GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libc/db/btree/bt_search.c Lines: 0 53 0.0 %
Date: 2017-11-13 Branches: 0 34 0.0 %

Line Branch Exec Source
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/*	$OpenBSD: bt_search.c,v 1.10 2005/08/05 13:02:59 espie 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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#include <sys/types.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 + (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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}