DBD-SQLeet
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** 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 ensure 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: {result code definitions}
**
** 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: [extended result code definitions]
*/
#define SQLITE_OK 0 /* Successful result */
/* beginning-of-error-codes */
#define SQLITE_ERROR 1 /* Generic error */
#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 /* Internal use only */
#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 /* Not used */
#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 result code definitions}
**
** In its default configuration, SQLite API routines return one of 30 integer
** [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 [dateof:3.3.8]
** and later) include
** support for additional result codes that provide more detailed information
** about errors. These [extended result codes] are enabled or disabled
** on a per database connection basis using the
** [sqlite3_extended_result_codes()] API. Or, the extended code for
** the most recent error can be obtained using
** [sqlite3_extended_errcode()].
*/
#define SQLITE_ERROR_MISSING_COLLSEQ (SQLITE_ERROR | (1<<8))
#define SQLITE_ERROR_RETRY (SQLITE_ERROR | (2<<8))
#define SQLITE_ERROR_SNAPSHOT (SQLITE_ERROR | (3<<8))
#define SQLITE_IOERR_READ (SQLITE_IOERR | (1<<8))
#define SQLITE_IOERR_SHORT_READ (SQLITE_IOERR | (2<<8))
#define SQLITE_IOERR_WRITE (SQLITE_IOERR | (3<<8))
#define SQLITE_IOERR_FSYNC (SQLITE_IOERR | (4<<8))
#define SQLITE_IOERR_DIR_FSYNC (SQLITE_IOERR | (5<<8))
#define SQLITE_IOERR_TRUNCATE (SQLITE_IOERR | (6<<8))
#define SQLITE_IOERR_FSTAT (SQLITE_IOERR | (7<<8))
#define SQLITE_IOERR_UNLOCK (SQLITE_IOERR | (8<<8))
#define SQLITE_IOERR_RDLOCK (SQLITE_IOERR | (9<<8))
#define SQLITE_IOERR_DELETE (SQLITE_IOERR | (10<<8))
#define SQLITE_IOERR_BLOCKED (SQLITE_IOERR | (11<<8))
#define SQLITE_IOERR_NOMEM (SQLITE_IOERR | (12<<8))
#define SQLITE_IOERR_ACCESS (SQLITE_IOERR | (13<<8))
#define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
** interface.
**
** <ul>
** <li>[[SQLITE_FCNTL_LOCKSTATE]]
** 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],
** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
** into an integer that the pArg argument points to. This capability
** is used during testing and is only available when the SQLITE_TEST
** compile-time option is used.
**
** <li>[[SQLITE_FCNTL_SIZE_HINT]]
** 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.
**
** <li>[[SQLITE_FCNTL_CHUNK_SIZE]]
** 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.
**
** <li>[[SQLITE_FCNTL_FILE_POINTER]]
** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
** to the [sqlite3_file] object associated with a particular database
** connection. See also [SQLITE_FCNTL_JOURNAL_POINTER].
**
** <li>[[SQLITE_FCNTL_JOURNAL_POINTER]]
** The [SQLITE_FCNTL_JOURNAL_POINTER] opcode is used to obtain a pointer
** to the [sqlite3_file] object associated with the journal file (either
** the [rollback journal] or the [write-ahead log]) for a particular database
** connection. See also [SQLITE_FCNTL_FILE_POINTER].
**
** <li>[[SQLITE_FCNTL_SYNC_OMITTED]]
** No longer in use.
**
** <li>[[SQLITE_FCNTL_SYNC]]
** The [SQLITE_FCNTL_SYNC] opcode is generated internally by SQLite and
** sent to the VFS immediately before the xSync method is invoked on a
** database file descriptor. Or, if the xSync method is not invoked
** because the user has configured SQLite with
** [PRAGMA synchronous | PRAGMA synchronous=OFF] it is invoked in place
** of the xSync method. In most cases, the pointer argument passed with
** this file-control is NULL. However, if the database file is being synced
** as part of a multi-database commit, the argument points to a nul-terminated
** string containing the transactions master-journal file name. VFSes that
** do not need this signal 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.
**
** <li>[[SQLITE_FCNTL_COMMIT_PHASETWO]]
** The [SQLITE_FCNTL_COMMIT_PHASETWO] opcode is generated internally by SQLite
** and sent to the VFS after a transaction has been committed immediately
** but before the database is unlocked. VFSes that do not need this signal
** 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.
**
** <li>[[SQLITE_FCNTL_WIN32_AV_RETRY]]
** ^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 is 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.
**
** <li>[[SQLITE_FCNTL_PERSIST_WAL]]
** ^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 ([WAL file]) 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.
**
** <li>[[SQLITE_FCNTL_POWERSAFE_OVERWRITE]]
** ^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.
**
** <li>[[SQLITE_FCNTL_OVERWRITE]]
** ^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.
**
** <li>[[SQLITE_FCNTL_VFSNAME]]
** ^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
** 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 future 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_EXISTS 0
#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>
** <li> SQLITE_SHM_LOCK | SQLITE_SHM_SHARED
** <li> SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE
** <li> SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED
** <li> SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE
** </ul>
**
** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
** was given on the corresponding lock.
**
** The xShmLock method can transition between unlocked and SHARED or
** between unlocked and EXCLUSIVE. It cannot transition between SHARED
** and EXCLUSIVE.
*/
#define SQLITE_SHM_UNLOCK 1
#define SQLITE_SHM_LOCK 2
#define SQLITE_SHM_SHARED 4
#define SQLITE_SHM_EXCLUSIVE 8
/*
** 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
*/
#define SQLITE_SHM_NLOCK 8
/*
** 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
** 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.
*/
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
** KEYWORDS: {busy-handler callback} {busy handler}
** METHOD: sqlite3
**
** ^The sqlite3_busy_handler(D,X,P) routine sets a callback function X
** that might be invoked with argument P whenever
** an attempt is made to access a database table associated with
** [database connection] D when another thread
** or process has the table locked.
** The sqlite3_busy_handler() interface is used to implement
** [sqlite3_busy_timeout()] and [PRAGMA busy_timeout].
**
** ^If the busy callback is NULL, then [SQLITE_BUSY]
** 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 previously for the same locking event. ^If the
** busy callback returns 0, then no additional attempts are made to
** access the database and [SQLITE_BUSY] is returned
** to the application.
** ^If the callback returns non-zero, then another attempt
** is made to access the database 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]
** to the application 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.
**
** ^(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()]
** or evaluating [PRAGMA busy_timeout=N] will change the
** busy handler and thus clear any previously set busy handler.
**
** The busy callback should not take any actions which modify the
** database connection that invoked the busy handler. In other words,
** the busy handler is not reentrant. 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
** METHOD: sqlite3
**
** ^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
** [SQLITE_BUSY].
**
** ^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] at any given moment. If another busy handler
** was defined (using [sqlite3_busy_handler()]) prior to calling
** this routine, that other busy handler is cleared.)^
**
** See also: [PRAGMA busy_timeout]
*/
SQLITE_API int sqlite3_busy_timeout(sqlite3*, int ms);
/*
** CAPI3REF: Convenience Routines For Running Queries
** METHOD: sqlite3
**
** 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>
int iVersion;
void *pArg;
int (*xInit)(void*);
void (*xShutdown)(void*);
sqlite3_pcache *(*xCreate)(int szPage, int szExtra, int bPurgeable);
void (*xCachesize)(sqlite3_pcache*, int nCachesize);
int (*xPagecount)(sqlite3_pcache*);
sqlite3_pcache_page *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
void (*xUnpin)(sqlite3_pcache*, sqlite3_pcache_page*, int discard);
void (*xRekey)(sqlite3_pcache*, sqlite3_pcache_page*,
unsigned oldKey, unsigned newKey);
void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
void (*xDestroy)(sqlite3_pcache*);
void (*xShrink)(sqlite3_pcache*);
};
/*
** This is the obsolete pcache_methods object that has now been replaced
** by sqlite3_pcache_methods2. This object is not used by SQLite. It is
** retained in the header file for backwards compatibility only.
*/
typedef struct sqlite3_pcache_methods sqlite3_pcache_methods;
struct sqlite3_pcache_methods {
void *pArg;
int (*xInit)(void*);
void (*xShutdown)(void*);
sqlite3_pcache *(*xCreate)(int szPage, int bPurgeable);
void (*xCachesize)(sqlite3_pcache*, int nCachesize);
int (*xPagecount)(sqlite3_pcache*);
void *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag);
void (*xUnpin)(sqlite3_pcache*, void*, int discard);
void (*xRekey)(sqlite3_pcache*, void*, unsigned oldKey, unsigned newKey);
void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
void (*xDestroy)(sqlite3_pcache*);
};
/*
** CAPI3REF: Online Backup Object
**
** The sqlite3_backup object records state information about an ongoing
** online backup operation. ^The sqlite3_backup object is created by
** a call to [sqlite3_backup_init()] and is destroyed by a call to
** [sqlite3_backup_finish()].
**
** See Also: [Using the SQLite Online Backup API]
*/
typedef struct sqlite3_backup sqlite3_backup;
/*
** CAPI3REF: Online Backup API.
**
** The backup API copies the content of one database into another.
** It is useful either for creating backups of databases or
** for copying in-memory databases to or from persistent files.
**
** See Also: [Using the SQLite Online Backup API]
**
** ^SQLite holds a write transaction open on the destination database file
** for the duration of the backup operation.
** ^The source database is read-locked only while it is being read;
** it is not locked continuously for the entire backup operation.
** ^Thus, the backup may be performed on a live source database without
** preventing other database connections from
** reading or writing to the source database while the backup is underway.
**
** ^(To perform a backup operation:
** <ol>
** <li><b>sqlite3_backup_init()</b> is called once to initialize the
** backup,
** <li><b>sqlite3_backup_step()</b> is called one or more times to transfer
** the data between the two databases, and finally
** <li><b>sqlite3_backup_finish()</b> is called to release all resources
** associated with the backup operation.
** </ol>)^
** There should be exactly one call to sqlite3_backup_finish() for each
** successful call to sqlite3_backup_init().
**
** [[sqlite3_backup_init()]] <b>sqlite3_backup_init()</b>
**
** ^The D and N arguments to sqlite3_backup_init(D,N,S,M) are the
** [database connection] associated with the destination database
** and the database name, respectively.
** ^The database name is "main" for the main database, "temp" for the
** temporary database, or the name specified after the AS keyword in
** an [ATTACH] statement for an attached database.
** ^The S and M arguments passed to
** sqlite3_backup_init(D,N,S,M) identify the [database connection]
** and database name of the source database, respectively.
** ^The source and destination [database connections] (parameters S and D)
** must be different or else sqlite3_backup_init(D,N,S,M) will fail with
** an error.
**
** ^A call to sqlite3_backup_init() will fail, returning NULL, if
** there is already a read or read-write transaction open on the
** destination database.
**
** ^If an error occurs within sqlite3_backup_init(D,N,S,M), then NULL is
** returned and an error code and error message are stored in the
** destination [database connection] D.
** ^The error code and message for the failed call to sqlite3_backup_init()
** can be retrieved using the [sqlite3_errcode()], [sqlite3_errmsg()], and/or
** [sqlite3_errmsg16()] functions.
** ^A successful call to sqlite3_backup_init() returns a pointer to an
** [sqlite3_backup] object.
** ^The [sqlite3_backup] object may be used with the sqlite3_backup_step() and
** sqlite3_backup_finish() functions to perform the specified backup
** operation.
**
** [[sqlite3_backup_step()]] <b>sqlite3_backup_step()</b>
**
** ^Function sqlite3_backup_step(B,N) will copy up to N pages between
** the source and destination databases specified by [sqlite3_backup] object B.
** ^If N is negative, all remaining source pages are copied.
** ^If sqlite3_backup_step(B,N) successfully copies N pages and there
** are still more pages to be copied, then the function returns [SQLITE_OK].
** ^If sqlite3_backup_step(B,N) successfully finishes copying all pages
** from source to destination, then it returns [SQLITE_DONE].
** ^If an error occurs while running sqlite3_backup_step(B,N),
** then an [error code] is returned. ^As well as [SQLITE_OK] and
** [SQLITE_DONE], a call to sqlite3_backup_step() may return [SQLITE_READONLY],
** [SQLITE_NOMEM], [SQLITE_BUSY], [SQLITE_LOCKED], or an
** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX] extended error code.
**
** ^(The sqlite3_backup_step() might return [SQLITE_READONLY] if
** <ol>
** <li> the destination database was opened read-only, or
** <li> the destination database is using write-ahead-log journaling
** and the destination and source page sizes differ, or
** <li> the destination database is an in-memory database and the
** destination and source page sizes differ.
** </ol>)^
**
** ^If sqlite3_backup_step() cannot obtain a required file-system lock, then
** the [sqlite3_busy_handler | busy-handler function]
** is invoked (if one is specified). ^If the
** busy-handler returns non-zero before the lock is available, then
** [SQLITE_BUSY] is returned to the caller. ^In this case the call to
** sqlite3_backup_step() can be retried later. ^If the source
** [database connection]
** is being used to write to the source database when sqlite3_backup_step()
** is called, then [SQLITE_LOCKED] is returned immediately. ^Again, in this
** case the call to sqlite3_backup_step() can be retried later on. ^(If
** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX], [SQLITE_NOMEM], or
** [SQLITE_READONLY] is returned, then
** there is no point in retrying the call to sqlite3_backup_step(). These
** errors are considered fatal.)^ The application must accept
** that the backup operation has failed and pass the backup operation handle
** to the sqlite3_backup_finish() to release associated resources.
**
** ^The first call to sqlite3_backup_step() obtains an exclusive lock
** on the destination file. ^The exclusive lock is not released until either
** sqlite3_backup_finish() is called or the backup operation is complete
** and sqlite3_backup_step() returns [SQLITE_DONE]. ^Every call to
** sqlite3_backup_step() obtains a [shared lock] on the source database that
** lasts for the duration of the sqlite3_backup_step() call.
** ^Because the source database is not locked between calls to
** sqlite3_backup_step(), the source database may be modified mid-way
** through the backup process. ^If the source database is modified by an
** external process or via a database connection other than the one being
** used by the backup operation, then the backup will be automatically
** restarted by the next call to sqlite3_backup_step(). ^If the source
** database is modified by the using the same database connection as is used
** by the backup operation, then the backup database is automatically
** updated at the same time.
**
** [[sqlite3_backup_finish()]] <b>sqlite3_backup_finish()</b>
**
** When sqlite3_backup_step() has returned [SQLITE_DONE], or when the
** application wishes to abandon the backup operation, the application
** should destroy the [sqlite3_backup] by passing it to sqlite3_backup_finish().
** ^The sqlite3_backup_finish() interfaces releases all
** resources associated with the [sqlite3_backup] object.
** ^If sqlite3_backup_step() has not yet returned [SQLITE_DONE], then any
** active write-transaction on the destination database is rolled back.
** The [sqlite3_backup] object is invalid
** and may not be used following a call to sqlite3_backup_finish().
**
** ^The value returned by sqlite3_backup_finish is [SQLITE_OK] if no
** sqlite3_backup_step() errors occurred, regardless or whether or not
** sqlite3_backup_step() completed.
** ^If an out-of-memory condition or IO error occurred during any prior
** sqlite3_backup_step() call on the same [sqlite3_backup] object, then
** sqlite3_backup_finish() returns the corresponding [error code].
**
** ^A return of [SQLITE_BUSY] or [SQLITE_LOCKED] from sqlite3_backup_step()
** is not a permanent error and does not affect the return value of
** sqlite3_backup_finish().
**
** [[sqlite3_backup_remaining()]] [[sqlite3_backup_pagecount()]]
** <b>sqlite3_backup_remaining() and sqlite3_backup_pagecount()</b>
**
** ^The sqlite3_backup_remaining() routine returns the number of pages still
** to be backed up at the conclusion of the most recent sqlite3_backup_step().
** ^The sqlite3_backup_pagecount() routine returns the total number of pages
** in the source database at the conclusion of the most recent
** sqlite3_backup_step().
** ^(The values returned by these functions are only updated by
** sqlite3_backup_step(). If the source database is modified in a way that
** changes the size of the source database or the number of pages remaining,
** those changes are not reflected in the output of sqlite3_backup_pagecount()
** and sqlite3_backup_remaining() until after the next
** sqlite3_backup_step().)^
**
** <b>Concurrent Usage of Database Handles</b>
**
** ^The source [database connection] may be used by the application for other
** purposes while a backup operation is underway or being initialized.
** ^If SQLite is compiled and configured to support threadsafe database
** connections, then the source database connection may be used concurrently
** from within other threads.
**
** However, the application must guarantee that the destination
** [database connection] is not passed to any other API (by any thread) after
** sqlite3_backup_init() is called and before the corresponding call to
** sqlite3_backup_finish(). SQLite does not currently check to see
** if the application incorrectly accesses the destination [database connection]
** and so no error code is reported, but the operations may malfunction
** nevertheless. Use of the destination database connection while a
** backup is in progress might also also cause a mutex deadlock.
**
** If running in [shared cache mode], the application must
** guarantee that the shared cache used by the destination database
** is not accessed while the backup is running. In practice this means
** that the application must guarantee that the disk file being
** backed up to is not accessed by any connection within the process,
** not just the specific connection that was passed to sqlite3_backup_init().
**
** The [sqlite3_backup] object itself is partially threadsafe. Multiple
** threads may safely make multiple concurrent calls to sqlite3_backup_step().
** However, the sqlite3_backup_remaining() and sqlite3_backup_pagecount()
** APIs are not strictly speaking threadsafe. If they are invoked at the
** same time as another thread is invoking sqlite3_backup_step() it is
** possible that they return invalid values.
*/
SQLITE_API sqlite3_backup *sqlite3_backup_init(
sqlite3 *pDest, /* Destination database handle */
const char *zDestName, /* Destination database name */
sqlite3 *pSource, /* Source database handle */
const char *zSourceName /* Source database name */
);
SQLITE_API int sqlite3_backup_step(sqlite3_backup *p, int nPage);
SQLITE_API int sqlite3_backup_finish(sqlite3_backup *p);
SQLITE_API int sqlite3_backup_remaining(sqlite3_backup *p);
SQLITE_API int sqlite3_backup_pagecount(sqlite3_backup *p);
/*
** CAPI3REF: Unlock Notification
** METHOD: sqlite3
**
** ^When running in shared-cache mode, a database operation may fail with
** an [SQLITE_LOCKED] error if the required locks on the shared-cache or
** individual tables within the shared-cache cannot be obtained. See
** [SQLite Shared-Cache Mode] for a description of shared-cache locking.
** ^This API may be used to register a callback that SQLite will invoke
** when the connection currently holding the required lock relinquishes it.
** ^This API is only available if the library was compiled with the
** [SQLITE_ENABLE_UNLOCK_NOTIFY] C-preprocessor symbol defined.
**
** See Also: [Using the SQLite Unlock Notification Feature].
**
** ^Shared-cache locks are released when a database connection concludes
** its current transaction, either by committing it or rolling it back.
**
** ^When a connection (known as the blocked connection) fails to obtain a
** shared-cache lock and SQLITE_LOCKED is returned to the caller, the
** identity of the database connection (the blocking connection) that
** has locked the required resource is stored internally. ^After an
** application receives an SQLITE_LOCKED error, it may call the
** sqlite3_unlock_notify() method with the blocked connection handle as
** the first argument to register for a callback that will be invoked
** when the blocking connections current transaction is concluded. ^The
** callback is invoked from within the [sqlite3_step] or [sqlite3_close]
** call that concludes the blocking connections transaction.
**
** ^(If sqlite3_unlock_notify() is called in a multi-threaded application,
** there is a chance that the blocking connection will have already
** concluded its transaction by the time sqlite3_unlock_notify() is invoked.
** If this happens, then the specified callback is invoked immediately,
** from within the call to sqlite3_unlock_notify().)^
**
** ^If the blocked connection is attempting to obtain a write-lock on a
** shared-cache table, and more than one other connection currently holds
** a read-lock on the same table, then SQLite arbitrarily selects one of
** the other connections to use as the blocking connection.
**
** ^(There may be at most one unlock-notify callback registered by a
** blocked connection. If sqlite3_unlock_notify() is called when the
** blocked connection already has a registered unlock-notify callback,
** then the new callback replaces the old.)^ ^If sqlite3_unlock_notify() is
** called with a NULL pointer as its second argument, then any existing
** unlock-notify callback is canceled. ^The blocked connections
** unlock-notify callback may also be canceled by closing the blocked
** connection using [sqlite3_close()].
**
** The unlock-notify callback is not reentrant. If an application invokes
** any sqlite3_xxx API functions from within an unlock-notify callback, a
** crash or deadlock may be the result.
**
** ^Unless deadlock is detected (see below), sqlite3_unlock_notify() always
** returns SQLITE_OK.
**
** <b>Callback Invocation Details</b>
**
** When an unlock-notify callback is registered, the application provides a
** single void* pointer that is passed to the callback when it is invoked.
** However, the signature of the callback function allows SQLite to pass
** it an array of void* context pointers. The first argument passed to
** an unlock-notify callback is a pointer to an array of void* pointers,
** and the second is the number of entries in the array.
**
** When a blocking connections transaction is concluded, there may be
** more than one blocked connection that has registered for an unlock-notify
** callback. ^If two or more such blocked connections have specified the
** same callback function, then instead of invoking the callback function
** multiple times, it is invoked once with the set of void* context pointers
** specified by the blocked connections bundled together into an array.
** This gives the application an opportunity to prioritize any actions
** related to the set of unblocked database connections.
**
** <b>Deadlock Detection</b>
**
** Assuming that after registering for an unlock-notify callback a
** database waits for the callback to be issued before taking any further
** action (a reasonable assumption), then using this API may cause the
** application to deadlock. For example, if connection X is waiting for
** connection Y's transaction to be concluded, and similarly connection
** Y is waiting on connection X's transaction, then neither connection
** will proceed and the system may remain deadlocked indefinitely.
**
** To avoid this scenario, the sqlite3_unlock_notify() performs deadlock
** detection. ^If a given call to sqlite3_unlock_notify() would put the
** system in a deadlocked state, then SQLITE_LOCKED is returned and no
** unlock-notify callback is registered. The system is said to be in
** a deadlocked state if connection A has registered for an unlock-notify
** callback on the conclusion of connection B's transaction, and connection
** B has itself registered for an unlock-notify callback when connection
** A's transaction is concluded. ^Indirect deadlock is also detected, so
** the system is also considered to be deadlocked if connection B has
** registered for an unlock-notify callback on the conclusion of connection
** C's transaction, where connection C is waiting on connection A. ^Any
** number of levels of indirection are allowed.
**
** <b>The "DROP TABLE" Exception</b>
**
** When a call to [sqlite3_step()] returns SQLITE_LOCKED, it is almost
** always appropriate to call sqlite3_unlock_notify(). There is however,
** one exception. When executing a "DROP TABLE" or "DROP INDEX" statement,
** SQLite checks if there are any currently executing SELECT statements
** that belong to the same connection. If there are, SQLITE_LOCKED is
** returned. In this case there is no "blocking connection", so invoking
** sqlite3_unlock_notify() results in the unlock-notify callback being
** invoked immediately. If the application then re-attempts the "DROP TABLE"
** or "DROP INDEX" query, an infinite loop might be the result.
**
** One way around this problem is to check the extended error code returned
** by an sqlite3_step() call. ^(If there is a blocking connection, then the
** extended error code is set to SQLITE_LOCKED_SHAREDCACHE. Otherwise, in
** the special "DROP TABLE/INDEX" case, the extended error code is just
** SQLITE_LOCKED.)^
*/
SQLITE_API int sqlite3_unlock_notify(
sqlite3 *pBlocked, /* Waiting connection */
void (*xNotify)(void **apArg, int nArg), /* Callback function to invoke */
void *pNotifyArg /* Argument to pass to xNotify */
);
/*
** CAPI3REF: String Comparison
**
** ^The [sqlite3_stricmp()] and [sqlite3_strnicmp()] APIs allow applications
** and extensions to compare the contents of two buffers containing UTF-8
** strings in a case-independent fashion, using the same definition of "case
** independence" that SQLite uses internally when comparing identifiers.
*/
SQLITE_API int sqlite3_stricmp(const char *, const char *);
SQLITE_API int sqlite3_strnicmp(const char *, const char *, int);
/*
** CAPI3REF: String Globbing
*
** ^The [sqlite3_strglob(P,X)] interface returns zero if and only if
** string X matches the [GLOB] pattern P.
** ^The definition of [GLOB] pattern matching used in
** [sqlite3_strglob(P,X)] is the same as for the "X GLOB P" operator in the
** SQL dialect understood by SQLite. ^The [sqlite3_strglob(P,X)] function
** is case sensitive.
**
** Note that this routine returns zero on a match and non-zero if the strings
** do not match, the same as [sqlite3_stricmp()] and [sqlite3_strnicmp()].
**
** See also: [sqlite3_strlike()].
*/
SQLITE_API int sqlite3_strglob(const char *zGlob, const char *zStr);
/*
** CAPI3REF: String LIKE Matching
*
** ^The [sqlite3_strlike(P,X,E)] interface returns zero if and only if
** string X matches the [LIKE] pattern P with escape character E.
** ^The definition of [LIKE] pattern matching used in
** [sqlite3_strlike(P,X,E)] is the same as for the "X LIKE P ESCAPE E"
** operator in the SQL dialect understood by SQLite. ^For "X LIKE P" without
** the ESCAPE clause, set the E parameter of [sqlite3_strlike(P,X,E)] to 0.
** ^As with the LIKE operator, the [sqlite3_strlike(P,X,E)] function is case
** insensitive - equivalent upper and lower case ASCII characters match
** one another.
**
** ^The [sqlite3_strlike(P,X,E)] function matches Unicode characters, though
** only ASCII characters are case folded.
**
** Note that this routine returns zero on a match and non-zero if the strings
** do not match, the same as [sqlite3_stricmp()] and [sqlite3_strnicmp()].
**
** See also: [sqlite3_strglob()].
*/
SQLITE_API int sqlite3_strlike(const char *zGlob, const char *zStr, unsigned int cEsc);
/*
** CAPI3REF: Error Logging Interface
**
** ^The [sqlite3_log()] interface writes a message into the [error log]
void (*xPreUpdateCallback)( /* Registered using sqlite3_preupdate_hook() */
void*,sqlite3*,int,char const*,char const*,sqlite3_int64,sqlite3_int64
);
PreUpdate *pPreUpdate; /* Context for active pre-update callback */
#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
#ifndef SQLITE_OMIT_WAL
int (*xWalCallback)(void *, sqlite3 *, const char *, int);
void *pWalArg;
#endif
void(*xCollNeeded)(void*,sqlite3*,int eTextRep,const char*);
void(*xCollNeeded16)(void*,sqlite3*,int eTextRep,const void*);
void *pCollNeededArg;
sqlite3_value *pErr; /* Most recent error message */
union {
volatile int isInterrupted; /* True if sqlite3_interrupt has been called */
double notUsed1; /* Spacer */
} u1;
Lookaside lookaside; /* Lookaside malloc configuration */
#ifndef SQLITE_OMIT_AUTHORIZATION
sqlite3_xauth xAuth; /* Access authorization function */
void *pAuthArg; /* 1st argument to the access auth function */
#endif
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
int (*xProgress)(void *); /* The progress callback */
void *pProgressArg; /* Argument to the progress callback */
unsigned nProgressOps; /* Number of opcodes for progress callback */
#endif
#ifndef SQLITE_OMIT_VIRTUALTABLE
int nVTrans; /* Allocated size of aVTrans */
Hash aModule; /* populated by sqlite3_create_module() */
VtabCtx *pVtabCtx; /* Context for active vtab connect/create */
VTable **aVTrans; /* Virtual tables with open transactions */
VTable *pDisconnect; /* Disconnect these in next sqlite3_prepare() */
#endif
Hash aFunc; /* Hash table of connection functions */
Hash aCollSeq; /* All collating sequences */
BusyHandler busyHandler; /* Busy callback */
Db aDbStatic[2]; /* Static space for the 2 default backends */
Savepoint *pSavepoint; /* List of active savepoints */
int busyTimeout; /* Busy handler timeout, in msec */
int nSavepoint; /* Number of non-transaction savepoints */
int nStatement; /* Number of nested statement-transactions */
i64 nDeferredCons; /* Net deferred constraints this transaction. */
i64 nDeferredImmCons; /* Net deferred immediate constraints */
int *pnBytesFreed; /* If not NULL, increment this in DbFree() */
#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
/* The following variables are all protected by the STATIC_MASTER
** mutex, not by sqlite3.mutex. They are used by code in notify.c.
**
** When X.pUnlockConnection==Y, that means that X is waiting for Y to
** unlock so that it can proceed.
**
** When X.pBlockingConnection==Y, that means that something that X tried
** tried to do recently failed with an SQLITE_LOCKED error due to locks
** held by Y.
*/
sqlite3 *pBlockingConnection; /* Connection that caused SQLITE_LOCKED */
sqlite3 *pUnlockConnection; /* Connection to watch for unlock */
void *pUnlockArg; /* Argument to xUnlockNotify */
void (*xUnlockNotify)(void **, int); /* Unlock notify callback */
sqlite3 *pNextBlocked; /* Next in list of all blocked connections */
#endif
#ifdef SQLITE_USER_AUTHENTICATION
sqlite3_userauth auth; /* User authentication information */
#endif
};
/*
** A macro to discover the encoding of a database.
*/
#define SCHEMA_ENC(db) ((db)->aDb[0].pSchema->enc)
#define ENC(db) ((db)->enc)
/*
** Possible values for the sqlite3.flags.
**
** Value constraints (enforced via assert()):
** SQLITE_FullFSync == PAGER_FULLFSYNC
** SQLITE_CkptFullFSync == PAGER_CKPT_FULLFSYNC
** SQLITE_CacheSpill == PAGER_CACHE_SPILL
*/
#define SQLITE_WriteSchema 0x00000001 /* OK to update SQLITE_MASTER */
#define SQLITE_LegacyFileFmt 0x00000002 /* Create new databases in format 1 */
#define SQLITE_FullColNames 0x00000004 /* Show full column names on SELECT */
#define SQLITE_FullFSync 0x00000008 /* Use full fsync on the backend */
#define SQLITE_CkptFullFSync 0x00000010 /* Use full fsync for checkpoint */
#define SQLITE_CacheSpill 0x00000020 /* OK to spill pager cache */
#define SQLITE_ShortColNames 0x00000040 /* Show short columns names */
#define SQLITE_CountRows 0x00000080 /* Count rows changed by INSERT, */
/* DELETE, or UPDATE and return */
/* the count using a callback. */
#define SQLITE_NullCallback 0x00000100 /* Invoke the callback once if the */
/* result set is empty */
#define SQLITE_IgnoreChecks 0x00000200 /* Do not enforce check constraints */
#define SQLITE_ReadUncommit 0x00000400 /* READ UNCOMMITTED in shared-cache */
#define SQLITE_NoCkptOnClose 0x00000800 /* No checkpoint on close()/DETACH */
#define SQLITE_ReverseOrder 0x00001000 /* Reverse unordered SELECTs */
#define SQLITE_RecTriggers 0x00002000 /* Enable recursive triggers */
#define SQLITE_ForeignKeys 0x00004000 /* Enforce foreign key constraints */
#define SQLITE_AutoIndex 0x00008000 /* Enable automatic indexes */
#define SQLITE_LoadExtension 0x00010000 /* Enable load_extension */
#define SQLITE_LoadExtFunc 0x00020000 /* Enable load_extension() SQL func */
#define SQLITE_EnableTrigger 0x00040000 /* True to enable triggers */
#define SQLITE_DeferFKs 0x00080000 /* Defer all FK constraints */
#define SQLITE_QueryOnly 0x00100000 /* Disable database changes */
#define SQLITE_CellSizeCk 0x00200000 /* Check btree cell sizes on load */
#define SQLITE_Fts3Tokenizer 0x00400000 /* Enable fts3_tokenizer(2) */
#define SQLITE_EnableQPSG 0x00800000 /* Query Planner Stability Guarantee*/
#define SQLITE_TriggerEQP 0x01000000 /* Show trigger EXPLAIN QUERY PLAN */
#define SQLITE_ResetDatabase 0x02000000 /* Reset the database */
#define SQLITE_LegacyAlter 0x04000000 /* Legacy ALTER TABLE behaviour */
#define SQLITE_NoSchemaError 0x08000000 /* Do not report schema parse errors*/
#define SQLITE_Defensive 0x10000000 /* Input SQL is likely hostile */
/* Flags used only if debugging */
#define HI(X) ((u64)(X)<<32)
#ifdef SQLITE_DEBUG
#define SQLITE_SqlTrace HI(0x0001) /* Debug print SQL as it executes */
#define SQLITE_VdbeListing HI(0x0002) /* Debug listings of VDBE progs */
#define SQLITE_VdbeTrace HI(0x0004) /* True to trace VDBE execution */
#define SQLITE_VdbeAddopTrace HI(0x0008) /* Trace sqlite3VdbeAddOp() calls */
/*
** Available fault injectors. Should be numbered beginning with 0.
*/
#define SQLITE_FAULTINJECTOR_MALLOC 0
#define SQLITE_FAULTINJECTOR_COUNT 1
/*
** The interface to the code in fault.c used for identifying "benign"
** malloc failures. This is only present if SQLITE_UNTESTABLE
** is not defined.
*/
#ifndef SQLITE_UNTESTABLE
SQLITE_PRIVATE void sqlite3BeginBenignMalloc(void);
SQLITE_PRIVATE void sqlite3EndBenignMalloc(void);
#else
#define sqlite3BeginBenignMalloc()
#define sqlite3EndBenignMalloc()
#endif
/*
** Allowed return values from sqlite3FindInIndex()
*/
#define IN_INDEX_ROWID 1 /* Search the rowid of the table */
#define IN_INDEX_EPH 2 /* Search an ephemeral b-tree */
#define IN_INDEX_INDEX_ASC 3 /* Existing index ASCENDING */
#define IN_INDEX_INDEX_DESC 4 /* Existing index DESCENDING */
#define IN_INDEX_NOOP 5 /* No table available. Use comparisons */
/*
** Allowed flags for the 3rd parameter to sqlite3FindInIndex().
*/
#define IN_INDEX_NOOP_OK 0x0001 /* OK to return IN_INDEX_NOOP */
#define IN_INDEX_MEMBERSHIP 0x0002 /* IN operator used for membership test */
#define IN_INDEX_LOOP 0x0004 /* IN operator used as a loop */
SQLITE_PRIVATE int sqlite3FindInIndex(Parse *, Expr *, u32, int*, int*);
SQLITE_PRIVATE int sqlite3JournalOpen(sqlite3_vfs *, const char *, sqlite3_file *, int, int);
SQLITE_PRIVATE int sqlite3JournalSize(sqlite3_vfs *);
#if defined(SQLITE_ENABLE_ATOMIC_WRITE) \
|| defined(SQLITE_ENABLE_BATCH_ATOMIC_WRITE)
SQLITE_PRIVATE int sqlite3JournalCreate(sqlite3_file *);
#endif
SQLITE_PRIVATE int sqlite3JournalIsInMemory(sqlite3_file *p);
SQLITE_PRIVATE void sqlite3MemJournalOpen(sqlite3_file *);
SQLITE_PRIVATE void sqlite3ExprSetHeightAndFlags(Parse *pParse, Expr *p);
#if SQLITE_MAX_EXPR_DEPTH>0
SQLITE_PRIVATE int sqlite3SelectExprHeight(Select *);
SQLITE_PRIVATE int sqlite3ExprCheckHeight(Parse*, int);
#else
#define sqlite3SelectExprHeight(x) 0
#define sqlite3ExprCheckHeight(x,y)
#endif
SQLITE_PRIVATE u32 sqlite3Get4byte(const u8*);
SQLITE_PRIVATE void sqlite3Put4byte(u8*, u32);
#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
SQLITE_PRIVATE void sqlite3ConnectionBlocked(sqlite3 *, sqlite3 *);
SQLITE_PRIVATE void sqlite3ConnectionUnlocked(sqlite3 *db);
SQLITE_PRIVATE void sqlite3ConnectionClosed(sqlite3 *db);
#else
#define sqlite3ConnectionBlocked(x,y)
#define sqlite3ConnectionUnlocked(x)
#define sqlite3ConnectionClosed(x)
#endif
#ifdef SQLITE_DEBUG
SQLITE_PRIVATE void sqlite3ParserTrace(FILE*, char *);
#endif
#if defined(YYCOVERAGE)
SQLITE_PRIVATE int sqlite3ParserCoverage(FILE*);
#endif
/*
** If the SQLITE_ENABLE IOTRACE exists then the global variable
** sqlite3IoTrace is a pointer to a printf-like routine used to
** print I/O tracing messages.
*/
#ifdef SQLITE_ENABLE_IOTRACE
# define IOTRACE(A) if( sqlite3IoTrace ){ sqlite3IoTrace A; }
SQLITE_PRIVATE void sqlite3VdbeIOTraceSql(Vdbe*);
SQLITE_API SQLITE_EXTERN void (SQLITE_CDECL *sqlite3IoTrace)(const char*,...);
#else
# define IOTRACE(A)
# define sqlite3VdbeIOTraceSql(X)
#endif
/*
** These routines are available for the mem2.c debugging memory allocator
** only. They are used to verify that different "types" of memory
** allocations are properly tracked by the system.
**
** sqlite3MemdebugSetType() sets the "type" of an allocation to one of
** the MEMTYPE_* macros defined below. The type must be a bitmask with
** a single bit set.
**
** sqlite3MemdebugHasType() returns true if any of the bits in its second
** argument match the type set by the previous sqlite3MemdebugSetType().
** sqlite3MemdebugHasType() is intended for use inside assert() statements.
**
** sqlite3MemdebugNoType() returns true if none of the bits in its second
** argument match the type set by the previous sqlite3MemdebugSetType().
**
** Perhaps the most important point is the difference between MEMTYPE_HEAP
** and MEMTYPE_LOOKASIDE. If an allocation is MEMTYPE_LOOKASIDE, that means
** it might have been allocated by lookaside, except the allocation was
** too large or lookaside was already full. It is important to verify
** that allocations that might have been satisfied by lookaside are not
** passed back to non-lookaside free() routines. Asserts such as the
** example above are placed on the non-lookaside free() routines to verify
** this constraint.
**
** All of this is no-op for a production build. It only comes into
** play when the SQLITE_MEMDEBUG compile-time option is used.
*/
#ifdef SQLITE_MEMDEBUG
SQLITE_PRIVATE void sqlite3MemdebugSetType(void*,u8);
SQLITE_PRIVATE int sqlite3MemdebugHasType(void*,u8);
SQLITE_PRIVATE int sqlite3MemdebugNoType(void*,u8);
#else
# define sqlite3MemdebugSetType(X,Y) /* no-op */
# define sqlite3MemdebugHasType(X,Y) 1
# define sqlite3MemdebugNoType(X,Y) 1
SQLITE_PRIVATE int sqlite3OsDeviceCharacteristics(sqlite3_file *id){
return id->pMethods->xDeviceCharacteristics(id);
}
#ifndef SQLITE_OMIT_WAL
SQLITE_PRIVATE int sqlite3OsShmLock(sqlite3_file *id, int offset, int n, int flags){
return id->pMethods->xShmLock(id, offset, n, flags);
}
SQLITE_PRIVATE void sqlite3OsShmBarrier(sqlite3_file *id){
id->pMethods->xShmBarrier(id);
}
SQLITE_PRIVATE int sqlite3OsShmUnmap(sqlite3_file *id, int deleteFlag){
return id->pMethods->xShmUnmap(id, deleteFlag);
}
SQLITE_PRIVATE int sqlite3OsShmMap(
sqlite3_file *id, /* Database file handle */
int iPage,
int pgsz,
int bExtend, /* True to extend file if necessary */
void volatile **pp /* OUT: Pointer to mapping */
){
DO_OS_MALLOC_TEST(id);
return id->pMethods->xShmMap(id, iPage, pgsz, bExtend, pp);
}
#endif /* SQLITE_OMIT_WAL */
#if SQLITE_MAX_MMAP_SIZE>0
/* The real implementation of xFetch and xUnfetch */
SQLITE_PRIVATE int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
DO_OS_MALLOC_TEST(id);
return id->pMethods->xFetch(id, iOff, iAmt, pp);
}
SQLITE_PRIVATE int sqlite3OsUnfetch(sqlite3_file *id, i64 iOff, void *p){
return id->pMethods->xUnfetch(id, iOff, p);
}
#else
/* No-op stubs to use when memory-mapped I/O is disabled */
SQLITE_PRIVATE int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
*pp = 0;
return SQLITE_OK;
}
SQLITE_PRIVATE int sqlite3OsUnfetch(sqlite3_file *id, i64 iOff, void *p){
return SQLITE_OK;
}
#endif
/*
** The next group of routines are convenience wrappers around the
** VFS methods.
*/
SQLITE_PRIVATE int sqlite3OsOpen(
sqlite3_vfs *pVfs,
const char *zPath,
sqlite3_file *pFile,
int flags,
int *pFlagsOut
){
int rc;
DO_OS_MALLOC_TEST(0);
/* 0x87f7f is a mask of SQLITE_OPEN_ flags that are valid to be passed
** down into the VFS layer. Some SQLITE_OPEN_ flags (for example,
** SQLITE_OPEN_FULLMUTEX or SQLITE_OPEN_SHAREDCACHE) are blocked before
** reaching the VFS. */
rc = pVfs->xOpen(pVfs, zPath, pFile, flags & 0x87f7f, pFlagsOut);
assert( rc==SQLITE_OK || pFile->pMethods==0 );
return rc;
}
SQLITE_PRIVATE int sqlite3OsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
DO_OS_MALLOC_TEST(0);
assert( dirSync==0 || dirSync==1 );
return pVfs->xDelete(pVfs, zPath, dirSync);
}
SQLITE_PRIVATE int sqlite3OsAccess(
sqlite3_vfs *pVfs,
const char *zPath,
int flags,
int *pResOut
){
DO_OS_MALLOC_TEST(0);
return pVfs->xAccess(pVfs, zPath, flags, pResOut);
}
SQLITE_PRIVATE int sqlite3OsFullPathname(
sqlite3_vfs *pVfs,
const char *zPath,
int nPathOut,
char *zPathOut
){
DO_OS_MALLOC_TEST(0);
zPathOut[0] = 0;
return pVfs->xFullPathname(pVfs, zPath, nPathOut, zPathOut);
}
#ifndef SQLITE_OMIT_LOAD_EXTENSION
SQLITE_PRIVATE void *sqlite3OsDlOpen(sqlite3_vfs *pVfs, const char *zPath){
return pVfs->xDlOpen(pVfs, zPath);
}
SQLITE_PRIVATE void sqlite3OsDlError(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
pVfs->xDlError(pVfs, nByte, zBufOut);
}
SQLITE_PRIVATE void (*sqlite3OsDlSym(sqlite3_vfs *pVfs, void *pHdle, const char *zSym))(void){
return pVfs->xDlSym(pVfs, pHdle, zSym);
}
SQLITE_PRIVATE void sqlite3OsDlClose(sqlite3_vfs *pVfs, void *pHandle){
pVfs->xDlClose(pVfs, pHandle);
}
#endif /* SQLITE_OMIT_LOAD_EXTENSION */
SQLITE_PRIVATE int sqlite3OsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
return pVfs->xRandomness(pVfs, nByte, zBufOut);
}
SQLITE_PRIVATE int sqlite3OsSleep(sqlite3_vfs *pVfs, int nMicro){
return pVfs->xSleep(pVfs, nMicro);
}
SQLITE_PRIVATE int sqlite3OsGetLastError(sqlite3_vfs *pVfs){
return pVfs->xGetLastError ? pVfs->xGetLastError(pVfs, 0, 0) : 0;
}
SQLITE_PRIVATE int sqlite3OsCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *pTimeOut){
int rc;
/* IMPLEMENTATION-OF: R-49045-42493 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.
*/
#ifdef SQLITE_DEBUG
/*
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
** intended for use only inside assert() statements.
*/
static int winMutexHeld(sqlite3_mutex *p){
return p->nRef!=0 && p->owner==GetCurrentThreadId();
}
static int winMutexNotheld2(sqlite3_mutex *p, DWORD tid){
return p->nRef==0 || p->owner!=tid;
}
static int winMutexNotheld(sqlite3_mutex *p){
DWORD tid = GetCurrentThreadId();
return winMutexNotheld2(p, tid);
}
#endif
/*
** Try to provide a memory barrier operation, needed for initialization
** and also for the xShmBarrier method of the VFS in cases when SQLite is
** compiled without mutexes (SQLITE_THREADSAFE=0).
*/
SQLITE_PRIVATE void sqlite3MemoryBarrier(void){
#if defined(SQLITE_MEMORY_BARRIER)
SQLITE_MEMORY_BARRIER;
#elif defined(__GNUC__)
__sync_synchronize();
#elif MSVC_VERSION>=1300
_ReadWriteBarrier();
#elif defined(MemoryBarrier)
MemoryBarrier();
#endif
}
/*
** Initialize and deinitialize the mutex subsystem.
*/
static sqlite3_mutex winMutex_staticMutexes[] = {
SQLITE3_MUTEX_INITIALIZER(2),
SQLITE3_MUTEX_INITIALIZER(3),
SQLITE3_MUTEX_INITIALIZER(4),
SQLITE3_MUTEX_INITIALIZER(5),
SQLITE3_MUTEX_INITIALIZER(6),
SQLITE3_MUTEX_INITIALIZER(7),
SQLITE3_MUTEX_INITIALIZER(8),
SQLITE3_MUTEX_INITIALIZER(9),
SQLITE3_MUTEX_INITIALIZER(10),
SQLITE3_MUTEX_INITIALIZER(11),
SQLITE3_MUTEX_INITIALIZER(12),
SQLITE3_MUTEX_INITIALIZER(13)
};
static int winMutex_isInit = 0;
static int winMutex_isNt = -1; /* <0 means "need to query" */
/* As the winMutexInit() and winMutexEnd() functions are called as part
** of the sqlite3_initialize() and sqlite3_shutdown() processing, the
** "interlocked" magic used here is probably not strictly necessary.
*/
static LONG SQLITE_WIN32_VOLATILE winMutex_lock = 0;
SQLITE_API int sqlite3_win32_is_nt(void); /* os_win.c */
SQLITE_API void sqlite3_win32_sleep(DWORD milliseconds); /* os_win.c */
static int winMutexInit(void){
/* The first to increment to 1 does actual initialization */
if( InterlockedCompareExchange(&winMutex_lock, 1, 0)==0 ){
int i;
for(i=0; i<ArraySize(winMutex_staticMutexes); i++){
#if SQLITE_OS_WINRT
InitializeCriticalSectionEx(&winMutex_staticMutexes[i].mutex, 0, 0);
#else
InitializeCriticalSection(&winMutex_staticMutexes[i].mutex);
#endif
}
winMutex_isInit = 1;
}else{
/* Another thread is (in the process of) initializing the static
** mutexes */
while( !winMutex_isInit ){
sqlite3_win32_sleep(1);
}
}
return SQLITE_OK;
}
static int winMutexEnd(void){
/* The first to decrement to 0 does actual shutdown
** (which should be the last to shutdown.) */
if( InterlockedCompareExchange(&winMutex_lock, 0, 1)==1 ){
if( winMutex_isInit==1 ){
int i;
for(i=0; i<ArraySize(winMutex_staticMutexes); i++){
DeleteCriticalSection(&winMutex_staticMutexes[i].mutex);
}
winMutex_isInit = 0;
}
}
return SQLITE_OK;
}
/*
** The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it. If it returns NULL
** that means that a mutex could not be allocated. SQLite
** will unwind its stack and return an error. The argument
** to sqlite3_mutex_alloc() is one of these integer constants:
**
** <ul>
** <li> SQLITE_MUTEX_FAST
** <li> SQLITE_MUTEX_RECURSIVE
** <li> SQLITE_MUTEX_STATIC_MASTER
** <li> SQLITE_MUTEX_STATIC_MEM
** <li> SQLITE_MUTEX_STATIC_OPEN
** <li> SQLITE_MUTEX_STATIC_PRNG
** <li> SQLITE_MUTEX_STATIC_LRU
** <li> SQLITE_MUTEX_STATIC_PMEM
** <li> SQLITE_MUTEX_STATIC_APP1
** <li> SQLITE_MUTEX_STATIC_APP2
** <li> SQLITE_MUTEX_STATIC_APP3
** <li> SQLITE_MUTEX_STATIC_VFS1
** <li> SQLITE_MUTEX_STATIC_VFS2
** <li> SQLITE_MUTEX_STATIC_VFS3
** </ul>
**
** The first two constants cause sqlite3_mutex_alloc() to create
** a new mutex. The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
** The mutex implementation does not need to make a distinction
** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
** not want to. But SQLite will only request a recursive mutex in
** cases where it really needs one. If a faster non-recursive mutex
** implementation is available on the host platform, the mutex subsystem
** might return such a mutex in response to SQLITE_MUTEX_FAST.
**
** The other allowed parameters to sqlite3_mutex_alloc() each return
** a pointer to a static preexisting mutex. Six static mutexes are
** used by the current version of SQLite. Future versions of SQLite
** may add additional static mutexes. Static mutexes are for internal
** use by SQLite only. Applications that use SQLite mutexes should
** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
** SQLITE_MUTEX_RECURSIVE.
**
** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
** returns a different mutex on every call. But for the static
** mutex types, the same mutex is returned on every call that has
** the same type number.
*/
static sqlite3_mutex *winMutexAlloc(int iType){
sqlite3_mutex *p;
switch( iType ){
case SQLITE_MUTEX_FAST:
case SQLITE_MUTEX_RECURSIVE: {
p = sqlite3MallocZero( sizeof(*p) );
if( p ){
p->id = iType;
#ifdef SQLITE_DEBUG
#ifdef SQLITE_WIN32_MUTEX_TRACE_DYNAMIC
p->trace = 1;
#endif
#endif
#if SQLITE_OS_WINRT
InitializeCriticalSectionEx(&p->mutex, 0, 0);
#else
InitializeCriticalSection(&p->mutex);
#endif
}
break;
}
default: {
#ifdef SQLITE_ENABLE_API_ARMOR
if( iType-2<0 || iType-2>=ArraySize(winMutex_staticMutexes) ){
(void)SQLITE_MISUSE_BKPT;
return 0;
}
#endif
p = &winMutex_staticMutexes[iType-2];
#ifdef SQLITE_DEBUG
#ifdef SQLITE_WIN32_MUTEX_TRACE_STATIC
InterlockedCompareExchange(&p->trace, 1, 0);
#endif
#endif
break;
}
}
assert( p==0 || p->id==iType );
return p;
}
/*
** This routine deallocates a previously
** allocated mutex. SQLite is careful to deallocate every
** mutex that it allocates.
*/
static void winMutexFree(sqlite3_mutex *p){
assert( p );
assert( p->nRef==0 && p->owner==0 );
if( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE ){
DeleteCriticalSection(&p->mutex);
sqlite3_free(p);
}else{
#ifdef SQLITE_ENABLE_API_ARMOR
(void)SQLITE_MISUSE_BKPT;
#endif
}
}
/*
** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
** to enter a mutex. If another thread is already within the mutex,
** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
** SQLITE_BUSY. The sqlite3_mutex_try() interface returns SQLITE_OK
** upon successful entry. Mutexes created using SQLITE_MUTEX_RECURSIVE can
** be entered multiple times by the same thread. In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter. If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
static void winMutexEnter(sqlite3_mutex *p){
#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
DWORD tid = GetCurrentThreadId();
#endif
#ifdef SQLITE_DEBUG
assert( p );
assert( p->id==SQLITE_MUTEX_RECURSIVE || winMutexNotheld2(p, tid) );
#else
assert( p );
#endif
assert( winMutex_isInit==1 );
EnterCriticalSection(&p->mutex);
#ifdef SQLITE_DEBUG
assert( p->nRef>0 || p->owner==0 );
p->owner = tid;
p->nRef++;
if( p->trace ){
OSTRACE(("ENTER-MUTEX tid=%lu, mutex(%d)=%p (%d), nRef=%d\n",
tid, p->id, p, p->trace, p->nRef));
}
#endif
for(pp=&vxworksFileList; *pp && *pp!=pId; pp = &((*pp)->pNext)){}
assert( *pp==pId );
*pp = pId->pNext;
sqlite3_free(pId);
}
unixLeaveMutex();
}
#endif /* OS_VXWORKS */
/*************** End of Unique File ID Utility Used By VxWorks ****************
******************************************************************************/
/******************************************************************************
*************************** Posix Advisory Locking ****************************
**
** POSIX advisory locks are broken by design. ANSI STD 1003.1 (1996)
** section 6.5.2.2 lines 483 through 490 specify that when a process
** sets or clears a lock, that operation overrides any prior locks set
** by the same process. It does not explicitly say so, but this implies
** that it overrides locks set by the same process using a different
** file descriptor. Consider this test case:
**
** int fd1 = open("./file1", O_RDWR|O_CREAT, 0644);
** int fd2 = open("./file2", O_RDWR|O_CREAT, 0644);
**
** Suppose ./file1 and ./file2 are really the same file (because
** one is a hard or symbolic link to the other) then if you set
** an exclusive lock on fd1, then try to get an exclusive lock
** on fd2, it works. I would have expected the second lock to
** fail since there was already a lock on the file due to fd1.
** But not so. Since both locks came from the same process, the
** second overrides the first, even though they were on different
** file descriptors opened on different file names.
**
** This means that we cannot use POSIX locks to synchronize file access
** among competing threads of the same process. POSIX locks will work fine
** to synchronize access for threads in separate processes, but not
** threads within the same process.
**
** To work around the problem, SQLite has to manage file locks internally
** on its own. Whenever a new database is opened, we have to find the
** specific inode of the database file (the inode is determined by the
** st_dev and st_ino fields of the stat structure that fstat() fills in)
** and check for locks already existing on that inode. When locks are
** created or removed, we have to look at our own internal record of the
** locks to see if another thread has previously set a lock on that same
** inode.
**
** (Aside: The use of inode numbers as unique IDs does not work on VxWorks.
** For VxWorks, we have to use the alternative unique ID system based on
** canonical filename and implemented in the previous division.)
**
** The sqlite3_file structure for POSIX is no longer just an integer file
** descriptor. It is now a structure that holds the integer file
** descriptor and a pointer to a structure that describes the internal
** locks on the corresponding inode. There is one locking structure
** per inode, so if the same inode is opened twice, both unixFile structures
** point to the same locking structure. The locking structure keeps
** a reference count (so we will know when to delete it) and a "cnt"
** field that tells us its internal lock status. cnt==0 means the
** file is unlocked. cnt==-1 means the file has an exclusive lock.
** cnt>0 means there are cnt shared locks on the file.
**
** Any attempt to lock or unlock a file first checks the locking
** structure. The fcntl() system call is only invoked to set a
** POSIX lock if the internal lock structure transitions between
** a locked and an unlocked state.
**
** But wait: there are yet more problems with POSIX advisory locks.
**
** If you close a file descriptor that points to a file that has locks,
** all locks on that file that are owned by the current process are
** released. To work around this problem, each unixInodeInfo object
** maintains a count of the number of pending locks on tha inode.
** When an attempt is made to close an unixFile, if there are
** other unixFile open on the same inode that are holding locks, the call
** to close() the file descriptor is deferred until all of the locks clear.
** The unixInodeInfo structure keeps a list of file descriptors that need to
** be closed and that list is walked (and cleared) when the last lock
** clears.
**
** Yet another problem: LinuxThreads do not play well with posix locks.
**
** Many older versions of linux use the LinuxThreads library which is
** not posix compliant. Under LinuxThreads, a lock created by thread
** A cannot be modified or overridden by a different thread B.
** Only thread A can modify the lock. Locking behavior is correct
** if the appliation uses the newer Native Posix Thread Library (NPTL)
** on linux - with NPTL a lock created by thread A can override locks
** in thread B. But there is no way to know at compile-time which
** threading library is being used. So there is no way to know at
** compile-time whether or not thread A can override locks on thread B.
** One has to do a run-time check to discover the behavior of the
** current process.
**
** SQLite used to support LinuxThreads. But support for LinuxThreads
** was dropped beginning with version 3.7.0. SQLite will still work with
** LinuxThreads provided that (1) there is no more than one connection
** per database file in the same process and (2) database connections
** do not move across threads.
*/
/*
** An instance of the following structure serves as the key used
** to locate a particular unixInodeInfo object.
*/
struct unixFileId {
dev_t dev; /* Device number */
#if OS_VXWORKS
struct vxworksFileId *pId; /* Unique file ID for vxworks. */
#else
/* We are told that some versions of Android contain a bug that
** sizes ino_t at only 32-bits instead of 64-bits. (See
** https://android-review.googlesource.com/#/c/115351/3/dist/sqlite3.c)
** To work around this, always allocate 64-bits for the inode number.
** On small machines that only have 32-bit inodes, this wastes 4 bytes,
** but that should not be a big deal. */
/* WAS: ino_t ino; */
u64 ino; /* Inode number */
#endif
};
/*
** An instance of the following structure is allocated for each open
** inode.
**
** A single inode can have multiple file descriptors, so each unixFile
assert( pInode!=0 );
assert( sqlite3_mutex_held(pInode->pLockMutex) );
if( (pFile->ctrlFlags & (UNIXFILE_EXCL|UNIXFILE_RDONLY))==UNIXFILE_EXCL ){
if( pInode->bProcessLock==0 ){
struct flock lock;
assert( pInode->nLock==0 );
lock.l_whence = SEEK_SET;
lock.l_start = SHARED_FIRST;
lock.l_len = SHARED_SIZE;
lock.l_type = F_WRLCK;
rc = osSetPosixAdvisoryLock(pFile->h, &lock, pFile);
if( rc<0 ) return rc;
pInode->bProcessLock = 1;
pInode->nLock++;
}else{
rc = 0;
}
}else{
rc = osSetPosixAdvisoryLock(pFile->h, pLock, pFile);
}
return rc;
}
/*
** Lock the file with the lock specified by parameter eFileLock - one
** of the following:
**
** (1) SHARED_LOCK
** (2) RESERVED_LOCK
** (3) PENDING_LOCK
** (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between. The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal. The following chart shows the allowed
** transitions and the inserted intermediate states:
**
** UNLOCKED -> SHARED
** SHARED -> RESERVED
** SHARED -> (PENDING) -> EXCLUSIVE
** RESERVED -> (PENDING) -> EXCLUSIVE
** PENDING -> EXCLUSIVE
**
** This routine will only increase a lock. Use the sqlite3OsUnlock()
** routine to lower a locking level.
*/
static int unixLock(sqlite3_file *id, int eFileLock){
/* The following describes the implementation of the various locks and
** lock transitions in terms of the POSIX advisory shared and exclusive
** lock primitives (called read-locks and write-locks below, to avoid
** confusion with SQLite lock names). The algorithms are complicated
** slightly in order to be compatible with Windows95 systems simultaneously
** accessing the same database file, in case that is ever required.
**
** Symbols defined in os.h indentify the 'pending byte' and the 'reserved
** byte', each single bytes at well known offsets, and the 'shared byte
** range', a range of 510 bytes at a well known offset.
**
** To obtain a SHARED lock, a read-lock is obtained on the 'pending
** byte'. If this is successful, 'shared byte range' is read-locked
** and the lock on the 'pending byte' released. (Legacy note: When
** SQLite was first developed, Windows95 systems were still very common,
** and Widnows95 lacks a shared-lock capability. So on Windows95, a
** single randomly selected by from the 'shared byte range' is locked.
** Windows95 is now pretty much extinct, but this work-around for the
** lack of shared-locks on Windows95 lives on, for backwards
** compatibility.)
**
** A process may only obtain a RESERVED lock after it has a SHARED lock.
** A RESERVED lock is implemented by grabbing a write-lock on the
** 'reserved byte'.
**
** A process may only obtain a PENDING lock after it has obtained a
** SHARED lock. A PENDING lock is implemented by obtaining a write-lock
** on the 'pending byte'. This ensures that no new SHARED locks can be
** obtained, but existing SHARED locks are allowed to persist. A process
** does not have to obtain a RESERVED lock on the way to a PENDING lock.
** This property is used by the algorithm for rolling back a journal file
** after a crash.
**
** An EXCLUSIVE lock, obtained after a PENDING lock is held, is
** implemented by obtaining a write-lock on the entire 'shared byte
** range'. Since all other locks require a read-lock on one of the bytes
** within this range, this ensures that no other locks are held on the
** database.
*/
int rc = SQLITE_OK;
unixFile *pFile = (unixFile*)id;
unixInodeInfo *pInode;
struct flock lock;
int tErrno = 0;
assert( pFile );
OSTRACE(("LOCK %d %s was %s(%s,%d) pid=%d (unix)\n", pFile->h,
azFileLock(eFileLock), azFileLock(pFile->eFileLock),
azFileLock(pFile->pInode->eFileLock), pFile->pInode->nShared,
osGetpid(0)));
/* If there is already a lock of this type or more restrictive on the
** unixFile, do nothing. Don't use the end_lock: exit path, as
** unixEnterMutex() hasn't been called yet.
*/
if( pFile->eFileLock>=eFileLock ){
OSTRACE(("LOCK %d %s ok (already held) (unix)\n", pFile->h,
azFileLock(eFileLock)));
return SQLITE_OK;
}
/* Make sure the locking sequence is correct.
** (1) We never move from unlocked to anything higher than shared lock.
** (2) SQLite never explicitly requests a pendig lock.
** (3) A shared lock is always held when a reserve lock is requested.
*/
assert( pFile->eFileLock!=NO_LOCK || eFileLock==SHARED_LOCK );
assert( eFileLock!=PENDING_LOCK );
assert( eFileLock!=RESERVED_LOCK || pFile->eFileLock==SHARED_LOCK );
/* This mutex is needed because pFile->pInode is shared across threads
*/
pInode = pFile->pInode;
sqlite3_mutex_enter(pInode->pLockMutex);
/* If some thread using this PID has a lock via a different unixFile*
** handle that precludes the requested lock, return BUSY.
*/
if( (pFile->eFileLock!=pInode->eFileLock &&
(pInode->eFileLock>=PENDING_LOCK || eFileLock>SHARED_LOCK))
){
rc = SQLITE_BUSY;
goto end_lock;
}
/* If a SHARED lock is requested, and some thread using this PID already
** has a SHARED or RESERVED lock, then increment reference counts and
** return SQLITE_OK.
*/
if( eFileLock==SHARED_LOCK &&
(pInode->eFileLock==SHARED_LOCK || pInode->eFileLock==RESERVED_LOCK) ){
assert( eFileLock==SHARED_LOCK );
assert( pFile->eFileLock==0 );
assert( pInode->nShared>0 );
pFile->eFileLock = SHARED_LOCK;
pInode->nShared++;
pInode->nLock++;
goto end_lock;
}
/* A PENDING lock is needed before acquiring a SHARED lock and before
** acquiring an EXCLUSIVE lock. For the SHARED lock, the PENDING will
** be released.
*/
lock.l_len = 1L;
lock.l_whence = SEEK_SET;
if( eFileLock==SHARED_LOCK
|| (eFileLock==EXCLUSIVE_LOCK && pFile->eFileLock<PENDING_LOCK)
){
lock.l_type = (eFileLock==SHARED_LOCK?F_RDLCK:F_WRLCK);
lock.l_start = PENDING_BYTE;
if( unixFileLock(pFile, &lock) ){
tErrno = errno;
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
if( rc!=SQLITE_BUSY ){
storeLastErrno(pFile, tErrno);
}
goto end_lock;
}
}
storeLastErrno(pFile, tErrno);
}
}
}
#ifdef SQLITE_DEBUG
/* Set up the transaction-counter change checking flags when
** transitioning from a SHARED to a RESERVED lock. The change
** from SHARED to RESERVED marks the beginning of a normal
** write operation (not a hot journal rollback).
*/
if( rc==SQLITE_OK
&& pFile->eFileLock<=SHARED_LOCK
&& eFileLock==RESERVED_LOCK
){
pFile->transCntrChng = 0;
pFile->dbUpdate = 0;
pFile->inNormalWrite = 1;
}
#endif
if( rc==SQLITE_OK ){
pFile->eFileLock = eFileLock;
pInode->eFileLock = eFileLock;
}else if( eFileLock==EXCLUSIVE_LOCK ){
pFile->eFileLock = PENDING_LOCK;
pInode->eFileLock = PENDING_LOCK;
}
end_lock:
sqlite3_mutex_leave(pInode->pLockMutex);
OSTRACE(("LOCK %d %s %s (unix)\n", pFile->h, azFileLock(eFileLock),
rc==SQLITE_OK ? "ok" : "failed"));
return rc;
}
/*
** Add the file descriptor used by file handle pFile to the corresponding
** pUnused list.
*/
static void setPendingFd(unixFile *pFile){
unixInodeInfo *pInode = pFile->pInode;
UnixUnusedFd *p = pFile->pPreallocatedUnused;
assert( unixFileMutexHeld(pFile) );
p->pNext = pInode->pUnused;
pInode->pUnused = p;
pFile->h = -1;
pFile->pPreallocatedUnused = 0;
}
/*
** Lower the locking level on file descriptor pFile to eFileLock. eFileLock
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
**
** If handleNFSUnlock is true, then on downgrading an EXCLUSIVE_LOCK to SHARED
** the byte range is divided into 2 parts and the first part is unlocked then
** set to a read lock, then the other part is simply unlocked. This works
** around a bug in BSD NFS lockd (also seen on MacOSX 10.3+) that fails to
** remove the write lock on a region when a read lock is set.
*/
static int posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
unixFile *pFile = (unixFile*)id;
unixInodeInfo *pInode;
struct flock lock;
int rc = SQLITE_OK;
assert( pFile );
OSTRACE(("UNLOCK %d %d was %d(%d,%d) pid=%d (unix)\n", pFile->h, eFileLock,
pFile->eFileLock, pFile->pInode->eFileLock, pFile->pInode->nShared,
osGetpid(0)));
assert( eFileLock<=SHARED_LOCK );
if( pFile->eFileLock<=eFileLock ){
return SQLITE_OK;
}
pInode = pFile->pInode;
sqlite3_mutex_enter(pInode->pLockMutex);
assert( pInode->nShared!=0 );
if( pFile->eFileLock>SHARED_LOCK ){
assert( pInode->eFileLock==pFile->eFileLock );
#ifdef SQLITE_DEBUG
/* When reducing a lock such that other processes can start
** reading the database file again, make sure that the
** transaction counter was updated if any part of the database
** file changed. If the transaction counter is not updated,
** other connections to the same file might not realize that
** the file has changed and hence might not know to flush their
** cache. The use of a stale cache can lead to database corruption.
*/
pFile->inNormalWrite = 0;
#endif
/* downgrading to a shared lock on NFS involves clearing the write lock
** before establishing the readlock - to avoid a race condition we downgrade
** the lock in 2 blocks, so that part of the range will be covered by a
** write lock until the rest is covered by a read lock:
** 1: [WWWWW]
** 2: [....W]
** 3: [RRRRW]
** 4: [RRRR.]
*/
if( eFileLock==SHARED_LOCK ){
#if !defined(__APPLE__) || !SQLITE_ENABLE_LOCKING_STYLE
(void)handleNFSUnlock;
assert( handleNFSUnlock==0 );
#endif
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
if( handleNFSUnlock ){
int tErrno; /* Error code from system call errors */
off_t divSize = SHARED_SIZE - 1;
lock.l_type = F_UNLCK;
lock.l_whence = SEEK_SET;
lock.l_start = SHARED_FIRST;
lock.l_len = divSize;
if( unixFileLock(pFile, &lock)==(-1) ){
static int nolockCheckReservedLock(sqlite3_file *NotUsed, int *pResOut){
UNUSED_PARAMETER(NotUsed);
*pResOut = 0;
return SQLITE_OK;
}
static int nolockLock(sqlite3_file *NotUsed, int NotUsed2){
UNUSED_PARAMETER2(NotUsed, NotUsed2);
return SQLITE_OK;
}
static int nolockUnlock(sqlite3_file *NotUsed, int NotUsed2){
UNUSED_PARAMETER2(NotUsed, NotUsed2);
return SQLITE_OK;
}
/*
** Close the file.
*/
static int nolockClose(sqlite3_file *id) {
return closeUnixFile(id);
}
/******************* End of the no-op lock implementation *********************
******************************************************************************/
/******************************************************************************
************************* Begin dot-file Locking ******************************
**
** The dotfile locking implementation uses the existence of separate lock
** files (really a directory) to control access to the database. This works
** on just about every filesystem imaginable. But there are serious downsides:
**
** (1) There is zero concurrency. A single reader blocks all other
** connections from reading or writing the database.
**
** (2) An application crash or power loss can leave stale lock files
** sitting around that need to be cleared manually.
**
** Nevertheless, a dotlock is an appropriate locking mode for use if no
** other locking strategy is available.
**
** Dotfile locking works by creating a subdirectory in the same directory as
** the database and with the same name but with a ".lock" extension added.
** The existence of a lock directory implies an EXCLUSIVE lock. All other
** lock types (SHARED, RESERVED, PENDING) are mapped into EXCLUSIVE.
*/
/*
** The file suffix added to the data base filename in order to create the
** lock directory.
*/
#define DOTLOCK_SUFFIX ".lock"
/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero. The return value
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
**
** In dotfile locking, either a lock exists or it does not. So in this
** variation of CheckReservedLock(), *pResOut is set to true if any lock
** is held on the file and false if the file is unlocked.
*/
static int dotlockCheckReservedLock(sqlite3_file *id, int *pResOut) {
int rc = SQLITE_OK;
int reserved = 0;
unixFile *pFile = (unixFile*)id;
SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
assert( pFile );
reserved = osAccess((const char*)pFile->lockingContext, 0)==0;
OSTRACE(("TEST WR-LOCK %d %d %d (dotlock)\n", pFile->h, rc, reserved));
*pResOut = reserved;
return rc;
}
/*
** Lock the file with the lock specified by parameter eFileLock - one
** of the following:
**
** (1) SHARED_LOCK
** (2) RESERVED_LOCK
** (3) PENDING_LOCK
** (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between. The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal. The following chart shows the allowed
** transitions and the inserted intermediate states:
**
** UNLOCKED -> SHARED
** SHARED -> RESERVED
** SHARED -> (PENDING) -> EXCLUSIVE
** RESERVED -> (PENDING) -> EXCLUSIVE
** PENDING -> EXCLUSIVE
**
** This routine will only increase a lock. Use the sqlite3OsUnlock()
** routine to lower a locking level.
**
** With dotfile locking, we really only support state (4): EXCLUSIVE.
** But we track the other locking levels internally.
*/
static int dotlockLock(sqlite3_file *id, int eFileLock) {
unixFile *pFile = (unixFile*)id;
char *zLockFile = (char *)pFile->lockingContext;
int rc = SQLITE_OK;
/* If we have any lock, then the lock file already exists. All we have
** to do is adjust our internal record of the lock level.
*/
if( pFile->eFileLock > NO_LOCK ){
pFile->eFileLock = eFileLock;
/* Always update the timestamp on the old file */
#ifdef HAVE_UTIME
utime(zLockFile, NULL);
#else
utimes(zLockFile, NULL);
#endif
return SQLITE_OK;
if( EAGAIN != tErrno ){
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK);
storeLastErrno(pFile, tErrno);
} else {
/* someone else has the lock when we are in NO_LOCK */
reserved = (pFile->eFileLock < SHARED_LOCK);
}
}else{
/* we could have it if we want it */
sem_post(pSem);
}
}
OSTRACE(("TEST WR-LOCK %d %d %d (sem)\n", pFile->h, rc, reserved));
*pResOut = reserved;
return rc;
}
/*
** Lock the file with the lock specified by parameter eFileLock - one
** of the following:
**
** (1) SHARED_LOCK
** (2) RESERVED_LOCK
** (3) PENDING_LOCK
** (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between. The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal. The following chart shows the allowed
** transitions and the inserted intermediate states:
**
** UNLOCKED -> SHARED
** SHARED -> RESERVED
** SHARED -> (PENDING) -> EXCLUSIVE
** RESERVED -> (PENDING) -> EXCLUSIVE
** PENDING -> EXCLUSIVE
**
** Semaphore locks only really support EXCLUSIVE locks. We track intermediate
** lock states in the sqlite3_file structure, but all locks SHARED or
** above are really EXCLUSIVE locks and exclude all other processes from
** access the file.
**
** This routine will only increase a lock. Use the sqlite3OsUnlock()
** routine to lower a locking level.
*/
static int semXLock(sqlite3_file *id, int eFileLock) {
unixFile *pFile = (unixFile*)id;
sem_t *pSem = pFile->pInode->pSem;
int rc = SQLITE_OK;
/* if we already have a lock, it is exclusive.
** Just adjust level and punt on outta here. */
if (pFile->eFileLock > NO_LOCK) {
pFile->eFileLock = eFileLock;
rc = SQLITE_OK;
goto sem_end_lock;
}
/* lock semaphore now but bail out when already locked. */
if( sem_trywait(pSem)==-1 ){
rc = SQLITE_BUSY;
goto sem_end_lock;
}
/* got it, set the type and return ok */
pFile->eFileLock = eFileLock;
sem_end_lock:
return rc;
}
/*
** Lower the locking level on file descriptor pFile to eFileLock. eFileLock
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int semXUnlock(sqlite3_file *id, int eFileLock) {
unixFile *pFile = (unixFile*)id;
sem_t *pSem = pFile->pInode->pSem;
assert( pFile );
assert( pSem );
OSTRACE(("UNLOCK %d %d was %d pid=%d (sem)\n", pFile->h, eFileLock,
pFile->eFileLock, osGetpid(0)));
assert( eFileLock<=SHARED_LOCK );
/* no-op if possible */
if( pFile->eFileLock==eFileLock ){
return SQLITE_OK;
}
/* shared can just be set because we always have an exclusive */
if (eFileLock==SHARED_LOCK) {
pFile->eFileLock = eFileLock;
return SQLITE_OK;
}
/* no, really unlock. */
if ( sem_post(pSem)==-1 ) {
int rc, tErrno = errno;
rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
if( IS_LOCK_ERROR(rc) ){
storeLastErrno(pFile, tErrno);
}
return rc;
}
pFile->eFileLock = NO_LOCK;
return SQLITE_OK;
}
/*
** Close a file.
*/
static int semXClose(sqlite3_file *id) {
if( id ){
unixFile *pFile = (unixFile*)id;
semXUnlock(id, NO_LOCK);
assert( pFile );
assert( unixFileMutexNotheld(pFile) );
unixEnterMutex();
releaseInodeInfo(pFile);
unixLeaveMutex();
closeUnixFile(id);
}
return SQLITE_OK;
}
#endif /* OS_VXWORKS */
/*
** Named semaphore locking is only available on VxWorks.
**
*************** End of the named semaphore lock implementation ****************
******************************************************************************/
/******************************************************************************
*************************** Begin AFP Locking *********************************
**
** AFP is the Apple Filing Protocol. AFP is a network filesystem found
** on Apple Macintosh computers - both OS9 and OSX.
**
** Third-party implementations of AFP are available. But this code here
** only works on OSX.
*/
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
/*
** The afpLockingContext structure contains all afp lock specific state
*/
typedef struct afpLockingContext afpLockingContext;
struct afpLockingContext {
int reserved;
const char *dbPath; /* Name of the open file */
};
struct ByteRangeLockPB2
{
unsigned long long offset; /* offset to first byte to lock */
unsigned long long length; /* nbr of bytes to lock */
unsigned long long retRangeStart; /* nbr of 1st byte locked if successful */
unsigned char unLockFlag; /* 1 = unlock, 0 = lock */
unsigned char startEndFlag; /* 1=rel to end of fork, 0=rel to start */
int fd; /* file desc to assoc this lock with */
};
#define afpfsByteRangeLock2FSCTL _IOWR('z', 23, struct ByteRangeLockPB2)
/*
** This is a utility for setting or clearing a bit-range lock on an
** AFP filesystem.
**
** Return SQLITE_OK on success, SQLITE_BUSY on failure.
*/
static int afpSetLock(
const char *path, /* Name of the file to be locked or unlocked */
unixFile *pFile, /* Open file descriptor on path */
unsigned long long offset, /* First byte to be locked */
unsigned long long length, /* Number of bytes to lock */
int setLockFlag /* True to set lock. False to clear lock */
){
struct ByteRangeLockPB2 pb;
int err;
pb.unLockFlag = setLockFlag ? 0 : 1;
pb.startEndFlag = 0;
pb.offset = offset;
pb.length = length;
pb.fd = pFile->h;
OSTRACE(("AFPSETLOCK [%s] for %d%s in range %llx:%llx\n",
(setLockFlag?"ON":"OFF"), pFile->h, (pb.fd==-1?"[testval-1]":""),
offset, length));
err = fsctl(path, afpfsByteRangeLock2FSCTL, &pb, 0);
if ( err==-1 ) {
int rc;
int tErrno = errno;
OSTRACE(("AFPSETLOCK failed to fsctl() '%s' %d %s\n",
path, tErrno, strerror(tErrno)));
#ifdef SQLITE_IGNORE_AFP_LOCK_ERRORS
rc = SQLITE_BUSY;
#else
rc = sqliteErrorFromPosixError(tErrno,
setLockFlag ? SQLITE_IOERR_LOCK : SQLITE_IOERR_UNLOCK);
#endif /* SQLITE_IGNORE_AFP_LOCK_ERRORS */
if( IS_LOCK_ERROR(rc) ){
storeLastErrno(pFile, tErrno);
}
return rc;
} else {
return SQLITE_OK;
}
}
/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero. The return value
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
*/
static int afpCheckReservedLock(sqlite3_file *id, int *pResOut){
int rc = SQLITE_OK;
int reserved = 0;
unixFile *pFile = (unixFile*)id;
afpLockingContext *context;
SimulateIOError( return SQLITE_IOERR_CHECKRESERVEDLOCK; );
assert( pFile );
context = (afpLockingContext *) pFile->lockingContext;
if( context->reserved ){
*pResOut = 1;
return SQLITE_OK;
}
sqlite3_mutex_enter(pFile->pInode->pLockMutex);
/* Check if a thread in this process holds such a lock */
if( pFile->pInode->eFileLock>SHARED_LOCK ){
reserved = 1;
reserved = 1;
}
if( IS_LOCK_ERROR(lrc) ){
rc=lrc;
}
}
sqlite3_mutex_leave(pFile->pInode->pLockMutex);
OSTRACE(("TEST WR-LOCK %d %d %d (afp)\n", pFile->h, rc, reserved));
*pResOut = reserved;
return rc;
}
/*
** Lock the file with the lock specified by parameter eFileLock - one
** of the following:
**
** (1) SHARED_LOCK
** (2) RESERVED_LOCK
** (3) PENDING_LOCK
** (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between. The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal. The following chart shows the allowed
** transitions and the inserted intermediate states:
**
** UNLOCKED -> SHARED
** SHARED -> RESERVED
** SHARED -> (PENDING) -> EXCLUSIVE
** RESERVED -> (PENDING) -> EXCLUSIVE
** PENDING -> EXCLUSIVE
**
** This routine will only increase a lock. Use the sqlite3OsUnlock()
** routine to lower a locking level.
*/
static int afpLock(sqlite3_file *id, int eFileLock){
int rc = SQLITE_OK;
unixFile *pFile = (unixFile*)id;
unixInodeInfo *pInode = pFile->pInode;
afpLockingContext *context = (afpLockingContext *) pFile->lockingContext;
assert( pFile );
OSTRACE(("LOCK %d %s was %s(%s,%d) pid=%d (afp)\n", pFile->h,
azFileLock(eFileLock), azFileLock(pFile->eFileLock),
azFileLock(pInode->eFileLock), pInode->nShared , osGetpid(0)));
/* If there is already a lock of this type or more restrictive on the
** unixFile, do nothing. Don't use the afp_end_lock: exit path, as
** unixEnterMutex() hasn't been called yet.
*/
if( pFile->eFileLock>=eFileLock ){
OSTRACE(("LOCK %d %s ok (already held) (afp)\n", pFile->h,
azFileLock(eFileLock)));
return SQLITE_OK;
}
/* Make sure the locking sequence is correct
** (1) We never move from unlocked to anything higher than shared lock.
** (2) SQLite never explicitly requests a pendig lock.
** (3) A shared lock is always held when a reserve lock is requested.
*/
assert( pFile->eFileLock!=NO_LOCK || eFileLock==SHARED_LOCK );
assert( eFileLock!=PENDING_LOCK );
assert( eFileLock!=RESERVED_LOCK || pFile->eFileLock==SHARED_LOCK );
/* This mutex is needed because pFile->pInode is shared across threads
*/
pInode = pFile->pInode;
sqlite3_mutex_enter(pInode->pLockMutex);
/* If some thread using this PID has a lock via a different unixFile*
** handle that precludes the requested lock, return BUSY.
*/
if( (pFile->eFileLock!=pInode->eFileLock &&
(pInode->eFileLock>=PENDING_LOCK || eFileLock>SHARED_LOCK))
){
rc = SQLITE_BUSY;
goto afp_end_lock;
}
/* If a SHARED lock is requested, and some thread using this PID already
** has a SHARED or RESERVED lock, then increment reference counts and
** return SQLITE_OK.
*/
if( eFileLock==SHARED_LOCK &&
(pInode->eFileLock==SHARED_LOCK || pInode->eFileLock==RESERVED_LOCK) ){
assert( eFileLock==SHARED_LOCK );
assert( pFile->eFileLock==0 );
assert( pInode->nShared>0 );
pFile->eFileLock = SHARED_LOCK;
pInode->nShared++;
pInode->nLock++;
goto afp_end_lock;
}
/* A PENDING lock is needed before acquiring a SHARED lock and before
** acquiring an EXCLUSIVE lock. For the SHARED lock, the PENDING will
** be released.
*/
if( eFileLock==SHARED_LOCK
|| (eFileLock==EXCLUSIVE_LOCK && pFile->eFileLock<PENDING_LOCK)
){
int failed;
failed = afpSetLock(context->dbPath, pFile, PENDING_BYTE, 1, 1);
if (failed) {
rc = failed;
goto afp_end_lock;
}
}
/* If control gets to this point, then actually go ahead and make
** operating system calls for the specified lock.
*/
if( eFileLock==SHARED_LOCK ){
int lrc1, lrc2, lrc1Errno = 0;
long lk, mask;
assert( pInode->nShared==0 );
#if !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0
/*
** Return the system page size.
**
** This function should not be called directly by other code in this file.
** Instead, it should be called via macro osGetpagesize().
*/
static int unixGetpagesize(void){
#if OS_VXWORKS
return 1024;
#elif defined(_BSD_SOURCE)
return getpagesize();
#else
return (int)sysconf(_SC_PAGESIZE);
#endif
}
#endif /* !defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0 */
#ifndef SQLITE_OMIT_WAL
/*
** Object used to represent an shared memory buffer.
**
** When multiple threads all reference the same wal-index, each thread
** has its own unixShm object, but they all point to a single instance
** of this unixShmNode object. In other words, each wal-index is opened
** only once per process.
**
** Each unixShmNode object is connected to a single unixInodeInfo object.
** We could coalesce this object into unixInodeInfo, but that would mean
** every open file that does not use shared memory (in other words, most
** open files) would have to carry around this extra information. So
** the unixInodeInfo object contains a pointer to this unixShmNode object
** and the unixShmNode object is created only when needed.
**
** unixMutexHeld() must be true when creating or destroying
** this object or while reading or writing the following fields:
**
** nRef
**
** The following fields are read-only after the object is created:
**
** hShm
** zFilename
**
** Either unixShmNode.pShmMutex must be held or unixShmNode.nRef==0 and
** unixMutexHeld() is true when reading or writing any other field
** in this structure.
*/
struct unixShmNode {
unixInodeInfo *pInode; /* unixInodeInfo that owns this SHM node */
sqlite3_mutex *pShmMutex; /* Mutex to access this object */
char *zFilename; /* Name of the mmapped file */
int hShm; /* Open file descriptor */
int szRegion; /* Size of shared-memory regions */
u16 nRegion; /* Size of array apRegion */
u8 isReadonly; /* True if read-only */
u8 isUnlocked; /* True if no DMS lock held */
char **apRegion; /* Array of mapped shared-memory regions */
int nRef; /* Number of unixShm objects pointing to this */
unixShm *pFirst; /* All unixShm objects pointing to this */
#ifdef SQLITE_DEBUG
u8 exclMask; /* Mask of exclusive locks held */
u8 sharedMask; /* Mask of shared locks held */
u8 nextShmId; /* Next available unixShm.id value */
#endif
};
/*
** Structure used internally by this VFS to record the state of an
** open shared memory connection.
**
** The following fields are initialized when this object is created and
** are read-only thereafter:
**
** unixShm.pShmNode
** unixShm.id
**
** All other fields are read/write. The unixShm.pShmNode->pShmMutex must
** be held while accessing any read/write fields.
*/
struct unixShm {
unixShmNode *pShmNode; /* The underlying unixShmNode object */
unixShm *pNext; /* Next unixShm with the same unixShmNode */
u8 hasMutex; /* True if holding the unixShmNode->pShmMutex */
u8 id; /* Id of this connection within its unixShmNode */
u16 sharedMask; /* Mask of shared locks held */
u16 exclMask; /* Mask of exclusive locks held */
};
/*
** Constants used for locking
*/
#define UNIX_SHM_BASE ((22+SQLITE_SHM_NLOCK)*4) /* first lock byte */
#define UNIX_SHM_DMS (UNIX_SHM_BASE+SQLITE_SHM_NLOCK) /* deadman switch */
/*
** Apply posix advisory locks for all bytes from ofst through ofst+n-1.
**
** Locks block if the mask is exactly UNIX_SHM_C and are non-blocking
** otherwise.
*/
static int unixShmSystemLock(
unixFile *pFile, /* Open connection to the WAL file */
int lockType, /* F_UNLCK, F_RDLCK, or F_WRLCK */
int ofst, /* First byte of the locking range */
int n /* Number of bytes to lock */
){
unixShmNode *pShmNode; /* Apply locks to this open shared-memory segment */
struct flock f; /* The posix advisory locking structure */
int rc = SQLITE_OK; /* Result code form fcntl() */
/* Access to the unixShmNode object is serialized by the caller */
pShmNode = pFile->pInode->pShmNode;
assert( pShmNode->nRef==0 || sqlite3_mutex_held(pShmNode->pShmMutex) );
assert( pShmNode->nRef>0 || unixMutexHeld() );
/* Shared locks never span more than one byte */
pShmNode->sharedMask, pShmNode->exclMask));
}
#endif
return rc;
}
/*
** Return the minimum number of 32KB shm regions that should be mapped at
** a time, assuming that each mapping must be an integer multiple of the
** current system page-size.
**
** Usually, this is 1. The exception seems to be systems that are configured
** to use 64KB pages - in this case each mapping must cover at least two
** shm regions.
*/
static int unixShmRegionPerMap(void){
int shmsz = 32*1024; /* SHM region size */
int pgsz = osGetpagesize(); /* System page size */
assert( ((pgsz-1)&pgsz)==0 ); /* Page size must be a power of 2 */
if( pgsz<shmsz ) return 1;
return pgsz/shmsz;
}
/*
** Purge the unixShmNodeList list of all entries with unixShmNode.nRef==0.
**
** This is not a VFS shared-memory method; it is a utility function called
** by VFS shared-memory methods.
*/
static void unixShmPurge(unixFile *pFd){
unixShmNode *p = pFd->pInode->pShmNode;
assert( unixMutexHeld() );
if( p && ALWAYS(p->nRef==0) ){
int nShmPerMap = unixShmRegionPerMap();
int i;
assert( p->pInode==pFd->pInode );
sqlite3_mutex_free(p->pShmMutex);
for(i=0; i<p->nRegion; i+=nShmPerMap){
if( p->hShm>=0 ){
osMunmap(p->apRegion[i], p->szRegion);
}else{
sqlite3_free(p->apRegion[i]);
}
}
sqlite3_free(p->apRegion);
if( p->hShm>=0 ){
robust_close(pFd, p->hShm, __LINE__);
p->hShm = -1;
}
p->pInode->pShmNode = 0;
sqlite3_free(p);
}
}
/*
** The DMS lock has not yet been taken on shm file pShmNode. Attempt to
** take it now. Return SQLITE_OK if successful, or an SQLite error
** code otherwise.
**
** If the DMS cannot be locked because this is a readonly_shm=1
** connection and no other process already holds a lock, return
** SQLITE_READONLY_CANTINIT and set pShmNode->isUnlocked=1.
*/
static int unixLockSharedMemory(unixFile *pDbFd, unixShmNode *pShmNode){
struct flock lock;
int rc = SQLITE_OK;
/* Use F_GETLK to determine the locks other processes are holding
** on the DMS byte. If it indicates that another process is holding
** a SHARED lock, then this process may also take a SHARED lock
** and proceed with opening the *-shm file.
**
** Or, if no other process is holding any lock, then this process
** is the first to open it. In this case take an EXCLUSIVE lock on the
** DMS byte and truncate the *-shm file to zero bytes in size. Then
** downgrade to a SHARED lock on the DMS byte.
**
** If another process is holding an EXCLUSIVE lock on the DMS byte,
** return SQLITE_BUSY to the caller (it will try again). An earlier
** version of this code attempted the SHARED lock at this point. But
** this introduced a subtle race condition: if the process holding
** EXCLUSIVE failed just before truncating the *-shm file, then this
** process might open and use the *-shm file without truncating it.
** And if the *-shm file has been corrupted by a power failure or
** system crash, the database itself may also become corrupt. */
lock.l_whence = SEEK_SET;
lock.l_start = UNIX_SHM_DMS;
lock.l_len = 1;
lock.l_type = F_WRLCK;
if( osFcntl(pShmNode->hShm, F_GETLK, &lock)!=0 ) {
rc = SQLITE_IOERR_LOCK;
}else if( lock.l_type==F_UNLCK ){
if( pShmNode->isReadonly ){
pShmNode->isUnlocked = 1;
rc = SQLITE_READONLY_CANTINIT;
}else{
rc = unixShmSystemLock(pDbFd, F_WRLCK, UNIX_SHM_DMS, 1);
/* The first connection to attach must truncate the -shm file. We
** truncate to 3 bytes (an arbitrary small number, less than the
** -shm header size) rather than 0 as a system debugging aid, to
** help detect if a -shm file truncation is legitimate or is the work
** or a rogue process. */
if( rc==SQLITE_OK && robust_ftruncate(pShmNode->hShm, 3) ){
rc = unixLogError(SQLITE_IOERR_SHMOPEN,"ftruncate",pShmNode->zFilename);
}
}
}else if( lock.l_type==F_WRLCK ){
rc = SQLITE_BUSY;
}
if( rc==SQLITE_OK ){
assert( lock.l_type==F_UNLCK || lock.l_type==F_RDLCK );
rc = unixShmSystemLock(pDbFd, F_RDLCK, UNIX_SHM_DMS, 1);
}
return rc;
}
/*
** Open a shared-memory area associated with open database file pDbFd.
** This particular implementation uses mmapped files.
**
** The file used to implement shared-memory is in the same directory
** as the open database file and has the same name as the open database
** file with the "-shm" suffix added. For example, if the database file
** is "/home/user1/config.db" then the file that is created and mmapped
** for shared memory will be called "/home/user1/config.db-shm".
**
** Another approach to is to use files in /dev/shm or /dev/tmp or an
** some other tmpfs mount. But if a file in a different directory
** from the database file is used, then differing access permissions
** or a chroot() might cause two different processes on the same
** database to end up using different files for shared memory -
** meaning that their memory would not really be shared - resulting
** in database corruption. Nevertheless, this tmpfs file usage
** can be enabled at compile-time using -DSQLITE_SHM_DIRECTORY="/dev/shm"
** or the equivalent. The use of the SQLITE_SHM_DIRECTORY compile-time
** option results in an incompatible build of SQLite; builds of SQLite
** that with differing SQLITE_SHM_DIRECTORY settings attempt to use the
** same database file at the same time, database corruption will likely
** result. The SQLITE_SHM_DIRECTORY compile-time option is considered
** "unsupported" and may go away in a future SQLite release.
**
** When opening a new shared-memory file, if no other instances of that
** file are currently open, in this process or in other processes, then
** the file must be truncated to zero length or have its header cleared.
**
** If the original database file (pDbFd) is using the "unix-excl" VFS
** that means that an exclusive lock is held on the database file and
** that no other processes are able to read or write the database. In
** that case, we do not really need shared memory. No shared memory
** file is created. The shared memory will be simulated with heap memory.
*/
static int unixOpenSharedMemory(unixFile *pDbFd){
struct unixShm *p = 0; /* The connection to be opened */
** left to do is to link the new object into the linked list starting
** at pShmNode->pFirst. This must be done while holding the
** pShmNode->pShmMutex.
*/
sqlite3_mutex_enter(pShmNode->pShmMutex);
p->pNext = pShmNode->pFirst;
pShmNode->pFirst = p;
sqlite3_mutex_leave(pShmNode->pShmMutex);
return rc;
/* Jump here on any error */
shm_open_err:
unixShmPurge(pDbFd); /* This call frees pShmNode if required */
sqlite3_free(p);
unixLeaveMutex();
return rc;
}
/*
** This function is called to obtain a pointer to region iRegion of the
** shared-memory associated with the database file fd. Shared-memory regions
** are numbered starting from zero. Each shared-memory region is szRegion
** bytes in size.
**
** If an error occurs, an error code is returned and *pp is set to NULL.
**
** Otherwise, if the bExtend parameter is 0 and the requested shared-memory
** region has not been allocated (by any client, including one running in a
** separate process), then *pp is set to NULL and SQLITE_OK returned. If
** bExtend is non-zero and the requested shared-memory region has not yet
** been allocated, it is allocated by this function.
**
** If the shared-memory region has already been allocated or is allocated by
** this call as described above, then it is mapped into this processes
** address space (if it is not already), *pp is set to point to the mapped
** memory and SQLITE_OK returned.
*/
static int unixShmMap(
sqlite3_file *fd, /* Handle open on database file */
int iRegion, /* Region to retrieve */
int szRegion, /* Size of regions */
int bExtend, /* True to extend file if necessary */
void volatile **pp /* OUT: Mapped memory */
){
unixFile *pDbFd = (unixFile*)fd;
unixShm *p;
unixShmNode *pShmNode;
int rc = SQLITE_OK;
int nShmPerMap = unixShmRegionPerMap();
int nReqRegion;
/* If the shared-memory file has not yet been opened, open it now. */
if( pDbFd->pShm==0 ){
rc = unixOpenSharedMemory(pDbFd);
if( rc!=SQLITE_OK ) return rc;
}
p = pDbFd->pShm;
pShmNode = p->pShmNode;
sqlite3_mutex_enter(pShmNode->pShmMutex);
if( pShmNode->isUnlocked ){
rc = unixLockSharedMemory(pDbFd, pShmNode);
if( rc!=SQLITE_OK ) goto shmpage_out;
pShmNode->isUnlocked = 0;
}
assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 );
assert( pShmNode->pInode==pDbFd->pInode );
assert( pShmNode->hShm>=0 || pDbFd->pInode->bProcessLock==1 );
assert( pShmNode->hShm<0 || pDbFd->pInode->bProcessLock==0 );
/* Minimum number of regions required to be mapped. */
nReqRegion = ((iRegion+nShmPerMap) / nShmPerMap) * nShmPerMap;
if( pShmNode->nRegion<nReqRegion ){
char **apNew; /* New apRegion[] array */
int nByte = nReqRegion*szRegion; /* Minimum required file size */
struct stat sStat; /* Used by fstat() */
pShmNode->szRegion = szRegion;
if( pShmNode->hShm>=0 ){
/* The requested region is not mapped into this processes address space.
** Check to see if it has been allocated (i.e. if the wal-index file is
** large enough to contain the requested region).
*/
if( osFstat(pShmNode->hShm, &sStat) ){
rc = SQLITE_IOERR_SHMSIZE;
goto shmpage_out;
}
if( sStat.st_size<nByte ){
/* The requested memory region does not exist. If bExtend is set to
** false, exit early. *pp will be set to NULL and SQLITE_OK returned.
*/
if( !bExtend ){
goto shmpage_out;
}
/* Alternatively, if bExtend is true, extend the file. Do this by
** writing a single byte to the end of each (OS) page being
** allocated or extended. Technically, we need only write to the
** last page in order to extend the file. But writing to all new
** pages forces the OS to allocate them immediately, which reduces
** the chances of SIGBUS while accessing the mapped region later on.
*/
else{
static const int pgsz = 4096;
int iPg;
/* Write to the last byte of each newly allocated or extended page */
assert( (nByte % pgsz)==0 );
for(iPg=(sStat.st_size/pgsz); iPg<(nByte/pgsz); iPg++){
int x = 0;
if( seekAndWriteFd(pShmNode->hShm, iPg*pgsz + pgsz-1,"",1,&x)!=1 ){
const char *zFile = pShmNode->zFilename;
rc = unixLogError(SQLITE_IOERR_SHMSIZE, "write", zFile);
goto shmpage_out;
}
}
}
}
}
/* Map the requested memory region into this processes address space. */
apNew = (char **)sqlite3_realloc(
pShmNode->apRegion, nReqRegion*sizeof(char *)
);
if( !apNew ){
rc = SQLITE_IOERR_NOMEM_BKPT;
goto shmpage_out;
}
pShmNode->apRegion = apNew;
while( pShmNode->nRegion<nReqRegion ){
int nMap = szRegion*nShmPerMap;
int i;
void *pMem;
if( pShmNode->hShm>=0 ){
pMem = osMmap(0, nMap,
pShmNode->isReadonly ? PROT_READ : PROT_READ|PROT_WRITE,
MAP_SHARED, pShmNode->hShm, szRegion*(i64)pShmNode->nRegion
);
if( pMem==MAP_FAILED ){
rc = unixLogError(SQLITE_IOERR_SHMMAP, "mmap", pShmNode->zFilename);
goto shmpage_out;
}
}else{
pMem = sqlite3_malloc64(nMap);
if( pMem==0 ){
rc = SQLITE_NOMEM_BKPT;
goto shmpage_out;
}
memset(pMem, 0, nMap);
}
for(i=0; i<nShmPerMap; i++){
pShmNode->apRegion[pShmNode->nRegion+i] = &((char*)pMem)[szRegion*i];
}
pShmNode->nRegion += nShmPerMap;
}
}
shmpage_out:
if( pShmNode->nRegion>iRegion ){
*pp = pShmNode->apRegion[iRegion];
}else{
*pp = 0;
}
if( pShmNode->isReadonly && rc==SQLITE_OK ) rc = SQLITE_READONLY;
sqlite3_mutex_leave(pShmNode->pShmMutex);
return rc;
}
/*
** Change the lock state for a shared-memory segment.
**
** Note that the relationship between SHAREd and EXCLUSIVE locks is a little
** different here than in posix. In xShmLock(), one can go from unlocked
** to shared and back or from unlocked to exclusive and back. But one may
** not go from shared to exclusive or from exclusive to shared.
*/
static int unixShmLock(
sqlite3_file *fd, /* Database file holding the shared memory */
int ofst, /* First lock to acquire or release */
int n, /* Number of locks to acquire or release */
int flags /* What to do with the lock */
){
unixFile *pDbFd = (unixFile*)fd; /* Connection holding shared memory */
unixShm *p = pDbFd->pShm; /* The shared memory being locked */
unixShm *pX; /* For looping over all siblings */
unixShmNode *pShmNode = p->pShmNode; /* The underlying file iNode */
int rc = SQLITE_OK; /* Result code */
u16 mask; /* Mask of locks to take or release */
assert( pShmNode==pDbFd->pInode->pShmNode );
assert( pShmNode->pInode==pDbFd->pInode );
assert( ofst>=0 && ofst+n<=SQLITE_SHM_NLOCK );
assert( n>=1 );
assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED)
|| flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE)
|| flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED)
|| flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );
assert( pShmNode->hShm>=0 || pDbFd->pInode->bProcessLock==1 );
assert( pShmNode->hShm<0 || pDbFd->pInode->bProcessLock==0 );
mask = (1<<(ofst+n)) - (1<<ofst);
assert( n>1 || mask==(1<<ofst) );
sqlite3_mutex_enter(pShmNode->pShmMutex);
if( flags & SQLITE_SHM_UNLOCK ){
u16 allMask = 0; /* Mask of locks held by siblings */
/* See if any siblings hold this same lock */
for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
if( pX==p ) continue;
assert( (pX->exclMask & (p->exclMask|p->sharedMask))==0 );
allMask |= pX->sharedMask;
}
/* Unlock the system-level locks */
if( (mask & allMask)==0 ){
rc = unixShmSystemLock(pDbFd, F_UNLCK, ofst+UNIX_SHM_BASE, n);
}else{
rc = SQLITE_OK;
}
/* Undo the local locks */
if( rc==SQLITE_OK ){
p->exclMask &= ~mask;
p->sharedMask &= ~mask;
}
}else if( flags & SQLITE_SHM_SHARED ){
u16 allShared = 0; /* Union of locks held by connections other than "p" */
/* Find out which shared locks are already held by sibling connections.
** If any sibling already holds an exclusive lock, go ahead and return
** SQLITE_BUSY.
*/
for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
if( (pX->exclMask & mask)!=0 ){
rc = SQLITE_BUSY;
break;
}
allShared |= pX->sharedMask;
}
/* Get shared locks at the system level, if necessary */
if( rc==SQLITE_OK ){
if( (allShared & mask)==0 ){
rc = unixShmSystemLock(pDbFd, F_RDLCK, ofst+UNIX_SHM_BASE, n);
}else{
rc = SQLITE_OK;
}
}
/* Get the local shared locks */
if( rc==SQLITE_OK ){
p->sharedMask |= mask;
}
}else{
/* Make sure no sibling connections hold locks that will block this
** lock. If any do, return SQLITE_BUSY right away.
*/
for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
if( (pX->exclMask & mask)!=0 || (pX->sharedMask & mask)!=0 ){
rc = SQLITE_BUSY;
break;
}
}
/* Get the exclusive locks at the system level. Then if successful
** also mark the local connection as being locked.
*/
if( rc==SQLITE_OK ){
rc = unixShmSystemLock(pDbFd, F_WRLCK, ofst+UNIX_SHM_BASE, n);
if( rc==SQLITE_OK ){
assert( (p->sharedMask & mask)==0 );
p->exclMask |= mask;
}
}
}
sqlite3_mutex_leave(pShmNode->pShmMutex);
OSTRACE(("SHM-LOCK shmid-%d, pid-%d got %03x,%03x\n",
p->id, osGetpid(0), p->sharedMask, p->exclMask));
return rc;
}
/*
** Implement a memory barrier or memory fence on shared memory.
**
** All loads and stores begun before the barrier must complete before
** any load or store begun after the barrier.
*/
static void unixShmBarrier(
sqlite3_file *fd /* Database file holding the shared memory */
){
UNUSED_PARAMETER(fd);
sqlite3MemoryBarrier(); /* compiler-defined memory barrier */
assert( fd->pMethods->xLock==nolockLock
|| unixFileMutexNotheld((unixFile*)fd)
);
unixEnterMutex(); /* Also mutex, for redundancy */
unixLeaveMutex();
}
/*
** Close a connection to shared-memory. Delete the underlying
** storage if deleteFlag is true.
**
** If there is no shared memory associated with the connection then this
** routine is a harmless no-op.
*/
static int unixShmUnmap(
sqlite3_file *fd, /* The underlying database file */
int deleteFlag /* Delete shared-memory if true */
){
unixShm *p; /* The connection to be closed */
unixShmNode *pShmNode; /* The underlying shared-memory file */
unixShm **pp; /* For looping over sibling connections */
unixFile *pDbFd; /* The underlying database file */
pDbFd = (unixFile*)fd;
p = pDbFd->pShm;
if( p==0 ) return SQLITE_OK;
pShmNode = p->pShmNode;
assert( pShmNode==pDbFd->pInode->pShmNode );
assert( pShmNode->pInode==pDbFd->pInode );
/* Remove connection p from the set of connections associated
** with pShmNode */
sqlite3_mutex_enter(pShmNode->pShmMutex);
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
static int proxyClose(sqlite3_file*);
static int proxyLock(sqlite3_file*, int);
static int proxyUnlock(sqlite3_file*, int);
static int proxyCheckReservedLock(sqlite3_file*, int*);
IOMETHODS(
proxyIoFinder, /* Finder function name */
proxyIoMethods, /* sqlite3_io_methods object name */
1, /* shared memory is disabled */
proxyClose, /* xClose method */
proxyLock, /* xLock method */
proxyUnlock, /* xUnlock method */
proxyCheckReservedLock, /* xCheckReservedLock method */
0 /* xShmMap method */
)
#endif
/* nfs lockd on OSX 10.3+ doesn't clear write locks when a read lock is set */
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
IOMETHODS(
nfsIoFinder, /* Finder function name */
nfsIoMethods, /* sqlite3_io_methods object name */
1, /* shared memory is disabled */
unixClose, /* xClose method */
unixLock, /* xLock method */
nfsUnlock, /* xUnlock method */
unixCheckReservedLock, /* xCheckReservedLock method */
0 /* xShmMap method */
)
#endif
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
/*
** This "finder" function attempts to determine the best locking strategy
** for the database file "filePath". It then returns the sqlite3_io_methods
** object that implements that strategy.
**
** This is for MacOSX only.
*/
static const sqlite3_io_methods *autolockIoFinderImpl(
const char *filePath, /* name of the database file */
unixFile *pNew /* open file object for the database file */
){
static const struct Mapping {
const char *zFilesystem; /* Filesystem type name */
const sqlite3_io_methods *pMethods; /* Appropriate locking method */
} aMap[] = {
{ "hfs", &posixIoMethods },
{ "ufs", &posixIoMethods },
{ "afpfs", &afpIoMethods },
{ "smbfs", &afpIoMethods },
{ "webdav", &nolockIoMethods },
{ 0, 0 }
};
int i;
struct statfs fsInfo;
struct flock lockInfo;
if( !filePath ){
/* If filePath==NULL that means we are dealing with a transient file
** that does not need to be locked. */
return &nolockIoMethods;
}
if( statfs(filePath, &fsInfo) != -1 ){
if( fsInfo.f_flags & MNT_RDONLY ){
return &nolockIoMethods;
}
for(i=0; aMap[i].zFilesystem; i++){
if( strcmp(fsInfo.f_fstypename, aMap[i].zFilesystem)==0 ){
return aMap[i].pMethods;
}
}
}
/* Default case. Handles, amongst others, "nfs".
** Test byte-range lock using fcntl(). If the call succeeds,
** assume that the file-system supports POSIX style locks.
*/
lockInfo.l_len = 1;
lockInfo.l_start = 0;
lockInfo.l_whence = SEEK_SET;
lockInfo.l_type = F_RDLCK;
if( osFcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) {
if( strcmp(fsInfo.f_fstypename, "nfs")==0 ){
return &nfsIoMethods;
} else {
return &posixIoMethods;
}
}else{
return &dotlockIoMethods;
}
}
static const sqlite3_io_methods
*(*const autolockIoFinder)(const char*,unixFile*) = autolockIoFinderImpl;
#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
#if OS_VXWORKS
/*
** This "finder" function for VxWorks checks to see if posix advisory
** locking works. If it does, then that is what is used. If it does not
** work, then fallback to named semaphore locking.
*/
static const sqlite3_io_methods *vxworksIoFinderImpl(
const char *filePath, /* name of the database file */
unixFile *pNew /* the open file object */
){
struct flock lockInfo;
if( !filePath ){
/* If filePath==NULL that means we are dealing with a transient file
** that does not need to be locked. */
return &nolockIoMethods;
}
/* Test if fcntl() is supported and use POSIX style locks.
** Otherwise fall back to the named semaphore method.
*/
lockInfo.l_len = 1;
lockInfo.l_start = 0;
lockInfo.l_whence = SEEK_SET;
lockInfo.l_type = F_RDLCK;
if( osFcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) {
return &posixIoMethods;
}else{
return &semIoMethods;
}
}
static const sqlite3_io_methods
*(*const vxworksIoFinder)(const char*,unixFile*) = vxworksIoFinderImpl;
#endif /* OS_VXWORKS */
/*
** An abstract type for a pointer to an IO method finder function:
*/
typedef const sqlite3_io_methods *(*finder_type)(const char*,unixFile*);
/****************************************************************************
**************************** sqlite3_vfs methods ****************************
**
** This division contains the implementation of methods on the
** sqlite3_vfs object.
*/
/*
** Initialize the contents of the unixFile structure pointed to by pId.
*/
static int fillInUnixFile(
sqlite3_vfs *pVfs, /* Pointer to vfs object */
int h, /* Open file descriptor of file being opened */
sqlite3_file *pId, /* Write to the unixFile structure here */
const char *zFilename, /* Name of the file being opened */
int ctrlFlags /* Zero or more UNIXFILE_* values */
){
const sqlite3_io_methods *pLockingStyle;
unixFile *pNew = (unixFile *)pId;
int rc = SQLITE_OK;
assert( pNew->pInode==NULL );
/* No locking occurs in temporary files */
assert( zFilename!=0 || (ctrlFlags & UNIXFILE_NOLOCK)!=0 );
OSTRACE(("OPEN %-3d %s\n", h, zFilename));
pNew->h = h;
pNew->pVfs = pVfs;
pNew->zPath = zFilename;
pNew->ctrlFlags = (u8)ctrlFlags;
#if SQLITE_MAX_MMAP_SIZE>0
pNew->mmapSizeMax = sqlite3GlobalConfig.szMmap;
#define osCreateFile2 ((HANDLE(WINAPI*)(LPCWSTR,DWORD,DWORD,DWORD, \
LPCREATEFILE2_EXTENDED_PARAMETERS))aSyscall[68].pCurrent)
#if SQLITE_OS_WINRT && !defined(SQLITE_OMIT_LOAD_EXTENSION)
{ "LoadPackagedLibrary", (SYSCALL)LoadPackagedLibrary, 0 },
#else
{ "LoadPackagedLibrary", (SYSCALL)0, 0 },
#endif
#define osLoadPackagedLibrary ((HMODULE(WINAPI*)(LPCWSTR, \
DWORD))aSyscall[69].pCurrent)
#if SQLITE_OS_WINRT
{ "GetTickCount64", (SYSCALL)GetTickCount64, 0 },
#else
{ "GetTickCount64", (SYSCALL)0, 0 },
#endif
#define osGetTickCount64 ((ULONGLONG(WINAPI*)(VOID))aSyscall[70].pCurrent)
#if SQLITE_OS_WINRT
{ "GetNativeSystemInfo", (SYSCALL)GetNativeSystemInfo, 0 },
#else
{ "GetNativeSystemInfo", (SYSCALL)0, 0 },
#endif
#define osGetNativeSystemInfo ((VOID(WINAPI*)( \
LPSYSTEM_INFO))aSyscall[71].pCurrent)
#if defined(SQLITE_WIN32_HAS_ANSI)
{ "OutputDebugStringA", (SYSCALL)OutputDebugStringA, 0 },
#else
{ "OutputDebugStringA", (SYSCALL)0, 0 },
#endif
#define osOutputDebugStringA ((VOID(WINAPI*)(LPCSTR))aSyscall[72].pCurrent)
#if defined(SQLITE_WIN32_HAS_WIDE)
{ "OutputDebugStringW", (SYSCALL)OutputDebugStringW, 0 },
#else
{ "OutputDebugStringW", (SYSCALL)0, 0 },
#endif
#define osOutputDebugStringW ((VOID(WINAPI*)(LPCWSTR))aSyscall[73].pCurrent)
{ "GetProcessHeap", (SYSCALL)GetProcessHeap, 0 },
#define osGetProcessHeap ((HANDLE(WINAPI*)(VOID))aSyscall[74].pCurrent)
#if SQLITE_OS_WINRT && (!defined(SQLITE_OMIT_WAL) || SQLITE_MAX_MMAP_SIZE>0)
{ "CreateFileMappingFromApp", (SYSCALL)CreateFileMappingFromApp, 0 },
#else
{ "CreateFileMappingFromApp", (SYSCALL)0, 0 },
#endif
#define osCreateFileMappingFromApp ((HANDLE(WINAPI*)(HANDLE, \
LPSECURITY_ATTRIBUTES,ULONG,ULONG64,LPCWSTR))aSyscall[75].pCurrent)
/*
** NOTE: On some sub-platforms, the InterlockedCompareExchange "function"
** is really just a macro that uses a compiler intrinsic (e.g. x64).
** So do not try to make this is into a redefinable interface.
*/
#if defined(InterlockedCompareExchange)
{ "InterlockedCompareExchange", (SYSCALL)0, 0 },
#define osInterlockedCompareExchange InterlockedCompareExchange
#else
{ "InterlockedCompareExchange", (SYSCALL)InterlockedCompareExchange, 0 },
#define osInterlockedCompareExchange ((LONG(WINAPI*)(LONG \
SQLITE_WIN32_VOLATILE*, LONG,LONG))aSyscall[76].pCurrent)
#endif /* defined(InterlockedCompareExchange) */
#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && SQLITE_WIN32_USE_UUID
{ "UuidCreate", (SYSCALL)UuidCreate, 0 },
#else
{ "UuidCreate", (SYSCALL)0, 0 },
#endif
#define osUuidCreate ((RPC_STATUS(RPC_ENTRY*)(UUID*))aSyscall[77].pCurrent)
#if !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && SQLITE_WIN32_USE_UUID
{ "UuidCreateSequential", (SYSCALL)UuidCreateSequential, 0 },
#else
{ "UuidCreateSequential", (SYSCALL)0, 0 },
#endif
#define osUuidCreateSequential \
((RPC_STATUS(RPC_ENTRY*)(UUID*))aSyscall[78].pCurrent)
#if !defined(SQLITE_NO_SYNC) && SQLITE_MAX_MMAP_SIZE>0
{ "FlushViewOfFile", (SYSCALL)FlushViewOfFile, 0 },
#else
{ "FlushViewOfFile", (SYSCALL)0, 0 },
#endif
#define osFlushViewOfFile \
((BOOL(WINAPI*)(LPCVOID,SIZE_T))aSyscall[79].pCurrent)
}; /* End of the overrideable system calls */
/*
** This is the xSetSystemCall() method of sqlite3_vfs for all of the
** "win32" VFSes. Return SQLITE_OK opon successfully updating the
** system call pointer, or SQLITE_NOTFOUND if there is no configurable
** system call named zName.
*/
static int winSetSystemCall(
sqlite3_vfs *pNotUsed, /* The VFS pointer. Not used */
const char *zName, /* Name of system call to override */
sqlite3_syscall_ptr pNewFunc /* Pointer to new system call value */
){
unsigned int i;
int rc = SQLITE_NOTFOUND;
UNUSED_PARAMETER(pNotUsed);
if( zName==0 ){
/* If no zName is given, restore all system calls to their default
** settings and return NULL
*/
rc = SQLITE_OK;
for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
if( aSyscall[i].pDefault ){
aSyscall[i].pCurrent = aSyscall[i].pDefault;
}
}
}else{
/* If zName is specified, operate on only the one system call
** specified.
*/
for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
if( strcmp(zName, aSyscall[i].zName)==0 ){
static HANDLE sleepObj = NULL;
#endif
SQLITE_API void sqlite3_win32_sleep(DWORD milliseconds){
#if SQLITE_OS_WINRT
if ( sleepObj==NULL ){
sleepObj = osCreateEventExW(NULL, NULL, CREATE_EVENT_MANUAL_RESET,
SYNCHRONIZE);
}
assert( sleepObj!=NULL );
osWaitForSingleObjectEx(sleepObj, milliseconds, FALSE);
#else
osSleep(milliseconds);
#endif
}
#if SQLITE_MAX_WORKER_THREADS>0 && !SQLITE_OS_WINCE && !SQLITE_OS_WINRT && \
SQLITE_THREADSAFE>0
SQLITE_PRIVATE DWORD sqlite3Win32Wait(HANDLE hObject){
DWORD rc;
while( (rc = osWaitForSingleObjectEx(hObject, INFINITE,
TRUE))==WAIT_IO_COMPLETION ){}
return rc;
}
#endif
/*
** Return true (non-zero) if we are running under WinNT, Win2K, WinXP,
** or WinCE. Return false (zero) for Win95, Win98, or WinME.
**
** Here is an interesting observation: Win95, Win98, and WinME lack
** the LockFileEx() API. But we can still statically link against that
** API as long as we don't call it when running Win95/98/ME. A call to
** this routine is used to determine if the host is Win95/98/ME or
** WinNT/2K/XP so that we will know whether or not we can safely call
** the LockFileEx() API.
*/
#if !SQLITE_WIN32_GETVERSIONEX
# define osIsNT() (1)
#elif SQLITE_OS_WINCE || SQLITE_OS_WINRT || !defined(SQLITE_WIN32_HAS_ANSI)
# define osIsNT() (1)
#elif !defined(SQLITE_WIN32_HAS_WIDE)
# define osIsNT() (0)
#else
# define osIsNT() ((sqlite3_os_type==2) || sqlite3_win32_is_nt())
#endif
/*
** This function determines if the machine is running a version of Windows
** based on the NT kernel.
*/
SQLITE_API int sqlite3_win32_is_nt(void){
#if SQLITE_OS_WINRT
/*
** NOTE: The WinRT sub-platform is always assumed to be based on the NT
** kernel.
*/
return 1;
#elif SQLITE_WIN32_GETVERSIONEX
if( osInterlockedCompareExchange(&sqlite3_os_type, 0, 0)==0 ){
#if defined(SQLITE_WIN32_HAS_ANSI)
OSVERSIONINFOA sInfo;
sInfo.dwOSVersionInfoSize = sizeof(sInfo);
osGetVersionExA(&sInfo);
osInterlockedCompareExchange(&sqlite3_os_type,
(sInfo.dwPlatformId == VER_PLATFORM_WIN32_NT) ? 2 : 1, 0);
#elif defined(SQLITE_WIN32_HAS_WIDE)
OSVERSIONINFOW sInfo;
sInfo.dwOSVersionInfoSize = sizeof(sInfo);
osGetVersionExW(&sInfo);
osInterlockedCompareExchange(&sqlite3_os_type,
(sInfo.dwPlatformId == VER_PLATFORM_WIN32_NT) ? 2 : 1, 0);
#endif
}
return osInterlockedCompareExchange(&sqlite3_os_type, 2, 2)==2;
#elif SQLITE_TEST
return osInterlockedCompareExchange(&sqlite3_os_type, 2, 2)==2;
#else
/*
** NOTE: All sub-platforms where the GetVersionEx[AW] functions are
** deprecated are always assumed to be based on the NT kernel.
*/
return 1;
#endif
}
#ifdef SQLITE_WIN32_MALLOC
/*
** Allocate nBytes of memory.
*/
static void *winMemMalloc(int nBytes){
HANDLE hHeap;
void *p;
winMemAssertMagic();
hHeap = winMemGetHeap();
assert( hHeap!=0 );
assert( hHeap!=INVALID_HANDLE_VALUE );
#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_MALLOC_VALIDATE)
assert( osHeapValidate(hHeap, SQLITE_WIN32_HEAP_FLAGS, NULL) );
#endif
assert( nBytes>=0 );
p = osHeapAlloc(hHeap, SQLITE_WIN32_HEAP_FLAGS, (SIZE_T)nBytes);
if( !p ){
sqlite3_log(SQLITE_NOMEM, "failed to HeapAlloc %u bytes (%lu), heap=%p",
nBytes, osGetLastError(), (void*)hHeap);
}
return p;
}
/*
** Free memory.
*/
static void winMemFree(void *pPrior){
HANDLE hHeap;
winMemAssertMagic();
hHeap = winMemGetHeap();
assert( hHeap!=0 );
assert( hHeap!=INVALID_HANDLE_VALUE );
#if !SQLITE_OS_WINRT && defined(SQLITE_WIN32_MALLOC_VALIDATE)
assert( osHeapValidate(hHeap, SQLITE_WIN32_HEAP_FLAGS, pPrior) );
#endif
if( !pPrior ) return; /* Passing NULL to HeapFree is undefined. */
if( !osHeapFree(hHeap, SQLITE_WIN32_HEAP_FLAGS, pPrior) ){
sqlite3_log(SQLITE_NOMEM, "failed to HeapFree block %p (%lu), heap=%p",
pPrior, osGetLastError(), (void*)hHeap);
}
}
/*
** Change the size of an existing memory allocation
*/
static void *winMemRealloc(void *pPrior, int nBytes){
HANDLE hHeap;
void *p;
#ifndef SQLITE_OMIT_WAL
/*
** Helper functions to obtain and relinquish the global mutex. The
** global mutex is used to protect the winLockInfo objects used by
** this file, all of which may be shared by multiple threads.
**
** Function winShmMutexHeld() is used to assert() that the global mutex
** is held when required. This function is only used as part of assert()
** statements. e.g.
**
** winShmEnterMutex()
** assert( winShmMutexHeld() );
** winShmLeaveMutex()
*/
static sqlite3_mutex *winBigLock = 0;
static void winShmEnterMutex(void){
sqlite3_mutex_enter(winBigLock);
}
static void winShmLeaveMutex(void){
sqlite3_mutex_leave(winBigLock);
}
#ifndef NDEBUG
static int winShmMutexHeld(void) {
return sqlite3_mutex_held(winBigLock);
}
#endif
/*
** Object used to represent a single file opened and mmapped to provide
** shared memory. When multiple threads all reference the same
** log-summary, each thread has its own winFile object, but they all
** point to a single instance of this object. In other words, each
** log-summary is opened only once per process.
**
** winShmMutexHeld() must be true when creating or destroying
** this object or while reading or writing the following fields:
**
** nRef
** pNext
**
** The following fields are read-only after the object is created:
**
** fid
** zFilename
**
** Either winShmNode.mutex must be held or winShmNode.nRef==0 and
** winShmMutexHeld() is true when reading or writing any other field
** in this structure.
**
*/
struct winShmNode {
sqlite3_mutex *mutex; /* Mutex to access this object */
char *zFilename; /* Name of the file */
winFile hFile; /* File handle from winOpen */
int szRegion; /* Size of shared-memory regions */
int nRegion; /* Size of array apRegion */
u8 isReadonly; /* True if read-only */
u8 isUnlocked; /* True if no DMS lock held */
struct ShmRegion {
HANDLE hMap; /* File handle from CreateFileMapping */
void *pMap;
} *aRegion;
DWORD lastErrno; /* The Windows errno from the last I/O error */
int nRef; /* Number of winShm objects pointing to this */
winShm *pFirst; /* All winShm objects pointing to this */
winShmNode *pNext; /* Next in list of all winShmNode objects */
#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
u8 nextShmId; /* Next available winShm.id value */
#endif
};
/*
** A global array of all winShmNode objects.
**
** The winShmMutexHeld() must be true while reading or writing this list.
*/
static winShmNode *winShmNodeList = 0;
/*
** Structure used internally by this VFS to record the state of an
** open shared memory connection.
**
** The following fields are initialized when this object is created and
** are read-only thereafter:
**
** winShm.pShmNode
** winShm.id
**
** All other fields are read/write. The winShm.pShmNode->mutex must be held
** while accessing any read/write fields.
*/
struct winShm {
winShmNode *pShmNode; /* The underlying winShmNode object */
winShm *pNext; /* Next winShm with the same winShmNode */
u8 hasMutex; /* True if holding the winShmNode mutex */
u16 sharedMask; /* Mask of shared locks held */
u16 exclMask; /* Mask of exclusive locks held */
#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
u8 id; /* Id of this connection with its winShmNode */
#endif
};
/*
** Constants used for locking
*/
#define WIN_SHM_BASE ((22+SQLITE_SHM_NLOCK)*4) /* first lock byte */
#define WIN_SHM_DMS (WIN_SHM_BASE+SQLITE_SHM_NLOCK) /* deadman switch */
/*
** Apply advisory locks for all n bytes beginning at ofst.
*/
#define WINSHM_UNLCK 1
#define WINSHM_RDLCK 2
#define WINSHM_WRLCK 3
static int winShmSystemLock(
winShmNode *pFile, /* Apply locks to this open shared-memory segment */
int lockType, /* WINSHM_UNLCK, WINSHM_RDLCK, or WINSHM_WRLCK */
int ofst, /* Offset to first byte to be locked/unlocked */
int nByte /* Number of bytes to lock or unlock */
){
int rc = 0; /* Result code form Lock/UnlockFileEx() */
/* Access to the winShmNode object is serialized by the caller */
assert( pFile->nRef==0 || sqlite3_mutex_held(pFile->mutex) );
OSTRACE(("SHM-LOCK file=%p, lock=%d, offset=%d, size=%d\n",
pFile->hFile.h, lockType, ofst, nByte));
/* Release/Acquire the system-level lock */
if( lockType==WINSHM_UNLCK ){
rc = winUnlockFile(&pFile->hFile.h, ofst, 0, nByte, 0);
}else{
/* Initialize the locking parameters */
DWORD dwFlags = LOCKFILE_FAIL_IMMEDIATELY;
if( lockType == WINSHM_WRLCK ) dwFlags |= LOCKFILE_EXCLUSIVE_LOCK;
rc = winLockFile(&pFile->hFile.h, dwFlags, ofst, 0, nByte, 0);
}
if( rc!= 0 ){
rc = SQLITE_OK;
}else{
pFile->lastErrno = osGetLastError();
rc = SQLITE_BUSY;
}
OSTRACE(("SHM-LOCK file=%p, func=%s, errno=%lu, rc=%s\n",
pFile->hFile.h, (lockType == WINSHM_UNLCK) ? "winUnlockFile" :
"winLockFile", pFile->lastErrno, sqlite3ErrName(rc)));
return rc;
}
/* Forward references to VFS methods */
static int winOpen(sqlite3_vfs*,const char*,sqlite3_file*,int,int*);
static int winDelete(sqlite3_vfs *,const char*,int);
/*
** Purge the winShmNodeList list of all entries with winShmNode.nRef==0.
**
** This is not a VFS shared-memory method; it is a utility function called
** by VFS shared-memory methods.
*/
static void winShmPurge(sqlite3_vfs *pVfs, int deleteFlag){
winShmNode **pp;
winShmNode *p;
assert( winShmMutexHeld() );
OSTRACE(("SHM-PURGE pid=%lu, deleteFlag=%d\n",
osGetCurrentProcessId(), deleteFlag));
pp = &winShmNodeList;
while( (p = *pp)!=0 ){
if( p->nRef==0 ){
int i;
if( p->mutex ){ sqlite3_mutex_free(p->mutex); }
for(i=0; i<p->nRegion; i++){
BOOL bRc = osUnmapViewOfFile(p->aRegion[i].pMap);
OSTRACE(("SHM-PURGE-UNMAP pid=%lu, region=%d, rc=%s\n",
osGetCurrentProcessId(), i, bRc ? "ok" : "failed"));
UNUSED_VARIABLE_VALUE(bRc);
bRc = osCloseHandle(p->aRegion[i].hMap);
OSTRACE(("SHM-PURGE-CLOSE pid=%lu, region=%d, rc=%s\n",
osGetCurrentProcessId(), i, bRc ? "ok" : "failed"));
UNUSED_VARIABLE_VALUE(bRc);
}
if( p->hFile.h!=NULL && p->hFile.h!=INVALID_HANDLE_VALUE ){
SimulateIOErrorBenign(1);
winClose((sqlite3_file *)&p->hFile);
SimulateIOErrorBenign(0);
}
if( deleteFlag ){
SimulateIOErrorBenign(1);
sqlite3BeginBenignMalloc();
winDelete(pVfs, p->zFilename, 0);
sqlite3EndBenignMalloc();
SimulateIOErrorBenign(0);
}
*pp = p->pNext;
sqlite3_free(p->aRegion);
sqlite3_free(p);
}else{
pp = &p->pNext;
}
}
}
/*
** The DMS lock has not yet been taken on shm file pShmNode. Attempt to
** take it now. Return SQLITE_OK if successful, or an SQLite error
** code otherwise.
**
** If the DMS cannot be locked because this is a readonly_shm=1
** connection and no other process already holds a lock, return
** SQLITE_READONLY_CANTINIT and set pShmNode->isUnlocked=1.
*/
static int winLockSharedMemory(winShmNode *pShmNode){
int rc = winShmSystemLock(pShmNode, WINSHM_WRLCK, WIN_SHM_DMS, 1);
if( rc==SQLITE_OK ){
if( pShmNode->isReadonly ){
pShmNode->isUnlocked = 1;
winShmSystemLock(pShmNode, WINSHM_UNLCK, WIN_SHM_DMS, 1);
return SQLITE_READONLY_CANTINIT;
}else if( winTruncate((sqlite3_file*)&pShmNode->hFile, 0) ){
winShmSystemLock(pShmNode, WINSHM_UNLCK, WIN_SHM_DMS, 1);
return winLogError(SQLITE_IOERR_SHMOPEN, osGetLastError(),
"winLockSharedMemory", pShmNode->zFilename);
}
}
if( rc==SQLITE_OK ){
winShmSystemLock(pShmNode, WINSHM_UNLCK, WIN_SHM_DMS, 1);
}
return winShmSystemLock(pShmNode, WINSHM_RDLCK, WIN_SHM_DMS, 1);
}
/*
** Open the shared-memory area associated with database file pDbFd.
**
** When opening a new shared-memory file, if no other instances of that
** file are currently open, in this process or in other processes, then
** the file must be truncated to zero length or have its header cleared.
*/
static int winOpenSharedMemory(winFile *pDbFd){
struct winShm *p; /* The connection to be opened */
winShmNode *pShmNode = 0; /* The underlying mmapped file */
int rc = SQLITE_OK; /* Result code */
winShmNode *pNew; /* Newly allocated winShmNode */
int nName; /* Size of zName in bytes */
assert( pDbFd->pShm==0 ); /* Not previously opened */
/* Allocate space for the new sqlite3_shm object. Also speculatively
** allocate space for a new winShmNode and filename.
*/
p = sqlite3MallocZero( sizeof(*p) );
if( p==0 ) return SQLITE_IOERR_NOMEM_BKPT;
nName = sqlite3Strlen30(pDbFd->zPath);
pNew = sqlite3MallocZero( sizeof(*pShmNode) + nName + 17 );
if( pNew==0 ){
sqlite3_free(p);
return SQLITE_IOERR_NOMEM_BKPT;
}
pNew->zFilename = (char*)&pNew[1];
sqlite3_snprintf(nName+15, pNew->zFilename, "%s-shm", pDbFd->zPath);
sqlite3FileSuffix3(pDbFd->zPath, pNew->zFilename);
/* Look to see if there is an existing winShmNode that can be used.
** If no matching winShmNode currently exists, create a new one.
*/
winShmEnterMutex();
for(pShmNode = winShmNodeList; pShmNode; pShmNode=pShmNode->pNext){
/* TBD need to come up with better match here. Perhaps
** use FILE_ID_BOTH_DIR_INFO Structure.
*/
if( sqlite3StrICmp(pShmNode->zFilename, pNew->zFilename)==0 ) break;
}
if( pShmNode ){
sqlite3_free(pNew);
}else{
winShmSystemLock(pShmNode, WINSHM_UNLCK, WIN_SHM_DMS, 1);
winShmPurge(pDbFd->pVfs, 0); /* This call frees pShmNode if required */
sqlite3_free(p);
sqlite3_free(pNew);
winShmLeaveMutex();
return rc;
}
/*
** Close a connection to shared-memory. Delete the underlying
** storage if deleteFlag is true.
*/
static int winShmUnmap(
sqlite3_file *fd, /* Database holding shared memory */
int deleteFlag /* Delete after closing if true */
){
winFile *pDbFd; /* Database holding shared-memory */
winShm *p; /* The connection to be closed */
winShmNode *pShmNode; /* The underlying shared-memory file */
winShm **pp; /* For looping over sibling connections */
pDbFd = (winFile*)fd;
p = pDbFd->pShm;
if( p==0 ) return SQLITE_OK;
pShmNode = p->pShmNode;
/* Remove connection p from the set of connections associated
** with pShmNode */
sqlite3_mutex_enter(pShmNode->mutex);
for(pp=&pShmNode->pFirst; (*pp)!=p; pp = &(*pp)->pNext){}
*pp = p->pNext;
/* Free the connection p */
sqlite3_free(p);
pDbFd->pShm = 0;
sqlite3_mutex_leave(pShmNode->mutex);
/* If pShmNode->nRef has reached 0, then close the underlying
** shared-memory file, too */
winShmEnterMutex();
assert( pShmNode->nRef>0 );
pShmNode->nRef--;
if( pShmNode->nRef==0 ){
winShmPurge(pDbFd->pVfs, deleteFlag);
}
winShmLeaveMutex();
return SQLITE_OK;
}
/*
** Change the lock state for a shared-memory segment.
*/
static int winShmLock(
sqlite3_file *fd, /* Database file holding the shared memory */
int ofst, /* First lock to acquire or release */
int n, /* Number of locks to acquire or release */
int flags /* What to do with the lock */
){
winFile *pDbFd = (winFile*)fd; /* Connection holding shared memory */
winShm *p = pDbFd->pShm; /* The shared memory being locked */
winShm *pX; /* For looping over all siblings */
winShmNode *pShmNode = p->pShmNode;
int rc = SQLITE_OK; /* Result code */
u16 mask; /* Mask of locks to take or release */
assert( ofst>=0 && ofst+n<=SQLITE_SHM_NLOCK );
assert( n>=1 );
assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED)
|| flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE)
|| flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED)
|| flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );
mask = (u16)((1U<<(ofst+n)) - (1U<<ofst));
assert( n>1 || mask==(1<<ofst) );
sqlite3_mutex_enter(pShmNode->mutex);
if( flags & SQLITE_SHM_UNLOCK ){
u16 allMask = 0; /* Mask of locks held by siblings */
/* See if any siblings hold this same lock */
for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
if( pX==p ) continue;
assert( (pX->exclMask & (p->exclMask|p->sharedMask))==0 );
allMask |= pX->sharedMask;
}
/* Unlock the system-level locks */
if( (mask & allMask)==0 ){
rc = winShmSystemLock(pShmNode, WINSHM_UNLCK, ofst+WIN_SHM_BASE, n);
}else{
rc = SQLITE_OK;
}
/* Undo the local locks */
if( rc==SQLITE_OK ){
p->exclMask &= ~mask;
p->sharedMask &= ~mask;
}
}else if( flags & SQLITE_SHM_SHARED ){
u16 allShared = 0; /* Union of locks held by connections other than "p" */
/* Find out which shared locks are already held by sibling connections.
** If any sibling already holds an exclusive lock, go ahead and return
** SQLITE_BUSY.
*/
for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
if( (pX->exclMask & mask)!=0 ){
rc = SQLITE_BUSY;
break;
}
allShared |= pX->sharedMask;
}
/* Get shared locks at the system level, if necessary */
if( rc==SQLITE_OK ){
if( (allShared & mask)==0 ){
rc = winShmSystemLock(pShmNode, WINSHM_RDLCK, ofst+WIN_SHM_BASE, n);
}else{
rc = SQLITE_OK;
}
}
/* Get the local shared locks */
if( rc==SQLITE_OK ){
p->sharedMask |= mask;
}
}else{
/* Make sure no sibling connections hold locks that will block this
** lock. If any do, return SQLITE_BUSY right away.
*/
for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
if( (pX->exclMask & mask)!=0 || (pX->sharedMask & mask)!=0 ){
rc = SQLITE_BUSY;
break;
}
}
/* Get the exclusive locks at the system level. Then if successful
** also mark the local connection as being locked.
*/
if( rc==SQLITE_OK ){
rc = winShmSystemLock(pShmNode, WINSHM_WRLCK, ofst+WIN_SHM_BASE, n);
if( rc==SQLITE_OK ){
assert( (p->sharedMask & mask)==0 );
p->exclMask |= mask;
}
}
}
sqlite3_mutex_leave(pShmNode->mutex);
OSTRACE(("SHM-LOCK pid=%lu, id=%d, sharedMask=%03x, exclMask=%03x, rc=%s\n",
osGetCurrentProcessId(), p->id, p->sharedMask, p->exclMask,
sqlite3ErrName(rc)));
return rc;
}
/*
** Implement a memory barrier or memory fence on shared memory.
**
** All loads and stores begun before the barrier must complete before
** any load or store begun after the barrier.
*/
static void winShmBarrier(
sqlite3_file *fd /* Database holding the shared memory */
){
UNUSED_PARAMETER(fd);
sqlite3MemoryBarrier(); /* compiler-defined memory barrier */
winShmEnterMutex(); /* Also mutex, for redundancy */
winShmLeaveMutex();
}
/*
** This function is called to obtain a pointer to region iRegion of the
** shared-memory associated with the database file fd. Shared-memory regions
** are numbered starting from zero. Each shared-memory region is szRegion
** bytes in size.
**
** If an error occurs, an error code is returned and *pp is set to NULL.
**
** Otherwise, if the isWrite parameter is 0 and the requested shared-memory
** region has not been allocated (by any client, including one running in a
** separate process), then *pp is set to NULL and SQLITE_OK returned. If
** isWrite is non-zero and the requested shared-memory region has not yet
** been allocated, it is allocated by this function.
**
** If the shared-memory region has already been allocated or is allocated by
** this call as described above, then it is mapped into this processes
** address space (if it is not already), *pp is set to point to the mapped
** memory and SQLITE_OK returned.
*/
static int winShmMap(
sqlite3_file *fd, /* Handle open on database file */
int iRegion, /* Region to retrieve */
int szRegion, /* Size of regions */
int isWrite, /* True to extend file if necessary */
void volatile **pp /* OUT: Mapped memory */
){
winFile *pDbFd = (winFile*)fd;
winShm *pShm = pDbFd->pShm;
winShmNode *pShmNode;
DWORD protect = PAGE_READWRITE;
DWORD flags = FILE_MAP_WRITE | FILE_MAP_READ;
int rc = SQLITE_OK;
if( !pShm ){
rc = winOpenSharedMemory(pDbFd);
if( rc!=SQLITE_OK ) return rc;
pShm = pDbFd->pShm;
}
pShmNode = pShm->pShmNode;
sqlite3_mutex_enter(pShmNode->mutex);
if( pShmNode->isUnlocked ){
rc = winLockSharedMemory(pShmNode);
if( rc!=SQLITE_OK ) goto shmpage_out;
pShmNode->isUnlocked = 0;
}
assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 );
if( pShmNode->nRegion<=iRegion ){
struct ShmRegion *apNew; /* New aRegion[] array */
int nByte = (iRegion+1)*szRegion; /* Minimum required file size */
sqlite3_int64 sz; /* Current size of wal-index file */
pShmNode->szRegion = szRegion;
/* The requested region is not mapped into this processes address space.
** Check to see if it has been allocated (i.e. if the wal-index file is
** large enough to contain the requested region).
*/
rc = winFileSize((sqlite3_file *)&pShmNode->hFile, &sz);
if( rc!=SQLITE_OK ){
rc = winLogError(SQLITE_IOERR_SHMSIZE, osGetLastError(),
"winShmMap1", pDbFd->zPath);
goto shmpage_out;
}
if( sz<nByte ){
/* The requested memory region does not exist. If isWrite is set to
** zero, exit early. *pp will be set to NULL and SQLITE_OK returned.
**
** Alternatively, if isWrite is non-zero, use ftruncate() to allocate
** the requested memory region.
*/
if( !isWrite ) goto shmpage_out;
rc = winTruncate((sqlite3_file *)&pShmNode->hFile, nByte);
if( rc!=SQLITE_OK ){
rc = winLogError(SQLITE_IOERR_SHMSIZE, osGetLastError(),
"winShmMap2", pDbFd->zPath);
goto shmpage_out;
}
}
/* Map the requested memory region into this processes address space. */
apNew = (struct ShmRegion *)sqlite3_realloc64(
pShmNode->aRegion, (iRegion+1)*sizeof(apNew[0])
);
if( !apNew ){
rc = SQLITE_IOERR_NOMEM_BKPT;
goto shmpage_out;
}
pShmNode->aRegion = apNew;
if( pShmNode->isReadonly ){
protect = PAGE_READONLY;
flags = FILE_MAP_READ;
}
while( pShmNode->nRegion<=iRegion ){
HANDLE hMap = NULL; /* file-mapping handle */
void *pMap = 0; /* Mapped memory region */
#if SQLITE_OS_WINRT
hMap = osCreateFileMappingFromApp(pShmNode->hFile.h,
NULL, protect, nByte, NULL
);
#if 0
int sqlite3PagerTrace=1; /* True to enable tracing */
#define sqlite3DebugPrintf printf
#define PAGERTRACE(X) if( sqlite3PagerTrace ){ sqlite3DebugPrintf X; }
#else
#define PAGERTRACE(X)
#endif
/*
** The following two macros are used within the PAGERTRACE() macros above
** to print out file-descriptors.
**
** PAGERID() takes a pointer to a Pager struct as its argument. The
** associated file-descriptor is returned. FILEHANDLEID() takes an sqlite3_file
** struct as its argument.
*/
#define PAGERID(p) (SQLITE_PTR_TO_INT(p->fd))
#define FILEHANDLEID(fd) (SQLITE_PTR_TO_INT(fd))
/*
** The Pager.eState variable stores the current 'state' of a pager. A
** pager may be in any one of the seven states shown in the following
** state diagram.
**
** OPEN <------+------+
** | | |
** V | |
** +---------> READER-------+ |
** | | |
** | V |
** |<-------WRITER_LOCKED------> ERROR
** | | ^
** | V |
** |<------WRITER_CACHEMOD-------->|
** | | |
** | V |
** |<-------WRITER_DBMOD---------->|
** | | |
** | V |
** +<------WRITER_FINISHED-------->+
**
**
** List of state transitions and the C [function] that performs each:
**
** OPEN -> READER [sqlite3PagerSharedLock]
** READER -> OPEN [pager_unlock]
**
** READER -> WRITER_LOCKED [sqlite3PagerBegin]
** WRITER_LOCKED -> WRITER_CACHEMOD [pager_open_journal]
** WRITER_CACHEMOD -> WRITER_DBMOD [syncJournal]
** WRITER_DBMOD -> WRITER_FINISHED [sqlite3PagerCommitPhaseOne]
** WRITER_*** -> READER [pager_end_transaction]
**
** WRITER_*** -> ERROR [pager_error]
** ERROR -> OPEN [pager_unlock]
**
**
** OPEN:
**
** The pager starts up in this state. Nothing is guaranteed in this
** state - the file may or may not be locked and the database size is
** unknown. The database may not be read or written.
**
** * No read or write transaction is active.
** * Any lock, or no lock at all, may be held on the database file.
** * The dbSize, dbOrigSize and dbFileSize variables may not be trusted.
**
** READER:
**
** In this state all the requirements for reading the database in
** rollback (non-WAL) mode are met. Unless the pager is (or recently
** was) in exclusive-locking mode, a user-level read transaction is
** open. The database size is known in this state.
**
** A connection running with locking_mode=normal enters this state when
** it opens a read-transaction on the database and returns to state
** OPEN after the read-transaction is completed. However a connection
** running in locking_mode=exclusive (including temp databases) remains in
** this state even after the read-transaction is closed. The only way
** a locking_mode=exclusive connection can transition from READER to OPEN
** is via the ERROR state (see below).
**
** * A read transaction may be active (but a write-transaction cannot).
** * A SHARED or greater lock is held on the database file.
** * The dbSize variable may be trusted (even if a user-level read
** transaction is not active). The dbOrigSize and dbFileSize variables
** may not be trusted at this point.
** * If the database is a WAL database, then the WAL connection is open.
** * Even if a read-transaction is not open, it is guaranteed that
** there is no hot-journal in the file-system.
**
** WRITER_LOCKED:
**
** The pager moves to this state from READER when a write-transaction
** is first opened on the database. In WRITER_LOCKED state, all locks
** required to start a write-transaction are held, but no actual
** modifications to the cache or database have taken place.
**
** In rollback mode, a RESERVED or (if the transaction was opened with
** BEGIN EXCLUSIVE) EXCLUSIVE lock is obtained on the database file when
** moving to this state, but the journal file is not written to or opened
** to in this state. If the transaction is committed or rolled back while
** in WRITER_LOCKED state, all that is required is to unlock the database
** file.
**
** IN WAL mode, WalBeginWriteTransaction() is called to lock the log file.
** If the connection is running with locking_mode=exclusive, an attempt
** is made to obtain an EXCLUSIVE lock on the database file.
**
** * A write transaction is active.
** * If the connection is open in rollback-mode, a RESERVED or greater
** lock is held on the database file.
** * If the connection is open in WAL-mode, a WAL write transaction
** is open (i.e. sqlite3WalBeginWriteTransaction() has been successfully
** called).
** * The dbSize, dbOrigSize and dbFileSize variables are all valid.
** * The contents of the pager cache have not been modified.
** * The journal file may or may not be open.
** * Nothing (not even the first header) has been written to the journal.
**
** WRITER_CACHEMOD:
** memory.
**
** In other cases, the error is returned to the b-tree layer. The b-tree
** layer then attempts a rollback operation. If the error condition
** persists, the pager enters the ERROR state via condition (1) above.
**
** Condition (3) is necessary because it can be triggered by a read-only
** statement executed within a transaction. In this case, if the error
** code were simply returned to the user, the b-tree layer would not
** automatically attempt a rollback, as it assumes that an error in a
** read-only statement cannot leave the pager in an internally inconsistent
** state.
**
** * The Pager.errCode variable is set to something other than SQLITE_OK.
** * There are one or more outstanding references to pages (after the
** last reference is dropped the pager should move back to OPEN state).
** * The pager is not an in-memory pager.
**
**
** Notes:
**
** * A pager is never in WRITER_DBMOD or WRITER_FINISHED state if the
** connection is open in WAL mode. A WAL connection is always in one
** of the first four states.
**
** * Normally, a connection open in exclusive mode is never in PAGER_OPEN
** state. There are two exceptions: immediately after exclusive-mode has
** been turned on (and before any read or write transactions are
** executed), and when the pager is leaving the "error state".
**
** * See also: assert_pager_state().
*/
#define PAGER_OPEN 0
#define PAGER_READER 1
#define PAGER_WRITER_LOCKED 2
#define PAGER_WRITER_CACHEMOD 3
#define PAGER_WRITER_DBMOD 4
#define PAGER_WRITER_FINISHED 5
#define PAGER_ERROR 6
/*
** The Pager.eLock variable is almost always set to one of the
** following locking-states, according to the lock currently held on
** the database file: NO_LOCK, SHARED_LOCK, RESERVED_LOCK or EXCLUSIVE_LOCK.
** This variable is kept up to date as locks are taken and released by
** the pagerLockDb() and pagerUnlockDb() wrappers.
**
** If the VFS xLock() or xUnlock() returns an error other than SQLITE_BUSY
** (i.e. one of the SQLITE_IOERR subtypes), it is not clear whether or not
** the operation was successful. In these circumstances pagerLockDb() and
** pagerUnlockDb() take a conservative approach - eLock is always updated
** when unlocking the file, and only updated when locking the file if the
** VFS call is successful. This way, the Pager.eLock variable may be set
** to a less exclusive (lower) value than the lock that is actually held
** at the system level, but it is never set to a more exclusive value.
**
** This is usually safe. If an xUnlock fails or appears to fail, there may
** be a few redundant xLock() calls or a lock may be held for longer than
** required, but nothing really goes wrong.
**
** The exception is when the database file is unlocked as the pager moves
** from ERROR to OPEN state. At this point there may be a hot-journal file
** in the file-system that needs to be rolled back (as part of an OPEN->SHARED
** transition, by the same pager or any other). If the call to xUnlock()
** fails at this point and the pager is left holding an EXCLUSIVE lock, this
** can confuse the call to xCheckReservedLock() call made later as part
** of hot-journal detection.
**
** xCheckReservedLock() is defined as returning true "if there is a RESERVED
** lock held by this process or any others". So xCheckReservedLock may
** return true because the caller itself is holding an EXCLUSIVE lock (but
** doesn't know it because of a previous error in xUnlock). If this happens
** a hot-journal may be mistaken for a journal being created by an active
** transaction in another process, causing SQLite to read from the database
** without rolling it back.
**
** To work around this, if a call to xUnlock() fails when unlocking the
** database in the ERROR state, Pager.eLock is set to UNKNOWN_LOCK. It
** is only changed back to a real locking state after a successful call
** to xLock(EXCLUSIVE). Also, the code to do the OPEN->SHARED state transition
** omits the check for a hot-journal if Pager.eLock is set to UNKNOWN_LOCK
** lock. Instead, it assumes a hot-journal exists and obtains an EXCLUSIVE
** lock on the database file before attempting to roll it back. See function
** PagerSharedLock() for more detail.
**
** Pager.eLock may only be set to UNKNOWN_LOCK when the pager is in
** PAGER_OPEN state.
*/
#define UNKNOWN_LOCK (EXCLUSIVE_LOCK+1)
/*
** A macro used for invoking the codec if there is one
*/
#ifdef SQLITE_HAS_CODEC
# define CODEC1(P,D,N,X,E) \
if( P->xCodec && P->xCodec(P->pCodec,D,N,X)==0 ){ E; }
# define CODEC2(P,D,N,X,E,O) \
if( P->xCodec==0 ){ O=(char*)D; }else \
if( (O=(char*)(P->xCodec(P->pCodec,D,N,X)))==0 ){ E; }
#else
# define CODEC1(P,D,N,X,E) /* NO-OP */
# define CODEC2(P,D,N,X,E,O) O=(char*)D
#endif
/*
** The maximum allowed sector size. 64KiB. If the xSectorsize() method
** returns a value larger than this, then MAX_SECTOR_SIZE is used instead.
** This could conceivably cause corruption following a power failure on
** such a system. This is currently an undocumented limit.
*/
#define MAX_SECTOR_SIZE 0x10000
/*
** An instance of the following structure is allocated for each active
** savepoint and statement transaction in the system. All such structures
** are stored in the Pager.aSavepoint[] array, which is allocated and
** resized using sqlite3Realloc().
**
** When a savepoint is created, the PagerSavepoint.iHdrOffset field is
** set to 0. If a journal-header is written into the main journal while
** Discard the entire contents of the in-memory page-cache.
*/
static void pager_reset(Pager *pPager){
pPager->iDataVersion++;
sqlite3BackupRestart(pPager->pBackup);
sqlite3PcacheClear(pPager->pPCache);
}
/*
** Return the pPager->iDataVersion value
*/
SQLITE_PRIVATE u32 sqlite3PagerDataVersion(Pager *pPager){
return pPager->iDataVersion;
}
/*
** Free all structures in the Pager.aSavepoint[] array and set both
** Pager.aSavepoint and Pager.nSavepoint to zero. Close the sub-journal
** if it is open and the pager is not in exclusive mode.
*/
static void releaseAllSavepoints(Pager *pPager){
int ii; /* Iterator for looping through Pager.aSavepoint */
for(ii=0; ii<pPager->nSavepoint; ii++){
sqlite3BitvecDestroy(pPager->aSavepoint[ii].pInSavepoint);
}
if( !pPager->exclusiveMode || sqlite3JournalIsInMemory(pPager->sjfd) ){
sqlite3OsClose(pPager->sjfd);
}
sqlite3_free(pPager->aSavepoint);
pPager->aSavepoint = 0;
pPager->nSavepoint = 0;
pPager->nSubRec = 0;
}
/*
** Set the bit number pgno in the PagerSavepoint.pInSavepoint
** bitvecs of all open savepoints. Return SQLITE_OK if successful
** or SQLITE_NOMEM if a malloc failure occurs.
*/
static int addToSavepointBitvecs(Pager *pPager, Pgno pgno){
int ii; /* Loop counter */
int rc = SQLITE_OK; /* Result code */
for(ii=0; ii<pPager->nSavepoint; ii++){
PagerSavepoint *p = &pPager->aSavepoint[ii];
if( pgno<=p->nOrig ){
rc |= sqlite3BitvecSet(p->pInSavepoint, pgno);
testcase( rc==SQLITE_NOMEM );
assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
}
}
return rc;
}
/*
** This function is a no-op if the pager is in exclusive mode and not
** in the ERROR state. Otherwise, it switches the pager to PAGER_OPEN
** state.
**
** If the pager is not in exclusive-access mode, the database file is
** completely unlocked. If the file is unlocked and the file-system does
** not exhibit the UNDELETABLE_WHEN_OPEN property, the journal file is
** closed (if it is open).
**
** If the pager is in ERROR state when this function is called, the
** contents of the pager cache are discarded before switching back to
** the OPEN state. Regardless of whether the pager is in exclusive-mode
** or not, any journal file left in the file-system will be treated
** as a hot-journal and rolled back the next time a read-transaction
** is opened (by this or by any other connection).
*/
static void pager_unlock(Pager *pPager){
assert( pPager->eState==PAGER_READER
|| pPager->eState==PAGER_OPEN
|| pPager->eState==PAGER_ERROR
);
sqlite3BitvecDestroy(pPager->pInJournal);
pPager->pInJournal = 0;
releaseAllSavepoints(pPager);
if( pagerUseWal(pPager) ){
assert( !isOpen(pPager->jfd) );
sqlite3WalEndReadTransaction(pPager->pWal);
pPager->eState = PAGER_OPEN;
}else if( !pPager->exclusiveMode ){
int rc; /* Error code returned by pagerUnlockDb() */
int iDc = isOpen(pPager->fd)?sqlite3OsDeviceCharacteristics(pPager->fd):0;
/* If the operating system support deletion of open files, then
** close the journal file when dropping the database lock. Otherwise
** another connection with journal_mode=delete might delete the file
** out from under us.
*/
assert( (PAGER_JOURNALMODE_MEMORY & 5)!=1 );
assert( (PAGER_JOURNALMODE_OFF & 5)!=1 );
assert( (PAGER_JOURNALMODE_WAL & 5)!=1 );
assert( (PAGER_JOURNALMODE_DELETE & 5)!=1 );
assert( (PAGER_JOURNALMODE_TRUNCATE & 5)==1 );
assert( (PAGER_JOURNALMODE_PERSIST & 5)==1 );
if( 0==(iDc & SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN)
|| 1!=(pPager->journalMode & 5)
){
sqlite3OsClose(pPager->jfd);
}
/* If the pager is in the ERROR state and the call to unlock the database
** file fails, set the current lock to UNKNOWN_LOCK. See the comment
** above the #define for UNKNOWN_LOCK for an explanation of why this
** is necessary.
*/
rc = pagerUnlockDb(pPager, NO_LOCK);
if( rc!=SQLITE_OK && pPager->eState==PAGER_ERROR ){
pPager->eLock = UNKNOWN_LOCK;
}
/* The pager state may be changed from PAGER_ERROR to PAGER_OPEN here
** without clearing the error code. This is intentional - the error
** code is cleared and the cache reset in the block below.
*/
** thought. If a power failure occurs while the journal is being written,
** it could cause invalid data to be written into the journal. We need to
** detect this invalid data (with high probability) and ignore it.
*/
if( pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){
assert( !isSavepnt );
return SQLITE_DONE;
}
if( pgno>(Pgno)pPager->dbSize || sqlite3BitvecTest(pDone, pgno) ){
return SQLITE_OK;
}
if( isMainJrnl ){
rc = read32bits(jfd, (*pOffset)-4, &cksum);
if( rc ) return rc;
if( !isSavepnt && pager_cksum(pPager, (u8*)aData)!=cksum ){
return SQLITE_DONE;
}
}
/* If this page has already been played back before during the current
** rollback, then don't bother to play it back again.
*/
if( pDone && (rc = sqlite3BitvecSet(pDone, pgno))!=SQLITE_OK ){
return rc;
}
/* When playing back page 1, restore the nReserve setting
*/
if( pgno==1 && pPager->nReserve!=((u8*)aData)[20] ){
pPager->nReserve = ((u8*)aData)[20];
pagerReportSize(pPager);
}
/* If the pager is in CACHEMOD state, then there must be a copy of this
** page in the pager cache. In this case just update the pager cache,
** not the database file. The page is left marked dirty in this case.
**
** An exception to the above rule: If the database is in no-sync mode
** and a page is moved during an incremental vacuum then the page may
** not be in the pager cache. Later: if a malloc() or IO error occurs
** during a Movepage() call, then the page may not be in the cache
** either. So the condition described in the above paragraph is not
** assert()able.
**
** If in WRITER_DBMOD, WRITER_FINISHED or OPEN state, then we update the
** pager cache if it exists and the main file. The page is then marked
** not dirty. Since this code is only executed in PAGER_OPEN state for
** a hot-journal rollback, it is guaranteed that the page-cache is empty
** if the pager is in OPEN state.
**
** Ticket #1171: The statement journal might contain page content that is
** different from the page content at the start of the transaction.
** This occurs when a page is changed prior to the start of a statement
** then changed again within the statement. When rolling back such a
** statement we must not write to the original database unless we know
** for certain that original page contents are synced into the main rollback
** journal. Otherwise, a power loss might leave modified data in the
** database file without an entry in the rollback journal that can
** restore the database to its original form. Two conditions must be
** met before writing to the database files. (1) the database must be
** locked. (2) we know that the original page content is fully synced
** in the main journal either because the page is not in cache or else
** the page is marked as needSync==0.
**
** 2008-04-14: When attempting to vacuum a corrupt database file, it
** is possible to fail a statement on a database that does not yet exist.
** Do not attempt to write if database file has never been opened.
*/
if( pagerUseWal(pPager) ){
pPg = 0;
}else{
pPg = sqlite3PagerLookup(pPager, pgno);
}
assert( pPg || !MEMDB );
assert( pPager->eState!=PAGER_OPEN || pPg==0 || pPager->tempFile );
PAGERTRACE(("PLAYBACK %d page %d hash(%08x) %s\n",
PAGERID(pPager), pgno, pager_datahash(pPager->pageSize, (u8*)aData),
(isMainJrnl?"main-journal":"sub-journal")
));
if( isMainJrnl ){
isSynced = pPager->noSync || (*pOffset <= pPager->journalHdr);
}else{
isSynced = (pPg==0 || 0==(pPg->flags & PGHDR_NEED_SYNC));
}
if( isOpen(pPager->fd)
&& (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
&& isSynced
){
i64 ofst = (pgno-1)*(i64)pPager->pageSize;
testcase( !isSavepnt && pPg!=0 && (pPg->flags&PGHDR_NEED_SYNC)!=0 );
assert( !pagerUseWal(pPager) );
/* Write the data read from the journal back into the database file.
** This is usually safe even for an encrypted database - as the data
** was encrypted before it was written to the journal file. The exception
** is if the data was just read from an in-memory sub-journal. In that
** case it must be encrypted here before it is copied into the database
** file. */
#ifdef SQLITE_HAS_CODEC
if( !jrnlEnc ){
CODEC2(pPager, aData, pgno, 7, rc=SQLITE_NOMEM_BKPT, aData);
rc = sqlite3OsWrite(pPager->fd, (u8 *)aData, pPager->pageSize, ofst);
CODEC1(pPager, aData, pgno, 3, rc=SQLITE_NOMEM_BKPT);
}else
#endif
rc = sqlite3OsWrite(pPager->fd, (u8 *)aData, pPager->pageSize, ofst);
if( pgno>pPager->dbFileSize ){
pPager->dbFileSize = pgno;
}
if( pPager->pBackup ){
#ifdef SQLITE_HAS_CODEC
if( jrnlEnc ){
CODEC1(pPager, aData, pgno, 3, rc=SQLITE_NOMEM_BKPT);
sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)aData);
CODEC2(pPager, aData, pgno, 7, rc=SQLITE_NOMEM_BKPT,aData);
}else
#endif
sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)aData);
}
}else if( !isMainJrnl && pPg==0 ){
setGetterMethod(pPager);
/* memset(pPager->aHash, 0, sizeof(pPager->aHash)); */
/* pPager->szMmap = SQLITE_DEFAULT_MMAP_SIZE // will be set by btree.c */
*ppPager = pPager;
return SQLITE_OK;
}
/*
** This function is called after transitioning from PAGER_UNLOCK to
** PAGER_SHARED state. It tests if there is a hot journal present in
** the file-system for the given pager. A hot journal is one that
** needs to be played back. According to this function, a hot-journal
** file exists if the following criteria are met:
**
** * The journal file exists in the file system, and
** * No process holds a RESERVED or greater lock on the database file, and
** * The database file itself is greater than 0 bytes in size, and
** * The first byte of the journal file exists and is not 0x00.
**
** If the current size of the database file is 0 but a journal file
** exists, that is probably an old journal left over from a prior
** database with the same name. In this case the journal file is
** just deleted using OsDelete, *pExists is set to 0 and SQLITE_OK
** is returned.
**
** This routine does not check if there is a master journal filename
** at the end of the file. If there is, and that master journal file
** does not exist, then the journal file is not really hot. In this
** case this routine will return a false-positive. The pager_playback()
** routine will discover that the journal file is not really hot and
** will not roll it back.
**
** If a hot-journal file is found to exist, *pExists is set to 1 and
** SQLITE_OK returned. If no hot-journal file is present, *pExists is
** set to 0 and SQLITE_OK returned. If an IO error occurs while trying
** to determine whether or not a hot-journal file exists, the IO error
** code is returned and the value of *pExists is undefined.
*/
static int hasHotJournal(Pager *pPager, int *pExists){
sqlite3_vfs * const pVfs = pPager->pVfs;
int rc = SQLITE_OK; /* Return code */
int exists = 1; /* True if a journal file is present */
int jrnlOpen = !!isOpen(pPager->jfd);
assert( pPager->useJournal );
assert( isOpen(pPager->fd) );
assert( pPager->eState==PAGER_OPEN );
assert( jrnlOpen==0 || ( sqlite3OsDeviceCharacteristics(pPager->jfd) &
SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
));
*pExists = 0;
if( !jrnlOpen ){
rc = sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &exists);
}
if( rc==SQLITE_OK && exists ){
int locked = 0; /* True if some process holds a RESERVED lock */
/* Race condition here: Another process might have been holding the
** the RESERVED lock and have a journal open at the sqlite3OsAccess()
** call above, but then delete the journal and drop the lock before
** we get to the following sqlite3OsCheckReservedLock() call. If that
** is the case, this routine might think there is a hot journal when
** in fact there is none. This results in a false-positive which will
** be dealt with by the playback routine. Ticket #3883.
*/
rc = sqlite3OsCheckReservedLock(pPager->fd, &locked);
if( rc==SQLITE_OK && !locked ){
Pgno nPage; /* Number of pages in database file */
assert( pPager->tempFile==0 );
rc = pagerPagecount(pPager, &nPage);
if( rc==SQLITE_OK ){
/* If the database is zero pages in size, that means that either (1) the
** journal is a remnant from a prior database with the same name where
** the database file but not the journal was deleted, or (2) the initial
** transaction that populates a new database is being rolled back.
** In either case, the journal file can be deleted. However, take care
** not to delete the journal file if it is already open due to
** journal_mode=PERSIST.
*/
if( nPage==0 && !jrnlOpen ){
sqlite3BeginBenignMalloc();
if( pagerLockDb(pPager, RESERVED_LOCK)==SQLITE_OK ){
sqlite3OsDelete(pVfs, pPager->zJournal, 0);
if( !pPager->exclusiveMode ) pagerUnlockDb(pPager, SHARED_LOCK);
}
sqlite3EndBenignMalloc();
}else{
/* The journal file exists and no other connection has a reserved
** or greater lock on the database file. Now check that there is
** at least one non-zero bytes at the start of the journal file.
** If there is, then we consider this journal to be hot. If not,
** it can be ignored.
*/
if( !jrnlOpen ){
int f = SQLITE_OPEN_READONLY|SQLITE_OPEN_MAIN_JOURNAL;
rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &f);
}
if( rc==SQLITE_OK ){
u8 first = 0;
rc = sqlite3OsRead(pPager->jfd, (void *)&first, 1, 0);
if( rc==SQLITE_IOERR_SHORT_READ ){
rc = SQLITE_OK;
}
if( !jrnlOpen ){
sqlite3OsClose(pPager->jfd);
}
*pExists = (first!=0);
}else if( rc==SQLITE_CANTOPEN ){
/* If we cannot open the rollback journal file in order to see if
** it has a zero header, that might be due to an I/O error, or
** it might be due to the race condition described above and in
** ticket #3883. Either way, assume that the journal is hot.
** This might be a false positive. But if it is, then the
** automatic journal playback and recovery mechanism will deal
** with it under an EXCLUSIVE lock where we do not need to
** worry so much with race conditions.
*/
*pExists = 1;
rc = SQLITE_OK;
}
}
}
}
}
return rc;
if( memcmp(&pWal->hdr.aSalt, &aFrame[8], 8)!=0 ){
return 0;
}
/* A frame is only valid if the page number is creater than zero.
*/
pgno = sqlite3Get4byte(&aFrame[0]);
if( pgno==0 ){
return 0;
}
/* A frame is only valid if a checksum of the WAL header,
** all prior frams, the first 16 bytes of this frame-header,
** and the frame-data matches the checksum in the last 8
** bytes of this frame-header.
*/
nativeCksum = (pWal->hdr.bigEndCksum==SQLITE_BIGENDIAN);
walChecksumBytes(nativeCksum, aFrame, 8, aCksum, aCksum);
walChecksumBytes(nativeCksum, aData, pWal->szPage, aCksum, aCksum);
if( aCksum[0]!=sqlite3Get4byte(&aFrame[16])
|| aCksum[1]!=sqlite3Get4byte(&aFrame[20])
){
/* Checksum failed. */
return 0;
}
/* If we reach this point, the frame is valid. Return the page number
** and the new database size.
*/
*piPage = pgno;
*pnTruncate = sqlite3Get4byte(&aFrame[4]);
return 1;
}
#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
/*
** Names of locks. This routine is used to provide debugging output and is not
** a part of an ordinary build.
*/
static const char *walLockName(int lockIdx){
if( lockIdx==WAL_WRITE_LOCK ){
return "WRITE-LOCK";
}else if( lockIdx==WAL_CKPT_LOCK ){
return "CKPT-LOCK";
}else if( lockIdx==WAL_RECOVER_LOCK ){
return "RECOVER-LOCK";
}else{
static char zName[15];
sqlite3_snprintf(sizeof(zName), zName, "READ-LOCK[%d]",
lockIdx-WAL_READ_LOCK(0));
return zName;
}
}
#endif /*defined(SQLITE_TEST) || defined(SQLITE_DEBUG) */
/*
** Set or release locks on the WAL. Locks are either shared or exclusive.
** A lock cannot be moved directly between shared and exclusive - it must go
** through the unlocked state first.
**
** In locking_mode=EXCLUSIVE, all of these routines become no-ops.
*/
static int walLockShared(Wal *pWal, int lockIdx){
int rc;
if( pWal->exclusiveMode ) return SQLITE_OK;
rc = sqlite3OsShmLock(pWal->pDbFd, lockIdx, 1,
SQLITE_SHM_LOCK | SQLITE_SHM_SHARED);
WALTRACE(("WAL%p: acquire SHARED-%s %s\n", pWal,
walLockName(lockIdx), rc ? "failed" : "ok"));
VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && rc!=SQLITE_BUSY); )
return rc;
}
static void walUnlockShared(Wal *pWal, int lockIdx){
if( pWal->exclusiveMode ) return;
(void)sqlite3OsShmLock(pWal->pDbFd, lockIdx, 1,
SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED);
WALTRACE(("WAL%p: release SHARED-%s\n", pWal, walLockName(lockIdx)));
}
static int walLockExclusive(Wal *pWal, int lockIdx, int n){
int rc;
if( pWal->exclusiveMode ) return SQLITE_OK;
rc = sqlite3OsShmLock(pWal->pDbFd, lockIdx, n,
SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE);
WALTRACE(("WAL%p: acquire EXCLUSIVE-%s cnt=%d %s\n", pWal,
walLockName(lockIdx), n, rc ? "failed" : "ok"));
VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && rc!=SQLITE_BUSY); )
return rc;
}
static void walUnlockExclusive(Wal *pWal, int lockIdx, int n){
if( pWal->exclusiveMode ) return;
(void)sqlite3OsShmLock(pWal->pDbFd, lockIdx, n,
SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE);
WALTRACE(("WAL%p: release EXCLUSIVE-%s cnt=%d\n", pWal,
walLockName(lockIdx), n));
}
/*
** Compute a hash on a page number. The resulting hash value must land
** between 0 and (HASHTABLE_NSLOT-1). The walHashNext() function advances
** the hash to the next value in the event of a collision.
*/
static int walHash(u32 iPage){
assert( iPage>0 );
assert( (HASHTABLE_NSLOT & (HASHTABLE_NSLOT-1))==0 );
return (iPage*HASHTABLE_HASH_1) & (HASHTABLE_NSLOT-1);
}
static int walNextHash(int iPriorHash){
return (iPriorHash+1)&(HASHTABLE_NSLOT-1);
}
/*
** An instance of the WalHashLoc object is used to describe the location
** of a page hash table in the wal-index. This becomes the return value
** from walHashGet().
*/
typedef struct WalHashLoc WalHashLoc;
struct WalHashLoc {
volatile ht_slot *aHash; /* Start of the wal-index hash table */
volatile u32 *aPgno; /* aPgno[1] is the page of first frame indexed */
/* Write the aPgno[] array entry and the hash-table slot. */
nCollide = idx;
for(iKey=walHash(iPage); sLoc.aHash[iKey]; iKey=walNextHash(iKey)){
if( (nCollide--)==0 ) return SQLITE_CORRUPT_BKPT;
}
sLoc.aPgno[idx] = iPage;
sLoc.aHash[iKey] = (ht_slot)idx;
#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
/* Verify that the number of entries in the hash table exactly equals
** the number of entries in the mapping region.
*/
{
int i; /* Loop counter */
int nEntry = 0; /* Number of entries in the hash table */
for(i=0; i<HASHTABLE_NSLOT; i++){ if( sLoc.aHash[i] ) nEntry++; }
assert( nEntry==idx );
}
/* Verify that the every entry in the mapping region is reachable
** via the hash table. This turns out to be a really, really expensive
** thing to check, so only do this occasionally - not on every
** iteration.
*/
if( (idx&0x3ff)==0 ){
int i; /* Loop counter */
for(i=1; i<=idx; i++){
for(iKey=walHash(sLoc.aPgno[i]);
sLoc.aHash[iKey];
iKey=walNextHash(iKey)){
if( sLoc.aHash[iKey]==i ) break;
}
assert( sLoc.aHash[iKey]==i );
}
}
#endif /* SQLITE_ENABLE_EXPENSIVE_ASSERT */
}
return rc;
}
/*
** Recover the wal-index by reading the write-ahead log file.
**
** This routine first tries to establish an exclusive lock on the
** wal-index to prevent other threads/processes from doing anything
** with the WAL or wal-index while recovery is running. The
** WAL_RECOVER_LOCK is also held so that other threads will know
** that this thread is running recovery. If unable to establish
** the necessary locks, this routine returns SQLITE_BUSY.
*/
static int walIndexRecover(Wal *pWal){
int rc; /* Return Code */
i64 nSize; /* Size of log file */
u32 aFrameCksum[2] = {0, 0};
int iLock; /* Lock offset to lock for checkpoint */
/* Obtain an exclusive lock on all byte in the locking range not already
** locked by the caller. The caller is guaranteed to have locked the
** WAL_WRITE_LOCK byte, and may have also locked the WAL_CKPT_LOCK byte.
** If successful, the same bytes that are locked here are unlocked before
** this function returns.
*/
assert( pWal->ckptLock==1 || pWal->ckptLock==0 );
assert( WAL_ALL_BUT_WRITE==WAL_WRITE_LOCK+1 );
assert( WAL_CKPT_LOCK==WAL_ALL_BUT_WRITE );
assert( pWal->writeLock );
iLock = WAL_ALL_BUT_WRITE + pWal->ckptLock;
rc = walLockExclusive(pWal, iLock, WAL_READ_LOCK(0)-iLock);
if( rc==SQLITE_OK ){
rc = walLockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
if( rc!=SQLITE_OK ){
walUnlockExclusive(pWal, iLock, WAL_READ_LOCK(0)-iLock);
}
}
if( rc ){
return rc;
}
WALTRACE(("WAL%p: recovery begin...\n", pWal));
memset(&pWal->hdr, 0, sizeof(WalIndexHdr));
rc = sqlite3OsFileSize(pWal->pWalFd, &nSize);
if( rc!=SQLITE_OK ){
goto recovery_error;
}
if( nSize>WAL_HDRSIZE ){
u8 aBuf[WAL_HDRSIZE]; /* Buffer to load WAL header into */
u8 *aFrame = 0; /* Malloc'd buffer to load entire frame */
int szFrame; /* Number of bytes in buffer aFrame[] */
u8 *aData; /* Pointer to data part of aFrame buffer */
int iFrame; /* Index of last frame read */
i64 iOffset; /* Next offset to read from log file */
int szPage; /* Page size according to the log */
u32 magic; /* Magic value read from WAL header */
u32 version; /* Magic value read from WAL header */
int isValid; /* True if this frame is valid */
/* Read in the WAL header. */
rc = sqlite3OsRead(pWal->pWalFd, aBuf, WAL_HDRSIZE, 0);
if( rc!=SQLITE_OK ){
goto recovery_error;
}
/* If the database page size is not a power of two, or is greater than
** SQLITE_MAX_PAGE_SIZE, conclude that the WAL file contains no valid
** data. Similarly, if the 'magic' value is invalid, ignore the whole
** WAL file.
*/
magic = sqlite3Get4byte(&aBuf[0]);
szPage = sqlite3Get4byte(&aBuf[8]);
if( (magic&0xFFFFFFFE)!=WAL_MAGIC
|| szPage&(szPage-1)
|| szPage>SQLITE_MAX_PAGE_SIZE
|| szPage<512
){
goto finished;
}
pWal->hdr.bigEndCksum = (u8)(magic&0x00000001);
}
/*
** Attempt to start a read transaction. This might fail due to a race or
** other transient condition. When that happens, it returns WAL_RETRY to
** indicate to the caller that it is safe to retry immediately.
**
** On success return SQLITE_OK. On a permanent failure (such an
** I/O error or an SQLITE_BUSY because another process is running
** recovery) return a positive error code.
**
** The useWal parameter is true to force the use of the WAL and disable
** the case where the WAL is bypassed because it has been completely
** checkpointed. If useWal==0 then this routine calls walIndexReadHdr()
** to make a copy of the wal-index header into pWal->hdr. If the
** wal-index header has changed, *pChanged is set to 1 (as an indication
** to the caller that the local page cache is obsolete and needs to be
** flushed.) When useWal==1, the wal-index header is assumed to already
** be loaded and the pChanged parameter is unused.
**
** The caller must set the cnt parameter to the number of prior calls to
** this routine during the current read attempt that returned WAL_RETRY.
** This routine will start taking more aggressive measures to clear the
** race conditions after multiple WAL_RETRY returns, and after an excessive
** number of errors will ultimately return SQLITE_PROTOCOL. The
** SQLITE_PROTOCOL return indicates that some other process has gone rogue
** and is not honoring the locking protocol. There is a vanishingly small
** chance that SQLITE_PROTOCOL could be returned because of a run of really
** bad luck when there is lots of contention for the wal-index, but that
** possibility is so small that it can be safely neglected, we believe.
**
** On success, this routine obtains a read lock on
** WAL_READ_LOCK(pWal->readLock). The pWal->readLock integer is
** in the range 0 <= pWal->readLock < WAL_NREADER. If pWal->readLock==(-1)
** that means the Wal does not hold any read lock. The reader must not
** access any database page that is modified by a WAL frame up to and
** including frame number aReadMark[pWal->readLock]. The reader will
** use WAL frames up to and including pWal->hdr.mxFrame if pWal->readLock>0
** Or if pWal->readLock==0, then the reader will ignore the WAL
** completely and get all content directly from the database file.
** If the useWal parameter is 1 then the WAL will never be ignored and
** this routine will always set pWal->readLock>0 on success.
** When the read transaction is completed, the caller must release the
** lock on WAL_READ_LOCK(pWal->readLock) and set pWal->readLock to -1.
**
** This routine uses the nBackfill and aReadMark[] fields of the header
** to select a particular WAL_READ_LOCK() that strives to let the
** checkpoint process do as much work as possible. This routine might
** update values of the aReadMark[] array in the header, but if it does
** so it takes care to hold an exclusive lock on the corresponding
** WAL_READ_LOCK() while changing values.
*/
static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
volatile WalCkptInfo *pInfo; /* Checkpoint information in wal-index */
u32 mxReadMark; /* Largest aReadMark[] value */
int mxI; /* Index of largest aReadMark[] value */
int i; /* Loop counter */
int rc = SQLITE_OK; /* Return code */
u32 mxFrame; /* Wal frame to lock to */
assert( pWal->readLock<0 ); /* Not currently locked */
/* useWal may only be set for read/write connections */
assert( (pWal->readOnly & WAL_SHM_RDONLY)==0 || useWal==0 );
/* Take steps to avoid spinning forever if there is a protocol error.
**
** Circumstances that cause a RETRY should only last for the briefest
** instances of time. No I/O or other system calls are done while the
** locks are held, so the locks should not be held for very long. But
** if we are unlucky, another process that is holding a lock might get
** paged out or take a page-fault that is time-consuming to resolve,
** during the few nanoseconds that it is holding the lock. In that case,
** it might take longer than normal for the lock to free.
**
** After 5 RETRYs, we begin calling sqlite3OsSleep(). The first few
** calls to sqlite3OsSleep() have a delay of 1 microsecond. Really this
** is more of a scheduler yield than an actual delay. But on the 10th
** an subsequent retries, the delays start becoming longer and longer,
** so that on the 100th (and last) RETRY we delay for 323 milliseconds.
** The total delay time before giving up is less than 10 seconds.
*/
if( cnt>5 ){
int nDelay = 1; /* Pause time in microseconds */
if( cnt>100 ){
VVA_ONLY( pWal->lockError = 1; )
return SQLITE_PROTOCOL;
}
if( cnt>=10 ) nDelay = (cnt-9)*(cnt-9)*39;
sqlite3OsSleep(pWal->pVfs, nDelay);
}
if( !useWal ){
assert( rc==SQLITE_OK );
if( pWal->bShmUnreliable==0 ){
rc = walIndexReadHdr(pWal, pChanged);
}
if( rc==SQLITE_BUSY ){
/* If there is not a recovery running in another thread or process
** then convert BUSY errors to WAL_RETRY. If recovery is known to
** be running, convert BUSY to BUSY_RECOVERY. There is a race here
** which might cause WAL_RETRY to be returned even if BUSY_RECOVERY
** would be technically correct. But the race is benign since with
** WAL_RETRY this routine will be called again and will probably be
** right on the second iteration.
*/
if( pWal->apWiData[0]==0 ){
/* This branch is taken when the xShmMap() method returns SQLITE_BUSY.
** We assume this is a transient condition, so return WAL_RETRY. The
** xShmMap() implementation used by the default unix and win32 VFS
** modules may return SQLITE_BUSY due to a race condition in the
** code that determines whether or not the shared-memory region
** must be zeroed before the requested page is returned.
*/
rc = WAL_RETRY;
}else if( SQLITE_OK==(rc = walLockShared(pWal, WAL_RECOVER_LOCK)) ){
walUnlockShared(pWal, WAL_RECOVER_LOCK);
rc = WAL_RETRY;
}else if( rc==SQLITE_BUSY ){
rc = SQLITE_BUSY_RECOVERY;
}
u16 nFree; /* Number of free bytes on the page */
u16 nCell; /* Number of cells on this page, local and ovfl */
u16 maskPage; /* Mask for page offset */
u16 aiOvfl[4]; /* Insert the i-th overflow cell before the aiOvfl-th
** non-overflow cell */
u8 *apOvfl[4]; /* Pointers to the body of overflow cells */
BtShared *pBt; /* Pointer to BtShared that this page is part of */
u8 *aData; /* Pointer to disk image of the page data */
u8 *aDataEnd; /* One byte past the end of usable data */
u8 *aCellIdx; /* The cell index area */
u8 *aDataOfst; /* Same as aData for leaves. aData+4 for interior */
DbPage *pDbPage; /* Pager page handle */
u16 (*xCellSize)(MemPage*,u8*); /* cellSizePtr method */
void (*xParseCell)(MemPage*,u8*,CellInfo*); /* btreeParseCell method */
};
/*
** A linked list of the following structures is stored at BtShared.pLock.
** Locks are added (or upgraded from READ_LOCK to WRITE_LOCK) when a cursor
** is opened on the table with root page BtShared.iTable. Locks are removed
** from this list when a transaction is committed or rolled back, or when
** a btree handle is closed.
*/
struct BtLock {
Btree *pBtree; /* Btree handle holding this lock */
Pgno iTable; /* Root page of table */
u8 eLock; /* READ_LOCK or WRITE_LOCK */
BtLock *pNext; /* Next in BtShared.pLock list */
};
/* Candidate values for BtLock.eLock */
#define READ_LOCK 1
#define WRITE_LOCK 2
/* A Btree handle
**
** A database connection contains a pointer to an instance of
** this object for every database file that it has open. This structure
** is opaque to the database connection. The database connection cannot
** see the internals of this structure and only deals with pointers to
** this structure.
**
** For some database files, the same underlying database cache might be
** shared between multiple connections. In that case, each connection
** has it own instance of this object. But each instance of this object
** points to the same BtShared object. The database cache and the
** schema associated with the database file are all contained within
** the BtShared object.
**
** All fields in this structure are accessed under sqlite3.mutex.
** The pBt pointer itself may not be changed while there exists cursors
** in the referenced BtShared that point back to this Btree since those
** cursors have to go through this Btree to find their BtShared and
** they often do so without holding sqlite3.mutex.
*/
struct Btree {
sqlite3 *db; /* The database connection holding this btree */
BtShared *pBt; /* Sharable content of this btree */
u8 inTrans; /* TRANS_NONE, TRANS_READ or TRANS_WRITE */
u8 sharable; /* True if we can share pBt with another db */
u8 locked; /* True if db currently has pBt locked */
u8 hasIncrblobCur; /* True if there are one or more Incrblob cursors */
int wantToLock; /* Number of nested calls to sqlite3BtreeEnter() */
int nBackup; /* Number of backup operations reading this btree */
u32 iDataVersion; /* Combines with pBt->pPager->iDataVersion */
Btree *pNext; /* List of other sharable Btrees from the same db */
Btree *pPrev; /* Back pointer of the same list */
#ifndef SQLITE_OMIT_SHARED_CACHE
BtLock lock; /* Object used to lock page 1 */
#endif
};
/*
** Btree.inTrans may take one of the following values.
**
** If the shared-data extension is enabled, there may be multiple users
** of the Btree structure. At most one of these may open a write transaction,
** but any number may have active read transactions.
*/
#define TRANS_NONE 0
#define TRANS_READ 1
#define TRANS_WRITE 2
/*
** An instance of this object represents a single database file.
**
** A single database file can be in use at the same time by two
** or more database connections. When two or more connections are
** sharing the same database file, each connection has it own
** private Btree object for the file and each of those Btrees points
** to this one BtShared object. BtShared.nRef is the number of
** connections currently sharing this database file.
**
** Fields in this structure are accessed under the BtShared.mutex
** mutex, except for nRef and pNext which are accessed under the
** global SQLITE_MUTEX_STATIC_MASTER mutex. The pPager field
** may not be modified once it is initially set as long as nRef>0.
** The pSchema field may be set once under BtShared.mutex and
** thereafter is unchanged as long as nRef>0.
**
** isPending:
**
** If a BtShared client fails to obtain a write-lock on a database
** table (because there exists one or more read-locks on the table),
** the shared-cache enters 'pending-lock' state and isPending is
** set to true.
**
** The shared-cache leaves the 'pending lock' state when either of
** the following occur:
**
** 1) The current writer (BtShared.pWriter) concludes its transaction, OR
** 2) The number of locks held by other connections drops to zero.
**
** while in the 'pending-lock' state, no connection may start a new
** transaction.
**
** This feature is included to help prevent writer-starvation.
*/
struct BtShared {
Pager *pPager; /* The page cache */
sqlite3 *db; /* Database connection currently using this Btree */
#define ISAUTOVACUUM 0
#endif
/*
** This structure is passed around through all the sanity checking routines
** in order to keep track of some global state information.
**
** The aRef[] array is allocated so that there is 1 bit for each page in
** the database. As the integrity-check proceeds, for each page used in
** the database the corresponding bit is set. This allows integrity-check to
** detect pages that are used twice and orphaned pages (both of which
** indicate corruption).
*/
typedef struct IntegrityCk IntegrityCk;
struct IntegrityCk {
BtShared *pBt; /* The tree being checked out */
Pager *pPager; /* The associated pager. Also accessible by pBt->pPager */
u8 *aPgRef; /* 1 bit per page in the db (see above) */
Pgno nPage; /* Number of pages in the database */
int mxErr; /* Stop accumulating errors when this reaches zero */
int nErr; /* Number of messages written to zErrMsg so far */
int mallocFailed; /* A memory allocation error has occurred */
const char *zPfx; /* Error message prefix */
int v1, v2; /* Values for up to two %d fields in zPfx */
StrAccum errMsg; /* Accumulate the error message text here */
u32 *heap; /* Min-heap used for analyzing cell coverage */
};
/*
** Routines to read or write a two- and four-byte big-endian integer values.
*/
#define get2byte(x) ((x)[0]<<8 | (x)[1])
#define put2byte(p,v) ((p)[0] = (u8)((v)>>8), (p)[1] = (u8)(v))
#define get4byte sqlite3Get4byte
#define put4byte sqlite3Put4byte
/*
** get2byteAligned(), unlike get2byte(), requires that its argument point to a
** two-byte aligned address. get2bytea() is only used for accessing the
** cell addresses in a btree header.
*/
#if SQLITE_BYTEORDER==4321
# define get2byteAligned(x) (*(u16*)(x))
#elif SQLITE_BYTEORDER==1234 && GCC_VERSION>=4008000
# define get2byteAligned(x) __builtin_bswap16(*(u16*)(x))
#elif SQLITE_BYTEORDER==1234 && MSVC_VERSION>=1300
# define get2byteAligned(x) _byteswap_ushort(*(u16*)(x))
#else
# define get2byteAligned(x) ((x)[0]<<8 | (x)[1])
#endif
/************** End of btreeInt.h ********************************************/
/************** Continuing where we left off in btmutex.c ********************/
#ifndef SQLITE_OMIT_SHARED_CACHE
#if SQLITE_THREADSAFE
/*
** Obtain the BtShared mutex associated with B-Tree handle p. Also,
** set BtShared.db to the database handle associated with p and the
** p->locked boolean to true.
*/
static void lockBtreeMutex(Btree *p){
assert( p->locked==0 );
assert( sqlite3_mutex_notheld(p->pBt->mutex) );
assert( sqlite3_mutex_held(p->db->mutex) );
sqlite3_mutex_enter(p->pBt->mutex);
p->pBt->db = p->db;
p->locked = 1;
}
/*
** Release the BtShared mutex associated with B-Tree handle p and
** clear the p->locked boolean.
*/
static void SQLITE_NOINLINE unlockBtreeMutex(Btree *p){
BtShared *pBt = p->pBt;
assert( p->locked==1 );
assert( sqlite3_mutex_held(pBt->mutex) );
assert( sqlite3_mutex_held(p->db->mutex) );
assert( p->db==pBt->db );
sqlite3_mutex_leave(pBt->mutex);
p->locked = 0;
}
/* Forward reference */
static void SQLITE_NOINLINE btreeLockCarefully(Btree *p);
/*
** Enter a mutex on the given BTree object.
**
** If the object is not sharable, then no mutex is ever required
** and this routine is a no-op. The underlying mutex is non-recursive.
** But we keep a reference count in Btree.wantToLock so the behavior
** of this interface is recursive.
**
** To avoid deadlocks, multiple Btrees are locked in the same order
** by all database connections. The p->pNext is a list of other
** Btrees belonging to the same database connection as the p Btree
** which need to be locked after p. If we cannot get a lock on
** p, then first unlock all of the others on p->pNext, then wait
** for the lock to become available on p, then relock all of the
** subsequent Btrees that desire a lock.
*/
SQLITE_PRIVATE void sqlite3BtreeEnter(Btree *p){
/* Some basic sanity checking on the Btree. The list of Btrees
** connected by pNext and pPrev should be in sorted order by
** Btree.pBt value. All elements of the list should belong to
** the same connection. Only shared Btrees are on the list. */
assert( p->pNext==0 || p->pNext->pBt>p->pBt );
assert( p->pPrev==0 || p->pPrev->pBt<p->pBt );
assert( p->pNext==0 || p->pNext->db==p->db );
assert( p->pPrev==0 || p->pPrev->db==p->db );
assert( p->sharable || (p->pNext==0 && p->pPrev==0) );
/* Check for locking consistency */
assert( !p->locked || p->wantToLock>0 );
assert( p->sharable || p->wantToLock==0 );
/* We should already hold a lock on the database connection */
assert( sqlite3_mutex_held(p->db->mutex) );
/* Unless the database is sharable and unlocked, then BtShared.db
** should already be set correctly. */
assert( (p->locked==0 && p->sharable) || p->pBt->db==p->db );
if( !p->sharable ) return;
p->wantToLock++;
if( p->locked ) return;
btreeLockCarefully(p);
}
/* This is a helper function for sqlite3BtreeLock(). By moving
** complex, but seldom used logic, out of sqlite3BtreeLock() and
** into this routine, we avoid unnecessary stack pointer changes
** and thus help the sqlite3BtreeLock() routine to run much faster
** in the common case.
*/
static void SQLITE_NOINLINE btreeLockCarefully(Btree *p){
Btree *pLater;
/* In most cases, we should be able to acquire the lock we
** want without having to go through the ascending lock
** procedure that follows. Just be sure not to block.
*/
if( sqlite3_mutex_try(p->pBt->mutex)==SQLITE_OK ){
p->pBt->db = p->db;
p->locked = 1;
return;
}
/* To avoid deadlock, first release all locks with a larger
** BtShared address. Then acquire our lock. Then reacquire
** the other BtShared locks that we used to hold in ascending
** order.
*/
for(pLater=p->pNext; pLater; pLater=pLater->pNext){
assert( pLater->sharable );
assert( pLater->pNext==0 || pLater->pNext->pBt>pLater->pBt );
assert( !pLater->locked || pLater->wantToLock>0 );
if( pLater->locked ){
unlockBtreeMutex(pLater);
}
}
lockBtreeMutex(p);
for(pLater=p->pNext; pLater; pLater=pLater->pNext){
if( pLater->wantToLock ){
lockBtreeMutex(pLater);
}
}
}
/*
** Exit the recursive mutex on a Btree.
*/
SQLITE_PRIVATE void sqlite3BtreeLeave(Btree *p){
assert( sqlite3_mutex_held(p->db->mutex) );
if( p->sharable ){
assert( p->wantToLock>0 );
p->wantToLock--;
if( p->wantToLock==0 ){
unlockBtreeMutex(p);
}
}
}
#ifndef NDEBUG
/*
** Return true if the BtShared mutex is held on the btree, or if the
** B-Tree is not marked as sharable.
**
** This routine is used only from within assert() statements.
*/
SQLITE_PRIVATE int sqlite3BtreeHoldsMutex(Btree *p){
assert( p->sharable==0 || p->locked==0 || p->wantToLock>0 );
assert( p->sharable==0 || p->locked==0 || p->db==p->pBt->db );
assert( p->sharable==0 || p->locked==0 || sqlite3_mutex_held(p->pBt->mutex) );
assert( p->sharable==0 || p->locked==0 || sqlite3_mutex_held(p->db->mutex) );
return (p->sharable==0 || p->locked);
}
#endif
/*
** Enter the mutex on every Btree associated with a database
** connection. This is needed (for example) prior to parsing
** a statement since we will be comparing table and column names
** against all schemas and we do not want those schemas being
** reset out from under us.
**
** There is a corresponding leave-all procedures.
**
** Enter the mutexes in accending order by BtShared pointer address
** to avoid the possibility of deadlock when two threads with
** two or more btrees in common both try to lock all their btrees
** at the same instant.
*/
static void SQLITE_NOINLINE btreeEnterAll(sqlite3 *db){
int i;
int skipOk = 1;
Btree *p;
assert( sqlite3_mutex_held(db->mutex) );
for(i=0; i<db->nDb; i++){
p = db->aDb[i].pBt;
if( p && p->sharable ){
sqlite3BtreeEnter(p);
skipOk = 0;
}
}
db->noSharedCache = skipOk;
}
SQLITE_PRIVATE void sqlite3BtreeEnterAll(sqlite3 *db){
if( db->noSharedCache==0 ) btreeEnterAll(db);
}
static void SQLITE_NOINLINE btreeLeaveAll(sqlite3 *db){
int i;
Btree *p;
assert( sqlite3_mutex_held(db->mutex) );
for(i=0; i<db->nDb; i++){
p = db->aDb[i].pBt;
if( p ) sqlite3BtreeLeave(p);
}
}
SQLITE_PRIVATE void sqlite3BtreeLeaveAll(sqlite3 *db){
if( db->noSharedCache==0 ) btreeLeaveAll(db);
}
#ifndef NDEBUG
/*
** Return true if the current thread holds the database connection
** mutex and all required BtShared mutexes.
**
** This routine is used inside assert() statements only.
*/
SQLITE_PRIVATE int sqlite3BtreeHoldsAllMutexes(sqlite3 *db){
int i;
if( !sqlite3_mutex_held(db->mutex) ){
return 0;
}
for(i=0; i<db->nDb; i++){
Btree *p;
p = db->aDb[i].pBt;
if( p && p->sharable &&
(p->wantToLock==0 || !sqlite3_mutex_held(p->pBt->mutex)) ){
return 0;
}
}
return 1;
}
#endif /* NDEBUG */
#ifndef NDEBUG
/*
** Return true if the correct mutexes are held for accessing the
** db->aDb[iDb].pSchema structure. The mutexes required for schema
** access are:
**
** (1) The mutex on db
** (2) if iDb!=1, then the mutex on db->aDb[iDb].pBt.
**
** If pSchema is not NULL, then iDb is computed from pSchema and
** db using sqlite3SchemaToIndex().
*/
SQLITE_PRIVATE int sqlite3SchemaMutexHeld(sqlite3 *db, int iDb, Schema *pSchema){
Btree *p;
assert( db!=0 );
if( pSchema ) iDb = sqlite3SchemaToIndex(db, pSchema);
assert( iDb>=0 && iDb<db->nDb );
if( !sqlite3_mutex_held(db->mutex) ) return 0;
if( iDb==1 ) return 1;
p = db->aDb[iDb].pBt;
assert( p!=0 );
return p->sharable==0 || p->locked==1;
}
#endif /* NDEBUG */
#else /* SQLITE_THREADSAFE>0 above. SQLITE_THREADSAFE==0 below */
/*
** The following are special cases for mutex enter routines for use
** in single threaded applications that use shared cache. Except for
** these two routines, all mutex operations are no-ops in that case and
** are null #defines in btree.h.
**
** If shared cache is disabled, then all btree mutex routines, including
** the ones below, are no-ops and are null #defines in btree.h.
*/
SQLITE_PRIVATE void sqlite3BtreeEnter(Btree *p){
p->pBt->db = p->db;
}
SQLITE_PRIVATE void sqlite3BtreeEnterAll(sqlite3 *db){
int i;
for(i=0; i<db->nDb; i++){
Btree *p = db->aDb[i].pBt;
if( p ){
p->pBt->db = p->db;
}
}
}
#endif /* if SQLITE_THREADSAFE */
#ifndef SQLITE_OMIT_INCRBLOB
/*
** Enter a mutex on a Btree given a cursor owned by that Btree.
**
** These entry points are used by incremental I/O only. Enter() is required
** any time OMIT_SHARED_CACHE is not defined, regardless of whether or not
** the build is threadsafe. Leave() is only required by threadsafe builds.
*/
SQLITE_PRIVATE void sqlite3BtreeEnterCursor(BtCursor *pCur){
sqlite3BtreeEnter(pCur->pBtree);
}
# if SQLITE_THREADSAFE
SQLITE_PRIVATE void sqlite3BtreeLeaveCursor(BtCursor *pCur){
sqlite3BtreeLeave(pCur->pBtree);
}
# endif
#endif /* ifndef SQLITE_OMIT_INCRBLOB */
#endif /* ifndef SQLITE_OMIT_SHARED_CACHE */
/************** End of btmutex.c *********************************************/
/************** Begin file btree.c *******************************************/
/*
** 2004 April 6
**
** 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.
**
** Return true if it would be illegal for pBtree to write into the
** table or index rooted at iRoot because other shared connections are
** simultaneously reading that same table or index.
**
** It is illegal for pBtree to write if some other Btree object that
** shares the same BtShared object is currently reading or writing
** the iRoot table. Except, if the other Btree object has the
** read-uncommitted flag set, then it is OK for the other object to
** have a read cursor.
**
** For example, before writing to any part of the table or index
** rooted at page iRoot, one should call:
**
** assert( !hasReadConflicts(pBtree, iRoot) );
*/
static int hasReadConflicts(Btree *pBtree, Pgno iRoot){
BtCursor *p;
for(p=pBtree->pBt->pCursor; p; p=p->pNext){
if( p->pgnoRoot==iRoot
&& p->pBtree!=pBtree
&& 0==(p->pBtree->db->flags & SQLITE_ReadUncommit)
){
return 1;
}
}
return 0;
}
#endif /* #ifdef SQLITE_DEBUG */
/*
** Query to see if Btree handle p may obtain a lock of type eLock
** (READ_LOCK or WRITE_LOCK) on the table with root-page iTab. Return
** SQLITE_OK if the lock may be obtained (by calling
** setSharedCacheTableLock()), or SQLITE_LOCKED if not.
*/
static int querySharedCacheTableLock(Btree *p, Pgno iTab, u8 eLock){
BtShared *pBt = p->pBt;
BtLock *pIter;
assert( sqlite3BtreeHoldsMutex(p) );
assert( eLock==READ_LOCK || eLock==WRITE_LOCK );
assert( p->db!=0 );
assert( !(p->db->flags&SQLITE_ReadUncommit)||eLock==WRITE_LOCK||iTab==1 );
/* If requesting a write-lock, then the Btree must have an open write
** transaction on this file. And, obviously, for this to be so there
** must be an open write transaction on the file itself.
*/
assert( eLock==READ_LOCK || (p==pBt->pWriter && p->inTrans==TRANS_WRITE) );
assert( eLock==READ_LOCK || pBt->inTransaction==TRANS_WRITE );
/* This routine is a no-op if the shared-cache is not enabled */
if( !p->sharable ){
return SQLITE_OK;
}
/* If some other connection is holding an exclusive lock, the
** requested lock may not be obtained.
*/
if( pBt->pWriter!=p && (pBt->btsFlags & BTS_EXCLUSIVE)!=0 ){
sqlite3ConnectionBlocked(p->db, pBt->pWriter->db);
return SQLITE_LOCKED_SHAREDCACHE;
}
for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
/* The condition (pIter->eLock!=eLock) in the following if(...)
** statement is a simplification of:
**
** (eLock==WRITE_LOCK || pIter->eLock==WRITE_LOCK)
**
** since we know that if eLock==WRITE_LOCK, then no other connection
** may hold a WRITE_LOCK on any table in this file (since there can
** only be a single writer).
*/
assert( pIter->eLock==READ_LOCK || pIter->eLock==WRITE_LOCK );
assert( eLock==READ_LOCK || pIter->pBtree==p || pIter->eLock==READ_LOCK);
if( pIter->pBtree!=p && pIter->iTable==iTab && pIter->eLock!=eLock ){
sqlite3ConnectionBlocked(p->db, pIter->pBtree->db);
if( eLock==WRITE_LOCK ){
assert( p==pBt->pWriter );
pBt->btsFlags |= BTS_PENDING;
}
return SQLITE_LOCKED_SHAREDCACHE;
}
}
return SQLITE_OK;
}
#endif /* !SQLITE_OMIT_SHARED_CACHE */
#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** Add a lock on the table with root-page iTable to the shared-btree used
** by Btree handle p. Parameter eLock must be either READ_LOCK or
** WRITE_LOCK.
**
** This function assumes the following:
**
** (a) The specified Btree object p is connected to a sharable
** database (one with the BtShared.sharable flag set), and
**
** (b) No other Btree objects hold a lock that conflicts
** with the requested lock (i.e. querySharedCacheTableLock() has
** already been called and returned SQLITE_OK).
**
** SQLITE_OK is returned if the lock is added successfully. SQLITE_NOMEM
** is returned if a malloc attempt fails.
*/
static int setSharedCacheTableLock(Btree *p, Pgno iTable, u8 eLock){
BtShared *pBt = p->pBt;
BtLock *pLock = 0;
BtLock *pIter;
assert( sqlite3BtreeHoldsMutex(p) );
assert( eLock==READ_LOCK || eLock==WRITE_LOCK );
assert( p->db!=0 );
/* A connection with the read-uncommitted flag set will never try to
** obtain a read-lock using this function. The only read-lock obtained
** by a connection in read-uncommitted mode is on the sqlite_master
** table, and that lock is obtained in BtreeBeginTrans(). */
assert( 0==(p->db->flags&SQLITE_ReadUncommit) || eLock==WRITE_LOCK );
/* This function should only be called on a sharable b-tree after it
** has been determined that no other b-tree holds a conflicting lock. */
assert( p->sharable );
assert( SQLITE_OK==querySharedCacheTableLock(p, iTable, eLock) );
/* First search the list for an existing lock on this table. */
for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
if( pIter->iTable==iTable && pIter->pBtree==p ){
pLock = pIter;
break;
}
}
/* If the above search did not find a BtLock struct associating Btree p
** with table iTable, allocate one and link it into the list.
*/
** by the various routines that manipulate binary cells. Which
** can mean that fillInCell() only initializes the first 2 or 3
** bytes of pTmpSpace, but that the first 4 bytes are copied from
** it into a database page. This is not actually a problem, but it
** does cause a valgrind error when the 1 or 2 bytes of unitialized
** data is passed to system call write(). So to avoid this error,
** zero the first 4 bytes of temp space here.
**
** Also: Provide four bytes of initialized space before the
** beginning of pTmpSpace as an area available to prepend the
** left-child pointer to the beginning of a cell.
*/
if( pBt->pTmpSpace ){
memset(pBt->pTmpSpace, 0, 8);
pBt->pTmpSpace += 4;
}
}
}
/*
** Free the pBt->pTmpSpace allocation
*/
static void freeTempSpace(BtShared *pBt){
if( pBt->pTmpSpace ){
pBt->pTmpSpace -= 4;
sqlite3PageFree(pBt->pTmpSpace);
pBt->pTmpSpace = 0;
}
}
/*
** Close an open database and invalidate all cursors.
*/
SQLITE_PRIVATE int sqlite3BtreeClose(Btree *p){
BtShared *pBt = p->pBt;
BtCursor *pCur;
/* Close all cursors opened via this handle. */
assert( sqlite3_mutex_held(p->db->mutex) );
sqlite3BtreeEnter(p);
pCur = pBt->pCursor;
while( pCur ){
BtCursor *pTmp = pCur;
pCur = pCur->pNext;
if( pTmp->pBtree==p ){
sqlite3BtreeCloseCursor(pTmp);
}
}
/* Rollback any active transaction and free the handle structure.
** The call to sqlite3BtreeRollback() drops any table-locks held by
** this handle.
*/
sqlite3BtreeRollback(p, SQLITE_OK, 0);
sqlite3BtreeLeave(p);
/* If there are still other outstanding references to the shared-btree
** structure, return now. The remainder of this procedure cleans
** up the shared-btree.
*/
assert( p->wantToLock==0 && p->locked==0 );
if( !p->sharable || removeFromSharingList(pBt) ){
/* The pBt is no longer on the sharing list, so we can access
** it without having to hold the mutex.
**
** Clean out and delete the BtShared object.
*/
assert( !pBt->pCursor );
sqlite3PagerClose(pBt->pPager, p->db);
if( pBt->xFreeSchema && pBt->pSchema ){
pBt->xFreeSchema(pBt->pSchema);
}
sqlite3DbFree(0, pBt->pSchema);
freeTempSpace(pBt);
sqlite3_free(pBt);
}
#ifndef SQLITE_OMIT_SHARED_CACHE
assert( p->wantToLock==0 );
assert( p->locked==0 );
if( p->pPrev ) p->pPrev->pNext = p->pNext;
if( p->pNext ) p->pNext->pPrev = p->pPrev;
#endif
sqlite3_free(p);
return SQLITE_OK;
}
/*
** Change the "soft" limit on the number of pages in the cache.
** Unused and unmodified pages will be recycled when the number of
** pages in the cache exceeds this soft limit. But the size of the
** cache is allowed to grow larger than this limit if it contains
** dirty pages or pages still in active use.
*/
SQLITE_PRIVATE int sqlite3BtreeSetCacheSize(Btree *p, int mxPage){
BtShared *pBt = p->pBt;
assert( sqlite3_mutex_held(p->db->mutex) );
sqlite3BtreeEnter(p);
sqlite3PagerSetCachesize(pBt->pPager, mxPage);
sqlite3BtreeLeave(p);
return SQLITE_OK;
}
/*
** Change the "spill" limit on the number of pages in the cache.
** If the number of pages exceeds this limit during a write transaction,
** the pager might attempt to "spill" pages to the journal early in
** order to free up memory.
**
** The value returned is the current spill size. If zero is passed
** as an argument, no changes are made to the spill size setting, so
** using mxPage of 0 is a way to query the current spill size.
*/
SQLITE_PRIVATE int sqlite3BtreeSetSpillSize(Btree *p, int mxPage){
BtShared *pBt = p->pBt;
int res;
assert( sqlite3_mutex_held(p->db->mutex) );
sqlite3BtreeEnter(p);
res = sqlite3PagerSetSpillsize(pBt->pPager, mxPage);
sqlite3BtreeLeave(p);
return res;
}
#if SQLITE_MAX_MMAP_SIZE>0
/*
** Change the limit on the amount of the database file that may be
** memory mapped.
*/
SQLITE_PRIVATE int sqlite3BtreeSetMmapLimit(Btree *p, sqlite3_int64 szMmap){
BtShared *pBt = p->pBt;
assert( sqlite3_mutex_held(p->db->mutex) );
sqlite3BtreeEnter(p);
sqlite3PagerSetMmapLimit(pBt->pPager, szMmap);
sqlite3BtreeLeave(p);
return SQLITE_OK;
}
#endif /* SQLITE_MAX_MMAP_SIZE>0 */
/*
#endif
}
/*
** Return the value of the 'auto-vacuum' property. If auto-vacuum is
** enabled 1 is returned. Otherwise 0.
*/
SQLITE_PRIVATE int sqlite3BtreeGetAutoVacuum(Btree *p){
#ifdef SQLITE_OMIT_AUTOVACUUM
return BTREE_AUTOVACUUM_NONE;
#else
int rc;
sqlite3BtreeEnter(p);
rc = (
(!p->pBt->autoVacuum)?BTREE_AUTOVACUUM_NONE:
(!p->pBt->incrVacuum)?BTREE_AUTOVACUUM_FULL:
BTREE_AUTOVACUUM_INCR
);
sqlite3BtreeLeave(p);
return rc;
#endif
}
/*
** If the user has not set the safety-level for this database connection
** using "PRAGMA synchronous", and if the safety-level is not already
** set to the value passed to this function as the second parameter,
** set it so.
*/
#if SQLITE_DEFAULT_SYNCHRONOUS!=SQLITE_DEFAULT_WAL_SYNCHRONOUS \
&& !defined(SQLITE_OMIT_WAL)
static void setDefaultSyncFlag(BtShared *pBt, u8 safety_level){
sqlite3 *db;
Db *pDb;
if( (db=pBt->db)!=0 && (pDb=db->aDb)!=0 ){
while( pDb->pBt==0 || pDb->pBt->pBt!=pBt ){ pDb++; }
if( pDb->bSyncSet==0
&& pDb->safety_level!=safety_level
&& pDb!=&db->aDb[1]
){
pDb->safety_level = safety_level;
sqlite3PagerSetFlags(pBt->pPager,
pDb->safety_level | (db->flags & PAGER_FLAGS_MASK));
}
}
}
#else
# define setDefaultSyncFlag(pBt,safety_level)
#endif
/* Forward declaration */
static int newDatabase(BtShared*);
/*
** Get a reference to pPage1 of the database file. This will
** also acquire a readlock on that file.
**
** SQLITE_OK is returned on success. If the file is not a
** well-formed database file, then SQLITE_CORRUPT is returned.
** SQLITE_BUSY is returned if the database is locked. SQLITE_NOMEM
** is returned if we run out of memory.
*/
static int lockBtree(BtShared *pBt){
int rc; /* Result code from subfunctions */
MemPage *pPage1; /* Page 1 of the database file */
int nPage; /* Number of pages in the database */
int nPageFile = 0; /* Number of pages in the database file */
int nPageHeader; /* Number of pages in the database according to hdr */
assert( sqlite3_mutex_held(pBt->mutex) );
assert( pBt->pPage1==0 );
rc = sqlite3PagerSharedLock(pBt->pPager);
if( rc!=SQLITE_OK ) return rc;
rc = btreeGetPage(pBt, 1, &pPage1, 0);
if( rc!=SQLITE_OK ) return rc;
/* Do some checking to help insure the file we opened really is
** a valid database file.
*/
nPage = nPageHeader = get4byte(28+(u8*)pPage1->aData);
sqlite3PagerPagecount(pBt->pPager, &nPageFile);
if( nPage==0 || memcmp(24+(u8*)pPage1->aData, 92+(u8*)pPage1->aData,4)!=0 ){
nPage = nPageFile;
}
if( (pBt->db->flags & SQLITE_ResetDatabase)!=0 ){
nPage = 0;
}
if( nPage>0 ){
u32 pageSize;
u32 usableSize;
u8 *page1 = pPage1->aData;
rc = SQLITE_NOTADB;
/* EVIDENCE-OF: R-43737-39999 Every valid SQLite database file begins
** with the following 16 bytes (in hex): 53 51 4c 69 74 65 20 66 6f 72 6d
** 61 74 20 33 00. */
if( memcmp(page1, zMagicHeader, 16)!=0 ){
goto page1_init_failed;
}
#ifdef SQLITE_OMIT_WAL
if( page1[18]>1 ){
pBt->btsFlags |= BTS_READ_ONLY;
}
if( page1[19]>1 ){
goto page1_init_failed;
}
#else
if( page1[18]>2 ){
pBt->btsFlags |= BTS_READ_ONLY;
}
if( page1[19]>2 ){
goto page1_init_failed;
}
/* If the write version is set to 2, this database should be accessed
** in WAL mode. If the log is not already open, open it now. Then
** return SQLITE_OK and return without populating BtShared.pPage1.
** The caller detects this and calls this function again. This is
** required as the version of page 1 currently in the page1 buffer
** may not be the latest version - there may be a newer one in the log
assert( sizeof(zMagicHeader)==16 );
data[16] = (u8)((pBt->pageSize>>8)&0xff);
data[17] = (u8)((pBt->pageSize>>16)&0xff);
data[18] = 1;
data[19] = 1;
assert( pBt->usableSize<=pBt->pageSize && pBt->usableSize+255>=pBt->pageSize);
data[20] = (u8)(pBt->pageSize - pBt->usableSize);
data[21] = 64;
data[22] = 32;
data[23] = 32;
memset(&data[24], 0, 100-24);
zeroPage(pP1, PTF_INTKEY|PTF_LEAF|PTF_LEAFDATA );
pBt->btsFlags |= BTS_PAGESIZE_FIXED;
#ifndef SQLITE_OMIT_AUTOVACUUM
assert( pBt->autoVacuum==1 || pBt->autoVacuum==0 );
assert( pBt->incrVacuum==1 || pBt->incrVacuum==0 );
put4byte(&data[36 + 4*4], pBt->autoVacuum);
put4byte(&data[36 + 7*4], pBt->incrVacuum);
#endif
pBt->nPage = 1;
data[31] = 1;
return SQLITE_OK;
}
/*
** Initialize the first page of the database file (creating a database
** consisting of a single page and no schema objects). Return SQLITE_OK
** if successful, or an SQLite error code otherwise.
*/
SQLITE_PRIVATE int sqlite3BtreeNewDb(Btree *p){
int rc;
sqlite3BtreeEnter(p);
p->pBt->nPage = 0;
rc = newDatabase(p->pBt);
sqlite3BtreeLeave(p);
return rc;
}
/*
** Attempt to start a new transaction. A write-transaction
** is started if the second argument is nonzero, otherwise a read-
** transaction. If the second argument is 2 or more and exclusive
** transaction is started, meaning that no other process is allowed
** to access the database. A preexisting transaction may not be
** upgraded to exclusive by calling this routine a second time - the
** exclusivity flag only works for a new transaction.
**
** A write-transaction must be started before attempting any
** changes to the database. None of the following routines
** will work unless a transaction is started first:
**
** sqlite3BtreeCreateTable()
** sqlite3BtreeCreateIndex()
** sqlite3BtreeClearTable()
** sqlite3BtreeDropTable()
** sqlite3BtreeInsert()
** sqlite3BtreeDelete()
** sqlite3BtreeUpdateMeta()
**
** If an initial attempt to acquire the lock fails because of lock contention
** and the database was previously unlocked, then invoke the busy handler
** if there is one. But if there was previously a read-lock, do not
** invoke the busy handler - just return SQLITE_BUSY. SQLITE_BUSY is
** returned when there is already a read-lock in order to avoid a deadlock.
**
** Suppose there are two processes A and B. A has a read lock and B has
** a reserved lock. B tries to promote to exclusive but is blocked because
** of A's read lock. A tries to promote to reserved but is blocked by B.
** One or the other of the two processes must give way or there can be
** no progress. By returning SQLITE_BUSY and not invoking the busy callback
** when A already has a read lock, we encourage A to give up and let B
** proceed.
*/
SQLITE_PRIVATE int sqlite3BtreeBeginTrans(Btree *p, int wrflag, int *pSchemaVersion){
BtShared *pBt = p->pBt;
int rc = SQLITE_OK;
sqlite3BtreeEnter(p);
btreeIntegrity(p);
/* If the btree is already in a write-transaction, or it
** is already in a read-transaction and a read-transaction
** is requested, this is a no-op.
*/
if( p->inTrans==TRANS_WRITE || (p->inTrans==TRANS_READ && !wrflag) ){
goto trans_begun;
}
assert( pBt->inTransaction==TRANS_WRITE || IfNotOmitAV(pBt->bDoTruncate)==0 );
if( (p->db->flags & SQLITE_ResetDatabase)
&& sqlite3PagerIsreadonly(pBt->pPager)==0
){
pBt->btsFlags &= ~BTS_READ_ONLY;
}
/* Write transactions are not possible on a read-only database */
if( (pBt->btsFlags & BTS_READ_ONLY)!=0 && wrflag ){
rc = SQLITE_READONLY;
goto trans_begun;
}
#ifndef SQLITE_OMIT_SHARED_CACHE
{
sqlite3 *pBlock = 0;
/* If another database handle has already opened a write transaction
** on this shared-btree structure and a second write transaction is
** requested, return SQLITE_LOCKED.
*/
if( (wrflag && pBt->inTransaction==TRANS_WRITE)
|| (pBt->btsFlags & BTS_PENDING)!=0
){
pBlock = pBt->pWriter->db;
}else if( wrflag>1 ){
BtLock *pIter;
for(pIter=pBt->pLock; pIter; pIter=pIter->pNext){
if( pIter->pBtree!=p ){
pBlock = pIter->pBtree->db;
break;
}
}
}
if( pBlock ){
sqlite3ConnectionBlocked(p->db, pBlock);
rc = SQLITE_LOCKED_SHAREDCACHE;
goto trans_begun;
}
}
#endif
/* Any read-only or read-write transaction implies a read-lock on
** page 1. So if some other shared-cache client already has a write-lock
** on page 1, the transaction cannot be opened. */
rc = querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK);
if( SQLITE_OK!=rc ) goto trans_begun;
pBt->btsFlags &= ~BTS_INITIALLY_EMPTY;
if( pBt->nPage==0 ) pBt->btsFlags |= BTS_INITIALLY_EMPTY;
do {
/* Call lockBtree() until either pBt->pPage1 is populated or
** lockBtree() returns something other than SQLITE_OK. lockBtree()
** may return SQLITE_OK but leave pBt->pPage1 set to 0 if after
** reading page 1 it discovers that the page-size of the database
** file is not pBt->pageSize. In this case lockBtree() will update
** pBt->pageSize to the page-size of the file on disk.
*/
while( pBt->pPage1==0 && SQLITE_OK==(rc = lockBtree(pBt)) );
if( rc==SQLITE_OK && wrflag ){
if( (pBt->btsFlags & BTS_READ_ONLY)!=0 ){
rc = SQLITE_READONLY;
}else{
rc = sqlite3PagerBegin(pBt->pPager,wrflag>1,sqlite3TempInMemory(p->db));
if( rc==SQLITE_OK ){
rc = newDatabase(pBt);
}else if( rc==SQLITE_BUSY_SNAPSHOT && pBt->inTransaction==TRANS_NONE ){
/* if there was no transaction opened when this function was
** called and SQLITE_BUSY_SNAPSHOT is returned, change the error
** code to SQLITE_BUSY. */
rc = SQLITE_BUSY;
}
}
}
if( rc!=SQLITE_OK ){
unlockBtreeIfUnused(pBt);
}
}while( (rc&0xFF)==SQLITE_BUSY && pBt->inTransaction==TRANS_NONE &&
btreeInvokeBusyHandler(pBt) );
sqlite3PagerResetLockTimeout(pBt->pPager);
if( rc==SQLITE_OK ){
if( p->inTrans==TRANS_NONE ){
pBt->nTransaction++;
#ifndef SQLITE_OMIT_SHARED_CACHE
if( p->sharable ){
assert( p->lock.pBtree==p && p->lock.iTable==1 );
p->lock.eLock = READ_LOCK;
p->lock.pNext = pBt->pLock;
pBt->pLock = &p->lock;
}
#endif
}
p->inTrans = (wrflag?TRANS_WRITE:TRANS_READ);
return 0;
}
}
if( i<0 ){
sqlite3ErrorWithMsg(pErrorDb, SQLITE_ERROR, "unknown database %s", zDb);
return 0;
}
return pDb->aDb[i].pBt;
}
/*
** Attempt to set the page size of the destination to match the page size
** of the source.
*/
static int setDestPgsz(sqlite3_backup *p){
int rc;
rc = sqlite3BtreeSetPageSize(p->pDest,sqlite3BtreeGetPageSize(p->pSrc),-1,0);
return rc;
}
/*
** Check that there is no open read-transaction on the b-tree passed as the
** second argument. If there is not, return SQLITE_OK. Otherwise, if there
** is an open read-transaction, return SQLITE_ERROR and leave an error
** message in database handle db.
*/
static int checkReadTransaction(sqlite3 *db, Btree *p){
if( sqlite3BtreeIsInReadTrans(p) ){
sqlite3ErrorWithMsg(db, SQLITE_ERROR, "destination database is in use");
return SQLITE_ERROR;
}
return SQLITE_OK;
}
/*
** Create an sqlite3_backup process to copy the contents of zSrcDb from
** connection handle pSrcDb to zDestDb in pDestDb. If successful, return
** a pointer to the new sqlite3_backup object.
**
** If an error occurs, NULL is returned and an error code and error message
** stored in database handle pDestDb.
*/
SQLITE_API sqlite3_backup *sqlite3_backup_init(
sqlite3* pDestDb, /* Database to write to */
const char *zDestDb, /* Name of database within pDestDb */
sqlite3* pSrcDb, /* Database connection to read from */
const char *zSrcDb /* Name of database within pSrcDb */
){
sqlite3_backup *p; /* Value to return */
#ifdef SQLITE_ENABLE_API_ARMOR
if( !sqlite3SafetyCheckOk(pSrcDb)||!sqlite3SafetyCheckOk(pDestDb) ){
(void)SQLITE_MISUSE_BKPT;
return 0;
}
#endif
/* Lock the source database handle. The destination database
** handle is not locked in this routine, but it is locked in
** sqlite3_backup_step(). The user is required to ensure that no
** other thread accesses the destination handle for the duration
** of the backup operation. Any attempt to use the destination
** database connection while a backup is in progress may cause
** a malfunction or a deadlock.
*/
sqlite3_mutex_enter(pSrcDb->mutex);
sqlite3_mutex_enter(pDestDb->mutex);
if( pSrcDb==pDestDb ){
sqlite3ErrorWithMsg(
pDestDb, SQLITE_ERROR, "source and destination must be distinct"
);
p = 0;
}else {
/* Allocate space for a new sqlite3_backup object...
** EVIDENCE-OF: R-64852-21591 The sqlite3_backup object is created by a
** call to sqlite3_backup_init() and is destroyed by a call to
** sqlite3_backup_finish(). */
p = (sqlite3_backup *)sqlite3MallocZero(sizeof(sqlite3_backup));
if( !p ){
sqlite3Error(pDestDb, SQLITE_NOMEM_BKPT);
}
}
/* If the allocation succeeded, populate the new object. */
if( p ){
p->pSrc = findBtree(pDestDb, pSrcDb, zSrcDb);
p->pDest = findBtree(pDestDb, pDestDb, zDestDb);
p->pDestDb = pDestDb;
p->pSrcDb = pSrcDb;
p->iNext = 1;
p->isAttached = 0;
if( 0==p->pSrc || 0==p->pDest
|| checkReadTransaction(pDestDb, p->pDest)!=SQLITE_OK
){
/* One (or both) of the named databases did not exist or an OOM
** error was hit. Or there is a transaction open on the destination
** database. The error has already been written into the pDestDb
** handle. All that is left to do here is free the sqlite3_backup
** structure. */
sqlite3_free(p);
p = 0;
}
}
if( p ){
p->pSrc->nBackup++;
}
sqlite3_mutex_leave(pDestDb->mutex);
sqlite3_mutex_leave(pSrcDb->mutex);
return p;
}
/*
** Argument rc is an SQLite error code. Return true if this error is
** considered fatal if encountered during a backup operation. All errors
** are considered fatal except for SQLITE_BUSY and SQLITE_LOCKED.
*/
return rc;
}
/*
** Register this backup object with the associated source pager for
** callbacks when pages are changed or the cache invalidated.
*/
static void attachBackupObject(sqlite3_backup *p){
sqlite3_backup **pp;
assert( sqlite3BtreeHoldsMutex(p->pSrc) );
pp = sqlite3PagerBackupPtr(sqlite3BtreePager(p->pSrc));
p->pNext = *pp;
*pp = p;
p->isAttached = 1;
}
/*
** Copy nPage pages from the source b-tree to the destination.
*/
SQLITE_API int sqlite3_backup_step(sqlite3_backup *p, int nPage){
int rc;
int destMode; /* Destination journal mode */
int pgszSrc = 0; /* Source page size */
int pgszDest = 0; /* Destination page size */
#ifdef SQLITE_ENABLE_API_ARMOR
if( p==0 ) return SQLITE_MISUSE_BKPT;
#endif
sqlite3_mutex_enter(p->pSrcDb->mutex);
sqlite3BtreeEnter(p->pSrc);
if( p->pDestDb ){
sqlite3_mutex_enter(p->pDestDb->mutex);
}
rc = p->rc;
if( !isFatalError(rc) ){
Pager * const pSrcPager = sqlite3BtreePager(p->pSrc); /* Source pager */
Pager * const pDestPager = sqlite3BtreePager(p->pDest); /* Dest pager */
int ii; /* Iterator variable */
int nSrcPage = -1; /* Size of source db in pages */
int bCloseTrans = 0; /* True if src db requires unlocking */
/* If the source pager is currently in a write-transaction, return
** SQLITE_BUSY immediately.
*/
if( p->pDestDb && p->pSrc->pBt->inTransaction==TRANS_WRITE ){
rc = SQLITE_BUSY;
}else{
rc = SQLITE_OK;
}
/* If there is no open read-transaction on the source database, open
** one now. If a transaction is opened here, then it will be closed
** before this function exits.
*/
if( rc==SQLITE_OK && 0==sqlite3BtreeIsInReadTrans(p->pSrc) ){
rc = sqlite3BtreeBeginTrans(p->pSrc, 0, 0);
bCloseTrans = 1;
}
/* If the destination database has not yet been locked (i.e. if this
** is the first call to backup_step() for the current backup operation),
** try to set its page size to the same as the source database. This
** is especially important on ZipVFS systems, as in that case it is
** not possible to create a database file that uses one page size by
** writing to it with another. */
if( p->bDestLocked==0 && rc==SQLITE_OK && setDestPgsz(p)==SQLITE_NOMEM ){
rc = SQLITE_NOMEM;
}
/* Lock the destination database, if it is not locked already. */
if( SQLITE_OK==rc && p->bDestLocked==0
&& SQLITE_OK==(rc = sqlite3BtreeBeginTrans(p->pDest, 2,
(int*)&p->iDestSchema))
){
p->bDestLocked = 1;
}
/* Do not allow backup if the destination database is in WAL mode
** and the page sizes are different between source and destination */
pgszSrc = sqlite3BtreeGetPageSize(p->pSrc);
pgszDest = sqlite3BtreeGetPageSize(p->pDest);
destMode = sqlite3PagerGetJournalMode(sqlite3BtreePager(p->pDest));
if( SQLITE_OK==rc && destMode==PAGER_JOURNALMODE_WAL && pgszSrc!=pgszDest ){
rc = SQLITE_READONLY;
}
/* Now that there is a read-lock on the source database, query the
** source pager for the number of pages in the database.
*/
nSrcPage = (int)sqlite3BtreeLastPage(p->pSrc);
assert( nSrcPage>=0 );
for(ii=0; (nPage<0 || ii<nPage) && p->iNext<=(Pgno)nSrcPage && !rc; ii++){
const Pgno iSrcPg = p->iNext; /* Source page number */
if( iSrcPg!=PENDING_BYTE_PAGE(p->pSrc->pBt) ){
DbPage *pSrcPg; /* Source page object */
rc = sqlite3PagerGet(pSrcPager, iSrcPg, &pSrcPg,PAGER_GET_READONLY);
if( rc==SQLITE_OK ){
rc = backupOnePage(p, iSrcPg, sqlite3PagerGetData(pSrcPg), 0);
sqlite3PagerUnref(pSrcPg);
}
}
p->iNext++;
}
if( rc==SQLITE_OK ){
p->nPagecount = nSrcPage;
p->nRemaining = nSrcPage+1-p->iNext;
if( p->iNext>(Pgno)nSrcPage ){
rc = SQLITE_DONE;
}else if( !p->isAttached ){
attachBackupObject(p);
}
}
/* Update the schema version field in the destination database. This
** is to make sure that the schema-version really does change in
** the case where the source and destination databases have the
** same schema version.
*/
if( rc==SQLITE_DONE ){
if( nSrcPage==0 ){
rc = sqlite3BtreeNewDb(p->pDest);
nSrcPage = 1;
}
if( rc==SQLITE_OK || rc==SQLITE_DONE ){
rc = sqlite3BtreeUpdateMeta(p->pDest,1,p->iDestSchema+1);
}
if( rc==SQLITE_OK ){
if( p->pDestDb ){
sqlite3ResetAllSchemasOfConnection(p->pDestDb);
}
#endif /* VDBE_DISPLAY_P4 */
/*
** Declare to the Vdbe that the BTree object at db->aDb[i] is used.
**
** The prepared statements need to know in advance the complete set of
** attached databases that will be use. A mask of these databases
** is maintained in p->btreeMask. The p->lockMask value is the subset of
** p->btreeMask of databases that will require a lock.
*/
SQLITE_PRIVATE void sqlite3VdbeUsesBtree(Vdbe *p, int i){
assert( i>=0 && i<p->db->nDb && i<(int)sizeof(yDbMask)*8 );
assert( i<(int)sizeof(p->btreeMask)*8 );
DbMaskSet(p->btreeMask, i);
if( i!=1 && sqlite3BtreeSharable(p->db->aDb[i].pBt) ){
DbMaskSet(p->lockMask, i);
}
}
#if !defined(SQLITE_OMIT_SHARED_CACHE)
/*
** If SQLite is compiled to support shared-cache mode and to be threadsafe,
** this routine obtains the mutex associated with each BtShared structure
** that may be accessed by the VM passed as an argument. In doing so it also
** sets the BtShared.db member of each of the BtShared structures, ensuring
** that the correct busy-handler callback is invoked if required.
**
** If SQLite is not threadsafe but does support shared-cache mode, then
** sqlite3BtreeEnter() is invoked to set the BtShared.db variables
** of all of BtShared structures accessible via the database handle
** associated with the VM.
**
** If SQLite is not threadsafe and does not support shared-cache mode, this
** function is a no-op.
**
** The p->btreeMask field is a bitmask of all btrees that the prepared
** statement p will ever use. Let N be the number of bits in p->btreeMask
** corresponding to btrees that use shared cache. Then the runtime of
** this routine is N*N. But as N is rarely more than 1, this should not
** be a problem.
*/
SQLITE_PRIVATE void sqlite3VdbeEnter(Vdbe *p){
int i;
sqlite3 *db;
Db *aDb;
int nDb;
if( DbMaskAllZero(p->lockMask) ) return; /* The common case */
db = p->db;
aDb = db->aDb;
nDb = db->nDb;
for(i=0; i<nDb; i++){
if( i!=1 && DbMaskTest(p->lockMask,i) && ALWAYS(aDb[i].pBt!=0) ){
sqlite3BtreeEnter(aDb[i].pBt);
}
}
}
#endif
#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
/*
** Unlock all of the btrees previously locked by a call to sqlite3VdbeEnter().
*/
static SQLITE_NOINLINE void vdbeLeave(Vdbe *p){
int i;
sqlite3 *db;
Db *aDb;
int nDb;
db = p->db;
aDb = db->aDb;
nDb = db->nDb;
for(i=0; i<nDb; i++){
if( i!=1 && DbMaskTest(p->lockMask,i) && ALWAYS(aDb[i].pBt!=0) ){
sqlite3BtreeLeave(aDb[i].pBt);
}
}
}
SQLITE_PRIVATE void sqlite3VdbeLeave(Vdbe *p){
if( DbMaskAllZero(p->lockMask) ) return; /* The common case */
vdbeLeave(p);
}
#endif
#if defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
/*
** Print a single opcode. This routine is used for debugging only.
*/
SQLITE_PRIVATE void sqlite3VdbePrintOp(FILE *pOut, int pc, VdbeOp *pOp){
char *zP4;
char zPtr[50];
char zCom[100];
static const char *zFormat1 = "%4d %-13s %4d %4d %4d %-13s %.2X %s\n";
if( pOut==0 ) pOut = stdout;
zP4 = displayP4(pOp, zPtr, sizeof(zPtr));
#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
displayComment(pOp, zP4, zCom, sizeof(zCom));
#else
zCom[0] = 0;
#endif
/* NB: The sqlite3OpcodeName() function is implemented by code created
** by the mkopcodeh.awk and mkopcodec.awk scripts which extract the
** information from the vdbe.c source text */
fprintf(pOut, zFormat1, pc,
sqlite3OpcodeName(pOp->opcode), pOp->p1, pOp->p2, pOp->p3, zP4, pOp->p5,
zCom
);
fflush(pOut);
}
#endif
/*
** Initialize an array of N Mem element.
*/
static void initMemArray(Mem *p, int N, sqlite3 *db, u16 flags){
while( (N--)>0 ){
p->db = db;
p->flags = flags;
p->szMalloc = 0;
#ifdef SQLITE_DEBUG
p->pScopyFrom = 0;
#endif
p++;
sqlite3RollbackAll(db, SQLITE_ABORT_ROLLBACK);
sqlite3CloseSavepoints(db);
db->autoCommit = 1;
p->nChange = 0;
}
}
/* If eStatementOp is non-zero, then a statement transaction needs to
** be committed or rolled back. Call sqlite3VdbeCloseStatement() to
** do so. If this operation returns an error, and the current statement
** error code is SQLITE_OK or SQLITE_CONSTRAINT, then promote the
** current statement error code.
*/
if( eStatementOp ){
rc = sqlite3VdbeCloseStatement(p, eStatementOp);
if( rc ){
if( p->rc==SQLITE_OK || (p->rc&0xff)==SQLITE_CONSTRAINT ){
p->rc = rc;
sqlite3DbFree(db, p->zErrMsg);
p->zErrMsg = 0;
}
sqlite3RollbackAll(db, SQLITE_ABORT_ROLLBACK);
sqlite3CloseSavepoints(db);
db->autoCommit = 1;
p->nChange = 0;
}
}
/* If this was an INSERT, UPDATE or DELETE and no statement transaction
** has been rolled back, update the database connection change-counter.
*/
if( p->changeCntOn ){
if( eStatementOp!=SAVEPOINT_ROLLBACK ){
sqlite3VdbeSetChanges(db, p->nChange);
}else{
sqlite3VdbeSetChanges(db, 0);
}
p->nChange = 0;
}
/* Release the locks */
sqlite3VdbeLeave(p);
}
/* We have successfully halted and closed the VM. Record this fact. */
if( p->pc>=0 ){
db->nVdbeActive--;
if( !p->readOnly ) db->nVdbeWrite--;
if( p->bIsReader ) db->nVdbeRead--;
assert( db->nVdbeActive>=db->nVdbeRead );
assert( db->nVdbeRead>=db->nVdbeWrite );
assert( db->nVdbeWrite>=0 );
}
p->magic = VDBE_MAGIC_HALT;
checkActiveVdbeCnt(db);
if( db->mallocFailed ){
p->rc = SQLITE_NOMEM_BKPT;
}
/* If the auto-commit flag is set to true, then any locks that were held
** by connection db have now been released. Call sqlite3ConnectionUnlocked()
** to invoke any required unlock-notify callbacks.
*/
if( db->autoCommit ){
sqlite3ConnectionUnlocked(db);
}
assert( db->nVdbeActive>0 || db->autoCommit==0 || db->nStatement==0 );
return (p->rc==SQLITE_BUSY ? SQLITE_BUSY : SQLITE_OK);
}
/*
** Each VDBE holds the result of the most recent sqlite3_step() call
** in p->rc. This routine sets that result back to SQLITE_OK.
*/
SQLITE_PRIVATE void sqlite3VdbeResetStepResult(Vdbe *p){
p->rc = SQLITE_OK;
}
/*
** Copy the error code and error message belonging to the VDBE passed
** as the first argument to its database handle (so that they will be
** returned by calls to sqlite3_errcode() and sqlite3_errmsg()).
**
** This function does not clear the VDBE error code or message, just
** copies them to the database handle.
*/
SQLITE_PRIVATE int sqlite3VdbeTransferError(Vdbe *p){
sqlite3 *db = p->db;
int rc = p->rc;
if( p->zErrMsg ){
db->bBenignMalloc++;
sqlite3BeginBenignMalloc();
if( db->pErr==0 ) db->pErr = sqlite3ValueNew(db);
sqlite3ValueSetStr(db->pErr, -1, p->zErrMsg, SQLITE_UTF8, SQLITE_TRANSIENT);
sqlite3EndBenignMalloc();
db->bBenignMalloc--;
}else if( db->pErr ){
sqlite3ValueSetNull(db->pErr);
}
db->errCode = rc;
return rc;
}
#ifdef SQLITE_ENABLE_SQLLOG
/*
** If an SQLITE_CONFIG_SQLLOG hook is registered and the VM has been run,
** invoke it.
*/
static void vdbeInvokeSqllog(Vdbe *v){
if( sqlite3GlobalConfig.xSqllog && v->rc==SQLITE_OK && v->zSql && v->pc>=0 ){
char *zExpanded = sqlite3VdbeExpandSql(v, v->zSql);
assert( v->db->init.busy==0 );
if( zExpanded ){
sqlite3GlobalConfig.xSqllog(
sqlite3GlobalConfig.pSqllogArg, v->db, zExpanded, 1
);
sqlite3DbFree(v->db, zExpanded);
}
}
}
#else
# define vdbeInvokeSqllog(x)
#endif
** the P1 database. If the vacuum has finished, jump to instruction
** P2. Otherwise, fall through to the next instruction.
*/
case OP_IncrVacuum: { /* jump */
Btree *pBt;
assert( pOp->p1>=0 && pOp->p1<db->nDb );
assert( DbMaskTest(p->btreeMask, pOp->p1) );
assert( p->readOnly==0 );
pBt = db->aDb[pOp->p1].pBt;
rc = sqlite3BtreeIncrVacuum(pBt);
VdbeBranchTaken(rc==SQLITE_DONE,2);
if( rc ){
if( rc!=SQLITE_DONE ) goto abort_due_to_error;
rc = SQLITE_OK;
goto jump_to_p2;
}
break;
}
#endif
/* Opcode: Expire P1 P2 * * *
**
** Cause precompiled statements to expire. When an expired statement
** is executed using sqlite3_step() it will either automatically
** reprepare itself (if it was originally created using sqlite3_prepare_v2())
** or it will fail with SQLITE_SCHEMA.
**
** If P1 is 0, then all SQL statements become expired. If P1 is non-zero,
** then only the currently executing statement is expired.
**
** If P2 is 0, then SQL statements are expired immediately. If P2 is 1,
** then running SQL statements are allowed to continue to run to completion.
** The P2==1 case occurs when a CREATE INDEX or similar schema change happens
** that might help the statement run faster but which does not affect the
** correctness of operation.
*/
case OP_Expire: {
assert( pOp->p2==0 || pOp->p2==1 );
if( !pOp->p1 ){
sqlite3ExpirePreparedStatements(db, pOp->p2);
}else{
p->expired = pOp->p2+1;
}
break;
}
#ifndef SQLITE_OMIT_SHARED_CACHE
/* Opcode: TableLock P1 P2 P3 P4 *
** Synopsis: iDb=P1 root=P2 write=P3
**
** Obtain a lock on a particular table. This instruction is only used when
** the shared-cache feature is enabled.
**
** P1 is the index of the database in sqlite3.aDb[] of the database
** on which the lock is acquired. A readlock is obtained if P3==0 or
** a write lock if P3==1.
**
** P2 contains the root-page of the table to lock.
**
** P4 contains a pointer to the name of the table being locked. This is only
** used to generate an error message if the lock cannot be obtained.
*/
case OP_TableLock: {
u8 isWriteLock = (u8)pOp->p3;
if( isWriteLock || 0==(db->flags&SQLITE_ReadUncommit) ){
int p1 = pOp->p1;
assert( p1>=0 && p1<db->nDb );
assert( DbMaskTest(p->btreeMask, p1) );
assert( isWriteLock==0 || isWriteLock==1 );
rc = sqlite3BtreeLockTable(db->aDb[p1].pBt, pOp->p2, isWriteLock);
if( rc ){
if( (rc&0xFF)==SQLITE_LOCKED ){
const char *z = pOp->p4.z;
sqlite3VdbeError(p, "database table is locked: %s", z);
}
goto abort_due_to_error;
}
}
break;
}
#endif /* SQLITE_OMIT_SHARED_CACHE */
#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VBegin * * * P4 *
**
** P4 may be a pointer to an sqlite3_vtab structure. If so, call the
** xBegin method for that table.
**
** Also, whether or not P4 is set, check that this is not being called from
** within a callback to a virtual table xSync() method. If it is, the error
** code will be set to SQLITE_LOCKED.
*/
case OP_VBegin: {
VTable *pVTab;
pVTab = pOp->p4.pVtab;
rc = sqlite3VtabBegin(db, pVTab);
if( pVTab ) sqlite3VtabImportErrmsg(p, pVTab->pVtab);
if( rc ) goto abort_due_to_error;
break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */
#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VCreate P1 P2 * * *
**
** P2 is a register that holds the name of a virtual table in database
** P1. Call the xCreate method for that table.
*/
case OP_VCreate: {
Mem sMem; /* For storing the record being decoded */
const char *zTab; /* Name of the virtual table */
memset(&sMem, 0, sizeof(sMem));
sMem.db = db;
/* Because P2 is always a static string, it is impossible for the
** sqlite3VdbeMemCopy() to fail */
assert( (aMem[pOp->p2].flags & MEM_Str)!=0 );
assert( (aMem[pOp->p2].flags & MEM_Static)!=0 );
rc = sqlite3VdbeMemCopy(&sMem, &aMem[pOp->p2]);
assert( rc==SQLITE_OK );
zTab = (const char*)sqlite3_value_text(&sMem);
assert( zTab || db->mallocFailed );
if( zTab ){
rc = sqlite3VtabCallCreate(db, pOp->p1, zTab, &p->zErrMsg);
}
sqlite3VdbeMemRelease(&sMem);
if( rc ) goto abort_due_to_error;
break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */
#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VDestroy P1 * * P4 *
**
** Free the list of sorted records starting at pRecord.
*/
static void vdbeSorterRecordFree(sqlite3 *db, SorterRecord *pRecord){
SorterRecord *p;
SorterRecord *pNext;
for(p=pRecord; p; p=pNext){
pNext = p->u.pNext;
sqlite3DbFree(db, p);
}
}
/*
** Free all resources owned by the object indicated by argument pTask. All
** fields of *pTask are zeroed before returning.
*/
static void vdbeSortSubtaskCleanup(sqlite3 *db, SortSubtask *pTask){
sqlite3DbFree(db, pTask->pUnpacked);
#if SQLITE_MAX_WORKER_THREADS>0
/* pTask->list.aMemory can only be non-zero if it was handed memory
** from the main thread. That only occurs SQLITE_MAX_WORKER_THREADS>0 */
if( pTask->list.aMemory ){
sqlite3_free(pTask->list.aMemory);
}else
#endif
{
assert( pTask->list.aMemory==0 );
vdbeSorterRecordFree(0, pTask->list.pList);
}
if( pTask->file.pFd ){
sqlite3OsCloseFree(pTask->file.pFd);
}
if( pTask->file2.pFd ){
sqlite3OsCloseFree(pTask->file2.pFd);
}
memset(pTask, 0, sizeof(SortSubtask));
}
#ifdef SQLITE_DEBUG_SORTER_THREADS
static void vdbeSorterWorkDebug(SortSubtask *pTask, const char *zEvent){
i64 t;
int iTask = (pTask - pTask->pSorter->aTask);
sqlite3OsCurrentTimeInt64(pTask->pSorter->db->pVfs, &t);
fprintf(stderr, "%lld:%d %s\n", t, iTask, zEvent);
}
static void vdbeSorterRewindDebug(const char *zEvent){
i64 t;
sqlite3OsCurrentTimeInt64(sqlite3_vfs_find(0), &t);
fprintf(stderr, "%lld:X %s\n", t, zEvent);
}
static void vdbeSorterPopulateDebug(
SortSubtask *pTask,
const char *zEvent
){
i64 t;
int iTask = (pTask - pTask->pSorter->aTask);
sqlite3OsCurrentTimeInt64(pTask->pSorter->db->pVfs, &t);
fprintf(stderr, "%lld:bg%d %s\n", t, iTask, zEvent);
}
static void vdbeSorterBlockDebug(
SortSubtask *pTask,
int bBlocked,
const char *zEvent
){
if( bBlocked ){
i64 t;
sqlite3OsCurrentTimeInt64(pTask->pSorter->db->pVfs, &t);
fprintf(stderr, "%lld:main %s\n", t, zEvent);
}
}
#else
# define vdbeSorterWorkDebug(x,y)
# define vdbeSorterRewindDebug(y)
# define vdbeSorterPopulateDebug(x,y)
# define vdbeSorterBlockDebug(x,y,z)
#endif
#if SQLITE_MAX_WORKER_THREADS>0
/*
** Join thread pTask->thread.
*/
static int vdbeSorterJoinThread(SortSubtask *pTask){
int rc = SQLITE_OK;
if( pTask->pThread ){
#ifdef SQLITE_DEBUG_SORTER_THREADS
int bDone = pTask->bDone;
#endif
void *pRet = SQLITE_INT_TO_PTR(SQLITE_ERROR);
vdbeSorterBlockDebug(pTask, !bDone, "enter");
(void)sqlite3ThreadJoin(pTask->pThread, &pRet);
vdbeSorterBlockDebug(pTask, !bDone, "exit");
rc = SQLITE_PTR_TO_INT(pRet);
assert( pTask->bDone==1 );
pTask->bDone = 0;
pTask->pThread = 0;
}
return rc;
}
/*
** Launch a background thread to run xTask(pIn).
*/
static int vdbeSorterCreateThread(
SortSubtask *pTask, /* Thread will use this task object */
void *(*xTask)(void*), /* Routine to run in a separate thread */
void *pIn /* Argument passed into xTask() */
){
assert( pTask->pThread==0 && pTask->bDone==0 );
return sqlite3ThreadCreate(&pTask->pThread, xTask, pIn);
}
/*
** Join all outstanding threads launched by SorterWrite() to create
** level-0 PMAs.
*/
static int vdbeSorterJoinAll(VdbeSorter *pSorter, int rcin){
int rc = rcin;
int i;
/* This function is always called by the main user thread.
**
** If this function is being called after SorterRewind() has been called,
** it is possible that thread pSorter->aTask[pSorter->nTask-1].pThread
** is currently attempt to join one of the other threads. To avoid a race
** condition where this thread also attempts to join the same object, join
db->nDb = iDb;
if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
sqlite3OomFault(db);
sqlite3DbFree(db, zErrDyn);
zErrDyn = sqlite3MPrintf(db, "out of memory");
}else if( zErrDyn==0 ){
zErrDyn = sqlite3MPrintf(db, "unable to open database: %s", zFile);
}
}
goto attach_error;
}
return;
attach_error:
/* Return an error if we get here */
if( zErrDyn ){
sqlite3_result_error(context, zErrDyn, -1);
sqlite3DbFree(db, zErrDyn);
}
if( rc ) sqlite3_result_error_code(context, rc);
}
/*
** An SQL user-function registered to do the work of an DETACH statement. The
** three arguments to the function come directly from a detach statement:
**
** DETACH DATABASE x
**
** SELECT sqlite_detach(x)
*/
static void detachFunc(
sqlite3_context *context,
int NotUsed,
sqlite3_value **argv
){
const char *zName = (const char *)sqlite3_value_text(argv[0]);
sqlite3 *db = sqlite3_context_db_handle(context);
int i;
Db *pDb = 0;
char zErr[128];
UNUSED_PARAMETER(NotUsed);
if( zName==0 ) zName = "";
for(i=0; i<db->nDb; i++){
pDb = &db->aDb[i];
if( pDb->pBt==0 ) continue;
if( sqlite3StrICmp(pDb->zDbSName, zName)==0 ) break;
}
if( i>=db->nDb ){
sqlite3_snprintf(sizeof(zErr),zErr, "no such database: %s", zName);
goto detach_error;
}
if( i<2 ){
sqlite3_snprintf(sizeof(zErr),zErr, "cannot detach database %s", zName);
goto detach_error;
}
if( sqlite3BtreeIsInReadTrans(pDb->pBt) || sqlite3BtreeIsInBackup(pDb->pBt) ){
sqlite3_snprintf(sizeof(zErr),zErr, "database %s is locked", zName);
goto detach_error;
}
sqlite3BtreeClose(pDb->pBt);
pDb->pBt = 0;
pDb->pSchema = 0;
sqlite3CollapseDatabaseArray(db);
return;
detach_error:
sqlite3_result_error(context, zErr, -1);
}
/*
** This procedure generates VDBE code for a single invocation of either the
** sqlite_detach() or sqlite_attach() SQL user functions.
*/
static void codeAttach(
Parse *pParse, /* The parser context */
int type, /* Either SQLITE_ATTACH or SQLITE_DETACH */
FuncDef const *pFunc,/* FuncDef wrapper for detachFunc() or attachFunc() */
Expr *pAuthArg, /* Expression to pass to authorization callback */
Expr *pFilename, /* Name of database file */
Expr *pDbname, /* Name of the database to use internally */
Expr *pKey /* Database key for encryption extension */
){
int rc;
NameContext sName;
Vdbe *v;
sqlite3* db = pParse->db;
int regArgs;
if( pParse->nErr ) goto attach_end;
memset(&sName, 0, sizeof(NameContext));
sName.pParse = pParse;
if(
SQLITE_OK!=(rc = resolveAttachExpr(&sName, pFilename)) ||
SQLITE_OK!=(rc = resolveAttachExpr(&sName, pDbname)) ||
SQLITE_OK!=(rc = resolveAttachExpr(&sName, pKey))
){
goto attach_end;
}
#ifndef SQLITE_OMIT_AUTHORIZATION
if( pAuthArg ){
char *zAuthArg;
if( pAuthArg->op==TK_STRING ){
zAuthArg = pAuthArg->u.zToken;
}else{
zAuthArg = 0;
}
rc = sqlite3AuthCheck(pParse, type, zAuthArg, 0, 0);
if(rc!=SQLITE_OK ){
goto attach_end;
}
}
#endif /* SQLITE_OMIT_AUTHORIZATION */
** popped. Or if pParse==0, this routine is a no-op.
*/
SQLITE_PRIVATE void sqlite3AuthContextPush(
Parse *pParse,
AuthContext *pContext,
const char *zContext
){
assert( pParse );
pContext->pParse = pParse;
pContext->zAuthContext = pParse->zAuthContext;
pParse->zAuthContext = zContext;
}
/*
** Pop an authorization context that was previously pushed
** by sqlite3AuthContextPush
*/
SQLITE_PRIVATE void sqlite3AuthContextPop(AuthContext *pContext){
if( pContext->pParse ){
pContext->pParse->zAuthContext = pContext->zAuthContext;
pContext->pParse = 0;
}
}
#endif /* SQLITE_OMIT_AUTHORIZATION */
/************** End of auth.c ************************************************/
/************** Begin file build.c *******************************************/
/*
** 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 file contains C code routines that are called by the SQLite parser
** when syntax rules are reduced. The routines in this file handle the
** following kinds of SQL syntax:
**
** CREATE TABLE
** DROP TABLE
** CREATE INDEX
** DROP INDEX
** creating ID lists
** BEGIN TRANSACTION
** COMMIT
** ROLLBACK
*/
/* #include "sqliteInt.h" */
#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** The TableLock structure is only used by the sqlite3TableLock() and
** codeTableLocks() functions.
*/
struct TableLock {
int iDb; /* The database containing the table to be locked */
int iTab; /* The root page of the table to be locked */
u8 isWriteLock; /* True for write lock. False for a read lock */
const char *zLockName; /* Name of the table */
};
/*
** Record the fact that we want to lock a table at run-time.
**
** The table to be locked has root page iTab and is found in database iDb.
** A read or a write lock can be taken depending on isWritelock.
**
** This routine just records the fact that the lock is desired. The
** code to make the lock occur is generated by a later call to
** codeTableLocks() which occurs during sqlite3FinishCoding().
*/
SQLITE_PRIVATE void sqlite3TableLock(
Parse *pParse, /* Parsing context */
int iDb, /* Index of the database containing the table to lock */
int iTab, /* Root page number of the table to be locked */
u8 isWriteLock, /* True for a write lock */
const char *zName /* Name of the table to be locked */
){
Parse *pToplevel = sqlite3ParseToplevel(pParse);
int i;
int nBytes;
TableLock *p;
assert( iDb>=0 );
if( iDb==1 ) return;
if( !sqlite3BtreeSharable(pParse->db->aDb[iDb].pBt) ) return;
for(i=0; i<pToplevel->nTableLock; i++){
p = &pToplevel->aTableLock[i];
if( p->iDb==iDb && p->iTab==iTab ){
p->isWriteLock = (p->isWriteLock || isWriteLock);
return;
}
}
nBytes = sizeof(TableLock) * (pToplevel->nTableLock+1);
pToplevel->aTableLock =
sqlite3DbReallocOrFree(pToplevel->db, pToplevel->aTableLock, nBytes);
if( pToplevel->aTableLock ){
p = &pToplevel->aTableLock[pToplevel->nTableLock++];
p->iDb = iDb;
p->iTab = iTab;
p->isWriteLock = isWriteLock;
p->zLockName = zName;
}else{
pToplevel->nTableLock = 0;
sqlite3OomFault(pToplevel->db);
}
}
/*
** Code an OP_TableLock instruction for each table locked by the
** statement (configured by calls to sqlite3TableLock()).
*/
static void codeTableLocks(Parse *pParse){
int i;
Vdbe *pVdbe;
pVdbe = sqlite3GetVdbe(pParse);
assert( pVdbe!=0 ); /* sqlite3GetVdbe cannot fail: VDBE already allocated */
for(i=0; i<pParse->nTableLock; i++){
TableLock *p = &pParse->aTableLock[i];
int p1 = p->iDb;
sqlite3VdbeAddOp4(pVdbe, OP_TableLock, p1, p->iTab, p->isWriteLock,
p->zLockName, P4_STATIC);
}
}
#else
#define codeTableLocks(x)
#endif
/*
** Return TRUE if the given yDbMask object is empty - if it contains no
** 1 bits. This routine is used by the DbMaskAllZero() and DbMaskNotZero()
** macros when SQLITE_MAX_ATTACHED is greater than 30.
*/
#if SQLITE_MAX_ATTACHED>30
SQLITE_PRIVATE int sqlite3DbMaskAllZero(yDbMask m){
int i;
for(i=0; i<sizeof(yDbMask); i++) if( m[i] ) return 0;
return 1;
}
#endif
/*
** This routine is called after a single SQL statement has been
** parsed and a VDBE program to execute that statement has been
** prepared. This routine puts the finishing touches on the
** VDBE program and resets the pParse structure for the next
** parse.
**
** Note that if an error occurred, it might be the case that
** no VDBE code was generated.
*/
SQLITE_PRIVATE void sqlite3FinishCoding(Parse *pParse){
sqlite3 *db;
Vdbe *v;
assert( pParse->pToplevel==0 );
db = pParse->db;
if( pParse->nested ) return;
if( db->mallocFailed || pParse->nErr ){
if( pParse->rc==SQLITE_OK ) pParse->rc = SQLITE_ERROR;
return;
}
/* Begin by generating some termination code at the end of the
** vdbe program
*/
v = sqlite3GetVdbe(pParse);
assert( !pParse->isMultiWrite
**
** Call sqlite3_busy_timeout(db, N). Return the current timeout value
** if one is set. If no busy handler or a different busy handler is set
** then 0 is returned. Setting the busy_timeout to 0 or negative
** disables the timeout.
*/
/*case PragTyp_BUSY_TIMEOUT*/ default: {
assert( pPragma->ePragTyp==PragTyp_BUSY_TIMEOUT );
if( zRight ){
sqlite3_busy_timeout(db, sqlite3Atoi(zRight));
}
returnSingleInt(v, db->busyTimeout);
break;
}
/*
** PRAGMA soft_heap_limit
** PRAGMA soft_heap_limit = N
**
** IMPLEMENTATION-OF: R-26343-45930 This pragma invokes the
** sqlite3_soft_heap_limit64() interface with the argument N, if N is
** specified and is a non-negative integer.
** IMPLEMENTATION-OF: R-64451-07163 The soft_heap_limit pragma always
** returns the same integer that would be returned by the
** sqlite3_soft_heap_limit64(-1) C-language function.
*/
case PragTyp_SOFT_HEAP_LIMIT: {
sqlite3_int64 N;
if( zRight && sqlite3DecOrHexToI64(zRight, &N)==SQLITE_OK ){
sqlite3_soft_heap_limit64(N);
}
returnSingleInt(v, sqlite3_soft_heap_limit64(-1));
break;
}
/*
** PRAGMA threads
** PRAGMA threads = N
**
** Configure the maximum number of worker threads. Return the new
** maximum, which might be less than requested.
*/
case PragTyp_THREADS: {
sqlite3_int64 N;
if( zRight
&& sqlite3DecOrHexToI64(zRight, &N)==SQLITE_OK
&& N>=0
){
sqlite3_limit(db, SQLITE_LIMIT_WORKER_THREADS, (int)(N&0x7fffffff));
}
returnSingleInt(v, sqlite3_limit(db, SQLITE_LIMIT_WORKER_THREADS, -1));
break;
}
#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
/*
** Report the current state of file logs for all databases
*/
case PragTyp_LOCK_STATUS: {
static const char *const azLockName[] = {
"unlocked", "shared", "reserved", "pending", "exclusive"
};
int i;
pParse->nMem = 2;
for(i=0; i<db->nDb; i++){
Btree *pBt;
const char *zState = "unknown";
int j;
if( db->aDb[i].zDbSName==0 ) continue;
pBt = db->aDb[i].pBt;
if( pBt==0 || sqlite3BtreePager(pBt)==0 ){
zState = "closed";
}else if( sqlite3_file_control(db, i ? db->aDb[i].zDbSName : 0,
SQLITE_FCNTL_LOCKSTATE, &j)==SQLITE_OK ){
zState = azLockName[j];
}
sqlite3VdbeMultiLoad(v, 1, "ss", db->aDb[i].zDbSName, zState);
}
break;
}
#endif
#ifdef SQLITE_HAS_CODEC
/* Pragma iArg
** ---------- ------
** key 0
** rekey 1
** hexkey 2
** hexrekey 3
** textkey 4
** textrekey 5
*/
case PragTyp_KEY: {
if( zRight ){
int n = pPragma->iArg<4 ? sqlite3Strlen30(zRight) : -1;
if( (pPragma->iArg & 1)==0 ){
sqlite3_key_v2(db, zDb, zRight, n);
}else{
sqlite3_rekey_v2(db, zDb, zRight, n);
}
}
break;
}
case PragTyp_HEXKEY: {
if( zRight ){
u8 iByte;
int i;
char zKey[40];
for(i=0, iByte=0; i<sizeof(zKey)*2 && sqlite3Isxdigit(zRight[i]); i++){
iByte = (iByte<<4) + sqlite3HexToInt(zRight[i]);
if( (i&1)!=0 ) zKey[i/2] = iByte;
}
if( (pPragma->iArg & 1)==0 ){
sqlite3_key_v2(db, zDb, zKey, i/2);
}else{
sqlite3_rekey_v2(db, zDb, zKey, i/2);
}
}
break;
}
#endif
*/
static int sqlite3Prepare(
sqlite3 *db, /* Database handle. */
const char *zSql, /* UTF-8 encoded SQL statement. */
int nBytes, /* Length of zSql in bytes. */
u32 prepFlags, /* Zero or more SQLITE_PREPARE_* flags */
Vdbe *pReprepare, /* VM being reprepared */
sqlite3_stmt **ppStmt, /* OUT: A pointer to the prepared statement */
const char **pzTail /* OUT: End of parsed string */
){
char *zErrMsg = 0; /* Error message */
int rc = SQLITE_OK; /* Result code */
int i; /* Loop counter */
Parse sParse; /* Parsing context */
memset(&sParse, 0, PARSE_HDR_SZ);
memset(PARSE_TAIL(&sParse), 0, PARSE_TAIL_SZ);
sParse.pReprepare = pReprepare;
assert( ppStmt && *ppStmt==0 );
/* assert( !db->mallocFailed ); // not true with SQLITE_USE_ALLOCA */
assert( sqlite3_mutex_held(db->mutex) );
/* For a long-term use prepared statement avoid the use of
** lookaside memory.
*/
if( prepFlags & SQLITE_PREPARE_PERSISTENT ){
sParse.disableLookaside++;
db->lookaside.bDisable++;
}
/* Check to verify that it is possible to get a read lock on all
** database schemas. The inability to get a read lock indicates that
** some other database connection is holding a write-lock, which in
** turn means that the other connection has made uncommitted changes
** to the schema.
**
** Were we to proceed and prepare the statement against the uncommitted
** schema changes and if those schema changes are subsequently rolled
** back and different changes are made in their place, then when this
** prepared statement goes to run the schema cookie would fail to detect
** the schema change. Disaster would follow.
**
** This thread is currently holding mutexes on all Btrees (because
** of the sqlite3BtreeEnterAll() in sqlite3LockAndPrepare()) so it
** is not possible for another thread to start a new schema change
** while this routine is running. Hence, we do not need to hold
** locks on the schema, we just need to make sure nobody else is
** holding them.
**
** Note that setting READ_UNCOMMITTED overrides most lock detection,
** but it does *not* override schema lock detection, so this all still
** works even if READ_UNCOMMITTED is set.
*/
for(i=0; i<db->nDb; i++) {
Btree *pBt = db->aDb[i].pBt;
if( pBt ){
assert( sqlite3BtreeHoldsMutex(pBt) );
rc = sqlite3BtreeSchemaLocked(pBt);
if( rc ){
const char *zDb = db->aDb[i].zDbSName;
sqlite3ErrorWithMsg(db, rc, "database schema is locked: %s", zDb);
testcase( db->flags & SQLITE_ReadUncommit );
goto end_prepare;
}
}
}
sqlite3VtabUnlockList(db);
sParse.db = db;
if( nBytes>=0 && (nBytes==0 || zSql[nBytes-1]!=0) ){
char *zSqlCopy;
int mxLen = db->aLimit[SQLITE_LIMIT_SQL_LENGTH];
testcase( nBytes==mxLen );
testcase( nBytes==mxLen+1 );
if( nBytes>mxLen ){
sqlite3ErrorWithMsg(db, SQLITE_TOOBIG, "statement too long");
rc = sqlite3ApiExit(db, SQLITE_TOOBIG);
goto end_prepare;
}
zSqlCopy = sqlite3DbStrNDup(db, zSql, nBytes);
if( zSqlCopy ){
sqlite3RunParser(&sParse, zSqlCopy, &zErrMsg);
sParse.zTail = &zSql[sParse.zTail-zSqlCopy];
sqlite3DbFree(db, zSqlCopy);
}else{
sParse.zTail = &zSql[nBytes];
}
}else{
sqlite3RunParser(&sParse, zSql, &zErrMsg);
}
assert( 0==sParse.nQueryLoop );
if( sParse.rc==SQLITE_DONE ) sParse.rc = SQLITE_OK;
if( sParse.checkSchema ){
schemaIsValid(&sParse);
}
if( db->mallocFailed ){
sParse.rc = SQLITE_NOMEM_BKPT;
}
if( pzTail ){
*pzTail = sParse.zTail;
}
rc = sParse.rc;
#ifndef SQLITE_OMIT_EXPLAIN
if( rc==SQLITE_OK && sParse.pVdbe && sParse.explain ){
static const char * const azColName[] = {
"addr", "opcode", "p1", "p2", "p3", "p4", "p5", "comment",
"id", "parent", "notused", "detail"
};
int iFirst, mx;
if( sParse.explain==2 ){
sqlite3VdbeSetNumCols(sParse.pVdbe, 4);
iFirst = 8;
mx = 12;
}else{
sqlite3VdbeSetNumCols(sParse.pVdbe, 8);
iFirst = 0;
mx = 8;
}
case TK_COMMA:
case TK_BITAND:
case TK_BITNOT:
case TK_DOT:
case TK_IN:
case TK_IS:
case TK_NOT:
case TK_NULL:
case TK_ID: {
if( tokenType==TK_NULL ){
if( prevTokenType==TK_IS || prevTokenType==TK_NOT ){
/* NULL is a keyword in this case, not a literal value */
}else{
/* Here the NULL is a literal value */
z[j++] = '?';
break;
}
}
if( j>0 && sqlite3IsIdChar(z[j-1]) && sqlite3IsIdChar(zSql[i]) ){
z[j++] = ' ';
}
if( tokenType==TK_ID ){
int i2 = i, n2 = n, rc = SQLITE_OK;
if( nParen>0 ){
assert( nParen<nSql );
sqlite3HashInsert(&inHash, zSql+nParen, 0);
}
if( flags&SQLITE_TOKEN_QUOTED ){ i2++; n2-=2; }
if( shouldTreatAsIdentifier(db, zSql+i2, n2, &rc)==0 ){
if( rc!=SQLITE_OK ){
sqlite3DbFree(db, z);
sqlite3HashClear(&inHash);
return;
}
if( sqlite3_keyword_check(zSql+i2, n2)==0 ){
z[j++] = '?';
break;
}
}
}
copyNormalizedToken(zSql, i, n, flags, z, &j);
break;
}
}
}
assert( j<nZ && "one" );
while( j>0 && z[j-1]==' ' ){ j--; }
if( j>0 && z[j-1]!=';' ){ z[j++] = ';'; }
z[j] = 0;
assert( j<nZ && "two" );
pVdbe->zNormSql = z;
sqlite3HashClear(&inHash);
}
#endif /* SQLITE_ENABLE_NORMALIZE */
/*
** Rerun the compilation of a statement after a schema change.
**
** If the statement is successfully recompiled, return SQLITE_OK. Otherwise,
** if the statement cannot be recompiled because another connection has
** locked the sqlite3_master table, return SQLITE_LOCKED. If any other error
** occurs, return SQLITE_SCHEMA.
*/
SQLITE_PRIVATE int sqlite3Reprepare(Vdbe *p){
int rc;
sqlite3_stmt *pNew;
const char *zSql;
sqlite3 *db;
u8 prepFlags;
assert( sqlite3_mutex_held(sqlite3VdbeDb(p)->mutex) );
zSql = sqlite3_sql((sqlite3_stmt *)p);
assert( zSql!=0 ); /* Reprepare only called for prepare_v2() statements */
db = sqlite3VdbeDb(p);
assert( sqlite3_mutex_held(db->mutex) );
prepFlags = sqlite3VdbePrepareFlags(p);
rc = sqlite3LockAndPrepare(db, zSql, -1, prepFlags, p, &pNew, 0);
if( rc ){
if( rc==SQLITE_NOMEM ){
sqlite3OomFault(db);
}
assert( pNew==0 );
return rc;
}else{
assert( pNew!=0 );
}
sqlite3VdbeSwap((Vdbe*)pNew, p);
sqlite3TransferBindings(pNew, (sqlite3_stmt*)p);
sqlite3VdbeResetStepResult((Vdbe*)pNew);
sqlite3VdbeFinalize((Vdbe*)pNew);
return SQLITE_OK;
}
/*
** Two versions of the official API. Legacy and new use. In the legacy
** version, the original SQL text is not saved in the prepared statement
** and so if a schema change occurs, SQLITE_SCHEMA is returned by
** sqlite3_step(). In the new version, the original SQL text is retained
** and the statement is automatically recompiled if an schema change
** occurs.
*/
SQLITE_API int sqlite3_prepare(
sqlite3 *db, /* Database handle. */
const char *zSql, /* UTF-8 encoded SQL statement. */
int nBytes, /* Length of zSql in bytes. */
sqlite3_stmt **ppStmt, /* OUT: A pointer to the prepared statement */
const char **pzTail /* OUT: End of parsed string */
){
int rc;
rc = sqlite3LockAndPrepare(db,zSql,nBytes,0,0,ppStmt,pzTail);
assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 ); /* VERIFY: F13021 */
return rc;
}
SQLITE_API int sqlite3_prepare_v2(
sqlite3 *db, /* Database handle. */
const char *zSql, /* UTF-8 encoded SQL statement. */
int nBytes, /* Length of zSql in bytes. */
sqlite3_stmt **ppStmt, /* OUT: A pointer to the prepared statement */
const char **pzTail /* OUT: End of parsed string */
){
u32 saved_flags; /* Saved value of db->flags */
int saved_nChange; /* Saved value of db->nChange */
int saved_nTotalChange; /* Saved value of db->nTotalChange */
u8 saved_mTrace; /* Saved trace settings */
Db *pDb = 0; /* Database to detach at end of vacuum */
int isMemDb; /* True if vacuuming a :memory: database */
int nRes; /* Bytes of reserved space at the end of each page */
int nDb; /* Number of attached databases */
const char *zDbMain; /* Schema name of database to vacuum */
if( !db->autoCommit ){
sqlite3SetString(pzErrMsg, db, "cannot VACUUM from within a transaction");
return SQLITE_ERROR;
}
if( db->nVdbeActive>1 ){
sqlite3SetString(pzErrMsg, db,"cannot VACUUM - SQL statements in progress");
return SQLITE_ERROR;
}
/* Save the current value of the database flags so that it can be
** restored before returning. Then set the writable-schema flag, and
** disable CHECK and foreign key constraints. */
saved_flags = db->flags;
saved_mDbFlags = db->mDbFlags;
saved_nChange = db->nChange;
saved_nTotalChange = db->nTotalChange;
saved_mTrace = db->mTrace;
db->flags |= SQLITE_WriteSchema | SQLITE_IgnoreChecks;
db->mDbFlags |= DBFLAG_PreferBuiltin | DBFLAG_Vacuum;
db->flags &= ~(SQLITE_ForeignKeys | SQLITE_ReverseOrder
| SQLITE_Defensive | SQLITE_CountRows);
db->mTrace = 0;
zDbMain = db->aDb[iDb].zDbSName;
pMain = db->aDb[iDb].pBt;
isMemDb = sqlite3PagerIsMemdb(sqlite3BtreePager(pMain));
/* Attach the temporary database as 'vacuum_db'. The synchronous pragma
** can be set to 'off' for this file, as it is not recovered if a crash
** occurs anyway. The integrity of the database is maintained by a
** (possibly synchronous) transaction opened on the main database before
** sqlite3BtreeCopyFile() is called.
**
** An optimisation would be to use a non-journaled pager.
** (Later:) I tried setting "PRAGMA vacuum_db.journal_mode=OFF" but
** that actually made the VACUUM run slower. Very little journalling
** actually occurs when doing a vacuum since the vacuum_db is initially
** empty. Only the journal header is written. Apparently it takes more
** time to parse and run the PRAGMA to turn journalling off than it does
** to write the journal header file.
*/
nDb = db->nDb;
rc = execSql(db, pzErrMsg, "ATTACH''AS vacuum_db");
if( rc!=SQLITE_OK ) goto end_of_vacuum;
assert( (db->nDb-1)==nDb );
pDb = &db->aDb[nDb];
assert( strcmp(pDb->zDbSName,"vacuum_db")==0 );
pTemp = pDb->pBt;
/* The call to execSql() to attach the temp database has left the file
** locked (as there was more than one active statement when the transaction
** to read the schema was concluded. Unlock it here so that this doesn't
** cause problems for the call to BtreeSetPageSize() below. */
sqlite3BtreeCommit(pTemp);
nRes = sqlite3BtreeGetOptimalReserve(pMain);
/* A VACUUM cannot change the pagesize of an encrypted database. */
#ifdef SQLITE_HAS_CODEC
if( db->nextPagesize ){
extern void sqlite3CodecGetKey(sqlite3*, int, void**, int*);
int nKey;
char *zKey;
sqlite3CodecGetKey(db, iDb, (void**)&zKey, &nKey);
if( nKey ) db->nextPagesize = 0;
}
#endif
sqlite3BtreeSetCacheSize(pTemp, db->aDb[iDb].pSchema->cache_size);
sqlite3BtreeSetSpillSize(pTemp, sqlite3BtreeSetSpillSize(pMain,0));
sqlite3BtreeSetPagerFlags(pTemp, PAGER_SYNCHRONOUS_OFF|PAGER_CACHESPILL);
/* Begin a transaction and take an exclusive lock on the main database
** file. This is done before the sqlite3BtreeGetPageSize(pMain) call below,
** to ensure that we do not try to change the page-size on a WAL database.
*/
rc = execSql(db, pzErrMsg, "BEGIN");
if( rc!=SQLITE_OK ) goto end_of_vacuum;
rc = sqlite3BtreeBeginTrans(pMain, 2, 0);
if( rc!=SQLITE_OK ) goto end_of_vacuum;
/* Do not attempt to change the page size for a WAL database */
if( sqlite3PagerGetJournalMode(sqlite3BtreePager(pMain))
==PAGER_JOURNALMODE_WAL ){
db->nextPagesize = 0;
}
if( sqlite3BtreeSetPageSize(pTemp, sqlite3BtreeGetPageSize(pMain), nRes, 0)
|| (!isMemDb && sqlite3BtreeSetPageSize(pTemp, db->nextPagesize, nRes, 0))
|| NEVER(db->mallocFailed)
){
rc = SQLITE_NOMEM_BKPT;
goto end_of_vacuum;
}
#ifndef SQLITE_OMIT_AUTOVACUUM
sqlite3BtreeSetAutoVacuum(pTemp, db->nextAutovac>=0 ? db->nextAutovac :
sqlite3BtreeGetAutoVacuum(pMain));
#endif
/* Query the schema of the main database. Create a mirror schema
** in the temporary database.
*/
db->init.iDb = nDb; /* force new CREATE statements into vacuum_db */
rc = execSqlF(db, pzErrMsg,
"SELECT sql FROM \"%w\".sqlite_master"
" WHERE type='table'AND name<>'sqlite_sequence'"
" AND coalesce(rootpage,1)>0",
zDbMain
);
if( rc!=SQLITE_OK ) goto end_of_vacuum;
** sqlite3_create_module_v2() interfaces.
*/
static int createModule(
sqlite3 *db, /* Database in which module is registered */
const char *zName, /* Name assigned to this module */
const sqlite3_module *pModule, /* The definition of the module */
void *pAux, /* Context pointer for xCreate/xConnect */
void (*xDestroy)(void *) /* Module destructor function */
){
int rc = SQLITE_OK;
sqlite3_mutex_enter(db->mutex);
if( sqlite3HashFind(&db->aModule, zName) ){
rc = SQLITE_MISUSE_BKPT;
}else{
(void)sqlite3VtabCreateModule(db, zName, pModule, pAux, xDestroy);
}
rc = sqlite3ApiExit(db, rc);
if( rc!=SQLITE_OK && xDestroy ) xDestroy(pAux);
sqlite3_mutex_leave(db->mutex);
return rc;
}
/*
** External API function used to create a new virtual-table module.
*/
SQLITE_API int sqlite3_create_module(
sqlite3 *db, /* Database in which module is registered */
const char *zName, /* Name assigned to this module */
const sqlite3_module *pModule, /* The definition of the module */
void *pAux /* Context pointer for xCreate/xConnect */
){
#ifdef SQLITE_ENABLE_API_ARMOR
if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
#endif
return createModule(db, zName, pModule, pAux, 0);
}
/*
** External API function used to create a new virtual-table module.
*/
SQLITE_API int sqlite3_create_module_v2(
sqlite3 *db, /* Database in which module is registered */
const char *zName, /* Name assigned to this module */
const sqlite3_module *pModule, /* The definition of the module */
void *pAux, /* Context pointer for xCreate/xConnect */
void (*xDestroy)(void *) /* Module destructor function */
){
#ifdef SQLITE_ENABLE_API_ARMOR
if( !sqlite3SafetyCheckOk(db) || zName==0 ) return SQLITE_MISUSE_BKPT;
#endif
return createModule(db, zName, pModule, pAux, xDestroy);
}
/*
** Lock the virtual table so that it cannot be disconnected.
** Locks nest. Every lock should have a corresponding unlock.
** If an unlock is omitted, resources leaks will occur.
**
** If a disconnect is attempted while a virtual table is locked,
** the disconnect is deferred until all locks have been removed.
*/
SQLITE_PRIVATE void sqlite3VtabLock(VTable *pVTab){
pVTab->nRef++;
}
/*
** pTab is a pointer to a Table structure representing a virtual-table.
** Return a pointer to the VTable object used by connection db to access
** this virtual-table, if one has been created, or NULL otherwise.
*/
SQLITE_PRIVATE VTable *sqlite3GetVTable(sqlite3 *db, Table *pTab){
VTable *pVtab;
assert( IsVirtual(pTab) );
for(pVtab=pTab->pVTable; pVtab && pVtab->db!=db; pVtab=pVtab->pNext);
return pVtab;
}
/*
** Decrement the ref-count on a virtual table object. When the ref-count
** reaches zero, call the xDisconnect() method to delete the object.
*/
SQLITE_PRIVATE void sqlite3VtabUnlock(VTable *pVTab){
sqlite3 *db = pVTab->db;
assert( db );
assert( pVTab->nRef>0 );
assert( db->magic==SQLITE_MAGIC_OPEN || db->magic==SQLITE_MAGIC_ZOMBIE );
pVTab->nRef--;
if( pVTab->nRef==0 ){
sqlite3_vtab *p = pVTab->pVtab;
if( p ){
p->pModule->xDisconnect(p);
}
sqlite3DbFree(db, pVTab);
}
}
/*
** Table p is a virtual table. This function moves all elements in the
** p->pVTable list to the sqlite3.pDisconnect lists of their associated
** database connections to be disconnected at the next opportunity.
** Except, if argument db is not NULL, then the entry associated with
** connection db is left in the p->pVTable list.
*/
static VTable *vtabDisconnectAll(sqlite3 *db, Table *p){
VTable *pRet = 0;
VTable *pVTable = p->pVTable;
p->pVTable = 0;
/* Assert that the mutex (if any) associated with the BtShared database
** that contains table p is held by the caller. See header comments
** above function sqlite3VtabUnlockList() for an explanation of why
** this makes it safe to access the sqlite3.pDisconnect list of any
** database connection that may have an entry in the p->pVTable list.
*/
assert( db==0 || sqlite3SchemaMutexHeld(db, 0, p->pSchema) );
case SQLITE_CANTOPEN_NOTEMPDIR: zName = "SQLITE_CANTOPEN_NOTEMPDIR";break;
case SQLITE_CANTOPEN_ISDIR: zName = "SQLITE_CANTOPEN_ISDIR"; break;
case SQLITE_CANTOPEN_FULLPATH: zName = "SQLITE_CANTOPEN_FULLPATH"; break;
case SQLITE_CANTOPEN_CONVPATH: zName = "SQLITE_CANTOPEN_CONVPATH"; break;
case SQLITE_PROTOCOL: zName = "SQLITE_PROTOCOL"; break;
case SQLITE_EMPTY: zName = "SQLITE_EMPTY"; break;
case SQLITE_SCHEMA: zName = "SQLITE_SCHEMA"; break;
case SQLITE_TOOBIG: zName = "SQLITE_TOOBIG"; break;
case SQLITE_CONSTRAINT: zName = "SQLITE_CONSTRAINT"; break;
case SQLITE_CONSTRAINT_UNIQUE: zName = "SQLITE_CONSTRAINT_UNIQUE"; break;
case SQLITE_CONSTRAINT_TRIGGER: zName = "SQLITE_CONSTRAINT_TRIGGER";break;
case SQLITE_CONSTRAINT_FOREIGNKEY:
zName = "SQLITE_CONSTRAINT_FOREIGNKEY"; break;
case SQLITE_CONSTRAINT_CHECK: zName = "SQLITE_CONSTRAINT_CHECK"; break;
case SQLITE_CONSTRAINT_PRIMARYKEY:
zName = "SQLITE_CONSTRAINT_PRIMARYKEY"; break;
case SQLITE_CONSTRAINT_NOTNULL: zName = "SQLITE_CONSTRAINT_NOTNULL";break;
case SQLITE_CONSTRAINT_COMMITHOOK:
zName = "SQLITE_CONSTRAINT_COMMITHOOK"; break;
case SQLITE_CONSTRAINT_VTAB: zName = "SQLITE_CONSTRAINT_VTAB"; break;
case SQLITE_CONSTRAINT_FUNCTION:
zName = "SQLITE_CONSTRAINT_FUNCTION"; break;
case SQLITE_CONSTRAINT_ROWID: zName = "SQLITE_CONSTRAINT_ROWID"; break;
case SQLITE_MISMATCH: zName = "SQLITE_MISMATCH"; break;
case SQLITE_MISUSE: zName = "SQLITE_MISUSE"; break;
case SQLITE_NOLFS: zName = "SQLITE_NOLFS"; break;
case SQLITE_AUTH: zName = "SQLITE_AUTH"; break;
case SQLITE_FORMAT: zName = "SQLITE_FORMAT"; break;
case SQLITE_RANGE: zName = "SQLITE_RANGE"; break;
case SQLITE_NOTADB: zName = "SQLITE_NOTADB"; break;
case SQLITE_ROW: zName = "SQLITE_ROW"; break;
case SQLITE_NOTICE: zName = "SQLITE_NOTICE"; break;
case SQLITE_NOTICE_RECOVER_WAL: zName = "SQLITE_NOTICE_RECOVER_WAL";break;
case SQLITE_NOTICE_RECOVER_ROLLBACK:
zName = "SQLITE_NOTICE_RECOVER_ROLLBACK"; break;
case SQLITE_WARNING: zName = "SQLITE_WARNING"; break;
case SQLITE_WARNING_AUTOINDEX: zName = "SQLITE_WARNING_AUTOINDEX"; break;
case SQLITE_DONE: zName = "SQLITE_DONE"; break;
}
}
if( zName==0 ){
static char zBuf[50];
sqlite3_snprintf(sizeof(zBuf), zBuf, "SQLITE_UNKNOWN(%d)", origRc);
zName = zBuf;
}
return zName;
}
#endif
/*
** Return a static string that describes the kind of error specified in the
** argument.
*/
SQLITE_PRIVATE const char *sqlite3ErrStr(int rc){
static const char* const aMsg[] = {
/* SQLITE_OK */ "not an error",
/* SQLITE_ERROR */ "SQL logic error",
/* SQLITE_INTERNAL */ 0,
/* SQLITE_PERM */ "access permission denied",
/* SQLITE_ABORT */ "query aborted",
/* SQLITE_BUSY */ "database is locked",
/* SQLITE_LOCKED */ "database table is locked",
/* SQLITE_NOMEM */ "out of memory",
/* SQLITE_READONLY */ "attempt to write a readonly database",
/* SQLITE_INTERRUPT */ "interrupted",
/* SQLITE_IOERR */ "disk I/O error",
/* SQLITE_CORRUPT */ "database disk image is malformed",
/* SQLITE_NOTFOUND */ "unknown operation",
/* SQLITE_FULL */ "database or disk is full",
/* SQLITE_CANTOPEN */ "unable to open database file",
/* SQLITE_PROTOCOL */ "locking protocol",
/* SQLITE_EMPTY */ 0,
/* SQLITE_SCHEMA */ "database schema has changed",
/* SQLITE_TOOBIG */ "string or blob too big",
/* SQLITE_CONSTRAINT */ "constraint failed",
/* SQLITE_MISMATCH */ "datatype mismatch",
/* SQLITE_MISUSE */ "bad parameter or other API misuse",
#ifdef SQLITE_DISABLE_LFS
/* SQLITE_NOLFS */ "large file support is disabled",
#else
/* SQLITE_NOLFS */ 0,
#endif
/* SQLITE_AUTH */ "authorization denied",
/* SQLITE_FORMAT */ 0,
/* SQLITE_RANGE */ "column index out of range",
/* SQLITE_NOTADB */ "file is not a database",
/* SQLITE_NOTICE */ "notification message",
/* SQLITE_WARNING */ "warning message",
};
const char *zErr = "unknown error";
switch( rc ){
case SQLITE_ABORT_ROLLBACK: {
zErr = "abort due to ROLLBACK";
break;
}
case SQLITE_ROW: {
zErr = "another row available";
break;
}
case SQLITE_DONE: {
zErr = "no more rows available";
break;
}
default: {
rc &= 0xff;
if( ALWAYS(rc>=0) && rc<ArraySize(aMsg) && aMsg[rc]!=0 ){
zErr = aMsg[rc];
}
break;
}
}
return zErr;
}
/*
** This routine implements a busy callback that sleeps and tries
** again until a timeout value is reached. The timeout value is
** an integer number of milliseconds passed in as the first
** argument.
**
** Return non-zero to retry the lock. Return zero to stop trying
** and cause SQLite to return SQLITE_BUSY.
#endif
azCompileOpt = sqlite3CompileOptions(&nOpt);
if( sqlite3StrNICmp(zOptName, "SQLITE_", 7)==0 ) zOptName += 7;
n = sqlite3Strlen30(zOptName);
/* Since nOpt is normally in single digits, a linear search is
** adequate. No need for a binary search. */
for(i=0; i<nOpt; i++){
if( sqlite3StrNICmp(zOptName, azCompileOpt[i], n)==0
&& sqlite3IsIdChar((unsigned char)azCompileOpt[i][n])==0
){
return 1;
}
}
return 0;
}
/*
** Return the N-th compile-time option string. If N is out of range,
** return a NULL pointer.
*/
SQLITE_API const char *sqlite3_compileoption_get(int N){
int nOpt;
const char **azCompileOpt;
azCompileOpt = sqlite3CompileOptions(&nOpt);
if( N>=0 && N<nOpt ){
return azCompileOpt[N];
}
return 0;
}
#endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
/************** End of main.c ************************************************/
/************** Begin file notify.c ******************************************/
/*
** 2009 March 3
**
** 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 file contains the implementation of the sqlite3_unlock_notify()
** API method and its associated functionality.
*/
/* #include "sqliteInt.h" */
/* #include "btreeInt.h" */
/* Omit this entire file if SQLITE_ENABLE_UNLOCK_NOTIFY is not defined. */
#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
/*
** Public interfaces:
**
** sqlite3ConnectionBlocked()
** sqlite3ConnectionUnlocked()
** sqlite3ConnectionClosed()
** sqlite3_unlock_notify()
*/
#define assertMutexHeld() \
assert( sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER)) )
/*
** Head of a linked list of all sqlite3 objects created by this process
** for which either sqlite3.pBlockingConnection or sqlite3.pUnlockConnection
** is not NULL. This variable may only accessed while the STATIC_MASTER
** mutex is held.
*/
static sqlite3 *SQLITE_WSD sqlite3BlockedList = 0;
#ifndef NDEBUG
/*
** This function is a complex assert() that verifies the following
** properties of the blocked connections list:
**
** 1) Each entry in the list has a non-NULL value for either
** pUnlockConnection or pBlockingConnection, or both.
**
** 2) All entries in the list that share a common value for
** xUnlockNotify are grouped together.
**
** 3) If the argument db is not NULL, then none of the entries in the
** blocked connections list have pUnlockConnection or pBlockingConnection
** set to db. This is used when closing connection db.
*/
static void checkListProperties(sqlite3 *db){
sqlite3 *p;
for(p=sqlite3BlockedList; p; p=p->pNextBlocked){
int seen = 0;
sqlite3 *p2;
/* Verify property (1) */
assert( p->pUnlockConnection || p->pBlockingConnection );
/* Verify property (2) */
for(p2=sqlite3BlockedList; p2!=p; p2=p2->pNextBlocked){
if( p2->xUnlockNotify==p->xUnlockNotify ) seen = 1;
assert( p2->xUnlockNotify==p->xUnlockNotify || !seen );
assert( db==0 || p->pUnlockConnection!=db );
assert( db==0 || p->pBlockingConnection!=db );
}
}
}
#else
# define checkListProperties(x)
#endif
/*
** Remove connection db from the blocked connections list. If connection
** db is not currently a part of the list, this function is a no-op.
*/
static void removeFromBlockedList(sqlite3 *db){
sqlite3 **pp;
assertMutexHeld();
for(pp=&sqlite3BlockedList; *pp; pp = &(*pp)->pNextBlocked){
if( *pp==db ){
*pp = (*pp)->pNextBlocked;
break;
}
}
}
/*
** Add connection db to the blocked connections list. It is assumed
** that it is not already a part of the list.
*/
static void addToBlockedList(sqlite3 *db){
sqlite3 **pp;
assertMutexHeld();
for(
pp=&sqlite3BlockedList;
*pp && (*pp)->xUnlockNotify!=db->xUnlockNotify;
pp=&(*pp)->pNextBlocked
);
db->pNextBlocked = *pp;
*pp = db;
}
/*
** Obtain the STATIC_MASTER mutex.
*/
static void enterMutex(void){
sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
checkListProperties(0);
}
/*
** Release the STATIC_MASTER mutex.
*/
static void leaveMutex(void){
assertMutexHeld();
checkListProperties(0);
sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
}
/*
** Register an unlock-notify callback.
**
** This is called after connection "db" has attempted some operation
** but has received an SQLITE_LOCKED error because another connection
** (call it pOther) in the same process was busy using the same shared
** cache. pOther is found by looking at db->pBlockingConnection.
**
** If there is no blocking connection, the callback is invoked immediately,
** before this routine returns.
**
** If pOther is already blocked on db, then report SQLITE_LOCKED, to indicate
** a deadlock.
**
** Otherwise, make arrangements to invoke xNotify when pOther drops
** its locks.
**
** Each call to this routine overrides any prior callbacks registered
** on the same "db". If xNotify==0 then any prior callbacks are immediately
** cancelled.
*/
SQLITE_API int sqlite3_unlock_notify(
sqlite3 *db,
void (*xNotify)(void **, int),
void *pArg
){
int rc = SQLITE_OK;
sqlite3_mutex_enter(db->mutex);
enterMutex();
if( xNotify==0 ){
removeFromBlockedList(db);
db->pBlockingConnection = 0;
db->pUnlockConnection = 0;
db->xUnlockNotify = 0;
db->pUnlockArg = 0;
}else if( 0==db->pBlockingConnection ){
/* The blocking transaction has been concluded. Or there never was a
** blocking transaction. In either case, invoke the notify callback
** immediately.
*/
xNotify(&pArg, 1);
}else{
sqlite3 *p;
for(p=db->pBlockingConnection; p && p!=db; p=p->pUnlockConnection){}
if( p ){
rc = SQLITE_LOCKED; /* Deadlock detected. */
}else{
db->pUnlockConnection = db->pBlockingConnection;
db->xUnlockNotify = xNotify;
db->pUnlockArg = pArg;
removeFromBlockedList(db);
addToBlockedList(db);
}
}
leaveMutex();
assert( !db->mallocFailed );
sqlite3ErrorWithMsg(db, rc, (rc?"database is deadlocked":0));
sqlite3_mutex_leave(db->mutex);
return rc;
}
/*
** This function is called while stepping or preparing a statement
** associated with connection db. The operation will return SQLITE_LOCKED
** to the user because it requires a lock that will not be available
** until connection pBlocker concludes its current transaction.
*/
SQLITE_PRIVATE void sqlite3ConnectionBlocked(sqlite3 *db, sqlite3 *pBlocker){
enterMutex();
if( db->pBlockingConnection==0 && db->pUnlockConnection==0 ){
addToBlockedList(db);
}
db->pBlockingConnection = pBlocker;
leaveMutex();
}
/*
** This function is called when
** the transaction opened by database db has just finished. Locks held
** by database connection db have been released.
**
** This function loops through each entry in the blocked connections
** list and does the following:
**
** 1) If the sqlite3.pBlockingConnection member of a list entry is
** set to db, then set pBlockingConnection=0.
**
** 2) If the sqlite3.pUnlockConnection member of a list entry is
** set to db, then invoke the configured unlock-notify callback and
** set pUnlockConnection=0.
**
** 3) If the two steps above mean that pBlockingConnection==0 and
** pUnlockConnection==0, remove the entry from the blocked connections
** list.
*/
SQLITE_PRIVATE void sqlite3ConnectionUnlocked(sqlite3 *db){
void (*xUnlockNotify)(void **, int) = 0; /* Unlock-notify cb to invoke */
int nArg = 0; /* Number of entries in aArg[] */
sqlite3 **pp; /* Iterator variable */
void **aArg; /* Arguments to the unlock callback */
void **aDyn = 0; /* Dynamically allocated space for aArg[] */
void *aStatic[16]; /* Starter space for aArg[]. No malloc required */
aArg = aStatic;
enterMutex(); /* Enter STATIC_MASTER mutex */
/* This loop runs once for each entry in the blocked-connections list. */
for(pp=&sqlite3BlockedList; *pp; /* no-op */ ){
sqlite3 *p = *pp;
/* Step 1. */
if( p->pBlockingConnection==db ){
p->pBlockingConnection = 0;
}
/* Step 2. */
if( p->pUnlockConnection==db ){
assert( p->xUnlockNotify );
if( p->xUnlockNotify!=xUnlockNotify && nArg!=0 ){
xUnlockNotify(aArg, nArg);
nArg = 0;
}
sqlite3BeginBenignMalloc();
assert( aArg==aDyn || (aDyn==0 && aArg==aStatic) );
assert( nArg<=(int)ArraySize(aStatic) || aArg==aDyn );
if( (!aDyn && nArg==(int)ArraySize(aStatic))
|| (aDyn && nArg==(int)(sqlite3MallocSize(aDyn)/sizeof(void*)))
){
/* The aArg[] array needs to grow. */
void **pNew = (void **)sqlite3Malloc(nArg*sizeof(void *)*2);
if( pNew ){
memcpy(pNew, aArg, nArg*sizeof(void *));
sqlite3_free(aDyn);
aDyn = aArg = pNew;
}else{
/* This occurs when the array of context pointers that need to
** be passed to the unlock-notify callback is larger than the
** aStatic[] array allocated on the stack and the attempt to
** allocate a larger array from the heap has failed.
**
** This is a difficult situation to handle. Returning an error
** code to the caller is insufficient, as even if an error code
** is returned the transaction on connection db will still be
** closed and the unlock-notify callbacks on blocked connections
** will go unissued. This might cause the application to wait
** indefinitely for an unlock-notify callback that will never
** arrive.
**
** Instead, invoke the unlock-notify callback with the context
** array already accumulated. We can then clear the array and
** begin accumulating any further context pointers without
** requiring any dynamic allocation. This is sub-optimal because
** it means that instead of one callback with a large array of
** context pointers the application will receive two or more
** callbacks with smaller arrays of context pointers, which will
** reduce the applications ability to prioritize multiple
** connections. But it is the best that can be done under the
** circumstances.
*/
xUnlockNotify(aArg, nArg);
nArg = 0;
}
}
sqlite3EndBenignMalloc();
aArg[nArg++] = p->pUnlockArg;
xUnlockNotify = p->xUnlockNotify;
p->pUnlockConnection = 0;
p->xUnlockNotify = 0;
p->pUnlockArg = 0;
}
/* Step 3. */
if( p->pBlockingConnection==0 && p->pUnlockConnection==0 ){
/* Remove connection p from the blocked connections list. */
*pp = p->pNextBlocked;
p->pNextBlocked = 0;
}else{
pp = &p->pNextBlocked;
}
}
if( nArg!=0 ){
xUnlockNotify(aArg, nArg);
}
sqlite3_free(aDyn);
leaveMutex(); /* Leave STATIC_MASTER mutex */
}
/*
** This is called when the database connection passed as an argument is
** being closed. The connection is removed from the blocked list.
*/
SQLITE_PRIVATE void sqlite3ConnectionClosed(sqlite3 *db){
sqlite3ConnectionUnlocked(db);
enterMutex();
removeFromBlockedList(db);
checkListProperties(db);
leaveMutex();
}
#endif
/************** End of notify.c **********************************************/
/************** Begin file fts3.c ********************************************/
/*
** 2006 Oct 10
**
** 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 is an SQLite module implementing full-text search.
*/
/*
** The code in this file is only compiled if:
**
** * The FTS3 module is being built as an extension
** (in which case SQLITE_CORE is not defined), or
**
** * The FTS3 module is being built into the core of
** SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/
/* The full-text index is stored in a series of b+tree (-like)
** structures called segments which map terms to doclists. The
** structures are like b+trees in layout, but are constructed from the
** bottom up in optimal fashion and are not updatable. Since trees
** are built from the bottom up, things will be described from the
** bottom up.
**
**
**** Varints ****
** The basic unit of encoding is a variable-length integer called a
** varint. We encode variable-length integers in little-endian order
** using seven bits * per byte as follows:
**
** KEY:
** A = 0xxxxxxx 7 bits of data and one flag bit
** B = 1xxxxxxx 7 bits of data and one flag bit
**
** 7 bits - A
** 14 bits - BA
** 21 bits - BBA
** and so on.
**
** This is similar in concept to how sqlite encodes "varints" but
** the encoding is not the same. SQLite varints are big-endian
** are are limited to 9 bytes in length whereas FTS3 varints are
** little-endian and can be up to 10 bytes in length (in theory).
**
** Example encodings:
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