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Ensure randomly generated rowids never go negative.

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FossilOrigin-Name: 631423677bd7043e99987edc633005443125181c
This commit is contained in:
shaneh
2010-09-01 02:37:56 +00:00
parent c311feec55
commit c4d340a096
3 changed files with 22 additions and 16 deletions
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22
src/vdbe.c
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@@ -3719,18 +3719,24 @@ case OP_NewRowid: { /* out2-prerelease */
*/
assert( pOp->p3==0 ); /* We cannot be in random rowid mode if this is
** an AUTOINCREMENT table. */
/* on the first attempt, simply do one more than previous */
v = db->lastRowid;
v &= (MAX_ROWID>>1); /* ensure doesn't go negative */
v++; /* ensure non-zero */
cnt = 0;
do{
if( cnt==0 && (v&0xffffff)==v ){
v++;
while( ((rc = sqlite3BtreeMovetoUnpacked(pC->pCursor, 0, (u64)v, 0, &res))==SQLITE_OK)
&& (res==0)
&& (++cnt<100)){
/* collision - try another random rowid */
sqlite3_randomness(sizeof(v), &v);
if( cnt<5 ){
/* try "small" random rowids for the initial attempts */
v &= 0xffffff;
}else{
sqlite3_randomness(sizeof(v), &v);
if( cnt<5 ) v &= 0xffffff;
v &= (MAX_ROWID>>1); /* ensure doesn't go negative */
}
rc = sqlite3BtreeMovetoUnpacked(pC->pCursor, 0, (u64)v, 0, &res);
cnt++;
}while( cnt<100 && rc==SQLITE_OK && res==0 );
v++; /* ensure non-zero */
}
if( rc==SQLITE_OK && res==0 ){
rc = SQLITE_FULL; /* IMP: R-38219-53002 */
goto abort_due_to_error;