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/* $OpenBSD: bt_utils.c,v 1.13 2022/12/27 17:10:06 jmc Exp $ */
/*-
* Copyright (c) 1990, 1993, 1994
* 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.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <db.h>
#include "btree.h"
#define MINIMUM(a, b) (((a) < (b)) ? (a) : (b))
/*
* __bt_ret --
* Build return key/data pair.
*
* Parameters:
* t: tree
* e: key/data pair to be returned
* key: user's key structure (NULL if not to be filled in)
* rkey: memory area to hold key
* data: user's data structure (NULL if not to be filled in)
* rdata: memory area to hold data
* copy: always copy the key/data item
*
* Returns:
* RET_SUCCESS, RET_ERROR.
*/
int
__bt_ret(BTREE *t, EPG *e, DBT *key, DBT *rkey, DBT *data, DBT *rdata, int copy)
{
BLEAF *bl;
void *p;
bl = GETBLEAF(e->page, e->index);
/*
* We must copy big keys/data to make them contiguous. Otherwise,
* leave the page pinned and don't copy unless the user specified
* concurrent access.
*/
if (key == NULL)
goto dataonly;
if (bl->flags & P_BIGKEY) {
if (__ovfl_get(t, bl->bytes,
&key->size, &rkey->data, &rkey->size))
return (RET_ERROR);
key->data = rkey->data;
} else if (copy || F_ISSET(t, B_DB_LOCK)) {
if (bl->ksize > rkey->size) {
p = realloc(rkey->data, bl->ksize);
if (p == NULL)
return (RET_ERROR);
rkey->data = p;
rkey->size = bl->ksize;
}
memmove(rkey->data, bl->bytes, bl->ksize);
key->size = bl->ksize;
key->data = rkey->data;
} else {
key->size = bl->ksize;
key->data = bl->bytes;
}
dataonly:
if (data == NULL)
return (RET_SUCCESS);
if (bl->flags & P_BIGDATA) {
if (__ovfl_get(t, bl->bytes + bl->ksize,
&data->size, &rdata->data, &rdata->size))
return (RET_ERROR);
data->data = rdata->data;
} else if (copy || F_ISSET(t, B_DB_LOCK)) {
/* Use +1 in case the first record retrieved is 0 length. */
if (bl->dsize + 1 > rdata->size) {
p = realloc(rdata->data, bl->dsize + 1);
if (p == NULL)
return (RET_ERROR);
rdata->data = p;
rdata->size = bl->dsize + 1;
}
memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize);
data->size = bl->dsize;
data->data = rdata->data;
} else {
data->size = bl->dsize;
data->data = bl->bytes + bl->ksize;
}
return (RET_SUCCESS);
}
/*
* __BT_CMP -- Compare a key to a given record.
*
* Parameters:
* t: tree
* k1: DBT pointer of first arg to comparison
* e: pointer to EPG for comparison
*
* Returns:
* < 0 if k1 is < record
* = 0 if k1 is = record
* > 0 if k1 is > record
*/
int
__bt_cmp(BTREE *t, const DBT *k1, EPG *e)
{
BINTERNAL *bi;
BLEAF *bl;
DBT k2;
PAGE *h;
void *bigkey;
/*
* 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->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
return (1);
bigkey = NULL;
if (h->flags & P_BLEAF) {
bl = GETBLEAF(h, e->index);
if (bl->flags & P_BIGKEY)
bigkey = bl->bytes;
else {
k2.data = bl->bytes;
k2.size = bl->ksize;
}
} else {
bi = GETBINTERNAL(h, e->index);
if (bi->flags & P_BIGKEY)
bigkey = bi->bytes;
else {
k2.data = bi->bytes;
k2.size = bi->ksize;
}
}
if (bigkey) {
if (__ovfl_get(t, bigkey,
&k2.size, &t->bt_rdata.data, &t->bt_rdata.size))
return (RET_ERROR);
k2.data = t->bt_rdata.data;
}
return ((*t->bt_cmp)(k1, &k2));
}
/*
* __BT_DEFCMP -- Default comparison routine.
*
* Parameters:
* a: DBT #1
* b: DBT #2
*
* Returns:
* < 0 if a is < b
* = 0 if a is = b
* > 0 if a is > b
*/
int
__bt_defcmp(const DBT *a, const DBT *b)
{
size_t len;
u_char *p1, *p2;
/*
* XXX
* If a size_t doesn't fit in an int, this routine can lose.
* What we need is a integral type which is guaranteed to be
* larger than a size_t, and there is no such thing.
*/
len = MINIMUM(a->size, b->size);
for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
if (*p1 != *p2)
return ((int)*p1 - (int)*p2);
return ((int)a->size - (int)b->size);
}
/*
* __BT_DEFPFX -- Default prefix routine.
*
* Parameters:
* a: DBT #1
* b: DBT #2
*
* Returns:
* Number of bytes needed to distinguish b from a.
*/
size_t
__bt_defpfx(const DBT *a, const DBT *b)
{
u_char *p1, *p2;
size_t cnt, len;
cnt = 1;
len = MINIMUM(a->size, b->size);
for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
if (*p1 != *p2)
return (cnt);
/* 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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