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Overview
Comment:Avoid passing strings with a single nul-terminator (two are required) to the VFS xOpen() method from within the code that checks to see if a master-journal file may be safely deleted.
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SHA1:2544f233f1041a42bbdbb5413d2bc92b2a2e0397
User & Date: dan 2012-01-10 17:28:10
References
2012-01-10
23:18
Only require double-zero terminators on database filenames, not any every files supplied to the xOpen method. This backs out [2544f233f1]. Also refactor the fillInUnixFile() routine in os_unix.c to reduce the number of parameters. check-in: cb774b26 user: drh tags: trunk
Context
2012-01-10
17:59
Refactor sqlite3OsFileControlNoFail() into sqlite3FileControlHint(). check-in: 722735a4 user: drh tags: trunk
17:28
Avoid passing strings with a single nul-terminator (two are required) to the VFS xOpen() method from within the code that checks to see if a master-journal file may be safely deleted. check-in: 2544f233 user: dan tags: trunk
16:56
Add function sqlite3OsFileControlNoFail(), which is the same as sqlite3OsFileControl() except that it does not simulate OOM errors. This saves adding calls to the BenignMalloc() functions around each of the invocations of sqliteOsFileControl() that ignore the return code. check-in: af59b182 user: dan tags: trunk
Changes
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Changes to src/pager.c.

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  ** sqlite3_malloc() and pointed to by zMasterJournal.   Also obtain
  ** sufficient space (in zMasterPtr) to hold the names of master
  ** journal files extracted from regular rollback-journals.
  */
  rc = sqlite3OsFileSize(pMaster, &nMasterJournal);
  if( rc!=SQLITE_OK ) goto delmaster_out;
  nMasterPtr = pVfs->mxPathname+1;
  zMasterJournal = sqlite3Malloc((int)nMasterJournal + nMasterPtr + 1);
  if( !zMasterJournal ){
    rc = SQLITE_NOMEM;
    goto delmaster_out;
  }
  zMasterPtr = &zMasterJournal[nMasterJournal+1];
  rc = sqlite3OsRead(pMaster, zMasterJournal, (int)nMasterJournal, 0);
  if( rc!=SQLITE_OK ) goto delmaster_out;





  zMasterJournal[nMasterJournal] = 0;


  zJournal = zMasterJournal;
  while( (zJournal-zMasterJournal)<nMasterJournal ){

    int exists;













    rc = sqlite3OsAccess(pVfs, zJournal, SQLITE_ACCESS_EXISTS, &exists);
    if( rc!=SQLITE_OK ){
      goto delmaster_out;
    }
    if( exists ){
      /* One of the journals pointed to by the master journal exists.
      ** Open it and check if it points at the master journal. If
      ** so, return without deleting the master journal file.
      */
      int c;
      int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MAIN_JOURNAL);
      rc = sqlite3OsOpen(pVfs, zJournal, pJournal, flags, 0);
      if( rc!=SQLITE_OK ){
        goto delmaster_out;
      }

      rc = readMasterJournal(pJournal, zMasterPtr, nMasterPtr);
      sqlite3OsClose(pJournal);
      if( rc!=SQLITE_OK ){
        goto delmaster_out;
      }

      c = zMasterPtr[0]!=0 && strcmp(zMasterPtr, zMaster)==0;
      if( c ){
        /* We have a match. Do not delete the master journal file. */
        goto delmaster_out;
      }
    }
    zJournal += (sqlite3Strlen30(zJournal)+1);

  }
 
  sqlite3OsClose(pMaster);
  rc = sqlite3OsDelete(pVfs, zMaster, 0);

delmaster_out:
  sqlite3_free(zMasterJournal);







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  ** sqlite3_malloc() and pointed to by zMasterJournal.   Also obtain
  ** sufficient space (in zMasterPtr) to hold the names of master
  ** journal files extracted from regular rollback-journals.
  */
  rc = sqlite3OsFileSize(pMaster, &nMasterJournal);
  if( rc!=SQLITE_OK ) goto delmaster_out;
  nMasterPtr = pVfs->mxPathname+1;
  zMasterJournal = sqlite3Malloc((int)nMasterJournal + nMasterPtr + 2);
  if( !zMasterJournal ){
    rc = SQLITE_NOMEM;
    goto delmaster_out;
  }
  zMasterPtr = &zMasterJournal[nMasterJournal+2];
  rc = sqlite3OsRead(pMaster, zMasterJournal, (int)nMasterJournal, 0);
  if( rc!=SQLITE_OK ) goto delmaster_out;

  /* Ensure that even if the contents of the master journal file are corrupt,
  ** they are terminated by a pair of 0x00 bytes. This prevents buffer 
  ** overreads in any calls made to sqlite3_uri_xxx() via sqlite3OsOpen()
  ** below.  */
  zMasterJournal[nMasterJournal] = 0;
  zMasterJournal[nMasterJournal+1] = 0;

  zJournal = zMasterJournal;
  while( (zJournal-zMasterJournal)<nMasterJournal ){
    char c;
    int exists;
    int nJournal = sqlite3Strlen30(zJournal);

    /* The sqlite3OsAccess() and sqlite3OsOpen() functions require argument
    ** strings that may be passed to the sqlite3_uri_xxx() API functions.
    ** In this case that means strings terminated by a pair of 0x00 bytes.
    ** But the master-journal file contains strings terminated by a single
    ** 0x00 only. So temporarily replace the first byte of the following
    ** string with a second 0x00. The original value is restored before the
    ** next iteration of this loop.  */
    assert( &zJournal[nJournal+1] < zMasterPtr );
    c = zJournal[nJournal+1];
    zJournal[nJournal+1] = '\0';

    rc = sqlite3OsAccess(pVfs, zJournal, SQLITE_ACCESS_EXISTS, &exists);
    if( rc!=SQLITE_OK ){
      goto delmaster_out;
    }
    if( exists ){
      /* One of the journals pointed to by the master journal exists.
      ** Open it and check if it points at the master journal. If
      ** so, return without deleting the master journal file.
      */

      int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MAIN_JOURNAL);
      rc = sqlite3OsOpen(pVfs, zJournal, pJournal, flags, 0);
      if( rc!=SQLITE_OK ){
        goto delmaster_out;
      }

      rc = readMasterJournal(pJournal, zMasterPtr, nMasterPtr);
      sqlite3OsClose(pJournal);
      if( rc!=SQLITE_OK ){
        goto delmaster_out;
      }

      if( zMasterPtr[0]!=0 && strcmp(zMasterPtr, zMaster)==0 ){

        /* We have a match. Do not delete the master journal file. */
        goto delmaster_out;
      }
    }
    zJournal += nJournal+1;
    zJournal[0] = c;
  }
 
  sqlite3OsClose(pMaster);
  rc = sqlite3OsDelete(pVfs, zMaster, 0);

delmaster_out:
  sqlite3_free(zMasterJournal);