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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1996, 1997, 1998
* Sleepycat Software. All rights reserved.
*/
/*
* Copyright (c) 1990, 1993, 1994, 1995, 1996
* Keith Bostic. All rights reserved.
*/
/*
* Copyright (c) 1990, 1993, 1994, 1995
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Mike Olson.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "config.h"
#ifndef lint
static const char sccsid[] = "@(#)bt_compare.c 10.9 (Sleepycat) 5/6/98";
#endif /* not lint */
#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#include <string.h>
#endif
#include "db_int.h"
#include "db_page.h"
#include "btree.h"
/*
* __bam_cmp --
* Compare a key to a given record.
*
* PUBLIC: int __bam_cmp __P((DB *, const DBT *, EPG *));
*/
int
__bam_cmp(dbp, k1, e)
DB *dbp;
const DBT *k1;
EPG *e;
{
BINTERNAL *bi;
BKEYDATA *bk;
BOVERFLOW *bo;
BTREE *t;
DBT k2;
PAGE *h;
t = dbp->internal;
/*
* Returns:
* < 0 if k1 is < record
* = 0 if k1 is = record
* > 0 if k1 is > record
*
* The left-most key on internal pages, at any level of the tree, is
* guaranteed, by the following code, to be less than any user key.
* This saves us from having to update the leftmost key on an internal
* page when the user inserts a new key in the tree smaller than
* anything we've yet seen.
*/
h = e->page;
if (e->indx == 0 &&
h->prev_pgno == PGNO_INVALID && TYPE(h) != P_LBTREE)
return (1);
bo = NULL;
if (TYPE(h) == P_LBTREE) {
bk = GET_BKEYDATA(h, e->indx);
if (B_TYPE(bk->type) == B_OVERFLOW)
bo = (BOVERFLOW *)bk;
else {
k2.data = bk->data;
k2.size = bk->len;
}
} else {
bi = GET_BINTERNAL(h, e->indx);
if (B_TYPE(bi->type) == B_OVERFLOW)
bo = (BOVERFLOW *)(bi->data);
else {
k2.data = bi->data;
k2.size = bi->len;
}
}
/*
* XXX
* We ignore system errors; the only recoverable one is ENOMEM, and we
* don't want to require that comparison routines handle random errors.
* We don't want to return a valid comparison, either, so we stop.
*/
if (bo != NULL) {
/*
* If using the default comparison routine, use __db_moff(),
* which compares the overflow key a page at a time.
*/
if (t->bt_compare == __bam_defcmp)
return (__db_moff(dbp, k1, bo->pgno));
/*
* Otherwise, we need a contiguous record so we can hand it
* to the user's routine.
*/
memset(&k2, 0, sizeof(k2));
if (__db_goff(dbp, &k2, bo->tlen,
bo->pgno, &t->bt_rdata.data, &t->bt_rdata.ulen) != 0) {
(void)__db_panic(dbp);
return (0);
}
}
/*
* XXX
* Note, we have not cleared the k2 DBT in this path. This should
* be okay, because the user's comparison routine had better not be
* looking at any fields other than the data/size. We don't clear
* it because we go through this path a lot and it's expensive.
*/
return ((*t->bt_compare)(k1, &k2));
}
/*
* __bam_defcmp --
* Default comparison routine.
*
* PUBLIC: int __bam_defcmp __P((const DBT *, const DBT *));
*/
int
__bam_defcmp(a, b)
const DBT *a, *b;
{
size_t len;
u_int8_t *p1, *p2;
/*
* Returns:
* < 0 if a is < b
* = 0 if a is = b
* > 0 if a is > b
*
* XXX
* If a size_t doesn't fit into a long, or if the difference between
* any two characters doesn't fit into an int, this routine can lose.
* What we need is a signed integral type that's guaranteed to be at
* least as large as a size_t, and there is no such thing.
*/
len = a->size > b->size ? b->size : a->size;
for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
if (*p1 != *p2)
return ((long)*p1 - (long)*p2);
return ((long)a->size - (long)b->size);
}
/*
* __bam_defpfx --
* Default prefix routine.
*
* PUBLIC: size_t __bam_defpfx __P((const DBT *, const DBT *));
*/
size_t
__bam_defpfx(a, b)
const DBT *a, *b;
{
size_t cnt, len;
u_int8_t *p1, *p2;
cnt = 1;
len = a->size > b->size ? b->size : a->size;
for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
if (*p1 != *p2)
return (cnt);
/*
* We know that a->size must be <= b->size, or they wouldn't be
* in this order.
*/
return (a->size < b->size ? a->size + 1 : a->size);
}
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