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** 2001 September 15
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
** This header file defines the interface that the SQLite library
** presents to client programs. If a C-function, structure, datatype,
** or constant definition does not appear in this file, then it is
** not a published API of SQLite, is subject to change without
** notice, and should not be referenced by programs that use SQLite.
** Some of the definitions that are in this file are marked as
** "experimental". Experimental interfaces are normally new
** features recently added to SQLite. We do not anticipate changes
** to experimental interfaces but reserve the right to make minor changes
** if experience from use "in the wild" suggest such changes are prudent.
** The official C-language API documentation for SQLite is derived
** from comments in this file. This file is the authoritative source
** on how SQLite interfaces are suppose to operate.
** The name of this file under configuration management is "".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h> /* Needed for the definition of va_list */
** Make sure we can call this stuff from C++.
#ifdef __cplusplus
extern "C" {
** Add the ability to override 'extern'
# define SQLITE_EXTERN extern
#ifndef SQLITE_API
# define SQLITE_API
** These no-op macros are used in front of interfaces to mark those
** interfaces as either deprecated or experimental. New applications
** should not use deprecated interfaces - they are support for backwards
** compatibility only. Application writers should be aware that
** experimental interfaces are subject to change in point releases.
** These macros used to resolve to various kinds of compiler magic that
** would generate warning messages when they were used. But that
** compiler magic ended up generating such a flurry of bug reports
** that we have taken it all out and gone back to using simple
** noop macros.
** Ensure these symbols were not defined by some previous header file.
** CAPI3REF: Compile-Time Library Version Numbers
** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header
** evaluates to a string literal that is the SQLite version in the
** format "X.Y.Z" where X is the major version number (always 3 for
** SQLite3) and Y is the minor version number and Z is the release number.)^
** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer
** with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z are the same
** numbers used in [SQLITE_VERSION].)^
** The SQLITE_VERSION_NUMBER for any given release of SQLite will also
** be larger than the release from which it is derived. Either Y will
** be held constant and Z will be incremented or else Y will be incremented
** and Z will be reset to zero.
** Since version 3.6.18, SQLite source code has been stored in the
** <a href="">Fossil configuration management
** system</a>. ^The SQLITE_SOURCE_ID macro evaluates to
** a string which identifies a particular check-in of SQLite
** within its configuration management system. ^The SQLITE_SOURCE_ID
** string contains the date and time of the check-in (UTC) and an SHA1
** hash of the entire source tree.
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
#define SQLITE_VERSION "3.8.2"
#define SQLITE_SOURCE_ID "2013-12-06 14:53:30 27392118af4c38c5203a04b8013e1afdb1cebd0d"
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
** but are associated with the library instead of the header file. ^(Cautious
** programmers might include assert() statements in their application to
** verify that values returned by these interfaces match the macros in
** the header, and thus insure that the application is
** compiled with matching library and header files.
** <blockquote><pre>
** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );
** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
** </pre></blockquote>)^
** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
** macro. ^The sqlite3_libversion() function returns a pointer to the
** to the sqlite3_version[] string constant. The sqlite3_libversion()
** function is provided for use in DLLs since DLL users usually do not have
** direct access to string constants within the DLL. ^The
** sqlite3_libversion_number() function returns an integer equal to
** [SQLITE_VERSION_NUMBER]. ^The sqlite3_sourceid() function returns
** a pointer to a string constant whose value is the same as the
** [SQLITE_SOURCE_ID] C preprocessor macro.
** See also: [sqlite_version()] and [sqlite_source_id()].
SQLITE_API SQLITE_EXTERN const char sqlite3_version[];
SQLITE_API const char *sqlite3_libversion(void);
SQLITE_API const char *sqlite3_sourceid(void);
SQLITE_API int sqlite3_libversion_number(void);
** CAPI3REF: Run-Time Library Compilation Options Diagnostics
** ^The sqlite3_compileoption_used() function returns 0 or 1
** indicating whether the specified option was defined at
** compile time. ^The SQLITE_ prefix may be omitted from the
** option name passed to sqlite3_compileoption_used().
** ^The sqlite3_compileoption_get() function allows iterating
** over the list of options that were defined at compile time by
** returning the N-th compile time option string. ^If N is out of range,
** sqlite3_compileoption_get() returns a NULL pointer. ^The SQLITE_
** prefix is omitted from any strings returned by
** sqlite3_compileoption_get().
** ^Support for the diagnostic functions sqlite3_compileoption_used()
** and sqlite3_compileoption_get() may be omitted by specifying the
** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
** See also: SQL functions [sqlite_compileoption_used()] and
** [sqlite_compileoption_get()] and the [compile_options pragma].
SQLITE_API int sqlite3_compileoption_used(const char *zOptName);
SQLITE_API const char *sqlite3_compileoption_get(int N);
** CAPI3REF: Test To See If The Library Is Threadsafe
** ^The sqlite3_threadsafe() function returns zero if and only if
** SQLite was compiled with mutexing code omitted due to the
** [SQLITE_THREADSAFE] compile-time option being set to 0.
** SQLite can be compiled with or without mutexes. When
** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes
** are enabled and SQLite is threadsafe. When the
** [SQLITE_THREADSAFE] macro is 0,
** the mutexes are omitted. Without the mutexes, it is not safe
** to use SQLite concurrently from more than one thread.
** Enabling mutexes incurs a measurable performance penalty.
** So if speed is of utmost importance, it makes sense to disable
** the mutexes. But for maximum safety, mutexes should be enabled.
** ^The default behavior is for mutexes to be enabled.
** This interface can be used by an application to make sure that the
** version of SQLite that it is linking against was compiled with
** the desired setting of the [SQLITE_THREADSAFE] macro.
** This interface only reports on the compile-time mutex setting
** of the [SQLITE_THREADSAFE] flag. If SQLite is compiled with
** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but
** can be fully or partially disabled using a call to [sqlite3_config()]
** or [SQLITE_CONFIG_MUTEX]. ^(The return value of the
** sqlite3_threadsafe() function shows only the compile-time setting of
** thread safety, not any run-time changes to that setting made by
** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()
** is unchanged by calls to sqlite3_config().)^
** See the [threading mode] documentation for additional information.
SQLITE_API int sqlite3_threadsafe(void);
** CAPI3REF: Database Connection Handle
** KEYWORDS: {database connection} {database connections}
** Each open SQLite database is represented by a pointer to an instance of
** the opaque structure named "sqlite3". It is useful to think of an sqlite3
** pointer as an object. The [sqlite3_open()], [sqlite3_open16()], and
** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
** and [sqlite3_close_v2()] are its destructors. There are many other
** interfaces (such as
** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
** [sqlite3_busy_timeout()] to name but three) that are methods on an
** sqlite3 object.
typedef struct sqlite3 sqlite3;
** CAPI3REF: 64-Bit Integer Types
** KEYWORDS: sqlite_int64 sqlite_uint64
** Because there is no cross-platform way to specify 64-bit integer types
** SQLite includes typedefs for 64-bit signed and unsigned integers.
** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
** The sqlite_int64 and sqlite_uint64 types are supported for backwards
** compatibility only.
** ^The sqlite3_int64 and sqlite_int64 types can store integer values
** between -9223372036854775808 and +9223372036854775807 inclusive. ^The
** sqlite3_uint64 and sqlite_uint64 types can store integer values
** between 0 and +18446744073709551615 inclusive.
typedef SQLITE_INT64_TYPE sqlite_int64;
typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;
#elif defined(_MSC_VER) || defined(__BORLANDC__)
typedef __int64 sqlite_int64;
typedef unsigned __int64 sqlite_uint64;
typedef long long int sqlite_int64;
typedef unsigned long long int sqlite_uint64;
typedef sqlite_int64 sqlite3_int64;
typedef sqlite_uint64 sqlite3_uint64;
** If compiling for a processor that lacks floating point support,
** substitute integer for floating-point.
# define double sqlite3_int64
** CAPI3REF: Closing A Database Connection
** ^The sqlite3_close() and sqlite3_close_v2() routines are destructors
** for the [sqlite3] object.
** ^Calls to sqlite3_close() and sqlite3_close_v2() return SQLITE_OK if
** the [sqlite3] object is successfully destroyed and all associated
** resources are deallocated.
** ^If the database connection is associated with unfinalized prepared
** statements or unfinished sqlite3_backup objects then sqlite3_close()
** will leave the database connection open and return [SQLITE_BUSY].
** ^If sqlite3_close_v2() is called with unfinalized prepared statements
** and unfinished sqlite3_backups, then the database connection becomes
** an unusable "zombie" which will automatically be deallocated when the
** last prepared statement is finalized or the last sqlite3_backup is
** finished. The sqlite3_close_v2() interface is intended for use with
** host languages that are garbage collected, and where the order in which
** destructors are called is arbitrary.
** Applications should [sqlite3_finalize | finalize] all [prepared statements],
** [sqlite3_blob_close | close] all [BLOB handles], and
** [sqlite3_backup_finish | finish] all [sqlite3_backup] objects associated
** with the [sqlite3] object prior to attempting to close the object. ^If
** sqlite3_close_v2() is called on a [database connection] that still has
** outstanding [prepared statements], [BLOB handles], and/or
** [sqlite3_backup] objects then it returns SQLITE_OK but the deallocation
** of resources is deferred until all [prepared statements], [BLOB handles],
** and [sqlite3_backup] objects are also destroyed.
** ^If an [sqlite3] object is destroyed while a transaction is open,
** the transaction is automatically rolled back.
** The C parameter to [sqlite3_close(C)] and [sqlite3_close_v2(C)]
** must be either a NULL
** pointer or an [sqlite3] object pointer obtained
** from [sqlite3_open()], [sqlite3_open16()], or
** [sqlite3_open_v2()], and not previously closed.
** ^Calling sqlite3_close() or sqlite3_close_v2() with a NULL pointer
** argument is a harmless no-op.
SQLITE_API int sqlite3_close(sqlite3*);
SQLITE_API int sqlite3_close_v2(sqlite3*);
** The type for a callback function.
** This is legacy and deprecated. It is included for historical
** compatibility and is not documented.
typedef int (*sqlite3_callback)(void*,int,char**, char**);
** CAPI3REF: One-Step Query Execution Interface
** The sqlite3_exec() interface is a convenience wrapper around
** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],
** that allows an application to run multiple statements of SQL
** without having to use a lot of C code.
** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
** semicolon-separate SQL statements passed into its 2nd argument,
** in the context of the [database connection] passed in as its 1st
** argument. ^If the callback function of the 3rd argument to
** sqlite3_exec() is not NULL, then it is invoked for each result row
** coming out of the evaluated SQL statements. ^The 4th argument to
** sqlite3_exec() is relayed through to the 1st argument of each
** callback invocation. ^If the callback pointer to sqlite3_exec()
** is NULL, then no callback is ever invoked and result rows are
** ignored.
** ^If an error occurs while evaluating the SQL statements passed into
** sqlite3_exec(), then execution of the current statement stops and
** subsequent statements are skipped. ^If the 5th parameter to sqlite3_exec()
** is not NULL then any error message is written into memory obtained
** from [sqlite3_malloc()] and passed back through the 5th parameter.
** To avoid memory leaks, the application should invoke [sqlite3_free()]
** on error message strings returned through the 5th parameter of
** of sqlite3_exec() after the error message string is no longer needed.
** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
** NULL before returning.
** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()
** routine returns SQLITE_ABORT without invoking the callback again and
** without running any subsequent SQL statements.
** ^The 2nd argument to the sqlite3_exec() callback function is the
** number of columns in the result. ^The 3rd argument to the sqlite3_exec()
** callback is an array of pointers to strings obtained as if from
** [sqlite3_column_text()], one for each column. ^If an element of a
** result row is NULL then the corresponding string pointer for the
** sqlite3_exec() callback is a NULL pointer. ^The 4th argument to the
** sqlite3_exec() callback is an array of pointers to strings where each
** entry represents the name of corresponding result column as obtained
** from [sqlite3_column_name()].
** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer
** to an empty string, or a pointer that contains only whitespace and/or
** SQL comments, then no SQL statements are evaluated and the database
** is not changed.
** Restrictions:
** <ul>
** <li> The application must insure that the 1st parameter to sqlite3_exec()
** is a valid and open [database connection].
** <li> The application must not close the [database connection] specified by
** the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
** <li> The application must not modify the SQL statement text passed into
** the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.
** </ul>
SQLITE_API int sqlite3_exec(
sqlite3*, /* An open database */
const char *sql, /* SQL to be evaluated */
int (*callback)(void*,int,char**,char**), /* Callback function */
void *, /* 1st argument to callback */
char **errmsg /* Error msg written here */
** CAPI3REF: Result Codes
** KEYWORDS: SQLITE_OK {error code} {error codes}
** KEYWORDS: {result code} {result codes}
** Many SQLite functions return an integer result code from the set shown
** here in order to indicate success or failure.
** New error codes may be added in future versions of SQLite.
** See also: [SQLITE_IOERR_READ | extended result codes],
** [sqlite3_vtab_on_conflict()] [SQLITE_ROLLBACK | result codes].
#define SQLITE_OK 0 /* Successful result */
/* beginning-of-error-codes */
#define SQLITE_ERROR 1 /* SQL error or missing database */
#define SQLITE_INTERNAL 2 /* Internal logic error in SQLite */
#define SQLITE_PERM 3 /* Access permission denied */
#define SQLITE_ABORT 4 /* Callback routine requested an abort */
#define SQLITE_BUSY 5 /* The database file is locked */
#define SQLITE_LOCKED 6 /* A table in the database is locked */
#define SQLITE_NOMEM 7 /* A malloc() failed */
#define SQLITE_READONLY 8 /* Attempt to write a readonly database */
#define SQLITE_INTERRUPT 9 /* Operation terminated by sqlite3_interrupt()*/
#define SQLITE_IOERR 10 /* Some kind of disk I/O error occurred */
#define SQLITE_CORRUPT 11 /* The database disk image is malformed */
#define SQLITE_NOTFOUND 12 /* Unknown opcode in sqlite3_file_control() */
#define SQLITE_FULL 13 /* Insertion failed because database is full */
#define SQLITE_CANTOPEN 14 /* Unable to open the database file */
#define SQLITE_PROTOCOL 15 /* Database lock protocol error */
#define SQLITE_EMPTY 16 /* Database is empty */
#define SQLITE_SCHEMA 17 /* The database schema changed */
#define SQLITE_TOOBIG 18 /* String or BLOB exceeds size limit */
#define SQLITE_CONSTRAINT 19 /* Abort due to constraint violation */
#define SQLITE_MISMATCH 20 /* Data type mismatch */
#define SQLITE_MISUSE 21 /* Library used incorrectly */
#define SQLITE_NOLFS 22 /* Uses OS features not supported on host */
#define SQLITE_AUTH 23 /* Authorization denied */
#define SQLITE_FORMAT 24 /* Auxiliary database format error */
#define SQLITE_RANGE 25 /* 2nd parameter to sqlite3_bind out of range */
#define SQLITE_NOTADB 26 /* File opened that is not a database file */
#define SQLITE_NOTICE 27 /* Notifications from sqlite3_log() */
#define SQLITE_WARNING 28 /* Warnings from sqlite3_log() */
#define SQLITE_ROW 100 /* sqlite3_step() has another row ready */
#define SQLITE_DONE 101 /* sqlite3_step() has finished executing */
/* end-of-error-codes */
** CAPI3REF: Extended Result Codes
** KEYWORDS: {extended error code} {extended error codes}
** KEYWORDS: {extended result code} {extended result codes}
** In its default configuration, SQLite API routines return one of 26 integer
** [SQLITE_OK | result codes]. However, experience has shown that many of
** these result codes are too coarse-grained. They do not provide as
** much information about problems as programmers might like. In an effort to
** address this, newer versions of SQLite (version 3.3.8 and later) include
** support for additional result codes that provide more detailed information
** about errors. The extended result codes are enabled or disabled
** on a per database connection basis using the
** [sqlite3_extended_result_codes()] API.
** Some of the available extended result codes are listed here.
** One may expect the number of extended result codes will increase
** over time. Software that uses extended result codes should expect
** to see new result codes in future releases of SQLite.
** The SQLITE_OK result code will never be extended. It will always
** be exactly zero.
** CAPI3REF: Flags For File Open Operations
** These bit values are intended for use in the
** 3rd parameter to the [sqlite3_open_v2()] interface and
** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
#define SQLITE_OPEN_READONLY 0x00000001 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_READWRITE 0x00000002 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_CREATE 0x00000004 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_DELETEONCLOSE 0x00000008 /* VFS only */
#define SQLITE_OPEN_EXCLUSIVE 0x00000010 /* VFS only */
#define SQLITE_OPEN_AUTOPROXY 0x00000020 /* VFS only */
#define SQLITE_OPEN_URI 0x00000040 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_MEMORY 0x00000080 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_MAIN_DB 0x00000100 /* VFS only */
#define SQLITE_OPEN_TEMP_DB 0x00000200 /* VFS only */
#define SQLITE_OPEN_TRANSIENT_DB 0x00000400 /* VFS only */
#define SQLITE_OPEN_MAIN_JOURNAL 0x00000800 /* VFS only */
#define SQLITE_OPEN_TEMP_JOURNAL 0x00001000 /* VFS only */
#define SQLITE_OPEN_SUBJOURNAL 0x00002000 /* VFS only */
#define SQLITE_OPEN_MASTER_JOURNAL 0x00004000 /* VFS only */
#define SQLITE_OPEN_NOMUTEX 0x00008000 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_FULLMUTEX 0x00010000 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_SHAREDCACHE 0x00020000 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_PRIVATECACHE 0x00040000 /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_WAL 0x00080000 /* VFS only */
/* Reserved: 0x00F00000 */
** CAPI3REF: Device Characteristics
** The xDeviceCharacteristics method of the [sqlite3_io_methods]
** object returns an integer which is a vector of these
** bit values expressing I/O characteristics of the mass storage
** device that holds the file that the [sqlite3_io_methods]
** refers to.
** The SQLITE_IOCAP_ATOMIC property means that all writes of
** any size are atomic. The SQLITE_IOCAP_ATOMICnnn values
** mean that writes of blocks that are nnn bytes in size and
** are aligned to an address which is an integer multiple of
** nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means
** that when data is appended to a file, the data is appended
** first then the size of the file is extended, never the other
** way around. The SQLITE_IOCAP_SEQUENTIAL property means that
** information is written to disk in the same order as calls
** to xWrite(). The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that
** after reboot following a crash or power loss, the only bytes in a
** file that were written at the application level might have changed
** and that adjacent bytes, even bytes within the same sector are
** guaranteed to be unchanged.
#define SQLITE_IOCAP_ATOMIC 0x00000001
#define SQLITE_IOCAP_ATOMIC512 0x00000002
#define SQLITE_IOCAP_ATOMIC1K 0x00000004
#define SQLITE_IOCAP_ATOMIC2K 0x00000008
#define SQLITE_IOCAP_ATOMIC4K 0x00000010
#define SQLITE_IOCAP_ATOMIC8K 0x00000020
#define SQLITE_IOCAP_ATOMIC16K 0x00000040
#define SQLITE_IOCAP_ATOMIC32K 0x00000080
#define SQLITE_IOCAP_ATOMIC64K 0x00000100
#define SQLITE_IOCAP_SAFE_APPEND 0x00000200
#define SQLITE_IOCAP_SEQUENTIAL 0x00000400
** CAPI3REF: File Locking Levels
** SQLite uses one of these integer values as the second
** argument to calls it makes to the xLock() and xUnlock() methods
** of an [sqlite3_io_methods] object.
** CAPI3REF: Synchronization Type Flags
** When SQLite invokes the xSync() method of an
** [sqlite3_io_methods] object it uses a combination of
** these integer values as the second argument.
** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
** sync operation only needs to flush data to mass storage. Inode
** information need not be flushed. If the lower four bits of the flag
** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.
** If the lower four bits equal SQLITE_SYNC_FULL, that means
** to use Mac OS X style fullsync instead of fsync().
** Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags
** with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL
** settings. The [synchronous pragma] determines when calls to the
** xSync VFS method occur and applies uniformly across all platforms.
** The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how
** energetic or rigorous or forceful the sync operations are and
** only make a difference on Mac OSX for the default SQLite code.
** (Third-party VFS implementations might also make the distinction
** between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the
** operating systems natively supported by SQLite, only Mac OSX
** cares about the difference.)
#define SQLITE_SYNC_NORMAL 0x00002
#define SQLITE_SYNC_FULL 0x00003
#define SQLITE_SYNC_DATAONLY 0x00010
** CAPI3REF: OS Interface Open File Handle
** An [sqlite3_file] object represents an open file in the
** [sqlite3_vfs | OS interface layer]. Individual OS interface
** implementations will
** want to subclass this object by appending additional fields
** for their own use. The pMethods entry is a pointer to an
** [sqlite3_io_methods] object that defines methods for performing
** I/O operations on the open file.
typedef struct sqlite3_file sqlite3_file;
struct sqlite3_file {
const struct sqlite3_io_methods *pMethods; /* Methods for an open file */
** CAPI3REF: OS Interface File Virtual Methods Object
** Every file opened by the [sqlite3_vfs.xOpen] method populates an
** [sqlite3_file] object (or, more commonly, a subclass of the
** [sqlite3_file] object) with a pointer to an instance of this object.
** This object defines the methods used to perform various operations
** against the open file represented by the [sqlite3_file] object.
** If the [sqlite3_vfs.xOpen] method sets the sqlite3_file.pMethods element
** to a non-NULL pointer, then the sqlite3_io_methods.xClose method
** may be invoked even if the [sqlite3_vfs.xOpen] reported that it failed. The
** only way to prevent a call to xClose following a failed [sqlite3_vfs.xOpen]
** is for the [sqlite3_vfs.xOpen] to set the sqlite3_file.pMethods element
** to NULL.
** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
** [SQLITE_SYNC_FULL]. The first choice is the normal fsync().
** The second choice is a Mac OS X style fullsync. The [SQLITE_SYNC_DATAONLY]
** flag may be ORed in to indicate that only the data of the file
** and not its inode needs to be synced.
** The integer values to xLock() and xUnlock() are one of
** <ul>
** </ul>
** xLock() increases the lock. xUnlock() decreases the lock.
** The xCheckReservedLock() method checks whether any database connection,
** either in this process or in some other process, is holding a RESERVED,
** PENDING, or EXCLUSIVE lock on the file. It returns true
** if such a lock exists and false otherwise.
** The xFileControl() method is a generic interface that allows custom
** VFS implementations to directly control an open file using the
** [sqlite3_file_control()] interface. The second "op" argument is an
** integer opcode. The third argument is a generic pointer intended to
** point to a structure that may contain arguments or space in which to
** write return values. Potential uses for xFileControl() might be
** functions to enable blocking locks with timeouts, to change the
** locking strategy (for example to use dot-file locks), to inquire
** about the status of a lock, or to break stale locks. The SQLite
** core reserves all opcodes less than 100 for its own use.
** A [SQLITE_FCNTL_LOCKSTATE | list of opcodes] less than 100 is available.
** Applications that define a custom xFileControl method should use opcodes
** greater than 100 to avoid conflicts. VFS implementations should
** return [SQLITE_NOTFOUND] for file control opcodes that they do not
** recognize.
** The xSectorSize() method returns the sector size of the
** device that underlies the file. The sector size is the
** minimum write that can be performed without disturbing
** other bytes in the file. The xDeviceCharacteristics()
** method returns a bit vector describing behaviors of the
** underlying device:
** <ul>
** </ul>
** The SQLITE_IOCAP_ATOMIC property means that all writes of
** any size are atomic. The SQLITE_IOCAP_ATOMICnnn values
** mean that writes of blocks that are nnn bytes in size and
** are aligned to an address which is an integer multiple of
** nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means
** that when data is appended to a file, the data is appended
** first then the size of the file is extended, never the other
** way around. The SQLITE_IOCAP_SEQUENTIAL property means that
** information is written to disk in the same order as calls
** to xWrite().
** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
** in the unread portions of the buffer with zeros. A VFS that
** fails to zero-fill short reads might seem to work. However,
** failure to zero-fill short reads will eventually lead to
** database corruption.
typedef struct sqlite3_io_methods sqlite3_io_methods;
struct sqlite3_io_methods {
int iVersion;
int (*xClose)(sqlite3_file*);
int (*xRead)(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
int (*xWrite)(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst);
int (*xTruncate)(sqlite3_file*, sqlite3_int64 size);
int (*xSync)(sqlite3_file*, int flags);
int (*xFileSize)(sqlite3_file*, sqlite3_int64 *pSize);
int (*xLock)(sqlite3_file*, int);
int (*xUnlock)(sqlite3_file*, int);
int (*xCheckReservedLock)(sqlite3_file*, int *pResOut);
int (*xFileControl)(sqlite3_file*, int op, void *pArg);
int (*xSectorSize)(sqlite3_file*);
int (*xDeviceCharacteristics)(sqlite3_file*);
/* Methods above are valid for version 1 */
int (*xShmMap)(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
int (*xShmLock)(sqlite3_file*, int offset, int n, int flags);
void (*xShmBarrier)(sqlite3_file*);
int (*xShmUnmap)(sqlite3_file*, int deleteFlag);
/* Methods above are valid for version 2 */
int (*xFetch)(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
int (*xUnfetch)(sqlite3_file*, sqlite3_int64 iOfst, void *p);
/* Methods above are valid for version 3 */
/* Additional methods may be added in future releases */
** CAPI3REF: Standard File Control Opcodes
** These integer constants are opcodes for the xFileControl method
** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
** interface.
** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging. This
** opcode causes the xFileControl method to write the current state of
** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
** into an integer that the pArg argument points to. This capability
** is used during testing and only needs to be supported when SQLITE_TEST
** is defined.
** <ul>
** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
** layer a hint of how large the database file will grow to be during the
** current transaction. This hint is not guaranteed to be accurate but it
** is often close. The underlying VFS might choose to preallocate database
** file space based on this hint in order to help writes to the database
** file run faster.
** The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS
** extends and truncates the database file in chunks of a size specified
** by the user. The fourth argument to [sqlite3_file_control()] should
** point to an integer (type int) containing the new chunk-size to use
** for the nominated database. Allocating database file space in large
** chunks (say 1MB at a time), may reduce file-system fragmentation and
** improve performance on some systems.
** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
** to the [sqlite3_file] object associated with a particular database
** connection. See the [sqlite3_file_control()] documentation for
** additional information.
** ^(The [SQLITE_FCNTL_SYNC_OMITTED] opcode is generated internally by
** SQLite and sent to all VFSes in place of a call to the xSync method
** when the database connection has [PRAGMA synchronous] set to OFF.)^
** Some specialized VFSes need this signal in order to operate correctly
** when [PRAGMA synchronous | PRAGMA synchronous=OFF] is set, but most
** VFSes do not need this signal and should silently ignore this opcode.
** Applications should not call [sqlite3_file_control()] with this
** opcode as doing so may disrupt the operation of the specialized VFSes
** that do require it.
** ^The [SQLITE_FCNTL_WIN32_AV_RETRY] opcode is used to configure automatic
** retry counts and intervals for certain disk I/O operations for the
** windows [VFS] in order to provide robustness in the presence of
** anti-virus programs. By default, the windows VFS will retry file read,
** file write, and file delete operations up to 10 times, with a delay
** of 25 milliseconds before the first retry and with the delay increasing
** by an additional 25 milliseconds with each subsequent retry. This
** opcode allows these two values (10 retries and 25 milliseconds of delay)
** to be adjusted. The values are changed for all database connections
** within the same process. The argument is a pointer to an array of two
** integers where the first integer i the new retry count and the second
** integer is the delay. If either integer is negative, then the setting
** is not changed but instead the prior value of that setting is written
** into the array entry, allowing the current retry settings to be
** interrogated. The zDbName parameter is ignored.
** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the
** persistent [WAL | Write Ahead Log] setting. By default, the auxiliary
** write ahead log and shared memory files used for transaction control
** are automatically deleted when the latest connection to the database
** closes. Setting persistent WAL mode causes those files to persist after
** close. Persisting the files is useful when other processes that do not
** have write permission on the directory containing the database file want
** to read the database file, as the WAL and shared memory files must exist
** in order for the database to be readable. The fourth parameter to
** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
** WAL mode. If the integer is -1, then it is overwritten with the current
** WAL persistence setting.
** ^The [SQLITE_FCNTL_POWERSAFE_OVERWRITE] opcode is used to set or query the
** persistent "powersafe-overwrite" or "PSOW" setting. The PSOW setting
** determines the [SQLITE_IOCAP_POWERSAFE_OVERWRITE] bit of the
** xDeviceCharacteristics methods. The fourth parameter to
** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
** That integer is 0 to disable zero-damage mode or 1 to enable zero-damage
** mode. If the integer is -1, then it is overwritten with the current
** zero-damage mode setting.
** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
** a write transaction to indicate that, unless it is rolled back for some
** reason, the entire database file will be overwritten by the current
** transaction. This is used by VACUUM operations.
** ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of
** all [VFSes] in the VFS stack. The names are of all VFS shims and the
** final bottom-level VFS are written into memory obtained from
** [sqlite3_malloc()] and the result is stored in the char* variable
** that the fourth parameter of [sqlite3_file_control()] points to.
** The caller is responsible for freeing the memory when done. As with
** all file-control actions, there is no guarantee that this will actually
** do anything. Callers should initialize the char* variable to a NULL
** pointer in case this file-control is not implemented. This file-control
** is intended for diagnostic use only.
** ^Whenever a [PRAGMA] statement is parsed, an [SQLITE_FCNTL_PRAGMA]
** file control is sent to the open [sqlite3_file] object corresponding
** to the database file to which the pragma statement refers. ^The argument
** to the [SQLITE_FCNTL_PRAGMA] file control is an array of
** pointers to strings (char**) in which the second element of the array
** is the name of the pragma and the third element is the argument to the
** pragma or NULL if the pragma has no argument. ^The handler for an
** [SQLITE_FCNTL_PRAGMA] file control can optionally make the first element
** of the char** argument point to a string obtained from [sqlite3_mprintf()]
** or the equivalent and that string will become the result of the pragma or
** the error message if the pragma fails. ^If the
** [SQLITE_FCNTL_PRAGMA] file control returns [SQLITE_NOTFOUND], then normal
** [PRAGMA] processing continues. ^If the [SQLITE_FCNTL_PRAGMA]
** file control returns [SQLITE_OK], then the parser assumes that the
** VFS has handled the PRAGMA itself and the parser generates a no-op
** prepared statement. ^If the [SQLITE_FCNTL_PRAGMA] file control returns
** any result code other than [SQLITE_OK] or [SQLITE_NOTFOUND], that means
** that the VFS encountered an error while handling the [PRAGMA] and the
** compilation of the PRAGMA fails with an error. ^The [SQLITE_FCNTL_PRAGMA]
** file control occurs at the beginning of pragma statement analysis and so
** it is able to override built-in [PRAGMA] statements.
** file-control may be invoked by SQLite on the database file handle
** shortly after it is opened in order to provide a custom VFS with access
** to the connections busy-handler callback. The argument is of type (void **)
** - an array of two (void *) values. The first (void *) actually points
** to a function of type (int (*)(void *)). In order to invoke the connections
** busy-handler, this function should be invoked with the second (void *) in
** the array as the only argument. If it returns non-zero, then the operation
** should be retried. If it returns zero, the custom VFS should abandon the
** current operation.
** ^Application can invoke the [SQLITE_FCNTL_TEMPFILENAME] file-control
** to have SQLite generate a
** temporary filename using the same algorithm that is followed to generate
** temporary filenames for TEMP tables and other internal uses. The
** argument should be a char** which will be filled with the filename
** written into memory obtained from [sqlite3_malloc()]. The caller should
** invoke [sqlite3_free()] on the result to avoid a memory leak.
** The [SQLITE_FCNTL_MMAP_SIZE] file control is used to query or set the
** maximum number of bytes that will be used for memory-mapped I/O.
** The argument is a pointer to a value of type sqlite3_int64 that
** is an advisory maximum number of bytes in the file to memory map. The
** pointer is overwritten with the old value. The limit is not changed if
** the value originally pointed to is negative, and so the current limit
** can be queried by passing in a pointer to a negative number. This
** file-control is used internally to implement [PRAGMA mmap_size].
** The [SQLITE_FCNTL_TRACE] file control provides advisory information
** to the VFS about what the higher layers of the SQLite stack are doing.
** This file control is used by some VFS activity tracing [shims].
** The argument is a zero-terminated string. Higher layers in the
** SQLite stack may generate instances of this file control if
** the [SQLITE_USE_FCNTL_TRACE] compile-time option is enabled.
** </ul>
** CAPI3REF: Mutex Handle
** The mutex module within SQLite defines [sqlite3_mutex] to be an
** abstract type for a mutex object. The SQLite core never looks
** at the internal representation of an [sqlite3_mutex]. It only
** deals with pointers to the [sqlite3_mutex] object.
** Mutexes are created using [sqlite3_mutex_alloc()].
typedef struct sqlite3_mutex sqlite3_mutex;
** CAPI3REF: OS Interface Object
** An instance of the sqlite3_vfs object defines the interface between
** the SQLite core and the underlying operating system. The "vfs"
** in the name of the object stands for "virtual file system". See
** the [VFS | VFS documentation] for further information.
** The value of the iVersion field is initially 1 but may be larger in
** future versions of SQLite. Additional fields may be appended to this
** object when the iVersion value is increased. Note that the structure
** of the sqlite3_vfs object changes in the transaction between
** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not
** modified.
** The szOsFile field is the size of the subclassed [sqlite3_file]
** structure used by this VFS. mxPathname is the maximum length of
** a pathname in this VFS.
** Registered sqlite3_vfs objects are kept on a linked list formed by
** the pNext pointer. The [sqlite3_vfs_register()]
** and [sqlite3_vfs_unregister()] interfaces manage this list
** in a thread-safe way. The [sqlite3_vfs_find()] interface
** searches the list. Neither the application code nor the VFS
** implementation should use the pNext pointer.
** The pNext field is the only field in the sqlite3_vfs
** structure that SQLite will ever modify. SQLite will only access
** or modify this field while holding a particular static mutex.
** The application should never modify anything within the sqlite3_vfs
** object once the object has been registered.
** The zName field holds the name of the VFS module. The name must
** be unique across all VFS modules.
** [[sqlite3_vfs.xOpen]]
** ^SQLite guarantees that the zFilename parameter to xOpen
** is either a NULL pointer or string obtained
** from xFullPathname() with an optional suffix added.
** ^If a suffix is added to the zFilename parameter, it will
** consist of a single "-" character followed by no more than
** 11 alphanumeric and/or "-" characters.
** ^SQLite further guarantees that
** the string will be valid and unchanged until xClose() is
** called. Because of the previous sentence,
** the [sqlite3_file] can safely store a pointer to the
** filename if it needs to remember the filename for some reason.
** If the zFilename parameter to xOpen is a NULL pointer then xOpen
** must invent its own temporary name for the file. ^Whenever the
** xFilename parameter is NULL it will also be the case that the
** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
** The flags argument to xOpen() includes all bits set in
** the flags argument to [sqlite3_open_v2()]. Or if [sqlite3_open()]
** or [sqlite3_open16()] is used, then flags includes at least
** If xOpen() opens a file read-only then it sets *pOutFlags to
** include [SQLITE_OPEN_READONLY]. Other bits in *pOutFlags may be set.
** ^(SQLite will also add one of the following flags to the xOpen()
** call, depending on the object being opened:
** <ul>
** </ul>)^
** The file I/O implementation can use the object type flags to
** change the way it deals with files. For example, an application
** that does not care about crash recovery or rollback might make
** the open of a journal file a no-op. Writes to this journal would
** also be no-ops, and any attempt to read the journal would return
** SQLITE_IOERR. Or the implementation might recognize that a database
** file will be doing page-aligned sector reads and writes in a random
** order and set up its I/O subsystem accordingly.
** SQLite might also add one of the following flags to the xOpen method:
** <ul>
** </ul>
** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
** deleted when it is closed. ^The [SQLITE_OPEN_DELETEONCLOSE]
** will be set for TEMP databases and their journals, transient
** databases, and subjournals.
** ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction
** with the [SQLITE_OPEN_CREATE] flag, which are both directly
** analogous to the O_EXCL and O_CREAT flags of the POSIX open()
** API. The SQLITE_OPEN_EXCLUSIVE flag, when paired with the
** SQLITE_OPEN_CREATE, is used to indicate that file should always
** be created, and that it is an error if it already exists.
** It is <i>not</i> used to indicate the file should be opened
** for exclusive access.
** ^At least szOsFile bytes of memory are allocated by SQLite
** to hold the [sqlite3_file] structure passed as the third
** argument to xOpen. The xOpen method does not have to
** allocate the structure; it should just fill it in. Note that
** the xOpen method must set the sqlite3_file.pMethods to either
** a valid [sqlite3_io_methods] object or to NULL. xOpen must do
** this even if the open fails. SQLite expects that the sqlite3_file.pMethods
** element will be valid after xOpen returns regardless of the success
** or failure of the xOpen call.
** [[sqlite3_vfs.xAccess]]
** ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
** to test whether a file is at least readable. The file can be a
** directory.
** ^SQLite will always allocate at least mxPathname+1 bytes for the
** output buffer xFullPathname. The exact size of the output buffer
** is also passed as a parameter to both methods. If the output buffer
** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
** handled as a fatal error by SQLite, vfs implementations should endeavor
** to prevent this by setting mxPathname to a sufficiently large value.
** The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64()
** interfaces are not strictly a part of the filesystem, but they are
** included in the VFS structure for completeness.
** The xRandomness() function attempts to return nBytes bytes
** of good-quality randomness into zOut. The return value is
** the actual number of bytes of randomness obtained.
** The xSleep() method causes the calling thread to sleep for at
** least the number of microseconds given. ^The xCurrentTime()
** method returns a Julian Day Number for the current date and time as
** a floating point value.
** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
** Day Number multiplied by 86400000 (the number of milliseconds in
** a 24-hour day).
** ^SQLite will use the xCurrentTimeInt64() method to get the current
** date and time if that method is available (if iVersion is 2 or
** greater and the function pointer is not NULL) and will fall back
** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
** are not used by the SQLite core. These optional interfaces are provided
** by some VFSes to facilitate testing of the VFS code. By overriding
** system calls with functions under its control, a test program can
** simulate faults and error conditions that would otherwise be difficult
** or impossible to induce. The set of system calls that can be overridden
** varies from one VFS to another, and from one version of the same VFS to the
** next. Applications that use these interfaces must be prepared for any
** or all of these interfaces to be NULL or for their behavior to change
** from one release to the next. Applications must not attempt to access
** any of these methods if the iVersion of the VFS is less than 3.
typedef struct sqlite3_vfs sqlite3_vfs;
typedef void (*sqlite3_syscall_ptr)(void);
struct sqlite3_vfs {
int iVersion; /* Structure version number (currently 3) */
int szOsFile; /* Size of subclassed sqlite3_file */
int mxPathname; /* Maximum file pathname length */
sqlite3_vfs *pNext; /* Next registered VFS */
const char *zName; /* Name of this virtual file system */
void *pAppData; /* Pointer to application-specific data */
int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
int flags, int *pOutFlags);
int (*xDelete)(sqlite3_vfs*, const char *zName, int syncDir);
int (*xAccess)(sqlite3_vfs*, const char *zName, int flags, int *pResOut);
int (*xFullPathname)(sqlite3_vfs*, const char *zName, int nOut, char *zOut);
void *(*xDlOpen)(sqlite3_vfs*, const char *zFilename);
void (*xDlError)(sqlite3_vfs*, int nByte, char *zErrMsg);
void (*(*xDlSym)(sqlite3_vfs*,void*, const char *zSymbol))(void);
void (*xDlClose)(sqlite3_vfs*, void*);
int (*xRandomness)(sqlite3_vfs*, int nByte, char *zOut);
int (*xSleep)(sqlite3_vfs*, int microseconds);
int (*xCurrentTime)(sqlite3_vfs*, double*);
int (*xGetLastError)(sqlite3_vfs*, int, char *);
** The methods above are in version 1 of the sqlite_vfs object
** definition. Those that follow are added in version 2 or later
int (*xCurrentTimeInt64)(sqlite3_vfs*, sqlite3_int64*);
** The methods above are in versions 1 and 2 of the sqlite_vfs object.
** Those below are for version 3 and greater.
int (*xSetSystemCall)(sqlite3_vfs*, const char *zName, sqlite3_syscall_ptr);
sqlite3_syscall_ptr (*xGetSystemCall)(sqlite3_vfs*, const char *zName);
const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
** The methods above are in versions 1 through 3 of the sqlite_vfs object.
** New fields may be appended in figure versions. The iVersion
** value will increment whenever this happens.
** CAPI3REF: Flags for the xAccess VFS method
** These integer constants can be used as the third parameter to
** the xAccess method of an [sqlite3_vfs] object. They determine
** what kind of permissions the xAccess method is looking for.
** With SQLITE_ACCESS_EXISTS, the xAccess method
** simply checks whether the file exists.
** With SQLITE_ACCESS_READWRITE, the xAccess method
** checks whether the named directory is both readable and writable
** (in other words, if files can be added, removed, and renamed within
** the directory).
** The SQLITE_ACCESS_READWRITE constant is currently used only by the
** [temp_store_directory pragma], though this could change in a future
** release of SQLite.
** With SQLITE_ACCESS_READ, the xAccess method
** checks whether the file is readable. The SQLITE_ACCESS_READ constant is
** currently unused, though it might be used in a future release of
** SQLite.
#define SQLITE_ACCESS_READWRITE 1 /* Used by PRAGMA temp_store_directory */
#define SQLITE_ACCESS_READ 2 /* Unused */
** CAPI3REF: Flags for the xShmLock VFS method
** These integer constants define the various locking operations
** allowed by the xShmLock method of [sqlite3_io_methods]. The
** following are the only legal combinations of flags to the
** xShmLock method:
** <ul>
** </ul>
** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
** was given no the corresponding lock.
** The xShmLock method can transition between unlocked and SHARED or
** between unlocked and EXCLUSIVE. It cannot transition between SHARED
** CAPI3REF: Maximum xShmLock index
** The xShmLock method on [sqlite3_io_methods] may use values
** between 0 and this upper bound as its "offset" argument.
** The SQLite core will never attempt to acquire or release a
** lock outside of this range
** CAPI3REF: Initialize The SQLite Library
** ^The sqlite3_initialize() routine initializes the
** SQLite library. ^The sqlite3_shutdown() routine
** deallocates any resources that were allocated by sqlite3_initialize().
** These routines are designed to aid in process initialization and
** shutdown on embedded systems. Workstation applications using
** SQLite normally do not need to invoke either of these routines.
** A call to sqlite3_initialize() is an "effective" call if it is
** the first time sqlite3_initialize() is invoked during the lifetime of
** the process, or if it is the first time sqlite3_initialize() is invoked
** following a call to sqlite3_shutdown(). ^(Only an effective call
** of sqlite3_initialize() does any initialization. All other calls
** are harmless no-ops.)^
** A call to sqlite3_shutdown() is an "effective" call if it is the first
** call to sqlite3_shutdown() since the last sqlite3_initialize(). ^(Only
** an effective call to sqlite3_shutdown() does any deinitialization.
** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^
** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()
** is not. The sqlite3_shutdown() interface must only be called from a
** single thread. All open [database connections] must be closed and all
** other SQLite resources must be deallocated prior to invoking
** sqlite3_shutdown().
** Among other things, ^sqlite3_initialize() will invoke
** sqlite3_os_init(). Similarly, ^sqlite3_shutdown()
** will invoke sqlite3_os_end().
** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.
** ^If for some reason, sqlite3_initialize() is unable to initialize
** the library (perhaps it is unable to allocate a needed resource such
** as a mutex) it returns an [error code] other than [SQLITE_OK].
** ^The sqlite3_initialize() routine is called internally by many other
** SQLite interfaces so that an application usually does not need to
** invoke sqlite3_initialize() directly. For example, [sqlite3_open()]
** calls sqlite3_initialize() so the SQLite library will be automatically
** initialized when [sqlite3_open()] is called if it has not be initialized
** already. ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
** compile-time option, then the automatic calls to sqlite3_initialize()
** are omitted and the application must call sqlite3_initialize() directly
** prior to using any other SQLite interface. For maximum portability,
** it is recommended that applications always invoke sqlite3_initialize()
** directly prior to using any other SQLite interface. Future releases
** of SQLite may require this. In other words, the behavior exhibited
** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
** default behavior in some future release of SQLite.
** The sqlite3_os_init() routine does operating-system specific
** initialization of the SQLite library. The sqlite3_os_end()
** routine undoes the effect of sqlite3_os_init(). Typical tasks
** performed by these routines include allocation or deallocation
** of static resources, initialization of global variables,
** setting up a default [sqlite3_vfs] module, or setting up
** a default configuration using [sqlite3_config()].
** The application should never invoke either sqlite3_os_init()
** or sqlite3_os_end() directly. The application should only invoke
** sqlite3_initialize() and sqlite3_shutdown(). The sqlite3_os_init()
** interface is called automatically by sqlite3_initialize() and
** sqlite3_os_end() is called by sqlite3_shutdown(). Appropriate
** implementations for sqlite3_os_init() and sqlite3_os_end()
** are built into SQLite when it is compiled for Unix, Windows, or OS/2.
** When [custom builds | built for other platforms]
** (using the [SQLITE_OS_OTHER=1] compile-time
** option) the application must supply a suitable implementation for
** sqlite3_os_init() and sqlite3_os_end(). An application-supplied
** implementation of sqlite3_os_init() or sqlite3_os_end()
** must return [SQLITE_OK] on success and some other [error code] upon
** failure.
SQLITE_API int sqlite3_initialize(void);
SQLITE_API int sqlite3_shutdown(void);
SQLITE_API int sqlite3_os_init(void);
SQLITE_API int sqlite3_os_end(void);
** CAPI3REF: Configuring The SQLite Library
** The sqlite3_config() interface is used to make global configuration
** changes to SQLite in order to tune SQLite to the specific needs of
** the application. The default configuration is recommended for most
** applications and so this routine is usually not necessary. It is
** provided to support rare applications with unusual needs.
** The sqlite3_config() interface is not threadsafe. The application
** must insure that no other SQLite interfaces are invoked by other
** threads while sqlite3_config() is running. Furthermore, sqlite3_config()
** may only be invoked prior to library initialization using
** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.
** Note, however, that ^sqlite3_config() can be called as part of the
** implementation of an application-defined [sqlite3_os_init()].
** The first argument to sqlite3_config() is an integer
** [configuration option] that determines
** what property of SQLite is to be configured. Subsequent arguments
** vary depending on the [configuration option]
** in the first argument.
** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
** ^If the option is unknown or SQLite is unable to set the option
** then this routine returns a non-zero [error code].
SQLITE_API int sqlite3_config(int, ...);
** CAPI3REF: Configure database connections
** The sqlite3_db_config() interface is used to make configuration
** changes to a [database connection]. The interface is similar to
** [sqlite3_config()] except that the changes apply to a single
** [database connection] (specified in the first argument).
** The second argument to sqlite3_db_config(D,V,...) is the
** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code
** that indicates what aspect of the [database connection] is being configured.
** Subsequent arguments vary depending on the configuration verb.
** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
** the call is considered successful.
SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);
** CAPI3REF: Memory Allocation Routines
** An instance of this object defines the interface between SQLite
** and low-level memory allocation routines.
** This object is used in only one place in the SQLite interface.
** A pointer to an instance of this object is the argument to
** [sqlite3_config()] when the configuration option is
** By creating an instance of this object
** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])
** during configuration, an application can specify an alternative
** memory allocation subsystem for SQLite to use for all of its
** dynamic memory needs.
** Note that SQLite comes with several [built-in memory allocators]
** that are perfectly adequate for the overwhelming majority of applications
** and that this object is only useful to a tiny minority of applications
** with specialized memory allocation requirements. This object is
** also used during testing of SQLite in order to specify an alternative
** memory allocator that simulates memory out-of-memory conditions in
** order to verify that SQLite recovers gracefully from such
** conditions.
** The xMalloc, xRealloc, and xFree methods must work like the
** malloc(), realloc() and free() functions from the standard C library.
** ^SQLite guarantees that the second argument to
** xRealloc is always a value returned by a prior call to xRoundup.
** xSize should return the allocated size of a memory allocation
** previously obtained from xMalloc or xRealloc. The allocated size
** is always at least as big as the requested size but may be larger.
** The xRoundup method returns what would be the allocated size of
** a memory allocation given a particular requested size. Most memory
** allocators round up memory allocations at least to the next multiple
** of 8. Some allocators round up to a larger multiple or to a power of 2.
** Every memory allocation request coming in through [sqlite3_malloc()]
** or [sqlite3_realloc()] first calls xRoundup. If xRoundup returns 0,
** that causes the corresponding memory allocation to fail.
** The xInit method initializes the memory allocator. For example,
** it might allocate any require mutexes or initialize internal data
** structures. The xShutdown method is invoked (indirectly) by
** [sqlite3_shutdown()] and should deallocate any resources acquired
** by xInit. The pAppData pointer is used as the only parameter to
** xInit and xShutdown.
** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes
** the xInit method, so the xInit method need not be threadsafe. The
** xShutdown method is only called from [sqlite3_shutdown()] so it does
** not need to be threadsafe either. For all other methods, SQLite
** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the
** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which
** it is by default) and so the methods are automatically serialized.
** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other
** methods must be threadsafe or else make their own arrangements for
** serialization.
** SQLite will never invoke xInit() more than once without an intervening
** call to xShutdown().
typedef struct sqlite3_mem_methods sqlite3_mem_methods;
struct sqlite3_mem_methods {
void *(*xMalloc)(int); /* Memory allocation function */
void (*xFree)(void*); /* Free a prior allocation */
void *(*xRealloc)(void*,int); /* Resize an allocation */
int (*xSize)(void*); /* Return the size of an allocation */
int (*xRoundup)(int); /* Round up request size to allocation size */
int (*xInit)(void*); /* Initialize the memory allocator */
void (*xShutdown)(void*); /* Deinitialize the memory allocator */
void *pAppData; /* Argument to xInit() and xShutdown() */
** CAPI3REF: Configuration Options
** KEYWORDS: {configuration option}
** These constants are the available integer configuration options that
** can be passed as the first argument to the [sqlite3_config()] interface.
** New configuration options may be added in future releases of SQLite.
** Existing configuration options might be discontinued. Applications
** should check the return code from [sqlite3_config()] to make sure that
** the call worked. The [sqlite3_config()] interface will return a
** non-zero [error code] if a discontinued or unsupported configuration option
** is invoked.
** <dl>
** <dd>There are no arguments to this option. ^This option sets the
** [threading mode] to Single-thread. In other words, it disables
** all mutexing and puts SQLite into a mode where it can only be used
** by a single thread. ^If SQLite is compiled with
** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
** it is not possible to change the [threading mode] from its default
** value of Single-thread and so [sqlite3_config()] will return
** configuration option.</dd>
** <dd>There are no arguments to this option. ^This option sets the
** [threading mode] to Multi-thread. In other words, it disables
** mutexing on [database connection] and [prepared statement] objects.
** The application is responsible for serializing access to
** [database connections] and [prepared statements]. But other mutexes
** are enabled so that SQLite will be safe to use in a multi-threaded
** environment as long as no two threads attempt to use the same
** [database connection] at the same time. ^If SQLite is compiled with
** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
** it is not possible to set the Multi-thread [threading mode] and
** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>
** <dd>There are no arguments to this option. ^This option sets the
** [threading mode] to Serialized. In other words, this option enables
** all mutexes including the recursive
** mutexes on [database connection] and [prepared statement] objects.
** In this mode (which is the default when SQLite is compiled with
** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
** to [database connections] and [prepared statements] so that the
** application is free to use the same [database connection] or the
** same [prepared statement] in different threads at the same time.
** ^If SQLite is compiled with
** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
** it is not possible to set the Serialized [threading mode] and
** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
** SQLITE_CONFIG_SERIALIZED configuration option.</dd>
** <dd> ^(This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mem_methods] structure. The argument specifies
** alternative low-level memory allocation routines to be used in place of
** the memory allocation routines built into SQLite.)^ ^SQLite makes
** its own private copy of the content of the [sqlite3_mem_methods] structure
** before the [sqlite3_config()] call returns.</dd>
** <dd> ^(This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mem_methods] structure. The [sqlite3_mem_methods]
** structure is filled with the currently defined memory allocation routines.)^
** This option can be used to overload the default memory allocation
** routines with a wrapper that simulations memory allocation failure or
** tracks memory usage, for example. </dd>
** <dd> ^This option takes single argument of type int, interpreted as a
** boolean, which enables or disables the collection of memory allocation
** statistics. ^(When memory allocation statistics are disabled, the
** following SQLite interfaces become non-operational:
** <ul>
** <li> [sqlite3_memory_used()]
** <li> [sqlite3_memory_highwater()]
** <li> [sqlite3_soft_heap_limit64()]
** <li> [sqlite3_status()]
** </ul>)^
** ^Memory allocation statistics are enabled by default unless SQLite is
** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
** allocation statistics are disabled by default.
** </dd>
** <dd> ^This option specifies a static memory buffer that SQLite can use for
** scratch memory. There are three arguments: A pointer an 8-byte
** aligned memory buffer from which the scratch allocations will be
** drawn, the size of each scratch allocation (sz),
** and the maximum number of scratch allocations (N). The sz
** argument must be a multiple of 16.
** The first argument must be a pointer to an 8-byte aligned buffer
** of at least sz*N bytes of memory.
** ^SQLite will use no more than two scratch buffers per thread. So
** N should be set to twice the expected maximum number of threads.
** ^SQLite will never require a scratch buffer that is more than 6
** times the database page size. ^If SQLite needs needs additional
** scratch memory beyond what is provided by this configuration option, then
** [sqlite3_malloc()] will be used to obtain the memory needed.</dd>
** <dd> ^This option specifies a static memory buffer that SQLite can use for
** the database page cache with the default page cache implementation.
** This configuration should not be used if an application-define page
** cache implementation is loaded using the SQLITE_CONFIG_PCACHE2 option.
** There are three arguments to this option: A pointer to 8-byte aligned
** memory, the size of each page buffer (sz), and the number of pages (N).
** The sz argument should be the size of the largest database page
** (a power of two between 512 and 32768) plus a little extra for each
** page header. ^The page header size is 20 to 40 bytes depending on
** the host architecture. ^It is harmless, apart from the wasted memory,
** to make sz a little too large. The first
** argument should point to an allocation of at least sz*N bytes of memory.
** ^SQLite will use the memory provided by the first argument to satisfy its
** memory needs for the first N pages that it adds to cache. ^If additional
** page cache memory is needed beyond what is provided by this option, then
** SQLite goes to [sqlite3_malloc()] for the additional storage space.
** The pointer in the first argument must
** be aligned to an 8-byte boundary or subsequent behavior of SQLite
** will be undefined.</dd>
** <dd> ^This option specifies a static memory buffer that SQLite will use
** for all of its dynamic memory allocation needs beyond those provided
** There are three arguments: An 8-byte aligned pointer to the memory,
** the number of bytes in the memory buffer, and the minimum allocation size.
** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
** to using its default memory allocator (the system malloc() implementation),
** undoing any prior invocation of [SQLITE_CONFIG_MALLOC]. ^If the
** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
** allocator is engaged to handle all of SQLites memory allocation needs.
** The first pointer (the memory pointer) must be aligned to an 8-byte
** boundary or subsequent behavior of SQLite will be undefined.
** The minimum allocation size is capped at 2**12. Reasonable values
** for the minimum allocation size are 2**5 through 2**8.</dd>
** <dd> ^(This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mutex_methods] structure. The argument specifies
** alternative low-level mutex routines to be used in place
** the mutex routines built into SQLite.)^ ^SQLite makes a copy of the
** content of the [sqlite3_mutex_methods] structure before the call to
** [sqlite3_config()] returns. ^If SQLite is compiled with
** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
** the entire mutexing subsystem is omitted from the build and hence calls to
** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
** return [SQLITE_ERROR].</dd>
** <dd> ^(This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mutex_methods] structure. The
** [sqlite3_mutex_methods]
** structure is filled with the currently defined mutex routines.)^
** This option can be used to overload the default mutex allocation
** routines with a wrapper used to track mutex usage for performance
** profiling or testing, for example. ^If SQLite is compiled with
** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
** the entire mutexing subsystem is omitted from the build and hence calls to
** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will
** return [SQLITE_ERROR].</dd>
** <dd> ^(This option takes two arguments that determine the default
** memory allocation for the lookaside memory allocator on each
** [database connection]. The first argument is the
** size of each lookaside buffer slot and the second is the number of
** slots allocated to each database connection.)^ ^(This option sets the
** <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]
** verb to [sqlite3_db_config()] can be used to change the lookaside
** configuration on individual connections.)^ </dd>
** <dd> ^(This option takes a single argument which is a pointer to
** an [sqlite3_pcache_methods2] object. This object specifies the interface
** to a custom page cache implementation.)^ ^SQLite makes a copy of the
** object and uses it for page cache memory allocations.</dd>
** <dd> ^(This option takes a single argument which is a pointer to an
** [sqlite3_pcache_methods2] object. SQLite copies of the current
** page cache implementation into that object.)^ </dd>
** <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite
** global [error log].
** (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
** function with a call signature of void(*)(void*,int,const char*),
** and a pointer to void. ^If the function pointer is not NULL, it is
** invoked by [sqlite3_log()] to process each logging event. ^If the
** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
** passed through as the first parameter to the application-defined logger
** function whenever that function is invoked. ^The second parameter to
** the logger function is a copy of the first parameter to the corresponding
** [sqlite3_log()] call and is intended to be a [result code] or an
** [extended result code]. ^The third parameter passed to the logger is
** log message after formatting via [sqlite3_snprintf()].
** The SQLite logging interface is not reentrant; the logger function
** supplied by the application must not invoke any SQLite interface.
** In a multi-threaded application, the application-defined logger
** function must be threadsafe. </dd>
** <dd>^(This option takes a single argument of type int. If non-zero, then
** URI handling is globally enabled. If the parameter is zero, then URI handling
** is globally disabled.)^ ^If URI handling is globally enabled, all filenames
** passed to [sqlite3_open()], [sqlite3_open_v2()], [sqlite3_open16()] or
** specified as part of [ATTACH] commands are interpreted as URIs, regardless
** of whether or not the [SQLITE_OPEN_URI] flag is set when the database
** connection is opened. ^If it is globally disabled, filenames are
** only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the
** database connection is opened. ^(By default, URI handling is globally
** disabled. The default value may be changed by compiling with the
** [SQLITE_USE_URI] symbol defined.)^
** <dd>^This option takes a single integer argument which is interpreted as
** a boolean in order to enable or disable the use of covering indices for
** full table scans in the query optimizer. ^The default setting is determined
** by the [SQLITE_ALLOW_COVERING_INDEX_SCAN] compile-time option, or is "on"
** if that compile-time option is omitted.
** The ability to disable the use of covering indices for full table scans
** is because some incorrectly coded legacy applications might malfunction
** when the optimization is enabled. Providing the ability to
** disable the optimization allows the older, buggy application code to work
** without change even with newer versions of SQLite.
** <dd> These options are obsolete and should not be used by new code.
** They are retained for backwards compatibility but are now no-ops.
** </dd>
** <dd>This option is only available if sqlite is compiled with the
** [SQLITE_ENABLE_SQLLOG] pre-processor macro defined. The first argument should
** be a pointer to a function of type void(*)(void*,sqlite3*,const char*, int).
** The second should be of type (void*). The callback is invoked by the library
** in three separate circumstances, identified by the value passed as the
** fourth parameter. If the fourth parameter is 0, then the database connection
** passed as the second argument has just been opened. The third argument
** points to a buffer containing the name of the main database file. If the
** fourth parameter is 1, then the SQL statement that the third parameter
** points to has just been executed. Or, if the fourth parameter is 2, then
** the connection being passed as the second parameter is being closed. The
** third parameter is passed NULL In this case. An example of using this
** configuration option can be seen in the "test_sqllog.c" source file in
** the canonical SQLite source tree.</dd>
** <dd>^SQLITE_CONFIG_MMAP_SIZE takes two 64-bit integer (sqlite3_int64) values
** that are the default mmap size limit (the default setting for
** [PRAGMA mmap_size]) and the maximum allowed mmap size limit.
** ^The default setting can be overridden by each database connection using
** either the [PRAGMA mmap_size] command, or by using the
** [SQLITE_FCNTL_MMAP_SIZE] file control. ^(The maximum allowed mmap size
** cannot be changed at run-time. Nor may the maximum allowed mmap size
** exceed the compile-time maximum mmap size set by the
** [SQLITE_MAX_MMAP_SIZE] compile-time option.)^
** ^If either argument to this option is negative, then that argument is
** changed to its compile-time default.
** <dd>^This option is only available if SQLite is compiled for Windows
** with the [SQLITE_WIN32_MALLOC] pre-processor macro defined.
** SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value
** that specifies the maximum size of the created heap.
** </dl>
#define SQLITE_CONFIG_SERIALIZED 3 /* nil */
#define SQLITE_CONFIG_MALLOC 4 /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_GETMALLOC 5 /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_SCRATCH 6 /* void*, int sz, int N */
#define SQLITE_CONFIG_PAGECACHE 7 /* void*, int sz, int N */
#define SQLITE_CONFIG_HEAP 8 /* void*, int nByte, int min */
#define SQLITE_CONFIG_MEMSTATUS 9 /* boolean */
#define SQLITE_CONFIG_MUTEX 10 /* sqlite3_mutex_methods* */
#define SQLITE_CONFIG_GETMUTEX 11 /* sqlite3_mutex_methods* */
/* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */
#define SQLITE_CONFIG_LOOKASIDE 13 /* int int */
#define SQLITE_CONFIG_PCACHE 14 /* no-op */
#define SQLITE_CONFIG_GETPCACHE 15 /* no-op */
#define SQLITE_CONFIG_LOG 16 /* xFunc, void* */
#define SQLITE_CONFIG_URI 17 /* int */
#define SQLITE_CONFIG_PCACHE2 18 /* sqlite3_pcache_methods2* */
#define SQLITE_CONFIG_GETPCACHE2 19 /* sqlite3_pcache_methods2* */
#define SQLITE_CONFIG_SQLLOG 21 /* xSqllog, void* */
#define SQLITE_CONFIG_MMAP_SIZE 22 /* sqlite3_int64, sqlite3_int64 */
#define SQLITE_CONFIG_WIN32_HEAPSIZE 23 /* int nByte */
** CAPI3REF: Database Connection Configuration Options
** These constants are the available integer configuration options that
** can be passed as the second argument to the [sqlite3_db_config()] interface.
** New configuration options may be added in future releases of SQLite.
** Existing configuration options might be discontinued. Applications
** should check the return code from [sqlite3_db_config()] to make sure that
** the call worked. ^The [sqlite3_db_config()] interface will return a
** non-zero [error code] if a discontinued or unsupported configuration option
** is invoked.
** <dl>
** <dd> ^This option takes three additional arguments that determine the
** [lookaside memory allocator] configuration for the [database connection].
** ^The first argument (the third parameter to [sqlite3_db_config()] is a
** pointer to a memory buffer to use for lookaside memory.
** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
** may be NULL in which case SQLite will allocate the
** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
** size of each lookaside buffer slot. ^The third argument is the number of
** slots. The size of the buffer in the first argument must be greater than
** or equal to the product of the second and third arguments. The buffer
** must be aligned to an 8-byte boundary. ^If the second argument to
** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally
** rounded down to the next smaller multiple of 8. ^(The lookaside memory
** configuration for a database connection can only be changed when that
** connection is not currently using lookaside memory, or in other words
** when the "current value" returned by
** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
** Any attempt to change the lookaside memory configuration when lookaside
** memory is in use leaves the configuration unchanged and returns
** [SQLITE_BUSY].)^</dd>
** <dd> ^This option is used to enable or disable the enforcement of
** [foreign key constraints]. There should be two additional arguments.
** The first argument is an integer which is 0 to disable FK enforcement,
** positive to enable FK enforcement or negative to leave FK enforcement
** unchanged. The second parameter is a pointer to an integer into which
** is written 0 or 1 to indicate whether FK enforcement is off or on
** following this call. The second parameter may be a NULL pointer, in
** which case the FK enforcement setting is not reported back. </dd>
** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
** There should be two additional arguments.
** The first argument is an integer which is 0 to disable triggers,
** positive to enable triggers or negative to leave the setting unchanged.
** The second parameter is a pointer to an integer into which
** is written 0 or 1 to indicate whether triggers are disabled or enabled
** following this call. The second parameter may be a NULL pointer, in
** which case the trigger setting is not reported back. </dd>
** </dl>
#define SQLITE_DBCONFIG_LOOKASIDE 1001 /* void* int int */
#define SQLITE_DBCONFIG_ENABLE_FKEY 1002 /* int int* */
#define SQLITE_DBCONFIG_ENABLE_TRIGGER 1003 /* int int* */
** CAPI3REF: Enable Or Disable Extended Result Codes
** ^The sqlite3_extended_result_codes() routine enables or disables the
** [extended result codes] feature of SQLite. ^The extended result
** codes are disabled by default for historical compatibility.
SQLITE_API int sqlite3_extended_result_codes(sqlite3*, int onoff);
** CAPI3REF: Last Insert Rowid
** ^Each entry in most SQLite tables (except for [WITHOUT ROWID] tables)
** has a unique 64-bit signed
** integer key called the [ROWID | "rowid"]. ^The rowid is always available
** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
** names are not also used by explicitly declared columns. ^If
** the table has a column of type [INTEGER PRIMARY KEY] then that column
** is another alias for the rowid.
** ^The sqlite3_last_insert_rowid(D) interface returns the [rowid] of the
** most recent successful [INSERT] into a rowid table or [virtual table]
** on database connection D.
** ^Inserts into [WITHOUT ROWID] tables are not recorded.
** ^If no successful [INSERT]s into rowid tables
** have ever occurred on the database connection D,
** then sqlite3_last_insert_rowid(D) returns zero.
** ^(If an [INSERT] occurs within a trigger or within a [virtual table]
** method, then this routine will return the [rowid] of the inserted
** row as long as the trigger or virtual table method is running.
** But once the trigger or virtual table method ends, the value returned
** by this routine reverts to what it was before the trigger or virtual
** table method began.)^
** ^An [INSERT] that fails due to a constraint violation is not a
** successful [INSERT] and does not change the value returned by this
** and INSERT OR ABORT make no changes to the return value of this
** routine when their insertion fails. ^(When INSERT OR REPLACE
** encounters a constraint violation, it does not fail. The
** INSERT continues to completion after deleting rows that caused
** the constraint problem so INSERT OR REPLACE will always change
** the return value of this interface.)^
** ^For the purposes of this routine, an [INSERT] is considered to
** be successful even if it is subsequently rolled back.
** This function is accessible to SQL statements via the
** [last_insert_rowid() SQL function].
** If a separate thread performs a new [INSERT] on the same
** database connection while the [sqlite3_last_insert_rowid()]
** function is running and thus changes the last insert [rowid],
** then the value returned by [sqlite3_last_insert_rowid()] is
** unpredictable and might not equal either the old or the new
** last insert [rowid].
SQLITE_API sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);
** CAPI3REF: Count The Number Of Rows Modified
** ^This function returns the number of database rows that were changed
** or inserted or deleted by the most recently completed SQL statement
** on the [database connection] specified by the first parameter.
** ^(Only changes that are directly specified by the [INSERT], [UPDATE],
** or [DELETE] statement are counted. Auxiliary changes caused by
** triggers or [foreign key actions] are not counted.)^ Use the
** [sqlite3_total_changes()] function to find the total number of changes
** including changes caused by triggers and foreign key actions.
** ^Changes to a view that are simulated by an [INSTEAD OF trigger]
** are not counted. Only real table changes are counted.
** ^(A "row change" is a change to a single row of a single table
** caused by an INSERT, DELETE, or UPDATE statement. Rows that
** are changed as side effects of [REPLACE] constraint resolution,
** rollback, ABORT processing, [DROP TABLE], or by any other
** mechanisms do not count as direct row changes.)^
** A "trigger context" is a scope of execution that begins and
** ends with the script of a [CREATE TRIGGER | trigger].
** Most SQL statements are
** evaluated outside of any trigger. This is the "top level"
** trigger context. If a trigger fires from the top level, a
** new trigger context is entered for the duration of that one
** trigger. Subtriggers create subcontexts for their duration.
** ^Calling [sqlite3_exec()] or [sqlite3_step()] recursively does
** not create a new trigger context.
** ^This function returns the number of direct row changes in the
** most recent INSERT, UPDATE, or DELETE statement within the same
** trigger context.
** ^Thus, when called from the top level, this function returns the
** number of changes in the most recent INSERT, UPDATE, or DELETE
** that also occurred at the top level. ^(Within the body of a trigger,
** the sqlite3_changes() interface can be called to find the number of
** changes in the most recently completed INSERT, UPDATE, or DELETE
** statement within the body of the same trigger.
** However, the number returned does not include changes
** caused by subtriggers since those have their own context.)^
** See also the [sqlite3_total_changes()] interface, the
** [count_changes pragma], and the [changes() SQL function].
** If a separate thread makes changes on the same database connection
** while [sqlite3_changes()] is running then the value returned
** is unpredictable and not meaningful.
SQLITE_API int sqlite3_changes(sqlite3*);
** CAPI3REF: Total Number Of Rows Modified
** ^This function returns the number of row changes caused by [INSERT],
** [UPDATE] or [DELETE] statements since the [database connection] was opened.
** ^(The count returned by sqlite3_total_changes() includes all changes
** from all [CREATE TRIGGER | trigger] contexts and changes made by
** [foreign key actions]. However,
** the count does not include changes used to implement [REPLACE] constraints,
** do rollbacks or ABORT processing, or [DROP TABLE] processing. The
** count does not include rows of views that fire an [INSTEAD OF trigger],
** though if the INSTEAD OF trigger makes changes of its own, those changes
** are counted.)^
** ^The sqlite3_total_changes() function counts the changes as soon as
** the statement that makes them is completed (when the statement handle
** is passed to [sqlite3_reset()] or [sqlite3_finalize()]).
** See also the [sqlite3_changes()] interface, the
** [count_changes pragma], and the [total_changes() SQL function].
** If a separate thread makes changes on the same database connection
** while [sqlite3_total_changes()] is running then the value
** returned is unpredictable and not meaningful.
SQLITE_API int sqlite3_total_changes(sqlite3*);
** CAPI3REF: Interrupt A Long-Running Query
** ^This function causes any pending database operation to abort and
** return at its earliest opportunity. This routine is typically
** called in response to a user action such as pressing "Cancel"
** or Ctrl-C where the user wants a long query operation to halt
** immediately.
** ^It is safe to call this routine from a thread different from the
** thread that is currently running the database operation. But it
** is not safe to call this routine with a [database connection] that
** is closed or might close before sqlite3_interrupt() returns.
** ^If an SQL operation is very nearly finished at the time when
** sqlite3_interrupt() is called, then it might not have an opportunity
** to be interrupted and might continue to completion.
** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
** that is inside an explicit transaction, then the entire transaction
** will be rolled back automatically.
** ^The sqlite3_interrupt(D) call is in effect until all currently running
** SQL statements on [database connection] D complete. ^Any new SQL statements
** that are started after the sqlite3_interrupt() call and before the
** running statements reaches zero are interrupted as if they had been
** running prior to the sqlite3_interrupt() call. ^New SQL statements
** that are started after the running statement count reaches zero are
** not effected by the sqlite3_interrupt().
** ^A call to sqlite3_interrupt(D) that occurs when there are no running
** SQL statements is a no-op and has no effect on SQL statements
** that are started after the sqlite3_interrupt() call returns.
** If the database connection closes while [sqlite3_interrupt()]
** is running then bad things will likely happen.
SQLITE_API void sqlite3_interrupt(sqlite3*);
** CAPI3REF: Determine If An SQL Statement Is Complete
** These routines are useful during command-line input to determine if the
** currently entered text seems to form a complete SQL statement or
** if additional input is needed before sending the text into
** SQLite for parsing. ^These routines return 1 if the input string
** appears to be a complete SQL statement. ^A statement is judged to be
** complete if it ends with a semicolon token and is not a prefix of a
** well-formed CREATE TRIGGER statement. ^Semicolons that are embedded within
** string literals or quoted identifier names or comments are not
** independent tokens (they are part of the token in which they are
** embedded) and thus do not count as a statement terminator. ^Whitespace
** and comments that follow the final semicolon are ignored.
** ^These routines return 0 if the statement is incomplete. ^If a
** memory allocation fails, then SQLITE_NOMEM is returned.
** ^These routines do not parse the SQL statements thus
** will not detect syntactically incorrect SQL.
** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior
** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked
** automatically by sqlite3_complete16(). If that initialization fails,
** then the return value from sqlite3_complete16() will be non-zero
** regardless of whether or not the input SQL is complete.)^
** The input to [sqlite3_complete()] must be a zero-terminated
** UTF-8 string.
** The input to [sqlite3_complete16()] must be a zero-terminated
** UTF-16 string in native byte order.
SQLITE_API int sqlite3_complete(const char *sql);
SQLITE_API int sqlite3_complete16(const void *sql);
** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
** ^This routine sets a callback function that might be invoked whenever
** an attempt is made to open a database table that another thread
** or process has locked.
** ^If the busy callback is NULL, then [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED]
** is returned immediately upon encountering the lock. ^If the busy callback
** is not NULL, then the callback might be invoked with two arguments.
** ^The first argument to the busy handler is a copy of the void* pointer which
** is the third argument to sqlite3_busy_handler(). ^The second argument to
** the busy handler callback is the number of times that the busy handler has
** been invoked for this locking event. ^If the
** busy callback returns 0, then no additional attempts are made to
** access the database and [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED] is returned.
** ^If the callback returns non-zero, then another attempt
** is made to open the database for reading and the cycle repeats.
** The presence of a busy handler does not guarantee that it will be invoked
** when there is lock contention. ^If SQLite determines that invoking the busy
** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
** or [SQLITE_IOERR_BLOCKED] instead of invoking the busy handler.
** Consider a scenario where one process is holding a read lock that
** it is trying to promote to a reserved lock and
** a second process is holding a reserved lock that it is trying
** to promote to an exclusive lock. The first process cannot proceed
** because it is blocked by the second and the second process cannot
** proceed because it is blocked by the first. If both processes
** invoke the busy handlers, neither will make any progress. Therefore,
** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
** will induce the first process to release its read lock and allow
** the second process to proceed.
** ^The default busy callback is NULL.
** ^The [SQLITE_BUSY] error is converted to [SQLITE_IOERR_BLOCKED]
** when SQLite is in the middle of a large transaction where all the
** changes will not fit into the in-memory cache. SQLite will
** already hold a RESERVED lock on the database file, but it needs
** to promote this lock to EXCLUSIVE so that it can spill cache
** pages into the database file without harm to concurrent
** readers. ^If it is unable to promote the lock, then the in-memory
** cache will be left in an inconsistent state and so the error
** code is promoted from the relatively benign [SQLITE_BUSY] to
** the more severe [SQLITE_IOERR_BLOCKED]. ^This error code promotion
** forces an automatic rollback of the changes. See the
** <a href="/cvstrac/wiki?p=CorruptionFollowingBusyError">
** CorruptionFollowingBusyError</a> wiki page for a discussion of why
** this is important.
** ^(There can only be a single busy handler defined for each
** [database connection]. Setting a new busy handler clears any
** previously set handler.)^ ^Note that calling [sqlite3_busy_timeout()]
** will also set or clear the busy handler.
** The busy callback should not take any actions which modify the
** database connection that invoked the busy handler. Any such actions
** result in undefined behavior.
** A busy handler must not close the database connection
** or [prepared statement] that invoked the busy handler.
SQLITE_API int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);
** CAPI3REF: Set A Busy Timeout
** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
** for a specified amount of time when a table is locked. ^The handler
** will sleep multiple times until at least "ms" milliseconds of sleeping
** have accumulated. ^After at least "ms" milliseconds of sleeping,
** the handler returns 0 which causes [sqlite3_step()] to return
** ^Calling this routine with an argument less than or equal to zero
** turns off all busy handlers.
** ^(There can only be a single busy handler for a particular
** [database connection] any any given moment. If another busy handler
** was defined (using [sqlite3_busy_handler()]) prior to calling
** this routine, that other busy handler is cleared.)^
SQLITE_API int sqlite3_busy_timeout(sqlite3*, int ms);
** CAPI3REF: Convenience Routines For Running Queries
** This is a legacy interface that is preserved for backwards compatibility.
** Use of this interface is not recommended.
** Definition: A <b>result table</b> is memory data structure created by the
** [sqlite3_get_table()] interface. A result table records the
** complete query results from one or more queries.
** The table conceptually has a number of rows and columns. But
** these numbers are not part of the result table itself. These
** numbers are obtained separately. Let N be the number of rows
** and M be the number of columns.
** A result table is an array of pointers to zero-terminated UTF-8 strings.
** There are (N+1)*M elements in the array. The first M pointers point
** to zero-terminated strings that contain the names of the columns.
** The remaining entries all point to query results. NULL values result
** in NULL pointers. All other values are in their UTF-8 zero-terminated
** string representation as returned by [sqlite3_column_text()].
** A result table might consist of one or more memory allocations.
** It is not safe to pass a result table directly to [sqlite3_free()].
** A result table should be deallocated using [sqlite3_free_table()].
** ^(As an example of the result table format, suppose a query result
** is as follows:
** <blockquote><pre>
** Name | Age
** -----------------------
** Alice | 43
** Bob | 28
** Cindy | 21
** </pre></blockquote>
** There are two column (M==2) and three rows (N==3). Thus the
** result table has 8 entries. Suppose the result table is stored
** in an array names azResult. Then azResult holds this content:
** <blockquote><pre>
** azResult&#91;0] = "Name";
** azResult&#91;1] = "Age";
** azResult&#91;2] = "Alice";
** azResult&#91;3] = "43";
** azResult&#91;4] = "Bob";
** azResult&#91;5] = "28";
** azResult&#91;6] = "Cindy";
** azResult&#91;7] = "21";
** </pre></blockquote>)^
** ^The sqlite3_get_table() function evaluates one or more
** semicolon-separated SQL statements in the zero-terminated UTF-8
** string of its 2nd parameter and returns a result table to the
** pointer given in its 3rd parameter.
** After the application has finished with the result from sqlite3_get_table(),
** it must pass the result table pointer to sqlite3_free_table() in order to
** release the memory that was malloced. Because of the way the
** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
** function must not try to call [sqlite3_free()] directly. Only
** [sqlite3_free_table()] is able to release the memory properly and safely.
** The sqlite3_get_table() interface is implemented as a wrapper around
** [sqlite3_exec()]. The sqlite3_get_table() routine does not have access
** to any internal data structures of SQLite. It uses only the public
** interface defined here. As a consequence, errors that occur in the
** wrapper layer outside of the internal [sqlite3_exec()] call are not
** reflected in subsequent calls to [sqlite3_errcode()] or
** [sqlite3_errmsg()].
SQLITE_API int sqlite3_get_table(
sqlite3 *db, /* An open database */
const char *zSql, /* SQL to be evaluated */
char ***pazResult, /* Results of the query */
int *pnRow, /* Number of result rows written here */
int *pnColumn, /* Number of result columns written here */
char **pzErrmsg /* Error msg written here */
SQLITE_API void sqlite3_free_table(char **result);
** CAPI3REF: Formatted String Printing Functions
** These routines are work-alikes of the "printf()" family of functions
** from the standard C library.
** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
** results into memory obtained from [sqlite3_malloc()].
** The strings returned by these two routines should be
** released by [sqlite3_free()]. ^Both routines return a
** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
** memory to hold the resulting string.
** ^(The sqlite3_snprintf() routine is similar to "snprintf()" from
** the standard C library. The result is written into the
** buffer supplied as the second parameter whose size is given by
** the first parameter. Note that the order of the
** first two parameters is reversed from snprintf().)^ This is an
** historical accident that cannot be fixed without breaking
** backwards compatibility. ^(Note also that sqlite3_snprintf()
** returns a pointer to its buffer instead of the number of
** characters actually written into the buffer.)^ We admit that
** the number of characters written would be a more useful return
** value but we cannot change the implementation of sqlite3_snprintf()
** now without breaking compatibility.
** ^As long as the buffer size is greater than zero, sqlite3_snprintf()
** guarantees that the buffer is always zero-terminated. ^The first
** parameter "n" is the total size of the buffer, including space for
** the zero terminator. So the longest string that can be completely
** written will be n-1 characters.
** ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf().
** These routines all implement some additional formatting
** options that are useful for constructing SQL statements.
** All of the usual printf() formatting options apply. In addition, there
** is are "%q", "%Q", and "%z" options.
** ^(The %q option works like %s in that it substitutes a nul-terminated
** string from the argument list. But %q also doubles every '\'' character.
** %q is designed for use inside a string literal.)^ By doubling each '\''
** character it escapes that character and allows it to be inserted into
** the string.
** For example, assume the string variable zText contains text as follows:
** <blockquote><pre>
** char *zText = "It's a happy day!";
** </pre></blockquote>
** One can use this text in an SQL statement as follows:
** <blockquote><pre>
** char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);
** sqlite3_exec(db, zSQL, 0, 0, 0);
** sqlite3_free(zSQL);
** </pre></blockquote>
** Because the %q format string is used, the '\'' character in zText
** is escaped and the SQL generated is as follows:
** <blockquote><pre>
** INSERT INTO table1 VALUES('It''s a happy day!')
** </pre></blockquote>
** This is correct. Had we used %s instead of %q, the generated SQL
** would have looked like this:
** <blockquote><pre>
** INSERT INTO table1 VALUES('It's a happy day!');
** </pre></blockquote>
** This second example is an SQL syntax error. As a general rule you should
** always use %q instead of %s when inserting text into a string literal.
** ^(The %Q option works like %q except it also adds single quotes around
** the outside of the total string. Additionally, if the parameter in the
** argument list is a NULL pointer, %Q substitutes the text "NULL" (without
** single quotes).)^ So, for example, one could say:
** <blockquote><pre>
** char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);
** sqlite3_exec(db, zSQL, 0, 0, 0);
** sqlite3_free(zSQL);
** </pre></blockquote>
** The code above will render a correct SQL statement in the zSQL
** variable even if the zText variable is a NULL pointer.
** ^(The "%z" formatting option works like "%s" but with the
** addition that after the string has been read and copied into
** the result, [sqlite3_free()] is called on the input string.)^
SQLITE_API char *sqlite3_mprintf(const char*,...);
SQLITE_API char *sqlite3_vmprintf(const char*, va_list);
SQLITE_API char *sqlite3_snprintf(int,char*,const char*, ...);
SQLITE_API char *sqlite3_vsnprintf(int,char*,const char*, va_list);
** CAPI3REF: Memory Allocation Subsystem
** The SQLite core uses these three routines for all of its own
** internal memory allocation needs. "Core" in the previous sentence
** does not include operating-system specific VFS implementation. The
** Windows VFS uses native malloc() and free() for some operations.
** ^The sqlite3_malloc() routine returns a pointer to a block
** of memory at least N bytes in length, where N is the parameter.
** ^If sqlite3_malloc() is unable to obtain sufficient free
** memory, it returns a NULL pointer. ^If the parameter N to
** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
** a NULL pointer.
** ^Calling sqlite3_free() with a pointer previously returned
** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
** that it might be reused. ^The sqlite3_free() routine is
** a no-op if is called with a NULL pointer. Passing a NULL pointer
** to sqlite3_free() is harmless. After being freed, memory
** should neither be read nor written. Even reading previously freed
** memory might result in a segmentation fault or other severe error.
** Memory corruption, a segmentation fault, or other severe error
** might result if sqlite3_free() is called with a non-NULL pointer that
** was not obtained from sqlite3_malloc() or sqlite3_realloc().
** ^(The sqlite3_realloc() interface attempts to resize a
** prior memory allocation to be at least N bytes, where N is the
** second parameter. The memory allocation to be resized is the first
** parameter.)^ ^ If the first parameter to sqlite3_realloc()
** is a NULL pointer then its behavior is identical to calling
** sqlite3_malloc(N) where N is the second parameter to sqlite3_realloc().
** ^If the second parameter to sqlite3_realloc() is zero or
** negative then the behavior is exactly the same as calling
** sqlite3_free(P) where P is the first parameter to sqlite3_realloc().
** ^sqlite3_realloc() returns a pointer to a memory allocation
** of at least N bytes in size or NULL if sufficient memory is unavailable.
** ^If M is the size of the prior allocation, then min(N,M) bytes
** of the prior allocation are copied into the beginning of buffer returned
** by sqlite3_realloc() and the prior allocation is freed.
** ^If sqlite3_realloc() returns NULL, then the prior allocation
** is not freed.
** ^The memory returned by sqlite3_malloc() and sqlite3_realloc()
** is always aligned to at least an 8 byte boundary, or to a
** 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time
** option is used.
** In SQLite version 3.5.0 and 3.5.1, it was possible to define
** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
** implementation of these routines to be omitted. That capability
** is no longer provided. Only built-in memory allocators can be used.
** Prior to SQLite version 3.7.10, the Windows OS interface layer called
** the system malloc() and free() directly when converting
** filenames between the UTF-8 encoding used by SQLite
** and whatever filename encoding is used by the particular Windows
** installation. Memory allocation errors were detected, but
** they were reported back as [SQLITE_CANTOPEN] or
** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
** must be either NULL or else pointers obtained from a prior
** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
** not yet been released.
** The application must not read or write any part of
** a block of memory after it has been released using
** [sqlite3_free()] or [sqlite3_realloc()].
SQLITE_API void *sqlite3_malloc(int);
SQLITE_API void *sqlite3_realloc(void*, int);
SQLITE_API void sqlite3_free(void*);
** CAPI3REF: Memory Allocator Statistics
** SQLite provides these two interfaces for reporting on the status
** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
** routines, which form the built-in memory allocation subsystem.
** ^The [sqlite3_memory_used()] routine returns the number of bytes
** of memory currently outstanding (malloced but not freed).
** ^The [sqlite3_memory_highwater()] routine returns the maximum
** value of [sqlite3_memory_used()] since the high-water mark
** was last reset. ^The values returned by [sqlite3_memory_used()] and
** [sqlite3_memory_highwater()] include any overhead
** added by SQLite in its implementation of [sqlite3_malloc()],
** but not overhead added by the any underlying system library
** routines that [sqlite3_malloc()] may call.
** ^The memory high-water mark is reset to the current value of
** [sqlite3_memory_used()] if and only if the parameter to
** [sqlite3_memory_highwater()] is true. ^The value returned
** by [sqlite3_memory_highwater(1)] is the high-water mark
** prior to the reset.
SQLITE_API sqlite3_int64 sqlite3_memory_used(void);
SQLITE_API sqlite3_int64 sqlite3_memory_highwater(int resetFlag);
** CAPI3REF: Pseudo-Random Number Generator
** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
** select random [ROWID | ROWIDs] when inserting new records into a table that
** already uses the largest possible [ROWID]. The PRNG is also used for
** the build-in random() and randomblob() SQL functions. This interface allows
** applications to access the same PRNG for other purposes.
** ^A call to this routine stores N bytes of randomness into buffer P.
** ^The first time this routine is invoked (either internally or by
** the application) the PRNG is seeded using randomness obtained
** from the xRandomness method of the default [sqlite3_vfs] object.
** ^On all subsequent invocations, the pseudo-randomness is generated
** internally and without recourse to the [sqlite3_vfs] xRandomness
** method.
SQLITE_API void sqlite3_randomness(int N, void *P);
** CAPI3REF: Compile-Time Authorization Callbacks
** ^This routine registers an authorizer callback with a particular
** [database connection], supplied in the first argument.
** ^The authorizer callback is invoked as SQL statements are being compiled
** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()]. ^At various
** points during the compilation process, as logic is being created
** to perform various actions, the authorizer callback is invoked to
** see if those actions are allowed. ^The authorizer callback should
** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
** specific action but allow the SQL statement to continue to be
** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
** rejected with an error. ^If the authorizer callback returns
** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
** then the [sqlite3_prepare_v2()] or equivalent call that triggered
** the authorizer will fail with an error message.
** When the callback returns [SQLITE_OK], that means the operation
** requested is ok. ^When the callback returns [SQLITE_DENY], the
** [sqlite3_prepare_v2()] or equivalent call that triggered the
** authorizer will fail with an error message explaining that
** access is denied.
** ^The first parameter to the authorizer callback is a copy of the third
** parameter to the sqlite3_set_authorizer() interface. ^The second parameter
** to the callback is an integer [SQLITE_COPY | action code] that specifies
** the particular action to be authorized. ^The third through sixth parameters
** to the callback are zero-terminated strings that contain additional
** details about the action to be authorized.
** ^If the action code is [SQLITE_READ]
** and the callback returns [SQLITE_IGNORE] then the
** [prepared statement] statement is constructed to substitute
** a NULL value in place of the table column that would have
** been read if [SQLITE_OK] had been returned. The [SQLITE_IGNORE]
** return can be used to deny an untrusted user access to individual
** columns of a table.
** ^If the action code is [SQLITE_DELETE] and the callback returns
** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the
** [truncate optimization] is disabled and all rows are deleted individually.
** An authorizer is used when [sqlite3_prepare | preparing]
** SQL statements from an untrusted source, to ensure that the SQL statements
** do not try to access data they are not allowed to see, or that they do not
** try to execute malicious statements that damage the database. For
** example, an application may allow a user to enter arbitrary
** SQL queries for evaluation by a database. But the application does
** not want the user to be able to make arbitrary changes to the
** database. An authorizer could then be put in place while the
** user-entered SQL is being [sqlite3_prepare | prepared] that
** disallows everything except [SELECT] statements.
** Applications that need to process SQL from untrusted sources
** might also consider lowering resource limits using [sqlite3_limit()]
** and limiting database size using the [max_page_count] [PRAGMA]
** in addition to using an authorizer.
** ^(Only a single authorizer can be in place on a database connection
** at a time. Each call to sqlite3_set_authorizer overrides the
** previous call.)^ ^Disable the authorizer by installing a NULL callback.
** The authorizer is disabled by default.
** The authorizer callback must not do anything that will modify
** the database connection that invoked the authorizer callback.
** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
** database connections for the meaning of "modify" in this paragraph.
** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the
** statement might be re-prepared during [sqlite3_step()] due to a
** schema change. Hence, the application should ensure that the
** correct authorizer callback remains in place during the [sqlite3_step()].
** ^Note that the authorizer callback is invoked only during
** [sqlite3_prepare()] or its variants. Authorization is not
** performed during statement evaluation in [sqlite3_step()], unless
** as stated in the previous paragraph, sqlite3_step() invokes
** sqlite3_prepare_v2() to reprepare a statement after a schema change.
SQLITE_API int sqlite3_set_authorizer(
int (*xAuth)(void*,int,const char*,const char*,const char*,const char*),
void *pUserData
** CAPI3REF: Authorizer Return Codes
** The [sqlite3_set_authorizer | authorizer callback function] must
** return either [SQLITE_OK] or one of these two constants in order
** to signal SQLite whether or not the action is permitted. See the
** [sqlite3_set_authorizer | authorizer documentation] for additional
** information.
** Note that SQLITE_IGNORE is also used as a [SQLITE_ROLLBACK | return code]
** from the [sqlite3_vtab_on_conflict()] interface.
#define SQLITE_DENY 1 /* Abort the SQL statement with an error */
#define SQLITE_IGNORE 2 /* Don't allow access, but don't generate an error */
** CAPI3REF: Authorizer Action Codes
** The [sqlite3_set_authorizer()] interface registers a callback function
** that is invoked to authorize certain SQL statement actions. The
** second parameter to the callback is an integer code that specifies
** what action is being authorized. These are the integer action codes that
** the authorizer callback may be passed.
** These action code values signify what kind of operation is to be
** authorized. The 3rd and 4th parameters to the authorization
** callback function will be parameters or NULL depending on which of these
** codes is used as the second parameter. ^(The 5th parameter to the
** authorizer callback is the name of the database ("main", "temp",
** etc.) if applicable.)^ ^The 6th parameter to the authorizer callback
** is the name of the inner-most trigger or view that is responsible for
** the access attempt or NULL if this access attempt is directly from
** top-level SQL code.
/******************************************* 3rd ************ 4th ***********/
#define SQLITE_CREATE_INDEX 1 /* Index Name Table Name */
#define SQLITE_CREATE_TABLE 2 /* Table Name NULL */
#define SQLITE_CREATE_TEMP_INDEX 3 /* Index Name Table Name */
#define SQLITE_CREATE_TEMP_TABLE 4 /* Table Name NULL */
#define SQLITE_CREATE_TEMP_TRIGGER 5 /* Trigger Name Table Name */
#define SQLITE_CREATE_TEMP_VIEW 6 /* View Name NULL */
#define SQLITE_CREATE_TRIGGER 7 /* Trigger Name Table Name */
#define SQLITE_CREATE_VIEW 8 /* View Name NULL */
#define SQLITE_DELETE 9 /* Table Name NULL */
#define SQLITE_DROP_INDEX 10 /* Index Name Table Name */
#define SQLITE_DROP_TABLE 11 /* Table Name NULL */
#define SQLITE_DROP_TEMP_INDEX 12 /* Index Name Table Name */
#define SQLITE_DROP_TEMP_TABLE 13 /* Table Name NULL */
#define SQLITE_DROP_TEMP_TRIGGER 14 /* Trigger Name Table Name */
#define SQLITE_DROP_TEMP_VIEW 15 /* View Name NULL */
#define SQLITE_DROP_TRIGGER 16 /* Trigger Name Table Name */
#define SQLITE_DROP_VIEW 17 /* View Name NULL */
#define SQLITE_INSERT 18 /* Table Name NULL */
#define SQLITE_PRAGMA 19 /* Pragma Name 1st arg or NULL */
#define SQLITE_READ 20 /* Table Name Column Name */
#define SQLITE_SELECT 21 /* NULL NULL */
#define SQLITE_TRANSACTION 22 /* Operation NULL */
#define SQLITE_UPDATE 23 /* Table Name Column Name */
#define SQLITE_ATTACH 24 /* Filename NULL */
#define SQLITE_DETACH 25 /* Database Name NULL */
#define SQLITE_ALTER_TABLE 26 /* Database Name Table Name */
#define SQLITE_REINDEX 27 /* Index Name NULL */
#define SQLITE_ANALYZE 28 /* Table Name NULL */
#define SQLITE_CREATE_VTABLE 29 /* Table Name Module Name */
#define SQLITE_DROP_VTABLE 30 /* Table Name Module Name */
#define SQLITE_FUNCTION 31 /* NULL Function Name */
#define SQLITE_SAVEPOINT 32 /* Operation Savepoint Name */
#define SQLITE_COPY 0 /* No longer used */
** CAPI3REF: Tracing And Profiling Functions
** These routines register callback functions that can be used for
** tracing and profiling the execution of SQL statements.
** ^The callback function registered by sqlite3_trace() is invoked at
** various times when an SQL statement is being run by [sqlite3_step()].
** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
** SQL statement text as the statement first begins executing.
** ^(Additional sqlite3_trace() callbacks might occur
** as each triggered subprogram is entered. The callbacks for triggers
** contain a UTF-8 SQL comment that identifies the trigger.)^
** The [SQLITE_TRACE_SIZE_LIMIT] compile-time option can be used to limit
** the length of [bound parameter] expansion in the output of sqlite3_trace().
** ^The callback function registered by sqlite3_profile() is invoked
** as each SQL statement finishes. ^The profile callback contains
** the original statement text and an estimate of wall-clock time
** of how long that statement took to run. ^The profile callback
** time is in units of nanoseconds, however the current implementation
** is only capable of millisecond resolution so the six least significant
** digits in the time are meaningless. Future versions of SQLite
** might provide greater resolution on the profiler callback. The
** sqlite3_profile() function is considered experimental and is
** subject to change in future versions of SQLite.
SQLITE_API void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*);
SQLITE_API SQLITE_EXPERIMENTAL void *sqlite3_profile(sqlite3*,
void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
** CAPI3REF: Query Progress Callbacks
** ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback
** function X to be invoked periodically during long running calls to
** [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for
** database connection D. An example use for this
** interface is to keep a GUI updated during a large query.
** ^The parameter P is passed through as the only parameter to the
** callback function X. ^The parameter N is the approximate number of
** [virtual machine instructions] that are evaluated between successive
** invocations of the callback X. ^If N is less than one then the progress
** handler is disabled.
** ^Only a single progress handler may be defined at one time per
** [database connection]; setting a new progress handler cancels the
** old one. ^Setting parameter X to NULL disables the progress handler.
** ^The progress handler is also disabled by setting N to a value less
** than 1.
** ^If the progress callback returns non-zero, the operation is
** interrupted. This feature can be used to implement a
** "Cancel" button on a GUI progress dialog box.
** The progress handler callback must not do anything that will modify
** the database connection that invoked the progress handler.
** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
** database connections for the meaning of "modify" in this paragraph.
SQLITE_API void sqlite3_progress_handler(sqlite3*, int, int(*)(void*), void*);
** CAPI3REF: Opening A New Database Connection
** ^These routines open an SQLite database file as specified by the
** filename argument. ^The filename argument is interpreted as UTF-8 for
** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
** order for sqlite3_open16(). ^(A [database connection] handle is usually
** returned in *ppDb, even if an error occurs. The only exception is that
** if SQLite is unable to allocate memory to hold the [sqlite3] object,
** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
** object.)^ ^(If the database is opened (and/or created) successfully, then
** [SQLITE_OK] is returned. Otherwise an [error code] is returned.)^ ^The
** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
** an English language description of the error following a failure of any
** of the sqlite3_open() routines.
** ^The default encoding for the database will be UTF-8 if
** sqlite3_open() or sqlite3_open_v2() is called and
** UTF-16 in the native byte order if sqlite3_open16() is used.
** Whether or not an error occurs when it is opened, resources
** associated with the [database connection] handle should be released by
** passing it to [sqlite3_close()] when it is no longer required.
** The sqlite3_open_v2() interface works like sqlite3_open()
** except that it accepts two additional parameters for additional control
** over the new database connection. ^(The flags parameter to
** sqlite3_open_v2() can take one of
** the following three values, optionally combined with the
** <dl>
** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
** <dd>The database is opened in read-only mode. If the database does not
** already exist, an error is returned.</dd>)^
** <dd>The database is opened for reading and writing if possible, or reading
** only if the file is write protected by the operating system. In either
** case the database must already exist, otherwise an error is returned.</dd>)^
** <dd>The database is opened for reading and writing, and is created if
** it does not already exist. This is the behavior that is always used for
** sqlite3_open() and sqlite3_open16().</dd>)^
** </dl>
** If the 3rd parameter to sqlite3_open_v2() is not one of the
** combinations shown above optionally combined with other
** then the behavior is undefined.
** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
** opens in the multi-thread [threading mode] as long as the single-thread
** mode has not been set at compile-time or start-time. ^If the
** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
** in the serialized [threading mode] unless single-thread was
** previously selected at compile-time or start-time.
** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be
** eligible to use [shared cache mode], regardless of whether or not shared
** cache is enabled using [sqlite3_enable_shared_cache()]. ^The
** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not
** participate in [shared cache mode] even if it is enabled.
** ^The fourth parameter to sqlite3_open_v2() is the name of the
** [sqlite3_vfs] object that defines the operating system interface that
** the new database connection should use. ^If the fourth parameter is
** a NULL pointer then the default [sqlite3_vfs] object is used.
** ^If the filename is ":memory:", then a private, temporary in-memory database
** is created for the connection. ^This in-memory database will vanish when
** the database connection is closed. Future versions of SQLite might
** make use of additional special filenames that begin with the ":" character.
** It is recommended that when a database filename actually does begin with
** a ":" character you should prefix the filename with a pathname such as
** "./" to avoid ambiguity.
** ^If the filename is an empty string, then a private, temporary
** on-disk database will be created. ^This private database will be
** automatically deleted as soon as the database connection is closed.
** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
** ^If [URI filename] interpretation is enabled, and the filename argument
** begins with "file:", then the filename is interpreted as a URI. ^URI
** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
** set in the fourth argument to sqlite3_open_v2(), or if it has
** been enabled globally using the [SQLITE_CONFIG_URI] option with the
** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
** As of SQLite version 3.7.7, URI filename interpretation is turned off
** by default, but future releases of SQLite might enable URI filename
** interpretation by default. See "[URI filenames]" for additional
** information.
** URI filenames are parsed according to RFC 3986. ^If the URI contains an
** authority, then it must be either an empty string or the string
** "localhost". ^If the authority is not an empty string or "localhost", an
** error is returned to the caller. ^The fragment component of a URI, if
** present, is ignored.
** ^SQLite uses the path component of the URI as the name of the disk file
** which contains the database. ^If the path begins with a '/' character,
** then it is interpreted as an absolute path. ^If the path does not begin
** with a '/' (meaning that the authority section is omitted from the URI)
** then the path is interpreted as a relative path.
** ^On windows, the first component of an absolute path
** is a drive specification (e.g. "C:").
** [[core URI query parameters]]
** The query component of a URI may contain parameters that are interpreted
** either by SQLite itself, or by a [VFS | custom VFS implementation].
** SQLite interprets the following three query parameters:
** <ul>
** <li> <b>vfs</b>: ^The "vfs" parameter may be used to specify the name of
** a VFS object that provides the operating system interface that should
** be used to access the database file on disk. ^If this option is set to
** an empty string the default VFS object is used. ^Specifying an unknown
** VFS is an error. ^If sqlite3_open_v2() is used and the vfs option is
** present, then the VFS specified by the option takes precedence over
** the value passed as the fourth parameter to sqlite3_open_v2().
** <li> <b>mode</b>: ^(The mode parameter may be set to either "ro", "rw",
** "rwc", or "memory". Attempting to set it to any other value is
** an error)^.
** ^If "ro" is specified, then the database is opened for read-only
** access, just as if the [SQLITE_OPEN_READONLY] flag had been set in the
** third argument to sqlite3_open_v2(). ^If the mode option is set to
** "rw", then the database is opened for read-write (but not create)
** access, as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had
** been set. ^Value "rwc" is equivalent to setting both
** set to "memory" then a pure [in-memory database] that never reads
** or writes from disk is used. ^It is an error to specify a value for
** the mode parameter that is less restrictive than that specified by
** the flags passed in the third parameter to sqlite3_open_v2().
** <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or
** "private". ^Setting it to "shared" is equivalent to setting the
** SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to
** sqlite3_open_v2(). ^Setting the cache parameter to "private" is
** equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit.
** ^If sqlite3_open_v2() is used and the "cache" parameter is present in
** a URI filename, its value overrides any behavior requested by setting
** </ul>
** ^Specifying an unknown parameter in the query component of a URI is not an
** error. Future versions of SQLite might understand additional query
** parameters. See "[query parameters with special meaning to SQLite]" for
** additional information.
** [[URI filename examples]] <h3>URI filename examples</h3>
** <table border="1" align=center cellpadding=5>
** <tr><th> URI filenames <th> Results
** <tr><td> file:data.db <td>
** Open the file "data.db" in the current directory.
** <tr><td> file:/home/fred/data.db<br>
** file:///home/fred/data.db <br>
** file://localhost/home/fred/data.db <br> <td>
** Open the database file "/home/fred/data.db".
** <tr><td> file://darkstar/home/fred/data.db <td>
** An error. "darkstar" is not a recognized authority.
** <tr><td style="white-space:nowrap">
** file:///C:/Documents%20and%20Settings/fred/Desktop/data.db
** <td> Windows only: Open the file "data.db" on fred's desktop on drive
** C:. Note that the %20 escaping in this example is not strictly
** necessary - space characters can be used literally
** in URI filenames.
** <tr><td> file:data.db?mode=ro&cache=private <td>
** Open file "data.db" in the current directory for read-only access.
** Regardless of whether or not shared-cache mode is enabled by
** default, use a private cache.
** <tr><td> file:/home/fred/data.db?vfs=unix-nolock <td>
** Open file "/home/fred/data.db". Use the special VFS "unix-nolock".
** <tr><td> file:data.db?mode=readonly <td>
** An error. "readonly" is not a valid option for the "mode" parameter.
** </table>
** ^URI hexadecimal escape sequences (%HH) are supported within the path and
** query components of a URI. A hexadecimal escape sequence consists of a
** percent sign - "%" - followed by exactly two hexadecimal digits
** specifying an octet value. ^Before the path or query components of a
** URI filename are interpreted, they are encoded using UTF-8 and all
** hexadecimal escape sequences replaced by a single byte containing the
** corresponding octet. If this process generates an invalid UTF-8 encoding,
** the results are undefined.
** <b>Note to Windows users:</b> The encoding used for the filename argument
** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
** codepage is currently defined. Filenames containing international
** characters must be converted to UTF-8 prior to passing them into
** sqlite3_open() or sqlite3_open_v2().
** <b>Note to Windows Runtime users:</b> The temporary directory must be set
** prior to calling sqlite3_open() or sqlite3_open_v2(). Otherwise, various
** features that require the use of temporary files may fail.
** See also: [sqlite3_temp_directory]
SQLITE_API int sqlite3_open(
const char *filename, /* Database filename (UTF-8) */
sqlite3 **ppDb /* OUT: SQLite db handle */
SQLITE_API int sqlite3_open16(
const void *filename, /* Database filename (UTF-16) */
sqlite3 **ppDb /* OUT: SQLite db handle */
SQLITE_API int sqlite3_open_v2(
const char *filename, /* Database filename (UTF-8) */
sqlite3 **ppDb, /* OUT: SQLite db handle */
int flags, /* Flags */
const char *zVfs /* Name of VFS module to use */
** CAPI3REF: Obtain Values For URI Parameters
** These are utility routines, useful to VFS implementations, that check
** to see if a database file was a URI that contained a specific query
** parameter, and if so obtains the value of that query parameter.
** If F is the database filename pointer passed into the xOpen() method of
** a VFS implementation when the flags parameter to xOpen() has one or
** more of the [SQLITE_OPEN_URI] or [SQLITE_OPEN_MAIN_DB] bits set and
** P is the name of the query parameter, then
** sqlite3_uri_parameter(F,P) returns the value of the P
** parameter if it exists or a NULL pointer if P does not appear as a
** query parameter on F. If P is a query parameter of F
** has no explicit value, then sqlite3_uri_parameter(F,P) returns
** a pointer to an empty string.
** The sqlite3_uri_boolean(F,P,B) routine assumes that P is a boolean
** parameter and returns true (1) or false (0) according to the value
** of P. The sqlite3_uri_boolean(F,P,B) routine returns true (1) if the
** value of query parameter P is one of "yes", "true", or "on" in any
** case or if the value begins with a non-zero number. The
** sqlite3_uri_boolean(F,P,B) routines returns false (0) if the value of
** query parameter P is one of "no", "false", or "off" in any case or
** if the value begins with a numeric zero. If P is not a query
** parameter on F or if the value of P is does not match any of the
** above, then sqlite3_uri_boolean(F,P,B) returns (B!=0).
** The sqlite3_uri_int64(F,P,D) routine converts the value of P into a
** 64-bit signed integer and returns that integer, or D if P does not
** exist. If the value of P is something other than an integer, then
** zero is returned.
** If F is a NULL pointer, then sqlite3_uri_parameter(F,P) returns NULL and
** sqlite3_uri_boolean(F,P,B) returns B. If F is not a NULL pointer and
** is not a database file pathname pointer that SQLite passed into the xOpen
** VFS method, then the behavior of this routine is undefined and probably
** undesirable.
SQLITE_API const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam);
SQLITE_API int sqlite3_uri_boolean(const char *zFile, const char *zParam, int bDefault);
SQLITE_API sqlite3_int64 sqlite3_uri_int64(const char*, const char*, sqlite3_int64);
** CAPI3REF: Error Codes And Messages
** ^The sqlite3_errcode() interface returns the numeric [result code] or
** [extended result code] for the most recent failed sqlite3_* API call
** associated with a [database connection]. If a prior API call failed
** but the most recent API call succeeded, the return value from
** sqlite3_errcode() is undefined. ^The sqlite3_extended_errcode()
** interface is the same except that it always returns the
** [extended result code] even when extended result codes are
** disabled.
** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
** text that describes the error, as either UTF-8 or UTF-16 respectively.
** ^(Memory to hold the error message string is managed internally.
** The application does not need to worry about freeing the result.
** However, the error string might be overwritten or deallocated by
** subsequent calls to other SQLite interface functions.)^
** ^The sqlite3_errstr() interface returns the English-language text
** that describes the [result code], as UTF-8.
** ^(Memory to hold the error message string is managed internally
** and must not be freed by the application)^.
** When the serialized [threading mode] is in use, it might be the
** case that a second error occurs on a separate thread in between
** the time of the first error and the call to these interfaces.
** When that happens, the second error will be reported since these
** interfaces always report the most recent result. To avoid
** this, each thread can obtain exclusive use of the [database connection] D
** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
** all calls to the interfaces listed here are completed.
** If an interface fails with SQLITE_MISUSE, that means the interface
** was invoked incorrectly by the application. In that case, the
** error code and message may or may not be set.
SQLITE_API int sqlite3_errcode(sqlite3 *db);
SQLITE_API int sqlite3_extended_errcode(sqlite3 *db);
SQLITE_API const char *sqlite3_errmsg(sqlite3*);
SQLITE_API const void *sqlite3_errmsg16(sqlite3*);
SQLITE_API const char *sqlite3_errstr(int);
** CAPI3REF: SQL Statement Object
** KEYWORDS: {prepared statement} {prepared statements}
** An instance of this object represents a single SQL statement.
** This object is variously known as a "prepared statement" or a
** "compiled SQL statement" or simply as a "statement".
** The life of a statement object goes something like this:
** <ol>
** <li> Create the object using [sqlite3_prepare_v2()] or a related
** function.
** <li> Bind values to [host parameters] using the sqlite3_bind_*()
** interfaces.
** <li> Run the SQL by calling [sqlite3_step()] one or more times.
** <li> Reset the statement using [sqlite3_reset()] then go back
** to step 2. Do this zero or more times.
** <li> Destroy the object using [sqlite3_finalize()].
** </ol>
** Refer to documentation on individual methods above for additional
** information.
typedef struct sqlite3_stmt sqlite3_stmt;
** CAPI3REF: Run-time Limits
** ^(This interface allows the size of various constructs to be limited
** on a connection by connection basis. The first parameter is the
** [database connection] whose limit is to be set or queried. The
** second parameter is one of the [limit categories] that define a
** class of constructs to be size limited. The third parameter is the
** new limit for that construct.)^
** ^If the new limit is a negative number, the limit is unchanged.
** ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a
** [limits | hard upper bound]
** set at compile-time by a C preprocessor macro called
** [limits | SQLITE_MAX_<i>NAME</i>].
** (The "_LIMIT_" in the name is changed to "_MAX_".))^
** ^Attempts to increase a limit above its hard upper bound are
** silently truncated to the hard upper bound.
** ^Regardless of whether or not the limit was changed, the
** [sqlite3_limit()] interface returns the prior value of the limit.
** ^Hence, to find the current value of a limit without changing it,
** simply invoke this interface with the third parameter set to -1.
** Run-time limits are intended for use in applications that manage
** both their own internal database and also databases that are controlled
** by untrusted external sources. An example application might be a
** web browser that has its own databases for storing history and
** separate databases controlled by JavaScript applications downloaded
** off the Internet. The internal databases can be given the
** large, default limits. Databases managed by external sources can
** be given much smaller limits designed to prevent a denial of service
** attack. Developers might also want to use the [sqlite3_set_authorizer()]
** interface to further control untrusted SQL. The size of the database
** created by an untrusted script can be contained using the
** [max_page_count] [PRAGMA].
** New run-time limit categories may be added in future releases.
SQLITE_API int sqlite3_limit(sqlite3*, int id, int newVal);
** CAPI3REF: Run-Time Limit Categories
** KEYWORDS: {limit category} {*limit categories}
** These constants define various performance limits
** that can be lowered at run-time using [sqlite3_limit()].
** The synopsis of the meanings of the various limits is shown below.
** Additional information is available at [limits | Limits in SQLite].
** <dl>
** <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^
** <dd>The maximum length of an SQL statement, in bytes.</dd>)^
** <dd>The maximum number of columns in a table definition or in the
** result set of a [SELECT] or the maximum number of columns in an index
** or in an ORDER BY or GROUP BY clause.</dd>)^
** <dd>The maximum depth of the parse tree on any expression.</dd>)^
** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^
** <dd>The maximum number of instructions in a virtual machine program
** used to implement an SQL statement. This limit is not currently
** enforced, though that might be added in some future release of
** SQLite.</dd>)^
** <dd>The maximum number of arguments on a function.</dd>)^
** <dd>The maximum number of [ATTACH | attached databases].)^</dd>
** <dd>The maximum length of the pattern argument to the [LIKE] or
** [GLOB] operators.</dd>)^
** <dd>The maximum index number of any [parameter] in an SQL statement.)^
** <dd>The maximum depth of recursion for triggers.</dd>)^
** </dl>