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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1996-2004
* 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. 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.
*
* $Id: bt_compare.c,v 11.20 2004/02/21 15:54:44 bostic Exp $
*/
#include "db_config.h"
#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#endif
#include "db_int.h"
#include "dbinc/db_page.h"
#include "dbinc/btree.h"
/*
* __bam_cmp --
* Compare a key to a given record.
*
* PUBLIC: int __bam_cmp __P((DB *, const DBT *, PAGE *,
* PUBLIC: u_int32_t, int (*)(DB *, const DBT *, const DBT *), int *));
*/
int
__bam_cmp(dbp, dbt, h, indx, func, cmpp)
DB *dbp;
const DBT *dbt;
PAGE *h;
u_int32_t indx;
int (*func)__P((DB *, const DBT *, const DBT *));
int *cmpp;
{
BINTERNAL *bi;
BKEYDATA *bk;
BOVERFLOW *bo;
DBT pg_dbt;
/*
* Returns:
* < 0 if dbt is < page record
* = 0 if dbt is = page record
* > 0 if dbt is > page record
*
* !!!
* We do not clear the pg_dbt DBT even though it's likely to contain
* random bits. That should be okay, because the app's comparison
* routine had better not be looking at fields other than data/size.
* We don't clear it because we go through this path a lot and it's
* expensive.
*/
switch (TYPE(h)) {
case P_LBTREE:
case P_LDUP:
case P_LRECNO:
bk = GET_BKEYDATA(dbp, h, indx);
if (B_TYPE(bk->type) == B_OVERFLOW)
bo = (BOVERFLOW *)bk;
else {
pg_dbt.data = bk->data;
pg_dbt.size = bk->len;
*cmpp = func(dbp, dbt, &pg_dbt);
return (0);
}
break;
case P_IBTREE:
/*
* The following code guarantees that the left-most key on an
* internal page at any place in the tree sorts less than any
* user-specified key. The reason is that if we have reached
* this internal page, we know the user key must sort greater
* than the key we're storing for this page in any internal
* pages at levels above us in the tree. It then follows that
* any user-specified key cannot sort less than the first page
* which we reference, and so there's no reason to call the
* comparison routine. While this may save us a comparison
* routine call or two, the real reason for this is because
* we don't maintain a copy of the smallest key in the tree,
* so that we don't have to update all the levels of the tree
* should the application store a new smallest key. And, so,
* we may not have a key to compare, which makes doing the
* comparison difficult and error prone.
*/
if (indx == 0) {
*cmpp = 1;
return (0);
}
bi = GET_BINTERNAL(dbp, h, indx);
if (B_TYPE(bi->type) == B_OVERFLOW)
bo = (BOVERFLOW *)(bi->data);
else {
pg_dbt.data = bi->data;
pg_dbt.size = bi->len;
*cmpp = func(dbp, dbt, &pg_dbt);
return (0);
}
break;
default:
return (__db_pgfmt(dbp->dbenv, PGNO(h)));
}
/*
* Overflow.
*/
return (__db_moff(dbp, dbt,
bo->pgno, bo->tlen, func == __bam_defcmp ? NULL : func, cmpp));
}
/*
* __bam_defcmp --
* Default comparison routine.
*
* PUBLIC: int __bam_defcmp __P((DB *, const DBT *, const DBT *));
*/
int
__bam_defcmp(dbp, a, b)
DB *dbp;
const DBT *a, *b;
{
size_t len;
u_int8_t *p1, *p2;
COMPQUIET(dbp, NULL);
/*
* 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((DB *, const DBT *, const DBT *));
*/
size_t
__bam_defpfx(dbp, a, b)
DB *dbp;
const DBT *a, *b;
{
size_t cnt, len;
u_int8_t *p1, *p2;
COMPQUIET(dbp, NULL);
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);
/*
* They match up to the smaller of the two sizes.
* Collate the longer after the shorter.
*/
if (a->size < b->size)
return (a->size + 1);
if (b->size < a->size)
return (b->size + 1);
return (b->size);
}
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