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Overview
| Comment: | Add an "isInit" field in the wal-index header that must be non-zero for a valid header. Use this to detect an uninitialized wal-index. |
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| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | wal-incr-ckpt |
| Files: | files | file ages | folders |
| SHA1: |
a16fde190183d1ae252d1aa305b23fdb |
| User & Date: | drh 2010-05-31 18:24:19.000 |
Context
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2010-05-31
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| 20:28 | Fix issues with locking_mode=EXCLUSIVE in WAL. (check-in: 8deba0cebd user: drh tags: wal-incr-ckpt) | |
| 18:24 | Add an "isInit" field in the wal-index header that must be non-zero for a valid header. Use this to detect an uninitialized wal-index. (check-in: a16fde1901 user: drh tags: wal-incr-ckpt) | |
| 16:56 | Fix an inconsistent #ifdef in wal.c. Fix os_unix.c so that it does not allow moving an SHM lock directly exclusive to shared without going through unlocked. (check-in: 552658da28 user: drh tags: wal-incr-ckpt) | |
Changes
Changes to src/wal.c.
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** The following object holds a copy of the wal-index header content.
**
** The actual header in the wal-index consists of two copies of this
** object.
*/
struct WalIndexHdr {
u32 iChange; /* Counter incremented each transaction */
| > | | 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 |
** The following object holds a copy of the wal-index header content.
**
** The actual header in the wal-index consists of two copies of this
** object.
*/
struct WalIndexHdr {
u32 iChange; /* Counter incremented each transaction */
u8 isInit; /* 1 when initialized */
u8 bigEndCksum; /* True if checksums in WAL are big-endian */
u16 szPage; /* Database page size in bytes */
u32 mxFrame; /* Index of last valid frame in the WAL */
u32 nPage; /* Size of database in pages */
u32 aFrameCksum[2]; /* Checksum of last frame in log */
u32 aSalt[2]; /* Two salt values copied from WAL header */
u32 aCksum[2]; /* Checksum over all prior fields */
};
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**
** The checksum on pWal->hdr is updated before it is written.
*/
static void walIndexWriteHdr(Wal *pWal){
WalIndexHdr *aHdr;
assert( pWal->writeLock );
walChecksumBytes(1, (u8*)&pWal->hdr, offsetof(WalIndexHdr, aCksum),
0, pWal->hdr.aCksum);
aHdr = (WalIndexHdr*)pWal->pWiData;
memcpy(&aHdr[1], &pWal->hdr, sizeof(WalIndexHdr));
sqlite3OsShmBarrier(pWal->pDbFd);
memcpy(&aHdr[0], &pWal->hdr, sizeof(WalIndexHdr));
}
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**
** The checksum on pWal->hdr is updated before it is written.
*/
static void walIndexWriteHdr(Wal *pWal){
WalIndexHdr *aHdr;
assert( pWal->writeLock );
pWal->hdr.isInit = 1;
walChecksumBytes(1, (u8*)&pWal->hdr, offsetof(WalIndexHdr, aCksum),
0, pWal->hdr.aCksum);
aHdr = (WalIndexHdr*)pWal->pWiData;
memcpy(&aHdr[1], &pWal->hdr, sizeof(WalIndexHdr));
sqlite3OsShmBarrier(pWal->pDbFd);
memcpy(&aHdr[0], &pWal->hdr, sizeof(WalIndexHdr));
}
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memcpy(&h1, &aHdr[0], sizeof(h1));
sqlite3OsShmBarrier(pWal->pDbFd);
memcpy(&h2, &aHdr[1], sizeof(h2));
if( memcmp(&h1, &h2, sizeof(h1))!=0 ){
return 1; /* Dirty read */
}
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memcpy(&h1, &aHdr[0], sizeof(h1));
sqlite3OsShmBarrier(pWal->pDbFd);
memcpy(&h2, &aHdr[1], sizeof(h2));
if( memcmp(&h1, &h2, sizeof(h1))!=0 ){
return 1; /* Dirty read */
}
if( h1.isInit==0 ){
return 1; /* Malformed header - probably all zeros */
}
walChecksumBytes(1, (u8*)&h1, sizeof(h1)-sizeof(h1.aCksum), 0, aCksum);
if( aCksum[0]!=h1.aCksum[0] || aCksum[1]!=h1.aCksum[1] ){
return 1; /* Checksum does not match */
}
if( memcmp(&pWal->hdr, &h1, sizeof(WalIndexHdr)) ){
*pChanged = 1;
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