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Changes to src/wal.c.

   447    447     Wal *pWal,                      /* The write-ahead log */
   448    448     u32 *piPage,                    /* OUT: Database page number for frame */
   449    449     u32 *pnTruncate,                /* OUT: New db size (or 0 if not commit) */
   450    450     u8 *aData,                      /* Pointer to page data (for checksum) */
   451    451     u8 *aFrame                      /* Frame data */
   452    452   ){
   453    453     int nativeCksum;                /* True for native byte-order checksums */
          454  +  u32 pgno;                       /* Page number of the frame */
   454    455     u32 aCksum[2];
   455    456     assert( WAL_FRAME_HDRSIZE==24 );
   456    457   
   457    458     /* A frame is only valid if the salt values in the frame-header
   458    459     ** match the salt values in the wal-header. 
   459    460     */
   460    461     if( memcmp(&pWal->hdr.aSalt, &aFrame[8], 8)!=0 ){
   461    462       return 0;
   462    463     }
          464  +
          465  +  /* A frame is only valid if the page number is creater than zero.
          466  +  */
          467  +  pgno = sqlite3Get4byte(&aFrame[0]);
          468  +  if( pgno==0 ){
          469  +    return 0;
          470  +  }
   463    471   
   464    472     /* A frame is only valid if a checksum of the first 16 bytes
   465    473     ** of the frame-header, and the frame-data matches
   466    474     ** the checksum in the last 8 bytes of the frame-header.
   467    475     */
   468    476     nativeCksum = (pWal->hdr.bigEndCksum==SQLITE_BIGENDIAN);
   469    477     walChecksumBytes(nativeCksum, aFrame, 16, 0, aCksum);
................................................................................
   474    482       /* Checksum failed. */
   475    483       return 0;
   476    484     }
   477    485   
   478    486     /* If we reach this point, the frame is valid.  Return the page number
   479    487     ** and the new database size.
   480    488     */
   481         -  *piPage = sqlite3Get4byte(&aFrame[0]);
          489  +  *piPage = pgno;
   482    490     *pnTruncate = sqlite3Get4byte(&aFrame[4]);
   483    491     return 1;
   484    492   }
   485    493   
   486    494   /*
   487    495   ** Define the parameters of the hash tables in the wal-index file. There
   488    496   ** is a hash-table following every HASHTABLE_NPAGE page numbers in the