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Add an "isInit" field in the wal-index header that must be non-zero for

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a valid header.  Use this to detect an uninitialized wal-index.

FossilOrigin-Name: a16fde190183d1ae252d1aa305b23fdb88c603dc
This commit is contained in:
drh
2010-05-31 18:24:19 +00:00
parent 15d6809222
commit 4b82c387c9
3 changed files with 14 additions and 14 deletions
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8
src/wal.c
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@@ -260,7 +260,8 @@ typedef struct WalCkptInfo WalCkptInfo;
*/
struct WalIndexHdr {
u32 iChange; /* Counter incremented each transaction */
u16 bigEndCksum; /* True if checksums in WAL are big-endian */
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 */
@@ -481,6 +482,7 @@ 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;
@@ -1563,11 +1565,9 @@ int walIndexTryHdr(Wal *pWal, int *pChanged){
if( memcmp(&h1, &h2, sizeof(h1))!=0 ){
return 1; /* Dirty read */
}
#if 0
if( h1.szPage==0 ){
if( h1.isInit==0 ){
return 1; /* Malformed header - probably all zeros */
}
#endif
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 */