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Overview
| Comment: | Enhanced detection of database corruption in btree.c:allocateSpace(). |
|---|---|
| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
5a511f98877f0f7f12d336b7831f3da9 |
| User & Date: | drh 2009-12-06 03:35:51.000 |
Context
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2009-12-07
| ||
| 12:34 | Add some tests for OR, AND and NOT operations to fts3rnd.test. Add tests to check that errors are returned when bad arguments are passed to fts3 functions snippet, offsets and optimize. Minor fix for the same (check-in: 5811df3f04 user: dan tags: trunk) | |
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2009-12-06
| ||
| 03:35 | Enhanced detection of database corruption in btree.c:allocateSpace(). (check-in: 5a511f9887 user: drh tags: trunk) | |
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2009-12-05
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| 18:34 | Fix to check-in [f221f31eff]: Make sure local variable rc is declared even when compiled without SQLITE_DEBUG. (check-in: 7a9a35327c user: drh tags: trunk) | |
Changes
Changes to src/btree.c.
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static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){
const int hdr = pPage->hdrOffset; /* Local cache of pPage->hdrOffset */
u8 * const data = pPage->aData; /* Local cache of pPage->aData */
int nFrag; /* Number of fragmented bytes on pPage */
int top; /* First byte of cell content area */
int gap; /* First byte of gap between cell pointers and cell content */
int rc; /* Integer return code */
assert( sqlite3PagerIswriteable(pPage->pDbPage) );
assert( pPage->pBt );
assert( sqlite3_mutex_held(pPage->pBt->mutex) );
assert( nByte>=0 ); /* Minimum cell size is 4 */
assert( pPage->nFree>=nByte );
assert( pPage->nOverflow==0 );
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static int allocateSpace(MemPage *pPage, int nByte, int *pIdx){
const int hdr = pPage->hdrOffset; /* Local cache of pPage->hdrOffset */
u8 * const data = pPage->aData; /* Local cache of pPage->aData */
int nFrag; /* Number of fragmented bytes on pPage */
int top; /* First byte of cell content area */
int gap; /* First byte of gap between cell pointers and cell content */
int rc; /* Integer return code */
int usableSize; /* Usable size of the page */
assert( sqlite3PagerIswriteable(pPage->pDbPage) );
assert( pPage->pBt );
assert( sqlite3_mutex_held(pPage->pBt->mutex) );
assert( nByte>=0 ); /* Minimum cell size is 4 */
assert( pPage->nFree>=nByte );
assert( pPage->nOverflow==0 );
usableSize = pPage->pBt->usableSize;
assert( nByte < usableSize-8 );
nFrag = data[hdr+7];
assert( pPage->cellOffset == hdr + 12 - 4*pPage->leaf );
gap = pPage->cellOffset + 2*pPage->nCell;
top = get2byte(&data[hdr+5]);
if( gap>top ) return SQLITE_CORRUPT_BKPT;
testcase( gap+2==top );
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}else if( gap+2<=top ){
/* Search the freelist looking for a free slot big enough to satisfy
** the request. The allocation is made from the first free slot in
** the list that is large enough to accomadate it.
*/
int pc, addr;
for(addr=hdr+1; (pc = get2byte(&data[addr]))>0; addr=pc){
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}else if( gap+2<=top ){
/* Search the freelist looking for a free slot big enough to satisfy
** the request. The allocation is made from the first free slot in
** the list that is large enough to accomadate it.
*/
int pc, addr;
for(addr=hdr+1; (pc = get2byte(&data[addr]))>0; addr=pc){
int size; /* Size of the free slot */
if( pc>usableSize-4 || pc<addr+4 ){
return SQLITE_CORRUPT_BKPT;
}
size = get2byte(&data[pc+2]);
if( size>=nByte ){
int x = size - nByte;
testcase( x==4 );
testcase( x==3 );
if( x<4 ){
/* Remove the slot from the free-list. Update the number of
** fragmented bytes within the page. */
memcpy(&data[addr], &data[pc], 2);
data[hdr+7] = (u8)(nFrag + x);
}else if( size+pc > usableSize ){
return SQLITE_CORRUPT_BKPT;
}else{
/* The slot remains on the free-list. Reduce its size to account
** for the portion used by the new allocation. */
put2byte(&data[pc+2], x);
}
*pIdx = pc + x;
return SQLITE_OK;
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