/*
* Returns:
* 0 OK
* -1 error
*/
int
__delpair(HTAB *hashp, BUFHEAD *bufp, int ndx)
{
u_int16_t *bp, newoff, pairlen;
int n;
bp = (u_int16_t *)bufp->page;
n = bp[0];
if (bp[ndx + 1] < REAL_KEY)
return (__big_delete(hashp, bufp));
if (ndx != 1)
newoff = bp[ndx - 1];
else
newoff = hashp->BSIZE;
pairlen = newoff - bp[ndx + 1];
if (ndx != (n - 1)) {
/* Hard Case -- need to shuffle keys */
int i;
char *src = bufp->page + (int)OFFSET(bp);
char *dst = src + (int)pairlen;
memmove(dst, src, bp[ndx + 1] - OFFSET(bp));
/* Now adjust the pointers */
for (i = ndx + 2; i <= n; i += 2) {
if (bp[i + 1] == OVFLPAGE) {
bp[i - 2] = bp[i];
bp[i - 1] = bp[i + 1];
} else {
bp[i - 2] = bp[i] + pairlen;
bp[i - 1] = bp[i + 1] + pairlen;
}
}
if (ndx == hashp->cndx) {
/*
* We just removed pair we were "pointing" to.
* By moving back the cndx we ensure subsequent
* hash_seq() calls won't skip over any entries.
*/
hashp->cndx -= 2;
}
}
/* Finally adjust the page data */
bp[n] = OFFSET(bp) + pairlen;
bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(u_int16_t);
bp[0] = n - 2;
hashp->NKEYS--;
bufp->flags |= BUF_MOD;
return (0);
}
/*
* Returns:
* 0 OK
* -1 error
*/
int
__delpair(HTAB *hashp, BUFHEAD *bufp, int ndx)
{
uint16_t *bp, newoff;
int n;
uint16_t pairlen;
size_t temp;
bp = (uint16_t *)(void *)bufp->page;
n = bp[0];
if (bp[ndx + 1] < REAL_KEY)
return (__big_delete(hashp, bufp));
if (ndx != 1)
newoff = bp[ndx - 1];
else
newoff = hashp->BSIZE;
pairlen = newoff - bp[ndx + 1];
if (ndx != (n - 1)) {
/* Hard Case -- need to shuffle keys */
int i;
char *src = bufp->page + (int)OFFSET(bp);
char *dst = src + (int)pairlen;
memmove(dst, src, (size_t)(bp[ndx + 1] - OFFSET(bp)));
/* Now adjust the pointers */
for (i = ndx + 2; i <= n; i += 2) {
if (bp[i + 1] == OVFLPAGE) {
bp[i - 2] = bp[i];
bp[i - 1] = bp[i + 1];
} else {
bp[i - 2] = bp[i] + pairlen;
bp[i - 1] = bp[i + 1] + pairlen;
}
}
}
/* Finally adjust the page data */
bp[n] = OFFSET(bp) + pairlen;
temp = bp[n + 1] + pairlen + 2 * sizeof(uint16_t);
_DIAGASSERT(temp <= 0xffff);
bp[n - 1] = (uint16_t)temp;
bp[0] = n - 2;
hashp->NKEYS--;
bufp->flags |= BUF_MOD;
return (0);
}
/*
* Returns:
* 0 OK
* -1 error
*/
extern int
__delpair(HTAB *hashp, BUFHEAD *bufp, int ndx)
{
register uint16 *bp, newoff;
register int n;
uint16 pairlen;
bp = (uint16 *)bufp->page;
n = bp[0];
if (bp[ndx + 1] < REAL_KEY)
return (__big_delete(hashp, bufp));
if (ndx != 1)
newoff = bp[ndx - 1];
else
newoff = hashp->BSIZE;
pairlen = newoff - bp[ndx + 1];
if (ndx != (n - 1)) {
/* Hard Case -- need to shuffle keys */
register int i;
register char *src = bufp->page + (int)OFFSET(bp);
uint32 dst_offset = (uint32)OFFSET(bp) + (uint32)pairlen;
register char *dst = bufp->page + dst_offset;
uint32 length = bp[ndx + 1] - OFFSET(bp);
/*
* +-----------+XXX+---------+XXX+---------+---------> +infinity
* | | | |
* 0 src_offset dst_offset BSIZE
*
* Dst_offset is > src_offset, so if src_offset were bad, dst_offset
* would be too, therefore we check only dst_offset.
*
* If dst_offset is >= BSIZE, either OFFSET(bp), or pairlen, or both
* is corrupted.
*
* Once we know dst_offset is < BSIZE, we can subtract it from BSIZE
* to get an upper bound on length.
*/
if (dst_offset > (uint32)hashp->BSIZE)
return (DATABASE_CORRUPTED_ERROR);
if (length > (uint32)(hashp->BSIZE - dst_offset))
return (DATABASE_CORRUPTED_ERROR);
memmove(dst, src, length);
/* Now adjust the pointers */
for (i = ndx + 2; i <= n; i += 2) {
if (bp[i + 1] == OVFLPAGE) {
bp[i - 2] = bp[i];
bp[i - 1] = bp[i + 1];
} else {
bp[i - 2] = bp[i] + pairlen;
bp[i - 1] = bp[i + 1] + pairlen;
}
}
}
/* Finally adjust the page data */
bp[n] = OFFSET(bp) + pairlen;
bp[n - 1] = bp[n + 1] + pairlen + 2 * sizeof(uint16);
bp[0] = n - 2;
hashp->NKEYS--;
bufp->flags |= BUF_MOD;
return (0);
}
