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Improvements to corrupt database detection in defragmentPage(). (CVS 6857)

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FossilOrigin-Name: 87bbc8d6b68c089c8211c35c11c2f6ac4e46271c
This commit is contained in:
drh
2009-07-07 17:38:38 +00:00
parent 172114a02e
commit 1714662877
3 changed files with 32 additions and 17 deletions
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33
src/btree.c
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@@ -9,7 +9,7 @@
** May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.656 2009/07/07 15:47:12 danielk1977 Exp $
** $Id: btree.c,v 1.657 2009/07/07 17:38:39 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
@@ -1005,7 +1005,6 @@ static int ptrmapPutOvflPtr(MemPage *pPage, u8 *pCell){
static int defragmentPage(MemPage *pPage){
int i; /* Loop counter */
int pc; /* Address of a i-th cell */
int addr; /* Offset of first byte after cell pointer array */
int hdr; /* Offset to the page header */
int size; /* Size of a cell */
int usableSize; /* Number of usable bytes on a page */
@@ -1014,6 +1013,9 @@ static int defragmentPage(MemPage *pPage){
int nCell; /* Number of cells on the page */
unsigned char *data; /* The page data */
unsigned char *temp; /* Temp area for cell content */
int iCellFirst; /* First allowable cell index */
int iCellLast; /* Last possible cell index */
assert( sqlite3PagerIswriteable(pPage->pDbPage) );
assert( pPage->pBt!=0 );
@@ -1030,31 +1032,44 @@ static int defragmentPage(MemPage *pPage){
cbrk = get2byte(&data[hdr+5]);
memcpy(&temp[cbrk], &data[cbrk], usableSize - cbrk);
cbrk = usableSize;
iCellFirst = cellOffset + 2*nCell;
iCellLast = usableSize - 4;
for(i=0; i<nCell; i++){
u8 *pAddr; /* The i-th cell pointer */
pAddr = &data[cellOffset + i*2];
pc = get2byte(pAddr);
if( pc>=usableSize ){
#if !defined(SQLITE_ENABLE_OVERSIZE_CELL_CHECK)
/* These conditions have already been verified in sqlite3BtreeInitPage()
** if SQLITE_ENABLE_OVERSIZE_CELL_CHECK is defined
*/
if( pc<iCellFirst || pc>iCellLast ){
return SQLITE_CORRUPT_BKPT;
}
#endif
assert( pc>=iCellFirst && pc<=iCellLast );
size = cellSizePtr(pPage, &temp[pc]);
cbrk -= size;
if( cbrk<cellOffset+2*nCell || pc+size>usableSize ){
#if defined(SQLITE_ENABLE_OVERSIZE_CELL_CHECK)
if( cbrk<iCellFirst ){
return SQLITE_CORRUPT_BKPT;
}
assert( cbrk+size<=usableSize && cbrk>=0 );
#else
if( cbrk<iCellFirst || pc+size>usableSize ){
return SQLITE_CORRUPT_BKPT;
}
#endif
assert( cbrk+size<=usableSize && cbrk>iCellFirst );
memcpy(&data[cbrk], &temp[pc], size);
put2byte(pAddr, cbrk);
}
assert( cbrk>=cellOffset+2*nCell );
assert( cbrk>=iCellFirst );
put2byte(&data[hdr+5], cbrk);
data[hdr+1] = 0;
data[hdr+2] = 0;
data[hdr+7] = 0;
addr = cellOffset+2*nCell;
memset(&data[addr], 0, cbrk-addr);
memset(&data[iCellFirst], 0, cbrk-iCellFirst);
assert( sqlite3PagerIswriteable(pPage->pDbPage) );
if( cbrk-addr!=pPage->nFree ){
if( cbrk-iCellFirst!=pPage->nFree ){
return SQLITE_CORRUPT_BKPT;
}
return SQLITE_OK;