261 lines
6.7 KiB
C
261 lines
6.7 KiB
C
/*-
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* Copyright (c) 1990, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Mike Olson.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)bt_utils.c 8.8 (Berkeley) 7/20/94";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/param.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <db.h>
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#include "btree.h"
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/*
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* __bt_ret --
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* Build return key/data pair.
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*
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* Parameters:
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* t: tree
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* e: key/data pair to be returned
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* key: user's key structure (NULL if not to be filled in)
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* rkey: memory area to hold key
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* data: user's data structure (NULL if not to be filled in)
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* rdata: memory area to hold data
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* copy: always copy the key/data item
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*
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* Returns:
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* RET_SUCCESS, RET_ERROR.
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*/
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int
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__bt_ret(t, e, key, rkey, data, rdata, copy)
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BTREE *t;
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EPG *e;
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DBT *key, *rkey, *data, *rdata;
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int copy;
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{
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BLEAF *bl;
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void *p;
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bl = GETBLEAF(e->page, e->index);
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/*
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* We must copy big keys/data to make them contigous. Otherwise,
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* leave the page pinned and don't copy unless the user specified
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* concurrent access.
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*/
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if (key == NULL)
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goto dataonly;
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if (bl->flags & P_BIGKEY) {
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if (__ovfl_get(t, bl->bytes,
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&key->size, &rkey->data, &rkey->size))
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return (RET_ERROR);
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key->data = rkey->data;
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} else if (copy || F_ISSET(t, B_DB_LOCK)) {
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if (bl->ksize > rkey->size) {
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p = (void *)(rkey->data == NULL ?
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malloc(bl->ksize) : realloc(rkey->data, bl->ksize));
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if (p == NULL)
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return (RET_ERROR);
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rkey->data = p;
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rkey->size = bl->ksize;
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}
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memmove(rkey->data, bl->bytes, bl->ksize);
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key->size = bl->ksize;
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key->data = rkey->data;
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} else {
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key->size = bl->ksize;
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key->data = bl->bytes;
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}
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dataonly:
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if (data == NULL)
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return (RET_SUCCESS);
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if (bl->flags & P_BIGDATA) {
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if (__ovfl_get(t, bl->bytes + bl->ksize,
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&data->size, &rdata->data, &rdata->size))
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return (RET_ERROR);
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data->data = rdata->data;
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} else if (copy || F_ISSET(t, B_DB_LOCK)) {
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/* Use +1 in case the first record retrieved is 0 length. */
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if (bl->dsize + 1 > rdata->size) {
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p = (void *)(rdata->data == NULL ?
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malloc(bl->dsize + 1) :
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realloc(rdata->data, bl->dsize + 1));
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if (p == NULL)
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return (RET_ERROR);
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rdata->data = p;
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rdata->size = bl->dsize + 1;
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}
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memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize);
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data->size = bl->dsize;
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data->data = rdata->data;
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} else {
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data->size = bl->dsize;
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data->data = bl->bytes + bl->ksize;
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}
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return (RET_SUCCESS);
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}
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/*
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* __BT_CMP -- Compare a key to a given record.
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*
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* Parameters:
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* t: tree
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* k1: DBT pointer of first arg to comparison
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* e: pointer to EPG for comparison
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*
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* Returns:
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* < 0 if k1 is < record
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* = 0 if k1 is = record
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* > 0 if k1 is > record
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*/
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int
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__bt_cmp(t, k1, e)
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BTREE *t;
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const DBT *k1;
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EPG *e;
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{
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BINTERNAL *bi;
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BLEAF *bl;
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DBT k2;
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PAGE *h;
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void *bigkey;
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/*
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* The left-most key on internal pages, at any level of the tree, is
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* guaranteed by the following code to be less than any user key.
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* This saves us from having to update the leftmost key on an internal
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* page when the user inserts a new key in the tree smaller than
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* anything we've yet seen.
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*/
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h = e->page;
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if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
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return (1);
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bigkey = NULL;
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if (h->flags & P_BLEAF) {
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bl = GETBLEAF(h, e->index);
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if (bl->flags & P_BIGKEY)
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bigkey = bl->bytes;
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else {
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k2.data = bl->bytes;
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k2.size = bl->ksize;
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}
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} else {
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bi = GETBINTERNAL(h, e->index);
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if (bi->flags & P_BIGKEY)
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bigkey = bi->bytes;
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else {
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k2.data = bi->bytes;
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k2.size = bi->ksize;
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}
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}
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if (bigkey) {
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if (__ovfl_get(t, bigkey,
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&k2.size, &t->bt_rdata.data, &t->bt_rdata.size))
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return (RET_ERROR);
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k2.data = t->bt_rdata.data;
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}
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return ((*t->bt_cmp)(k1, &k2));
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}
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/*
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* __BT_DEFCMP -- Default comparison routine.
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*
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* Parameters:
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* a: DBT #1
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* b: DBT #2
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*
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* Returns:
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* < 0 if a is < b
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* = 0 if a is = b
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* > 0 if a is > b
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*/
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int
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__bt_defcmp(a, b)
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const DBT *a, *b;
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{
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register size_t len;
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register u_char *p1, *p2;
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/*
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* XXX
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* If a size_t doesn't fit in an int, this routine can lose.
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* What we need is a integral type which is guaranteed to be
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* larger than a size_t, and there is no such thing.
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*/
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len = MIN(a->size, b->size);
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for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
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if (*p1 != *p2)
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return ((int)*p1 - (int)*p2);
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return ((int)a->size - (int)b->size);
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}
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/*
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* __BT_DEFPFX -- Default prefix routine.
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*
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* Parameters:
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* a: DBT #1
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* b: DBT #2
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*
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* Returns:
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* Number of bytes needed to distinguish b from a.
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*/
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size_t
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__bt_defpfx(a, b)
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const DBT *a, *b;
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{
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register u_char *p1, *p2;
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register size_t cnt, len;
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cnt = 1;
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len = MIN(a->size, b->size);
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for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
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if (*p1 != *p2)
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return (cnt);
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/* a->size must be <= b->size, or they wouldn't be in this order. */
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return (a->size < b->size ? a->size + 1 : a->size);
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}
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