lsearch.c revision 7f3a272ae327c647db4caeaea2a3c7af50bd73b5 
1/*
2 * Copyright (c) 1989, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Roger L. Snyder.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#include <sys/cdefs.h>
34#if defined(LIBC_SCCS) && !defined(lint)
35#if 0
36static char sccsid[] = "@(#)lsearch.c	8.1 (Berkeley) 6/4/93";
37#else
38__RCSID("$NetBSD: lsearch.c,v 1.7 2012/06/25 22:32:45 abs Exp $");
39#endif
40#endif /* LIBC_SCCS and not lint */
41
42#include <sys/types.h>
43
44#include <assert.h>
45#include <errno.h>
46#include <string.h>
47#include <search.h>
48
49typedef int (*cmp_fn_t)(const void *, const void *);
50static void *linear_base(const void *, void *, size_t *, size_t,
51			     cmp_fn_t, int);
52
53void *
54lsearch(const void *key, void *base, size_t *nelp, size_t width,
55    cmp_fn_t compar)
56{
57
58	_DIAGASSERT(key != NULL);
59	_DIAGASSERT(base != NULL);
60	_DIAGASSERT(compar != NULL);
61
62	return(linear_base(key, base, nelp, width, compar, 1));
63}
64
65void *
66lfind(const void *key, const void *base, size_t *nelp, size_t width,
67    cmp_fn_t compar)
68{
69
70	_DIAGASSERT(key != NULL);
71	_DIAGASSERT(base != NULL);
72	_DIAGASSERT(compar != NULL);
73
74	return(linear_base(key, __UNCONST(base), nelp, width, compar, 0));
75}
76
77static void *
78linear_base(const void *key, void *base, size_t *nelp, size_t width,
79	cmp_fn_t compar, int add_flag)
80{
81	char *element, *end;
82
83	_DIAGASSERT(key != NULL);
84	_DIAGASSERT(base != NULL);
85	_DIAGASSERT(compar != NULL);
86
87	end = (char *)base + *nelp * width;
88	for (element = (char *)base; element < end; element += width)
89		if (!compar(element, key))		/* key found */
90			return element;
91
92	if (!add_flag)					/* key not found */
93		return(NULL);
94
95	/*
96	 * The UNIX System User's Manual, 1986 edition claims that
97	 * a NULL pointer is returned by lsearch with errno set
98	 * appropriately, if there is not enough room in the table
99	 * to add a new item.  This can't be done as none of these
100	 * routines have any method of determining the size of the
101	 * table.  This comment isn't in the 1986-87 System V
102	 * manual.
103	 */
104	++*nelp;
105	memcpy(end, key, width);
106	return end;
107}
108