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Fix the hash signature algorithm in vfslog.c. Add a utility program to

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show the hash signatures for every page of a database file.

FossilOrigin-Name: eaf4de13a63b2294ae575432a022493308a4313a
This commit is contained in:
drh
2013-10-10 13:38:51 +00:00
parent 30e2f0ae08
commit 7cd84ffc60
4 changed files with 117 additions and 19 deletions
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27
ext/misc/vfslog.c
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@ -307,21 +307,28 @@ static int vlogClose(sqlite3_file *pFile){
/*
** Compute signature for a block of content.
**
** The signature is a hex dump of the first 8 bytes of the block
** followed by a 64bit hash (expressed in hex) of the entire content.
** For blocks of 16 or fewer bytes, the signature is just a hex dump of
** the entire block.
**
** For blocks of more than 16 bytes, the signature is a hex dump of the
** first 8 bytes followed by a 64-bit has of the entire block.
*/
static void vlogSignature(unsigned char *p, int n, char *zCksum){
unsigned int s0 = 0, s1 = 0;
unsigned int *pI;
int i;
pI = (unsigned int*)p;
for(i=0; i<n-7; i+=8){
s0 += pI[0] + s1;
s1 += pI[1] + s0;
pI += 2;
if( n<=16 ){
for(i=0; i<n; i++) sqlite3_snprintf(3, zCksum+i*2, "%02x", p[i]);
}else{
pI = (unsigned int*)p;
for(i=0; i<n-7; i+=8){
s0 += pI[0] + s1;
s1 += pI[1] + s0;
pI += 2;
}
for(i=0; i<8; i++) sqlite3_snprintf(3, zCksum+i*2, "%02x", p[i]);
sqlite3_snprintf(18, zCksum+i*2, "-%08x08x", s0, s1);
}
for(i=0; i<8 && i<n; i++) sqlite3_snprintf(3, zCksum+i, "%02x", p[i]);
if( n>8 ) sqlite3_snprintf(18, zCksum+i, "-%08x08x", s0, s1);
}
/*
@ -660,5 +667,3 @@ int sqlite3_register_vfslog(const char *zArg){
vlog_vfs.base.szOsFile = sizeof(VLogFile) + vlog_vfs.pVfs->szOsFile;
return sqlite3_vfs_register(&vlog_vfs.base, 1);
}