sqlite3.h revision 226031
1/* 2** 2001 September 15 3** 4** The author disclaims copyright to this source code. In place of 5** a legal notice, here is a blessing: 6** 7** May you do good and not evil. 8** May you find forgiveness for yourself and forgive others. 9** May you share freely, never taking more than you give. 10** 11************************************************************************* 12** This header file defines the interface that the SQLite library 13** presents to client programs. If a C-function, structure, datatype, 14** or constant definition does not appear in this file, then it is 15** not a published API of SQLite, is subject to change without 16** notice, and should not be referenced by programs that use SQLite. 17** 18** Some of the definitions that are in this file are marked as 19** "experimental". Experimental interfaces are normally new 20** features recently added to SQLite. We do not anticipate changes 21** to experimental interfaces but reserve the right to make minor changes 22** if experience from use "in the wild" suggest such changes are prudent. 23** 24** The official C-language API documentation for SQLite is derived 25** from comments in this file. This file is the authoritative source 26** on how SQLite interfaces are suppose to operate. 27** 28** The name of this file under configuration management is "sqlite.h.in". 29** The makefile makes some minor changes to this file (such as inserting 30** the version number) and changes its name to "sqlite3.h" as 31** part of the build process. 32*/ 33#ifndef _SQLITE3_H_ 34#define _SQLITE3_H_ 35#include <stdarg.h> /* Needed for the definition of va_list */ 36 37/* 38** Make sure we can call this stuff from C++. 39*/ 40#ifdef __cplusplus 41extern "C" { 42#endif 43 44 45/* 46** Add the ability to override 'extern' 47*/ 48#ifndef SQLITE_EXTERN 49# define SQLITE_EXTERN extern 50#endif 51 52#ifndef SQLITE_API 53# define SQLITE_API 54#endif 55 56 57/* 58** These no-op macros are used in front of interfaces to mark those 59** interfaces as either deprecated or experimental. New applications 60** should not use deprecated interfaces - they are support for backwards 61** compatibility only. Application writers should be aware that 62** experimental interfaces are subject to change in point releases. 63** 64** These macros used to resolve to various kinds of compiler magic that 65** would generate warning messages when they were used. But that 66** compiler magic ended up generating such a flurry of bug reports 67** that we have taken it all out and gone back to using simple 68** noop macros. 69*/ 70#define SQLITE_DEPRECATED 71#define SQLITE_EXPERIMENTAL 72 73/* 74** Ensure these symbols were not defined by some previous header file. 75*/ 76#ifdef SQLITE_VERSION 77# undef SQLITE_VERSION 78#endif 79#ifdef SQLITE_VERSION_NUMBER 80# undef SQLITE_VERSION_NUMBER 81#endif 82 83/* 84** CAPI3REF: Compile-Time Library Version Numbers 85** 86** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header 87** evaluates to a string literal that is the SQLite version in the 88** format "X.Y.Z" where X is the major version number (always 3 for 89** SQLite3) and Y is the minor version number and Z is the release number.)^ 90** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer 91** with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z are the same 92** numbers used in [SQLITE_VERSION].)^ 93** The SQLITE_VERSION_NUMBER for any given release of SQLite will also 94** be larger than the release from which it is derived. Either Y will 95** be held constant and Z will be incremented or else Y will be incremented 96** and Z will be reset to zero. 97** 98** Since version 3.6.18, SQLite source code has been stored in the 99** <a href="http://www.fossil-scm.org/">Fossil configuration management 100** system</a>. ^The SQLITE_SOURCE_ID macro evalutes to 101** a string which identifies a particular check-in of SQLite 102** within its configuration management system. ^The SQLITE_SOURCE_ID 103** string contains the date and time of the check-in (UTC) and an SHA1 104** hash of the entire source tree. 105** 106** See also: [sqlite3_libversion()], 107** [sqlite3_libversion_number()], [sqlite3_sourceid()], 108** [sqlite_version()] and [sqlite_source_id()]. 109*/ 110#define SQLITE_VERSION "3.6.23.1" 111#define SQLITE_VERSION_NUMBER 3006023 112#define SQLITE_SOURCE_ID "2010-03-26 22:28:06 b078b588d617e07886ad156e9f54ade6d823568e" 113 114/* 115** CAPI3REF: Run-Time Library Version Numbers 116** KEYWORDS: sqlite3_version, sqlite3_sourceid 117** 118** These interfaces provide the same information as the [SQLITE_VERSION], 119** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros 120** but are associated with the library instead of the header file. ^(Cautious 121** programmers might include assert() statements in their application to 122** verify that values returned by these interfaces match the macros in 123** the header, and thus insure that the application is 124** compiled with matching library and header files. 125** 126** <blockquote><pre> 127** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER ); 128** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 ); 129** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 ); 130** </pre></blockquote>)^ 131** 132** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION] 133** macro. ^The sqlite3_libversion() function returns a pointer to the 134** to the sqlite3_version[] string constant. The sqlite3_libversion() 135** function is provided for use in DLLs since DLL users usually do not have 136** direct access to string constants within the DLL. ^The 137** sqlite3_libversion_number() function returns an integer equal to 138** [SQLITE_VERSION_NUMBER]. ^The sqlite3_sourceid() function returns 139** a pointer to a string constant whose value is the same as the 140** [SQLITE_SOURCE_ID] C preprocessor macro. 141** 142** See also: [sqlite_version()] and [sqlite_source_id()]. 143*/ 144SQLITE_API SQLITE_EXTERN const char sqlite3_version[]; 145SQLITE_API const char *sqlite3_libversion(void); 146SQLITE_API const char *sqlite3_sourceid(void); 147SQLITE_API int sqlite3_libversion_number(void); 148 149#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS 150/* 151** CAPI3REF: Run-Time Library Compilation Options Diagnostics 152** 153** ^The sqlite3_compileoption_used() function returns 0 or 1 154** indicating whether the specified option was defined at 155** compile time. ^The SQLITE_ prefix may be omitted from the 156** option name passed to sqlite3_compileoption_used(). 157** 158** ^The sqlite3_compileoption_get() function allows interating 159** over the list of options that were defined at compile time by 160** returning the N-th compile time option string. ^If N is out of range, 161** sqlite3_compileoption_get() returns a NULL pointer. ^The SQLITE_ 162** prefix is omitted from any strings returned by 163** sqlite3_compileoption_get(). 164** 165** ^Support for the diagnostic functions sqlite3_compileoption_used() 166** and sqlite3_compileoption_get() may be omitted by specifing the 167** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time. 168** 169** See also: SQL functions [sqlite_compileoption_used()] and 170** [sqlite_compileoption_get()] and the [compile_options pragma]. 171*/ 172SQLITE_API int sqlite3_compileoption_used(const char *zOptName); 173SQLITE_API const char *sqlite3_compileoption_get(int N); 174#endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */ 175 176/* 177** CAPI3REF: Test To See If The Library Is Threadsafe 178** 179** ^The sqlite3_threadsafe() function returns zero if and only if 180** SQLite was compiled mutexing code omitted due to the 181** [SQLITE_THREADSAFE] compile-time option being set to 0. 182** 183** SQLite can be compiled with or without mutexes. When 184** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes 185** are enabled and SQLite is threadsafe. When the 186** [SQLITE_THREADSAFE] macro is 0, 187** the mutexes are omitted. Without the mutexes, it is not safe 188** to use SQLite concurrently from more than one thread. 189** 190** Enabling mutexes incurs a measurable performance penalty. 191** So if speed is of utmost importance, it makes sense to disable 192** the mutexes. But for maximum safety, mutexes should be enabled. 193** ^The default behavior is for mutexes to be enabled. 194** 195** This interface can be used by an application to make sure that the 196** version of SQLite that it is linking against was compiled with 197** the desired setting of the [SQLITE_THREADSAFE] macro. 198** 199** This interface only reports on the compile-time mutex setting 200** of the [SQLITE_THREADSAFE] flag. If SQLite is compiled with 201** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but 202** can be fully or partially disabled using a call to [sqlite3_config()] 203** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD], 204** or [SQLITE_CONFIG_MUTEX]. ^(The return value of the 205** sqlite3_threadsafe() function shows only the compile-time setting of 206** thread safety, not any run-time changes to that setting made by 207** sqlite3_config(). In other words, the return value from sqlite3_threadsafe() 208** is unchanged by calls to sqlite3_config().)^ 209** 210** See the [threading mode] documentation for additional information. 211*/ 212SQLITE_API int sqlite3_threadsafe(void); 213 214/* 215** CAPI3REF: Database Connection Handle 216** KEYWORDS: {database connection} {database connections} 217** 218** Each open SQLite database is represented by a pointer to an instance of 219** the opaque structure named "sqlite3". It is useful to think of an sqlite3 220** pointer as an object. The [sqlite3_open()], [sqlite3_open16()], and 221** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()] 222** is its destructor. There are many other interfaces (such as 223** [sqlite3_prepare_v2()], [sqlite3_create_function()], and 224** [sqlite3_busy_timeout()] to name but three) that are methods on an 225** sqlite3 object. 226*/ 227typedef struct sqlite3 sqlite3; 228 229/* 230** CAPI3REF: 64-Bit Integer Types 231** KEYWORDS: sqlite_int64 sqlite_uint64 232** 233** Because there is no cross-platform way to specify 64-bit integer types 234** SQLite includes typedefs for 64-bit signed and unsigned integers. 235** 236** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions. 237** The sqlite_int64 and sqlite_uint64 types are supported for backwards 238** compatibility only. 239** 240** ^The sqlite3_int64 and sqlite_int64 types can store integer values 241** between -9223372036854775808 and +9223372036854775807 inclusive. ^The 242** sqlite3_uint64 and sqlite_uint64 types can store integer values 243** between 0 and +18446744073709551615 inclusive. 244*/ 245#ifdef SQLITE_INT64_TYPE 246 typedef SQLITE_INT64_TYPE sqlite_int64; 247 typedef unsigned SQLITE_INT64_TYPE sqlite_uint64; 248#elif defined(_MSC_VER) || defined(__BORLANDC__) 249 typedef __int64 sqlite_int64; 250 typedef unsigned __int64 sqlite_uint64; 251#else 252 typedef long long int sqlite_int64; 253 typedef unsigned long long int sqlite_uint64; 254#endif 255typedef sqlite_int64 sqlite3_int64; 256typedef sqlite_uint64 sqlite3_uint64; 257 258/* 259** If compiling for a processor that lacks floating point support, 260** substitute integer for floating-point. 261*/ 262#ifdef SQLITE_OMIT_FLOATING_POINT 263# define double sqlite3_int64 264#endif 265 266/* 267** CAPI3REF: Closing A Database Connection 268** 269** ^The sqlite3_close() routine is the destructor for the [sqlite3] object. 270** ^Calls to sqlite3_close() return SQLITE_OK if the [sqlite3] object is 271** successfullly destroyed and all associated resources are deallocated. 272** 273** Applications must [sqlite3_finalize | finalize] all [prepared statements] 274** and [sqlite3_blob_close | close] all [BLOB handles] associated with 275** the [sqlite3] object prior to attempting to close the object. ^If 276** sqlite3_close() is called on a [database connection] that still has 277** outstanding [prepared statements] or [BLOB handles], then it returns 278** SQLITE_BUSY. 279** 280** ^If [sqlite3_close()] is invoked while a transaction is open, 281** the transaction is automatically rolled back. 282** 283** The C parameter to [sqlite3_close(C)] must be either a NULL 284** pointer or an [sqlite3] object pointer obtained 285** from [sqlite3_open()], [sqlite3_open16()], or 286** [sqlite3_open_v2()], and not previously closed. 287** ^Calling sqlite3_close() with a NULL pointer argument is a 288** harmless no-op. 289*/ 290SQLITE_API int sqlite3_close(sqlite3 *); 291 292/* 293** The type for a callback function. 294** This is legacy and deprecated. It is included for historical 295** compatibility and is not documented. 296*/ 297typedef int (*sqlite3_callback)(void*,int,char**, char**); 298 299/* 300** CAPI3REF: One-Step Query Execution Interface 301** 302** The sqlite3_exec() interface is a convenience wrapper around 303** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()], 304** that allows an application to run multiple statements of SQL 305** without having to use a lot of C code. 306** 307** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded, 308** semicolon-separate SQL statements passed into its 2nd argument, 309** in the context of the [database connection] passed in as its 1st 310** argument. ^If the callback function of the 3rd argument to 311** sqlite3_exec() is not NULL, then it is invoked for each result row 312** coming out of the evaluated SQL statements. ^The 4th argument to 313** to sqlite3_exec() is relayed through to the 1st argument of each 314** callback invocation. ^If the callback pointer to sqlite3_exec() 315** is NULL, then no callback is ever invoked and result rows are 316** ignored. 317** 318** ^If an error occurs while evaluating the SQL statements passed into 319** sqlite3_exec(), then execution of the current statement stops and 320** subsequent statements are skipped. ^If the 5th parameter to sqlite3_exec() 321** is not NULL then any error message is written into memory obtained 322** from [sqlite3_malloc()] and passed back through the 5th parameter. 323** To avoid memory leaks, the application should invoke [sqlite3_free()] 324** on error message strings returned through the 5th parameter of 325** of sqlite3_exec() after the error message string is no longer needed. 326** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors 327** occur, then sqlite3_exec() sets the pointer in its 5th parameter to 328** NULL before returning. 329** 330** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec() 331** routine returns SQLITE_ABORT without invoking the callback again and 332** without running any subsequent SQL statements. 333** 334** ^The 2nd argument to the sqlite3_exec() callback function is the 335** number of columns in the result. ^The 3rd argument to the sqlite3_exec() 336** callback is an array of pointers to strings obtained as if from 337** [sqlite3_column_text()], one for each column. ^If an element of a 338** result row is NULL then the corresponding string pointer for the 339** sqlite3_exec() callback is a NULL pointer. ^The 4th argument to the 340** sqlite3_exec() callback is an array of pointers to strings where each 341** entry represents the name of corresponding result column as obtained 342** from [sqlite3_column_name()]. 343** 344** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer 345** to an empty string, or a pointer that contains only whitespace and/or 346** SQL comments, then no SQL statements are evaluated and the database 347** is not changed. 348** 349** Restrictions: 350** 351** <ul> 352** <li> The application must insure that the 1st parameter to sqlite3_exec() 353** is a valid and open [database connection]. 354** <li> The application must not close [database connection] specified by 355** the 1st parameter to sqlite3_exec() while sqlite3_exec() is running. 356** <li> The application must not modify the SQL statement text passed into 357** the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running. 358** </ul> 359*/ 360SQLITE_API int sqlite3_exec( 361 sqlite3*, /* An open database */ 362 const char *sql, /* SQL to be evaluated */ 363 int (*callback)(void*,int,char**,char**), /* Callback function */ 364 void *, /* 1st argument to callback */ 365 char **errmsg /* Error msg written here */ 366); 367 368/* 369** CAPI3REF: Result Codes 370** KEYWORDS: SQLITE_OK {error code} {error codes} 371** KEYWORDS: {result code} {result codes} 372** 373** Many SQLite functions return an integer result code from the set shown 374** here in order to indicates success or failure. 375** 376** New error codes may be added in future versions of SQLite. 377** 378** See also: [SQLITE_IOERR_READ | extended result codes] 379*/ 380#define SQLITE_OK 0 /* Successful result */ 381/* beginning-of-error-codes */ 382#define SQLITE_ERROR 1 /* SQL error or missing database */ 383#define SQLITE_INTERNAL 2 /* Internal logic error in SQLite */ 384#define SQLITE_PERM 3 /* Access permission denied */ 385#define SQLITE_ABORT 4 /* Callback routine requested an abort */ 386#define SQLITE_BUSY 5 /* The database file is locked */ 387#define SQLITE_LOCKED 6 /* A table in the database is locked */ 388#define SQLITE_NOMEM 7 /* A malloc() failed */ 389#define SQLITE_READONLY 8 /* Attempt to write a readonly database */ 390#define SQLITE_INTERRUPT 9 /* Operation terminated by sqlite3_interrupt()*/ 391#define SQLITE_IOERR 10 /* Some kind of disk I/O error occurred */ 392#define SQLITE_CORRUPT 11 /* The database disk image is malformed */ 393#define SQLITE_NOTFOUND 12 /* NOT USED. Table or record not found */ 394#define SQLITE_FULL 13 /* Insertion failed because database is full */ 395#define SQLITE_CANTOPEN 14 /* Unable to open the database file */ 396#define SQLITE_PROTOCOL 15 /* NOT USED. Database lock protocol error */ 397#define SQLITE_EMPTY 16 /* Database is empty */ 398#define SQLITE_SCHEMA 17 /* The database schema changed */ 399#define SQLITE_TOOBIG 18 /* String or BLOB exceeds size limit */ 400#define SQLITE_CONSTRAINT 19 /* Abort due to constraint violation */ 401#define SQLITE_MISMATCH 20 /* Data type mismatch */ 402#define SQLITE_MISUSE 21 /* Library used incorrectly */ 403#define SQLITE_NOLFS 22 /* Uses OS features not supported on host */ 404#define SQLITE_AUTH 23 /* Authorization denied */ 405#define SQLITE_FORMAT 24 /* Auxiliary database format error */ 406#define SQLITE_RANGE 25 /* 2nd parameter to sqlite3_bind out of range */ 407#define SQLITE_NOTADB 26 /* File opened that is not a database file */ 408#define SQLITE_ROW 100 /* sqlite3_step() has another row ready */ 409#define SQLITE_DONE 101 /* sqlite3_step() has finished executing */ 410/* end-of-error-codes */ 411 412/* 413** CAPI3REF: Extended Result Codes 414** KEYWORDS: {extended error code} {extended error codes} 415** KEYWORDS: {extended result code} {extended result codes} 416** 417** In its default configuration, SQLite API routines return one of 26 integer 418** [SQLITE_OK | result codes]. However, experience has shown that many of 419** these result codes are too coarse-grained. They do not provide as 420** much information about problems as programmers might like. In an effort to 421** address this, newer versions of SQLite (version 3.3.8 and later) include 422** support for additional result codes that provide more detailed information 423** about errors. The extended result codes are enabled or disabled 424** on a per database connection basis using the 425** [sqlite3_extended_result_codes()] API. 426** 427** Some of the available extended result codes are listed here. 428** One may expect the number of extended result codes will be expand 429** over time. Software that uses extended result codes should expect 430** to see new result codes in future releases of SQLite. 431** 432** The SQLITE_OK result code will never be extended. It will always 433** be exactly zero. 434*/ 435#define SQLITE_IOERR_READ (SQLITE_IOERR | (1<<8)) 436#define SQLITE_IOERR_SHORT_READ (SQLITE_IOERR | (2<<8)) 437#define SQLITE_IOERR_WRITE (SQLITE_IOERR | (3<<8)) 438#define SQLITE_IOERR_FSYNC (SQLITE_IOERR | (4<<8)) 439#define SQLITE_IOERR_DIR_FSYNC (SQLITE_IOERR | (5<<8)) 440#define SQLITE_IOERR_TRUNCATE (SQLITE_IOERR | (6<<8)) 441#define SQLITE_IOERR_FSTAT (SQLITE_IOERR | (7<<8)) 442#define SQLITE_IOERR_UNLOCK (SQLITE_IOERR | (8<<8)) 443#define SQLITE_IOERR_RDLOCK (SQLITE_IOERR | (9<<8)) 444#define SQLITE_IOERR_DELETE (SQLITE_IOERR | (10<<8)) 445#define SQLITE_IOERR_BLOCKED (SQLITE_IOERR | (11<<8)) 446#define SQLITE_IOERR_NOMEM (SQLITE_IOERR | (12<<8)) 447#define SQLITE_IOERR_ACCESS (SQLITE_IOERR | (13<<8)) 448#define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8)) 449#define SQLITE_IOERR_LOCK (SQLITE_IOERR | (15<<8)) 450#define SQLITE_IOERR_CLOSE (SQLITE_IOERR | (16<<8)) 451#define SQLITE_IOERR_DIR_CLOSE (SQLITE_IOERR | (17<<8)) 452#define SQLITE_LOCKED_SHAREDCACHE (SQLITE_LOCKED | (1<<8) ) 453 454/* 455** CAPI3REF: Flags For File Open Operations 456** 457** These bit values are intended for use in the 458** 3rd parameter to the [sqlite3_open_v2()] interface and 459** in the 4th parameter to the xOpen method of the 460** [sqlite3_vfs] object. 461*/ 462#define SQLITE_OPEN_READONLY 0x00000001 /* Ok for sqlite3_open_v2() */ 463#define SQLITE_OPEN_READWRITE 0x00000002 /* Ok for sqlite3_open_v2() */ 464#define SQLITE_OPEN_CREATE 0x00000004 /* Ok for sqlite3_open_v2() */ 465#define SQLITE_OPEN_DELETEONCLOSE 0x00000008 /* VFS only */ 466#define SQLITE_OPEN_EXCLUSIVE 0x00000010 /* VFS only */ 467#define SQLITE_OPEN_AUTOPROXY 0x00000020 /* VFS only */ 468#define SQLITE_OPEN_MAIN_DB 0x00000100 /* VFS only */ 469#define SQLITE_OPEN_TEMP_DB 0x00000200 /* VFS only */ 470#define SQLITE_OPEN_TRANSIENT_DB 0x00000400 /* VFS only */ 471#define SQLITE_OPEN_MAIN_JOURNAL 0x00000800 /* VFS only */ 472#define SQLITE_OPEN_TEMP_JOURNAL 0x00001000 /* VFS only */ 473#define SQLITE_OPEN_SUBJOURNAL 0x00002000 /* VFS only */ 474#define SQLITE_OPEN_MASTER_JOURNAL 0x00004000 /* VFS only */ 475#define SQLITE_OPEN_NOMUTEX 0x00008000 /* Ok for sqlite3_open_v2() */ 476#define SQLITE_OPEN_FULLMUTEX 0x00010000 /* Ok for sqlite3_open_v2() */ 477#define SQLITE_OPEN_SHAREDCACHE 0x00020000 /* Ok for sqlite3_open_v2() */ 478#define SQLITE_OPEN_PRIVATECACHE 0x00040000 /* Ok for sqlite3_open_v2() */ 479 480/* 481** CAPI3REF: Device Characteristics 482** 483** The xDeviceCapabilities method of the [sqlite3_io_methods] 484** object returns an integer which is a vector of the these 485** bit values expressing I/O characteristics of the mass storage 486** device that holds the file that the [sqlite3_io_methods] 487** refers to. 488** 489** The SQLITE_IOCAP_ATOMIC property means that all writes of 490** any size are atomic. The SQLITE_IOCAP_ATOMICnnn values 491** mean that writes of blocks that are nnn bytes in size and 492** are aligned to an address which is an integer multiple of 493** nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means 494** that when data is appended to a file, the data is appended 495** first then the size of the file is extended, never the other 496** way around. The SQLITE_IOCAP_SEQUENTIAL property means that 497** information is written to disk in the same order as calls 498** to xWrite(). 499*/ 500#define SQLITE_IOCAP_ATOMIC 0x00000001 501#define SQLITE_IOCAP_ATOMIC512 0x00000002 502#define SQLITE_IOCAP_ATOMIC1K 0x00000004 503#define SQLITE_IOCAP_ATOMIC2K 0x00000008 504#define SQLITE_IOCAP_ATOMIC4K 0x00000010 505#define SQLITE_IOCAP_ATOMIC8K 0x00000020 506#define SQLITE_IOCAP_ATOMIC16K 0x00000040 507#define SQLITE_IOCAP_ATOMIC32K 0x00000080 508#define SQLITE_IOCAP_ATOMIC64K 0x00000100 509#define SQLITE_IOCAP_SAFE_APPEND 0x00000200 510#define SQLITE_IOCAP_SEQUENTIAL 0x00000400 511 512/* 513** CAPI3REF: File Locking Levels 514** 515** SQLite uses one of these integer values as the second 516** argument to calls it makes to the xLock() and xUnlock() methods 517** of an [sqlite3_io_methods] object. 518*/ 519#define SQLITE_LOCK_NONE 0 520#define SQLITE_LOCK_SHARED 1 521#define SQLITE_LOCK_RESERVED 2 522#define SQLITE_LOCK_PENDING 3 523#define SQLITE_LOCK_EXCLUSIVE 4 524 525/* 526** CAPI3REF: Synchronization Type Flags 527** 528** When SQLite invokes the xSync() method of an 529** [sqlite3_io_methods] object it uses a combination of 530** these integer values as the second argument. 531** 532** When the SQLITE_SYNC_DATAONLY flag is used, it means that the 533** sync operation only needs to flush data to mass storage. Inode 534** information need not be flushed. If the lower four bits of the flag 535** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics. 536** If the lower four bits equal SQLITE_SYNC_FULL, that means 537** to use Mac OS X style fullsync instead of fsync(). 538*/ 539#define SQLITE_SYNC_NORMAL 0x00002 540#define SQLITE_SYNC_FULL 0x00003 541#define SQLITE_SYNC_DATAONLY 0x00010 542 543/* 544** CAPI3REF: OS Interface Open File Handle 545** 546** An [sqlite3_file] object represents an open file in the 547** [sqlite3_vfs | OS interface layer]. Individual OS interface 548** implementations will 549** want to subclass this object by appending additional fields 550** for their own use. The pMethods entry is a pointer to an 551** [sqlite3_io_methods] object that defines methods for performing 552** I/O operations on the open file. 553*/ 554typedef struct sqlite3_file sqlite3_file; 555struct sqlite3_file { 556 const struct sqlite3_io_methods *pMethods; /* Methods for an open file */ 557}; 558 559/* 560** CAPI3REF: OS Interface File Virtual Methods Object 561** 562** Every file opened by the [sqlite3_vfs] xOpen method populates an 563** [sqlite3_file] object (or, more commonly, a subclass of the 564** [sqlite3_file] object) with a pointer to an instance of this object. 565** This object defines the methods used to perform various operations 566** against the open file represented by the [sqlite3_file] object. 567** 568** If the xOpen method sets the sqlite3_file.pMethods element 569** to a non-NULL pointer, then the sqlite3_io_methods.xClose method 570** may be invoked even if the xOpen reported that it failed. The 571** only way to prevent a call to xClose following a failed xOpen 572** is for the xOpen to set the sqlite3_file.pMethods element to NULL. 573** 574** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or 575** [SQLITE_SYNC_FULL]. The first choice is the normal fsync(). 576** The second choice is a Mac OS X style fullsync. The [SQLITE_SYNC_DATAONLY] 577** flag may be ORed in to indicate that only the data of the file 578** and not its inode needs to be synced. 579** 580** The integer values to xLock() and xUnlock() are one of 581** <ul> 582** <li> [SQLITE_LOCK_NONE], 583** <li> [SQLITE_LOCK_SHARED], 584** <li> [SQLITE_LOCK_RESERVED], 585** <li> [SQLITE_LOCK_PENDING], or 586** <li> [SQLITE_LOCK_EXCLUSIVE]. 587** </ul> 588** xLock() increases the lock. xUnlock() decreases the lock. 589** The xCheckReservedLock() method checks whether any database connection, 590** either in this process or in some other process, is holding a RESERVED, 591** PENDING, or EXCLUSIVE lock on the file. It returns true 592** if such a lock exists and false otherwise. 593** 594** The xFileControl() method is a generic interface that allows custom 595** VFS implementations to directly control an open file using the 596** [sqlite3_file_control()] interface. The second "op" argument is an 597** integer opcode. The third argument is a generic pointer intended to 598** point to a structure that may contain arguments or space in which to 599** write return values. Potential uses for xFileControl() might be 600** functions to enable blocking locks with timeouts, to change the 601** locking strategy (for example to use dot-file locks), to inquire 602** about the status of a lock, or to break stale locks. The SQLite 603** core reserves all opcodes less than 100 for its own use. 604** A [SQLITE_FCNTL_LOCKSTATE | list of opcodes] less than 100 is available. 605** Applications that define a custom xFileControl method should use opcodes 606** greater than 100 to avoid conflicts. 607** 608** The xSectorSize() method returns the sector size of the 609** device that underlies the file. The sector size is the 610** minimum write that can be performed without disturbing 611** other bytes in the file. The xDeviceCharacteristics() 612** method returns a bit vector describing behaviors of the 613** underlying device: 614** 615** <ul> 616** <li> [SQLITE_IOCAP_ATOMIC] 617** <li> [SQLITE_IOCAP_ATOMIC512] 618** <li> [SQLITE_IOCAP_ATOMIC1K] 619** <li> [SQLITE_IOCAP_ATOMIC2K] 620** <li> [SQLITE_IOCAP_ATOMIC4K] 621** <li> [SQLITE_IOCAP_ATOMIC8K] 622** <li> [SQLITE_IOCAP_ATOMIC16K] 623** <li> [SQLITE_IOCAP_ATOMIC32K] 624** <li> [SQLITE_IOCAP_ATOMIC64K] 625** <li> [SQLITE_IOCAP_SAFE_APPEND] 626** <li> [SQLITE_IOCAP_SEQUENTIAL] 627** </ul> 628** 629** The SQLITE_IOCAP_ATOMIC property means that all writes of 630** any size are atomic. The SQLITE_IOCAP_ATOMICnnn values 631** mean that writes of blocks that are nnn bytes in size and 632** are aligned to an address which is an integer multiple of 633** nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means 634** that when data is appended to a file, the data is appended 635** first then the size of the file is extended, never the other 636** way around. The SQLITE_IOCAP_SEQUENTIAL property means that 637** information is written to disk in the same order as calls 638** to xWrite(). 639** 640** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill 641** in the unread portions of the buffer with zeros. A VFS that 642** fails to zero-fill short reads might seem to work. However, 643** failure to zero-fill short reads will eventually lead to 644** database corruption. 645*/ 646typedef struct sqlite3_io_methods sqlite3_io_methods; 647struct sqlite3_io_methods { 648 int iVersion; 649 int (*xClose)(sqlite3_file*); 650 int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst); 651 int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst); 652 int (*xTruncate)(sqlite3_file*, sqlite3_int64 size); 653 int (*xSync)(sqlite3_file*, int flags); 654 int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize); 655 int (*xLock)(sqlite3_file*, int); 656 int (*xUnlock)(sqlite3_file*, int); 657 int (*xCheckReservedLock)(sqlite3_file*, int *pResOut); 658 int (*xFileControl)(sqlite3_file*, int op, void *pArg); 659 int (*xSectorSize)(sqlite3_file*); 660 int (*xDeviceCharacteristics)(sqlite3_file*); 661 /* Additional methods may be added in future releases */ 662}; 663 664/* 665** CAPI3REF: Standard File Control Opcodes 666** 667** These integer constants are opcodes for the xFileControl method 668** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()] 669** interface. 670** 671** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging. This 672** opcode causes the xFileControl method to write the current state of 673** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED], 674** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE]) 675** into an integer that the pArg argument points to. This capability 676** is used during testing and only needs to be supported when SQLITE_TEST 677** is defined. 678*/ 679#define SQLITE_FCNTL_LOCKSTATE 1 680#define SQLITE_GET_LOCKPROXYFILE 2 681#define SQLITE_SET_LOCKPROXYFILE 3 682#define SQLITE_LAST_ERRNO 4 683 684/* 685** CAPI3REF: Mutex Handle 686** 687** The mutex module within SQLite defines [sqlite3_mutex] to be an 688** abstract type for a mutex object. The SQLite core never looks 689** at the internal representation of an [sqlite3_mutex]. It only 690** deals with pointers to the [sqlite3_mutex] object. 691** 692** Mutexes are created using [sqlite3_mutex_alloc()]. 693*/ 694typedef struct sqlite3_mutex sqlite3_mutex; 695 696/* 697** CAPI3REF: OS Interface Object 698** 699** An instance of the sqlite3_vfs object defines the interface between 700** the SQLite core and the underlying operating system. The "vfs" 701** in the name of the object stands for "virtual file system". 702** 703** The value of the iVersion field is initially 1 but may be larger in 704** future versions of SQLite. Additional fields may be appended to this 705** object when the iVersion value is increased. Note that the structure 706** of the sqlite3_vfs object changes in the transaction between 707** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not 708** modified. 709** 710** The szOsFile field is the size of the subclassed [sqlite3_file] 711** structure used by this VFS. mxPathname is the maximum length of 712** a pathname in this VFS. 713** 714** Registered sqlite3_vfs objects are kept on a linked list formed by 715** the pNext pointer. The [sqlite3_vfs_register()] 716** and [sqlite3_vfs_unregister()] interfaces manage this list 717** in a thread-safe way. The [sqlite3_vfs_find()] interface 718** searches the list. Neither the application code nor the VFS 719** implementation should use the pNext pointer. 720** 721** The pNext field is the only field in the sqlite3_vfs 722** structure that SQLite will ever modify. SQLite will only access 723** or modify this field while holding a particular static mutex. 724** The application should never modify anything within the sqlite3_vfs 725** object once the object has been registered. 726** 727** The zName field holds the name of the VFS module. The name must 728** be unique across all VFS modules. 729** 730** SQLite will guarantee that the zFilename parameter to xOpen 731** is either a NULL pointer or string obtained 732** from xFullPathname(). SQLite further guarantees that 733** the string will be valid and unchanged until xClose() is 734** called. Because of the previous sentence, 735** the [sqlite3_file] can safely store a pointer to the 736** filename if it needs to remember the filename for some reason. 737** If the zFilename parameter is xOpen is a NULL pointer then xOpen 738** must invent its own temporary name for the file. Whenever the 739** xFilename parameter is NULL it will also be the case that the 740** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE]. 741** 742** The flags argument to xOpen() includes all bits set in 743** the flags argument to [sqlite3_open_v2()]. Or if [sqlite3_open()] 744** or [sqlite3_open16()] is used, then flags includes at least 745** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]. 746** If xOpen() opens a file read-only then it sets *pOutFlags to 747** include [SQLITE_OPEN_READONLY]. Other bits in *pOutFlags may be set. 748** 749** SQLite will also add one of the following flags to the xOpen() 750** call, depending on the object being opened: 751** 752** <ul> 753** <li> [SQLITE_OPEN_MAIN_DB] 754** <li> [SQLITE_OPEN_MAIN_JOURNAL] 755** <li> [SQLITE_OPEN_TEMP_DB] 756** <li> [SQLITE_OPEN_TEMP_JOURNAL] 757** <li> [SQLITE_OPEN_TRANSIENT_DB] 758** <li> [SQLITE_OPEN_SUBJOURNAL] 759** <li> [SQLITE_OPEN_MASTER_JOURNAL] 760** </ul> 761** 762** The file I/O implementation can use the object type flags to 763** change the way it deals with files. For example, an application 764** that does not care about crash recovery or rollback might make 765** the open of a journal file a no-op. Writes to this journal would 766** also be no-ops, and any attempt to read the journal would return 767** SQLITE_IOERR. Or the implementation might recognize that a database 768** file will be doing page-aligned sector reads and writes in a random 769** order and set up its I/O subsystem accordingly. 770** 771** SQLite might also add one of the following flags to the xOpen method: 772** 773** <ul> 774** <li> [SQLITE_OPEN_DELETEONCLOSE] 775** <li> [SQLITE_OPEN_EXCLUSIVE] 776** </ul> 777** 778** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be 779** deleted when it is closed. The [SQLITE_OPEN_DELETEONCLOSE] 780** will be set for TEMP databases, journals and for subjournals. 781** 782** The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction 783** with the [SQLITE_OPEN_CREATE] flag, which are both directly 784** analogous to the O_EXCL and O_CREAT flags of the POSIX open() 785** API. The SQLITE_OPEN_EXCLUSIVE flag, when paired with the 786** SQLITE_OPEN_CREATE, is used to indicate that file should always 787** be created, and that it is an error if it already exists. 788** It is <i>not</i> used to indicate the file should be opened 789** for exclusive access. 790** 791** At least szOsFile bytes of memory are allocated by SQLite 792** to hold the [sqlite3_file] structure passed as the third 793** argument to xOpen. The xOpen method does not have to 794** allocate the structure; it should just fill it in. Note that 795** the xOpen method must set the sqlite3_file.pMethods to either 796** a valid [sqlite3_io_methods] object or to NULL. xOpen must do 797** this even if the open fails. SQLite expects that the sqlite3_file.pMethods 798** element will be valid after xOpen returns regardless of the success 799** or failure of the xOpen call. 800** 801** The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS] 802** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to 803** test whether a file is readable and writable, or [SQLITE_ACCESS_READ] 804** to test whether a file is at least readable. The file can be a 805** directory. 806** 807** SQLite will always allocate at least mxPathname+1 bytes for the 808** output buffer xFullPathname. The exact size of the output buffer 809** is also passed as a parameter to both methods. If the output buffer 810** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is 811** handled as a fatal error by SQLite, vfs implementations should endeavor 812** to prevent this by setting mxPathname to a sufficiently large value. 813** 814** The xRandomness(), xSleep(), and xCurrentTime() interfaces 815** are not strictly a part of the filesystem, but they are 816** included in the VFS structure for completeness. 817** The xRandomness() function attempts to return nBytes bytes 818** of good-quality randomness into zOut. The return value is 819** the actual number of bytes of randomness obtained. 820** The xSleep() method causes the calling thread to sleep for at 821** least the number of microseconds given. The xCurrentTime() 822** method returns a Julian Day Number for the current date and time. 823** 824*/ 825typedef struct sqlite3_vfs sqlite3_vfs; 826struct sqlite3_vfs { 827 int iVersion; /* Structure version number */ 828 int szOsFile; /* Size of subclassed sqlite3_file */ 829 int mxPathname; /* Maximum file pathname length */ 830 sqlite3_vfs *pNext; /* Next registered VFS */ 831 const char *zName; /* Name of this virtual file system */ 832 void *pAppData; /* Pointer to application-specific data */ 833 int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*, 834 int flags, int *pOutFlags); 835 int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir); 836 int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut); 837 int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut); 838 void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename); 839 void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg); 840 void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void); 841 void (*xDlClose)(sqlite3_vfs*, void*); 842 int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut); 843 int (*xSleep)(sqlite3_vfs*, int microseconds); 844 int (*xCurrentTime)(sqlite3_vfs*, double*); 845 int (*xGetLastError)(sqlite3_vfs*, int, char *); 846 /* New fields may be appended in figure versions. The iVersion 847 ** value will increment whenever this happens. */ 848}; 849 850/* 851** CAPI3REF: Flags for the xAccess VFS method 852** 853** These integer constants can be used as the third parameter to 854** the xAccess method of an [sqlite3_vfs] object. They determine 855** what kind of permissions the xAccess method is looking for. 856** With SQLITE_ACCESS_EXISTS, the xAccess method 857** simply checks whether the file exists. 858** With SQLITE_ACCESS_READWRITE, the xAccess method 859** checks whether the file is both readable and writable. 860** With SQLITE_ACCESS_READ, the xAccess method 861** checks whether the file is readable. 862*/ 863#define SQLITE_ACCESS_EXISTS 0 864#define SQLITE_ACCESS_READWRITE 1 865#define SQLITE_ACCESS_READ 2 866 867/* 868** CAPI3REF: Initialize The SQLite Library 869** 870** ^The sqlite3_initialize() routine initializes the 871** SQLite library. ^The sqlite3_shutdown() routine 872** deallocates any resources that were allocated by sqlite3_initialize(). 873** These routines are designed to aid in process initialization and 874** shutdown on embedded systems. Workstation applications using 875** SQLite normally do not need to invoke either of these routines. 876** 877** A call to sqlite3_initialize() is an "effective" call if it is 878** the first time sqlite3_initialize() is invoked during the lifetime of 879** the process, or if it is the first time sqlite3_initialize() is invoked 880** following a call to sqlite3_shutdown(). ^(Only an effective call 881** of sqlite3_initialize() does any initialization. All other calls 882** are harmless no-ops.)^ 883** 884** A call to sqlite3_shutdown() is an "effective" call if it is the first 885** call to sqlite3_shutdown() since the last sqlite3_initialize(). ^(Only 886** an effective call to sqlite3_shutdown() does any deinitialization. 887** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^ 888** 889** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown() 890** is not. The sqlite3_shutdown() interface must only be called from a 891** single thread. All open [database connections] must be closed and all 892** other SQLite resources must be deallocated prior to invoking 893** sqlite3_shutdown(). 894** 895** Among other things, ^sqlite3_initialize() will invoke 896** sqlite3_os_init(). Similarly, ^sqlite3_shutdown() 897** will invoke sqlite3_os_end(). 898** 899** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success. 900** ^If for some reason, sqlite3_initialize() is unable to initialize 901** the library (perhaps it is unable to allocate a needed resource such 902** as a mutex) it returns an [error code] other than [SQLITE_OK]. 903** 904** ^The sqlite3_initialize() routine is called internally by many other 905** SQLite interfaces so that an application usually does not need to 906** invoke sqlite3_initialize() directly. For example, [sqlite3_open()] 907** calls sqlite3_initialize() so the SQLite library will be automatically 908** initialized when [sqlite3_open()] is called if it has not be initialized 909** already. ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT] 910** compile-time option, then the automatic calls to sqlite3_initialize() 911** are omitted and the application must call sqlite3_initialize() directly 912** prior to using any other SQLite interface. For maximum portability, 913** it is recommended that applications always invoke sqlite3_initialize() 914** directly prior to using any other SQLite interface. Future releases 915** of SQLite may require this. In other words, the behavior exhibited 916** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the 917** default behavior in some future release of SQLite. 918** 919** The sqlite3_os_init() routine does operating-system specific 920** initialization of the SQLite library. The sqlite3_os_end() 921** routine undoes the effect of sqlite3_os_init(). Typical tasks 922** performed by these routines include allocation or deallocation 923** of static resources, initialization of global variables, 924** setting up a default [sqlite3_vfs] module, or setting up 925** a default configuration using [sqlite3_config()]. 926** 927** The application should never invoke either sqlite3_os_init() 928** or sqlite3_os_end() directly. The application should only invoke 929** sqlite3_initialize() and sqlite3_shutdown(). The sqlite3_os_init() 930** interface is called automatically by sqlite3_initialize() and 931** sqlite3_os_end() is called by sqlite3_shutdown(). Appropriate 932** implementations for sqlite3_os_init() and sqlite3_os_end() 933** are built into SQLite when it is compiled for Unix, Windows, or OS/2. 934** When [custom builds | built for other platforms] 935** (using the [SQLITE_OS_OTHER=1] compile-time 936** option) the application must supply a suitable implementation for 937** sqlite3_os_init() and sqlite3_os_end(). An application-supplied 938** implementation of sqlite3_os_init() or sqlite3_os_end() 939** must return [SQLITE_OK] on success and some other [error code] upon 940** failure. 941*/ 942SQLITE_API int sqlite3_initialize(void); 943SQLITE_API int sqlite3_shutdown(void); 944SQLITE_API int sqlite3_os_init(void); 945SQLITE_API int sqlite3_os_end(void); 946 947/* 948** CAPI3REF: Configuring The SQLite Library 949** 950** The sqlite3_config() interface is used to make global configuration 951** changes to SQLite in order to tune SQLite to the specific needs of 952** the application. The default configuration is recommended for most 953** applications and so this routine is usually not necessary. It is 954** provided to support rare applications with unusual needs. 955** 956** The sqlite3_config() interface is not threadsafe. The application 957** must insure that no other SQLite interfaces are invoked by other 958** threads while sqlite3_config() is running. Furthermore, sqlite3_config() 959** may only be invoked prior to library initialization using 960** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()]. 961** ^If sqlite3_config() is called after [sqlite3_initialize()] and before 962** [sqlite3_shutdown()] then it will return SQLITE_MISUSE. 963** Note, however, that ^sqlite3_config() can be called as part of the 964** implementation of an application-defined [sqlite3_os_init()]. 965** 966** The first argument to sqlite3_config() is an integer 967** [SQLITE_CONFIG_SINGLETHREAD | configuration option] that determines 968** what property of SQLite is to be configured. Subsequent arguments 969** vary depending on the [SQLITE_CONFIG_SINGLETHREAD | configuration option] 970** in the first argument. 971** 972** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK]. 973** ^If the option is unknown or SQLite is unable to set the option 974** then this routine returns a non-zero [error code]. 975*/ 976SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_config(int, ...); 977 978/* 979** CAPI3REF: Configure database connections 980** EXPERIMENTAL 981** 982** The sqlite3_db_config() interface is used to make configuration 983** changes to a [database connection]. The interface is similar to 984** [sqlite3_config()] except that the changes apply to a single 985** [database connection] (specified in the first argument). The 986** sqlite3_db_config() interface should only be used immediately after 987** the database connection is created using [sqlite3_open()], 988** [sqlite3_open16()], or [sqlite3_open_v2()]. 989** 990** The second argument to sqlite3_db_config(D,V,...) is the 991** configuration verb - an integer code that indicates what 992** aspect of the [database connection] is being configured. 993** The only choice for this value is [SQLITE_DBCONFIG_LOOKASIDE]. 994** New verbs are likely to be added in future releases of SQLite. 995** Additional arguments depend on the verb. 996** 997** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if 998** the call is considered successful. 999*/ 1000SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_db_config(sqlite3*, int op, ...); 1001 1002/* 1003** CAPI3REF: Memory Allocation Routines 1004** EXPERIMENTAL 1005** 1006** An instance of this object defines the interface between SQLite 1007** and low-level memory allocation routines. 1008** 1009** This object is used in only one place in the SQLite interface. 1010** A pointer to an instance of this object is the argument to 1011** [sqlite3_config()] when the configuration option is 1012** [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC]. 1013** By creating an instance of this object 1014** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC]) 1015** during configuration, an application can specify an alternative 1016** memory allocation subsystem for SQLite to use for all of its 1017** dynamic memory needs. 1018** 1019** Note that SQLite comes with several [built-in memory allocators] 1020** that are perfectly adequate for the overwhelming majority of applications 1021** and that this object is only useful to a tiny minority of applications 1022** with specialized memory allocation requirements. This object is 1023** also used during testing of SQLite in order to specify an alternative 1024** memory allocator that simulates memory out-of-memory conditions in 1025** order to verify that SQLite recovers gracefully from such 1026** conditions. 1027** 1028** The xMalloc and xFree methods must work like the 1029** malloc() and free() functions from the standard C library. 1030** The xRealloc method must work like realloc() from the standard C library 1031** with the exception that if the second argument to xRealloc is zero, 1032** xRealloc must be a no-op - it must not perform any allocation or 1033** deallocation. ^SQLite guarantees that the second argument to 1034** xRealloc is always a value returned by a prior call to xRoundup. 1035** And so in cases where xRoundup always returns a positive number, 1036** xRealloc can perform exactly as the standard library realloc() and 1037** still be in compliance with this specification. 1038** 1039** xSize should return the allocated size of a memory allocation 1040** previously obtained from xMalloc or xRealloc. The allocated size 1041** is always at least as big as the requested size but may be larger. 1042** 1043** The xRoundup method returns what would be the allocated size of 1044** a memory allocation given a particular requested size. Most memory 1045** allocators round up memory allocations at least to the next multiple 1046** of 8. Some allocators round up to a larger multiple or to a power of 2. 1047** Every memory allocation request coming in through [sqlite3_malloc()] 1048** or [sqlite3_realloc()] first calls xRoundup. If xRoundup returns 0, 1049** that causes the corresponding memory allocation to fail. 1050** 1051** The xInit method initializes the memory allocator. (For example, 1052** it might allocate any require mutexes or initialize internal data 1053** structures. The xShutdown method is invoked (indirectly) by 1054** [sqlite3_shutdown()] and should deallocate any resources acquired 1055** by xInit. The pAppData pointer is used as the only parameter to 1056** xInit and xShutdown. 1057** 1058** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes 1059** the xInit method, so the xInit method need not be threadsafe. The 1060** xShutdown method is only called from [sqlite3_shutdown()] so it does 1061** not need to be threadsafe either. For all other methods, SQLite 1062** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the 1063** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which 1064** it is by default) and so the methods are automatically serialized. 1065** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other 1066** methods must be threadsafe or else make their own arrangements for 1067** serialization. 1068** 1069** SQLite will never invoke xInit() more than once without an intervening 1070** call to xShutdown(). 1071*/ 1072typedef struct sqlite3_mem_methods sqlite3_mem_methods; 1073struct sqlite3_mem_methods { 1074 void *(*xMalloc)(int); /* Memory allocation function */ 1075 void (*xFree)(void*); /* Free a prior allocation */ 1076 void *(*xRealloc)(void*,int); /* Resize an allocation */ 1077 int (*xSize)(void*); /* Return the size of an allocation */ 1078 int (*xRoundup)(int); /* Round up request size to allocation size */ 1079 int (*xInit)(void*); /* Initialize the memory allocator */ 1080 void (*xShutdown)(void*); /* Deinitialize the memory allocator */ 1081 void *pAppData; /* Argument to xInit() and xShutdown() */ 1082}; 1083 1084/* 1085** CAPI3REF: Configuration Options 1086** EXPERIMENTAL 1087** 1088** These constants are the available integer configuration options that 1089** can be passed as the first argument to the [sqlite3_config()] interface. 1090** 1091** New configuration options may be added in future releases of SQLite. 1092** Existing configuration options might be discontinued. Applications 1093** should check the return code from [sqlite3_config()] to make sure that 1094** the call worked. The [sqlite3_config()] interface will return a 1095** non-zero [error code] if a discontinued or unsupported configuration option 1096** is invoked. 1097** 1098** <dl> 1099** <dt>SQLITE_CONFIG_SINGLETHREAD</dt> 1100** <dd>There are no arguments to this option. ^This option sets the 1101** [threading mode] to Single-thread. In other words, it disables 1102** all mutexing and puts SQLite into a mode where it can only be used 1103** by a single thread. ^If SQLite is compiled with 1104** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then 1105** it is not possible to change the [threading mode] from its default 1106** value of Single-thread and so [sqlite3_config()] will return 1107** [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD 1108** configuration option.</dd> 1109** 1110** <dt>SQLITE_CONFIG_MULTITHREAD</dt> 1111** <dd>There are no arguments to this option. ^This option sets the 1112** [threading mode] to Multi-thread. In other words, it disables 1113** mutexing on [database connection] and [prepared statement] objects. 1114** The application is responsible for serializing access to 1115** [database connections] and [prepared statements]. But other mutexes 1116** are enabled so that SQLite will be safe to use in a multi-threaded 1117** environment as long as no two threads attempt to use the same 1118** [database connection] at the same time. ^If SQLite is compiled with 1119** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then 1120** it is not possible to set the Multi-thread [threading mode] and 1121** [sqlite3_config()] will return [SQLITE_ERROR] if called with the 1122** SQLITE_CONFIG_MULTITHREAD configuration option.</dd> 1123** 1124** <dt>SQLITE_CONFIG_SERIALIZED</dt> 1125** <dd>There are no arguments to this option. ^This option sets the 1126** [threading mode] to Serialized. In other words, this option enables 1127** all mutexes including the recursive 1128** mutexes on [database connection] and [prepared statement] objects. 1129** In this mode (which is the default when SQLite is compiled with 1130** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access 1131** to [database connections] and [prepared statements] so that the 1132** application is free to use the same [database connection] or the 1133** same [prepared statement] in different threads at the same time. 1134** ^If SQLite is compiled with 1135** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then 1136** it is not possible to set the Serialized [threading mode] and 1137** [sqlite3_config()] will return [SQLITE_ERROR] if called with the 1138** SQLITE_CONFIG_SERIALIZED configuration option.</dd> 1139** 1140** <dt>SQLITE_CONFIG_MALLOC</dt> 1141** <dd> ^(This option takes a single argument which is a pointer to an 1142** instance of the [sqlite3_mem_methods] structure. The argument specifies 1143** alternative low-level memory allocation routines to be used in place of 1144** the memory allocation routines built into SQLite.)^ ^SQLite makes 1145** its own private copy of the content of the [sqlite3_mem_methods] structure 1146** before the [sqlite3_config()] call returns.</dd> 1147** 1148** <dt>SQLITE_CONFIG_GETMALLOC</dt> 1149** <dd> ^(This option takes a single argument which is a pointer to an 1150** instance of the [sqlite3_mem_methods] structure. The [sqlite3_mem_methods] 1151** structure is filled with the currently defined memory allocation routines.)^ 1152** This option can be used to overload the default memory allocation 1153** routines with a wrapper that simulations memory allocation failure or 1154** tracks memory usage, for example. </dd> 1155** 1156** <dt>SQLITE_CONFIG_MEMSTATUS</dt> 1157** <dd> ^This option takes single argument of type int, interpreted as a 1158** boolean, which enables or disables the collection of memory allocation 1159** statistics. ^(When memory allocation statistics are disabled, the 1160** following SQLite interfaces become non-operational: 1161** <ul> 1162** <li> [sqlite3_memory_used()] 1163** <li> [sqlite3_memory_highwater()] 1164** <li> [sqlite3_soft_heap_limit()] 1165** <li> [sqlite3_status()] 1166** </ul>)^ 1167** ^Memory allocation statistics are enabled by default unless SQLite is 1168** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory 1169** allocation statistics are disabled by default. 1170** </dd> 1171** 1172** <dt>SQLITE_CONFIG_SCRATCH</dt> 1173** <dd> ^This option specifies a static memory buffer that SQLite can use for 1174** scratch memory. There are three arguments: A pointer an 8-byte 1175** aligned memory buffer from which the scrach allocations will be 1176** drawn, the size of each scratch allocation (sz), 1177** and the maximum number of scratch allocations (N). The sz 1178** argument must be a multiple of 16. The sz parameter should be a few bytes 1179** larger than the actual scratch space required due to internal overhead. 1180** The first argument must be a pointer to an 8-byte aligned buffer 1181** of at least sz*N bytes of memory. 1182** ^SQLite will use no more than one scratch buffer per thread. So 1183** N should be set to the expected maximum number of threads. ^SQLite will 1184** never require a scratch buffer that is more than 6 times the database 1185** page size. ^If SQLite needs needs additional scratch memory beyond 1186** what is provided by this configuration option, then 1187** [sqlite3_malloc()] will be used to obtain the memory needed.</dd> 1188** 1189** <dt>SQLITE_CONFIG_PAGECACHE</dt> 1190** <dd> ^This option specifies a static memory buffer that SQLite can use for 1191** the database page cache with the default page cache implemenation. 1192** This configuration should not be used if an application-define page 1193** cache implementation is loaded using the SQLITE_CONFIG_PCACHE option. 1194** There are three arguments to this option: A pointer to 8-byte aligned 1195** memory, the size of each page buffer (sz), and the number of pages (N). 1196** The sz argument should be the size of the largest database page 1197** (a power of two between 512 and 32768) plus a little extra for each 1198** page header. ^The page header size is 20 to 40 bytes depending on 1199** the host architecture. ^It is harmless, apart from the wasted memory, 1200** to make sz a little too large. The first 1201** argument should point to an allocation of at least sz*N bytes of memory. 1202** ^SQLite will use the memory provided by the first argument to satisfy its 1203** memory needs for the first N pages that it adds to cache. ^If additional 1204** page cache memory is needed beyond what is provided by this option, then 1205** SQLite goes to [sqlite3_malloc()] for the additional storage space. 1206** ^The implementation might use one or more of the N buffers to hold 1207** memory accounting information. The pointer in the first argument must 1208** be aligned to an 8-byte boundary or subsequent behavior of SQLite 1209** will be undefined.</dd> 1210** 1211** <dt>SQLITE_CONFIG_HEAP</dt> 1212** <dd> ^This option specifies a static memory buffer that SQLite will use 1213** for all of its dynamic memory allocation needs beyond those provided 1214** for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE]. 1215** There are three arguments: An 8-byte aligned pointer to the memory, 1216** the number of bytes in the memory buffer, and the minimum allocation size. 1217** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts 1218** to using its default memory allocator (the system malloc() implementation), 1219** undoing any prior invocation of [SQLITE_CONFIG_MALLOC]. ^If the 1220** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or 1221** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory 1222** allocator is engaged to handle all of SQLites memory allocation needs. 1223** The first pointer (the memory pointer) must be aligned to an 8-byte 1224** boundary or subsequent behavior of SQLite will be undefined.</dd> 1225** 1226** <dt>SQLITE_CONFIG_MUTEX</dt> 1227** <dd> ^(This option takes a single argument which is a pointer to an 1228** instance of the [sqlite3_mutex_methods] structure. The argument specifies 1229** alternative low-level mutex routines to be used in place 1230** the mutex routines built into SQLite.)^ ^SQLite makes a copy of the 1231** content of the [sqlite3_mutex_methods] structure before the call to 1232** [sqlite3_config()] returns. ^If SQLite is compiled with 1233** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then 1234** the entire mutexing subsystem is omitted from the build and hence calls to 1235** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will 1236** return [SQLITE_ERROR].</dd> 1237** 1238** <dt>SQLITE_CONFIG_GETMUTEX</dt> 1239** <dd> ^(This option takes a single argument which is a pointer to an 1240** instance of the [sqlite3_mutex_methods] structure. The 1241** [sqlite3_mutex_methods] 1242** structure is filled with the currently defined mutex routines.)^ 1243** This option can be used to overload the default mutex allocation 1244** routines with a wrapper used to track mutex usage for performance 1245** profiling or testing, for example. ^If SQLite is compiled with 1246** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then 1247** the entire mutexing subsystem is omitted from the build and hence calls to 1248** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will 1249** return [SQLITE_ERROR].</dd> 1250** 1251** <dt>SQLITE_CONFIG_LOOKASIDE</dt> 1252** <dd> ^(This option takes two arguments that determine the default 1253** memory allocation for the lookaside memory allocator on each 1254** [database connection]. The first argument is the 1255** size of each lookaside buffer slot and the second is the number of 1256** slots allocated to each database connection.)^ ^(This option sets the 1257** <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE] 1258** verb to [sqlite3_db_config()] can be used to change the lookaside 1259** configuration on individual connections.)^ </dd> 1260** 1261** <dt>SQLITE_CONFIG_PCACHE</dt> 1262** <dd> ^(This option takes a single argument which is a pointer to 1263** an [sqlite3_pcache_methods] object. This object specifies the interface 1264** to a custom page cache implementation.)^ ^SQLite makes a copy of the 1265** object and uses it for page cache memory allocations.</dd> 1266** 1267** <dt>SQLITE_CONFIG_GETPCACHE</dt> 1268** <dd> ^(This option takes a single argument which is a pointer to an 1269** [sqlite3_pcache_methods] object. SQLite copies of the current 1270** page cache implementation into that object.)^ </dd> 1271** 1272** </dl> 1273*/ 1274#define SQLITE_CONFIG_SINGLETHREAD 1 /* nil */ 1275#define SQLITE_CONFIG_MULTITHREAD 2 /* nil */ 1276#define SQLITE_CONFIG_SERIALIZED 3 /* nil */ 1277#define SQLITE_CONFIG_MALLOC 4 /* sqlite3_mem_methods* */ 1278#define SQLITE_CONFIG_GETMALLOC 5 /* sqlite3_mem_methods* */ 1279#define SQLITE_CONFIG_SCRATCH 6 /* void*, int sz, int N */ 1280#define SQLITE_CONFIG_PAGECACHE 7 /* void*, int sz, int N */ 1281#define SQLITE_CONFIG_HEAP 8 /* void*, int nByte, int min */ 1282#define SQLITE_CONFIG_MEMSTATUS 9 /* boolean */ 1283#define SQLITE_CONFIG_MUTEX 10 /* sqlite3_mutex_methods* */ 1284#define SQLITE_CONFIG_GETMUTEX 11 /* sqlite3_mutex_methods* */ 1285/* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 1286#define SQLITE_CONFIG_LOOKASIDE 13 /* int int */ 1287#define SQLITE_CONFIG_PCACHE 14 /* sqlite3_pcache_methods* */ 1288#define SQLITE_CONFIG_GETPCACHE 15 /* sqlite3_pcache_methods* */ 1289#define SQLITE_CONFIG_LOG 16 /* xFunc, void* */ 1290 1291/* 1292** CAPI3REF: Configuration Options 1293** EXPERIMENTAL 1294** 1295** These constants are the available integer configuration options that 1296** can be passed as the second argument to the [sqlite3_db_config()] interface. 1297** 1298** New configuration options may be added in future releases of SQLite. 1299** Existing configuration options might be discontinued. Applications 1300** should check the return code from [sqlite3_db_config()] to make sure that 1301** the call worked. ^The [sqlite3_db_config()] interface will return a 1302** non-zero [error code] if a discontinued or unsupported configuration option 1303** is invoked. 1304** 1305** <dl> 1306** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt> 1307** <dd> ^This option takes three additional arguments that determine the 1308** [lookaside memory allocator] configuration for the [database connection]. 1309** ^The first argument (the third parameter to [sqlite3_db_config()] is a 1310** pointer to an memory buffer to use for lookaside memory. 1311** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb 1312** may be NULL in which case SQLite will allocate the 1313** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the 1314** size of each lookaside buffer slot. ^The third argument is the number of 1315** slots. The size of the buffer in the first argument must be greater than 1316** or equal to the product of the second and third arguments. The buffer 1317** must be aligned to an 8-byte boundary. ^If the second argument to 1318** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally 1319** rounded down to the next smaller 1320** multiple of 8. See also: [SQLITE_CONFIG_LOOKASIDE]</dd> 1321** 1322** </dl> 1323*/ 1324#define SQLITE_DBCONFIG_LOOKASIDE 1001 /* void* int int */ 1325 1326 1327/* 1328** CAPI3REF: Enable Or Disable Extended Result Codes 1329** 1330** ^The sqlite3_extended_result_codes() routine enables or disables the 1331** [extended result codes] feature of SQLite. ^The extended result 1332** codes are disabled by default for historical compatibility. 1333*/ 1334SQLITE_API int sqlite3_extended_result_codes(sqlite3*, int onoff); 1335 1336/* 1337** CAPI3REF: Last Insert Rowid 1338** 1339** ^Each entry in an SQLite table has a unique 64-bit signed 1340** integer key called the [ROWID | "rowid"]. ^The rowid is always available 1341** as an undeclared column named ROWID, OID, or _ROWID_ as long as those 1342** names are not also used by explicitly declared columns. ^If 1343** the table has a column of type [INTEGER PRIMARY KEY] then that column 1344** is another alias for the rowid. 1345** 1346** ^This routine returns the [rowid] of the most recent 1347** successful [INSERT] into the database from the [database connection] 1348** in the first argument. ^If no successful [INSERT]s 1349** have ever occurred on that database connection, zero is returned. 1350** 1351** ^(If an [INSERT] occurs within a trigger, then the [rowid] of the inserted 1352** row is returned by this routine as long as the trigger is running. 1353** But once the trigger terminates, the value returned by this routine 1354** reverts to the last value inserted before the trigger fired.)^ 1355** 1356** ^An [INSERT] that fails due to a constraint violation is not a 1357** successful [INSERT] and does not change the value returned by this 1358** routine. ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK, 1359** and INSERT OR ABORT make no changes to the return value of this 1360** routine when their insertion fails. ^(When INSERT OR REPLACE 1361** encounters a constraint violation, it does not fail. The 1362** INSERT continues to completion after deleting rows that caused 1363** the constraint problem so INSERT OR REPLACE will always change 1364** the return value of this interface.)^ 1365** 1366** ^For the purposes of this routine, an [INSERT] is considered to 1367** be successful even if it is subsequently rolled back. 1368** 1369** This function is accessible to SQL statements via the 1370** [last_insert_rowid() SQL function]. 1371** 1372** If a separate thread performs a new [INSERT] on the same 1373** database connection while the [sqlite3_last_insert_rowid()] 1374** function is running and thus changes the last insert [rowid], 1375** then the value returned by [sqlite3_last_insert_rowid()] is 1376** unpredictable and might not equal either the old or the new 1377** last insert [rowid]. 1378*/ 1379SQLITE_API sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*); 1380 1381/* 1382** CAPI3REF: Count The Number Of Rows Modified 1383** 1384** ^This function returns the number of database rows that were changed 1385** or inserted or deleted by the most recently completed SQL statement 1386** on the [database connection] specified by the first parameter. 1387** ^(Only changes that are directly specified by the [INSERT], [UPDATE], 1388** or [DELETE] statement are counted. Auxiliary changes caused by 1389** triggers or [foreign key actions] are not counted.)^ Use the 1390** [sqlite3_total_changes()] function to find the total number of changes 1391** including changes caused by triggers and foreign key actions. 1392** 1393** ^Changes to a view that are simulated by an [INSTEAD OF trigger] 1394** are not counted. Only real table changes are counted. 1395** 1396** ^(A "row change" is a change to a single row of a single table 1397** caused by an INSERT, DELETE, or UPDATE statement. Rows that 1398** are changed as side effects of [REPLACE] constraint resolution, 1399** rollback, ABORT processing, [DROP TABLE], or by any other 1400** mechanisms do not count as direct row changes.)^ 1401** 1402** A "trigger context" is a scope of execution that begins and 1403** ends with the script of a [CREATE TRIGGER | trigger]. 1404** Most SQL statements are 1405** evaluated outside of any trigger. This is the "top level" 1406** trigger context. If a trigger fires from the top level, a 1407** new trigger context is entered for the duration of that one 1408** trigger. Subtriggers create subcontexts for their duration. 1409** 1410** ^Calling [sqlite3_exec()] or [sqlite3_step()] recursively does 1411** not create a new trigger context. 1412** 1413** ^This function returns the number of direct row changes in the 1414** most recent INSERT, UPDATE, or DELETE statement within the same 1415** trigger context. 1416** 1417** ^Thus, when called from the top level, this function returns the 1418** number of changes in the most recent INSERT, UPDATE, or DELETE 1419** that also occurred at the top level. ^(Within the body of a trigger, 1420** the sqlite3_changes() interface can be called to find the number of 1421** changes in the most recently completed INSERT, UPDATE, or DELETE 1422** statement within the body of the same trigger. 1423** However, the number returned does not include changes 1424** caused by subtriggers since those have their own context.)^ 1425** 1426** See also the [sqlite3_total_changes()] interface, the 1427** [count_changes pragma], and the [changes() SQL function]. 1428** 1429** If a separate thread makes changes on the same database connection 1430** while [sqlite3_changes()] is running then the value returned 1431** is unpredictable and not meaningful. 1432*/ 1433SQLITE_API int sqlite3_changes(sqlite3*); 1434 1435/* 1436** CAPI3REF: Total Number Of Rows Modified 1437** 1438** ^This function returns the number of row changes caused by [INSERT], 1439** [UPDATE] or [DELETE] statements since the [database connection] was opened. 1440** ^(The count returned by sqlite3_total_changes() includes all changes 1441** from all [CREATE TRIGGER | trigger] contexts and changes made by 1442** [foreign key actions]. However, 1443** the count does not include changes used to implement [REPLACE] constraints, 1444** do rollbacks or ABORT processing, or [DROP TABLE] processing. The 1445** count does not include rows of views that fire an [INSTEAD OF trigger], 1446** though if the INSTEAD OF trigger makes changes of its own, those changes 1447** are counted.)^ 1448** ^The sqlite3_total_changes() function counts the changes as soon as 1449** the statement that makes them is completed (when the statement handle 1450** is passed to [sqlite3_reset()] or [sqlite3_finalize()]). 1451** 1452** See also the [sqlite3_changes()] interface, the 1453** [count_changes pragma], and the [total_changes() SQL function]. 1454** 1455** If a separate thread makes changes on the same database connection 1456** while [sqlite3_total_changes()] is running then the value 1457** returned is unpredictable and not meaningful. 1458*/ 1459SQLITE_API int sqlite3_total_changes(sqlite3*); 1460 1461/* 1462** CAPI3REF: Interrupt A Long-Running Query 1463** 1464** ^This function causes any pending database operation to abort and 1465** return at its earliest opportunity. This routine is typically 1466** called in response to a user action such as pressing "Cancel" 1467** or Ctrl-C where the user wants a long query operation to halt 1468** immediately. 1469** 1470** ^It is safe to call this routine from a thread different from the 1471** thread that is currently running the database operation. But it 1472** is not safe to call this routine with a [database connection] that 1473** is closed or might close before sqlite3_interrupt() returns. 1474** 1475** ^If an SQL operation is very nearly finished at the time when 1476** sqlite3_interrupt() is called, then it might not have an opportunity 1477** to be interrupted and might continue to completion. 1478** 1479** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT]. 1480** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE 1481** that is inside an explicit transaction, then the entire transaction 1482** will be rolled back automatically. 1483** 1484** ^The sqlite3_interrupt(D) call is in effect until all currently running 1485** SQL statements on [database connection] D complete. ^Any new SQL statements 1486** that are started after the sqlite3_interrupt() call and before the 1487** running statements reaches zero are interrupted as if they had been 1488** running prior to the sqlite3_interrupt() call. ^New SQL statements 1489** that are started after the running statement count reaches zero are 1490** not effected by the sqlite3_interrupt(). 1491** ^A call to sqlite3_interrupt(D) that occurs when there are no running 1492** SQL statements is a no-op and has no effect on SQL statements 1493** that are started after the sqlite3_interrupt() call returns. 1494** 1495** If the database connection closes while [sqlite3_interrupt()] 1496** is running then bad things will likely happen. 1497*/ 1498SQLITE_API void sqlite3_interrupt(sqlite3*); 1499 1500/* 1501** CAPI3REF: Determine If An SQL Statement Is Complete 1502** 1503** These routines are useful during command-line input to determine if the 1504** currently entered text seems to form a complete SQL statement or 1505** if additional input is needed before sending the text into 1506** SQLite for parsing. ^These routines return 1 if the input string 1507** appears to be a complete SQL statement. ^A statement is judged to be 1508** complete if it ends with a semicolon token and is not a prefix of a 1509** well-formed CREATE TRIGGER statement. ^Semicolons that are embedded within 1510** string literals or quoted identifier names or comments are not 1511** independent tokens (they are part of the token in which they are 1512** embedded) and thus do not count as a statement terminator. ^Whitespace 1513** and comments that follow the final semicolon are ignored. 1514** 1515** ^These routines return 0 if the statement is incomplete. ^If a 1516** memory allocation fails, then SQLITE_NOMEM is returned. 1517** 1518** ^These routines do not parse the SQL statements thus 1519** will not detect syntactically incorrect SQL. 1520** 1521** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior 1522** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked 1523** automatically by sqlite3_complete16(). If that initialization fails, 1524** then the return value from sqlite3_complete16() will be non-zero 1525** regardless of whether or not the input SQL is complete.)^ 1526** 1527** The input to [sqlite3_complete()] must be a zero-terminated 1528** UTF-8 string. 1529** 1530** The input to [sqlite3_complete16()] must be a zero-terminated 1531** UTF-16 string in native byte order. 1532*/ 1533SQLITE_API int sqlite3_complete(const char *sql); 1534SQLITE_API int sqlite3_complete16(const void *sql); 1535 1536/* 1537** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors 1538** 1539** ^This routine sets a callback function that might be invoked whenever 1540** an attempt is made to open a database table that another thread 1541** or process has locked. 1542** 1543** ^If the busy callback is NULL, then [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED] 1544** is returned immediately upon encountering the lock. ^If the busy callback 1545** is not NULL, then the callback might be invoked with two arguments. 1546** 1547** ^The first argument to the busy handler is a copy of the void* pointer which 1548** is the third argument to sqlite3_busy_handler(). ^The second argument to 1549** the busy handler callback is the number of times that the busy handler has 1550** been invoked for this locking event. ^If the 1551** busy callback returns 0, then no additional attempts are made to 1552** access the database and [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED] is returned. 1553** ^If the callback returns non-zero, then another attempt 1554** is made to open the database for reading and the cycle repeats. 1555** 1556** The presence of a busy handler does not guarantee that it will be invoked 1557** when there is lock contention. ^If SQLite determines that invoking the busy 1558** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY] 1559** or [SQLITE_IOERR_BLOCKED] instead of invoking the busy handler. 1560** Consider a scenario where one process is holding a read lock that 1561** it is trying to promote to a reserved lock and 1562** a second process is holding a reserved lock that it is trying 1563** to promote to an exclusive lock. The first process cannot proceed 1564** because it is blocked by the second and the second process cannot 1565** proceed because it is blocked by the first. If both processes 1566** invoke the busy handlers, neither will make any progress. Therefore, 1567** SQLite returns [SQLITE_BUSY] for the first process, hoping that this 1568** will induce the first process to release its read lock and allow 1569** the second process to proceed. 1570** 1571** ^The default busy callback is NULL. 1572** 1573** ^The [SQLITE_BUSY] error is converted to [SQLITE_IOERR_BLOCKED] 1574** when SQLite is in the middle of a large transaction where all the 1575** changes will not fit into the in-memory cache. SQLite will 1576** already hold a RESERVED lock on the database file, but it needs 1577** to promote this lock to EXCLUSIVE so that it can spill cache 1578** pages into the database file without harm to concurrent 1579** readers. ^If it is unable to promote the lock, then the in-memory 1580** cache will be left in an inconsistent state and so the error 1581** code is promoted from the relatively benign [SQLITE_BUSY] to 1582** the more severe [SQLITE_IOERR_BLOCKED]. ^This error code promotion 1583** forces an automatic rollback of the changes. See the 1584** <a href="/cvstrac/wiki?p=CorruptionFollowingBusyError"> 1585** CorruptionFollowingBusyError</a> wiki page for a discussion of why 1586** this is important. 1587** 1588** ^(There can only be a single busy handler defined for each 1589** [database connection]. Setting a new busy handler clears any 1590** previously set handler.)^ ^Note that calling [sqlite3_busy_timeout()] 1591** will also set or clear the busy handler. 1592** 1593** The busy callback should not take any actions which modify the 1594** database connection that invoked the busy handler. Any such actions 1595** result in undefined behavior. 1596** 1597** A busy handler must not close the database connection 1598** or [prepared statement] that invoked the busy handler. 1599*/ 1600SQLITE_API int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*); 1601 1602/* 1603** CAPI3REF: Set A Busy Timeout 1604** 1605** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps 1606** for a specified amount of time when a table is locked. ^The handler 1607** will sleep multiple times until at least "ms" milliseconds of sleeping 1608** have accumulated. ^After at least "ms" milliseconds of sleeping, 1609** the handler returns 0 which causes [sqlite3_step()] to return 1610** [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED]. 1611** 1612** ^Calling this routine with an argument less than or equal to zero 1613** turns off all busy handlers. 1614** 1615** ^(There can only be a single busy handler for a particular 1616** [database connection] any any given moment. If another busy handler 1617** was defined (using [sqlite3_busy_handler()]) prior to calling 1618** this routine, that other busy handler is cleared.)^ 1619*/ 1620SQLITE_API int sqlite3_busy_timeout(sqlite3*, int ms); 1621 1622/* 1623** CAPI3REF: Convenience Routines For Running Queries 1624** 1625** Definition: A <b>result table</b> is memory data structure created by the 1626** [sqlite3_get_table()] interface. A result table records the 1627** complete query results from one or more queries. 1628** 1629** The table conceptually has a number of rows and columns. But 1630** these numbers are not part of the result table itself. These 1631** numbers are obtained separately. Let N be the number of rows 1632** and M be the number of columns. 1633** 1634** A result table is an array of pointers to zero-terminated UTF-8 strings. 1635** There are (N+1)*M elements in the array. The first M pointers point 1636** to zero-terminated strings that contain the names of the columns. 1637** The remaining entries all point to query results. NULL values result 1638** in NULL pointers. All other values are in their UTF-8 zero-terminated 1639** string representation as returned by [sqlite3_column_text()]. 1640** 1641** A result table might consist of one or more memory allocations. 1642** It is not safe to pass a result table directly to [sqlite3_free()]. 1643** A result table should be deallocated using [sqlite3_free_table()]. 1644** 1645** As an example of the result table format, suppose a query result 1646** is as follows: 1647** 1648** <blockquote><pre> 1649** Name | Age 1650** ----------------------- 1651** Alice | 43 1652** Bob | 28 1653** Cindy | 21 1654** </pre></blockquote> 1655** 1656** There are two column (M==2) and three rows (N==3). Thus the 1657** result table has 8 entries. Suppose the result table is stored 1658** in an array names azResult. Then azResult holds this content: 1659** 1660** <blockquote><pre> 1661** azResult[0] = "Name"; 1662** azResult[1] = "Age"; 1663** azResult[2] = "Alice"; 1664** azResult[3] = "43"; 1665** azResult[4] = "Bob"; 1666** azResult[5] = "28"; 1667** azResult[6] = "Cindy"; 1668** azResult[7] = "21"; 1669** </pre></blockquote> 1670** 1671** ^The sqlite3_get_table() function evaluates one or more 1672** semicolon-separated SQL statements in the zero-terminated UTF-8 1673** string of its 2nd parameter and returns a result table to the 1674** pointer given in its 3rd parameter. 1675** 1676** After the application has finished with the result from sqlite3_get_table(), 1677** it should pass the result table pointer to sqlite3_free_table() in order to 1678** release the memory that was malloced. Because of the way the 1679** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling 1680** function must not try to call [sqlite3_free()] directly. Only 1681** [sqlite3_free_table()] is able to release the memory properly and safely. 1682** 1683** ^(The sqlite3_get_table() interface is implemented as a wrapper around 1684** [sqlite3_exec()]. The sqlite3_get_table() routine does not have access 1685** to any internal data structures of SQLite. It uses only the public 1686** interface defined here. As a consequence, errors that occur in the 1687** wrapper layer outside of the internal [sqlite3_exec()] call are not 1688** reflected in subsequent calls to [sqlite3_errcode()] or 1689** [sqlite3_errmsg()].)^ 1690*/ 1691SQLITE_API int sqlite3_get_table( 1692 sqlite3 *db, /* An open database */ 1693 const char *zSql, /* SQL to be evaluated */ 1694 char ***pazResult, /* Results of the query */ 1695 int *pnRow, /* Number of result rows written here */ 1696 int *pnColumn, /* Number of result columns written here */ 1697 char **pzErrmsg /* Error msg written here */ 1698); 1699SQLITE_API void sqlite3_free_table(char **result); 1700 1701/* 1702** CAPI3REF: Formatted String Printing Functions 1703** 1704** These routines are work-alikes of the "printf()" family of functions 1705** from the standard C library. 1706** 1707** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their 1708** results into memory obtained from [sqlite3_malloc()]. 1709** The strings returned by these two routines should be 1710** released by [sqlite3_free()]. ^Both routines return a 1711** NULL pointer if [sqlite3_malloc()] is unable to allocate enough 1712** memory to hold the resulting string. 1713** 1714** ^(In sqlite3_snprintf() routine is similar to "snprintf()" from 1715** the standard C library. The result is written into the 1716** buffer supplied as the second parameter whose size is given by 1717** the first parameter. Note that the order of the 1718** first two parameters is reversed from snprintf().)^ This is an 1719** historical accident that cannot be fixed without breaking 1720** backwards compatibility. ^(Note also that sqlite3_snprintf() 1721** returns a pointer to its buffer instead of the number of 1722** characters actually written into the buffer.)^ We admit that 1723** the number of characters written would be a more useful return 1724** value but we cannot change the implementation of sqlite3_snprintf() 1725** now without breaking compatibility. 1726** 1727** ^As long as the buffer size is greater than zero, sqlite3_snprintf() 1728** guarantees that the buffer is always zero-terminated. ^The first 1729** parameter "n" is the total size of the buffer, including space for 1730** the zero terminator. So the longest string that can be completely 1731** written will be n-1 characters. 1732** 1733** These routines all implement some additional formatting 1734** options that are useful for constructing SQL statements. 1735** All of the usual printf() formatting options apply. In addition, there 1736** is are "%q", "%Q", and "%z" options. 1737** 1738** ^(The %q option works like %s in that it substitutes a null-terminated 1739** string from the argument list. But %q also doubles every '\'' character. 1740** %q is designed for use inside a string literal.)^ By doubling each '\'' 1741** character it escapes that character and allows it to be inserted into 1742** the string. 1743** 1744** For example, assume the string variable zText contains text as follows: 1745** 1746** <blockquote><pre> 1747** char *zText = "It's a happy day!"; 1748** </pre></blockquote> 1749** 1750** One can use this text in an SQL statement as follows: 1751** 1752** <blockquote><pre> 1753** char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText); 1754** sqlite3_exec(db, zSQL, 0, 0, 0); 1755** sqlite3_free(zSQL); 1756** </pre></blockquote> 1757** 1758** Because the %q format string is used, the '\'' character in zText 1759** is escaped and the SQL generated is as follows: 1760** 1761** <blockquote><pre> 1762** INSERT INTO table1 VALUES('It''s a happy day!') 1763** </pre></blockquote> 1764** 1765** This is correct. Had we used %s instead of %q, the generated SQL 1766** would have looked like this: 1767** 1768** <blockquote><pre> 1769** INSERT INTO table1 VALUES('It's a happy day!'); 1770** </pre></blockquote> 1771** 1772** This second example is an SQL syntax error. As a general rule you should 1773** always use %q instead of %s when inserting text into a string literal. 1774** 1775** ^(The %Q option works like %q except it also adds single quotes around 1776** the outside of the total string. Additionally, if the parameter in the 1777** argument list is a NULL pointer, %Q substitutes the text "NULL" (without 1778** single quotes).)^ So, for example, one could say: 1779** 1780** <blockquote><pre> 1781** char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText); 1782** sqlite3_exec(db, zSQL, 0, 0, 0); 1783** sqlite3_free(zSQL); 1784** </pre></blockquote> 1785** 1786** The code above will render a correct SQL statement in the zSQL 1787** variable even if the zText variable is a NULL pointer. 1788** 1789** ^(The "%z" formatting option works like "%s" but with the 1790** addition that after the string has been read and copied into 1791** the result, [sqlite3_free()] is called on the input string.)^ 1792*/ 1793SQLITE_API char *sqlite3_mprintf(const char*,...); 1794SQLITE_API char *sqlite3_vmprintf(const char*, va_list); 1795SQLITE_API char *sqlite3_snprintf(int,char*,const char*, ...); 1796 1797/* 1798** CAPI3REF: Memory Allocation Subsystem 1799** 1800** The SQLite core uses these three routines for all of its own 1801** internal memory allocation needs. "Core" in the previous sentence 1802** does not include operating-system specific VFS implementation. The 1803** Windows VFS uses native malloc() and free() for some operations. 1804** 1805** ^The sqlite3_malloc() routine returns a pointer to a block 1806** of memory at least N bytes in length, where N is the parameter. 1807** ^If sqlite3_malloc() is unable to obtain sufficient free 1808** memory, it returns a NULL pointer. ^If the parameter N to 1809** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns 1810** a NULL pointer. 1811** 1812** ^Calling sqlite3_free() with a pointer previously returned 1813** by sqlite3_malloc() or sqlite3_realloc() releases that memory so 1814** that it might be reused. ^The sqlite3_free() routine is 1815** a no-op if is called with a NULL pointer. Passing a NULL pointer 1816** to sqlite3_free() is harmless. After being freed, memory 1817** should neither be read nor written. Even reading previously freed 1818** memory might result in a segmentation fault or other severe error. 1819** Memory corruption, a segmentation fault, or other severe error 1820** might result if sqlite3_free() is called with a non-NULL pointer that 1821** was not obtained from sqlite3_malloc() or sqlite3_realloc(). 1822** 1823** ^(The sqlite3_realloc() interface attempts to resize a 1824** prior memory allocation to be at least N bytes, where N is the 1825** second parameter. The memory allocation to be resized is the first 1826** parameter.)^ ^ If the first parameter to sqlite3_realloc() 1827** is a NULL pointer then its behavior is identical to calling 1828** sqlite3_malloc(N) where N is the second parameter to sqlite3_realloc(). 1829** ^If the second parameter to sqlite3_realloc() is zero or 1830** negative then the behavior is exactly the same as calling 1831** sqlite3_free(P) where P is the first parameter to sqlite3_realloc(). 1832** ^sqlite3_realloc() returns a pointer to a memory allocation 1833** of at least N bytes in size or NULL if sufficient memory is unavailable. 1834** ^If M is the size of the prior allocation, then min(N,M) bytes 1835** of the prior allocation are copied into the beginning of buffer returned 1836** by sqlite3_realloc() and the prior allocation is freed. 1837** ^If sqlite3_realloc() returns NULL, then the prior allocation 1838** is not freed. 1839** 1840** ^The memory returned by sqlite3_malloc() and sqlite3_realloc() 1841** is always aligned to at least an 8 byte boundary. 1842** 1843** In SQLite version 3.5.0 and 3.5.1, it was possible to define 1844** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in 1845** implementation of these routines to be omitted. That capability 1846** is no longer provided. Only built-in memory allocators can be used. 1847** 1848** The Windows OS interface layer calls 1849** the system malloc() and free() directly when converting 1850** filenames between the UTF-8 encoding used by SQLite 1851** and whatever filename encoding is used by the particular Windows 1852** installation. Memory allocation errors are detected, but 1853** they are reported back as [SQLITE_CANTOPEN] or 1854** [SQLITE_IOERR] rather than [SQLITE_NOMEM]. 1855** 1856** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()] 1857** must be either NULL or else pointers obtained from a prior 1858** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have 1859** not yet been released. 1860** 1861** The application must not read or write any part of 1862** a block of memory after it has been released using 1863** [sqlite3_free()] or [sqlite3_realloc()]. 1864*/ 1865SQLITE_API void *sqlite3_malloc(int); 1866SQLITE_API void *sqlite3_realloc(void*, int); 1867SQLITE_API void sqlite3_free(void*); 1868 1869/* 1870** CAPI3REF: Memory Allocator Statistics 1871** 1872** SQLite provides these two interfaces for reporting on the status 1873** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()] 1874** routines, which form the built-in memory allocation subsystem. 1875** 1876** ^The [sqlite3_memory_used()] routine returns the number of bytes 1877** of memory currently outstanding (malloced but not freed). 1878** ^The [sqlite3_memory_highwater()] routine returns the maximum 1879** value of [sqlite3_memory_used()] since the high-water mark 1880** was last reset. ^The values returned by [sqlite3_memory_used()] and 1881** [sqlite3_memory_highwater()] include any overhead 1882** added by SQLite in its implementation of [sqlite3_malloc()], 1883** but not overhead added by the any underlying system library 1884** routines that [sqlite3_malloc()] may call. 1885** 1886** ^The memory high-water mark is reset to the current value of 1887** [sqlite3_memory_used()] if and only if the parameter to 1888** [sqlite3_memory_highwater()] is true. ^The value returned 1889** by [sqlite3_memory_highwater(1)] is the high-water mark 1890** prior to the reset. 1891*/ 1892SQLITE_API sqlite3_int64 sqlite3_memory_used(void); 1893SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag); 1894 1895/* 1896** CAPI3REF: Pseudo-Random Number Generator 1897** 1898** SQLite contains a high-quality pseudo-random number generator (PRNG) used to 1899** select random [ROWID | ROWIDs] when inserting new records into a table that 1900** already uses the largest possible [ROWID]. The PRNG is also used for 1901** the build-in random() and randomblob() SQL functions. This interface allows 1902** applications to access the same PRNG for other purposes. 1903** 1904** ^A call to this routine stores N bytes of randomness into buffer P. 1905** 1906** ^The first time this routine is invoked (either internally or by 1907** the application) the PRNG is seeded using randomness obtained 1908** from the xRandomness method of the default [sqlite3_vfs] object. 1909** ^On all subsequent invocations, the pseudo-randomness is generated 1910** internally and without recourse to the [sqlite3_vfs] xRandomness 1911** method. 1912*/ 1913SQLITE_API void sqlite3_randomness(int N, void *P); 1914 1915/* 1916** CAPI3REF: Compile-Time Authorization Callbacks 1917** 1918** ^This routine registers a authorizer callback with a particular 1919** [database connection], supplied in the first argument. 1920** ^The authorizer callback is invoked as SQL statements are being compiled 1921** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()], 1922** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()]. ^At various 1923** points during the compilation process, as logic is being created 1924** to perform various actions, the authorizer callback is invoked to 1925** see if those actions are allowed. ^The authorizer callback should 1926** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the 1927** specific action but allow the SQL statement to continue to be 1928** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be 1929** rejected with an error. ^If the authorizer callback returns 1930** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY] 1931** then the [sqlite3_prepare_v2()] or equivalent call that triggered 1932** the authorizer will fail with an error message. 1933** 1934** When the callback returns [SQLITE_OK], that means the operation 1935** requested is ok. ^When the callback returns [SQLITE_DENY], the 1936** [sqlite3_prepare_v2()] or equivalent call that triggered the 1937** authorizer will fail with an error message explaining that 1938** access is denied. 1939** 1940** ^The first parameter to the authorizer callback is a copy of the third 1941** parameter to the sqlite3_set_authorizer() interface. ^The second parameter 1942** to the callback is an integer [SQLITE_COPY | action code] that specifies 1943** the particular action to be authorized. ^The third through sixth parameters 1944** to the callback are zero-terminated strings that contain additional 1945** details about the action to be authorized. 1946** 1947** ^If the action code is [SQLITE_READ] 1948** and the callback returns [SQLITE_IGNORE] then the 1949** [prepared statement] statement is constructed to substitute 1950** a NULL value in place of the table column that would have 1951** been read if [SQLITE_OK] had been returned. The [SQLITE_IGNORE] 1952** return can be used to deny an untrusted user access to individual 1953** columns of a table. 1954** ^If the action code is [SQLITE_DELETE] and the callback returns 1955** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the 1956** [truncate optimization] is disabled and all rows are deleted individually. 1957** 1958** An authorizer is used when [sqlite3_prepare | preparing] 1959** SQL statements from an untrusted source, to ensure that the SQL statements 1960** do not try to access data they are not allowed to see, or that they do not 1961** try to execute malicious statements that damage the database. For 1962** example, an application may allow a user to enter arbitrary 1963** SQL queries for evaluation by a database. But the application does 1964** not want the user to be able to make arbitrary changes to the 1965** database. An authorizer could then be put in place while the 1966** user-entered SQL is being [sqlite3_prepare | prepared] that 1967** disallows everything except [SELECT] statements. 1968** 1969** Applications that need to process SQL from untrusted sources 1970** might also consider lowering resource limits using [sqlite3_limit()] 1971** and limiting database size using the [max_page_count] [PRAGMA] 1972** in addition to using an authorizer. 1973** 1974** ^(Only a single authorizer can be in place on a database connection 1975** at a time. Each call to sqlite3_set_authorizer overrides the 1976** previous call.)^ ^Disable the authorizer by installing a NULL callback. 1977** The authorizer is disabled by default. 1978** 1979** The authorizer callback must not do anything that will modify 1980** the database connection that invoked the authorizer callback. 1981** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their 1982** database connections for the meaning of "modify" in this paragraph. 1983** 1984** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the 1985** statement might be re-prepared during [sqlite3_step()] due to a 1986** schema change. Hence, the application should ensure that the 1987** correct authorizer callback remains in place during the [sqlite3_step()]. 1988** 1989** ^Note that the authorizer callback is invoked only during 1990** [sqlite3_prepare()] or its variants. Authorization is not 1991** performed during statement evaluation in [sqlite3_step()], unless 1992** as stated in the previous paragraph, sqlite3_step() invokes 1993** sqlite3_prepare_v2() to reprepare a statement after a schema change. 1994*/ 1995SQLITE_API int sqlite3_set_authorizer( 1996 sqlite3*, 1997 int (*xAuth)(void*,int,const char*,const char*,const char*,const char*), 1998 void *pUserData 1999); 2000 2001/* 2002** CAPI3REF: Authorizer Return Codes 2003** 2004** The [sqlite3_set_authorizer | authorizer callback function] must 2005** return either [SQLITE_OK] or one of these two constants in order 2006** to signal SQLite whether or not the action is permitted. See the 2007** [sqlite3_set_authorizer | authorizer documentation] for additional 2008** information. 2009*/ 2010#define SQLITE_DENY 1 /* Abort the SQL statement with an error */ 2011#define SQLITE_IGNORE 2 /* Don't allow access, but don't generate an error */ 2012 2013/* 2014** CAPI3REF: Authorizer Action Codes 2015** 2016** The [sqlite3_set_authorizer()] interface registers a callback function 2017** that is invoked to authorize certain SQL statement actions. The 2018** second parameter to the callback is an integer code that specifies 2019** what action is being authorized. These are the integer action codes that 2020** the authorizer callback may be passed. 2021** 2022** These action code values signify what kind of operation is to be 2023** authorized. The 3rd and 4th parameters to the authorization 2024** callback function will be parameters or NULL depending on which of these 2025** codes is used as the second parameter. ^(The 5th parameter to the 2026** authorizer callback is the name of the database ("main", "temp", 2027** etc.) if applicable.)^ ^The 6th parameter to the authorizer callback 2028** is the name of the inner-most trigger or view that is responsible for 2029** the access attempt or NULL if this access attempt is directly from 2030** top-level SQL code. 2031*/ 2032/******************************************* 3rd ************ 4th ***********/ 2033#define SQLITE_CREATE_INDEX 1 /* Index Name Table Name */ 2034#define SQLITE_CREATE_TABLE 2 /* Table Name NULL */ 2035#define SQLITE_CREATE_TEMP_INDEX 3 /* Index Name Table Name */ 2036#define SQLITE_CREATE_TEMP_TABLE 4 /* Table Name NULL */ 2037#define SQLITE_CREATE_TEMP_TRIGGER 5 /* Trigger Name Table Name */ 2038#define SQLITE_CREATE_TEMP_VIEW 6 /* View Name NULL */ 2039#define SQLITE_CREATE_TRIGGER 7 /* Trigger Name Table Name */ 2040#define SQLITE_CREATE_VIEW 8 /* View Name NULL */ 2041#define SQLITE_DELETE 9 /* Table Name NULL */ 2042#define SQLITE_DROP_INDEX 10 /* Index Name Table Name */ 2043#define SQLITE_DROP_TABLE 11 /* Table Name NULL */ 2044#define SQLITE_DROP_TEMP_INDEX 12 /* Index Name Table Name */ 2045#define SQLITE_DROP_TEMP_TABLE 13 /* Table Name NULL */ 2046#define SQLITE_DROP_TEMP_TRIGGER 14 /* Trigger Name Table Name */ 2047#define SQLITE_DROP_TEMP_VIEW 15 /* View Name NULL */ 2048#define SQLITE_DROP_TRIGGER 16 /* Trigger Name Table Name */ 2049#define SQLITE_DROP_VIEW 17 /* View Name NULL */ 2050#define SQLITE_INSERT 18 /* Table Name NULL */ 2051#define SQLITE_PRAGMA 19 /* Pragma Name 1st arg or NULL */ 2052#define SQLITE_READ 20 /* Table Name Column Name */ 2053#define SQLITE_SELECT 21 /* NULL NULL */ 2054#define SQLITE_TRANSACTION 22 /* Operation NULL */ 2055#define SQLITE_UPDATE 23 /* Table Name Column Name */ 2056#define SQLITE_ATTACH 24 /* Filename NULL */ 2057#define SQLITE_DETACH 25 /* Database Name NULL */ 2058#define SQLITE_ALTER_TABLE 26 /* Database Name Table Name */ 2059#define SQLITE_REINDEX 27 /* Index Name NULL */ 2060#define SQLITE_ANALYZE 28 /* Table Name NULL */ 2061#define SQLITE_CREATE_VTABLE 29 /* Table Name Module Name */ 2062#define SQLITE_DROP_VTABLE 30 /* Table Name Module Name */ 2063#define SQLITE_FUNCTION 31 /* NULL Function Name */ 2064#define SQLITE_SAVEPOINT 32 /* Operation Savepoint Name */ 2065#define SQLITE_COPY 0 /* No longer used */ 2066 2067/* 2068** CAPI3REF: Tracing And Profiling Functions 2069** EXPERIMENTAL 2070** 2071** These routines register callback functions that can be used for 2072** tracing and profiling the execution of SQL statements. 2073** 2074** ^The callback function registered by sqlite3_trace() is invoked at 2075** various times when an SQL statement is being run by [sqlite3_step()]. 2076** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the 2077** SQL statement text as the statement first begins executing. 2078** ^(Additional sqlite3_trace() callbacks might occur 2079** as each triggered subprogram is entered. The callbacks for triggers 2080** contain a UTF-8 SQL comment that identifies the trigger.)^ 2081** 2082** ^The callback function registered by sqlite3_profile() is invoked 2083** as each SQL statement finishes. ^The profile callback contains 2084** the original statement text and an estimate of wall-clock time 2085** of how long that statement took to run. 2086*/ 2087SQLITE_API SQLITE_EXPERIMENTAL void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*); 2088SQLITE_API SQLITE_EXPERIMENTAL void *sqlite3_profile(sqlite3*, 2089 void(*xProfile)(void*,const char*,sqlite3_uint64), void*); 2090 2091/* 2092** CAPI3REF: Query Progress Callbacks 2093** 2094** ^This routine configures a callback function - the 2095** progress callback - that is invoked periodically during long 2096** running calls to [sqlite3_exec()], [sqlite3_step()] and 2097** [sqlite3_get_table()]. An example use for this 2098** interface is to keep a GUI updated during a large query. 2099** 2100** ^If the progress callback returns non-zero, the operation is 2101** interrupted. This feature can be used to implement a 2102** "Cancel" button on a GUI progress dialog box. 2103** 2104** The progress handler must not do anything that will modify 2105** the database connection that invoked the progress handler. 2106** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their 2107** database connections for the meaning of "modify" in this paragraph. 2108** 2109*/ 2110SQLITE_API void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*); 2111 2112/* 2113** CAPI3REF: Opening A New Database Connection 2114** 2115** ^These routines open an SQLite database file whose name is given by the 2116** filename argument. ^The filename argument is interpreted as UTF-8 for 2117** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte 2118** order for sqlite3_open16(). ^(A [database connection] handle is usually 2119** returned in *ppDb, even if an error occurs. The only exception is that 2120** if SQLite is unable to allocate memory to hold the [sqlite3] object, 2121** a NULL will be written into *ppDb instead of a pointer to the [sqlite3] 2122** object.)^ ^(If the database is opened (and/or created) successfully, then 2123** [SQLITE_OK] is returned. Otherwise an [error code] is returned.)^ ^The 2124** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain 2125** an English language description of the error following a failure of any 2126** of the sqlite3_open() routines. 2127** 2128** ^The default encoding for the database will be UTF-8 if 2129** sqlite3_open() or sqlite3_open_v2() is called and 2130** UTF-16 in the native byte order if sqlite3_open16() is used. 2131** 2132** Whether or not an error occurs when it is opened, resources 2133** associated with the [database connection] handle should be released by 2134** passing it to [sqlite3_close()] when it is no longer required. 2135** 2136** The sqlite3_open_v2() interface works like sqlite3_open() 2137** except that it accepts two additional parameters for additional control 2138** over the new database connection. ^(The flags parameter to 2139** sqlite3_open_v2() can take one of 2140** the following three values, optionally combined with the 2141** [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE], 2142** and/or [SQLITE_OPEN_PRIVATECACHE] flags:)^ 2143** 2144** <dl> 2145** ^(<dt>[SQLITE_OPEN_READONLY]</dt> 2146** <dd>The database is opened in read-only mode. If the database does not 2147** already exist, an error is returned.</dd>)^ 2148** 2149** ^(<dt>[SQLITE_OPEN_READWRITE]</dt> 2150** <dd>The database is opened for reading and writing if possible, or reading 2151** only if the file is write protected by the operating system. In either 2152** case the database must already exist, otherwise an error is returned.</dd>)^ 2153** 2154** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt> 2155** <dd>The database is opened for reading and writing, and is creates it if 2156** it does not already exist. This is the behavior that is always used for 2157** sqlite3_open() and sqlite3_open16().</dd>)^ 2158** </dl> 2159** 2160** If the 3rd parameter to sqlite3_open_v2() is not one of the 2161** combinations shown above or one of the combinations shown above combined 2162** with the [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], 2163** [SQLITE_OPEN_SHAREDCACHE] and/or [SQLITE_OPEN_SHAREDCACHE] flags, 2164** then the behavior is undefined. 2165** 2166** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection 2167** opens in the multi-thread [threading mode] as long as the single-thread 2168** mode has not been set at compile-time or start-time. ^If the 2169** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens 2170** in the serialized [threading mode] unless single-thread was 2171** previously selected at compile-time or start-time. 2172** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be 2173** eligible to use [shared cache mode], regardless of whether or not shared 2174** cache is enabled using [sqlite3_enable_shared_cache()]. ^The 2175** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not 2176** participate in [shared cache mode] even if it is enabled. 2177** 2178** ^If the filename is ":memory:", then a private, temporary in-memory database 2179** is created for the connection. ^This in-memory database will vanish when 2180** the database connection is closed. Future versions of SQLite might 2181** make use of additional special filenames that begin with the ":" character. 2182** It is recommended that when a database filename actually does begin with 2183** a ":" character you should prefix the filename with a pathname such as 2184** "./" to avoid ambiguity. 2185** 2186** ^If the filename is an empty string, then a private, temporary 2187** on-disk database will be created. ^This private database will be 2188** automatically deleted as soon as the database connection is closed. 2189** 2190** ^The fourth parameter to sqlite3_open_v2() is the name of the 2191** [sqlite3_vfs] object that defines the operating system interface that 2192** the new database connection should use. ^If the fourth parameter is 2193** a NULL pointer then the default [sqlite3_vfs] object is used. 2194** 2195** <b>Note to Windows users:</b> The encoding used for the filename argument 2196** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever 2197** codepage is currently defined. Filenames containing international 2198** characters must be converted to UTF-8 prior to passing them into 2199** sqlite3_open() or sqlite3_open_v2(). 2200*/ 2201SQLITE_API int sqlite3_open( 2202 const char *filename, /* Database filename (UTF-8) */ 2203 sqlite3 **ppDb /* OUT: SQLite db handle */ 2204); 2205SQLITE_API int sqlite3_open16( 2206 const void *filename, /* Database filename (UTF-16) */ 2207 sqlite3 **ppDb /* OUT: SQLite db handle */ 2208); 2209SQLITE_API int sqlite3_open_v2( 2210 const char *filename, /* Database filename (UTF-8) */ 2211 sqlite3 **ppDb, /* OUT: SQLite db handle */ 2212 int flags, /* Flags */ 2213 const char *zVfs /* Name of VFS module to use */ 2214); 2215 2216/* 2217** CAPI3REF: Error Codes And Messages 2218** 2219** ^The sqlite3_errcode() interface returns the numeric [result code] or 2220** [extended result code] for the most recent failed sqlite3_* API call 2221** associated with a [database connection]. If a prior API call failed 2222** but the most recent API call succeeded, the return value from 2223** sqlite3_errcode() is undefined. ^The sqlite3_extended_errcode() 2224** interface is the same except that it always returns the 2225** [extended result code] even when extended result codes are 2226** disabled. 2227** 2228** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language 2229** text that describes the error, as either UTF-8 or UTF-16 respectively. 2230** ^(Memory to hold the error message string is managed internally. 2231** The application does not need to worry about freeing the result. 2232** However, the error string might be overwritten or deallocated by 2233** subsequent calls to other SQLite interface functions.)^ 2234** 2235** When the serialized [threading mode] is in use, it might be the 2236** case that a second error occurs on a separate thread in between 2237** the time of the first error and the call to these interfaces. 2238** When that happens, the second error will be reported since these 2239** interfaces always report the most recent result. To avoid 2240** this, each thread can obtain exclusive use of the [database connection] D 2241** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning 2242** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after 2243** all calls to the interfaces listed here are completed. 2244** 2245** If an interface fails with SQLITE_MISUSE, that means the interface 2246** was invoked incorrectly by the application. In that case, the 2247** error code and message may or may not be set. 2248*/ 2249SQLITE_API int sqlite3_errcode(sqlite3 *db); 2250SQLITE_API int sqlite3_extended_errcode(sqlite3 *db); 2251SQLITE_API const char *sqlite3_errmsg(sqlite3*); 2252SQLITE_API const void *sqlite3_errmsg16(sqlite3*); 2253 2254/* 2255** CAPI3REF: SQL Statement Object 2256** KEYWORDS: {prepared statement} {prepared statements} 2257** 2258** An instance of this object represents a single SQL statement. 2259** This object is variously known as a "prepared statement" or a 2260** "compiled SQL statement" or simply as a "statement". 2261** 2262** The life of a statement object goes something like this: 2263** 2264** <ol> 2265** <li> Create the object using [sqlite3_prepare_v2()] or a related 2266** function. 2267** <li> Bind values to [host parameters] using the sqlite3_bind_*() 2268** interfaces. 2269** <li> Run the SQL by calling [sqlite3_step()] one or more times. 2270** <li> Reset the statement using [sqlite3_reset()] then go back 2271** to step 2. Do this zero or more times. 2272** <li> Destroy the object using [sqlite3_finalize()]. 2273** </ol> 2274** 2275** Refer to documentation on individual methods above for additional 2276** information. 2277*/ 2278typedef struct sqlite3_stmt sqlite3_stmt; 2279 2280/* 2281** CAPI3REF: Run-time Limits 2282** 2283** ^(This interface allows the size of various constructs to be limited 2284** on a connection by connection basis. The first parameter is the 2285** [database connection] whose limit is to be set or queried. The 2286** second parameter is one of the [limit categories] that define a 2287** class of constructs to be size limited. The third parameter is the 2288** new limit for that construct. The function returns the old limit.)^ 2289** 2290** ^If the new limit is a negative number, the limit is unchanged. 2291** ^(For the limit category of SQLITE_LIMIT_XYZ there is a 2292** [limits | hard upper bound] 2293** set by a compile-time C preprocessor macro named 2294** [limits | SQLITE_MAX_XYZ]. 2295** (The "_LIMIT_" in the name is changed to "_MAX_".))^ 2296** ^Attempts to increase a limit above its hard upper bound are 2297** silently truncated to the hard upper bound. 2298** 2299** Run-time limits are intended for use in applications that manage 2300** both their own internal database and also databases that are controlled 2301** by untrusted external sources. An example application might be a 2302** web browser that has its own databases for storing history and 2303** separate databases controlled by JavaScript applications downloaded 2304** off the Internet. The internal databases can be given the 2305** large, default limits. Databases managed by external sources can 2306** be given much smaller limits designed to prevent a denial of service 2307** attack. Developers might also want to use the [sqlite3_set_authorizer()] 2308** interface to further control untrusted SQL. The size of the database 2309** created by an untrusted script can be contained using the 2310** [max_page_count] [PRAGMA]. 2311** 2312** New run-time limit categories may be added in future releases. 2313*/ 2314SQLITE_API int sqlite3_limit(sqlite3*, int id, int newVal); 2315 2316/* 2317** CAPI3REF: Run-Time Limit Categories 2318** KEYWORDS: {limit category} {*limit categories} 2319** 2320** These constants define various performance limits 2321** that can be lowered at run-time using [sqlite3_limit()]. 2322** The synopsis of the meanings of the various limits is shown below. 2323** Additional information is available at [limits | Limits in SQLite]. 2324** 2325** <dl> 2326** ^(<dt>SQLITE_LIMIT_LENGTH</dt> 2327** <dd>The maximum size of any string or BLOB or table row.<dd>)^ 2328** 2329** ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt> 2330** <dd>The maximum length of an SQL statement, in bytes.</dd>)^ 2331** 2332** ^(<dt>SQLITE_LIMIT_COLUMN</dt> 2333** <dd>The maximum number of columns in a table definition or in the 2334** result set of a [SELECT] or the maximum number of columns in an index 2335** or in an ORDER BY or GROUP BY clause.</dd>)^ 2336** 2337** ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt> 2338** <dd>The maximum depth of the parse tree on any expression.</dd>)^ 2339** 2340** ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt> 2341** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^ 2342** 2343** ^(<dt>SQLITE_LIMIT_VDBE_OP</dt> 2344** <dd>The maximum number of instructions in a virtual machine program 2345** used to implement an SQL statement.</dd>)^ 2346** 2347** ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt> 2348** <dd>The maximum number of arguments on a function.</dd>)^ 2349** 2350** ^(<dt>SQLITE_LIMIT_ATTACHED</dt> 2351** <dd>The maximum number of [ATTACH | attached databases].)^</dd> 2352** 2353** ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt> 2354** <dd>The maximum length of the pattern argument to the [LIKE] or 2355** [GLOB] operators.</dd>)^ 2356** 2357** ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt> 2358** <dd>The maximum number of variables in an SQL statement that can 2359** be bound.</dd>)^ 2360** 2361** ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt> 2362** <dd>The maximum depth of recursion for triggers.</dd>)^ 2363** </dl> 2364*/ 2365#define SQLITE_LIMIT_LENGTH 0 2366#define SQLITE_LIMIT_SQL_LENGTH 1 2367#define SQLITE_LIMIT_COLUMN 2 2368#define SQLITE_LIMIT_EXPR_DEPTH 3 2369#define SQLITE_LIMIT_COMPOUND_SELECT 4 2370#define SQLITE_LIMIT_VDBE_OP 5 2371#define SQLITE_LIMIT_FUNCTION_ARG 6 2372#define SQLITE_LIMIT_ATTACHED 7 2373#define SQLITE_LIMIT_LIKE_PATTERN_LENGTH 8 2374#define SQLITE_LIMIT_VARIABLE_NUMBER 9 2375#define SQLITE_LIMIT_TRIGGER_DEPTH 10 2376 2377/* 2378** CAPI3REF: Compiling An SQL Statement 2379** KEYWORDS: {SQL statement compiler} 2380** 2381** To execute an SQL query, it must first be compiled into a byte-code 2382** program using one of these routines. 2383** 2384** The first argument, "db", is a [database connection] obtained from a 2385** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or 2386** [sqlite3_open16()]. The database connection must not have been closed. 2387** 2388** The second argument, "zSql", is the statement to be compiled, encoded 2389** as either UTF-8 or UTF-16. The sqlite3_prepare() and sqlite3_prepare_v2() 2390** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2() 2391** use UTF-16. 2392** 2393** ^If the nByte argument is less than zero, then zSql is read up to the 2394** first zero terminator. ^If nByte is non-negative, then it is the maximum 2395** number of bytes read from zSql. ^When nByte is non-negative, the 2396** zSql string ends at either the first '\000' or '\u0000' character or 2397** the nByte-th byte, whichever comes first. If the caller knows 2398** that the supplied string is nul-terminated, then there is a small 2399** performance advantage to be gained by passing an nByte parameter that 2400** is equal to the number of bytes in the input string <i>including</i> 2401** the nul-terminator bytes. 2402** 2403** ^If pzTail is not NULL then *pzTail is made to point to the first byte 2404** past the end of the first SQL statement in zSql. These routines only 2405** compile the first statement in zSql, so *pzTail is left pointing to 2406** what remains uncompiled. 2407** 2408** ^*ppStmt is left pointing to a compiled [prepared statement] that can be 2409** executed using [sqlite3_step()]. ^If there is an error, *ppStmt is set 2410** to NULL. ^If the input text contains no SQL (if the input is an empty 2411** string or a comment) then *ppStmt is set to NULL. 2412** The calling procedure is responsible for deleting the compiled 2413** SQL statement using [sqlite3_finalize()] after it has finished with it. 2414** ppStmt may not be NULL. 2415** 2416** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK]; 2417** otherwise an [error code] is returned. 2418** 2419** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are 2420** recommended for all new programs. The two older interfaces are retained 2421** for backwards compatibility, but their use is discouraged. 2422** ^In the "v2" interfaces, the prepared statement 2423** that is returned (the [sqlite3_stmt] object) contains a copy of the 2424** original SQL text. This causes the [sqlite3_step()] interface to 2425** behave differently in three ways: 2426** 2427** <ol> 2428** <li> 2429** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it 2430** always used to do, [sqlite3_step()] will automatically recompile the SQL 2431** statement and try to run it again. ^If the schema has changed in 2432** a way that makes the statement no longer valid, [sqlite3_step()] will still 2433** return [SQLITE_SCHEMA]. But unlike the legacy behavior, [SQLITE_SCHEMA] is 2434** now a fatal error. Calling [sqlite3_prepare_v2()] again will not make the 2435** error go away. Note: use [sqlite3_errmsg()] to find the text 2436** of the parsing error that results in an [SQLITE_SCHEMA] return. 2437** </li> 2438** 2439** <li> 2440** ^When an error occurs, [sqlite3_step()] will return one of the detailed 2441** [error codes] or [extended error codes]. ^The legacy behavior was that 2442** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code 2443** and the application would have to make a second call to [sqlite3_reset()] 2444** in order to find the underlying cause of the problem. With the "v2" prepare 2445** interfaces, the underlying reason for the error is returned immediately. 2446** </li> 2447** 2448** <li> 2449** ^If the value of a [parameter | host parameter] in the WHERE clause might 2450** change the query plan for a statement, then the statement may be 2451** automatically recompiled (as if there had been a schema change) on the first 2452** [sqlite3_step()] call following any change to the 2453** [sqlite3_bind_text | bindings] of the [parameter]. 2454** </li> 2455** </ol> 2456*/ 2457SQLITE_API int sqlite3_prepare( 2458 sqlite3 *db, /* Database handle */ 2459 const char *zSql, /* SQL statement, UTF-8 encoded */ 2460 int nByte, /* Maximum length of zSql in bytes. */ 2461 sqlite3_stmt **ppStmt, /* OUT: Statement handle */ 2462 const char **pzTail /* OUT: Pointer to unused portion of zSql */ 2463); 2464SQLITE_API int sqlite3_prepare_v2( 2465 sqlite3 *db, /* Database handle */ 2466 const char *zSql, /* SQL statement, UTF-8 encoded */ 2467 int nByte, /* Maximum length of zSql in bytes. */ 2468 sqlite3_stmt **ppStmt, /* OUT: Statement handle */ 2469 const char **pzTail /* OUT: Pointer to unused portion of zSql */ 2470); 2471SQLITE_API int sqlite3_prepare16( 2472 sqlite3 *db, /* Database handle */ 2473 const void *zSql, /* SQL statement, UTF-16 encoded */ 2474 int nByte, /* Maximum length of zSql in bytes. */ 2475 sqlite3_stmt **ppStmt, /* OUT: Statement handle */ 2476 const void **pzTail /* OUT: Pointer to unused portion of zSql */ 2477); 2478SQLITE_API int sqlite3_prepare16_v2( 2479 sqlite3 *db, /* Database handle */ 2480 const void *zSql, /* SQL statement, UTF-16 encoded */ 2481 int nByte, /* Maximum length of zSql in bytes. */ 2482 sqlite3_stmt **ppStmt, /* OUT: Statement handle */ 2483 const void **pzTail /* OUT: Pointer to unused portion of zSql */ 2484); 2485 2486/* 2487** CAPI3REF: Retrieving Statement SQL 2488** 2489** ^This interface can be used to retrieve a saved copy of the original 2490** SQL text used to create a [prepared statement] if that statement was 2491** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()]. 2492*/ 2493SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt); 2494 2495/* 2496** CAPI3REF: Dynamically Typed Value Object 2497** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value} 2498** 2499** SQLite uses the sqlite3_value object to represent all values 2500** that can be stored in a database table. SQLite uses dynamic typing 2501** for the values it stores. ^Values stored in sqlite3_value objects 2502** can be integers, floating point values, strings, BLOBs, or NULL. 2503** 2504** An sqlite3_value object may be either "protected" or "unprotected". 2505** Some interfaces require a protected sqlite3_value. Other interfaces 2506** will accept either a protected or an unprotected sqlite3_value. 2507** Every interface that accepts sqlite3_value arguments specifies 2508** whether or not it requires a protected sqlite3_value. 2509** 2510** The terms "protected" and "unprotected" refer to whether or not 2511** a mutex is held. A internal mutex is held for a protected 2512** sqlite3_value object but no mutex is held for an unprotected 2513** sqlite3_value object. If SQLite is compiled to be single-threaded 2514** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0) 2515** or if SQLite is run in one of reduced mutex modes 2516** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD] 2517** then there is no distinction between protected and unprotected 2518** sqlite3_value objects and they can be used interchangeably. However, 2519** for maximum code portability it is recommended that applications 2520** still make the distinction between between protected and unprotected 2521** sqlite3_value objects even when not strictly required. 2522** 2523** ^The sqlite3_value objects that are passed as parameters into the 2524** implementation of [application-defined SQL functions] are protected. 2525** ^The sqlite3_value object returned by 2526** [sqlite3_column_value()] is unprotected. 2527** Unprotected sqlite3_value objects may only be used with 2528** [sqlite3_result_value()] and [sqlite3_bind_value()]. 2529** The [sqlite3_value_blob | sqlite3_value_type()] family of 2530** interfaces require protected sqlite3_value objects. 2531*/ 2532typedef struct Mem sqlite3_value; 2533 2534/* 2535** CAPI3REF: SQL Function Context Object 2536** 2537** The context in which an SQL function executes is stored in an 2538** sqlite3_context object. ^A pointer to an sqlite3_context object 2539** is always first parameter to [application-defined SQL functions]. 2540** The application-defined SQL function implementation will pass this 2541** pointer through into calls to [sqlite3_result_int | sqlite3_result()], 2542** [sqlite3_aggregate_context()], [sqlite3_user_data()], 2543** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()], 2544** and/or [sqlite3_set_auxdata()]. 2545*/ 2546typedef struct sqlite3_context sqlite3_context; 2547 2548/* 2549** CAPI3REF: Binding Values To Prepared Statements 2550** KEYWORDS: {host parameter} {host parameters} {host parameter name} 2551** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding} 2552** 2553** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants, 2554** literals may be replaced by a [parameter] that matches one of following 2555** templates: 2556** 2557** <ul> 2558** <li> ? 2559** <li> ?NNN 2560** <li> :VVV 2561** <li> @VVV 2562** <li> $VVV 2563** </ul> 2564** 2565** In the templates above, NNN represents an integer literal, 2566** and VVV represents an alphanumeric identifer.)^ ^The values of these 2567** parameters (also called "host parameter names" or "SQL parameters") 2568** can be set using the sqlite3_bind_*() routines defined here. 2569** 2570** ^The first argument to the sqlite3_bind_*() routines is always 2571** a pointer to the [sqlite3_stmt] object returned from 2572** [sqlite3_prepare_v2()] or its variants. 2573** 2574** ^The second argument is the index of the SQL parameter to be set. 2575** ^The leftmost SQL parameter has an index of 1. ^When the same named 2576** SQL parameter is used more than once, second and subsequent 2577** occurrences have the same index as the first occurrence. 2578** ^The index for named parameters can be looked up using the 2579** [sqlite3_bind_parameter_index()] API if desired. ^The index 2580** for "?NNN" parameters is the value of NNN. 2581** ^The NNN value must be between 1 and the [sqlite3_limit()] 2582** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999). 2583** 2584** ^The third argument is the value to bind to the parameter. 2585** 2586** ^(In those routines that have a fourth argument, its value is the 2587** number of bytes in the parameter. To be clear: the value is the 2588** number of <u>bytes</u> in the value, not the number of characters.)^ 2589** ^If the fourth parameter is negative, the length of the string is 2590** the number of bytes up to the first zero terminator. 2591** 2592** ^The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and 2593** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or 2594** string after SQLite has finished with it. ^If the fifth argument is 2595** the special value [SQLITE_STATIC], then SQLite assumes that the 2596** information is in static, unmanaged space and does not need to be freed. 2597** ^If the fifth argument has the value [SQLITE_TRANSIENT], then 2598** SQLite makes its own private copy of the data immediately, before 2599** the sqlite3_bind_*() routine returns. 2600** 2601** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that 2602** is filled with zeroes. ^A zeroblob uses a fixed amount of memory 2603** (just an integer to hold its size) while it is being processed. 2604** Zeroblobs are intended to serve as placeholders for BLOBs whose 2605** content is later written using 2606** [sqlite3_blob_open | incremental BLOB I/O] routines. 2607** ^A negative value for the zeroblob results in a zero-length BLOB. 2608** 2609** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer 2610** for the [prepared statement] or with a prepared statement for which 2611** [sqlite3_step()] has been called more recently than [sqlite3_reset()], 2612** then the call will return [SQLITE_MISUSE]. If any sqlite3_bind_() 2613** routine is passed a [prepared statement] that has been finalized, the 2614** result is undefined and probably harmful. 2615** 2616** ^Bindings are not cleared by the [sqlite3_reset()] routine. 2617** ^Unbound parameters are interpreted as NULL. 2618** 2619** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an 2620** [error code] if anything goes wrong. 2621** ^[SQLITE_RANGE] is returned if the parameter 2622** index is out of range. ^[SQLITE_NOMEM] is returned if malloc() fails. 2623** 2624** See also: [sqlite3_bind_parameter_count()], 2625** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()]. 2626*/ 2627SQLITE_API int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*)); 2628SQLITE_API int sqlite3_bind_double(sqlite3_stmt*, int, double); 2629SQLITE_API int sqlite3_bind_int(sqlite3_stmt*, int, int); 2630SQLITE_API int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64); 2631SQLITE_API int sqlite3_bind_null(sqlite3_stmt*, int); 2632SQLITE_API int sqlite3_bind_text(sqlite3_stmt*, int, const char*, int n, void(*)(void*)); 2633SQLITE_API int sqlite3_bind_text16(sqlite3_stmt*, int, const void*, int, void(*)(void*)); 2634SQLITE_API int sqlite3_bind_value(sqlite3_stmt*, int, const sqlite3_value*); 2635SQLITE_API int sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n); 2636 2637/* 2638** CAPI3REF: Number Of SQL Parameters 2639** 2640** ^This routine can be used to find the number of [SQL parameters] 2641** in a [prepared statement]. SQL parameters are tokens of the 2642** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as 2643** placeholders for values that are [sqlite3_bind_blob | bound] 2644** to the parameters at a later time. 2645** 2646** ^(This routine actually returns the index of the largest (rightmost) 2647** parameter. For all forms except ?NNN, this will correspond to the 2648** number of unique parameters. If parameters of the ?NNN form are used, 2649** there may be gaps in the list.)^ 2650** 2651** See also: [sqlite3_bind_blob|sqlite3_bind()], 2652** [sqlite3_bind_parameter_name()], and 2653** [sqlite3_bind_parameter_index()]. 2654*/ 2655SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt*); 2656 2657/* 2658** CAPI3REF: Name Of A Host Parameter 2659** 2660** ^The sqlite3_bind_parameter_name(P,N) interface returns 2661** the name of the N-th [SQL parameter] in the [prepared statement] P. 2662** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA" 2663** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA" 2664** respectively. 2665** In other words, the initial ":" or "$" or "@" or "?" 2666** is included as part of the name.)^ 2667** ^Parameters of the form "?" without a following integer have no name 2668** and are referred to as "nameless" or "anonymous parameters". 2669** 2670** ^The first host parameter has an index of 1, not 0. 2671** 2672** ^If the value N is out of range or if the N-th parameter is 2673** nameless, then NULL is returned. ^The returned string is 2674** always in UTF-8 encoding even if the named parameter was 2675** originally specified as UTF-16 in [sqlite3_prepare16()] or 2676** [sqlite3_prepare16_v2()]. 2677** 2678** See also: [sqlite3_bind_blob|sqlite3_bind()], 2679** [sqlite3_bind_parameter_count()], and 2680** [sqlite3_bind_parameter_index()]. 2681*/ 2682SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt*, int); 2683 2684/* 2685** CAPI3REF: Index Of A Parameter With A Given Name 2686** 2687** ^Return the index of an SQL parameter given its name. ^The 2688** index value returned is suitable for use as the second 2689** parameter to [sqlite3_bind_blob|sqlite3_bind()]. ^A zero 2690** is returned if no matching parameter is found. ^The parameter 2691** name must be given in UTF-8 even if the original statement 2692** was prepared from UTF-16 text using [sqlite3_prepare16_v2()]. 2693** 2694** See also: [sqlite3_bind_blob|sqlite3_bind()], 2695** [sqlite3_bind_parameter_count()], and 2696** [sqlite3_bind_parameter_index()]. 2697*/ 2698SQLITE_API int sqlite3_bind_parameter_index(sqlite3_stmt*, const char *zName); 2699 2700/* 2701** CAPI3REF: Reset All Bindings On A Prepared Statement 2702** 2703** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset 2704** the [sqlite3_bind_blob | bindings] on a [prepared statement]. 2705** ^Use this routine to reset all host parameters to NULL. 2706*/ 2707SQLITE_API int sqlite3_clear_bindings(sqlite3_stmt*); 2708 2709/* 2710** CAPI3REF: Number Of Columns In A Result Set 2711** 2712** ^Return the number of columns in the result set returned by the 2713** [prepared statement]. ^This routine returns 0 if pStmt is an SQL 2714** statement that does not return data (for example an [UPDATE]). 2715*/ 2716SQLITE_API int sqlite3_column_count(sqlite3_stmt *pStmt); 2717 2718/* 2719** CAPI3REF: Column Names In A Result Set 2720** 2721** ^These routines return the name assigned to a particular column 2722** in the result set of a [SELECT] statement. ^The sqlite3_column_name() 2723** interface returns a pointer to a zero-terminated UTF-8 string 2724** and sqlite3_column_name16() returns a pointer to a zero-terminated 2725** UTF-16 string. ^The first parameter is the [prepared statement] 2726** that implements the [SELECT] statement. ^The second parameter is the 2727** column number. ^The leftmost column is number 0. 2728** 2729** ^The returned string pointer is valid until either the [prepared statement] 2730** is destroyed by [sqlite3_finalize()] or until the next call to 2731** sqlite3_column_name() or sqlite3_column_name16() on the same column. 2732** 2733** ^If sqlite3_malloc() fails during the processing of either routine 2734** (for example during a conversion from UTF-8 to UTF-16) then a 2735** NULL pointer is returned. 2736** 2737** ^The name of a result column is the value of the "AS" clause for 2738** that column, if there is an AS clause. If there is no AS clause 2739** then the name of the column is unspecified and may change from 2740** one release of SQLite to the next. 2741*/ 2742SQLITE_API const char *sqlite3_column_name(sqlite3_stmt*, int N); 2743SQLITE_API const void *sqlite3_column_name16(sqlite3_stmt*, int N); 2744 2745/* 2746** CAPI3REF: Source Of Data In A Query Result 2747** 2748** ^These routines provide a means to determine the database, table, and 2749** table column that is the origin of a particular result column in 2750** [SELECT] statement. 2751** ^The name of the database or table or column can be returned as 2752** either a UTF-8 or UTF-16 string. ^The _database_ routines return 2753** the database name, the _table_ routines return the table name, and 2754** the origin_ routines return the column name. 2755** ^The returned string is valid until the [prepared statement] is destroyed 2756** using [sqlite3_finalize()] or until the same information is requested 2757** again in a different encoding. 2758** 2759** ^The names returned are the original un-aliased names of the 2760** database, table, and column. 2761** 2762** ^The first argument to these interfaces is a [prepared statement]. 2763** ^These functions return information about the Nth result column returned by 2764** the statement, where N is the second function argument. 2765** ^The left-most column is column 0 for these routines. 2766** 2767** ^If the Nth column returned by the statement is an expression or 2768** subquery and is not a column value, then all of these functions return 2769** NULL. ^These routine might also return NULL if a memory allocation error 2770** occurs. ^Otherwise, they return the name of the attached database, table, 2771** or column that query result column was extracted from. 2772** 2773** ^As with all other SQLite APIs, those whose names end with "16" return 2774** UTF-16 encoded strings and the other functions return UTF-8. 2775** 2776** ^These APIs are only available if the library was compiled with the 2777** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol. 2778** 2779** If two or more threads call one or more of these routines against the same 2780** prepared statement and column at the same time then the results are 2781** undefined. 2782** 2783** If two or more threads call one or more 2784** [sqlite3_column_database_name | column metadata interfaces] 2785** for the same [prepared statement] and result column 2786** at the same time then the results are undefined. 2787*/ 2788SQLITE_API const char *sqlite3_column_database_name(sqlite3_stmt*,int); 2789SQLITE_API const void *sqlite3_column_database_name16(sqlite3_stmt*,int); 2790SQLITE_API const char *sqlite3_column_table_name(sqlite3_stmt*,int); 2791SQLITE_API const void *sqlite3_column_table_name16(sqlite3_stmt*,int); 2792SQLITE_API const char *sqlite3_column_origin_name(sqlite3_stmt*,int); 2793SQLITE_API const void *sqlite3_column_origin_name16(sqlite3_stmt*,int); 2794 2795/* 2796** CAPI3REF: Declared Datatype Of A Query Result 2797** 2798** ^(The first parameter is a [prepared statement]. 2799** If this statement is a [SELECT] statement and the Nth column of the 2800** returned result set of that [SELECT] is a table column (not an 2801** expression or subquery) then the declared type of the table 2802** column is returned.)^ ^If the Nth column of the result set is an 2803** expression or subquery, then a NULL pointer is returned. 2804** ^The returned string is always UTF-8 encoded. 2805** 2806** ^(For example, given the database schema: 2807** 2808** CREATE TABLE t1(c1 VARIANT); 2809** 2810** and the following statement to be compiled: 2811** 2812** SELECT c1 + 1, c1 FROM t1; 2813** 2814** this routine would return the string "VARIANT" for the second result 2815** column (i==1), and a NULL pointer for the first result column (i==0).)^ 2816** 2817** ^SQLite uses dynamic run-time typing. ^So just because a column 2818** is declared to contain a particular type does not mean that the 2819** data stored in that column is of the declared type. SQLite is 2820** strongly typed, but the typing is dynamic not static. ^Type 2821** is associated with individual values, not with the containers 2822** used to hold those values. 2823*/ 2824SQLITE_API const char *sqlite3_column_decltype(sqlite3_stmt*,int); 2825SQLITE_API const void *sqlite3_column_decltype16(sqlite3_stmt*,int); 2826 2827/* 2828** CAPI3REF: Evaluate An SQL Statement 2829** 2830** After a [prepared statement] has been prepared using either 2831** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy 2832** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function 2833** must be called one or more times to evaluate the statement. 2834** 2835** The details of the behavior of the sqlite3_step() interface depend 2836** on whether the statement was prepared using the newer "v2" interface 2837** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy 2838** interface [sqlite3_prepare()] and [sqlite3_prepare16()]. The use of the 2839** new "v2" interface is recommended for new applications but the legacy 2840** interface will continue to be supported. 2841** 2842** ^In the legacy interface, the return value will be either [SQLITE_BUSY], 2843** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE]. 2844** ^With the "v2" interface, any of the other [result codes] or 2845** [extended result codes] might be returned as well. 2846** 2847** ^[SQLITE_BUSY] means that the database engine was unable to acquire the 2848** database locks it needs to do its job. ^If the statement is a [COMMIT] 2849** or occurs outside of an explicit transaction, then you can retry the 2850** statement. If the statement is not a [COMMIT] and occurs within a 2851** explicit transaction then you should rollback the transaction before 2852** continuing. 2853** 2854** ^[SQLITE_DONE] means that the statement has finished executing 2855** successfully. sqlite3_step() should not be called again on this virtual 2856** machine without first calling [sqlite3_reset()] to reset the virtual 2857** machine back to its initial state. 2858** 2859** ^If the SQL statement being executed returns any data, then [SQLITE_ROW] 2860** is returned each time a new row of data is ready for processing by the 2861** caller. The values may be accessed using the [column access functions]. 2862** sqlite3_step() is called again to retrieve the next row of data. 2863** 2864** ^[SQLITE_ERROR] means that a run-time error (such as a constraint 2865** violation) has occurred. sqlite3_step() should not be called again on 2866** the VM. More information may be found by calling [sqlite3_errmsg()]. 2867** ^With the legacy interface, a more specific error code (for example, 2868** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth) 2869** can be obtained by calling [sqlite3_reset()] on the 2870** [prepared statement]. ^In the "v2" interface, 2871** the more specific error code is returned directly by sqlite3_step(). 2872** 2873** [SQLITE_MISUSE] means that the this routine was called inappropriately. 2874** Perhaps it was called on a [prepared statement] that has 2875** already been [sqlite3_finalize | finalized] or on one that had 2876** previously returned [SQLITE_ERROR] or [SQLITE_DONE]. Or it could 2877** be the case that the same database connection is being used by two or 2878** more threads at the same moment in time. 2879** 2880** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step() 2881** API always returns a generic error code, [SQLITE_ERROR], following any 2882** error other than [SQLITE_BUSY] and [SQLITE_MISUSE]. You must call 2883** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the 2884** specific [error codes] that better describes the error. 2885** We admit that this is a goofy design. The problem has been fixed 2886** with the "v2" interface. If you prepare all of your SQL statements 2887** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead 2888** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces, 2889** then the more specific [error codes] are returned directly 2890** by sqlite3_step(). The use of the "v2" interface is recommended. 2891*/ 2892SQLITE_API int sqlite3_step(sqlite3_stmt*); 2893 2894/* 2895** CAPI3REF: Number of columns in a result set 2896** 2897** ^The sqlite3_data_count(P) the number of columns in the 2898** of the result set of [prepared statement] P. 2899*/ 2900SQLITE_API int sqlite3_data_count(sqlite3_stmt *pStmt); 2901 2902/* 2903** CAPI3REF: Fundamental Datatypes 2904** KEYWORDS: SQLITE_TEXT 2905** 2906** ^(Every value in SQLite has one of five fundamental datatypes: 2907** 2908** <ul> 2909** <li> 64-bit signed integer 2910** <li> 64-bit IEEE floating point number 2911** <li> string 2912** <li> BLOB 2913** <li> NULL 2914** </ul>)^ 2915** 2916** These constants are codes for each of those types. 2917** 2918** Note that the SQLITE_TEXT constant was also used in SQLite version 2 2919** for a completely different meaning. Software that links against both 2920** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not 2921** SQLITE_TEXT. 2922*/ 2923#define SQLITE_INTEGER 1 2924#define SQLITE_FLOAT 2 2925#define SQLITE_BLOB 4 2926#define SQLITE_NULL 5 2927#ifdef SQLITE_TEXT 2928# undef SQLITE_TEXT 2929#else 2930# define SQLITE_TEXT 3 2931#endif 2932#define SQLITE3_TEXT 3 2933 2934/* 2935** CAPI3REF: Result Values From A Query 2936** KEYWORDS: {column access functions} 2937** 2938** These routines form the "result set" interface. 2939** 2940** ^These routines return information about a single column of the current 2941** result row of a query. ^In every case the first argument is a pointer 2942** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*] 2943** that was returned from [sqlite3_prepare_v2()] or one of its variants) 2944** and the second argument is the index of the column for which information 2945** should be returned. ^The leftmost column of the result set has the index 0. 2946** ^The number of columns in the result can be determined using 2947** [sqlite3_column_count()]. 2948** 2949** If the SQL statement does not currently point to a valid row, or if the 2950** column index is out of range, the result is undefined. 2951** These routines may only be called when the most recent call to 2952** [sqlite3_step()] has returned [SQLITE_ROW] and neither 2953** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently. 2954** If any of these routines are called after [sqlite3_reset()] or 2955** [sqlite3_finalize()] or after [sqlite3_step()] has returned 2956** something other than [SQLITE_ROW], the results are undefined. 2957** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()] 2958** are called from a different thread while any of these routines 2959** are pending, then the results are undefined. 2960** 2961** ^The sqlite3_column_type() routine returns the 2962** [SQLITE_INTEGER | datatype code] for the initial data type 2963** of the result column. ^The returned value is one of [SQLITE_INTEGER], 2964** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL]. The value 2965** returned by sqlite3_column_type() is only meaningful if no type 2966** conversions have occurred as described below. After a type conversion, 2967** the value returned by sqlite3_column_type() is undefined. Future 2968** versions of SQLite may change the behavior of sqlite3_column_type() 2969** following a type conversion. 2970** 2971** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes() 2972** routine returns the number of bytes in that BLOB or string. 2973** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts 2974** the string to UTF-8 and then returns the number of bytes. 2975** ^If the result is a numeric value then sqlite3_column_bytes() uses 2976** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns 2977** the number of bytes in that string. 2978** ^The value returned does not include the zero terminator at the end 2979** of the string. ^For clarity: the value returned is the number of 2980** bytes in the string, not the number of characters. 2981** 2982** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(), 2983** even empty strings, are always zero terminated. ^The return 2984** value from sqlite3_column_blob() for a zero-length BLOB is an arbitrary 2985** pointer, possibly even a NULL pointer. 2986** 2987** ^The sqlite3_column_bytes16() routine is similar to sqlite3_column_bytes() 2988** but leaves the result in UTF-16 in native byte order instead of UTF-8. 2989** ^The zero terminator is not included in this count. 2990** 2991** ^The object returned by [sqlite3_column_value()] is an 2992** [unprotected sqlite3_value] object. An unprotected sqlite3_value object 2993** may only be used with [sqlite3_bind_value()] and [sqlite3_result_value()]. 2994** If the [unprotected sqlite3_value] object returned by 2995** [sqlite3_column_value()] is used in any other way, including calls 2996** to routines like [sqlite3_value_int()], [sqlite3_value_text()], 2997** or [sqlite3_value_bytes()], then the behavior is undefined. 2998** 2999** These routines attempt to convert the value where appropriate. ^For 3000** example, if the internal representation is FLOAT and a text result 3001** is requested, [sqlite3_snprintf()] is used internally to perform the 3002** conversion automatically. ^(The following table details the conversions 3003** that are applied: 3004** 3005** <blockquote> 3006** <table border="1"> 3007** <tr><th> Internal<br>Type <th> Requested<br>Type <th> Conversion 3008** 3009** <tr><td> NULL <td> INTEGER <td> Result is 0 3010** <tr><td> NULL <td> FLOAT <td> Result is 0.0 3011** <tr><td> NULL <td> TEXT <td> Result is NULL pointer 3012** <tr><td> NULL <td> BLOB <td> Result is NULL pointer 3013** <tr><td> INTEGER <td> FLOAT <td> Convert from integer to float 3014** <tr><td> INTEGER <td> TEXT <td> ASCII rendering of the integer 3015** <tr><td> INTEGER <td> BLOB <td> Same as INTEGER->TEXT 3016** <tr><td> FLOAT <td> INTEGER <td> Convert from float to integer 3017** <tr><td> FLOAT <td> TEXT <td> ASCII rendering of the float 3018** <tr><td> FLOAT <td> BLOB <td> Same as FLOAT->TEXT 3019** <tr><td> TEXT <td> INTEGER <td> Use atoi() 3020** <tr><td> TEXT <td> FLOAT <td> Use atof() 3021** <tr><td> TEXT <td> BLOB <td> No change 3022** <tr><td> BLOB <td> INTEGER <td> Convert to TEXT then use atoi() 3023** <tr><td> BLOB <td> FLOAT <td> Convert to TEXT then use atof() 3024** <tr><td> BLOB <td> TEXT <td> Add a zero terminator if needed 3025** </table> 3026** </blockquote>)^ 3027** 3028** The table above makes reference to standard C library functions atoi() 3029** and atof(). SQLite does not really use these functions. It has its 3030** own equivalent internal routines. The atoi() and atof() names are 3031** used in the table for brevity and because they are familiar to most 3032** C programmers. 3033** 3034** ^Note that when type conversions occur, pointers returned by prior 3035** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or 3036** sqlite3_column_text16() may be invalidated. 3037** ^(Type conversions and pointer invalidations might occur 3038** in the following cases: 3039** 3040** <ul> 3041** <li> The initial content is a BLOB and sqlite3_column_text() or 3042** sqlite3_column_text16() is called. A zero-terminator might 3043** need to be added to the string.</li> 3044** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or 3045** sqlite3_column_text16() is called. The content must be converted 3046** to UTF-16.</li> 3047** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or 3048** sqlite3_column_text() is called. The content must be converted 3049** to UTF-8.</li> 3050** </ul>)^ 3051** 3052** ^Conversions between UTF-16be and UTF-16le are always done in place and do 3053** not invalidate a prior pointer, though of course the content of the buffer 3054** that the prior pointer points to will have been modified. Other kinds 3055** of conversion are done in place when it is possible, but sometimes they 3056** are not possible and in those cases prior pointers are invalidated. 3057** 3058** ^(The safest and easiest to remember policy is to invoke these routines 3059** in one of the following ways: 3060** 3061** <ul> 3062** <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li> 3063** <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li> 3064** <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li> 3065** </ul>)^ 3066** 3067** In other words, you should call sqlite3_column_text(), 3068** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result 3069** into the desired format, then invoke sqlite3_column_bytes() or 3070** sqlite3_column_bytes16() to find the size of the result. Do not mix calls 3071** to sqlite3_column_text() or sqlite3_column_blob() with calls to 3072** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16() 3073** with calls to sqlite3_column_bytes(). 3074** 3075** ^The pointers returned are valid until a type conversion occurs as 3076** described above, or until [sqlite3_step()] or [sqlite3_reset()] or 3077** [sqlite3_finalize()] is called. ^The memory space used to hold strings 3078** and BLOBs is freed automatically. Do <b>not</b> pass the pointers returned 3079** [sqlite3_column_blob()], [sqlite3_column_text()], etc. into 3080** [sqlite3_free()]. 3081** 3082** ^(If a memory allocation error occurs during the evaluation of any 3083** of these routines, a default value is returned. The default value 3084** is either the integer 0, the floating point number 0.0, or a NULL 3085** pointer. Subsequent calls to [sqlite3_errcode()] will return 3086** [SQLITE_NOMEM].)^ 3087*/ 3088SQLITE_API const void *sqlite3_column_blob(sqlite3_stmt*, int iCol); 3089SQLITE_API int sqlite3_column_bytes(sqlite3_stmt*, int iCol); 3090SQLITE_API int sqlite3_column_bytes16(sqlite3_stmt*, int iCol); 3091SQLITE_API double sqlite3_column_double(sqlite3_stmt*, int iCol); 3092SQLITE_API int sqlite3_column_int(sqlite3_stmt*, int iCol); 3093SQLITE_API sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol); 3094SQLITE_API const unsigned char *sqlite3_column_text(sqlite3_stmt*, int iCol); 3095SQLITE_API const void *sqlite3_column_text16(sqlite3_stmt*, int iCol); 3096SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol); 3097SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol); 3098 3099/* 3100** CAPI3REF: Destroy A Prepared Statement Object 3101** 3102** ^The sqlite3_finalize() function is called to delete a [prepared statement]. 3103** ^If the statement was executed successfully or not executed at all, then 3104** SQLITE_OK is returned. ^If execution of the statement failed then an 3105** [error code] or [extended error code] is returned. 3106** 3107** ^This routine can be called at any point during the execution of the 3108** [prepared statement]. ^If the virtual machine has not 3109** completed execution when this routine is called, that is like 3110** encountering an error or an [sqlite3_interrupt | interrupt]. 3111** ^Incomplete updates may be rolled back and transactions canceled, 3112** depending on the circumstances, and the 3113** [error code] returned will be [SQLITE_ABORT]. 3114*/ 3115SQLITE_API int sqlite3_finalize(sqlite3_stmt *pStmt); 3116 3117/* 3118** CAPI3REF: Reset A Prepared Statement Object 3119** 3120** The sqlite3_reset() function is called to reset a [prepared statement] 3121** object back to its initial state, ready to be re-executed. 3122** ^Any SQL statement variables that had values bound to them using 3123** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values. 3124** Use [sqlite3_clear_bindings()] to reset the bindings. 3125** 3126** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S 3127** back to the beginning of its program. 3128** 3129** ^If the most recent call to [sqlite3_step(S)] for the 3130** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE], 3131** or if [sqlite3_step(S)] has never before been called on S, 3132** then [sqlite3_reset(S)] returns [SQLITE_OK]. 3133** 3134** ^If the most recent call to [sqlite3_step(S)] for the 3135** [prepared statement] S indicated an error, then 3136** [sqlite3_reset(S)] returns an appropriate [error code]. 3137** 3138** ^The [sqlite3_reset(S)] interface does not change the values 3139** of any [sqlite3_bind_blob|bindings] on the [prepared statement] S. 3140*/ 3141SQLITE_API int sqlite3_reset(sqlite3_stmt *pStmt); 3142 3143/* 3144** CAPI3REF: Create Or Redefine SQL Functions 3145** KEYWORDS: {function creation routines} 3146** KEYWORDS: {application-defined SQL function} 3147** KEYWORDS: {application-defined SQL functions} 3148** 3149** ^These two functions (collectively known as "function creation routines") 3150** are used to add SQL functions or aggregates or to redefine the behavior 3151** of existing SQL functions or aggregates. The only difference between the 3152** two is that the second parameter, the name of the (scalar) function or 3153** aggregate, is encoded in UTF-8 for sqlite3_create_function() and UTF-16 3154** for sqlite3_create_function16(). 3155** 3156** ^The first parameter is the [database connection] to which the SQL 3157** function is to be added. ^If an application uses more than one database 3158** connection then application-defined SQL functions must be added 3159** to each database connection separately. 3160** 3161** The second parameter is the name of the SQL function to be created or 3162** redefined. ^The length of the name is limited to 255 bytes, exclusive of 3163** the zero-terminator. Note that the name length limit is in bytes, not 3164** characters. ^Any attempt to create a function with a longer name 3165** will result in [SQLITE_ERROR] being returned. 3166** 3167** ^The third parameter (nArg) 3168** is the number of arguments that the SQL function or 3169** aggregate takes. ^If this parameter is -1, then the SQL function or 3170** aggregate may take any number of arguments between 0 and the limit 3171** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]). If the third 3172** parameter is less than -1 or greater than 127 then the behavior is 3173** undefined. 3174** 3175** The fourth parameter, eTextRep, specifies what 3176** [SQLITE_UTF8 | text encoding] this SQL function prefers for 3177** its parameters. Any SQL function implementation should be able to work 3178** work with UTF-8, UTF-16le, or UTF-16be. But some implementations may be 3179** more efficient with one encoding than another. ^An application may 3180** invoke sqlite3_create_function() or sqlite3_create_function16() multiple 3181** times with the same function but with different values of eTextRep. 3182** ^When multiple implementations of the same function are available, SQLite 3183** will pick the one that involves the least amount of data conversion. 3184** If there is only a single implementation which does not care what text 3185** encoding is used, then the fourth argument should be [SQLITE_ANY]. 3186** 3187** ^(The fifth parameter is an arbitrary pointer. The implementation of the 3188** function can gain access to this pointer using [sqlite3_user_data()].)^ 3189** 3190** The seventh, eighth and ninth parameters, xFunc, xStep and xFinal, are 3191** pointers to C-language functions that implement the SQL function or 3192** aggregate. ^A scalar SQL function requires an implementation of the xFunc 3193** callback only; NULL pointers should be passed as the xStep and xFinal 3194** parameters. ^An aggregate SQL function requires an implementation of xStep 3195** and xFinal and NULL should be passed for xFunc. ^To delete an existing 3196** SQL function or aggregate, pass NULL for all three function callbacks. 3197** 3198** ^It is permitted to register multiple implementations of the same 3199** functions with the same name but with either differing numbers of 3200** arguments or differing preferred text encodings. ^SQLite will use 3201** the implementation that most closely matches the way in which the 3202** SQL function is used. ^A function implementation with a non-negative 3203** nArg parameter is a better match than a function implementation with 3204** a negative nArg. ^A function where the preferred text encoding 3205** matches the database encoding is a better 3206** match than a function where the encoding is different. 3207** ^A function where the encoding difference is between UTF16le and UTF16be 3208** is a closer match than a function where the encoding difference is 3209** between UTF8 and UTF16. 3210** 3211** ^Built-in functions may be overloaded by new application-defined functions. 3212** ^The first application-defined function with a given name overrides all 3213** built-in functions in the same [database connection] with the same name. 3214** ^Subsequent application-defined functions of the same name only override 3215** prior application-defined functions that are an exact match for the 3216** number of parameters and preferred encoding. 3217** 3218** ^An application-defined function is permitted to call other 3219** SQLite interfaces. However, such calls must not 3220** close the database connection nor finalize or reset the prepared 3221** statement in which the function is running. 3222*/ 3223SQLITE_API int sqlite3_create_function( 3224 sqlite3 *db, 3225 const char *zFunctionName, 3226 int nArg, 3227 int eTextRep, 3228 void *pApp, 3229 void (*xFunc)(sqlite3_context*,int,sqlite3_value**), 3230 void (*xStep)(sqlite3_context*,int,sqlite3_value**), 3231 void (*xFinal)(sqlite3_context*) 3232); 3233SQLITE_API int sqlite3_create_function16( 3234 sqlite3 *db, 3235 const void *zFunctionName, 3236 int nArg, 3237 int eTextRep, 3238 void *pApp, 3239 void (*xFunc)(sqlite3_context*,int,sqlite3_value**), 3240 void (*xStep)(sqlite3_context*,int,sqlite3_value**), 3241 void (*xFinal)(sqlite3_context*) 3242); 3243 3244/* 3245** CAPI3REF: Text Encodings 3246** 3247** These constant define integer codes that represent the various 3248** text encodings supported by SQLite. 3249*/ 3250#define SQLITE_UTF8 1 3251#define SQLITE_UTF16LE 2 3252#define SQLITE_UTF16BE 3 3253#define SQLITE_UTF16 4 /* Use native byte order */ 3254#define SQLITE_ANY 5 /* sqlite3_create_function only */ 3255#define SQLITE_UTF16_ALIGNED 8 /* sqlite3_create_collation only */ 3256 3257/* 3258** CAPI3REF: Deprecated Functions 3259** DEPRECATED 3260** 3261** These functions are [deprecated]. In order to maintain 3262** backwards compatibility with older code, these functions continue 3263** to be supported. However, new applications should avoid 3264** the use of these functions. To help encourage people to avoid 3265** using these functions, we are not going to tell you what they do. 3266*/ 3267#ifndef SQLITE_OMIT_DEPRECATED 3268SQLITE_API SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*); 3269SQLITE_API SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*); 3270SQLITE_API SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt*, sqlite3_stmt*); 3271SQLITE_API SQLITE_DEPRECATED int sqlite3_global_recover(void); 3272SQLITE_API SQLITE_DEPRECATED void sqlite3_thread_cleanup(void); 3273SQLITE_API SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),void*,sqlite3_int64); 3274#endif 3275 3276/* 3277** CAPI3REF: Obtaining SQL Function Parameter Values 3278** 3279** The C-language implementation of SQL functions and aggregates uses 3280** this set of interface routines to access the parameter values on 3281** the function or aggregate. 3282** 3283** The xFunc (for scalar functions) or xStep (for aggregates) parameters 3284** to [sqlite3_create_function()] and [sqlite3_create_function16()] 3285** define callbacks that implement the SQL functions and aggregates. 3286** The 4th parameter to these callbacks is an array of pointers to 3287** [protected sqlite3_value] objects. There is one [sqlite3_value] object for 3288** each parameter to the SQL function. These routines are used to 3289** extract values from the [sqlite3_value] objects. 3290** 3291** These routines work only with [protected sqlite3_value] objects. 3292** Any attempt to use these routines on an [unprotected sqlite3_value] 3293** object results in undefined behavior. 3294** 3295** ^These routines work just like the corresponding [column access functions] 3296** except that these routines take a single [protected sqlite3_value] object 3297** pointer instead of a [sqlite3_stmt*] pointer and an integer column number. 3298** 3299** ^The sqlite3_value_text16() interface extracts a UTF-16 string 3300** in the native byte-order of the host machine. ^The 3301** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces 3302** extract UTF-16 strings as big-endian and little-endian respectively. 3303** 3304** ^(The sqlite3_value_numeric_type() interface attempts to apply 3305** numeric affinity to the value. This means that an attempt is 3306** made to convert the value to an integer or floating point. If 3307** such a conversion is possible without loss of information (in other 3308** words, if the value is a string that looks like a number) 3309** then the conversion is performed. Otherwise no conversion occurs. 3310** The [SQLITE_INTEGER | datatype] after conversion is returned.)^ 3311** 3312** Please pay particular attention to the fact that the pointer returned 3313** from [sqlite3_value_blob()], [sqlite3_value_text()], or 3314** [sqlite3_value_text16()] can be invalidated by a subsequent call to 3315** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()], 3316** or [sqlite3_value_text16()]. 3317** 3318** These routines must be called from the same thread as 3319** the SQL function that supplied the [sqlite3_value*] parameters. 3320*/ 3321SQLITE_API const void *sqlite3_value_blob(sqlite3_value*); 3322SQLITE_API int sqlite3_value_bytes(sqlite3_value*); 3323SQLITE_API int sqlite3_value_bytes16(sqlite3_value*); 3324SQLITE_API double sqlite3_value_double(sqlite3_value*); 3325SQLITE_API int sqlite3_value_int(sqlite3_value*); 3326SQLITE_API sqlite3_int64 sqlite3_value_int64(sqlite3_value*); 3327SQLITE_API const unsigned char *sqlite3_value_text(sqlite3_value*); 3328SQLITE_API const void *sqlite3_value_text16(sqlite3_value*); 3329SQLITE_API const void *sqlite3_value_text16le(sqlite3_value*); 3330SQLITE_API const void *sqlite3_value_text16be(sqlite3_value*); 3331SQLITE_API int sqlite3_value_type(sqlite3_value*); 3332SQLITE_API int sqlite3_value_numeric_type(sqlite3_value*); 3333 3334/* 3335** CAPI3REF: Obtain Aggregate Function Context 3336** 3337** Implementions of aggregate SQL functions use this 3338** routine to allocate memory for storing their state. 3339** 3340** ^The first time the sqlite3_aggregate_context(C,N) routine is called 3341** for a particular aggregate function, SQLite 3342** allocates N of memory, zeroes out that memory, and returns a pointer 3343** to the new memory. ^On second and subsequent calls to 3344** sqlite3_aggregate_context() for the same aggregate function instance, 3345** the same buffer is returned. Sqlite3_aggregate_context() is normally 3346** called once for each invocation of the xStep callback and then one 3347** last time when the xFinal callback is invoked. ^(When no rows match 3348** an aggregate query, the xStep() callback of the aggregate function 3349** implementation is never called and xFinal() is called exactly once. 3350** In those cases, sqlite3_aggregate_context() might be called for the 3351** first time from within xFinal().)^ 3352** 3353** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer if N is 3354** less than or equal to zero or if a memory allocate error occurs. 3355** 3356** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is 3357** determined by the N parameter on first successful call. Changing the 3358** value of N in subsequent call to sqlite3_aggregate_context() within 3359** the same aggregate function instance will not resize the memory 3360** allocation.)^ 3361** 3362** ^SQLite automatically frees the memory allocated by 3363** sqlite3_aggregate_context() when the aggregate query concludes. 3364** 3365** The first parameter must be a copy of the 3366** [sqlite3_context | SQL function context] that is the first parameter 3367** to the xStep or xFinal callback routine that implements the aggregate 3368** function. 3369** 3370** This routine must be called from the same thread in which 3371** the aggregate SQL function is running. 3372*/ 3373SQLITE_API void *sqlite3_aggregate_context(sqlite3_context*, int nBytes); 3374 3375/* 3376** CAPI3REF: User Data For Functions 3377** 3378** ^The sqlite3_user_data() interface returns a copy of 3379** the pointer that was the pUserData parameter (the 5th parameter) 3380** of the [sqlite3_create_function()] 3381** and [sqlite3_create_function16()] routines that originally 3382** registered the application defined function. 3383** 3384** This routine must be called from the same thread in which 3385** the application-defined function is running. 3386*/ 3387SQLITE_API void *sqlite3_user_data(sqlite3_context*); 3388 3389/* 3390** CAPI3REF: Database Connection For Functions 3391** 3392** ^The sqlite3_context_db_handle() interface returns a copy of 3393** the pointer to the [database connection] (the 1st parameter) 3394** of the [sqlite3_create_function()] 3395** and [sqlite3_create_function16()] routines that originally 3396** registered the application defined function. 3397*/ 3398SQLITE_API sqlite3 *sqlite3_context_db_handle(sqlite3_context*); 3399 3400/* 3401** CAPI3REF: Function Auxiliary Data 3402** 3403** The following two functions may be used by scalar SQL functions to 3404** associate metadata with argument values. If the same value is passed to 3405** multiple invocations of the same SQL function during query execution, under 3406** some circumstances the associated metadata may be preserved. This may 3407** be used, for example, to add a regular-expression matching scalar 3408** function. The compiled version of the regular expression is stored as 3409** metadata associated with the SQL value passed as the regular expression 3410** pattern. The compiled regular expression can be reused on multiple 3411** invocations of the same function so that the original pattern string 3412** does not need to be recompiled on each invocation. 3413** 3414** ^The sqlite3_get_auxdata() interface returns a pointer to the metadata 3415** associated by the sqlite3_set_auxdata() function with the Nth argument 3416** value to the application-defined function. ^If no metadata has been ever 3417** been set for the Nth argument of the function, or if the corresponding 3418** function parameter has changed since the meta-data was set, 3419** then sqlite3_get_auxdata() returns a NULL pointer. 3420** 3421** ^The sqlite3_set_auxdata() interface saves the metadata 3422** pointed to by its 3rd parameter as the metadata for the N-th 3423** argument of the application-defined function. Subsequent 3424** calls to sqlite3_get_auxdata() might return this data, if it has 3425** not been destroyed. 3426** ^If it is not NULL, SQLite will invoke the destructor 3427** function given by the 4th parameter to sqlite3_set_auxdata() on 3428** the metadata when the corresponding function parameter changes 3429** or when the SQL statement completes, whichever comes first. 3430** 3431** SQLite is free to call the destructor and drop metadata on any 3432** parameter of any function at any time. ^The only guarantee is that 3433** the destructor will be called before the metadata is dropped. 3434** 3435** ^(In practice, metadata is preserved between function calls for 3436** expressions that are constant at compile time. This includes literal 3437** values and [parameters].)^ 3438** 3439** These routines must be called from the same thread in which 3440** the SQL function is running. 3441*/ 3442SQLITE_API void *sqlite3_get_auxdata(sqlite3_context*, int N); 3443SQLITE_API void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*)); 3444 3445 3446/* 3447** CAPI3REF: Constants Defining Special Destructor Behavior 3448** 3449** These are special values for the destructor that is passed in as the 3450** final argument to routines like [sqlite3_result_blob()]. ^If the destructor 3451** argument is SQLITE_STATIC, it means that the content pointer is constant 3452** and will never change. It does not need to be destroyed. ^The 3453** SQLITE_TRANSIENT value means that the content will likely change in 3454** the near future and that SQLite should make its own private copy of 3455** the content before returning. 3456** 3457** The typedef is necessary to work around problems in certain 3458** C++ compilers. See ticket #2191. 3459*/ 3460typedef void (*sqlite3_destructor_type)(void*); 3461#define SQLITE_STATIC ((sqlite3_destructor_type)0) 3462#define SQLITE_TRANSIENT ((sqlite3_destructor_type)-1) 3463 3464/* 3465** CAPI3REF: Setting The Result Of An SQL Function 3466** 3467** These routines are used by the xFunc or xFinal callbacks that 3468** implement SQL functions and aggregates. See 3469** [sqlite3_create_function()] and [sqlite3_create_function16()] 3470** for additional information. 3471** 3472** These functions work very much like the [parameter binding] family of 3473** functions used to bind values to host parameters in prepared statements. 3474** Refer to the [SQL parameter] documentation for additional information. 3475** 3476** ^The sqlite3_result_blob() interface sets the result from 3477** an application-defined function to be the BLOB whose content is pointed 3478** to by the second parameter and which is N bytes long where N is the 3479** third parameter. 3480** 3481** ^The sqlite3_result_zeroblob() interfaces set the result of 3482** the application-defined function to be a BLOB containing all zero 3483** bytes and N bytes in size, where N is the value of the 2nd parameter. 3484** 3485** ^The sqlite3_result_double() interface sets the result from 3486** an application-defined function to be a floating point value specified 3487** by its 2nd argument. 3488** 3489** ^The sqlite3_result_error() and sqlite3_result_error16() functions 3490** cause the implemented SQL function to throw an exception. 3491** ^SQLite uses the string pointed to by the 3492** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16() 3493** as the text of an error message. ^SQLite interprets the error 3494** message string from sqlite3_result_error() as UTF-8. ^SQLite 3495** interprets the string from sqlite3_result_error16() as UTF-16 in native 3496** byte order. ^If the third parameter to sqlite3_result_error() 3497** or sqlite3_result_error16() is negative then SQLite takes as the error 3498** message all text up through the first zero character. 3499** ^If the third parameter to sqlite3_result_error() or 3500** sqlite3_result_error16() is non-negative then SQLite takes that many 3501** bytes (not characters) from the 2nd parameter as the error message. 3502** ^The sqlite3_result_error() and sqlite3_result_error16() 3503** routines make a private copy of the error message text before 3504** they return. Hence, the calling function can deallocate or 3505** modify the text after they return without harm. 3506** ^The sqlite3_result_error_code() function changes the error code 3507** returned by SQLite as a result of an error in a function. ^By default, 3508** the error code is SQLITE_ERROR. ^A subsequent call to sqlite3_result_error() 3509** or sqlite3_result_error16() resets the error code to SQLITE_ERROR. 3510** 3511** ^The sqlite3_result_toobig() interface causes SQLite to throw an error 3512** indicating that a string or BLOB is too long to represent. 3513** 3514** ^The sqlite3_result_nomem() interface causes SQLite to throw an error 3515** indicating that a memory allocation failed. 3516** 3517** ^The sqlite3_result_int() interface sets the return value 3518** of the application-defined function to be the 32-bit signed integer 3519** value given in the 2nd argument. 3520** ^The sqlite3_result_int64() interface sets the return value 3521** of the application-defined function to be the 64-bit signed integer 3522** value given in the 2nd argument. 3523** 3524** ^The sqlite3_result_null() interface sets the return value 3525** of the application-defined function to be NULL. 3526** 3527** ^The sqlite3_result_text(), sqlite3_result_text16(), 3528** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces 3529** set the return value of the application-defined function to be 3530** a text string which is represented as UTF-8, UTF-16 native byte order, 3531** UTF-16 little endian, or UTF-16 big endian, respectively. 3532** ^SQLite takes the text result from the application from 3533** the 2nd parameter of the sqlite3_result_text* interfaces. 3534** ^If the 3rd parameter to the sqlite3_result_text* interfaces 3535** is negative, then SQLite takes result text from the 2nd parameter 3536** through the first zero character. 3537** ^If the 3rd parameter to the sqlite3_result_text* interfaces 3538** is non-negative, then as many bytes (not characters) of the text 3539** pointed to by the 2nd parameter are taken as the application-defined 3540** function result. 3541** ^If the 4th parameter to the sqlite3_result_text* interfaces 3542** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that 3543** function as the destructor on the text or BLOB result when it has 3544** finished using that result. 3545** ^If the 4th parameter to the sqlite3_result_text* interfaces or to 3546** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite 3547** assumes that the text or BLOB result is in constant space and does not 3548** copy the content of the parameter nor call a destructor on the content 3549** when it has finished using that result. 3550** ^If the 4th parameter to the sqlite3_result_text* interfaces 3551** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT 3552** then SQLite makes a copy of the result into space obtained from 3553** from [sqlite3_malloc()] before it returns. 3554** 3555** ^The sqlite3_result_value() interface sets the result of 3556** the application-defined function to be a copy the 3557** [unprotected sqlite3_value] object specified by the 2nd parameter. ^The 3558** sqlite3_result_value() interface makes a copy of the [sqlite3_value] 3559** so that the [sqlite3_value] specified in the parameter may change or 3560** be deallocated after sqlite3_result_value() returns without harm. 3561** ^A [protected sqlite3_value] object may always be used where an 3562** [unprotected sqlite3_value] object is required, so either 3563** kind of [sqlite3_value] object can be used with this interface. 3564** 3565** If these routines are called from within the different thread 3566** than the one containing the application-defined function that received 3567** the [sqlite3_context] pointer, the results are undefined. 3568*/ 3569SQLITE_API void sqlite3_result_blob(sqlite3_context*, const void*, int, void(*)(void*)); 3570SQLITE_API void sqlite3_result_double(sqlite3_context*, double); 3571SQLITE_API void sqlite3_result_error(sqlite3_context*, const char*, int); 3572SQLITE_API void sqlite3_result_error16(sqlite3_context*, const void*, int); 3573SQLITE_API void sqlite3_result_error_toobig(sqlite3_context*); 3574SQLITE_API void sqlite3_result_error_nomem(sqlite3_context*); 3575SQLITE_API void sqlite3_result_error_code(sqlite3_context*, int); 3576SQLITE_API void sqlite3_result_int(sqlite3_context*, int); 3577SQLITE_API void sqlite3_result_int64(sqlite3_context*, sqlite3_int64); 3578SQLITE_API void sqlite3_result_null(sqlite3_context*); 3579SQLITE_API void sqlite3_result_text(sqlite3_context*, const char*, int, void(*)(void*)); 3580SQLITE_API void sqlite3_result_text16(sqlite3_context*, const void*, int, void(*)(void*)); 3581SQLITE_API void sqlite3_result_text16le(sqlite3_context*, const void*, int,void(*)(void*)); 3582SQLITE_API void sqlite3_result_text16be(sqlite3_context*, const void*, int,void(*)(void*)); 3583SQLITE_API void sqlite3_result_value(sqlite3_context*, sqlite3_value*); 3584SQLITE_API void sqlite3_result_zeroblob(sqlite3_context*, int n); 3585 3586/* 3587** CAPI3REF: Define New Collating Sequences 3588** 3589** These functions are used to add new collation sequences to the 3590** [database connection] specified as the first argument. 3591** 3592** ^The name of the new collation sequence is specified as a UTF-8 string 3593** for sqlite3_create_collation() and sqlite3_create_collation_v2() 3594** and a UTF-16 string for sqlite3_create_collation16(). ^In all cases 3595** the name is passed as the second function argument. 3596** 3597** ^The third argument may be one of the constants [SQLITE_UTF8], 3598** [SQLITE_UTF16LE], or [SQLITE_UTF16BE], indicating that the user-supplied 3599** routine expects to be passed pointers to strings encoded using UTF-8, 3600** UTF-16 little-endian, or UTF-16 big-endian, respectively. ^The 3601** third argument might also be [SQLITE_UTF16] to indicate that the routine 3602** expects pointers to be UTF-16 strings in the native byte order, or the 3603** argument can be [SQLITE_UTF16_ALIGNED] if the 3604** the routine expects pointers to 16-bit word aligned strings 3605** of UTF-16 in the native byte order. 3606** 3607** A pointer to the user supplied routine must be passed as the fifth 3608** argument. ^If it is NULL, this is the same as deleting the collation 3609** sequence (so that SQLite cannot call it anymore). 3610** ^Each time the application supplied function is invoked, it is passed 3611** as its first parameter a copy of the void* passed as the fourth argument 3612** to sqlite3_create_collation() or sqlite3_create_collation16(). 3613** 3614** ^The remaining arguments to the application-supplied routine are two strings, 3615** each represented by a (length, data) pair and encoded in the encoding 3616** that was passed as the third argument when the collation sequence was 3617** registered. The application defined collation routine should 3618** return negative, zero or positive if the first string is less than, 3619** equal to, or greater than the second string. i.e. (STRING1 - STRING2). 3620** 3621** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation() 3622** except that it takes an extra argument which is a destructor for 3623** the collation. ^The destructor is called when the collation is 3624** destroyed and is passed a copy of the fourth parameter void* pointer 3625** of the sqlite3_create_collation_v2(). 3626** ^Collations are destroyed when they are overridden by later calls to the 3627** collation creation functions or when the [database connection] is closed 3628** using [sqlite3_close()]. 3629** 3630** See also: [sqlite3_collation_needed()] and [sqlite3_collation_needed16()]. 3631*/ 3632SQLITE_API int sqlite3_create_collation( 3633 sqlite3*, 3634 const char *zName, 3635 int eTextRep, 3636 void*, 3637 int(*xCompare)(void*,int,const void*,int,const void*) 3638); 3639SQLITE_API int sqlite3_create_collation_v2( 3640 sqlite3*, 3641 const char *zName, 3642 int eTextRep, 3643 void*, 3644 int(*xCompare)(void*,int,const void*,int,const void*), 3645 void(*xDestroy)(void*) 3646); 3647SQLITE_API int sqlite3_create_collation16( 3648 sqlite3*, 3649 const void *zName, 3650 int eTextRep, 3651 void*, 3652 int(*xCompare)(void*,int,const void*,int,const void*) 3653); 3654 3655/* 3656** CAPI3REF: Collation Needed Callbacks 3657** 3658** ^To avoid having to register all collation sequences before a database 3659** can be used, a single callback function may be registered with the 3660** [database connection] to be invoked whenever an undefined collation 3661** sequence is required. 3662** 3663** ^If the function is registered using the sqlite3_collation_needed() API, 3664** then it is passed the names of undefined collation sequences as strings 3665** encoded in UTF-8. ^If sqlite3_collation_needed16() is used, 3666** the names are passed as UTF-16 in machine native byte order. 3667** ^A call to either function replaces the existing collation-needed callback. 3668** 3669** ^(When the callback is invoked, the first argument passed is a copy 3670** of the second argument to sqlite3_collation_needed() or 3671** sqlite3_collation_needed16(). The second argument is the database 3672** connection. The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE], 3673** or [SQLITE_UTF16LE], indicating the most desirable form of the collation 3674** sequence function required. The fourth parameter is the name of the 3675** required collation sequence.)^ 3676** 3677** The callback function should register the desired collation using 3678** [sqlite3_create_collation()], [sqlite3_create_collation16()], or 3679** [sqlite3_create_collation_v2()]. 3680*/ 3681SQLITE_API int sqlite3_collation_needed( 3682 sqlite3*, 3683 void*, 3684 void(*)(void*,sqlite3*,int eTextRep,const char*) 3685); 3686SQLITE_API int sqlite3_collation_needed16( 3687 sqlite3*, 3688 void*, 3689 void(*)(void*,sqlite3*,int eTextRep,const void*) 3690); 3691 3692#if SQLITE_HAS_CODEC 3693/* 3694** Specify the key for an encrypted database. This routine should be 3695** called right after sqlite3_open(). 3696** 3697** The code to implement this API is not available in the public release 3698** of SQLite. 3699*/ 3700SQLITE_API int sqlite3_key( 3701 sqlite3 *db, /* Database to be rekeyed */ 3702 const void *pKey, int nKey /* The key */ 3703); 3704 3705/* 3706** Change the key on an open database. If the current database is not 3707** encrypted, this routine will encrypt it. If pNew==0 or nNew==0, the 3708** database is decrypted. 3709** 3710** The code to implement this API is not available in the public release 3711** of SQLite. 3712*/ 3713SQLITE_API int sqlite3_rekey( 3714 sqlite3 *db, /* Database to be rekeyed */ 3715 const void *pKey, int nKey /* The new key */ 3716); 3717 3718/* 3719** Specify the activation key for a SEE database. Unless 3720** activated, none of the SEE routines will work. 3721*/ 3722SQLITE_API void sqlite3_activate_see( 3723 const char *zPassPhrase /* Activation phrase */ 3724); 3725#endif 3726 3727#ifdef SQLITE_ENABLE_CEROD 3728/* 3729** Specify the activation key for a CEROD database. Unless 3730** activated, none of the CEROD routines will work. 3731*/ 3732SQLITE_API void sqlite3_activate_cerod( 3733 const char *zPassPhrase /* Activation phrase */ 3734); 3735#endif 3736 3737/* 3738** CAPI3REF: Suspend Execution For A Short Time 3739** 3740** ^The sqlite3_sleep() function causes the current thread to suspend execution 3741** for at least a number of milliseconds specified in its parameter. 3742** 3743** ^If the operating system does not support sleep requests with 3744** millisecond time resolution, then the time will be rounded up to 3745** the nearest second. ^The number of milliseconds of sleep actually 3746** requested from the operating system is returned. 3747** 3748** ^SQLite implements this interface by calling the xSleep() 3749** method of the default [sqlite3_vfs] object. 3750*/ 3751SQLITE_API int sqlite3_sleep(int); 3752 3753/* 3754** CAPI3REF: Name Of The Folder Holding Temporary Files 3755** 3756** ^(If this global variable is made to point to a string which is 3757** the name of a folder (a.k.a. directory), then all temporary files 3758** created by SQLite when using a built-in [sqlite3_vfs | VFS] 3759** will be placed in that directory.)^ ^If this variable 3760** is a NULL pointer, then SQLite performs a search for an appropriate 3761** temporary file directory. 3762** 3763** It is not safe to read or modify this variable in more than one 3764** thread at a time. It is not safe to read or modify this variable 3765** if a [database connection] is being used at the same time in a separate 3766** thread. 3767** It is intended that this variable be set once 3768** as part of process initialization and before any SQLite interface 3769** routines have been called and that this variable remain unchanged 3770** thereafter. 3771** 3772** ^The [temp_store_directory pragma] may modify this variable and cause 3773** it to point to memory obtained from [sqlite3_malloc]. ^Furthermore, 3774** the [temp_store_directory pragma] always assumes that any string 3775** that this variable points to is held in memory obtained from 3776** [sqlite3_malloc] and the pragma may attempt to free that memory 3777** using [sqlite3_free]. 3778** Hence, if this variable is modified directly, either it should be 3779** made NULL or made to point to memory obtained from [sqlite3_malloc] 3780** or else the use of the [temp_store_directory pragma] should be avoided. 3781*/ 3782SQLITE_API SQLITE_EXTERN char *sqlite3_temp_directory; 3783 3784/* 3785** CAPI3REF: Test For Auto-Commit Mode 3786** KEYWORDS: {autocommit mode} 3787** 3788** ^The sqlite3_get_autocommit() interface returns non-zero or 3789** zero if the given database connection is or is not in autocommit mode, 3790** respectively. ^Autocommit mode is on by default. 3791** ^Autocommit mode is disabled by a [BEGIN] statement. 3792** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK]. 3793** 3794** If certain kinds of errors occur on a statement within a multi-statement 3795** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR], 3796** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the 3797** transaction might be rolled back automatically. The only way to 3798** find out whether SQLite automatically rolled back the transaction after 3799** an error is to use this function. 3800** 3801** If another thread changes the autocommit status of the database 3802** connection while this routine is running, then the return value 3803** is undefined. 3804*/ 3805SQLITE_API int sqlite3_get_autocommit(sqlite3*); 3806 3807/* 3808** CAPI3REF: Find The Database Handle Of A Prepared Statement 3809** 3810** ^The sqlite3_db_handle interface returns the [database connection] handle 3811** to which a [prepared statement] belongs. ^The [database connection] 3812** returned by sqlite3_db_handle is the same [database connection] 3813** that was the first argument 3814** to the [sqlite3_prepare_v2()] call (or its variants) that was used to 3815** create the statement in the first place. 3816*/ 3817SQLITE_API sqlite3 *sqlite3_db_handle(sqlite3_stmt*); 3818 3819/* 3820** CAPI3REF: Find the next prepared statement 3821** 3822** ^This interface returns a pointer to the next [prepared statement] after 3823** pStmt associated with the [database connection] pDb. ^If pStmt is NULL 3824** then this interface returns a pointer to the first prepared statement 3825** associated with the database connection pDb. ^If no prepared statement 3826** satisfies the conditions of this routine, it returns NULL. 3827** 3828** The [database connection] pointer D in a call to 3829** [sqlite3_next_stmt(D,S)] must refer to an open database 3830** connection and in particular must not be a NULL pointer. 3831*/ 3832SQLITE_API sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt); 3833 3834/* 3835** CAPI3REF: Commit And Rollback Notification Callbacks 3836** 3837** ^The sqlite3_commit_hook() interface registers a callback 3838** function to be invoked whenever a transaction is [COMMIT | committed]. 3839** ^Any callback set by a previous call to sqlite3_commit_hook() 3840** for the same database connection is overridden. 3841** ^The sqlite3_rollback_hook() interface registers a callback 3842** function to be invoked whenever a transaction is [ROLLBACK | rolled back]. 3843** ^Any callback set by a previous call to sqlite3_rollback_hook() 3844** for the same database connection is overridden. 3845** ^The pArg argument is passed through to the callback. 3846** ^If the callback on a commit hook function returns non-zero, 3847** then the commit is converted into a rollback. 3848** 3849** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions 3850** return the P argument from the previous call of the same function 3851** on the same [database connection] D, or NULL for 3852** the first call for each function on D. 3853** 3854** The callback implementation must not do anything that will modify 3855** the database connection that invoked the callback. Any actions 3856** to modify the database connection must be deferred until after the 3857** completion of the [sqlite3_step()] call that triggered the commit 3858** or rollback hook in the first place. 3859** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their 3860** database connections for the meaning of "modify" in this paragraph. 3861** 3862** ^Registering a NULL function disables the callback. 3863** 3864** ^When the commit hook callback routine returns zero, the [COMMIT] 3865** operation is allowed to continue normally. ^If the commit hook 3866** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK]. 3867** ^The rollback hook is invoked on a rollback that results from a commit 3868** hook returning non-zero, just as it would be with any other rollback. 3869** 3870** ^For the purposes of this API, a transaction is said to have been 3871** rolled back if an explicit "ROLLBACK" statement is executed, or 3872** an error or constraint causes an implicit rollback to occur. 3873** ^The rollback callback is not invoked if a transaction is 3874** automatically rolled back because the database connection is closed. 3875** ^The rollback callback is not invoked if a transaction is 3876** rolled back because a commit callback returned non-zero. 3877** 3878** See also the [sqlite3_update_hook()] interface. 3879*/ 3880SQLITE_API void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*); 3881SQLITE_API void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*); 3882 3883/* 3884** CAPI3REF: Data Change Notification Callbacks 3885** 3886** ^The sqlite3_update_hook() interface registers a callback function 3887** with the [database connection] identified by the first argument 3888** to be invoked whenever a row is updated, inserted or deleted. 3889** ^Any callback set by a previous call to this function 3890** for the same database connection is overridden. 3891** 3892** ^The second argument is a pointer to the function to invoke when a 3893** row is updated, inserted or deleted. 3894** ^The first argument to the callback is a copy of the third argument 3895** to sqlite3_update_hook(). 3896** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE], 3897** or [SQLITE_UPDATE], depending on the operation that caused the callback 3898** to be invoked. 3899** ^The third and fourth arguments to the callback contain pointers to the 3900** database and table name containing the affected row. 3901** ^The final callback parameter is the [rowid] of the row. 3902** ^In the case of an update, this is the [rowid] after the update takes place. 3903** 3904** ^(The update hook is not invoked when internal system tables are 3905** modified (i.e. sqlite_master and sqlite_sequence).)^ 3906** 3907** ^In the current implementation, the update hook 3908** is not invoked when duplication rows are deleted because of an 3909** [ON CONFLICT | ON CONFLICT REPLACE] clause. ^Nor is the update hook 3910** invoked when rows are deleted using the [truncate optimization]. 3911** The exceptions defined in this paragraph might change in a future 3912** release of SQLite. 3913** 3914** The update hook implementation must not do anything that will modify 3915** the database connection that invoked the update hook. Any actions 3916** to modify the database connection must be deferred until after the 3917** completion of the [sqlite3_step()] call that triggered the update hook. 3918** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their 3919** database connections for the meaning of "modify" in this paragraph. 3920** 3921** ^The sqlite3_update_hook(D,C,P) function 3922** returns the P argument from the previous call 3923** on the same [database connection] D, or NULL for 3924** the first call on D. 3925** 3926** See also the [sqlite3_commit_hook()] and [sqlite3_rollback_hook()] 3927** interfaces. 3928*/ 3929SQLITE_API void *sqlite3_update_hook( 3930 sqlite3*, 3931 void(*)(void *,int ,char const *,char const *,sqlite3_int64), 3932 void* 3933); 3934 3935/* 3936** CAPI3REF: Enable Or Disable Shared Pager Cache 3937** KEYWORDS: {shared cache} 3938** 3939** ^(This routine enables or disables the sharing of the database cache 3940** and schema data structures between [database connection | connections] 3941** to the same database. Sharing is enabled if the argument is true 3942** and disabled if the argument is false.)^ 3943** 3944** ^Cache sharing is enabled and disabled for an entire process. 3945** This is a change as of SQLite version 3.5.0. In prior versions of SQLite, 3946** sharing was enabled or disabled for each thread separately. 3947** 3948** ^(The cache sharing mode set by this interface effects all subsequent 3949** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()]. 3950** Existing database connections continue use the sharing mode 3951** that was in effect at the time they were opened.)^ 3952** 3953** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled 3954** successfully. An [error code] is returned otherwise.)^ 3955** 3956** ^Shared cache is disabled by default. But this might change in 3957** future releases of SQLite. Applications that care about shared 3958** cache setting should set it explicitly. 3959** 3960** See Also: [SQLite Shared-Cache Mode] 3961*/ 3962SQLITE_API int sqlite3_enable_shared_cache(int); 3963 3964/* 3965** CAPI3REF: Attempt To Free Heap Memory 3966** 3967** ^The sqlite3_release_memory() interface attempts to free N bytes 3968** of heap memory by deallocating non-essential memory allocations 3969** held by the database library. Memory used to cache database 3970** pages to improve performance is an example of non-essential memory. 3971** ^sqlite3_release_memory() returns the number of bytes actually freed, 3972** which might be more or less than the amount requested. 3973*/ 3974SQLITE_API int sqlite3_release_memory(int); 3975 3976/* 3977** CAPI3REF: Impose A Limit On Heap Size 3978** 3979** ^The sqlite3_soft_heap_limit() interface places a "soft" limit 3980** on the amount of heap memory that may be allocated by SQLite. 3981** ^If an internal allocation is requested that would exceed the 3982** soft heap limit, [sqlite3_release_memory()] is invoked one or 3983** more times to free up some space before the allocation is performed. 3984** 3985** ^The limit is called "soft" because if [sqlite3_release_memory()] 3986** cannot free sufficient memory to prevent the limit from being exceeded, 3987** the memory is allocated anyway and the current operation proceeds. 3988** 3989** ^A negative or zero value for N means that there is no soft heap limit and 3990** [sqlite3_release_memory()] will only be called when memory is exhausted. 3991** ^The default value for the soft heap limit is zero. 3992** 3993** ^(SQLite makes a best effort to honor the soft heap limit. 3994** But if the soft heap limit cannot be honored, execution will 3995** continue without error or notification.)^ This is why the limit is 3996** called a "soft" limit. It is advisory only. 3997** 3998** Prior to SQLite version 3.5.0, this routine only constrained the memory 3999** allocated by a single thread - the same thread in which this routine 4000** runs. Beginning with SQLite version 3.5.0, the soft heap limit is 4001** applied to all threads. The value specified for the soft heap limit 4002** is an upper bound on the total memory allocation for all threads. In 4003** version 3.5.0 there is no mechanism for limiting the heap usage for 4004** individual threads. 4005*/ 4006SQLITE_API void sqlite3_soft_heap_limit(int); 4007 4008/* 4009** CAPI3REF: Extract Metadata About A Column Of A Table 4010** 4011** ^This routine returns metadata about a specific column of a specific 4012** database table accessible using the [database connection] handle 4013** passed as the first function argument. 4014** 4015** ^The column is identified by the second, third and fourth parameters to 4016** this function. ^The second parameter is either the name of the database 4017** (i.e. "main", "temp", or an attached database) containing the specified 4018** table or NULL. ^If it is NULL, then all attached databases are searched 4019** for the table using the same algorithm used by the database engine to 4020** resolve unqualified table references. 4021** 4022** ^The third and fourth parameters to this function are the table and column 4023** name of the desired column, respectively. Neither of these parameters 4024** may be NULL. 4025** 4026** ^Metadata is returned by writing to the memory locations passed as the 5th 4027** and subsequent parameters to this function. ^Any of these arguments may be 4028** NULL, in which case the corresponding element of metadata is omitted. 4029** 4030** ^(<blockquote> 4031** <table border="1"> 4032** <tr><th> Parameter <th> Output<br>Type <th> Description 4033** 4034** <tr><td> 5th <td> const char* <td> Data type 4035** <tr><td> 6th <td> const char* <td> Name of default collation sequence 4036** <tr><td> 7th <td> int <td> True if column has a NOT NULL constraint 4037** <tr><td> 8th <td> int <td> True if column is part of the PRIMARY KEY 4038** <tr><td> 9th <td> int <td> True if column is [AUTOINCREMENT] 4039** </table> 4040** </blockquote>)^ 4041** 4042** ^The memory pointed to by the character pointers returned for the 4043** declaration type and collation sequence is valid only until the next 4044** call to any SQLite API function. 4045** 4046** ^If the specified table is actually a view, an [error code] is returned. 4047** 4048** ^If the specified column is "rowid", "oid" or "_rowid_" and an 4049** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output 4050** parameters are set for the explicitly declared column. ^(If there is no 4051** explicitly declared [INTEGER PRIMARY KEY] column, then the output 4052** parameters are set as follows: 4053** 4054** <pre> 4055** data type: "INTEGER" 4056** collation sequence: "BINARY" 4057** not null: 0 4058** primary key: 1 4059** auto increment: 0 4060** </pre>)^ 4061** 4062** ^(This function may load one or more schemas from database files. If an 4063** error occurs during this process, or if the requested table or column 4064** cannot be found, an [error code] is returned and an error message left 4065** in the [database connection] (to be retrieved using sqlite3_errmsg()).)^ 4066** 4067** ^This API is only available if the library was compiled with the 4068** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol defined. 4069*/ 4070SQLITE_API int sqlite3_table_column_metadata( 4071 sqlite3 *db, /* Connection handle */ 4072 const char *zDbName, /* Database name or NULL */ 4073 const char *zTableName, /* Table name */ 4074 const char *zColumnName, /* Column name */ 4075 char const **pzDataType, /* OUTPUT: Declared data type */ 4076 char const **pzCollSeq, /* OUTPUT: Collation sequence name */ 4077 int *pNotNull, /* OUTPUT: True if NOT NULL constraint exists */ 4078 int *pPrimaryKey, /* OUTPUT: True if column part of PK */ 4079 int *pAutoinc /* OUTPUT: True if column is auto-increment */ 4080); 4081 4082/* 4083** CAPI3REF: Load An Extension 4084** 4085** ^This interface loads an SQLite extension library from the named file. 4086** 4087** ^The sqlite3_load_extension() interface attempts to load an 4088** SQLite extension library contained in the file zFile. 4089** 4090** ^The entry point is zProc. 4091** ^zProc may be 0, in which case the name of the entry point 4092** defaults to "sqlite3_extension_init". 4093** ^The sqlite3_load_extension() interface returns 4094** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong. 4095** ^If an error occurs and pzErrMsg is not 0, then the 4096** [sqlite3_load_extension()] interface shall attempt to 4097** fill *pzErrMsg with error message text stored in memory 4098** obtained from [sqlite3_malloc()]. The calling function 4099** should free this memory by calling [sqlite3_free()]. 4100** 4101** ^Extension loading must be enabled using 4102** [sqlite3_enable_load_extension()] prior to calling this API, 4103** otherwise an error will be returned. 4104** 4105** See also the [load_extension() SQL function]. 4106*/ 4107SQLITE_API int sqlite3_load_extension( 4108 sqlite3 *db, /* Load the extension into this database connection */ 4109 const char *zFile, /* Name of the shared library containing extension */ 4110 const char *zProc, /* Entry point. Derived from zFile if 0 */ 4111 char **pzErrMsg /* Put error message here if not 0 */ 4112); 4113 4114/* 4115** CAPI3REF: Enable Or Disable Extension Loading 4116** 4117** ^So as not to open security holes in older applications that are 4118** unprepared to deal with extension loading, and as a means of disabling 4119** extension loading while evaluating user-entered SQL, the following API 4120** is provided to turn the [sqlite3_load_extension()] mechanism on and off. 4121** 4122** ^Extension loading is off by default. See ticket #1863. 4123** ^Call the sqlite3_enable_load_extension() routine with onoff==1 4124** to turn extension loading on and call it with onoff==0 to turn 4125** it back off again. 4126*/ 4127SQLITE_API int sqlite3_enable_load_extension(sqlite3 *db, int onoff); 4128 4129/* 4130** CAPI3REF: Automatically Load An Extensions 4131** 4132** ^This API can be invoked at program startup in order to register 4133** one or more statically linked extensions that will be available 4134** to all new [database connections]. 4135** 4136** ^(This routine stores a pointer to the extension entry point 4137** in an array that is obtained from [sqlite3_malloc()]. That memory 4138** is deallocated by [sqlite3_reset_auto_extension()].)^ 4139** 4140** ^This function registers an extension entry point that is 4141** automatically invoked whenever a new [database connection] 4142** is opened using [sqlite3_open()], [sqlite3_open16()], 4143** or [sqlite3_open_v2()]. 4144** ^Duplicate extensions are detected so calling this routine 4145** multiple times with the same extension is harmless. 4146** ^Automatic extensions apply across all threads. 4147*/ 4148SQLITE_API int sqlite3_auto_extension(void (*xEntryPoint)(void)); 4149 4150/* 4151** CAPI3REF: Reset Automatic Extension Loading 4152** 4153** ^(This function disables all previously registered automatic 4154** extensions. It undoes the effect of all prior 4155** [sqlite3_auto_extension()] calls.)^ 4156** 4157** ^This function disables automatic extensions in all threads. 4158*/ 4159SQLITE_API void sqlite3_reset_auto_extension(void); 4160 4161/* 4162****** EXPERIMENTAL - subject to change without notice ************** 4163** 4164** The interface to the virtual-table mechanism is currently considered 4165** to be experimental. The interface might change in incompatible ways. 4166** If this is a problem for you, do not use the interface at this time. 4167** 4168** When the virtual-table mechanism stabilizes, we will declare the 4169** interface fixed, support it indefinitely, and remove this comment. 4170*/ 4171 4172/* 4173** Structures used by the virtual table interface 4174*/ 4175typedef struct sqlite3_vtab sqlite3_vtab; 4176typedef struct sqlite3_index_info sqlite3_index_info; 4177typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor; 4178typedef struct sqlite3_module sqlite3_module; 4179 4180/* 4181** CAPI3REF: Virtual Table Object 4182** KEYWORDS: sqlite3_module {virtual table module} 4183** EXPERIMENTAL 4184** 4185** This structure, sometimes called a a "virtual table module", 4186** defines the implementation of a [virtual tables]. 4187** This structure consists mostly of methods for the module. 4188** 4189** ^A virtual table module is created by filling in a persistent 4190** instance of this structure and passing a pointer to that instance 4191** to [sqlite3_create_module()] or [sqlite3_create_module_v2()]. 4192** ^The registration remains valid until it is replaced by a different 4193** module or until the [database connection] closes. The content 4194** of this structure must not change while it is registered with 4195** any database connection. 4196*/ 4197struct sqlite3_module { 4198 int iVersion; 4199 int (*xCreate)(sqlite3*, void *pAux, 4200 int argc, const char *const*argv, 4201 sqlite3_vtab **ppVTab, char**); 4202 int (*xConnect)(sqlite3*, void *pAux, 4203 int argc, const char *const*argv, 4204 sqlite3_vtab **ppVTab, char**); 4205 int (*xBestIndex)(sqlite3_vtab *pVTab, sqlite3_index_info*); 4206 int (*xDisconnect)(sqlite3_vtab *pVTab); 4207 int (*xDestroy)(sqlite3_vtab *pVTab); 4208 int (*xOpen)(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor); 4209 int (*xClose)(sqlite3_vtab_cursor*); 4210 int (*xFilter)(sqlite3_vtab_cursor*, int idxNum, const char *idxStr, 4211 int argc, sqlite3_value **argv); 4212 int (*xNext)(sqlite3_vtab_cursor*); 4213 int (*xEof)(sqlite3_vtab_cursor*); 4214 int (*xColumn)(sqlite3_vtab_cursor*, sqlite3_context*, int); 4215 int (*xRowid)(sqlite3_vtab_cursor*, sqlite3_int64 *pRowid); 4216 int (*xUpdate)(sqlite3_vtab *, int, sqlite3_value **, sqlite3_int64 *); 4217 int (*xBegin)(sqlite3_vtab *pVTab); 4218 int (*xSync)(sqlite3_vtab *pVTab); 4219 int (*xCommit)(sqlite3_vtab *pVTab); 4220 int (*xRollback)(sqlite3_vtab *pVTab); 4221 int (*xFindFunction)(sqlite3_vtab *pVtab, int nArg, const char *zName, 4222 void (**pxFunc)(sqlite3_context*,int,sqlite3_value**), 4223 void **ppArg); 4224 int (*xRename)(sqlite3_vtab *pVtab, const char *zNew); 4225}; 4226 4227/* 4228** CAPI3REF: Virtual Table Indexing Information 4229** KEYWORDS: sqlite3_index_info 4230** EXPERIMENTAL 4231** 4232** The sqlite3_index_info structure and its substructures is used to 4233** pass information into and receive the reply from the [xBestIndex] 4234** method of a [virtual table module]. The fields under **Inputs** are the 4235** inputs to xBestIndex and are read-only. xBestIndex inserts its 4236** results into the **Outputs** fields. 4237** 4238** ^(The aConstraint[] array records WHERE clause constraints of the form: 4239** 4240** <pre>column OP expr</pre> 4241** 4242** where OP is =, <, <=, >, or >=.)^ ^(The particular operator is 4243** stored in aConstraint[].op.)^ ^(The index of the column is stored in 4244** aConstraint[].iColumn.)^ ^(aConstraint[].usable is TRUE if the 4245** expr on the right-hand side can be evaluated (and thus the constraint 4246** is usable) and false if it cannot.)^ 4247** 4248** ^The optimizer automatically inverts terms of the form "expr OP column" 4249** and makes other simplifications to the WHERE clause in an attempt to 4250** get as many WHERE clause terms into the form shown above as possible. 4251** ^The aConstraint[] array only reports WHERE clause terms that are 4252** relevant to the particular virtual table being queried. 4253** 4254** ^Information about the ORDER BY clause is stored in aOrderBy[]. 4255** ^Each term of aOrderBy records a column of the ORDER BY clause. 4256** 4257** The [xBestIndex] method must fill aConstraintUsage[] with information 4258** about what parameters to pass to xFilter. ^If argvIndex>0 then 4259** the right-hand side of the corresponding aConstraint[] is evaluated 4260** and becomes the argvIndex-th entry in argv. ^(If aConstraintUsage[].omit 4261** is true, then the constraint is assumed to be fully handled by the 4262** virtual table and is not checked again by SQLite.)^ 4263** 4264** ^The idxNum and idxPtr values are recorded and passed into the 4265** [xFilter] method. 4266** ^[sqlite3_free()] is used to free idxPtr if and only if 4267** needToFreeIdxPtr is true. 4268** 4269** ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in 4270** the correct order to satisfy the ORDER BY clause so that no separate 4271** sorting step is required. 4272** 4273** ^The estimatedCost value is an estimate of the cost of doing the 4274** particular lookup. A full scan of a table with N entries should have 4275** a cost of N. A binary search of a table of N entries should have a 4276** cost of approximately log(N). 4277*/ 4278struct sqlite3_index_info { 4279 /* Inputs */ 4280 int nConstraint; /* Number of entries in aConstraint */ 4281 struct sqlite3_index_constraint { 4282 int iColumn; /* Column on left-hand side of constraint */ 4283 unsigned char op; /* Constraint operator */ 4284 unsigned char usable; /* True if this constraint is usable */ 4285 int iTermOffset; /* Used internally - xBestIndex should ignore */ 4286 } *aConstraint; /* Table of WHERE clause constraints */ 4287 int nOrderBy; /* Number of terms in the ORDER BY clause */ 4288 struct sqlite3_index_orderby { 4289 int iColumn; /* Column number */ 4290 unsigned char desc; /* True for DESC. False for ASC. */ 4291 } *aOrderBy; /* The ORDER BY clause */ 4292 /* Outputs */ 4293 struct sqlite3_index_constraint_usage { 4294 int argvIndex; /* if >0, constraint is part of argv to xFilter */ 4295 unsigned char omit; /* Do not code a test for this constraint */ 4296 } *aConstraintUsage; 4297 int idxNum; /* Number used to identify the index */ 4298 char *idxStr; /* String, possibly obtained from sqlite3_malloc */ 4299 int needToFreeIdxStr; /* Free idxStr using sqlite3_free() if true */ 4300 int orderByConsumed; /* True if output is already ordered */ 4301 double estimatedCost; /* Estimated cost of using this index */ 4302}; 4303#define SQLITE_INDEX_CONSTRAINT_EQ 2 4304#define SQLITE_INDEX_CONSTRAINT_GT 4 4305#define SQLITE_INDEX_CONSTRAINT_LE 8 4306#define SQLITE_INDEX_CONSTRAINT_LT 16 4307#define SQLITE_INDEX_CONSTRAINT_GE 32 4308#define SQLITE_INDEX_CONSTRAINT_MATCH 64 4309 4310/* 4311** CAPI3REF: Register A Virtual Table Implementation 4312** EXPERIMENTAL 4313** 4314** ^These routines are used to register a new [virtual table module] name. 4315** ^Module names must be registered before 4316** creating a new [virtual table] using the module and before using a 4317** preexisting [virtual table] for the module. 4318** 4319** ^The module name is registered on the [database connection] specified 4320** by the first parameter. ^The name of the module is given by the 4321** second parameter. ^The third parameter is a pointer to 4322** the implementation of the [virtual table module]. ^The fourth 4323** parameter is an arbitrary client data pointer that is passed through 4324** into the [xCreate] and [xConnect] methods of the virtual table module 4325** when a new virtual table is be being created or reinitialized. 4326** 4327** ^The sqlite3_create_module_v2() interface has a fifth parameter which 4328** is a pointer to a destructor for the pClientData. ^SQLite will 4329** invoke the destructor function (if it is not NULL) when SQLite 4330** no longer needs the pClientData pointer. ^The sqlite3_create_module() 4331** interface is equivalent to sqlite3_create_module_v2() with a NULL 4332** destructor. 4333*/ 4334SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_create_module( 4335 sqlite3 *db, /* SQLite connection to register module with */ 4336 const char *zName, /* Name of the module */ 4337 const sqlite3_module *p, /* Methods for the module */ 4338 void *pClientData /* Client data for xCreate/xConnect */ 4339); 4340SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_create_module_v2( 4341 sqlite3 *db, /* SQLite connection to register module with */ 4342 const char *zName, /* Name of the module */ 4343 const sqlite3_module *p, /* Methods for the module */ 4344 void *pClientData, /* Client data for xCreate/xConnect */ 4345 void(*xDestroy)(void*) /* Module destructor function */ 4346); 4347 4348/* 4349** CAPI3REF: Virtual Table Instance Object 4350** KEYWORDS: sqlite3_vtab 4351** EXPERIMENTAL 4352** 4353** Every [virtual table module] implementation uses a subclass 4354** of this object to describe a particular instance 4355** of the [virtual table]. Each subclass will 4356** be tailored to the specific needs of the module implementation. 4357** The purpose of this superclass is to define certain fields that are 4358** common to all module implementations. 4359** 4360** ^Virtual tables methods can set an error message by assigning a 4361** string obtained from [sqlite3_mprintf()] to zErrMsg. The method should 4362** take care that any prior string is freed by a call to [sqlite3_free()] 4363** prior to assigning a new string to zErrMsg. ^After the error message 4364** is delivered up to the client application, the string will be automatically 4365** freed by sqlite3_free() and the zErrMsg field will be zeroed. 4366*/ 4367struct sqlite3_vtab { 4368 const sqlite3_module *pModule; /* The module for this virtual table */ 4369 int nRef; /* NO LONGER USED */ 4370 char *zErrMsg; /* Error message from sqlite3_mprintf() */ 4371 /* Virtual table implementations will typically add additional fields */ 4372}; 4373 4374/* 4375** CAPI3REF: Virtual Table Cursor Object 4376** KEYWORDS: sqlite3_vtab_cursor {virtual table cursor} 4377** EXPERIMENTAL 4378** 4379** Every [virtual table module] implementation uses a subclass of the 4380** following structure to describe cursors that point into the 4381** [virtual table] and are used 4382** to loop through the virtual table. Cursors are created using the 4383** [sqlite3_module.xOpen | xOpen] method of the module and are destroyed 4384** by the [sqlite3_module.xClose | xClose] method. Cursors are used 4385** by the [xFilter], [xNext], [xEof], [xColumn], and [xRowid] methods 4386** of the module. Each module implementation will define 4387** the content of a cursor structure to suit its own needs. 4388** 4389** This superclass exists in order to define fields of the cursor that 4390** are common to all implementations. 4391*/ 4392struct sqlite3_vtab_cursor { 4393 sqlite3_vtab *pVtab; /* Virtual table of this cursor */ 4394 /* Virtual table implementations will typically add additional fields */ 4395}; 4396 4397/* 4398** CAPI3REF: Declare The Schema Of A Virtual Table 4399** EXPERIMENTAL 4400** 4401** ^The [xCreate] and [xConnect] methods of a 4402** [virtual table module] call this interface 4403** to declare the format (the names and datatypes of the columns) of 4404** the virtual tables they implement. 4405*/ 4406SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_declare_vtab(sqlite3*, const char *zSQL); 4407 4408/* 4409** CAPI3REF: Overload A Function For A Virtual Table 4410** EXPERIMENTAL 4411** 4412** ^(Virtual tables can provide alternative implementations of functions 4413** using the [xFindFunction] method of the [virtual table module]. 4414** But global versions of those functions 4415** must exist in order to be overloaded.)^ 4416** 4417** ^(This API makes sure a global version of a function with a particular 4418** name and number of parameters exists. If no such function exists 4419** before this API is called, a new function is created.)^ ^The implementation 4420** of the new function always causes an exception to be thrown. So 4421** the new function is not good for anything by itself. Its only 4422** purpose is to be a placeholder function that can be overloaded 4423** by a [virtual table]. 4424*/ 4425SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg); 4426 4427/* 4428** The interface to the virtual-table mechanism defined above (back up 4429** to a comment remarkably similar to this one) is currently considered 4430** to be experimental. The interface might change in incompatible ways. 4431** If this is a problem for you, do not use the interface at this time. 4432** 4433** When the virtual-table mechanism stabilizes, we will declare the 4434** interface fixed, support it indefinitely, and remove this comment. 4435** 4436****** EXPERIMENTAL - subject to change without notice ************** 4437*/ 4438 4439/* 4440** CAPI3REF: A Handle To An Open BLOB 4441** KEYWORDS: {BLOB handle} {BLOB handles} 4442** 4443** An instance of this object represents an open BLOB on which 4444** [sqlite3_blob_open | incremental BLOB I/O] can be performed. 4445** ^Objects of this type are created by [sqlite3_blob_open()] 4446** and destroyed by [sqlite3_blob_close()]. 4447** ^The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces 4448** can be used to read or write small subsections of the BLOB. 4449** ^The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes. 4450*/ 4451typedef struct sqlite3_blob sqlite3_blob; 4452 4453/* 4454** CAPI3REF: Open A BLOB For Incremental I/O 4455** 4456** ^(This interfaces opens a [BLOB handle | handle] to the BLOB located 4457** in row iRow, column zColumn, table zTable in database zDb; 4458** in other words, the same BLOB that would be selected by: 4459** 4460** <pre> 4461** SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow; 4462** </pre>)^ 4463** 4464** ^If the flags parameter is non-zero, then the BLOB is opened for read 4465** and write access. ^If it is zero, the BLOB is opened for read access. 4466** ^It is not possible to open a column that is part of an index or primary 4467** key for writing. ^If [foreign key constraints] are enabled, it is 4468** not possible to open a column that is part of a [child key] for writing. 4469** 4470** ^Note that the database name is not the filename that contains 4471** the database but rather the symbolic name of the database that 4472** appears after the AS keyword when the database is connected using [ATTACH]. 4473** ^For the main database file, the database name is "main". 4474** ^For TEMP tables, the database name is "temp". 4475** 4476** ^(On success, [SQLITE_OK] is returned and the new [BLOB handle] is written 4477** to *ppBlob. Otherwise an [error code] is returned and *ppBlob is set 4478** to be a null pointer.)^ 4479** ^This function sets the [database connection] error code and message 4480** accessible via [sqlite3_errcode()] and [sqlite3_errmsg()] and related 4481** functions. ^Note that the *ppBlob variable is always initialized in a 4482** way that makes it safe to invoke [sqlite3_blob_close()] on *ppBlob 4483** regardless of the success or failure of this routine. 4484** 4485** ^(If the row that a BLOB handle points to is modified by an 4486** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects 4487** then the BLOB handle is marked as "expired". 4488** This is true if any column of the row is changed, even a column 4489** other than the one the BLOB handle is open on.)^ 4490** ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for 4491** a expired BLOB handle fail with an return code of [SQLITE_ABORT]. 4492** ^(Changes written into a BLOB prior to the BLOB expiring are not 4493** rolled back by the expiration of the BLOB. Such changes will eventually 4494** commit if the transaction continues to completion.)^ 4495** 4496** ^Use the [sqlite3_blob_bytes()] interface to determine the size of 4497** the opened blob. ^The size of a blob may not be changed by this 4498** interface. Use the [UPDATE] SQL command to change the size of a 4499** blob. 4500** 4501** ^The [sqlite3_bind_zeroblob()] and [sqlite3_result_zeroblob()] interfaces 4502** and the built-in [zeroblob] SQL function can be used, if desired, 4503** to create an empty, zero-filled blob in which to read or write using 4504** this interface. 4505** 4506** To avoid a resource leak, every open [BLOB handle] should eventually 4507** be released by a call to [sqlite3_blob_close()]. 4508*/ 4509SQLITE_API int sqlite3_blob_open( 4510 sqlite3*, 4511 const char *zDb, 4512 const char *zTable, 4513 const char *zColumn, 4514 sqlite3_int64 iRow, 4515 int flags, 4516 sqlite3_blob **ppBlob 4517); 4518 4519/* 4520** CAPI3REF: Close A BLOB Handle 4521** 4522** ^Closes an open [BLOB handle]. 4523** 4524** ^Closing a BLOB shall cause the current transaction to commit 4525** if there are no other BLOBs, no pending prepared statements, and the 4526** database connection is in [autocommit mode]. 4527** ^If any writes were made to the BLOB, they might be held in cache 4528** until the close operation if they will fit. 4529** 4530** ^(Closing the BLOB often forces the changes 4531** out to disk and so if any I/O errors occur, they will likely occur 4532** at the time when the BLOB is closed. Any errors that occur during 4533** closing are reported as a non-zero return value.)^ 4534** 4535** ^(The BLOB is closed unconditionally. Even if this routine returns 4536** an error code, the BLOB is still closed.)^ 4537** 4538** ^Calling this routine with a null pointer (such as would be returned 4539** by a failed call to [sqlite3_blob_open()]) is a harmless no-op. 4540*/ 4541SQLITE_API int sqlite3_blob_close(sqlite3_blob *); 4542 4543/* 4544** CAPI3REF: Return The Size Of An Open BLOB 4545** 4546** ^Returns the size in bytes of the BLOB accessible via the 4547** successfully opened [BLOB handle] in its only argument. ^The 4548** incremental blob I/O routines can only read or overwriting existing 4549** blob content; they cannot change the size of a blob. 4550** 4551** This routine only works on a [BLOB handle] which has been created 4552** by a prior successful call to [sqlite3_blob_open()] and which has not 4553** been closed by [sqlite3_blob_close()]. Passing any other pointer in 4554** to this routine results in undefined and probably undesirable behavior. 4555*/ 4556SQLITE_API int sqlite3_blob_bytes(sqlite3_blob *); 4557 4558/* 4559** CAPI3REF: Read Data From A BLOB Incrementally 4560** 4561** ^(This function is used to read data from an open [BLOB handle] into a 4562** caller-supplied buffer. N bytes of data are copied into buffer Z 4563** from the open BLOB, starting at offset iOffset.)^ 4564** 4565** ^If offset iOffset is less than N bytes from the end of the BLOB, 4566** [SQLITE_ERROR] is returned and no data is read. ^If N or iOffset is 4567** less than zero, [SQLITE_ERROR] is returned and no data is read. 4568** ^The size of the blob (and hence the maximum value of N+iOffset) 4569** can be determined using the [sqlite3_blob_bytes()] interface. 4570** 4571** ^An attempt to read from an expired [BLOB handle] fails with an 4572** error code of [SQLITE_ABORT]. 4573** 4574** ^(On success, sqlite3_blob_read() returns SQLITE_OK. 4575** Otherwise, an [error code] or an [extended error code] is returned.)^ 4576** 4577** This routine only works on a [BLOB handle] which has been created 4578** by a prior successful call to [sqlite3_blob_open()] and which has not 4579** been closed by [sqlite3_blob_close()]. Passing any other pointer in 4580** to this routine results in undefined and probably undesirable behavior. 4581** 4582** See also: [sqlite3_blob_write()]. 4583*/ 4584SQLITE_API int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset); 4585 4586/* 4587** CAPI3REF: Write Data Into A BLOB Incrementally 4588** 4589** ^This function is used to write data into an open [BLOB handle] from a 4590** caller-supplied buffer. ^N bytes of data are copied from the buffer Z 4591** into the open BLOB, starting at offset iOffset. 4592** 4593** ^If the [BLOB handle] passed as the first argument was not opened for 4594** writing (the flags parameter to [sqlite3_blob_open()] was zero), 4595** this function returns [SQLITE_READONLY]. 4596** 4597** ^This function may only modify the contents of the BLOB; it is 4598** not possible to increase the size of a BLOB using this API. 4599** ^If offset iOffset is less than N bytes from the end of the BLOB, 4600** [SQLITE_ERROR] is returned and no data is written. ^If N is 4601** less than zero [SQLITE_ERROR] is returned and no data is written. 4602** The size of the BLOB (and hence the maximum value of N+iOffset) 4603** can be determined using the [sqlite3_blob_bytes()] interface. 4604** 4605** ^An attempt to write to an expired [BLOB handle] fails with an 4606** error code of [SQLITE_ABORT]. ^Writes to the BLOB that occurred 4607** before the [BLOB handle] expired are not rolled back by the 4608** expiration of the handle, though of course those changes might 4609** have been overwritten by the statement that expired the BLOB handle 4610** or by other independent statements. 4611** 4612** ^(On success, sqlite3_blob_write() returns SQLITE_OK. 4613** Otherwise, an [error code] or an [extended error code] is returned.)^ 4614** 4615** This routine only works on a [BLOB handle] which has been created 4616** by a prior successful call to [sqlite3_blob_open()] and which has not 4617** been closed by [sqlite3_blob_close()]. Passing any other pointer in 4618** to this routine results in undefined and probably undesirable behavior. 4619** 4620** See also: [sqlite3_blob_read()]. 4621*/ 4622SQLITE_API int sqlite3_blob_write(sqlite3_blob *, const void *z, int n, int iOffset); 4623 4624/* 4625** CAPI3REF: Virtual File System Objects 4626** 4627** A virtual filesystem (VFS) is an [sqlite3_vfs] object 4628** that SQLite uses to interact 4629** with the underlying operating system. Most SQLite builds come with a 4630** single default VFS that is appropriate for the host computer. 4631** New VFSes can be registered and existing VFSes can be unregistered. 4632** The following interfaces are provided. 4633** 4634** ^The sqlite3_vfs_find() interface returns a pointer to a VFS given its name. 4635** ^Names are case sensitive. 4636** ^Names are zero-terminated UTF-8 strings. 4637** ^If there is no match, a NULL pointer is returned. 4638** ^If zVfsName is NULL then the default VFS is returned. 4639** 4640** ^New VFSes are registered with sqlite3_vfs_register(). 4641** ^Each new VFS becomes the default VFS if the makeDflt flag is set. 4642** ^The same VFS can be registered multiple times without injury. 4643** ^To make an existing VFS into the default VFS, register it again 4644** with the makeDflt flag set. If two different VFSes with the 4645** same name are registered, the behavior is undefined. If a 4646** VFS is registered with a name that is NULL or an empty string, 4647** then the behavior is undefined. 4648** 4649** ^Unregister a VFS with the sqlite3_vfs_unregister() interface. 4650** ^(If the default VFS is unregistered, another VFS is chosen as 4651** the default. The choice for the new VFS is arbitrary.)^ 4652*/ 4653SQLITE_API sqlite3_vfs *sqlite3_vfs_find(const char *zVfsName); 4654SQLITE_API int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt); 4655SQLITE_API int sqlite3_vfs_unregister(sqlite3_vfs*); 4656 4657/* 4658** CAPI3REF: Mutexes 4659** 4660** The SQLite core uses these routines for thread 4661** synchronization. Though they are intended for internal 4662** use by SQLite, code that links against SQLite is 4663** permitted to use any of these routines. 4664** 4665** The SQLite source code contains multiple implementations 4666** of these mutex routines. An appropriate implementation 4667** is selected automatically at compile-time. ^(The following 4668** implementations are available in the SQLite core: 4669** 4670** <ul> 4671** <li> SQLITE_MUTEX_OS2 4672** <li> SQLITE_MUTEX_PTHREAD 4673** <li> SQLITE_MUTEX_W32 4674** <li> SQLITE_MUTEX_NOOP 4675** </ul>)^ 4676** 4677** ^The SQLITE_MUTEX_NOOP implementation is a set of routines 4678** that does no real locking and is appropriate for use in 4679** a single-threaded application. ^The SQLITE_MUTEX_OS2, 4680** SQLITE_MUTEX_PTHREAD, and SQLITE_MUTEX_W32 implementations 4681** are appropriate for use on OS/2, Unix, and Windows. 4682** 4683** ^(If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor 4684** macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex 4685** implementation is included with the library. In this case the 4686** application must supply a custom mutex implementation using the 4687** [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function 4688** before calling sqlite3_initialize() or any other public sqlite3_ 4689** function that calls sqlite3_initialize().)^ 4690** 4691** ^The sqlite3_mutex_alloc() routine allocates a new 4692** mutex and returns a pointer to it. ^If it returns NULL 4693** that means that a mutex could not be allocated. ^SQLite 4694** will unwind its stack and return an error. ^(The argument 4695** to sqlite3_mutex_alloc() is one of these integer constants: 4696** 4697** <ul> 4698** <li> SQLITE_MUTEX_FAST 4699** <li> SQLITE_MUTEX_RECURSIVE 4700** <li> SQLITE_MUTEX_STATIC_MASTER 4701** <li> SQLITE_MUTEX_STATIC_MEM 4702** <li> SQLITE_MUTEX_STATIC_MEM2 4703** <li> SQLITE_MUTEX_STATIC_PRNG 4704** <li> SQLITE_MUTEX_STATIC_LRU 4705** <li> SQLITE_MUTEX_STATIC_LRU2 4706** </ul>)^ 4707** 4708** ^The first two constants (SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE) 4709** cause sqlite3_mutex_alloc() to create 4710** a new mutex. ^The new mutex is recursive when SQLITE_MUTEX_RECURSIVE 4711** is used but not necessarily so when SQLITE_MUTEX_FAST is used. 4712** The mutex implementation does not need to make a distinction 4713** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does 4714** not want to. ^SQLite will only request a recursive mutex in 4715** cases where it really needs one. ^If a faster non-recursive mutex 4716** implementation is available on the host platform, the mutex subsystem 4717** might return such a mutex in response to SQLITE_MUTEX_FAST. 4718** 4719** ^The other allowed parameters to sqlite3_mutex_alloc() (anything other 4720** than SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE) each return 4721** a pointer to a static preexisting mutex. ^Six static mutexes are 4722** used by the current version of SQLite. Future versions of SQLite 4723** may add additional static mutexes. Static mutexes are for internal 4724** use by SQLite only. Applications that use SQLite mutexes should 4725** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or 4726** SQLITE_MUTEX_RECURSIVE. 4727** 4728** ^Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST 4729** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc() 4730** returns a different mutex on every call. ^But for the static 4731** mutex types, the same mutex is returned on every call that has 4732** the same type number. 4733** 4734** ^The sqlite3_mutex_free() routine deallocates a previously 4735** allocated dynamic mutex. ^SQLite is careful to deallocate every 4736** dynamic mutex that it allocates. The dynamic mutexes must not be in 4737** use when they are deallocated. Attempting to deallocate a static 4738** mutex results in undefined behavior. ^SQLite never deallocates 4739** a static mutex. 4740** 4741** ^The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt 4742** to enter a mutex. ^If another thread is already within the mutex, 4743** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return 4744** SQLITE_BUSY. ^The sqlite3_mutex_try() interface returns [SQLITE_OK] 4745** upon successful entry. ^(Mutexes created using 4746** SQLITE_MUTEX_RECURSIVE can be entered multiple times by the same thread. 4747** In such cases the, 4748** mutex must be exited an equal number of times before another thread 4749** can enter.)^ ^(If the same thread tries to enter any other 4750** kind of mutex more than once, the behavior is undefined. 4751** SQLite will never exhibit 4752** such behavior in its own use of mutexes.)^ 4753** 4754** ^(Some systems (for example, Windows 95) do not support the operation 4755** implemented by sqlite3_mutex_try(). On those systems, sqlite3_mutex_try() 4756** will always return SQLITE_BUSY. The SQLite core only ever uses 4757** sqlite3_mutex_try() as an optimization so this is acceptable behavior.)^ 4758** 4759** ^The sqlite3_mutex_leave() routine exits a mutex that was 4760** previously entered by the same thread. ^(The behavior 4761** is undefined if the mutex is not currently entered by the 4762** calling thread or is not currently allocated. SQLite will 4763** never do either.)^ 4764** 4765** ^If the argument to sqlite3_mutex_enter(), sqlite3_mutex_try(), or 4766** sqlite3_mutex_leave() is a NULL pointer, then all three routines 4767** behave as no-ops. 4768** 4769** See also: [sqlite3_mutex_held()] and [sqlite3_mutex_notheld()]. 4770*/ 4771SQLITE_API sqlite3_mutex *sqlite3_mutex_alloc(int); 4772SQLITE_API void sqlite3_mutex_free(sqlite3_mutex*); 4773SQLITE_API void sqlite3_mutex_enter(sqlite3_mutex*); 4774SQLITE_API int sqlite3_mutex_try(sqlite3_mutex*); 4775SQLITE_API void sqlite3_mutex_leave(sqlite3_mutex*); 4776 4777/* 4778** CAPI3REF: Mutex Methods Object 4779** EXPERIMENTAL 4780** 4781** An instance of this structure defines the low-level routines 4782** used to allocate and use mutexes. 4783** 4784** Usually, the default mutex implementations provided by SQLite are 4785** sufficient, however the user has the option of substituting a custom 4786** implementation for specialized deployments or systems for which SQLite 4787** does not provide a suitable implementation. In this case, the user 4788** creates and populates an instance of this structure to pass 4789** to sqlite3_config() along with the [SQLITE_CONFIG_MUTEX] option. 4790** Additionally, an instance of this structure can be used as an 4791** output variable when querying the system for the current mutex 4792** implementation, using the [SQLITE_CONFIG_GETMUTEX] option. 4793** 4794** ^The xMutexInit method defined by this structure is invoked as 4795** part of system initialization by the sqlite3_initialize() function. 4796** ^The xMutexInit routine is calle by SQLite exactly once for each 4797** effective call to [sqlite3_initialize()]. 4798** 4799** ^The xMutexEnd method defined by this structure is invoked as 4800** part of system shutdown by the sqlite3_shutdown() function. The 4801** implementation of this method is expected to release all outstanding 4802** resources obtained by the mutex methods implementation, especially 4803** those obtained by the xMutexInit method. ^The xMutexEnd() 4804** interface is invoked exactly once for each call to [sqlite3_shutdown()]. 4805** 4806** ^(The remaining seven methods defined by this structure (xMutexAlloc, 4807** xMutexFree, xMutexEnter, xMutexTry, xMutexLeave, xMutexHeld and 4808** xMutexNotheld) implement the following interfaces (respectively): 4809** 4810** <ul> 4811** <li> [sqlite3_mutex_alloc()] </li> 4812** <li> [sqlite3_mutex_free()] </li> 4813** <li> [sqlite3_mutex_enter()] </li> 4814** <li> [sqlite3_mutex_try()] </li> 4815** <li> [sqlite3_mutex_leave()] </li> 4816** <li> [sqlite3_mutex_held()] </li> 4817** <li> [sqlite3_mutex_notheld()] </li> 4818** </ul>)^ 4819** 4820** The only difference is that the public sqlite3_XXX functions enumerated 4821** above silently ignore any invocations that pass a NULL pointer instead 4822** of a valid mutex handle. The implementations of the methods defined 4823** by this structure are not required to handle this case, the results 4824** of passing a NULL pointer instead of a valid mutex handle are undefined 4825** (i.e. it is acceptable to provide an implementation that segfaults if 4826** it is passed a NULL pointer). 4827** 4828** The xMutexInit() method must be threadsafe. ^It must be harmless to 4829** invoke xMutexInit() mutiple times within the same process and without 4830** intervening calls to xMutexEnd(). Second and subsequent calls to 4831** xMutexInit() must be no-ops. 4832** 4833** ^xMutexInit() must not use SQLite memory allocation ([sqlite3_malloc()] 4834** and its associates). ^Similarly, xMutexAlloc() must not use SQLite memory 4835** allocation for a static mutex. ^However xMutexAlloc() may use SQLite 4836** memory allocation for a fast or recursive mutex. 4837** 4838** ^SQLite will invoke the xMutexEnd() method when [sqlite3_shutdown()] is 4839** called, but only if the prior call to xMutexInit returned SQLITE_OK. 4840** If xMutexInit fails in any way, it is expected to clean up after itself 4841** prior to returning. 4842*/ 4843typedef struct sqlite3_mutex_methods sqlite3_mutex_methods; 4844struct sqlite3_mutex_methods { 4845 int (*xMutexInit)(void); 4846 int (*xMutexEnd)(void); 4847 sqlite3_mutex *(*xMutexAlloc)(int); 4848 void (*xMutexFree)(sqlite3_mutex *); 4849 void (*xMutexEnter)(sqlite3_mutex *); 4850 int (*xMutexTry)(sqlite3_mutex *); 4851 void (*xMutexLeave)(sqlite3_mutex *); 4852 int (*xMutexHeld)(sqlite3_mutex *); 4853 int (*xMutexNotheld)(sqlite3_mutex *); 4854}; 4855 4856/* 4857** CAPI3REF: Mutex Verification Routines 4858** 4859** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routines 4860** are intended for use inside assert() statements. ^The SQLite core 4861** never uses these routines except inside an assert() and applications 4862** are advised to follow the lead of the core. ^The SQLite core only 4863** provides implementations for these routines when it is compiled 4864** with the SQLITE_DEBUG flag. ^External mutex implementations 4865** are only required to provide these routines if SQLITE_DEBUG is 4866** defined and if NDEBUG is not defined. 4867** 4868** ^These routines should return true if the mutex in their argument 4869** is held or not held, respectively, by the calling thread. 4870** 4871** ^The implementation is not required to provided versions of these 4872** routines that actually work. If the implementation does not provide working 4873** versions of these routines, it should at least provide stubs that always 4874** return true so that one does not get spurious assertion failures. 4875** 4876** ^If the argument to sqlite3_mutex_held() is a NULL pointer then 4877** the routine should return 1. This seems counter-intuitive since 4878** clearly the mutex cannot be held if it does not exist. But the 4879** the reason the mutex does not exist is because the build is not 4880** using mutexes. And we do not want the assert() containing the 4881** call to sqlite3_mutex_held() to fail, so a non-zero return is 4882** the appropriate thing to do. ^The sqlite3_mutex_notheld() 4883** interface should also return 1 when given a NULL pointer. 4884*/ 4885#ifndef NDEBUG 4886SQLITE_API int sqlite3_mutex_held(sqlite3_mutex*); 4887SQLITE_API int sqlite3_mutex_notheld(sqlite3_mutex*); 4888#endif 4889 4890/* 4891** CAPI3REF: Mutex Types 4892** 4893** The [sqlite3_mutex_alloc()] interface takes a single argument 4894** which is one of these integer constants. 4895** 4896** The set of static mutexes may change from one SQLite release to the 4897** next. Applications that override the built-in mutex logic must be 4898** prepared to accommodate additional static mutexes. 4899*/ 4900#define SQLITE_MUTEX_FAST 0 4901#define SQLITE_MUTEX_RECURSIVE 1 4902#define SQLITE_MUTEX_STATIC_MASTER 2 4903#define SQLITE_MUTEX_STATIC_MEM 3 /* sqlite3_malloc() */ 4904#define SQLITE_MUTEX_STATIC_MEM2 4 /* NOT USED */ 4905#define SQLITE_MUTEX_STATIC_OPEN 4 /* sqlite3BtreeOpen() */ 4906#define SQLITE_MUTEX_STATIC_PRNG 5 /* sqlite3_random() */ 4907#define SQLITE_MUTEX_STATIC_LRU 6 /* lru page list */ 4908#define SQLITE_MUTEX_STATIC_LRU2 7 /* lru page list */ 4909 4910/* 4911** CAPI3REF: Retrieve the mutex for a database connection 4912** 4913** ^This interface returns a pointer the [sqlite3_mutex] object that 4914** serializes access to the [database connection] given in the argument 4915** when the [threading mode] is Serialized. 4916** ^If the [threading mode] is Single-thread or Multi-thread then this 4917** routine returns a NULL pointer. 4918*/ 4919SQLITE_API sqlite3_mutex *sqlite3_db_mutex(sqlite3*); 4920 4921/* 4922** CAPI3REF: Low-Level Control Of Database Files 4923** 4924** ^The [sqlite3_file_control()] interface makes a direct call to the 4925** xFileControl method for the [sqlite3_io_methods] object associated 4926** with a particular database identified by the second argument. ^The 4927** name of the database "main" for the main database or "temp" for the 4928** TEMP database, or the name that appears after the AS keyword for 4929** databases that are added using the [ATTACH] SQL command. 4930** ^A NULL pointer can be used in place of "main" to refer to the 4931** main database file. 4932** ^The third and fourth parameters to this routine 4933** are passed directly through to the second and third parameters of 4934** the xFileControl method. ^The return value of the xFileControl 4935** method becomes the return value of this routine. 4936** 4937** ^If the second parameter (zDbName) does not match the name of any 4938** open database file, then SQLITE_ERROR is returned. ^This error 4939** code is not remembered and will not be recalled by [sqlite3_errcode()] 4940** or [sqlite3_errmsg()]. The underlying xFileControl method might 4941** also return SQLITE_ERROR. There is no way to distinguish between 4942** an incorrect zDbName and an SQLITE_ERROR return from the underlying 4943** xFileControl method. 4944** 4945** See also: [SQLITE_FCNTL_LOCKSTATE] 4946*/ 4947SQLITE_API int sqlite3_file_control(sqlite3*, const char *zDbName, int op, void*); 4948 4949/* 4950** CAPI3REF: Testing Interface 4951** 4952** ^The sqlite3_test_control() interface is used to read out internal 4953** state of SQLite and to inject faults into SQLite for testing 4954** purposes. ^The first parameter is an operation code that determines 4955** the number, meaning, and operation of all subsequent parameters. 4956** 4957** This interface is not for use by applications. It exists solely 4958** for verifying the correct operation of the SQLite library. Depending 4959** on how the SQLite library is compiled, this interface might not exist. 4960** 4961** The details of the operation codes, their meanings, the parameters 4962** they take, and what they do are all subject to change without notice. 4963** Unlike most of the SQLite API, this function is not guaranteed to 4964** operate consistently from one release to the next. 4965*/ 4966SQLITE_API int sqlite3_test_control(int op, ...); 4967 4968/* 4969** CAPI3REF: Testing Interface Operation Codes 4970** 4971** These constants are the valid operation code parameters used 4972** as the first argument to [sqlite3_test_control()]. 4973** 4974** These parameters and their meanings are subject to change 4975** without notice. These values are for testing purposes only. 4976** Applications should not use any of these parameters or the 4977** [sqlite3_test_control()] interface. 4978*/ 4979#define SQLITE_TESTCTRL_FIRST 5 4980#define SQLITE_TESTCTRL_PRNG_SAVE 5 4981#define SQLITE_TESTCTRL_PRNG_RESTORE 6 4982#define SQLITE_TESTCTRL_PRNG_RESET 7 4983#define SQLITE_TESTCTRL_BITVEC_TEST 8 4984#define SQLITE_TESTCTRL_FAULT_INSTALL 9 4985#define SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS 10 4986#define SQLITE_TESTCTRL_PENDING_BYTE 11 4987#define SQLITE_TESTCTRL_ASSERT 12 4988#define SQLITE_TESTCTRL_ALWAYS 13 4989#define SQLITE_TESTCTRL_RESERVE 14 4990#define SQLITE_TESTCTRL_OPTIMIZATIONS 15 4991#define SQLITE_TESTCTRL_ISKEYWORD 16 4992#define SQLITE_TESTCTRL_LAST 16 4993 4994/* 4995** CAPI3REF: SQLite Runtime Status 4996** EXPERIMENTAL 4997** 4998** ^This interface is used to retrieve runtime status information 4999** about the preformance of SQLite, and optionally to reset various 5000** highwater marks. ^The first argument is an integer code for 5001** the specific parameter to measure. ^(Recognized integer codes 5002** are of the form [SQLITE_STATUS_MEMORY_USED | SQLITE_STATUS_...].)^ 5003** ^The current value of the parameter is returned into *pCurrent. 5004** ^The highest recorded value is returned in *pHighwater. ^If the 5005** resetFlag is true, then the highest record value is reset after 5006** *pHighwater is written. ^(Some parameters do not record the highest 5007** value. For those parameters 5008** nothing is written into *pHighwater and the resetFlag is ignored.)^ 5009** ^(Other parameters record only the highwater mark and not the current 5010** value. For these latter parameters nothing is written into *pCurrent.)^ 5011** 5012** ^The sqlite3_db_status() routine returns SQLITE_OK on success and a 5013** non-zero [error code] on failure. 5014** 5015** This routine is threadsafe but is not atomic. This routine can be 5016** called while other threads are running the same or different SQLite 5017** interfaces. However the values returned in *pCurrent and 5018** *pHighwater reflect the status of SQLite at different points in time 5019** and it is possible that another thread might change the parameter 5020** in between the times when *pCurrent and *pHighwater are written. 5021** 5022** See also: [sqlite3_db_status()] 5023*/ 5024SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag); 5025 5026 5027/* 5028** CAPI3REF: Status Parameters 5029** EXPERIMENTAL 5030** 5031** These integer constants designate various run-time status parameters 5032** that can be returned by [sqlite3_status()]. 5033** 5034** <dl> 5035** ^(<dt>SQLITE_STATUS_MEMORY_USED</dt> 5036** <dd>This parameter is the current amount of memory checked out 5037** using [sqlite3_malloc()], either directly or indirectly. The 5038** figure includes calls made to [sqlite3_malloc()] by the application 5039** and internal memory usage by the SQLite library. Scratch memory 5040** controlled by [SQLITE_CONFIG_SCRATCH] and auxiliary page-cache 5041** memory controlled by [SQLITE_CONFIG_PAGECACHE] is not included in 5042** this parameter. The amount returned is the sum of the allocation 5043** sizes as reported by the xSize method in [sqlite3_mem_methods].</dd>)^ 5044** 5045** ^(<dt>SQLITE_STATUS_MALLOC_SIZE</dt> 5046** <dd>This parameter records the largest memory allocation request 5047** handed to [sqlite3_malloc()] or [sqlite3_realloc()] (or their 5048** internal equivalents). Only the value returned in the 5049** *pHighwater parameter to [sqlite3_status()] is of interest. 5050** The value written into the *pCurrent parameter is undefined.</dd>)^ 5051** 5052** ^(<dt>SQLITE_STATUS_PAGECACHE_USED</dt> 5053** <dd>This parameter returns the number of pages used out of the 5054** [pagecache memory allocator] that was configured using 5055** [SQLITE_CONFIG_PAGECACHE]. The 5056** value returned is in pages, not in bytes.</dd>)^ 5057** 5058** ^(<dt>SQLITE_STATUS_PAGECACHE_OVERFLOW</dt> 5059** <dd>This parameter returns the number of bytes of page cache 5060** allocation which could not be statisfied by the [SQLITE_CONFIG_PAGECACHE] 5061** buffer and where forced to overflow to [sqlite3_malloc()]. The 5062** returned value includes allocations that overflowed because they 5063** where too large (they were larger than the "sz" parameter to 5064** [SQLITE_CONFIG_PAGECACHE]) and allocations that overflowed because 5065** no space was left in the page cache.</dd>)^ 5066** 5067** ^(<dt>SQLITE_STATUS_PAGECACHE_SIZE</dt> 5068** <dd>This parameter records the largest memory allocation request 5069** handed to [pagecache memory allocator]. Only the value returned in the 5070** *pHighwater parameter to [sqlite3_status()] is of interest. 5071** The value written into the *pCurrent parameter is undefined.</dd>)^ 5072** 5073** ^(<dt>SQLITE_STATUS_SCRATCH_USED</dt> 5074** <dd>This parameter returns the number of allocations used out of the 5075** [scratch memory allocator] configured using 5076** [SQLITE_CONFIG_SCRATCH]. The value returned is in allocations, not 5077** in bytes. Since a single thread may only have one scratch allocation 5078** outstanding at time, this parameter also reports the number of threads 5079** using scratch memory at the same time.</dd>)^ 5080** 5081** ^(<dt>SQLITE_STATUS_SCRATCH_OVERFLOW</dt> 5082** <dd>This parameter returns the number of bytes of scratch memory 5083** allocation which could not be statisfied by the [SQLITE_CONFIG_SCRATCH] 5084** buffer and where forced to overflow to [sqlite3_malloc()]. The values 5085** returned include overflows because the requested allocation was too 5086** larger (that is, because the requested allocation was larger than the 5087** "sz" parameter to [SQLITE_CONFIG_SCRATCH]) and because no scratch buffer 5088** slots were available. 5089** </dd>)^ 5090** 5091** ^(<dt>SQLITE_STATUS_SCRATCH_SIZE</dt> 5092** <dd>This parameter records the largest memory allocation request 5093** handed to [scratch memory allocator]. Only the value returned in the 5094** *pHighwater parameter to [sqlite3_status()] is of interest. 5095** The value written into the *pCurrent parameter is undefined.</dd>)^ 5096** 5097** ^(<dt>SQLITE_STATUS_PARSER_STACK</dt> 5098** <dd>This parameter records the deepest parser stack. It is only 5099** meaningful if SQLite is compiled with [YYTRACKMAXSTACKDEPTH].</dd>)^ 5100** </dl> 5101** 5102** New status parameters may be added from time to time. 5103*/ 5104#define SQLITE_STATUS_MEMORY_USED 0 5105#define SQLITE_STATUS_PAGECACHE_USED 1 5106#define SQLITE_STATUS_PAGECACHE_OVERFLOW 2 5107#define SQLITE_STATUS_SCRATCH_USED 3 5108#define SQLITE_STATUS_SCRATCH_OVERFLOW 4 5109#define SQLITE_STATUS_MALLOC_SIZE 5 5110#define SQLITE_STATUS_PARSER_STACK 6 5111#define SQLITE_STATUS_PAGECACHE_SIZE 7 5112#define SQLITE_STATUS_SCRATCH_SIZE 8 5113 5114/* 5115** CAPI3REF: Database Connection Status 5116** EXPERIMENTAL 5117** 5118** ^This interface is used to retrieve runtime status information 5119** about a single [database connection]. ^The first argument is the 5120** database connection object to be interrogated. ^The second argument 5121** is the parameter to interrogate. ^Currently, the only allowed value 5122** for the second parameter is [SQLITE_DBSTATUS_LOOKASIDE_USED]. 5123** Additional options will likely appear in future releases of SQLite. 5124** 5125** ^The current value of the requested parameter is written into *pCur 5126** and the highest instantaneous value is written into *pHiwtr. ^If 5127** the resetFlg is true, then the highest instantaneous value is 5128** reset back down to the current value. 5129** 5130** See also: [sqlite3_status()] and [sqlite3_stmt_status()]. 5131*/ 5132SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_db_status(sqlite3*, int op, int *pCur, int *pHiwtr, int resetFlg); 5133 5134/* 5135** CAPI3REF: Status Parameters for database connections 5136** EXPERIMENTAL 5137** 5138** These constants are the available integer "verbs" that can be passed as 5139** the second argument to the [sqlite3_db_status()] interface. 5140** 5141** New verbs may be added in future releases of SQLite. Existing verbs 5142** might be discontinued. Applications should check the return code from 5143** [sqlite3_db_status()] to make sure that the call worked. 5144** The [sqlite3_db_status()] interface will return a non-zero error code 5145** if a discontinued or unsupported verb is invoked. 5146** 5147** <dl> 5148** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt> 5149** <dd>This parameter returns the number of lookaside memory slots currently 5150** checked out.</dd>)^ 5151** </dl> 5152*/ 5153#define SQLITE_DBSTATUS_LOOKASIDE_USED 0 5154 5155 5156/* 5157** CAPI3REF: Prepared Statement Status 5158** EXPERIMENTAL 5159** 5160** ^(Each prepared statement maintains various 5161** [SQLITE_STMTSTATUS_SORT | counters] that measure the number 5162** of times it has performed specific operations.)^ These counters can 5163** be used to monitor the performance characteristics of the prepared 5164** statements. For example, if the number of table steps greatly exceeds 5165** the number of table searches or result rows, that would tend to indicate 5166** that the prepared statement is using a full table scan rather than 5167** an index. 5168** 5169** ^(This interface is used to retrieve and reset counter values from 5170** a [prepared statement]. The first argument is the prepared statement 5171** object to be interrogated. The second argument 5172** is an integer code for a specific [SQLITE_STMTSTATUS_SORT | counter] 5173** to be interrogated.)^ 5174** ^The current value of the requested counter is returned. 5175** ^If the resetFlg is true, then the counter is reset to zero after this 5176** interface call returns. 5177** 5178** See also: [sqlite3_status()] and [sqlite3_db_status()]. 5179*/ 5180SQLITE_API SQLITE_EXPERIMENTAL int sqlite3_stmt_status(sqlite3_stmt*, int op,int resetFlg); 5181 5182/* 5183** CAPI3REF: Status Parameters for prepared statements 5184** EXPERIMENTAL 5185** 5186** These preprocessor macros define integer codes that name counter 5187** values associated with the [sqlite3_stmt_status()] interface. 5188** The meanings of the various counters are as follows: 5189** 5190** <dl> 5191** <dt>SQLITE_STMTSTATUS_FULLSCAN_STEP</dt> 5192** <dd>^This is the number of times that SQLite has stepped forward in 5193** a table as part of a full table scan. Large numbers for this counter 5194** may indicate opportunities for performance improvement through 5195** careful use of indices.</dd> 5196** 5197** <dt>SQLITE_STMTSTATUS_SORT</dt> 5198** <dd>^This is the number of sort operations that have occurred. 5199** A non-zero value in this counter may indicate an opportunity to 5200** improvement performance through careful use of indices.</dd> 5201** 5202** </dl> 5203*/ 5204#define SQLITE_STMTSTATUS_FULLSCAN_STEP 1 5205#define SQLITE_STMTSTATUS_SORT 2 5206 5207/* 5208** CAPI3REF: Custom Page Cache Object 5209** EXPERIMENTAL 5210** 5211** The sqlite3_pcache type is opaque. It is implemented by 5212** the pluggable module. The SQLite core has no knowledge of 5213** its size or internal structure and never deals with the 5214** sqlite3_pcache object except by holding and passing pointers 5215** to the object. 5216** 5217** See [sqlite3_pcache_methods] for additional information. 5218*/ 5219typedef struct sqlite3_pcache sqlite3_pcache; 5220 5221/* 5222** CAPI3REF: Application Defined Page Cache. 5223** KEYWORDS: {page cache} 5224** EXPERIMENTAL 5225** 5226** ^(The [sqlite3_config]([SQLITE_CONFIG_PCACHE], ...) interface can 5227** register an alternative page cache implementation by passing in an 5228** instance of the sqlite3_pcache_methods structure.)^ The majority of the 5229** heap memory used by SQLite is used by the page cache to cache data read 5230** from, or ready to be written to, the database file. By implementing a 5231** custom page cache using this API, an application can control more 5232** precisely the amount of memory consumed by SQLite, the way in which 5233** that memory is allocated and released, and the policies used to 5234** determine exactly which parts of a database file are cached and for 5235** how long. 5236** 5237** ^(The contents of the sqlite3_pcache_methods structure are copied to an 5238** internal buffer by SQLite within the call to [sqlite3_config]. Hence 5239** the application may discard the parameter after the call to 5240** [sqlite3_config()] returns.)^ 5241** 5242** ^The xInit() method is called once for each call to [sqlite3_initialize()] 5243** (usually only once during the lifetime of the process). ^(The xInit() 5244** method is passed a copy of the sqlite3_pcache_methods.pArg value.)^ 5245** ^The xInit() method can set up up global structures and/or any mutexes 5246** required by the custom page cache implementation. 5247** 5248** ^The xShutdown() method is called from within [sqlite3_shutdown()], 5249** if the application invokes this API. It can be used to clean up 5250** any outstanding resources before process shutdown, if required. 5251** 5252** ^SQLite holds a [SQLITE_MUTEX_RECURSIVE] mutex when it invokes 5253** the xInit method, so the xInit method need not be threadsafe. ^The 5254** xShutdown method is only called from [sqlite3_shutdown()] so it does 5255** not need to be threadsafe either. All other methods must be threadsafe 5256** in multithreaded applications. 5257** 5258** ^SQLite will never invoke xInit() more than once without an intervening 5259** call to xShutdown(). 5260** 5261** ^The xCreate() method is used to construct a new cache instance. SQLite 5262** will typically create one cache instance for each open database file, 5263** though this is not guaranteed. ^The 5264** first parameter, szPage, is the size in bytes of the pages that must 5265** be allocated by the cache. ^szPage will not be a power of two. ^szPage 5266** will the page size of the database file that is to be cached plus an 5267** increment (here called "R") of about 100 or 200. ^SQLite will use the 5268** extra R bytes on each page to store metadata about the underlying 5269** database page on disk. The value of R depends 5270** on the SQLite version, the target platform, and how SQLite was compiled. 5271** ^R is constant for a particular build of SQLite. ^The second argument to 5272** xCreate(), bPurgeable, is true if the cache being created will 5273** be used to cache database pages of a file stored on disk, or 5274** false if it is used for an in-memory database. ^The cache implementation 5275** does not have to do anything special based with the value of bPurgeable; 5276** it is purely advisory. ^On a cache where bPurgeable is false, SQLite will 5277** never invoke xUnpin() except to deliberately delete a page. 5278** ^In other words, a cache created with bPurgeable set to false will 5279** never contain any unpinned pages. 5280** 5281** ^(The xCachesize() method may be called at any time by SQLite to set the 5282** suggested maximum cache-size (number of pages stored by) the cache 5283** instance passed as the first argument. This is the value configured using 5284** the SQLite "[PRAGMA cache_size]" command.)^ ^As with the bPurgeable 5285** parameter, the implementation is not required to do anything with this 5286** value; it is advisory only. 5287** 5288** ^The xPagecount() method should return the number of pages currently 5289** stored in the cache. 5290** 5291** ^The xFetch() method is used to fetch a page and return a pointer to it. 5292** ^A 'page', in this context, is a buffer of szPage bytes aligned at an 5293** 8-byte boundary. ^The page to be fetched is determined by the key. ^The 5294** mimimum key value is 1. After it has been retrieved using xFetch, the page 5295** is considered to be "pinned". 5296** 5297** ^If the requested page is already in the page cache, then the page cache 5298** implementation must return a pointer to the page buffer with its content 5299** intact. ^(If the requested page is not already in the cache, then the 5300** behavior of the cache implementation is determined by the value of the 5301** createFlag parameter passed to xFetch, according to the following table: 5302** 5303** <table border=1 width=85% align=center> 5304** <tr><th> createFlag <th> Behaviour when page is not already in cache 5305** <tr><td> 0 <td> Do not allocate a new page. Return NULL. 5306** <tr><td> 1 <td> Allocate a new page if it easy and convenient to do so. 5307** Otherwise return NULL. 5308** <tr><td> 2 <td> Make every effort to allocate a new page. Only return 5309** NULL if allocating a new page is effectively impossible. 5310** </table>)^ 5311** 5312** SQLite will normally invoke xFetch() with a createFlag of 0 or 1. If 5313** a call to xFetch() with createFlag==1 returns NULL, then SQLite will 5314** attempt to unpin one or more cache pages by spilling the content of 5315** pinned pages to disk and synching the operating system disk cache. After 5316** attempting to unpin pages, the xFetch() method will be invoked again with 5317** a createFlag of 2. 5318** 5319** ^xUnpin() is called by SQLite with a pointer to a currently pinned page 5320** as its second argument. ^(If the third parameter, discard, is non-zero, 5321** then the page should be evicted from the cache. In this case SQLite 5322** assumes that the next time the page is retrieved from the cache using 5323** the xFetch() method, it will be zeroed.)^ ^If the discard parameter is 5324** zero, then the page is considered to be unpinned. ^The cache implementation 5325** may choose to evict unpinned pages at any time. 5326** 5327** ^(The cache is not required to perform any reference counting. A single 5328** call to xUnpin() unpins the page regardless of the number of prior calls 5329** to xFetch().)^ 5330** 5331** ^The xRekey() method is used to change the key value associated with the 5332** page passed as the second argument from oldKey to newKey. ^If the cache 5333** previously contains an entry associated with newKey, it should be 5334** discarded. ^Any prior cache entry associated with newKey is guaranteed not 5335** to be pinned. 5336** 5337** ^When SQLite calls the xTruncate() method, the cache must discard all 5338** existing cache entries with page numbers (keys) greater than or equal 5339** to the value of the iLimit parameter passed to xTruncate(). ^If any 5340** of these pages are pinned, they are implicitly unpinned, meaning that 5341** they can be safely discarded. 5342** 5343** ^The xDestroy() method is used to delete a cache allocated by xCreate(). 5344** All resources associated with the specified cache should be freed. ^After 5345** calling the xDestroy() method, SQLite considers the [sqlite3_pcache*] 5346** handle invalid, and will not use it with any other sqlite3_pcache_methods 5347** functions. 5348*/ 5349typedef struct sqlite3_pcache_methods sqlite3_pcache_methods; 5350struct sqlite3_pcache_methods { 5351 void *pArg; 5352 int (*xInit)(void*); 5353 void (*xShutdown)(void*); 5354 sqlite3_pcache *(*xCreate)(int szPage, int bPurgeable); 5355 void (*xCachesize)(sqlite3_pcache*, int nCachesize); 5356 int (*xPagecount)(sqlite3_pcache*); 5357 void *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag); 5358 void (*xUnpin)(sqlite3_pcache*, void*, int discard); 5359 void (*xRekey)(sqlite3_pcache*, void*, unsigned oldKey, unsigned newKey); 5360 void (*xTruncate)(sqlite3_pcache*, unsigned iLimit); 5361 void (*xDestroy)(sqlite3_pcache*); 5362}; 5363 5364/* 5365** CAPI3REF: Online Backup Object 5366** EXPERIMENTAL 5367** 5368** The sqlite3_backup object records state information about an ongoing 5369** online backup operation. ^The sqlite3_backup object is created by 5370** a call to [sqlite3_backup_init()] and is destroyed by a call to 5371** [sqlite3_backup_finish()]. 5372** 5373** See Also: [Using the SQLite Online Backup API] 5374*/ 5375typedef struct sqlite3_backup sqlite3_backup; 5376 5377/* 5378** CAPI3REF: Online Backup API. 5379** EXPERIMENTAL 5380** 5381** The backup API copies the content of one database into another. 5382** It is useful either for creating backups of databases or 5383** for copying in-memory databases to or from persistent files. 5384** 5385** See Also: [Using the SQLite Online Backup API] 5386** 5387** ^Exclusive access is required to the destination database for the 5388** duration of the operation. ^However the source database is only 5389** read-locked while it is actually being read; it is not locked 5390** continuously for the entire backup operation. ^Thus, the backup may be 5391** performed on a live source database without preventing other users from 5392** reading or writing to the source database while the backup is underway. 5393** 5394** ^(To perform a backup operation: 5395** <ol> 5396** <li><b>sqlite3_backup_init()</b> is called once to initialize the 5397** backup, 5398** <li><b>sqlite3_backup_step()</b> is called one or more times to transfer 5399** the data between the two databases, and finally 5400** <li><b>sqlite3_backup_finish()</b> is called to release all resources 5401** associated with the backup operation. 5402** </ol>)^ 5403** There should be exactly one call to sqlite3_backup_finish() for each 5404** successful call to sqlite3_backup_init(). 5405** 5406** <b>sqlite3_backup_init()</b> 5407** 5408** ^The D and N arguments to sqlite3_backup_init(D,N,S,M) are the 5409** [database connection] associated with the destination database 5410** and the database name, respectively. 5411** ^The database name is "main" for the main database, "temp" for the 5412** temporary database, or the name specified after the AS keyword in 5413** an [ATTACH] statement for an attached database. 5414** ^The S and M arguments passed to 5415** sqlite3_backup_init(D,N,S,M) identify the [database connection] 5416** and database name of the source database, respectively. 5417** ^The source and destination [database connections] (parameters S and D) 5418** must be different or else sqlite3_backup_init(D,N,S,M) will file with 5419** an error. 5420** 5421** ^If an error occurs within sqlite3_backup_init(D,N,S,M), then NULL is 5422** returned and an error code and error message are store3d in the 5423** destination [database connection] D. 5424** ^The error code and message for the failed call to sqlite3_backup_init() 5425** can be retrieved using the [sqlite3_errcode()], [sqlite3_errmsg()], and/or 5426** [sqlite3_errmsg16()] functions. 5427** ^A successful call to sqlite3_backup_init() returns a pointer to an 5428** [sqlite3_backup] object. 5429** ^The [sqlite3_backup] object may be used with the sqlite3_backup_step() and 5430** sqlite3_backup_finish() functions to perform the specified backup 5431** operation. 5432** 5433** <b>sqlite3_backup_step()</b> 5434** 5435** ^Function sqlite3_backup_step(B,N) will copy up to N pages between 5436** the source and destination databases specified by [sqlite3_backup] object B. 5437** ^If N is negative, all remaining source pages are copied. 5438** ^If sqlite3_backup_step(B,N) successfully copies N pages and there 5439** are still more pages to be copied, then the function resturns [SQLITE_OK]. 5440** ^If sqlite3_backup_step(B,N) successfully finishes copying all pages 5441** from source to destination, then it returns [SQLITE_DONE]. 5442** ^If an error occurs while running sqlite3_backup_step(B,N), 5443** then an [error code] is returned. ^As well as [SQLITE_OK] and 5444** [SQLITE_DONE], a call to sqlite3_backup_step() may return [SQLITE_READONLY], 5445** [SQLITE_NOMEM], [SQLITE_BUSY], [SQLITE_LOCKED], or an 5446** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX] extended error code. 5447** 5448** ^The sqlite3_backup_step() might return [SQLITE_READONLY] if the destination 5449** database was opened read-only or if 5450** the destination is an in-memory database with a different page size 5451** from the source database. 5452** 5453** ^If sqlite3_backup_step() cannot obtain a required file-system lock, then 5454** the [sqlite3_busy_handler | busy-handler function] 5455** is invoked (if one is specified). ^If the 5456** busy-handler returns non-zero before the lock is available, then 5457** [SQLITE_BUSY] is returned to the caller. ^In this case the call to 5458** sqlite3_backup_step() can be retried later. ^If the source 5459** [database connection] 5460** is being used to write to the source database when sqlite3_backup_step() 5461** is called, then [SQLITE_LOCKED] is returned immediately. ^Again, in this 5462** case the call to sqlite3_backup_step() can be retried later on. ^(If 5463** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX], [SQLITE_NOMEM], or 5464** [SQLITE_READONLY] is returned, then 5465** there is no point in retrying the call to sqlite3_backup_step(). These 5466** errors are considered fatal.)^ The application must accept 5467** that the backup operation has failed and pass the backup operation handle 5468** to the sqlite3_backup_finish() to release associated resources. 5469** 5470** ^The first call to sqlite3_backup_step() obtains an exclusive lock 5471** on the destination file. ^The exclusive lock is not released until either 5472** sqlite3_backup_finish() is called or the backup operation is complete 5473** and sqlite3_backup_step() returns [SQLITE_DONE]. ^Every call to 5474** sqlite3_backup_step() obtains a [shared lock] on the source database that 5475** lasts for the duration of the sqlite3_backup_step() call. 5476** ^Because the source database is not locked between calls to 5477** sqlite3_backup_step(), the source database may be modified mid-way 5478** through the backup process. ^If the source database is modified by an 5479** external process or via a database connection other than the one being 5480** used by the backup operation, then the backup will be automatically 5481** restarted by the next call to sqlite3_backup_step(). ^If the source 5482** database is modified by the using the same database connection as is used 5483** by the backup operation, then the backup database is automatically 5484** updated at the same time. 5485** 5486** <b>sqlite3_backup_finish()</b> 5487** 5488** When sqlite3_backup_step() has returned [SQLITE_DONE], or when the 5489** application wishes to abandon the backup operation, the application 5490** should destroy the [sqlite3_backup] by passing it to sqlite3_backup_finish(). 5491** ^The sqlite3_backup_finish() interfaces releases all 5492** resources associated with the [sqlite3_backup] object. 5493** ^If sqlite3_backup_step() has not yet returned [SQLITE_DONE], then any 5494** active write-transaction on the destination database is rolled back. 5495** The [sqlite3_backup] object is invalid 5496** and may not be used following a call to sqlite3_backup_finish(). 5497** 5498** ^The value returned by sqlite3_backup_finish is [SQLITE_OK] if no 5499** sqlite3_backup_step() errors occurred, regardless or whether or not 5500** sqlite3_backup_step() completed. 5501** ^If an out-of-memory condition or IO error occurred during any prior 5502** sqlite3_backup_step() call on the same [sqlite3_backup] object, then 5503** sqlite3_backup_finish() returns the corresponding [error code]. 5504** 5505** ^A return of [SQLITE_BUSY] or [SQLITE_LOCKED] from sqlite3_backup_step() 5506** is not a permanent error and does not affect the return value of 5507** sqlite3_backup_finish(). 5508** 5509** <b>sqlite3_backup_remaining(), sqlite3_backup_pagecount()</b> 5510** 5511** ^Each call to sqlite3_backup_step() sets two values inside 5512** the [sqlite3_backup] object: the number of pages still to be backed 5513** up and the total number of pages in the source databae file. 5514** The sqlite3_backup_remaining() and sqlite3_backup_pagecount() interfaces 5515** retrieve these two values, respectively. 5516** 5517** ^The values returned by these functions are only updated by 5518** sqlite3_backup_step(). ^If the source database is modified during a backup 5519** operation, then the values are not updated to account for any extra 5520** pages that need to be updated or the size of the source database file 5521** changing. 5522** 5523** <b>Concurrent Usage of Database Handles</b> 5524** 5525** ^The source [database connection] may be used by the application for other 5526** purposes while a backup operation is underway or being initialized. 5527** ^If SQLite is compiled and configured to support threadsafe database 5528** connections, then the source database connection may be used concurrently 5529** from within other threads. 5530** 5531** However, the application must guarantee that the destination 5532** [database connection] is not passed to any other API (by any thread) after 5533** sqlite3_backup_init() is called and before the corresponding call to 5534** sqlite3_backup_finish(). SQLite does not currently check to see 5535** if the application incorrectly accesses the destination [database connection] 5536** and so no error code is reported, but the operations may malfunction 5537** nevertheless. Use of the destination database connection while a 5538** backup is in progress might also also cause a mutex deadlock. 5539** 5540** If running in [shared cache mode], the application must 5541** guarantee that the shared cache used by the destination database 5542** is not accessed while the backup is running. In practice this means 5543** that the application must guarantee that the disk file being 5544** backed up to is not accessed by any connection within the process, 5545** not just the specific connection that was passed to sqlite3_backup_init(). 5546** 5547** The [sqlite3_backup] object itself is partially threadsafe. Multiple 5548** threads may safely make multiple concurrent calls to sqlite3_backup_step(). 5549** However, the sqlite3_backup_remaining() and sqlite3_backup_pagecount() 5550** APIs are not strictly speaking threadsafe. If they are invoked at the 5551** same time as another thread is invoking sqlite3_backup_step() it is 5552** possible that they return invalid values. 5553*/ 5554SQLITE_API sqlite3_backup *sqlite3_backup_init( 5555 sqlite3 *pDest, /* Destination database handle */ 5556 const char *zDestName, /* Destination database name */ 5557 sqlite3 *pSource, /* Source database handle */ 5558 const char *zSourceName /* Source database name */ 5559); 5560SQLITE_API int sqlite3_backup_step(sqlite3_backup *p, int nPage); 5561SQLITE_API int sqlite3_backup_finish(sqlite3_backup *p); 5562SQLITE_API int sqlite3_backup_remaining(sqlite3_backup *p); 5563SQLITE_API int sqlite3_backup_pagecount(sqlite3_backup *p); 5564 5565/* 5566** CAPI3REF: Unlock Notification 5567** EXPERIMENTAL 5568** 5569** ^When running in shared-cache mode, a database operation may fail with 5570** an [SQLITE_LOCKED] error if the required locks on the shared-cache or 5571** individual tables within the shared-cache cannot be obtained. See 5572** [SQLite Shared-Cache Mode] for a description of shared-cache locking. 5573** ^This API may be used to register a callback that SQLite will invoke 5574** when the connection currently holding the required lock relinquishes it. 5575** ^This API is only available if the library was compiled with the 5576** [SQLITE_ENABLE_UNLOCK_NOTIFY] C-preprocessor symbol defined. 5577** 5578** See Also: [Using the SQLite Unlock Notification Feature]. 5579** 5580** ^Shared-cache locks are released when a database connection concludes 5581** its current transaction, either by committing it or rolling it back. 5582** 5583** ^When a connection (known as the blocked connection) fails to obtain a 5584** shared-cache lock and SQLITE_LOCKED is returned to the caller, the 5585** identity of the database connection (the blocking connection) that 5586** has locked the required resource is stored internally. ^After an 5587** application receives an SQLITE_LOCKED error, it may call the 5588** sqlite3_unlock_notify() method with the blocked connection handle as 5589** the first argument to register for a callback that will be invoked 5590** when the blocking connections current transaction is concluded. ^The 5591** callback is invoked from within the [sqlite3_step] or [sqlite3_close] 5592** call that concludes the blocking connections transaction. 5593** 5594** ^(If sqlite3_unlock_notify() is called in a multi-threaded application, 5595** there is a chance that the blocking connection will have already 5596** concluded its transaction by the time sqlite3_unlock_notify() is invoked. 5597** If this happens, then the specified callback is invoked immediately, 5598** from within the call to sqlite3_unlock_notify().)^ 5599** 5600** ^If the blocked connection is attempting to obtain a write-lock on a 5601** shared-cache table, and more than one other connection currently holds 5602** a read-lock on the same table, then SQLite arbitrarily selects one of 5603** the other connections to use as the blocking connection. 5604** 5605** ^(There may be at most one unlock-notify callback registered by a 5606** blocked connection. If sqlite3_unlock_notify() is called when the 5607** blocked connection already has a registered unlock-notify callback, 5608** then the new callback replaces the old.)^ ^If sqlite3_unlock_notify() is 5609** called with a NULL pointer as its second argument, then any existing 5610** unlock-notify callback is cancelled. ^The blocked connections 5611** unlock-notify callback may also be canceled by closing the blocked 5612** connection using [sqlite3_close()]. 5613** 5614** The unlock-notify callback is not reentrant. If an application invokes 5615** any sqlite3_xxx API functions from within an unlock-notify callback, a 5616** crash or deadlock may be the result. 5617** 5618** ^Unless deadlock is detected (see below), sqlite3_unlock_notify() always 5619** returns SQLITE_OK. 5620** 5621** <b>Callback Invocation Details</b> 5622** 5623** When an unlock-notify callback is registered, the application provides a 5624** single void* pointer that is passed to the callback when it is invoked. 5625** However, the signature of the callback function allows SQLite to pass 5626** it an array of void* context pointers. The first argument passed to 5627** an unlock-notify callback is a pointer to an array of void* pointers, 5628** and the second is the number of entries in the array. 5629** 5630** When a blocking connections transaction is concluded, there may be 5631** more than one blocked connection that has registered for an unlock-notify 5632** callback. ^If two or more such blocked connections have specified the 5633** same callback function, then instead of invoking the callback function 5634** multiple times, it is invoked once with the set of void* context pointers 5635** specified by the blocked connections bundled together into an array. 5636** This gives the application an opportunity to prioritize any actions 5637** related to the set of unblocked database connections. 5638** 5639** <b>Deadlock Detection</b> 5640** 5641** Assuming that after registering for an unlock-notify callback a 5642** database waits for the callback to be issued before taking any further 5643** action (a reasonable assumption), then using this API may cause the 5644** application to deadlock. For example, if connection X is waiting for 5645** connection Y's transaction to be concluded, and similarly connection 5646** Y is waiting on connection X's transaction, then neither connection 5647** will proceed and the system may remain deadlocked indefinitely. 5648** 5649** To avoid this scenario, the sqlite3_unlock_notify() performs deadlock 5650** detection. ^If a given call to sqlite3_unlock_notify() would put the 5651** system in a deadlocked state, then SQLITE_LOCKED is returned and no 5652** unlock-notify callback is registered. The system is said to be in 5653** a deadlocked state if connection A has registered for an unlock-notify 5654** callback on the conclusion of connection B's transaction, and connection 5655** B has itself registered for an unlock-notify callback when connection 5656** A's transaction is concluded. ^Indirect deadlock is also detected, so 5657** the system is also considered to be deadlocked if connection B has 5658** registered for an unlock-notify callback on the conclusion of connection 5659** C's transaction, where connection C is waiting on connection A. ^Any 5660** number of levels of indirection are allowed. 5661** 5662** <b>The "DROP TABLE" Exception</b> 5663** 5664** When a call to [sqlite3_step()] returns SQLITE_LOCKED, it is almost 5665** always appropriate to call sqlite3_unlock_notify(). There is however, 5666** one exception. When executing a "DROP TABLE" or "DROP INDEX" statement, 5667** SQLite checks if there are any currently executing SELECT statements 5668** that belong to the same connection. If there are, SQLITE_LOCKED is 5669** returned. In this case there is no "blocking connection", so invoking 5670** sqlite3_unlock_notify() results in the unlock-notify callback being 5671** invoked immediately. If the application then re-attempts the "DROP TABLE" 5672** or "DROP INDEX" query, an infinite loop might be the result. 5673** 5674** One way around this problem is to check the extended error code returned 5675** by an sqlite3_step() call. ^(If there is a blocking connection, then the 5676** extended error code is set to SQLITE_LOCKED_SHAREDCACHE. Otherwise, in 5677** the special "DROP TABLE/INDEX" case, the extended error code is just 5678** SQLITE_LOCKED.)^ 5679*/ 5680SQLITE_API int sqlite3_unlock_notify( 5681 sqlite3 *pBlocked, /* Waiting connection */ 5682 void (*xNotify)(void **apArg, int nArg), /* Callback function to invoke */ 5683 void *pNotifyArg /* Argument to pass to xNotify */ 5684); 5685 5686 5687/* 5688** CAPI3REF: String Comparison 5689** EXPERIMENTAL 5690** 5691** ^The [sqlite3_strnicmp()] API allows applications and extensions to 5692** compare the contents of two buffers containing UTF-8 strings in a 5693** case-indendent fashion, using the same definition of case independence 5694** that SQLite uses internally when comparing identifiers. 5695*/ 5696SQLITE_API int sqlite3_strnicmp(const char *, const char *, int); 5697 5698/* 5699** CAPI3REF: Error Logging Interface 5700** EXPERIMENTAL 5701** 5702** ^The [sqlite3_log()] interface writes a message into the error log 5703** established by the [SQLITE_CONFIG_LOG] option to [sqlite3_config()]. 5704** ^If logging is enabled, the zFormat string and subsequent arguments are 5705** passed through to [sqlite3_vmprintf()] to generate the final output string. 5706** 5707** The sqlite3_log() interface is intended for use by extensions such as 5708** virtual tables, collating functions, and SQL functions. While there is 5709** nothing to prevent an application from calling sqlite3_log(), doing so 5710** is considered bad form. 5711** 5712** The zFormat string must not be NULL. 5713** 5714** To avoid deadlocks and other threading problems, the sqlite3_log() routine 5715** will not use dynamically allocated memory. The log message is stored in 5716** a fixed-length buffer on the stack. If the log message is longer than 5717** a few hundred characters, it will be truncated to the length of the 5718** buffer. 5719*/ 5720SQLITE_API void sqlite3_log(int iErrCode, const char *zFormat, ...); 5721 5722/* 5723** Undo the hack that converts floating point types to integer for 5724** builds on processors without floating point support. 5725*/ 5726#ifdef SQLITE_OMIT_FLOATING_POINT 5727# undef double 5728#endif 5729 5730#ifdef __cplusplus 5731} /* End of the 'extern "C"' block */ 5732#endif 5733#endif 5734 5735