This patch imports the unmodified current version of NetBSD libc. The NetBSD includes are in /nbsd_include, while the libc code itself is split between lib/nbsd_libc and common/lib/libc.
205 lines
5.6 KiB
C
205 lines
5.6 KiB
C
/* $NetBSD: bt_search.c,v 1.17 2008/09/11 12:58:00 joerg Exp $ */
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/*-
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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. 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 HAVE_NBTOOL_CONFIG_H
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#include "nbtool_config.h"
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#endif
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#include <sys/cdefs.h>
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__RCSID("$NetBSD: bt_search.c,v 1.17 2008/09/11 12:58:00 joerg Exp $");
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#include "namespace.h"
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#include <sys/types.h>
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#include <assert.h>
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#include <stdio.h>
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#include <db.h>
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#include "btree.h"
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static int __bt_snext(BTREE *, PAGE *, const DBT *, int *);
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static int __bt_sprev(BTREE *, PAGE *, const DBT *, int *);
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/*
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* __bt_search --
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* Search a btree for a key.
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*
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* Parameters:
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* t: tree to search
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* key: key to find
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* exactp: pointer to exact match flag
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*
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* Returns:
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* The EPG for matching record, if any, or the EPG for the location
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* of the key, if it were inserted into the tree, is entered into
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* the bt_cur field of the tree. A pointer to the field is returned.
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*/
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EPG *
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__bt_search(BTREE *t, const DBT *key, int *exactp)
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{
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PAGE *h;
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indx_t base, idx, lim;
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pgno_t pg;
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int cmp;
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BT_CLR(t);
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for (pg = P_ROOT;;) {
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if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
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return (NULL);
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/* Do a binary search on the current page. */
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t->bt_cur.page = h;
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for (base = 0, lim = NEXTINDEX(h); lim; lim >>= 1) {
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t->bt_cur.index = idx = base + ((uint32_t)lim >> 1);
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if ((cmp = __bt_cmp(t, key, &t->bt_cur)) == 0) {
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if (h->flags & P_BLEAF) {
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*exactp = 1;
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return (&t->bt_cur);
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}
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goto next;
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}
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if (cmp > 0) {
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base = idx + 1;
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--lim;
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}
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}
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/*
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* If it's a leaf page, we're almost done. If no duplicates
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* are allowed, or we have an exact match, we're done. Else,
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* it's possible that there were matching keys on this page,
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* which later deleted, and we're on a page with no matches
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* while there are matches on other pages. If at the start or
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* end of a page, check the adjacent page.
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*/
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if (h->flags & P_BLEAF) {
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if (!F_ISSET(t, B_NODUPS)) {
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if (base == 0 &&
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h->prevpg != P_INVALID &&
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__bt_sprev(t, h, key, exactp))
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return (&t->bt_cur);
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if (base == NEXTINDEX(h) &&
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h->nextpg != P_INVALID &&
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__bt_snext(t, h, key, exactp))
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return (&t->bt_cur);
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}
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*exactp = 0;
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t->bt_cur.index = base;
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return (&t->bt_cur);
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}
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/*
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* No match found. Base is the smallest index greater than
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* key and may be zero or a last + 1 index. If it's non-zero,
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* decrement by one, and record the internal page which should
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* be a parent page for the key. If a split later occurs, the
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* inserted page will be to the right of the saved page.
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*/
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idx = base ? base - 1 : base;
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next: BT_PUSH(t, h->pgno, idx);
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pg = GETBINTERNAL(h, idx)->pgno;
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mpool_put(t->bt_mp, h, 0);
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}
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}
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/*
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* __bt_snext --
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* Check for an exact match after the key.
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*
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* Parameters:
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* t: tree
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* h: current page
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* key: key
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* exactp: pointer to exact match flag
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*
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* Returns:
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* If an exact match found.
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*/
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static int
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__bt_snext(BTREE *t, PAGE *h, const DBT *key, int *exactp)
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{
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EPG e;
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/*
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* Get the next page. The key is either an exact
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* match, or not as good as the one we already have.
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*/
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if ((e.page = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
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return (0);
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e.index = 0;
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if (__bt_cmp(t, key, &e) == 0) {
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mpool_put(t->bt_mp, h, 0);
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t->bt_cur = e;
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*exactp = 1;
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return (1);
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}
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mpool_put(t->bt_mp, e.page, 0);
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return (0);
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}
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/*
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* __bt_sprev --
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* Check for an exact match before the key.
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*
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* Parameters:
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* t: tree
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* h: current page
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* key: key
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* exactp: pointer to exact match flag
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*
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* Returns:
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* If an exact match found.
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*/
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static int
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__bt_sprev(BTREE *t, PAGE *h, const DBT *key, int *exactp)
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{
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EPG e;
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/*
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* Get the previous page. The key is either an exact
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* match, or not as good as the one we already have.
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*/
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if ((e.page = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
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return (0);
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e.index = NEXTINDEX(e.page) - 1;
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if (__bt_cmp(t, key, &e) == 0) {
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mpool_put(t->bt_mp, h, 0);
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t->bt_cur = e;
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*exactp = 1;
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return (1);
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}
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mpool_put(t->bt_mp, e.page, 0);
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return (0);
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}
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