xref: /minix3/lib/libc/stdlib/lsearch.c (revision f14fb602092e015ff630df58e17c2a9cd57d29b3)
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
36 static 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 
49 typedef int (*cmp_fn_t)(const void *, const void *);
50 static void *linear_base(const void *, void *, size_t *, size_t,
51 			     cmp_fn_t, int);
52 
53 void *
lsearch(const void * key,void * base,size_t * nelp,size_t width,cmp_fn_t compar)54 lsearch(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 
65 void *
lfind(const void * key,const void * base,size_t * nelp,size_t width,cmp_fn_t compar)66 lfind(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 
77 static void *
linear_base(const void * key,void * base,size_t * nelp,size_t width,cmp_fn_t compar,int add_flag)78 linear_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