xref: /openbsd-src/lib/libc/stdlib/lsearch.c (revision a28daedfc357b214be5c701aa8ba8adb29a7f1c2)
1 /*	$OpenBSD: lsearch.c,v 1.3 2004/10/01 04:08:45 jsg Exp $	*/
2 
3 /*
4  * Copyright (c) 1989, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * Roger L. Snyder.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)lsearch.c	8.1 (Berkeley) 6/4/93";
37 #endif /* LIBC_SCCS and not lint */
38 
39 #include <sys/types.h>
40 #include <string.h>
41 #include <search.h>
42 
43 typedef int (*cmp_fn_t)(const void *, const void *);
44 static void *linear_base(const void *, const void *, size_t *, size_t,
45     cmp_fn_t, int);
46 
47 void *
48 lsearch(const void *key, const void *base, size_t *nelp, size_t width,
49     	cmp_fn_t compar)
50 {
51 
52 	return(linear_base(key, base, nelp, width, compar, 1));
53 }
54 
55 void *
56 lfind(const void *key, const void *base, size_t *nelp, size_t width,
57 	cmp_fn_t compar)
58 {
59 	return(linear_base(key, base, nelp, width, compar, 0));
60 }
61 
62 static void *
63 linear_base(const void *key, const void *base, size_t *nelp, size_t width,
64 	cmp_fn_t compar, int add_flag)
65 {
66 	const char *element, *end;
67 
68 	end = (const char *)base + *nelp * width;
69 	for (element = base; element < end; element += width)
70 		if (!compar(key, element))		/* key found */
71 			return((void *)element);
72 
73 	if (!add_flag)					/* key not found */
74 		return(NULL);
75 
76 	/*
77 	 * The UNIX System User's Manual, 1986 edition claims that
78 	 * a NULL pointer is returned by lsearch with errno set
79 	 * appropriately, if there is not enough room in the table
80 	 * to add a new item.  This can't be done as none of these
81 	 * routines have any method of determining the size of the
82 	 * table.  This comment isn't in the 1986-87 System V
83 	 * manual.
84 	 */
85 	++*nelp;
86 	memcpy((void *)end, key, width);
87 	return((void *)end);
88 }
89