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Overview
Comment:Documentation enhancements for sqlite3_update_hook(), sqlite3_commit_hook(), and the various incremental blob I/O routines. No changes to code. (CVS 6639)
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: e8ca932d8c7e1753c159041499355724d3e78b35
User & Date: drh 2009-05-14 22:37:48
Context
2009-05-15
14:41
Re-enable file locking in async4.test. (CVS 6640) check-in: f7098187 user: danielk1977 tags: trunk
2009-05-14
22:37
Documentation enhancements for sqlite3_update_hook(), sqlite3_commit_hook(), and the various incremental blob I/O routines. No changes to code. (CVS 6639) check-in: e8ca932d user: drh tags: trunk
19:26
Change the sqlite3_backup_finish() interface so that calling it with a NULL pointer is a harmless no-op. One other change to backup.c to facilitate full coverage testing. (CVS 6638) check-in: 06bc8917 user: drh tags: trunk
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Changes to src/sqlite.h.in.

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** on how SQLite interfaces are suppose to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
**
** @(#) $Id: sqlite.h.in,v 1.449 2009/05/14 03:21:28 shane Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.
................................................................................
*/
sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);

/*
** CAPI3REF: Commit And Rollback Notification Callbacks {H12950} <S60400>
**
** The sqlite3_commit_hook() interface registers a callback
** function to be invoked whenever a transaction is committed.
** Any callback set by a previous call to sqlite3_commit_hook()
** for the same database connection is overridden.
** The sqlite3_rollback_hook() interface registers a callback
** function to be invoked whenever a transaction is committed.
** Any callback set by a previous call to sqlite3_commit_hook()
** for the same database connection is overridden.
** The pArg argument is passed through to the callback.
** If the callback on a commit hook function returns non-zero,
** then the commit is converted into a rollback.
**
** If another function was previously registered, its
................................................................................
** completion of the [sqlite3_step()] call that triggered the commit
** or rollback hook in the first place.
** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
** database connections for the meaning of "modify" in this paragraph.
**
** Registering a NULL function disables the callback.
**






** For the purposes of this API, a transaction is said to have been
** rolled back if an explicit "ROLLBACK" statement is executed, or
** an error or constraint causes an implicit rollback to occur.
** The rollback callback is not invoked if a transaction is
** automatically rolled back because the database connection is closed.
** The rollback callback is not invoked if a transaction is
** rolled back because a commit callback returned non-zero.
** <todo> Check on this </todo>


**
** Requirements:
** [H12951] [H12952] [H12953] [H12954] [H12955]
** [H12961] [H12962] [H12963] [H12964]
*/
void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
................................................................................
** The third and fourth arguments to the callback contain pointers to the
** database and table name containing the affected row.
** The final callback parameter is the [rowid] of the row.
** In the case of an update, this is the [rowid] after the update takes place.
**
** The update hook is not invoked when internal system tables are
** modified (i.e. sqlite_master and sqlite_sequence).







**
** The update hook implementation must not do anything that will modify
** the database connection that invoked the update hook.  Any actions
** to modify the database connection must be deferred until after the
** completion of the [sqlite3_step()] call that triggered the update hook.
** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
** database connections for the meaning of "modify" in this paragraph.
**
** If another function was previously registered, its pArg value
** is returned.  Otherwise NULL is returned.



**
** Requirements:
** [H12971] [H12973] [H12975] [H12977] [H12979] [H12981] [H12983] [H12986]
*/
void *sqlite3_update_hook(
  sqlite3*, 
  void(*)(void *,int ,char const *,char const *,sqlite3_int64),
................................................................................
** Note that the database name is not the filename that contains
** the database but rather the symbolic name of the database that
** is assigned when the database is connected using [ATTACH].
** For the main database file, the database name is "main".
** For TEMP tables, the database name is "temp".
**
** On success, [SQLITE_OK] is returned and the new [BLOB handle] is written
** to *ppBlob. Otherwise an [error code] is returned and any value written
** to *ppBlob should not be used by the caller.
** This function sets the [database connection] error code and message
** accessible via [sqlite3_errcode()] and [sqlite3_errmsg()].



**
** If the row that a BLOB handle points to is modified by an
** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
** then the BLOB handle is marked as "expired".
** This is true if any column of the row is changed, even a column
** other than the one the BLOB handle is open on.
** Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
** a expired BLOB handle fail with an return code of [SQLITE_ABORT].
** Changes written into a BLOB prior to the BLOB expiring are not
** rollback by the expiration of the BLOB.  Such changes will eventually
** commit if the transaction continues to completion.













**
** Requirements:
** [H17813] [H17814] [H17816] [H17819] [H17821] [H17824]
*/
int sqlite3_blob_open(
  sqlite3*,
  const char *zDb,
................................................................................
**
** Closes an open [BLOB handle].
**
** Closing a BLOB shall cause the current transaction to commit
** if there are no other BLOBs, no pending prepared statements, and the
** database connection is in [autocommit mode].
** If any writes were made to the BLOB, they might be held in cache
** until the close operation if they will fit. {END}
**
** Closing the BLOB often forces the changes
** out to disk and so if any I/O errors occur, they will likely occur
** at the time when the BLOB is closed.  {H17833} Any errors that occur during
** closing are reported as a non-zero return value.
**
** The BLOB is closed unconditionally.  Even if this routine returns
** an error code, the BLOB is still closed.



**
** Requirements:
** [H17833] [H17836] [H17839]
*/
int sqlite3_blob_close(sqlite3_blob *);

/*
** CAPI3REF: Return The Size Of An Open BLOB {H17840} <S30230>
**
** Returns the size in bytes of the BLOB accessible via the open
** []BLOB handle] in its only argument.







**
** Requirements:
** [H17843]
*/
int sqlite3_blob_bytes(sqlite3_blob *);

/*
................................................................................
** This function is used to read data from an open [BLOB handle] into a
** caller-supplied buffer. N bytes of data are copied into buffer Z
** from the open BLOB, starting at offset iOffset.
**
** If offset iOffset is less than N bytes from the end of the BLOB,
** [SQLITE_ERROR] is returned and no data is read.  If N or iOffset is
** less than zero, [SQLITE_ERROR] is returned and no data is read.


**
** An attempt to read from an expired [BLOB handle] fails with an
** error code of [SQLITE_ABORT].
**
** On success, SQLITE_OK is returned.
** Otherwise, an [error code] or an [extended error code] is returned.







**
** Requirements:
** [H17853] [H17856] [H17859] [H17862] [H17863] [H17865] [H17868]
*/
int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);

/*
................................................................................
** this function returns [SQLITE_READONLY].
**
** This function may only modify the contents of the BLOB; it is
** not possible to increase the size of a BLOB using this API.
** If offset iOffset is less than N bytes from the end of the BLOB,
** [SQLITE_ERROR] is returned and no data is written.  If N is
** less than zero [SQLITE_ERROR] is returned and no data is written.


**
** An attempt to write to an expired [BLOB handle] fails with an
** error code of [SQLITE_ABORT].  Writes to the BLOB that occurred
** before the [BLOB handle] expired are not rolled back by the
** expiration of the handle, though of course those changes might
** have been overwritten by the statement that expired the BLOB handle
** or by other independent statements.
**
** On success, SQLITE_OK is returned.
** Otherwise, an  [error code] or an [extended error code] is returned.







**
** Requirements:
** [H17873] [H17874] [H17875] [H17876] [H17877] [H17879] [H17882] [H17885]
** [H17888]
*/
int sqlite3_blob_write(sqlite3_blob *, const void *z, int n, int iOffset);








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** on how SQLite interfaces are suppose to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
**
** @(#) $Id: sqlite.h.in,v 1.450 2009/05/14 22:37:48 drh Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.
................................................................................
*/
sqlite3_stmt *sqlite3_next_stmt(sqlite3 *pDb, sqlite3_stmt *pStmt);

/*
** CAPI3REF: Commit And Rollback Notification Callbacks {H12950} <S60400>
**
** The sqlite3_commit_hook() interface registers a callback
** function to be invoked whenever a transaction is [COMMIT | committed].
** Any callback set by a previous call to sqlite3_commit_hook()
** for the same database connection is overridden.
** The sqlite3_rollback_hook() interface registers a callback
** function to be invoked whenever a transaction is [ROLLBACK | rolled back].
** Any callback set by a previous call to sqlite3_commit_hook()
** for the same database connection is overridden.
** The pArg argument is passed through to the callback.
** If the callback on a commit hook function returns non-zero,
** then the commit is converted into a rollback.
**
** If another function was previously registered, its
................................................................................
** completion of the [sqlite3_step()] call that triggered the commit
** or rollback hook in the first place.
** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
** database connections for the meaning of "modify" in this paragraph.
**
** Registering a NULL function disables the callback.
**
** When the commit hook callback routine returns zero, the [COMMIT]
** operation is allowed to continue normally.  If the commit hook
** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].
** The rollback hook is invoked on a rollback that results from a commit
** hook returning non-zero, just as it would be with any other rollback.
**
** For the purposes of this API, a transaction is said to have been
** rolled back if an explicit "ROLLBACK" statement is executed, or
** an error or constraint causes an implicit rollback to occur.
** The rollback callback is not invoked if a transaction is
** automatically rolled back because the database connection is closed.
** The rollback callback is not invoked if a transaction is
** rolled back because a commit callback returned non-zero.
** <todo> Check on this </todo>
**
** See also the [sqlite3_update_hook()] interface.
**
** Requirements:
** [H12951] [H12952] [H12953] [H12954] [H12955]
** [H12961] [H12962] [H12963] [H12964]
*/
void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);
................................................................................
** The third and fourth arguments to the callback contain pointers to the
** database and table name containing the affected row.
** The final callback parameter is the [rowid] of the row.
** In the case of an update, this is the [rowid] after the update takes place.
**
** The update hook is not invoked when internal system tables are
** modified (i.e. sqlite_master and sqlite_sequence).
**
** In the current implementation, the update hook
** is not invoked when duplication rows are deleted because of an
** [ON CONFLICT | ON CONFLICT REPLACE] clause.  Nor is the update hook
** invoked when rows are deleted using the [truncate optimization].
** The exceptions defined in this paragraph might change in a future
** release of SQLite.
**
** The update hook implementation must not do anything that will modify
** the database connection that invoked the update hook.  Any actions
** to modify the database connection must be deferred until after the
** completion of the [sqlite3_step()] call that triggered the update hook.
** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
** database connections for the meaning of "modify" in this paragraph.
**
** If another function was previously registered, its pArg value
** is returned.  Otherwise NULL is returned.
**
** See also the [sqlite3_commit_hook()] and [sqlite3_rollback_hook()]
** interfaces.
**
** Requirements:
** [H12971] [H12973] [H12975] [H12977] [H12979] [H12981] [H12983] [H12986]
*/
void *sqlite3_update_hook(
  sqlite3*, 
  void(*)(void *,int ,char const *,char const *,sqlite3_int64),
................................................................................
** Note that the database name is not the filename that contains
** the database but rather the symbolic name of the database that
** is assigned when the database is connected using [ATTACH].
** For the main database file, the database name is "main".
** For TEMP tables, the database name is "temp".
**
** On success, [SQLITE_OK] is returned and the new [BLOB handle] is written
** to *ppBlob. Otherwise an [error code] is returned and *ppBlob is set
** to be a null pointer.
** This function sets the [database connection] error code and message
** accessible via [sqlite3_errcode()] and [sqlite3_errmsg()] and related
** functions.  Note that the *ppBlob variable is always initialized in a
** way that makes it safe to invoke [sqlite3_blob_close()] on *ppBlob
** regardless of the success or failure of this routine.
**
** If the row that a BLOB handle points to is modified by an
** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
** then the BLOB handle is marked as "expired".
** This is true if any column of the row is changed, even a column
** other than the one the BLOB handle is open on.
** Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
** a expired BLOB handle fail with an return code of [SQLITE_ABORT].
** Changes written into a BLOB prior to the BLOB expiring are not
** rollback by the expiration of the BLOB.  Such changes will eventually
** commit if the transaction continues to completion.
**
** Use the [sqlite3_blob_bytes()] interface to determine the size of
** the opened blob.  The size of a blob may not be changed by this
** underface.  Use the [UPDATE] SQL command to change the size of a
** blob.
**
** The [sqlite3_bind_zeroblob()] and [sqlite3_result_zeroblob()] interfaces
** and the built-in [zeroblob] SQL function can be used, if desired,
** to create an empty, zero-filled blob in which to read or write using
** this interface.
**
** To avoid a resource leak, every open [BLOB handle] should eventually
** be released by a call to [sqlite3_blob_close()].
**
** Requirements:
** [H17813] [H17814] [H17816] [H17819] [H17821] [H17824]
*/
int sqlite3_blob_open(
  sqlite3*,
  const char *zDb,
................................................................................
**
** Closes an open [BLOB handle].
**
** Closing a BLOB shall cause the current transaction to commit
** if there are no other BLOBs, no pending prepared statements, and the
** database connection is in [autocommit mode].
** If any writes were made to the BLOB, they might be held in cache
** until the close operation if they will fit.
**
** Closing the BLOB often forces the changes
** out to disk and so if any I/O errors occur, they will likely occur
** at the time when the BLOB is closed.  Any errors that occur during
** closing are reported as a non-zero return value.
**
** The BLOB is closed unconditionally.  Even if this routine returns
** an error code, the BLOB is still closed.
**
** Calling this routine with a null pointer (which as would be returned
** by failed call to [sqlite3_blob_open()]) is a harmless no-op.
**
** Requirements:
** [H17833] [H17836] [H17839]
*/
int sqlite3_blob_close(sqlite3_blob *);

/*
** CAPI3REF: Return The Size Of An Open BLOB {H17840} <S30230>
**
** Returns the size in bytes of the BLOB accessible via the 
** successfully opened [BLOB handle] in its only argument.  The
** incremental blob I/O routines can only read or overwriting existing
** blob content; they cannot change the size of a blob.
**
** This routine only works on a [BLOB handle] which has been created
** by a prior successful call to [sqlite3_blob_open()] and which has not
** been closed by [sqlite3_blob_close()].  Passing any other pointer in
** to this routine results in undefined and probably undesirable behavior.
**
** Requirements:
** [H17843]
*/
int sqlite3_blob_bytes(sqlite3_blob *);

/*
................................................................................
** This function is used to read data from an open [BLOB handle] into a
** caller-supplied buffer. N bytes of data are copied into buffer Z
** from the open BLOB, starting at offset iOffset.
**
** If offset iOffset is less than N bytes from the end of the BLOB,
** [SQLITE_ERROR] is returned and no data is read.  If N or iOffset is
** less than zero, [SQLITE_ERROR] is returned and no data is read.
** The size of the blob (and hence the maximum value of N+iOffset)
** can be determined using the [sqlite3_blob_bytes()] interface.
**
** An attempt to read from an expired [BLOB handle] fails with an
** error code of [SQLITE_ABORT].
**
** On success, SQLITE_OK is returned.
** Otherwise, an [error code] or an [extended error code] is returned.
**
** This routine only works on a [BLOB handle] which has been created
** by a prior successful call to [sqlite3_blob_open()] and which has not
** been closed by [sqlite3_blob_close()].  Passing any other pointer in
** to this routine results in undefined and probably undesirable behavior.
**
** See also: [sqlite3_blob_write()].
**
** Requirements:
** [H17853] [H17856] [H17859] [H17862] [H17863] [H17865] [H17868]
*/
int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);

/*
................................................................................
** this function returns [SQLITE_READONLY].
**
** This function may only modify the contents of the BLOB; it is
** not possible to increase the size of a BLOB using this API.
** If offset iOffset is less than N bytes from the end of the BLOB,
** [SQLITE_ERROR] is returned and no data is written.  If N is
** less than zero [SQLITE_ERROR] is returned and no data is written.
** The size of the BLOB (and hence the maximum value of N+iOffset)
** can be determined using the [sqlite3_blob_bytes()] interface.
**
** An attempt to write to an expired [BLOB handle] fails with an
** error code of [SQLITE_ABORT].  Writes to the BLOB that occurred
** before the [BLOB handle] expired are not rolled back by the
** expiration of the handle, though of course those changes might
** have been overwritten by the statement that expired the BLOB handle
** or by other independent statements.
**
** On success, SQLITE_OK is returned.
** Otherwise, an  [error code] or an [extended error code] is returned.
**
** This routine only works on a [BLOB handle] which has been created
** by a prior successful call to [sqlite3_blob_open()] and which has not
** been closed by [sqlite3_blob_close()].  Passing any other pointer in
** to this routine results in undefined and probably undesirable behavior.
**
** See also: [sqlite3_blob_read()].
**
** Requirements:
** [H17873] [H17874] [H17875] [H17876] [H17877] [H17879] [H17882] [H17885]
** [H17888]
*/
int sqlite3_blob_write(sqlite3_blob *, const void *z, int n, int iOffset);