SQLite

Check-in [9580ecb7e3]
Login

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

Overview
Comment:Make use of the extra information in the WAL header and frame header to enhance robustness.
Downloads: Tarball | ZIP archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 9580ecb7e3beb1949a71784a3dcd1823a88e4a9d
User & Date: drh 2010-05-20 21:21:10.000
Context
2010-05-20
23:51
Add a new xShmBarrier method to the VFS - a shared-memory fence operation. Implement the same in both unix and win32. Use it to make the WAL subsystem more robust. (check-in: 1bd011c9fe user: drh tags: trunk)
21:21
Make use of the extra information in the WAL header and frame header to enhance robustness. (check-in: 9580ecb7e3 user: drh tags: trunk)
16:45
Convert the wal-header and frame-header to 24 bytes. Extra information in both headers is designed to enhance robustness after crashes, though the extra information is currently unused. This is a snapshot of a work in progress. (check-in: 669706431f user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/wal.c.
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
*************************************************************************
**
** This file contains the implementation of a write-ahead log (WAL) used in 
** "journal_mode=WAL" mode.
**
** WRITE-AHEAD LOG (WAL) FILE FORMAT
**
** A wal file consists of a header followed by zero or more "frames".
** Each frame records the revised content of a single page from the
** database file.  All changes to the database are recorded by writing
** frames into the WAL.  Transactions commit when a frame is written that
** contains a commit marker.  A single WAL can and usually does record 
** multiple transactions.  Periodically, the content of the WAL is
** transferred back into the database file in an operation called a
** "checkpoint".







|







11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
*************************************************************************
**
** This file contains the implementation of a write-ahead log (WAL) used in 
** "journal_mode=WAL" mode.
**
** WRITE-AHEAD LOG (WAL) FILE FORMAT
**
** A WAL file consists of a header followed by zero or more "frames".
** Each frame records the revised content of a single page from the
** database file.  All changes to the database are recorded by writing
** frames into the WAL.  Transactions commit when a frame is written that
** contains a commit marker.  A single WAL can and usually does record 
** multiple transactions.  Periodically, the content of the WAL is
** transferred back into the database file in an operation called a
** "checkpoint".
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55






















56
57
58
59
60
61
62
** The WAL header is 24 bytes in size and consists of the following six
** big-endian 32-bit unsigned integer values:
**
**     0: Magic number.  0x377f0682 (big endian)
**     4: File format version.  Currently 3007000
**     8: Database page size.  Example: 1024
**    12: Checkpoint sequence number
**    16: Salt-1, random integer that changes with each checkpoint
**    20: Salt-2, a different random integer changing with salt-1
**
** Immediately following the wal-header are zero or more frames. Each
** frame consists of a 24-byte frame-header followed by a <page-size> bytes
** of page data. The frame-header is broken into 6 big-endian 32-bit unsigned 
** integer values, as follows:
**
**     0: Page number.
**     4: For commit records, the size of the database image in pages 
**        after the commit. For all other records, zero.
**     8: Checkpoint sequence number (copied from the header)
**    12: Salt-1 (copied from the header)
**    16: Checksum-1.
**    20: Checksum-2.






















**
** READER ALGORITHM
**
** To read a page from the database (call it page number P), a reader
** first checks the WAL to see if it contains page P.  If so, then the
** last valid instance of page P that is or is followed by a commit frame
** become the value read.  If the WAL contains no copies of page P that







|
|









|
|


>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>







34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
** The WAL header is 24 bytes in size and consists of the following six
** big-endian 32-bit unsigned integer values:
**
**     0: Magic number.  0x377f0682 (big endian)
**     4: File format version.  Currently 3007000
**     8: Database page size.  Example: 1024
**    12: Checkpoint sequence number
**    16: Salt-1, random integer incremented with each checkpoint
**    20: Salt-2, a different random integer changing with each ckpt
**
** Immediately following the wal-header are zero or more frames. Each
** frame consists of a 24-byte frame-header followed by a <page-size> bytes
** of page data. The frame-header is broken into 6 big-endian 32-bit unsigned 
** integer values, as follows:
**
**     0: Page number.
**     4: For commit records, the size of the database image in pages 
**        after the commit. For all other records, zero.
**     8: Salt-1 (copied from the header)
**    12: Salt-2 (copied from the header)
**    16: Checksum-1.
**    20: Checksum-2.
**
** A frame is considered valid if and only if the following conditions are
** true:
**
**    (1) The salt-1 and salt-2 values in the frame-header match
**        salt values in the wal-header
**
**    (2) The checksum values in the final 8 bytes of the frame-header
**        exactly match the checksum computed consecutively on
**        (a) the first 16 bytes of the frame-header, and
**        (b) the frame data.
**
** On a checkpoint, the WAL is first VFS.xSync-ed, then valid content of the
** WAL is transferred into the database, then the database is VFS.xSync-ed.
** The VFS.xSync operations server as write barriers - all writes launched
** before the xSync must complete before any write that launches after the
** xSync begins.
**
** After each checkpoint, the salt-1 value is incremented and the salt-2
** value is randomized.  This prevents old and new frames in the WAL from
** being considered valid at the same time and being checkpointing together
** following a crash.
**
** READER ALGORITHM
**
** To read a page from the database (call it page number P), a reader
** first checks the WAL to see if it contains page P.  If so, then the
** last valid instance of page P that is or is followed by a commit frame
** become the value read.  If the WAL contains no copies of page P that
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220

/* Object declarations */
typedef struct WalIndexHdr WalIndexHdr;
typedef struct WalIterator WalIterator;


/*
** The following object stores information from the wal-index header.
**
** This object is *not* a copy of the wal-index header.
**
** Member variables iCheck1 and iCheck2 contain the checksum for the
** last frame written to the wal, or 2 and 3 respectively if the log 
** is currently empty.
*/
struct WalIndexHdr {
  u32 iChange;          /* Counter incremented each transaction */
  u32 szPage;           /* Database page size in bytes */
  u32 mxFrame;          /* Index of last valid frame in the WAL */
  u32 nPage;            /* Size of database in pages */
  u32 iCheck1;          /* Checksum value 1 */
  u32 iCheck2;          /* Checksum value 2 */
};

/* Size of serialized WalIndexHdr object. */
#define WALINDEX_HDR_NFIELD (sizeof(WalIndexHdr) / sizeof(u32))

/* A block of 16 bytes beginning at WALINDEX_LOCK_OFFSET is reserved
** for locks. Since some systems only feature mandatory file-locks, we
** do not read or write data from the region of the file on which locks
** are applied.
*/
#define WALINDEX_LOCK_OFFSET   ((sizeof(WalIndexHdr))+2*sizeof(u32))
#define WALINDEX_LOCK_RESERVED 8

/* Size of header before each frame in wal */
#define WAL_FRAME_HDRSIZE 24

/* Size of write ahead log header */
#define WAL_HDRSIZE 24







<
<
|
<
<
<
<


|
|
|
|
|
|


<
<
|
|
|
|
<

|







203
204
205
206
207
208
209


210




211
212
213
214
215
216
217
218
219
220


221
222
223
224

225
226
227
228
229
230
231
232
233

/* Object declarations */
typedef struct WalIndexHdr WalIndexHdr;
typedef struct WalIterator WalIterator;


/*


** The following object holds an exact copy of the wal-index header.




*/
struct WalIndexHdr {
  u32 iChange;      /* Counter incremented each transaction */
  u32 szPage;       /* Database page size in bytes */
  u32 mxFrame;      /* Index of last valid frame in the WAL */
  u32 nPage;        /* Size of database in pages */
  u32 aSalt[2];     /* Salt-1 and salt-2 values copied from WAL header */
  u32 aCksum[2];    /* Checksum over all prior fields */
};



/* A block of WALINDEX_LOCK_RESERVED bytes beginning at
** WALINDEX_LOCK_OFFSET is reserved for locks. Since some systems
** only support mandatory file-locks, we do not read or write data
** from the region of the file on which locks are applied.

*/
#define WALINDEX_LOCK_OFFSET   (sizeof(WalIndexHdr))
#define WALINDEX_LOCK_RESERVED 8

/* Size of header before each frame in wal */
#define WAL_FRAME_HDRSIZE 24

/* Size of write ahead log header */
#define WAL_HDRSIZE 24
241
242
243
244
245
246
247

248
249
250
251
252
253
254
255
256
  volatile u32 *pWiData;     /* Pointer to wal-index content in memory */
  u8 lockState;              /* SQLITE_SHM_xxxx constant showing lock state */
  u8 readerType;             /* SQLITE_SHM_READ or SQLITE_SHM_READ_FULL */
  u8 exclusiveMode;          /* Non-zero if connection is in exclusive mode */
  u8 isWindexOpen;           /* True if ShmOpen() called on pDbFd */
  WalIndexHdr hdr;           /* Wal-index for current snapshot */
  char *zWalName;            /* Name of WAL file */

  u32 nCkpt;                 /* Checkpoint sequence number */
  u32 iSalt1, iSalt2;        /* Two random salt values */
};


/*
** This structure is used to implement an iterator that loops through
** all frames in the WAL in database page order. Where two or more frames
** correspond to the same database page, the iterator visits only the 







>
|
<







254
255
256
257
258
259
260
261
262

263
264
265
266
267
268
269
  volatile u32 *pWiData;     /* Pointer to wal-index content in memory */
  u8 lockState;              /* SQLITE_SHM_xxxx constant showing lock state */
  u8 readerType;             /* SQLITE_SHM_READ or SQLITE_SHM_READ_FULL */
  u8 exclusiveMode;          /* Non-zero if connection is in exclusive mode */
  u8 isWindexOpen;           /* True if ShmOpen() called on pDbFd */
  WalIndexHdr hdr;           /* Wal-index for current snapshot */
  char *zWalName;            /* Name of WAL file */
  int szPage;                /* Database page size */
  u32 nCkpt;                 /* Checkpoint sequence counter in the wal-header */

};


/*
** This structure is used to implement an iterator that loops through
** all frames in the WAL in database page order. Where two or more frames
** correspond to the same database page, the iterator visits only the 
274
275
276
277
278
279
280
281

282

283


284
285





286


287



288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
    u8 *aIndex;             /* i0, i1, i2... such that aPgno[iN] ascending */
    u32 *aPgno;             /* 256 page numbers.  Pointer to Wal.pWiData */
  } aSegment[1];        /* One for every 256 entries in the WAL */
};


/*
** Generate an 8 byte checksum based on the data in array aByte[] and the

** initial values of aCksum[0] and aCksum[1]. The checksum is written 

** back into aCksum[] before returning.


*/
static void walChecksumBytes(u8 *a, int nByte, u32 *aCksum){





  u32 s1 = aCksum[0];


  u32 s2 = aCksum[1];



  u8 *aEnd = (u8*)&a[nByte];

  assert( nByte>=8 );
  assert( (nByte&0x00000003)==0 );

  do {
    s1 += (a[0]<<24) + (a[1]<<16) + (a[2]<<8) + a[3] + s2;
    s2 += (a[4]<<24) + (a[5]<<16) + (a[6]<<8) + a[7] + s1;
    a += 8;
  }while( a<aEnd );
  aCksum[0] = s1;
  aCksum[1] = s2;
}

/*
** Attempt to change the lock status.
**
** When changing the lock status to SQLITE_SHM_READ, store the
** type of reader lock (either SQLITE_SHM_READ or SQLITE_SHM_READ_FULL)







|
>
|
>
|
>
>

|
>
>
>
>
>
|
>
>
|
>
>
>










|
|







287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
    u8 *aIndex;             /* i0, i1, i2... such that aPgno[iN] ascending */
    u32 *aPgno;             /* 256 page numbers.  Pointer to Wal.pWiData */
  } aSegment[1];        /* One for every 256 entries in the WAL */
};


/*
** Generate or extend an 8 byte checksum based on the data in 
** array aByte[] and the initial values of aIn[0] and aIn[1] (or
** initial values of 0 and 0 if aIn==NULL).
**
** The checksum is written back into aOut[] before returning.
**
** nByte must be a positive multiple of 8.
*/
static void walChecksumBytes(
  u8 *a,           /* Content to be checksummed */
  int nByte,       /* Bytes of content in a[].  Must be a multiple of 8. */
  const u32 *aIn,  /* Initial checksum value input */
  u32 *aOut        /* OUT: Final checksum value output */
){
  u32 s1, s2;
  if( aIn ){
    s1 = aIn[0];
    s2 = aIn[1];
  }else{
    s1 = s2 = 0;
  }
  u8 *aEnd = (u8*)&a[nByte];

  assert( nByte>=8 );
  assert( (nByte&0x00000003)==0 );

  do {
    s1 += (a[0]<<24) + (a[1]<<16) + (a[2]<<8) + a[3] + s2;
    s2 += (a[4]<<24) + (a[5]<<16) + (a[6]<<8) + a[7] + s1;
    a += 8;
  }while( a<aEnd );
  aOut[0] = s1;
  aOut[1] = s2;
}

/*
** Attempt to change the lock status.
**
** When changing the lock status to SQLITE_SHM_READ, store the
** type of reader lock (either SQLITE_SHM_READ or SQLITE_SHM_READ_FULL)
319
320
321
322
323
324
325
326


327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360

361
362
363
364
365
366
367
368
369
370
371
372
373
374
375


376
377
378
379
380
381
382
383
384
385
386
387

388
389
390



391
392
393
394
395
396
397
398



399
400
401
402
403
404
405
406
407



408
409
410
411
412
413
414
      pWal->lockState = SQLITE_SHM_READ;
    }
  }
  return rc;
}

/*
** Update the header of the wal-index file.


*/
static void walIndexWriteHdr(Wal *pWal, WalIndexHdr *pHdr){
  volatile u32 *aHdr = pWal->pWiData;                 /* Write header here */
  volatile u32 *aCksum = &aHdr[WALINDEX_HDR_NFIELD];  /* Write cksum here */

  assert( WALINDEX_HDR_NFIELD==sizeof(WalIndexHdr)/4 );
  assert( aHdr!=0 );
  memcpy((void*)aHdr, pHdr, sizeof(WalIndexHdr));
  aCksum[0] = aCksum[1] = 1;
  walChecksumBytes((u8*)aHdr, sizeof(WalIndexHdr), (u32*)aCksum);
}

/*
** This function encodes a single frame header and writes it to a buffer
** supplied by the caller. A frame-header is made up of a series of 
** 4-byte big-endian integers, as follows:
**
**     0: Page number.
**     4: For commit records, the size of the database image in pages 
**        after the commit. For all other records, zero.
**     8: Checkpoint sequence number (copied from the header)
**    12: Salt-1 (copied from the header)
**    16: Checksum-1.
**    20: Checksum-2.
*/
static void walEncodeFrame(
  Wal *pWal,                      /* The write-ahead log */
  u32 *aCksum,                    /* IN/OUT: Checksum values */
  u32 iPage,                      /* Database page number for frame */
  u32 nTruncate,                  /* New db size (or 0 for non-commit frames) */
  int nData,                      /* Database page size (size of aData[]) */
  u8 *aData,                      /* Pointer to page data (for checksum) */
  u8 *aFrame                      /* OUT: Write encoded frame here */
){

  assert( WAL_FRAME_HDRSIZE==24 );

  sqlite3Put4byte(&aFrame[0], iPage);
  sqlite3Put4byte(&aFrame[4], nTruncate);
  sqlite3Put4byte(&aFrame[8], pWal->nCkpt);
  sqlite3Put4byte(&aFrame[12], pWal->iSalt1);

  walChecksumBytes(aFrame, 8, aCksum);
  walChecksumBytes(aData, nData, aCksum);

  sqlite3Put4byte(&aFrame[16], aCksum[0]);
  sqlite3Put4byte(&aFrame[20], aCksum[1]);
}

/*


** Return 1 and populate *piPage, *pnTruncate and aCksum if the 
** frame checksum looks Ok. Otherwise return 0.
*/
static int walDecodeFrame(
  Wal *pWal,                      /* The write-ahead log */
  u32 *aCksum,                    /* IN/OUT: Checksum values */
  u32 *piPage,                    /* OUT: Database page number for frame */
  u32 *pnTruncate,                /* OUT: New db size (or 0 if not commit) */
  int nData,                      /* Database page size (size of aData[]) */
  u8 *aData,                      /* Pointer to page data (for checksum) */
  u8 *aFrame                      /* Frame data */
){

  assert( WAL_FRAME_HDRSIZE==24 );

#if 0



  if( pWal->nCkpt!=sqlite3Get4byte(&aFrame[8]) ){
    return 0;
  }
  if( pWal->iSalt1!=sqlite3Get4byte(&aFrame[12]) ){
    return 0;
  }
#endif




  walChecksumBytes(aFrame, 8, aCksum);
  walChecksumBytes(aData, nData, aCksum);
  if( aCksum[0]!=sqlite3Get4byte(&aFrame[16]) 
   || aCksum[1]!=sqlite3Get4byte(&aFrame[20]) 
  ){
    /* Checksum failed. */
    return 0;
  }




  *piPage = sqlite3Get4byte(&aFrame[0]);
  *pnTruncate = sqlite3Get4byte(&aFrame[4]);
  return 1;
}

/*
** Define the parameters of the hash tables in the wal-index file. There







|
>
>

|
<
<
|
<
<
|
|
|










|
|





<


<
|


>

<


|
<

|
|






>
>
|
<



<


<



>


<
>
>
>
|


<
<
|
<
|
>
>
>
|
|







>
>
>







346
347
348
349
350
351
352
353
354
355
356
357


358


359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378

379
380

381
382
383
384
385

386
387
388

389
390
391
392
393
394
395
396
397
398
399
400

401
402
403

404
405

406
407
408
409
410
411

412
413
414
415
416
417


418

419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
      pWal->lockState = SQLITE_SHM_READ;
    }
  }
  return rc;
}

/*
** Write the header information in pWal->hdr into the wal-index.
**
** The checksum on pWal->hdr is updated before it is written.
*/
static void walIndexWriteHdr(Wal *pWal){


  walChecksumBytes((u8*)&pWal->hdr,


                   sizeof(pWal->hdr) - sizeof(pWal->hdr.aCksum),
                   0, pWal->hdr.aCksum);
  memcpy((void*)pWal->pWiData, &pWal->hdr, sizeof(pWal->hdr));
}

/*
** This function encodes a single frame header and writes it to a buffer
** supplied by the caller. A frame-header is made up of a series of 
** 4-byte big-endian integers, as follows:
**
**     0: Page number.
**     4: For commit records, the size of the database image in pages 
**        after the commit. For all other records, zero.
**     8: Salt-1 (copied from the wal-header)
**    12: Salt-2 (copied from the wal-header)
**    16: Checksum-1.
**    20: Checksum-2.
*/
static void walEncodeFrame(
  Wal *pWal,                      /* The write-ahead log */

  u32 iPage,                      /* Database page number for frame */
  u32 nTruncate,                  /* New db size (or 0 for non-commit frames) */

  u8 *aData,                      /* Pointer to page data */
  u8 *aFrame                      /* OUT: Write encoded frame here */
){
  u32 aCksum[2];
  assert( WAL_FRAME_HDRSIZE==24 );

  sqlite3Put4byte(&aFrame[0], iPage);
  sqlite3Put4byte(&aFrame[4], nTruncate);
  memcpy(&aFrame[8], pWal->hdr.aSalt, 8);


  walChecksumBytes(aFrame, 16, 0, aCksum);
  walChecksumBytes(aData, pWal->szPage, aCksum, aCksum);

  sqlite3Put4byte(&aFrame[16], aCksum[0]);
  sqlite3Put4byte(&aFrame[20], aCksum[1]);
}

/*
** Check to see if the frame with header in aFrame[] and content
** in aData[] is valid.  If it is a valid frame, fill *piPage and
** *pnTruncate and return true.  Return if the frame is not valid.

*/
static int walDecodeFrame(
  Wal *pWal,                      /* The write-ahead log */

  u32 *piPage,                    /* OUT: Database page number for frame */
  u32 *pnTruncate,                /* OUT: New db size (or 0 if not commit) */

  u8 *aData,                      /* Pointer to page data (for checksum) */
  u8 *aFrame                      /* Frame data */
){
  u32 aCksum[2];
  assert( WAL_FRAME_HDRSIZE==24 );


  /* A frame is only valid if the salt values in the frame-header
  ** match the salt values in the wal-header. 
  */
  if( memcmp(&pWal->hdr.aSalt, &aFrame[8], 8)!=0 ){
    return 0;
  }




  /* A frame is only valid if a checksum of the first 16 bytes
  ** of the frame-header, and the frame-data matches
  ** the checksum in the last 8 bytes of the frame-header.
  */
  walChecksumBytes(aFrame, 16, 0, aCksum);
  walChecksumBytes(aData, pWal->szPage, aCksum, aCksum);
  if( aCksum[0]!=sqlite3Get4byte(&aFrame[16]) 
   || aCksum[1]!=sqlite3Get4byte(&aFrame[20]) 
  ){
    /* Checksum failed. */
    return 0;
  }

  /* If we reach this point, the frame is valid.  Return the page number
  ** and the new database size.
  */
  *piPage = sqlite3Get4byte(&aFrame[0]);
  *pnTruncate = sqlite3Get4byte(&aFrame[4]);
  return 1;
}

/*
** Define the parameters of the hash tables in the wal-index file. There
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667

668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718

719
720
721
722
723
724
725
    u8 aBuf[WAL_HDRSIZE];         /* Buffer to load first frame header into */
    u8 *aFrame = 0;               /* Malloc'd buffer to load entire frame */
    int szFrame;                  /* Number of bytes in buffer aFrame[] */
    u8 *aData;                    /* Pointer to data part of aFrame buffer */
    int iFrame;                   /* Index of last frame read */
    i64 iOffset;                  /* Next offset to read from log file */
    int szPage;                   /* Page size according to the log */
    u32 aCksum[2];                /* Running checksum */

    /* Read in the first frame header in the file (to determine the 
    ** database page size).
    */
    rc = sqlite3OsRead(pWal->pWalFd, aBuf, WAL_HDRSIZE, 0);
    if( rc!=SQLITE_OK ){
      return rc;
    }

    /* If the database page size is not a power of two, or is greater than
    ** SQLITE_MAX_PAGE_SIZE, conclude that the WAL file contains no valid data.
    */
    szPage = sqlite3Get4byte(&aBuf[8]);
    if( szPage&(szPage-1) || szPage>SQLITE_MAX_PAGE_SIZE || szPage<512 ){
      goto finished;
    }

    pWal->nCkpt = sqlite3Get4byte(&aBuf[12]);
    aCksum[0] = sqlite3Get4byte(&aBuf[16]);
    aCksum[1] = sqlite3Get4byte(&aBuf[20]);

    /* Malloc a buffer to read frames into. */
    szFrame = szPage + WAL_FRAME_HDRSIZE;
    aFrame = (u8 *)sqlite3_malloc(szFrame);
    if( !aFrame ){
      return SQLITE_NOMEM;
    }
    aData = &aFrame[WAL_FRAME_HDRSIZE];

    /* Read all frames from the log file. */
    iFrame = 0;
    for(iOffset=WAL_HDRSIZE; (iOffset+szFrame)<=nSize; iOffset+=szFrame){
      u32 pgno;                   /* Database page number for frame */
      u32 nTruncate;              /* dbsize field from frame header */
      int isValid;                /* True if this frame is valid */

      /* Read and decode the next log frame. */
      rc = sqlite3OsRead(pWal->pWalFd, aFrame, szFrame, iOffset);
      if( rc!=SQLITE_OK ) break;
      isValid = walDecodeFrame(pWal, aCksum, &pgno, &nTruncate, szPage,
                               aData, aFrame);
      if( !isValid ) break;
      rc = walIndexAppend(pWal, ++iFrame, pgno);
      if( rc!=SQLITE_OK ) break;

      /* If nTruncate is non-zero, this is a commit record. */
      if( nTruncate ){
        hdr.iCheck1 = aCksum[0];
        hdr.iCheck2 = aCksum[1];
        hdr.mxFrame = iFrame;
        hdr.nPage = nTruncate;
        hdr.szPage = szPage;
      }
    }

    sqlite3_free(aFrame);
  }else{
    hdr.iCheck1 = 2;
    hdr.iCheck2 = 3;
  }

finished:
  if( rc==SQLITE_OK && hdr.mxFrame==0 ){
    rc = walIndexRemap(pWal, WALINDEX_MMAP_INCREMENT);
  }
  if( rc==SQLITE_OK ){
    walIndexWriteHdr(pWal, &hdr);
    memcpy(&pWal->hdr, &hdr, sizeof(hdr));

  }
  return rc;
}

/*
** Close an open wal-index.
*/







<
















>

|
<



















|
<






<
<








|
<







<

>







671
672
673
674
675
676
677

678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696

697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716

717
718
719
720
721
722


723
724
725
726
727
728
729
730
731

732
733
734
735
736
737
738

739
740
741
742
743
744
745
746
747
    u8 aBuf[WAL_HDRSIZE];         /* Buffer to load first frame header into */
    u8 *aFrame = 0;               /* Malloc'd buffer to load entire frame */
    int szFrame;                  /* Number of bytes in buffer aFrame[] */
    u8 *aData;                    /* Pointer to data part of aFrame buffer */
    int iFrame;                   /* Index of last frame read */
    i64 iOffset;                  /* Next offset to read from log file */
    int szPage;                   /* Page size according to the log */


    /* Read in the first frame header in the file (to determine the 
    ** database page size).
    */
    rc = sqlite3OsRead(pWal->pWalFd, aBuf, WAL_HDRSIZE, 0);
    if( rc!=SQLITE_OK ){
      return rc;
    }

    /* If the database page size is not a power of two, or is greater than
    ** SQLITE_MAX_PAGE_SIZE, conclude that the WAL file contains no valid data.
    */
    szPage = sqlite3Get4byte(&aBuf[8]);
    if( szPage&(szPage-1) || szPage>SQLITE_MAX_PAGE_SIZE || szPage<512 ){
      goto finished;
    }
    pWal->szPage = szPage;
    pWal->nCkpt = sqlite3Get4byte(&aBuf[12]);
    memcpy(&pWal->hdr.aSalt, &aBuf[16], 8);


    /* Malloc a buffer to read frames into. */
    szFrame = szPage + WAL_FRAME_HDRSIZE;
    aFrame = (u8 *)sqlite3_malloc(szFrame);
    if( !aFrame ){
      return SQLITE_NOMEM;
    }
    aData = &aFrame[WAL_FRAME_HDRSIZE];

    /* Read all frames from the log file. */
    iFrame = 0;
    for(iOffset=WAL_HDRSIZE; (iOffset+szFrame)<=nSize; iOffset+=szFrame){
      u32 pgno;                   /* Database page number for frame */
      u32 nTruncate;              /* dbsize field from frame header */
      int isValid;                /* True if this frame is valid */

      /* Read and decode the next log frame. */
      rc = sqlite3OsRead(pWal->pWalFd, aFrame, szFrame, iOffset);
      if( rc!=SQLITE_OK ) break;
      isValid = walDecodeFrame(pWal, &pgno, &nTruncate, aData, aFrame);

      if( !isValid ) break;
      rc = walIndexAppend(pWal, ++iFrame, pgno);
      if( rc!=SQLITE_OK ) break;

      /* If nTruncate is non-zero, this is a commit record. */
      if( nTruncate ){


        hdr.mxFrame = iFrame;
        hdr.nPage = nTruncate;
        hdr.szPage = szPage;
      }
    }

    sqlite3_free(aFrame);
  }else{
    memset(&hdr, 0, sizeof(hdr));

  }

finished:
  if( rc==SQLITE_OK && hdr.mxFrame==0 ){
    rc = walIndexRemap(pWal, WALINDEX_MMAP_INCREMENT);
  }
  if( rc==SQLITE_OK ){

    memcpy(&pWal->hdr, &hdr, sizeof(hdr));
    walIndexWriteHdr(pWal);
  }
  return rc;
}

/*
** Close an open wal-index.
*/
770
771
772
773
774
775
776

777
778
779
780
781
782
783
  if( !pRet ){
    return SQLITE_NOMEM;
  }

  pRet->pVfs = pVfs;
  pRet->pWalFd = (sqlite3_file *)&pRet[1];
  pRet->pDbFd = pDbFd;

  pRet->zWalName = zWal = pVfs->szOsFile + (char*)pRet->pWalFd;
  sqlite3_snprintf(nWal, zWal, "%s-wal", zDbName);
  rc = sqlite3OsShmOpen(pDbFd);

  /* Open file handle on the write-ahead log file. */
  if( rc==SQLITE_OK ){
    pRet->isWindexOpen = 1;







>







792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
  if( !pRet ){
    return SQLITE_NOMEM;
  }

  pRet->pVfs = pVfs;
  pRet->pWalFd = (sqlite3_file *)&pRet[1];
  pRet->pDbFd = pDbFd;
  sqlite3_randomness(8, &pRet->hdr.aSalt);
  pRet->zWalName = zWal = pVfs->szOsFile + (char*)pRet->pWalFd;
  sqlite3_snprintf(nWal, zWal, "%s-wal", zDbName);
  rc = sqlite3OsShmOpen(pDbFd);

  /* Open file handle on the write-ahead log file. */
  if( rc==SQLITE_OK ){
    pRet->isWindexOpen = 1;
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060

  /* Sync the database file. If successful, update the wal-index. */
  if( sync_flags ){
    rc = sqlite3OsSync(pWal->pDbFd, sync_flags);
    if( rc!=SQLITE_OK ) goto out;
  }
  pWal->hdr.mxFrame = 0;
  pWal->hdr.iCheck1 = 2;
  pWal->hdr.iCheck2 = 3;
  walIndexWriteHdr(pWal, &pWal->hdr);
  pWal->nCkpt++;

  /* TODO: If a crash occurs and the current log is copied into the 
  ** database there is no problem. However, if a crash occurs while
  ** writing the next transaction into the start of the log, such that:
  **
  **   * The first transaction currently in the log is left intact, but
  **   * The second (or subsequent) transaction is damaged,
  **
  ** then the database could become corrupt.
  **
  ** The easiest thing to do would be to write and sync a dummy header
  ** into the log at this point. Unfortunately, that turns out to be
  ** an unwelcome performance hit. Alternatives are...
  */
#if 0 
  memset(zBuf, 0, WAL_FRAME_HDRSIZE);
  rc = sqlite3OsWrite(pWal->pWalFd, zBuf, WAL_FRAME_HDRSIZE, 0);
  if( rc!=SQLITE_OK ) goto out;
  rc = sqlite3OsSync(pWal->pWalFd, pWal->sync_flags);
#endif

 out:
  walIteratorFree(pIter);
  return rc;
}

/*







<
<
<

|
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
|
<
|
|







1046
1047
1048
1049
1050
1051
1052



1053
1054















1055

1056
1057
1058
1059
1060
1061
1062
1063
1064

  /* Sync the database file. If successful, update the wal-index. */
  if( sync_flags ){
    rc = sqlite3OsSync(pWal->pDbFd, sync_flags);
    if( rc!=SQLITE_OK ) goto out;
  }
  pWal->hdr.mxFrame = 0;



  pWal->nCkpt++;
  sqlite3Put4byte((u8*)pWal->hdr.aSalt,















                   1 + sqlite3Get4byte((u8*)pWal->hdr.aSalt));

  sqlite3_randomness(4, &pWal->hdr.aSalt[1]);
  walIndexWriteHdr(pWal);

 out:
  walIteratorFree(pIter);
  return rc;
}

/*
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149

1150
1151
1152
1153
1154
1155
1156
** pWal->hdr, then pWal->hdr is updated to the content of the new header
** and *pChanged is set to 1.
**
** If the checksum cannot be verified return non-zero. If the header
** is read successfully and the checksum verified, return zero.
*/
int walIndexTryHdr(Wal *pWal, int *pChanged){
  int i;
  volatile u32 *aWiData;
  u32 aCksum[2] = {1, 1};
  u32 aHdr[WALINDEX_HDR_NFIELD+2];

  assert( pWal->pWiData );
  if( pWal->szWIndex==0 ){
    /* The wal-index is of size 0 bytes. This is handled in the same way
    ** as an invalid header. The caller will run recovery to construct
    ** a valid wal-index file before accessing the database.
    */
    return 1;
  }

  /* Read the header. The caller may or may not have an exclusive 
  ** (WRITE, PENDING, CHECKPOINT or RECOVER) lock on the wal-index
  ** file, meaning it is possible that an inconsistent snapshot is read
  ** from the file. If this happens, return non-zero.
  */
  aWiData = pWal->pWiData;
  for(i=0; i<WALINDEX_HDR_NFIELD+2; i++){
    aHdr[i] = aWiData[i];
  }
  walChecksumBytes((u8*)aHdr, sizeof(u32)*WALINDEX_HDR_NFIELD, aCksum);
  if( aCksum[0]!=aHdr[WALINDEX_HDR_NFIELD]
   || aCksum[1]!=aHdr[WALINDEX_HDR_NFIELD+1]
  ){
    return 1;
  }

  if( memcmp(&pWal->hdr, aHdr, sizeof(WalIndexHdr)) ){
    *pChanged = 1;
    memcpy(&pWal->hdr, aHdr, sizeof(WalIndexHdr));

  }

  /* The header was successfully read. Return zero. */
  return 0;
}

/*







<
<
|
|















|
<
<
<
|
|
<
<



|

|
>







1114
1115
1116
1117
1118
1119
1120


1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138



1139
1140


1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
** pWal->hdr, then pWal->hdr is updated to the content of the new header
** and *pChanged is set to 1.
**
** If the checksum cannot be verified return non-zero. If the header
** is read successfully and the checksum verified, return zero.
*/
int walIndexTryHdr(Wal *pWal, int *pChanged){


  u32 aCksum[2];
  WalIndexHdr hdr;

  assert( pWal->pWiData );
  if( pWal->szWIndex==0 ){
    /* The wal-index is of size 0 bytes. This is handled in the same way
    ** as an invalid header. The caller will run recovery to construct
    ** a valid wal-index file before accessing the database.
    */
    return 1;
  }

  /* Read the header. The caller may or may not have an exclusive 
  ** (WRITE, PENDING, CHECKPOINT or RECOVER) lock on the wal-index
  ** file, meaning it is possible that an inconsistent snapshot is read
  ** from the file. If this happens, return non-zero.
  */
  memcpy(&hdr, (void*)pWal->pWiData, sizeof(hdr));



  walChecksumBytes((u8*)&hdr, sizeof(hdr)-sizeof(hdr.aCksum), 0, aCksum);
  if( aCksum[0]!=hdr.aCksum[0] || aCksum[1]!=hdr.aCksum[1] ){


    return 1;
  }

  if( memcmp(&pWal->hdr, &hdr, sizeof(WalIndexHdr)) ){
    *pChanged = 1;
    memcpy(&pWal->hdr, &hdr, sizeof(WalIndexHdr));
    pWal->szPage = pWal->hdr.szPage;
  }

  /* The header was successfully read. Return zero. */
  return 0;
}

/*
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537

1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
}

/* Move the write position of the WAL back to iFrame.  Called in
** response to a ROLLBACK TO command.
*/
int sqlite3WalSavepointUndo(Wal *pWal, u32 iFrame){
  int rc = SQLITE_OK;
  u8 aCksum[8];
  assert( pWal->lockState==SQLITE_SHM_WRITE );

  pWal->hdr.mxFrame = iFrame;
  if( iFrame>0 ){
    i64 iOffset = walFrameOffset(iFrame, pWal->hdr.szPage) + sizeof(u32)*4;
    rc = sqlite3OsRead(pWal->pWalFd, aCksum, sizeof(aCksum), iOffset);
    pWal->hdr.iCheck1 = sqlite3Get4byte(&aCksum[0]);
    pWal->hdr.iCheck2 = sqlite3Get4byte(&aCksum[4]);
  }

  return rc;
}

/* 
** Write a set of frames to the log. The caller must hold the write-lock
** on the log file (obtained using sqlite3WalWriteLock()).
*/
int sqlite3WalFrames(
  Wal *pWal,                      /* Wal handle to write to */
  int szPage,                     /* Database page-size in bytes */
  PgHdr *pList,                   /* List of dirty pages to write */
  Pgno nTruncate,                 /* Database size after this commit */
  int isCommit,                   /* True if this is a commit */
  int sync_flags                  /* Flags to pass to OsSync() (or 0) */
){
  int rc;                         /* Used to catch return codes */
  u32 iFrame;                     /* Next frame address */
  u8 aFrame[WAL_FRAME_HDRSIZE];   /* Buffer to assemble frame-header in */
  PgHdr *p;                       /* Iterator to run through pList with. */
  u32 aCksum[2];                  /* Checksums */
  PgHdr *pLast = 0;               /* Last frame in list */
  int nLast = 0;                  /* Number of extra copies of last page */

  assert( pList );
  assert( pWal->lockState==SQLITE_SHM_WRITE );
  assert( pWal->pWiData==0 );

  /* If this is the first frame written into the log, write the WAL
  ** header to the start of the WAL file. See comments at the top of
  ** this source file for a description of the WAL header format.
  */
  iFrame = pWal->hdr.mxFrame;
  if( iFrame==0 ){
    u8 aWalHdr[WAL_HDRSIZE];        /* Buffer to assembly wal-header in */
    sqlite3Put4byte(&aWalHdr[0], 0x377f0682);
    sqlite3Put4byte(&aWalHdr[4], 3007000);
    sqlite3Put4byte(&aWalHdr[8], szPage);

    sqlite3Put4byte(&aWalHdr[12], pWal->nCkpt);
    sqlite3_randomness(8, &aWalHdr[16]);
    pWal->hdr.iCheck1 = pWal->iSalt1 = sqlite3Get4byte(&aWalHdr[16]);
    pWal->hdr.iCheck2 = pWal->iSalt2 = sqlite3Get4byte(&aWalHdr[20]);
    rc = sqlite3OsWrite(pWal->pWalFd, aWalHdr, sizeof(aWalHdr), 0);
    if( rc!=SQLITE_OK ){
      return rc;
    }
  }

  aCksum[0] = pWal->hdr.iCheck1;
  aCksum[1] = pWal->hdr.iCheck2;

  /* Write the log file. */
  for(p=pList; p; p=p->pDirty){
    u32 nDbsize;                  /* Db-size field for frame header */
    i64 iOffset;                  /* Write offset in log file */

    iOffset = walFrameOffset(++iFrame, szPage);
    
    /* Populate and write the frame header */
    nDbsize = (isCommit && p->pDirty==0) ? nTruncate : 0;
    walEncodeFrame(pWal, aCksum, p->pgno, nDbsize, szPage, p->pData, aFrame);
    rc = sqlite3OsWrite(pWal->pWalFd, aFrame, sizeof(aFrame), iOffset);
    if( rc!=SQLITE_OK ){
      return rc;
    }

    /* Write the page data */
    rc = sqlite3OsWrite(pWal->pWalFd, p->pData, szPage, iOffset+sizeof(aFrame));







<



<
<
<
<
<
<
<



















<

















>

|
<
<





|
<
<

|








|







1481
1482
1483
1484
1485
1486
1487

1488
1489
1490







1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509

1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529


1530
1531
1532
1533
1534
1535


1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
}

/* Move the write position of the WAL back to iFrame.  Called in
** response to a ROLLBACK TO command.
*/
int sqlite3WalSavepointUndo(Wal *pWal, u32 iFrame){
  int rc = SQLITE_OK;

  assert( pWal->lockState==SQLITE_SHM_WRITE );

  pWal->hdr.mxFrame = iFrame;







  return rc;
}

/* 
** Write a set of frames to the log. The caller must hold the write-lock
** on the log file (obtained using sqlite3WalWriteLock()).
*/
int sqlite3WalFrames(
  Wal *pWal,                      /* Wal handle to write to */
  int szPage,                     /* Database page-size in bytes */
  PgHdr *pList,                   /* List of dirty pages to write */
  Pgno nTruncate,                 /* Database size after this commit */
  int isCommit,                   /* True if this is a commit */
  int sync_flags                  /* Flags to pass to OsSync() (or 0) */
){
  int rc;                         /* Used to catch return codes */
  u32 iFrame;                     /* Next frame address */
  u8 aFrame[WAL_FRAME_HDRSIZE];   /* Buffer to assemble frame-header in */
  PgHdr *p;                       /* Iterator to run through pList with. */

  PgHdr *pLast = 0;               /* Last frame in list */
  int nLast = 0;                  /* Number of extra copies of last page */

  assert( pList );
  assert( pWal->lockState==SQLITE_SHM_WRITE );
  assert( pWal->pWiData==0 );

  /* If this is the first frame written into the log, write the WAL
  ** header to the start of the WAL file. See comments at the top of
  ** this source file for a description of the WAL header format.
  */
  iFrame = pWal->hdr.mxFrame;
  if( iFrame==0 ){
    u8 aWalHdr[WAL_HDRSIZE];        /* Buffer to assembly wal-header in */
    sqlite3Put4byte(&aWalHdr[0], 0x377f0682);
    sqlite3Put4byte(&aWalHdr[4], 3007000);
    sqlite3Put4byte(&aWalHdr[8], szPage);
    pWal->szPage = szPage;
    sqlite3Put4byte(&aWalHdr[12], pWal->nCkpt);
    memcpy(&aWalHdr[16], pWal->hdr.aSalt, 8);


    rc = sqlite3OsWrite(pWal->pWalFd, aWalHdr, sizeof(aWalHdr), 0);
    if( rc!=SQLITE_OK ){
      return rc;
    }
  }
  assert( pWal->szPage==szPage );



    /* Write the log file. */
  for(p=pList; p; p=p->pDirty){
    u32 nDbsize;                  /* Db-size field for frame header */
    i64 iOffset;                  /* Write offset in log file */

    iOffset = walFrameOffset(++iFrame, szPage);
    
    /* Populate and write the frame header */
    nDbsize = (isCommit && p->pDirty==0) ? nTruncate : 0;
    walEncodeFrame(pWal, p->pgno, nDbsize, p->pData, aFrame);
    rc = sqlite3OsWrite(pWal->pWalFd, aFrame, sizeof(aFrame), iOffset);
    if( rc!=SQLITE_OK ){
      return rc;
    }

    /* Write the page data */
    rc = sqlite3OsWrite(pWal->pWalFd, p->pData, szPage, iOffset+sizeof(aFrame));
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
    i64 iOffset = walFrameOffset(iFrame+1, szPage);

    assert( isCommit );
    assert( iSegment>0 );

    iSegment = (((iOffset+iSegment-1)/iSegment) * iSegment);
    while( iOffset<iSegment ){
      walEncodeFrame(pWal, aCksum, pLast->pgno, nTruncate, szPage,
                     pLast->pData, aFrame);
      rc = sqlite3OsWrite(pWal->pWalFd, aFrame, sizeof(aFrame), iOffset);
      if( rc!=SQLITE_OK ){
        return rc;
      }

      iOffset += WAL_FRAME_HDRSIZE;
      rc = sqlite3OsWrite(pWal->pWalFd, pLast->pData, szPage, iOffset); 







|
<







1563
1564
1565
1566
1567
1568
1569
1570

1571
1572
1573
1574
1575
1576
1577
    i64 iOffset = walFrameOffset(iFrame+1, szPage);

    assert( isCommit );
    assert( iSegment>0 );

    iSegment = (((iOffset+iSegment-1)/iSegment) * iSegment);
    while( iOffset<iSegment ){
      walEncodeFrame(pWal, pLast->pgno, nTruncate, pLast->pData, aFrame);

      rc = sqlite3OsWrite(pWal->pWalFd, aFrame, sizeof(aFrame), iOffset);
      if( rc!=SQLITE_OK ){
        return rc;
      }

      iOffset += WAL_FRAME_HDRSIZE;
      rc = sqlite3OsWrite(pWal->pWalFd, pLast->pData, szPage, iOffset); 
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
    /* Update the private copy of the header. */
    pWal->hdr.szPage = szPage;
    pWal->hdr.mxFrame = iFrame;
    if( isCommit ){
      pWal->hdr.iChange++;
      pWal->hdr.nPage = nTruncate;
    }
    pWal->hdr.iCheck1 = aCksum[0];
    pWal->hdr.iCheck2 = aCksum[1];

    /* If this is a commit, update the wal-index header too. */
    if( isCommit ){
      walIndexWriteHdr(pWal, &pWal->hdr);
      pWal->iCallback = iFrame;
    }
  }

  walIndexUnmap(pWal);
  return rc;
}







<
<
<


|







1606
1607
1608
1609
1610
1611
1612



1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
    /* Update the private copy of the header. */
    pWal->hdr.szPage = szPage;
    pWal->hdr.mxFrame = iFrame;
    if( isCommit ){
      pWal->hdr.iChange++;
      pWal->hdr.nPage = nTruncate;
    }



    /* If this is a commit, update the wal-index header too. */
    if( isCommit ){
      walIndexWriteHdr(pWal);
      pWal->iCallback = iFrame;
    }
  }

  walIndexUnmap(pWal);
  return rc;
}
Changes to test/wal.test.
552
553
554
555
556
557
558
559



560
561
562
563
564
565
566
    execsql { BEGIN ; SELECT * FROM t1 }
  } {1 2 3 4 5 6}
  do_test wal-10.$tn.9 {
    sql2 COMMIT
    catchsql { INSERT INTO t1 VALUES(9, 10) }
  } {1 {database is locked}}
  do_test wal-10.$tn.10 {
    execsql { COMMIT; BEGIN; INSERT INTO t1 VALUES(9, 10); COMMIT; }



    execsql { SELECT * FROM t1 }
  } {1 2 3 4 5 6 7 8 9 10}

  # Open a read transaction with [db2]. Check that this prevents [db] from
  # checkpointing the database. But not from writing to it.
  #
  do_test wal-10.$tn.11 {







|
>
>
>







552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
    execsql { BEGIN ; SELECT * FROM t1 }
  } {1 2 3 4 5 6}
  do_test wal-10.$tn.9 {
    sql2 COMMIT
    catchsql { INSERT INTO t1 VALUES(9, 10) }
  } {1 {database is locked}}
  do_test wal-10.$tn.10 {
    execsql { COMMIT }
    execsql { BEGIN }
    execsql { INSERT INTO t1 VALUES(9, 10) }
    execsql { COMMIT }
    execsql { SELECT * FROM t1 }
  } {1 2 3 4 5 6 7 8 9 10}

  # Open a read transaction with [db2]. Check that this prevents [db] from
  # checkpointing the database. But not from writing to it.
  #
  do_test wal-10.$tn.11 {
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344


1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
      # The page-size in the log file header is set to $pgsz. If the
      # WAL code considers $pgsz to be a valid SQLite database file page-size,
      # the database will be corrupt (because the garbage frame contents
      # will be treated as valid content). If $pgsz is invalid (too small
      # or too large), the db will not be corrupt as the log file will
      # be ignored.
      #
      set c1 22
      set c2 23
      set walhdr [binary format IIIIII 931071618 3007000 $pgsz 1234 $c1 $c2]
      set salt1 $c1
      set framebody [randomblob $pgsz]
      set framehdr  [binary format II $pg 5]


      logcksum c1 c2 $framehdr
      logcksum c1 c2 $framebody
      set framehdr [binary format IIIIII $pg 5 1234 $salt1 $c1 $c2]
      set fd [open test.db-wal w]
      fconfigure $fd -encoding binary -translation binary
      puts -nonewline $fd $walhdr
      puts -nonewline $fd $framehdr
      puts -nonewline $fd $framebody
      close $fd
  







<
<
|
<

|
>
>


|







1335
1336
1337
1338
1339
1340
1341


1342

1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
      # The page-size in the log file header is set to $pgsz. If the
      # WAL code considers $pgsz to be a valid SQLite database file page-size,
      # the database will be corrupt (because the garbage frame contents
      # will be treated as valid content). If $pgsz is invalid (too small
      # or too large), the db will not be corrupt as the log file will
      # be ignored.
      #


      set walhdr [binary format IIIIII 931071618 3007000 $pgsz 1234 22 23]

      set framebody [randomblob $pgsz]
      set framehdr  [binary format IIII $pg 5 22 23]
      set c1 0
      set c2 0
      logcksum c1 c2 $framehdr
      logcksum c1 c2 $framebody
      set framehdr [binary format IIIIII $pg 5 22 23 $c1 $c2]
      set fd [open test.db-wal w]
      fconfigure $fd -encoding binary -translation binary
      puts -nonewline $fd $walhdr
      puts -nonewline $fd $framehdr
      puts -nonewline $fd $framebody
      close $fd
  
Changes to test/wal2.test.
111
112
113
114
115
116
117

118
119
120
121
122
123
124
        }
      }

      if {$method == "xShmLock"} { lappend ::locks [lindex $args 2] }
      return SQLITE_OK
    }


    execsql { SELECT count(a), sum(a) FROM t1 } db2
  } $res

  do_test wal2-1.$tn.2 {
    set ::locks
  } $wal_locks
}







>







111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
        }
      }

      if {$method == "xShmLock"} { lappend ::locks [lindex $args 2] }
      return SQLITE_OK
    }

breakpoint
    execsql { SELECT count(a), sum(a) FROM t1 } db2
  } $res

  do_test wal2-1.$tn.2 {
    set ::locks
  } $wal_locks
}
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
         4    7   {6 21}   {7 28}    2
         5    8   {7 28}   {8 36}    3
         6    9   {8 36}   {9 45}    4
         7   10   {9 45}   {10 55}   5
         8   11   {10 55}  {11 66}   6
         9   12   {11 66}  {12 78}   7
} {
  do_test wal2-1.$tn.1 {
    set oldhdr [set_tvfs_hdr $::shm_file]
    execsql { INSERT INTO t1 VALUES($iInsert) }
    execsql { SELECT count(a), sum(a) FROM t1 }
  } $res1

  do_test wal2-2.$tn.2 {
    set ::locks [list]







|







175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
         4    7   {6 21}   {7 28}    2
         5    8   {7 28}   {8 36}    3
         6    9   {8 36}   {9 45}    4
         7   10   {9 45}   {10 55}   5
         8   11   {10 55}  {11 66}   6
         9   12   {11 66}  {12 78}   7
} {
  do_test wal2-2.$tn.1 {
    set oldhdr [set_tvfs_hdr $::shm_file]
    execsql { INSERT INTO t1 VALUES($iInsert) }
    execsql { SELECT count(a), sum(a) FROM t1 }
  } $res1

  do_test wal2-2.$tn.2 {
    set ::locks [list]
599
600
601
602
603
604
605
606
do_test wal2-6.5.3 {
  execsql { PRAGMA wal_checkpoint }
} {}

db close

finish_test








<
600
601
602
603
604
605
606

do_test wal2-6.5.3 {
  execsql { PRAGMA wal_checkpoint }
} {}

db close

finish_test