything by itself. Its only
5502 ** purpose is to be a placeholder function that can be overloaded
5503 ** by a [virtual table].
5504 */
5505 SQLITE_API int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);
5506 
5507 /*
5508 ** The interface to the virtual-table mechanism defined above (back up
5509 ** to a comment remarkably similar to this one) is currently considered
5510 ** to be experimental. The interface might change in incompatible ways.
5511 ** If this is a problem for you, do not use the interface at this time.
5512 **
5513 ** When the virtual-table mechanism stabilizes, we will declare the
5514 ** interface fixed, support it indefinitely, and remove this comment.
5515 */
5516 
5517 /*
5518 ** CAPI3REF: A Handle To An Open BLOB
5519 ** KEYWORDS: {BLOB handle} {BLOB handles}
5520 **
5521 ** An instance of this object represents an open BLOB on which
5522 ** [sqlite3_blob_open | incremental BLOB I/O] can be performed.
5523 ** ^Objects of this type are created by [sqlite3_blob_open()]
5524 ** and destroyed by [sqlite3_blob_close()].
5525 ** ^The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces
5526 ** can be used to read or write small subsections of the BLOB.
5527 ** ^The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes.
5528 */
5530 
5531 /*
5532 ** CAPI3REF: Open A BLOB For Incremental I/O
5533 **
5534 ** ^(This interfaces opens a [BLOB handle | handle] to the BLOB located
5535 ** in row iRow, column zColumn, table zTable in database zDb;
5536 ** in other words, the same BLOB that would be selected by:
5537 **
5538 ** <pre>
5539 ** SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow;
5540 ** </pre>)^
5541 **
5542 ** ^If the flags parameter is non-zero, then the BLOB is opened for read
5543 ** and write access. ^If it is zero, the BLOB is opened for read access.
5544 ** ^It is not possible to open a column that is part of an index or primary
5545 ** key for writing. ^If [foreign key constraints] are enabled, it is
5546 ** not possible to open a column that is part of a [child key] for writing.
5547 **
5548 ** ^Note that the database name is not the filename that contains
5549 ** the database but rather the symbolic name of the database that
5550 ** appears after the AS keyword when the database is connected using [ATTACH].
5551 ** ^For the main database file, the database name is "main".
5552 ** ^For TEMP tables, the database name is "temp".
5553 **
5554 ** ^(On success, [SQLITE_OK] is returned and the new [BLOB handle] is written
5555 ** to *ppBlob. Otherwise an [error code] is returned and *ppBlob is set
5556 ** to be a null pointer.)^
5557 ** ^This function sets the [database connection] error code and message
5558 ** accessible via [sqlite3_errcode()] and [sqlite3_errmsg()] and related
5559 ** functions. ^Note that the *ppBlob variable is always initialized in a
5560 ** way that makes it safe to invoke [sqlite3_blob_close()] on *ppBlob
5561 ** regardless of the success or failure of this routine.
5562 **
5563 ** ^(If the row that a BLOB handle points to is modified by an
5564 ** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
5565 ** then the BLOB handle is marked as "expired".
5566 ** This is true if any column of the row is changed, even a column
5567 ** other than the one the BLOB handle is open on.)^
5568 ** ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
5569 ** an expired BLOB handle fail with a return code of [SQLITE_ABORT].
5570 ** ^(Changes written into a BLOB prior to the BLOB expiring are not
5571 ** rolled back by the expiration of the BLOB. Such changes will eventually
5572 ** commit if the transaction continues to completion.)^
5573 **
5574 ** ^Use the [sqlite3_blob_bytes()] interface to determine the size of
5575 ** the opened blob. ^The size of a blob may not be changed by this
5576 ** interface. Use the [UPDATE] SQL command to change the size of a
5577 ** blob.
5578 **
5579 ** ^The [sqlite3_blob_open()] interface will fail for a [WITHOUT ROWID]
5580 ** table. Incremental BLOB I/O is not possible on [WITHOUT ROWID] tables.
5581 **
5582 ** ^The [sqlite3_bind_zeroblob()] and [sqlite3_result_zeroblob()] interfaces
5583 ** and the built-in [zeroblob] SQL function can be used, if desired,
5584 ** to create an empty, zero-filled blob in which to read or write using
5585 ** this interface.
5586 **
5587 ** To avoid a resource leak, every open [BLOB handle] should eventually
5588 ** be released by a call to [sqlite3_blob_close()].
5589 */
5591  sqlite3*,
5592  const char *zDb,
5593  const char *zTable,
5594  const char *zColumn,
5595  sqlite3_int64 iRow,
5596  int flags,
5597  sqlite3_blob **ppBlob
5598 );
5599 
5600 /*
5601 ** CAPI3REF: Move a BLOB Handle to a New Row
5602 **
5603 ** ^This function is used to move an existing blob handle so that it points
5604 ** to a different row of the same database table. ^The new row is identified
5605 ** by the rowid value passed as the second argument. Only the row can be
5606 ** changed. ^The database, table and column on which the blob handle is open
5607 ** remain the same. Moving an existing blob handle to a new row can be
5608 ** faster than closing the existing handle and opening a new one.
5609 **
5610 ** ^(The new row must meet the same criteria as for [sqlite3_blob_open()] -
5611 ** it must exist and there must be either a blob or text value stored in
5612 ** the nominated column.)^ ^If the new row is not present in the table, or if
5613 ** it does not contain a blob or text value, or if another error occurs, an
5614 ** SQLite error code is returned and the blob handle is considered aborted.
5615 ** ^All subsequent calls to [sqlite3_blob_read()], [sqlite3_blob_write()] or
5616 ** [sqlite3_blob_reopen()] on an aborted blob handle immediately return
5617 ** SQLITE_ABORT. ^Calling [sqlite3_blob_bytes()] on an aborted blob handle
5618 ** always returns zero.
5619 **
5620 ** ^This function sets the database handle error code and message.
5621 */
5623 
5624 /*
5625 ** CAPI3REF: Close A BLOB Handle
5626 **
5627 ** ^Closes an open [BLOB handle].
5628 **
5629 ** ^Closing a BLOB shall cause the current transaction to commit
5630 ** if there are no other BLOBs, no pending prepared statements, and the
5631 ** database connection is in [autocommit mode].
5632 ** ^If any writes were made to the BLOB, they might be held in cache
5633 ** until the close operation if they will fit.
5634 **
5635 ** ^(Closing the BLOB often forces the changes
5636 ** out to disk and so if any I/O errors occur, they will likely occur
5637 ** at the time when the BLOB is closed. Any errors that occur during
5638 ** closing are reported as a non-zero return value.)^
5639 **
5640 ** ^(The BLOB is closed unconditionally. Even if this routine returns
5641 ** an error code, the BLOB is still closed.)^
5642 **
5643 ** ^Calling this routine with a null pointer (such as would be returned
5644 ** by a failed call to [sqlite3_blob_open()]) is a harmless no-op.
5645 */
5647 
5648 /*
5649 ** CAPI3REF: Return The Size Of An Open BLOB
5650 **
5651 ** ^Returns the size in bytes of the BLOB accessible via the
5652 ** successfully opened [BLOB handle] in its only argument. ^The
5653 ** incremental blob I/O routines can only read or overwriting existing
5654 ** blob content; they cannot change the size of a blob.
5655 **
5656 ** This routine only works on a [BLOB handle] which has been created
5657 ** by a prior successful call to [sqlite3_blob_open()] and which has not
5658 ** been closed by [sqlite3_blob_close()]. Passing any other pointer in
5659 ** to this routine results in undefined and probably undesirable behavior.
5660 */
5662 
5663 /*
5664 ** CAPI3REF: Read Data From A BLOB Incrementally
5665 **
5666 ** ^(This function is used to read data from an open [BLOB handle] into a
5667 ** caller-supplied buffer. N bytes of data are copied into buffer Z
5668 ** from the open BLOB, starting at offset iOffset.)^
5669 **
5670 ** ^If offset iOffset is less than N bytes from the end of the BLOB,
5671 ** [SQLITE_ERROR] is returned and no data is read. ^If N or iOffset is
5672 ** less than zero, [SQLITE_ERROR] is returned and no data is read.
5673 ** ^The size of the blob (and hence the maximum value of N+iOffset)
5674 ** can be determined using the [sqlite3_blob_bytes()] interface.
5675 **
5676 ** ^An attempt to read from an expired [BLOB handle] fails with an
5677 ** error code of [SQLITE_ABORT].
5678 **
5679 ** ^(On success, sqlite3_blob_read() returns SQLITE_OK.
5680 ** Otherwise, an [error code] or an [extended error code] is returned.)^
5681 **
5682 ** This routine only works on a [BLOB handle] which has been created
5683 ** by a prior successful call to [sqlite3_blob_open()] and which has not
5684 ** been closed by [sqlite3_blob_close()]. Passing any other pointer in
5685 ** to this routine results in undefined and probably undesirable behavior.
5686 **
5687 ** See also: [sqlite3_blob_write()].
5688 */
5689 SQLITE_API int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);
5690 
5691 /*
5692 ** CAPI3REF: Write Data Into A BLOB Incrementally
5693 **
5694 ** ^This function is used to write data into an open [BLOB handle] from a
5695 ** caller-supplied buffer. ^N bytes of data are copied from the buffer Z
5696 ** into the open BLOB, starting at offset iOffset.
5697 **
5698 ** ^If the [BLOB handle] passed as the first argument was not opened for
5699 ** writing (the flags parameter to [sqlite3_blob_open()] was zero),
5700 ** this function returns [SQLITE_READONLY].
5701 **
5702 ** ^This function may only modify the contents of the BLOB; it is
5703 ** not possible to increase the size of a BLOB using this API.
5704 ** ^If offset iOffset is less than N bytes from the end of the BLOB,
5705 ** [SQLITE_ERROR] is returned and no data is written. ^If N is
5706 ** less than zero [SQLITE_ERROR] is returned and no data is written.
5707 ** The size of the BLOB (and hence the maximum value of N+iOffset)
5708 ** can be determined using the [sqlite3_blob_bytes()] interface.
5709 **
5710 ** ^An attempt to write to an expired [BLOB handle] fails with an
5711 ** error code of [SQLITE_ABORT]. ^Writes to the BLOB that occurred
5712 ** before the [BLOB handle] expired are not rolled back by the
5713 ** expiration of the handle, though of course those changes might
5714 ** have been overwritten by the statement that expired the BLOB handle
5715 ** or by other independent statements.
5716 **
5717 ** ^(On success, sqlite3_blob_write() returns SQLITE_OK.
5718 ** Otherwise, an [error code] or an [extended error code] is returned.)^
5719 **
5720 ** This routine only works on a [BLOB handle] which has been created
5721 ** by a prior successful call to [sqlite3_blob_open()] and which has not
5722 ** been closed by [sqlite3_blob_close()]. Passing any other pointer in
5723 ** to this routine results in undefined and probably undesirable behavior.
5724 **
5725 ** See also: [sqlite3_blob_read()].
5726 */
5727 SQLITE_API int sqlite3_blob_write(sqlite3_blob *, const void *z, int n, int iOffset);
5728 
5729 /*
5730 ** CAPI3REF: Virtual File System Objects
5731 **
5732 ** A virtual filesystem (VFS) is an [sqlite3_vfs] object
5733 ** that SQLite uses to interact
5734 ** with the underlying operating system. Most SQLite builds come with a
5735 ** single default VFS that is appropriate for the host computer.
5736 ** New VFSes can be registered and existing VFSes can be unregistered.
5737 ** The following interfaces are provided.
5738 **
5739 ** ^The sqlite3_vfs_find() interface returns a pointer to a VFS given its name.
5740 ** ^Names are case sensitive.
5741 ** ^Names are zero-terminated UTF-8 strings.
5742 ** ^If there is no match, a NULL pointer is returned.
5743 ** ^If zVfsName is NULL then the default VFS is returned.
5744 **
5745 ** ^New VFSes are registered with sqlite3_vfs_register().
5746 ** ^Each new VFS becomes the default VFS if the makeDflt flag is set.
5747 ** ^The same VFS can be registered multiple times without injury.
5748 ** ^To make an existing VFS into the default VFS, register it again
5749 ** with the makeDflt flag set. If two different VFSes with the
5750 ** same name are registered, the behavior is undefined. If a
5751 ** VFS is registered with a name that is NULL or an empty string,
5752 ** then the behavior is undefined.
5753 **
5754 ** ^Unregister a VFS with the sqlite3_vfs_unregister() interface.
5755 ** ^(If the default VFS is unregistered, another VFS is chosen as
5756 ** the default. The choice for the new VFS is arbitrary.)^
5757 */
5758 SQLITE_API sqlite3_vfs *sqlite3_vfs_find(const char *zVfsName);
5759 SQLITE_API int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt);
5760 SQLITE_API int sqlite3_vfs_unregister(sqlite3_vfs*);
5761 
5762 /*
5763 ** CAPI3REF: Mutexes
5764 **
5765 ** The SQLite core uses these routines for thread
5766 ** synchronization. Though they are intended for internal
5767 ** use by SQLite, code that links against SQLite is
5768 ** permitted to use any of these routines.
5769 **
5770 ** The SQLite source code contains multiple implementations
5771 ** of these mutex routines. An appropriate implementation
5772 ** is selected automatically at compile-time. ^(The following
5773 ** implementations are available in the SQLite core:
5774 **
5775 ** <ul>
5776 ** <li> SQLITE_MUTEX_PTHREADS
5777 ** <li> SQLITE_MUTEX_W32
5778 ** <li> SQLITE_MUTEX_NOOP
5779 ** </ul>)^
5780 **
5781 ** ^The SQLITE_MUTEX_NOOP implementation is a set of routines
5782 ** that does no real locking and is appropriate for use in
5783 ** a single-threaded application. ^The SQLITE_MUTEX_PTHREADS and
5784 ** SQLITE_MUTEX_W32 implementations are appropriate for use on Unix
5785 ** and Windows.
5786 **
5787 ** ^(If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor
5788 ** macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex
5789 ** implementation is included with the library. In this case the
5790 ** application must supply a custom mutex implementation using the
5791 ** [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function
5792 ** before calling sqlite3_initialize() or any other public sqlite3_
5793 ** function that calls sqlite3_initialize().)^
5794 **
5795 ** ^The sqlite3_mutex_alloc() routine allocates a new
5796 ** mutex and returns a pointer to it. ^If it returns NULL
5797 ** that means that a mutex could not be allocated. ^SQLite
5798 ** will unwind its stack and return an error. ^(The argument
5799 ** to sqlite3_mutex_alloc() is one of these integer constants:
5800 **
5801 ** <ul>
5802 ** <li> SQLITE_MUTEX_FAST
5803 ** <li> SQLITE_MUTEX_RECURSIVE
5804 ** <li> SQLITE_MUTEX_STATIC_MASTER
5805 ** <li> SQLITE_MUTEX_STATIC_MEM
5806 ** <li> SQLITE_MUTEX_STATIC_MEM2
5807 ** <li> SQLITE_MUTEX_STATIC_PRNG
5808 ** <li> SQLITE_MUTEX_STATIC_LRU
5809 ** <li> SQLITE_MUTEX_STATIC_LRU2
5810 ** </ul>)^
5811 **
5812 ** ^The first two constants (SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE)
5813 ** cause sqlite3_mutex_alloc() to create
5814 ** a new mutex. ^The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
5815 ** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
5816 ** The mutex implementation does not need to make a distinction
5817 ** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
5818 ** not want to. ^SQLite will only request a recursive mutex in
5819 ** cases where it really needs one. ^If a faster non-recursive mutex
5820 ** implementation is available on the host platform, the mutex subsystem
5821 ** might return such a mutex in response to SQLITE_MUTEX_FAST.
5822 **
5823 ** ^The other allowed parameters to sqlite3_mutex_alloc() (anything other
5824 ** than SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE) each return
5825 ** a pointer to a static preexisting mutex. ^Six static mutexes are
5826 ** used by the current version of SQLite. Future versions of SQLite
5827 ** may add additional static mutexes. Static mutexes are for internal
5828 ** use by SQLite only. Applications that use SQLite mutexes should
5829 ** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
5830 ** SQLITE_MUTEX_RECURSIVE.
5831 **
5832 ** ^Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
5833 ** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
5834 ** returns a different mutex on every call. ^But for the static
5835 ** mutex types, the same mutex is returned on every call that has
5836 ** the same type number.
5837 **
5838 ** ^The sqlite3_mutex_free() routine deallocates a previously
5839 ** allocated dynamic mutex. ^SQLite is careful to deallocate every
5840 ** dynamic mutex that it allocates. The dynamic mutexes must not be in
5841 ** use when they are deallocated. Attempting to deallocate a static
5842 ** mutex results in undefined behavior. ^SQLite never deallocates
5843 ** a static mutex.
5844 **
5845 ** ^The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
5846 ** to enter a mutex. ^If another thread is already within the mutex,
5847 ** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
5848 ** SQLITE_BUSY. ^The sqlite3_mutex_try() interface returns [SQLITE_OK]
5849 ** upon successful entry. ^(Mutexes created using
5850 ** SQLITE_MUTEX_RECURSIVE can be entered multiple times by the same thread.
5851 ** In such cases the,
5852 ** mutex must be exited an equal number of times before another thread
5853 ** can enter.)^ ^(If the same thread tries to enter any other
5854 ** kind of mutex more than once, the behavior is undefined.
5855 ** SQLite will never exhibit
5856 ** such behavior in its own use of mutexes.)^
5857 **
5858 ** ^(Some systems (for example, Windows 95) do not support the operation
5859 ** implemented by sqlite3_mutex_try(). On those systems, sqlite3_mutex_try()
5860 ** will always return SQLITE_BUSY. The SQLite core only ever uses
5861 ** sqlite3_mutex_try() as an optimization so this is acceptable behavior.)^
5862 **
5863 ** ^The sqlite3_mutex_leave() routine exits a mutex that was
5864 ** previously entered by the same thread. ^(The behavior
5865 ** is undefined if the mutex is not currently entered by the
5866 ** calling thread or is not currently allocated. SQLite will
5867 ** never do either.)^
5868 **
5869 ** ^If the argument to sqlite3_mutex_enter(), sqlite3_mutex_try(), or
5870 ** sqlite3_mutex_leave() is a NULL pointer, then all three routines
5871 ** behave as no-ops.
5872 **
5873 ** See also: [sqlite3_mutex_held()] and [sqlite3_mutex_notheld()].
5874 */