/ Check-in [70f20425]
Login

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:If xAccess() fails while attempting to detect a hot-journal file, do not assume that the error was an out-of-memory condition. (CVS 5515)
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 70f20425e8197bce74b412f65050d954acb5bde4
User & Date: danielk1977 2008-08-01 10:50:23
Context
2008-08-01
14:33
Applied patch to fix failure with build on gcc-powerpc (provide sqlite3Hwtime). Ticket #3256. (CVS 5516) check-in: c9ecd88e user: shane tags: trunk
10:50
If xAccess() fails while attempting to detect a hot-journal file, do not assume that the error was an out-of-memory condition. (CVS 5515) check-in: 70f20425 user: danielk1977 tags: trunk
2008-07-31
17:35
Define _GNU_SOURCE only if it is not already defined. Ticket #3263. (CVS 5514) check-in: bc5abd31 user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/pager.c.

14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
....
3140
3141
3142
3143
3144
3145
3146
3147
3148

3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163

3164

3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
....
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463

3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482

3483
3484
3485
3486
3487
3488
3489
....
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.467 2008/07/22 05:18:01 shane Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include <assert.h>
#include <string.h>

/*
................................................................................
** journal file that has been deleted, and hence not be hot.  Or
** the header of the journal might be zeroed out.  This routine
** does not discover these cases of a non-hot journal - if the
** journal file exists and is not empty this routine assumes it
** is hot.  The pager_playback() routine will discover that the
** journal file is not really hot and will no-op.
*/
static int hasHotJournal(Pager *pPager){
  sqlite3_vfs *pVfs = pPager->pVfs;

  int res = 0;
  if( pPager->useJournal && pPager->fd->pMethods ){
    int rc;
    int exists;
    int locked;

    rc = sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &exists);
    if( rc==SQLITE_OK && exists ){
      rc = sqlite3OsCheckReservedLock(pPager->fd, &locked);
    }

    if( rc==SQLITE_OK && exists && !locked ){
      int nPage;
      rc = sqlite3PagerPagecount(pPager, &nPage);
      if( rc==SQLITE_OK && nPage==0 ){

        sqlite3OsDelete(pVfs, pPager->zJournal, 0);

        exists = 0;
      }
    }

    res = (rc!=SQLITE_OK ? -1 : (exists && !locked));
  }

  return res;
}

/*
** Try to find a page in the cache that can be recycled. 
**
** This routine may return SQLITE_IOERR, SQLITE_FULL or SQLITE_OK. It 
** does not set the pPager->errCode variable.
................................................................................
**
** Immediately after obtaining the shared lock (if required), this function
** checks for a hot-journal file. If one is found, an emergency rollback
** is performed immediately.
*/
static int pagerSharedLock(Pager *pPager){
  int rc = SQLITE_OK;
  int isHot = 0;

  /* If this database is opened for exclusive access, has no outstanding 
  ** page references and is in an error-state, now is the chance to clear
  ** the error. Discard the contents of the pager-cache and treat any
  ** open journal file as a hot-journal.
  */
  if( !MEMDB && pPager->exclusiveMode && pPager->nRef==0 && pPager->errCode ){
    if( pPager->journalOpen ){
      isHot = 1;
    }
    pPager->errCode = SQLITE_OK;
    pager_reset(pPager);
  }

  /* If the pager is still in an error state, do not proceed. The error 
  ** state will be cleared at some point in the future when all page 
  ** references are dropped and the cache can be discarded.
  */
  if( pPager->errCode && pPager->errCode!=SQLITE_FULL ){
    return pPager->errCode;
  }

  if( pPager->state==PAGER_UNLOCK || isHot ){
    sqlite3_vfs *pVfs = pPager->pVfs;
    if( !MEMDB ){

      assert( pPager->nRef==0 );
      if( !pPager->noReadlock ){
        rc = pager_wait_on_lock(pPager, SHARED_LOCK);
        if( rc!=SQLITE_OK ){
          assert( pPager->state==PAGER_UNLOCK );
          return pager_error(pPager, rc);
        }
        assert( pPager->state>=SHARED_LOCK );
      }
  
      /* If a journal file exists, and there is no RESERVED lock on the
      ** database file, then it either needs to be played back or deleted.
      */
      rc = hasHotJournal(pPager);
      if( rc<0 ){
        rc = SQLITE_IOERR_NOMEM;
        goto failed;
      }
      if( rc==1 || isHot ){

        /* Get an EXCLUSIVE lock on the database file. At this point it is
        ** important that a RESERVED lock is not obtained on the way to the
        ** EXCLUSIVE lock. If it were, another process might open the
        ** database file, detect the RESERVED lock, and conclude that the
        ** database is safe to read while this process is still rolling it 
        ** back.
        ** 
................................................................................
 
        /* Open the journal for read/write access. This is because in 
        ** exclusive-access mode the file descriptor will be kept open and
        ** possibly used for a transaction later on. On some systems, the
        ** OsTruncate() call used in exclusive-access mode also requires
        ** a read/write file handle.
        */
        if( !isHot && pPager->journalOpen==0 ){
          int res;
          rc = sqlite3OsAccess(pVfs,pPager->zJournal,SQLITE_ACCESS_EXISTS,&res);
          if( rc==SQLITE_OK ){
            if( res ){
              int fout = 0;
              int f = SQLITE_OPEN_READWRITE|SQLITE_OPEN_MAIN_JOURNAL;
              assert( !pPager->tempFile );







|







 







|

>
|

<











|
>
|
>
|
|
|
|
<


|







 







|








|













|


>













|
|
|
|
|
|
>







 







|







14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
....
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151

3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170

3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
....
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
....
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.468 2008/08/01 10:50:23 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include <assert.h>
#include <string.h>

/*
................................................................................
** journal file that has been deleted, and hence not be hot.  Or
** the header of the journal might be zeroed out.  This routine
** does not discover these cases of a non-hot journal - if the
** journal file exists and is not empty this routine assumes it
** is hot.  The pager_playback() routine will discover that the
** journal file is not really hot and will no-op.
*/
static int hasHotJournal(Pager *pPager, int *pExists){
  sqlite3_vfs *pVfs = pPager->pVfs;
  int rc = SQLITE_OK;
  *pExists = 0;
  if( pPager->useJournal && pPager->fd->pMethods ){

    int exists;
    int locked;

    rc = sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &exists);
    if( rc==SQLITE_OK && exists ){
      rc = sqlite3OsCheckReservedLock(pPager->fd, &locked);
    }

    if( rc==SQLITE_OK && exists && !locked ){
      int nPage;
      rc = sqlite3PagerPagecount(pPager, &nPage);
      if( rc==SQLITE_OK ){
        if( nPage==0 ){
          sqlite3OsDelete(pVfs, pPager->zJournal, 0);
        }else{
          *pExists = 1;
        }
      }
    }

  }

  return rc;
}

/*
** Try to find a page in the cache that can be recycled. 
**
** This routine may return SQLITE_IOERR, SQLITE_FULL or SQLITE_OK. It 
** does not set the pPager->errCode variable.
................................................................................
**
** Immediately after obtaining the shared lock (if required), this function
** checks for a hot-journal file. If one is found, an emergency rollback
** is performed immediately.
*/
static int pagerSharedLock(Pager *pPager){
  int rc = SQLITE_OK;
  int isErrorReset = 0;

  /* If this database is opened for exclusive access, has no outstanding 
  ** page references and is in an error-state, now is the chance to clear
  ** the error. Discard the contents of the pager-cache and treat any
  ** open journal file as a hot-journal.
  */
  if( !MEMDB && pPager->exclusiveMode && pPager->nRef==0 && pPager->errCode ){
    if( pPager->journalOpen ){
      isErrorReset = 1;
    }
    pPager->errCode = SQLITE_OK;
    pager_reset(pPager);
  }

  /* If the pager is still in an error state, do not proceed. The error 
  ** state will be cleared at some point in the future when all page 
  ** references are dropped and the cache can be discarded.
  */
  if( pPager->errCode && pPager->errCode!=SQLITE_FULL ){
    return pPager->errCode;
  }

  if( pPager->state==PAGER_UNLOCK || isErrorReset ){
    sqlite3_vfs *pVfs = pPager->pVfs;
    if( !MEMDB ){
      int isHotJournal;
      assert( pPager->nRef==0 );
      if( !pPager->noReadlock ){
        rc = pager_wait_on_lock(pPager, SHARED_LOCK);
        if( rc!=SQLITE_OK ){
          assert( pPager->state==PAGER_UNLOCK );
          return pager_error(pPager, rc);
        }
        assert( pPager->state>=SHARED_LOCK );
      }
  
      /* If a journal file exists, and there is no RESERVED lock on the
      ** database file, then it either needs to be played back or deleted.
      */
      if( !isErrorReset ){
        rc = hasHotJournal(pPager, &isHotJournal);
        if( rc!=SQLITE_OK ){
          goto failed;
        }
      }
      if( isErrorReset || isHotJournal ){
        /* Get an EXCLUSIVE lock on the database file. At this point it is
        ** important that a RESERVED lock is not obtained on the way to the
        ** EXCLUSIVE lock. If it were, another process might open the
        ** database file, detect the RESERVED lock, and conclude that the
        ** database is safe to read while this process is still rolling it 
        ** back.
        ** 
................................................................................
 
        /* Open the journal for read/write access. This is because in 
        ** exclusive-access mode the file descriptor will be kept open and
        ** possibly used for a transaction later on. On some systems, the
        ** OsTruncate() call used in exclusive-access mode also requires
        ** a read/write file handle.
        */
        if( !isErrorReset && pPager->journalOpen==0 ){
          int res;
          rc = sqlite3OsAccess(pVfs,pPager->zJournal,SQLITE_ACCESS_EXISTS,&res);
          if( rc==SQLITE_OK ){
            if( res ){
              int fout = 0;
              int f = SQLITE_OPEN_READWRITE|SQLITE_OPEN_MAIN_JOURNAL;
              assert( !pPager->tempFile );