1/*-
2 * Copyright (c) 2005 Pascal Gloor <pascal.gloor@spale.com>
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 * 3. The name of the author may not be used to endorse or promote
13 *    products derived from this software without specific prior written
14 *    permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD: src/lib/libc/string/memmem.c,v 1.2 2009/02/03 17:58:20 danger Exp $");
31
32#include <string.h>
33
34/*
35 * Find the first occurrence of the byte string s in byte string l.
36 */
37
38void *
39memmem(const void *l, size_t l_len, const void *s, size_t s_len)
40{
41	register char *cur, *last;
42	const char *cl = (const char *)l;
43	const char *cs = (const char *)s;
44
45	/* we need something to compare */
46	if (l_len == 0 || s_len == 0)
47		return NULL;
48
49	/* "s" must be smaller or equal to "l" */
50	if (l_len < s_len)
51		return NULL;
52
53	/* special case where s_len == 1 */
54	if (s_len == 1)
55		return memchr(l, (int)*cs, l_len);
56
57	/* the last position where its possible to find "s" in "l" */
58	last = (char *)cl + l_len - s_len;
59
60	for (cur = (char *)cl; cur <= last; cur++)
61		if (cur[0] == cs[0] && memcmp(cur, cs, s_len) == 0)
62			return cur;
63
64	return NULL;
65}
66