xref: /titanic_41/usr/src/lib/libc/port/gen/memmem.c (revision dab7de2d0395d3b5e8dc742f164561b3840dd8c6)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
24  */
25 
26 /*
27  * Copyright (c) 2005 Pascal Gloor <pascal.gloor@spale.com>
28  *
29  * Redistribution and use in source and binary forms, with or without
30  * modification, are permitted provided that the following conditions
31  * are met:
32  * 1. Redistributions of source code must retain the above copyright
33  *    notice, this list of conditions and the following disclaimer.
34  * 2. Redistributions in binary form must reproduce the above copyright
35  *    notice, this list of conditions and the following disclaimer in the
36  *    documentation and/or other materials provided with the distribution.
37  * 3. The name of the author may not be used to endorse or promote
38  *    products derived from this software without specific prior written
39  *    permission.
40  *
41  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
51  * SUCH DAMAGE.
52  */
53 
54 #include <string.h>
55 
56 /*
57  * Find the first occurrence of the byte string s in byte string l.
58  */
59 
60 void *
61 memmem(const void *l, size_t l_len, const void *s, size_t s_len)
62 {
63 	char *cur, *last;
64 	const char *cl = (const char *)l;
65 	const char *cs = (const char *)s;
66 
67 	/* we need something to compare */
68 	if (l_len == 0 || s_len == 0)
69 		return (NULL);
70 
71 	/* "s" must be smaller or equal to "l" */
72 	if (l_len < s_len)
73 		return (NULL);
74 
75 	/* special case where s_len == 1 */
76 	if (s_len == 1)
77 		return (memchr(l, (int)*cs, l_len));
78 
79 	/* the last position where its possible to find "s" in "l" */
80 	last = (char *)cl + l_len - s_len;
81 
82 	for (cur = (char *)cl; cur <= last; cur++)
83 		if (cur[0] == cs[0] && memcmp(cur, cs, s_len) == 0)
84 			return (cur);
85 
86 	return (NULL);
87 }
88