4d26d585d6
FossilOrigin-Name: 1965b85318c1fac62fae9691059021b298c17dde
683 lines
23 KiB
C
683 lines
23 KiB
C
/*
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** 2009 January 28
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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*************************************************************************
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** This file contains the implementation of the sqlite3_backup_XXX()
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** API functions and the related features.
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*/
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#include "sqliteInt.h"
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#include "btreeInt.h"
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/* Macro to find the minimum of two numeric values.
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*/
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#ifndef MIN
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# define MIN(x,y) ((x)<(y)?(x):(y))
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#endif
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/*
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** Structure allocated for each backup operation.
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*/
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struct sqlite3_backup {
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sqlite3* pDestDb; /* Destination database handle */
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Btree *pDest; /* Destination b-tree file */
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u32 iDestSchema; /* Original schema cookie in destination */
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int bDestLocked; /* True once a write-transaction is open on pDest */
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Pgno iNext; /* Page number of the next source page to copy */
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sqlite3* pSrcDb; /* Source database handle */
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Btree *pSrc; /* Source b-tree file */
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int rc; /* Backup process error code */
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/* These two variables are set by every call to backup_step(). They are
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** read by calls to backup_remaining() and backup_pagecount().
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*/
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Pgno nRemaining; /* Number of pages left to copy */
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Pgno nPagecount; /* Total number of pages to copy */
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int isAttached; /* True once backup has been registered with pager */
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sqlite3_backup *pNext; /* Next backup associated with source pager */
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};
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/*
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** THREAD SAFETY NOTES:
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**
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** Once it has been created using backup_init(), a single sqlite3_backup
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** structure may be accessed via two groups of thread-safe entry points:
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**
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** * Via the sqlite3_backup_XXX() API function backup_step() and
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** backup_finish(). Both these functions obtain the source database
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** handle mutex and the mutex associated with the source BtShared
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** structure, in that order.
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**
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** * Via the BackupUpdate() and BackupRestart() functions, which are
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** invoked by the pager layer to report various state changes in
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** the page cache associated with the source database. The mutex
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** associated with the source database BtShared structure will always
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** be held when either of these functions are invoked.
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**
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** The other sqlite3_backup_XXX() API functions, backup_remaining() and
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** backup_pagecount() are not thread-safe functions. If they are called
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** while some other thread is calling backup_step() or backup_finish(),
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** the values returned may be invalid. There is no way for a call to
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** BackupUpdate() or BackupRestart() to interfere with backup_remaining()
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** or backup_pagecount().
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**
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** Depending on the SQLite configuration, the database handles and/or
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** the Btree objects may have their own mutexes that require locking.
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** Non-sharable Btrees (in-memory databases for example), do not have
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** associated mutexes.
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*/
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/*
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** Return a pointer corresponding to database zDb (i.e. "main", "temp")
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** in connection handle pDb. If such a database cannot be found, return
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** a NULL pointer and write an error message to pErrorDb.
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**
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** If the "temp" database is requested, it may need to be opened by this
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** function. If an error occurs while doing so, return 0 and write an
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** error message to pErrorDb.
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*/
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static Btree *findBtree(sqlite3 *pErrorDb, sqlite3 *pDb, const char *zDb){
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int i = sqlite3FindDbName(pDb, zDb);
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if( i==1 ){
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Parse *pParse;
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int rc = 0;
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pParse = sqlite3StackAllocZero(pErrorDb, sizeof(*pParse));
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if( pParse==0 ){
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sqlite3Error(pErrorDb, SQLITE_NOMEM, "out of memory");
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rc = SQLITE_NOMEM;
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}else{
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pParse->db = pDb;
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if( sqlite3OpenTempDatabase(pParse) ){
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sqlite3Error(pErrorDb, pParse->rc, "%s", pParse->zErrMsg);
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rc = SQLITE_ERROR;
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}
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sqlite3DbFree(pErrorDb, pParse->zErrMsg);
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sqlite3StackFree(pErrorDb, pParse);
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}
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if( rc ){
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return 0;
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}
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}
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if( i<0 ){
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sqlite3Error(pErrorDb, SQLITE_ERROR, "unknown database %s", zDb);
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return 0;
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}
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return pDb->aDb[i].pBt;
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}
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/*
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** Attempt to set the page size of the destination to match the page size
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** of the source.
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*/
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static int setDestPgsz(sqlite3_backup *p){
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int rc;
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rc = sqlite3BtreeSetPageSize(p->pDest,sqlite3BtreeGetPageSize(p->pSrc),-1,0);
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return rc;
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}
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/*
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** Create an sqlite3_backup process to copy the contents of zSrcDb from
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** connection handle pSrcDb to zDestDb in pDestDb. If successful, return
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** a pointer to the new sqlite3_backup object.
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**
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** If an error occurs, NULL is returned and an error code and error message
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** stored in database handle pDestDb.
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*/
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sqlite3_backup *sqlite3_backup_init(
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sqlite3* pDestDb, /* Database to write to */
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const char *zDestDb, /* Name of database within pDestDb */
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sqlite3* pSrcDb, /* Database connection to read from */
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const char *zSrcDb /* Name of database within pSrcDb */
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){
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sqlite3_backup *p; /* Value to return */
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/* Lock the source database handle. The destination database
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** handle is not locked in this routine, but it is locked in
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** sqlite3_backup_step(). The user is required to ensure that no
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** other thread accesses the destination handle for the duration
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** of the backup operation. Any attempt to use the destination
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** database connection while a backup is in progress may cause
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** a malfunction or a deadlock.
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*/
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sqlite3_mutex_enter(pSrcDb->mutex);
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sqlite3_mutex_enter(pDestDb->mutex);
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if( pSrcDb==pDestDb ){
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sqlite3Error(
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pDestDb, SQLITE_ERROR, "source and destination must be distinct"
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);
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p = 0;
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}else {
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/* Allocate space for a new sqlite3_backup object...
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** EVIDENCE-OF: R-64852-21591 The sqlite3_backup object is created by a
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** call to sqlite3_backup_init() and is destroyed by a call to
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** sqlite3_backup_finish(). */
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p = (sqlite3_backup *)sqlite3_malloc(sizeof(sqlite3_backup));
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if( !p ){
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sqlite3Error(pDestDb, SQLITE_NOMEM, 0);
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}
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}
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/* If the allocation succeeded, populate the new object. */
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if( p ){
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memset(p, 0, sizeof(sqlite3_backup));
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p->pSrc = findBtree(pDestDb, pSrcDb, zSrcDb);
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p->pDest = findBtree(pDestDb, pDestDb, zDestDb);
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p->pDestDb = pDestDb;
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p->pSrcDb = pSrcDb;
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p->iNext = 1;
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p->isAttached = 0;
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if( 0==p->pSrc || 0==p->pDest || setDestPgsz(p)==SQLITE_NOMEM ){
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/* One (or both) of the named databases did not exist or an OOM
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** error was hit. The error has already been written into the
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** pDestDb handle. All that is left to do here is free the
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** sqlite3_backup structure.
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*/
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sqlite3_free(p);
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p = 0;
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}
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}
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if( p ){
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p->pSrc->nBackup++;
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}
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sqlite3_mutex_leave(pDestDb->mutex);
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sqlite3_mutex_leave(pSrcDb->mutex);
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return p;
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}
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/*
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** Argument rc is an SQLite error code. Return true if this error is
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** considered fatal if encountered during a backup operation. All errors
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** are considered fatal except for SQLITE_BUSY and SQLITE_LOCKED.
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*/
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static int isFatalError(int rc){
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return (rc!=SQLITE_OK && rc!=SQLITE_BUSY && ALWAYS(rc!=SQLITE_LOCKED));
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}
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/*
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** Parameter zSrcData points to a buffer containing the data for
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** page iSrcPg from the source database. Copy this data into the
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** destination database.
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*/
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static int backupOnePage(sqlite3_backup *p, Pgno iSrcPg, const u8 *zSrcData){
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Pager * const pDestPager = sqlite3BtreePager(p->pDest);
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const int nSrcPgsz = sqlite3BtreeGetPageSize(p->pSrc);
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int nDestPgsz = sqlite3BtreeGetPageSize(p->pDest);
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const int nCopy = MIN(nSrcPgsz, nDestPgsz);
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const i64 iEnd = (i64)iSrcPg*(i64)nSrcPgsz;
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int rc = SQLITE_OK;
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i64 iOff;
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assert( p->bDestLocked );
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assert( !isFatalError(p->rc) );
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assert( iSrcPg!=PENDING_BYTE_PAGE(p->pSrc->pBt) );
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assert( zSrcData );
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/* Catch the case where the destination is an in-memory database and the
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** page sizes of the source and destination differ.
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*/
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if( nSrcPgsz!=nDestPgsz && sqlite3PagerIsMemdb(pDestPager) ){
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rc = SQLITE_READONLY;
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}
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#ifdef SQLITE_HAS_CODEC
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/* Backup is not possible if the page size of the destination is changing
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** a a codec is in use.
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*/
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if( nSrcPgsz!=nDestPgsz && sqlite3PagerGetCodec(pDestPager)!=0 ){
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rc = SQLITE_READONLY;
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}
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#endif
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/* This loop runs once for each destination page spanned by the source
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** page. For each iteration, variable iOff is set to the byte offset
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** of the destination page.
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*/
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for(iOff=iEnd-(i64)nSrcPgsz; rc==SQLITE_OK && iOff<iEnd; iOff+=nDestPgsz){
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DbPage *pDestPg = 0;
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Pgno iDest = (Pgno)(iOff/nDestPgsz)+1;
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if( iDest==PENDING_BYTE_PAGE(p->pDest->pBt) ) continue;
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if( SQLITE_OK==(rc = sqlite3PagerGet(pDestPager, iDest, &pDestPg))
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&& SQLITE_OK==(rc = sqlite3PagerWrite(pDestPg))
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){
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const u8 *zIn = &zSrcData[iOff%nSrcPgsz];
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u8 *zDestData = sqlite3PagerGetData(pDestPg);
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u8 *zOut = &zDestData[iOff%nDestPgsz];
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/* Copy the data from the source page into the destination page.
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** Then clear the Btree layer MemPage.isInit flag. Both this module
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** and the pager code use this trick (clearing the first byte
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** of the page 'extra' space to invalidate the Btree layers
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** cached parse of the page). MemPage.isInit is marked
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** "MUST BE FIRST" for this purpose.
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*/
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memcpy(zOut, zIn, nCopy);
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((u8 *)sqlite3PagerGetExtra(pDestPg))[0] = 0;
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}
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sqlite3PagerUnref(pDestPg);
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}
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return rc;
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}
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/*
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** If pFile is currently larger than iSize bytes, then truncate it to
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** exactly iSize bytes. If pFile is not larger than iSize bytes, then
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** this function is a no-op.
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**
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** Return SQLITE_OK if everything is successful, or an SQLite error
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** code if an error occurs.
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*/
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static int backupTruncateFile(sqlite3_file *pFile, i64 iSize){
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i64 iCurrent;
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int rc = sqlite3OsFileSize(pFile, &iCurrent);
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if( rc==SQLITE_OK && iCurrent>iSize ){
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rc = sqlite3OsTruncate(pFile, iSize);
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}
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return rc;
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}
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/*
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** Register this backup object with the associated source pager for
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** callbacks when pages are changed or the cache invalidated.
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*/
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static void attachBackupObject(sqlite3_backup *p){
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sqlite3_backup **pp;
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assert( sqlite3BtreeHoldsMutex(p->pSrc) );
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pp = sqlite3PagerBackupPtr(sqlite3BtreePager(p->pSrc));
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p->pNext = *pp;
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*pp = p;
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p->isAttached = 1;
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}
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/*
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** Copy nPage pages from the source b-tree to the destination.
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*/
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int sqlite3_backup_step(sqlite3_backup *p, int nPage){
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int rc;
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int destMode; /* Destination journal mode */
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int pgszSrc = 0; /* Source page size */
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int pgszDest = 0; /* Destination page size */
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sqlite3_mutex_enter(p->pSrcDb->mutex);
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sqlite3BtreeEnter(p->pSrc);
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if( p->pDestDb ){
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sqlite3_mutex_enter(p->pDestDb->mutex);
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}
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rc = p->rc;
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if( !isFatalError(rc) ){
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Pager * const pSrcPager = sqlite3BtreePager(p->pSrc); /* Source pager */
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Pager * const pDestPager = sqlite3BtreePager(p->pDest); /* Dest pager */
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int ii; /* Iterator variable */
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int nSrcPage = -1; /* Size of source db in pages */
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int bCloseTrans = 0; /* True if src db requires unlocking */
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/* If the source pager is currently in a write-transaction, return
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** SQLITE_BUSY immediately.
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*/
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if( p->pDestDb && p->pSrc->pBt->inTransaction==TRANS_WRITE ){
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rc = SQLITE_BUSY;
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}else{
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rc = SQLITE_OK;
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}
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/* Lock the destination database, if it is not locked already. */
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if( SQLITE_OK==rc && p->bDestLocked==0
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&& SQLITE_OK==(rc = sqlite3BtreeBeginTrans(p->pDest, 2))
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){
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p->bDestLocked = 1;
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sqlite3BtreeGetMeta(p->pDest, BTREE_SCHEMA_VERSION, &p->iDestSchema);
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}
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/* If there is no open read-transaction on the source database, open
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** one now. If a transaction is opened here, then it will be closed
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** before this function exits.
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*/
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if( rc==SQLITE_OK && 0==sqlite3BtreeIsInReadTrans(p->pSrc) ){
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rc = sqlite3BtreeBeginTrans(p->pSrc, 0);
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bCloseTrans = 1;
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}
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/* Do not allow backup if the destination database is in WAL mode
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** and the page sizes are different between source and destination */
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pgszSrc = sqlite3BtreeGetPageSize(p->pSrc);
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pgszDest = sqlite3BtreeGetPageSize(p->pDest);
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destMode = sqlite3PagerGetJournalMode(sqlite3BtreePager(p->pDest));
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if( SQLITE_OK==rc && destMode==PAGER_JOURNALMODE_WAL && pgszSrc!=pgszDest ){
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rc = SQLITE_READONLY;
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}
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/* Now that there is a read-lock on the source database, query the
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** source pager for the number of pages in the database.
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*/
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nSrcPage = (int)sqlite3BtreeLastPage(p->pSrc);
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assert( nSrcPage>=0 );
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for(ii=0; (nPage<0 || ii<nPage) && p->iNext<=(Pgno)nSrcPage && !rc; ii++){
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const Pgno iSrcPg = p->iNext; /* Source page number */
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if( iSrcPg!=PENDING_BYTE_PAGE(p->pSrc->pBt) ){
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DbPage *pSrcPg; /* Source page object */
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rc = sqlite3PagerGet(pSrcPager, iSrcPg, &pSrcPg);
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if( rc==SQLITE_OK ){
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rc = backupOnePage(p, iSrcPg, sqlite3PagerGetData(pSrcPg));
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sqlite3PagerUnref(pSrcPg);
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}
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}
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p->iNext++;
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}
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if( rc==SQLITE_OK ){
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p->nPagecount = nSrcPage;
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p->nRemaining = nSrcPage+1-p->iNext;
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if( p->iNext>(Pgno)nSrcPage ){
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rc = SQLITE_DONE;
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}else if( !p->isAttached ){
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attachBackupObject(p);
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}
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}
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/* Update the schema version field in the destination database. This
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** is to make sure that the schema-version really does change in
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** the case where the source and destination databases have the
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** same schema version.
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*/
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if( rc==SQLITE_DONE
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&& (rc = sqlite3BtreeUpdateMeta(p->pDest,1,p->iDestSchema+1))==SQLITE_OK
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){
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int nDestTruncate;
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if( p->pDestDb ){
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sqlite3ResetInternalSchema(p->pDestDb, 0);
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}
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/* Set nDestTruncate to the final number of pages in the destination
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** database. The complication here is that the destination page
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** size may be different to the source page size.
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**
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** If the source page size is smaller than the destination page size,
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** round up. In this case the call to sqlite3OsTruncate() below will
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** fix the size of the file. However it is important to call
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** sqlite3PagerTruncateImage() here so that any pages in the
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** destination file that lie beyond the nDestTruncate page mark are
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** journalled by PagerCommitPhaseOne() before they are destroyed
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** by the file truncation.
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*/
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assert( pgszSrc==sqlite3BtreeGetPageSize(p->pSrc) );
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assert( pgszDest==sqlite3BtreeGetPageSize(p->pDest) );
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if( pgszSrc<pgszDest ){
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int ratio = pgszDest/pgszSrc;
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nDestTruncate = (nSrcPage+ratio-1)/ratio;
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if( nDestTruncate==(int)PENDING_BYTE_PAGE(p->pDest->pBt) ){
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nDestTruncate--;
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}
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}else{
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nDestTruncate = nSrcPage * (pgszSrc/pgszDest);
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}
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sqlite3PagerTruncateImage(pDestPager, nDestTruncate);
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if( pgszSrc<pgszDest ){
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/* If the source page-size is smaller than the destination page-size,
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** two extra things may need to happen:
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**
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** * The destination may need to be truncated, and
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**
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** * Data stored on the pages immediately following the
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** pending-byte page in the source database may need to be
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** copied into the destination database.
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*/
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const i64 iSize = (i64)pgszSrc * (i64)nSrcPage;
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sqlite3_file * const pFile = sqlite3PagerFile(pDestPager);
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i64 iOff;
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i64 iEnd;
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assert( pFile );
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assert( (i64)nDestTruncate*(i64)pgszDest >= iSize || (
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nDestTruncate==(int)(PENDING_BYTE_PAGE(p->pDest->pBt)-1)
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&& iSize>=PENDING_BYTE && iSize<=PENDING_BYTE+pgszDest
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));
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/* This call ensures that all data required to recreate the original
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** database has been stored in the journal for pDestPager and the
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** journal synced to disk. So at this point we may safely modify
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** the database file in any way, knowing that if a power failure
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** occurs, the original database will be reconstructed from the
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** journal file. */
|
|
rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 1);
|
|
|
|
/* Write the extra pages and truncate the database file as required. */
|
|
iEnd = MIN(PENDING_BYTE + pgszDest, iSize);
|
|
for(
|
|
iOff=PENDING_BYTE+pgszSrc;
|
|
rc==SQLITE_OK && iOff<iEnd;
|
|
iOff+=pgszSrc
|
|
){
|
|
PgHdr *pSrcPg = 0;
|
|
const Pgno iSrcPg = (Pgno)((iOff/pgszSrc)+1);
|
|
rc = sqlite3PagerGet(pSrcPager, iSrcPg, &pSrcPg);
|
|
if( rc==SQLITE_OK ){
|
|
u8 *zData = sqlite3PagerGetData(pSrcPg);
|
|
rc = sqlite3OsWrite(pFile, zData, pgszSrc, iOff);
|
|
}
|
|
sqlite3PagerUnref(pSrcPg);
|
|
}
|
|
if( rc==SQLITE_OK ){
|
|
rc = backupTruncateFile(pFile, iSize);
|
|
}
|
|
|
|
/* Sync the database file to disk. */
|
|
if( rc==SQLITE_OK ){
|
|
rc = sqlite3PagerSync(pDestPager);
|
|
}
|
|
}else{
|
|
rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 0);
|
|
}
|
|
|
|
/* Finish committing the transaction to the destination database. */
|
|
if( SQLITE_OK==rc
|
|
&& SQLITE_OK==(rc = sqlite3BtreeCommitPhaseTwo(p->pDest))
|
|
){
|
|
rc = SQLITE_DONE;
|
|
}
|
|
}
|
|
|
|
/* If bCloseTrans is true, then this function opened a read transaction
|
|
** on the source database. Close the read transaction here. There is
|
|
** no need to check the return values of the btree methods here, as
|
|
** "committing" a read-only transaction cannot fail.
|
|
*/
|
|
if( bCloseTrans ){
|
|
TESTONLY( int rc2 );
|
|
TESTONLY( rc2 = ) sqlite3BtreeCommitPhaseOne(p->pSrc, 0);
|
|
TESTONLY( rc2 |= ) sqlite3BtreeCommitPhaseTwo(p->pSrc);
|
|
assert( rc2==SQLITE_OK );
|
|
}
|
|
|
|
if( rc==SQLITE_IOERR_NOMEM ){
|
|
rc = SQLITE_NOMEM;
|
|
}
|
|
p->rc = rc;
|
|
}
|
|
if( p->pDestDb ){
|
|
sqlite3_mutex_leave(p->pDestDb->mutex);
|
|
}
|
|
sqlite3BtreeLeave(p->pSrc);
|
|
sqlite3_mutex_leave(p->pSrcDb->mutex);
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Release all resources associated with an sqlite3_backup* handle.
|
|
*/
|
|
int sqlite3_backup_finish(sqlite3_backup *p){
|
|
sqlite3_backup **pp; /* Ptr to head of pagers backup list */
|
|
sqlite3_mutex *mutex; /* Mutex to protect source database */
|
|
int rc; /* Value to return */
|
|
|
|
/* Enter the mutexes */
|
|
if( p==0 ) return SQLITE_OK;
|
|
sqlite3_mutex_enter(p->pSrcDb->mutex);
|
|
sqlite3BtreeEnter(p->pSrc);
|
|
mutex = p->pSrcDb->mutex;
|
|
if( p->pDestDb ){
|
|
sqlite3_mutex_enter(p->pDestDb->mutex);
|
|
}
|
|
|
|
/* Detach this backup from the source pager. */
|
|
if( p->pDestDb ){
|
|
p->pSrc->nBackup--;
|
|
}
|
|
if( p->isAttached ){
|
|
pp = sqlite3PagerBackupPtr(sqlite3BtreePager(p->pSrc));
|
|
while( *pp!=p ){
|
|
pp = &(*pp)->pNext;
|
|
}
|
|
*pp = p->pNext;
|
|
}
|
|
|
|
/* If a transaction is still open on the Btree, roll it back. */
|
|
sqlite3BtreeRollback(p->pDest);
|
|
|
|
/* Set the error code of the destination database handle. */
|
|
rc = (p->rc==SQLITE_DONE) ? SQLITE_OK : p->rc;
|
|
sqlite3Error(p->pDestDb, rc, 0);
|
|
|
|
/* Exit the mutexes and free the backup context structure. */
|
|
if( p->pDestDb ){
|
|
sqlite3_mutex_leave(p->pDestDb->mutex);
|
|
}
|
|
sqlite3BtreeLeave(p->pSrc);
|
|
if( p->pDestDb ){
|
|
/* 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(). */
|
|
sqlite3_free(p);
|
|
}
|
|
sqlite3_mutex_leave(mutex);
|
|
return rc;
|
|
}
|
|
|
|
/*
|
|
** Return the number of pages still to be backed up as of the most recent
|
|
** call to sqlite3_backup_step().
|
|
*/
|
|
int sqlite3_backup_remaining(sqlite3_backup *p){
|
|
return p->nRemaining;
|
|
}
|
|
|
|
/*
|
|
** Return the total number of pages in the source database as of the most
|
|
** recent call to sqlite3_backup_step().
|
|
*/
|
|
int sqlite3_backup_pagecount(sqlite3_backup *p){
|
|
return p->nPagecount;
|
|
}
|
|
|
|
/*
|
|
** This function is called after the contents of page iPage of the
|
|
** source database have been modified. If page iPage has already been
|
|
** copied into the destination database, then the data written to the
|
|
** destination is now invalidated. The destination copy of iPage needs
|
|
** to be updated with the new data before the backup operation is
|
|
** complete.
|
|
**
|
|
** It is assumed that the mutex associated with the BtShared object
|
|
** corresponding to the source database is held when this function is
|
|
** called.
|
|
*/
|
|
void sqlite3BackupUpdate(sqlite3_backup *pBackup, Pgno iPage, const u8 *aData){
|
|
sqlite3_backup *p; /* Iterator variable */
|
|
for(p=pBackup; p; p=p->pNext){
|
|
assert( sqlite3_mutex_held(p->pSrc->pBt->mutex) );
|
|
if( !isFatalError(p->rc) && iPage<p->iNext ){
|
|
/* The backup process p has already copied page iPage. But now it
|
|
** has been modified by a transaction on the source pager. Copy
|
|
** the new data into the backup.
|
|
*/
|
|
int rc = backupOnePage(p, iPage, aData);
|
|
assert( rc!=SQLITE_BUSY && rc!=SQLITE_LOCKED );
|
|
if( rc!=SQLITE_OK ){
|
|
p->rc = rc;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
** Restart the backup process. This is called when the pager layer
|
|
** detects that the database has been modified by an external database
|
|
** connection. In this case there is no way of knowing which of the
|
|
** pages that have been copied into the destination database are still
|
|
** valid and which are not, so the entire process needs to be restarted.
|
|
**
|
|
** It is assumed that the mutex associated with the BtShared object
|
|
** corresponding to the source database is held when this function is
|
|
** called.
|
|
*/
|
|
void sqlite3BackupRestart(sqlite3_backup *pBackup){
|
|
sqlite3_backup *p; /* Iterator variable */
|
|
for(p=pBackup; p; p=p->pNext){
|
|
assert( sqlite3_mutex_held(p->pSrc->pBt->mutex) );
|
|
p->iNext = 1;
|
|
}
|
|
}
|
|
|
|
#ifndef SQLITE_OMIT_VACUUM
|
|
/*
|
|
** Copy the complete content of pBtFrom into pBtTo. A transaction
|
|
** must be active for both files.
|
|
**
|
|
** The size of file pTo may be reduced by this operation. If anything
|
|
** goes wrong, the transaction on pTo is rolled back. If successful, the
|
|
** transaction is committed before returning.
|
|
*/
|
|
int sqlite3BtreeCopyFile(Btree *pTo, Btree *pFrom){
|
|
int rc;
|
|
sqlite3_backup b;
|
|
sqlite3BtreeEnter(pTo);
|
|
sqlite3BtreeEnter(pFrom);
|
|
|
|
/* Set up an sqlite3_backup object. sqlite3_backup.pDestDb must be set
|
|
** to 0. This is used by the implementations of sqlite3_backup_step()
|
|
** and sqlite3_backup_finish() to detect that they are being called
|
|
** from this function, not directly by the user.
|
|
*/
|
|
memset(&b, 0, sizeof(b));
|
|
b.pSrcDb = pFrom->db;
|
|
b.pSrc = pFrom;
|
|
b.pDest = pTo;
|
|
b.iNext = 1;
|
|
|
|
/* 0x7FFFFFFF is the hard limit for the number of pages in a database
|
|
** file. By passing this as the number of pages to copy to
|
|
** sqlite3_backup_step(), we can guarantee that the copy finishes
|
|
** within a single call (unless an error occurs). The assert() statement
|
|
** checks this assumption - (p->rc) should be set to either SQLITE_DONE
|
|
** or an error code.
|
|
*/
|
|
sqlite3_backup_step(&b, 0x7FFFFFFF);
|
|
assert( b.rc!=SQLITE_OK );
|
|
rc = sqlite3_backup_finish(&b);
|
|
if( rc==SQLITE_OK ){
|
|
pTo->pBt->pageSizeFixed = 0;
|
|
}
|
|
|
|
sqlite3BtreeLeave(pFrom);
|
|
sqlite3BtreeLeave(pTo);
|
|
return rc;
|
|
}
|
|
#endif /* SQLITE_OMIT_VACUUM */
|