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#include <sys/libkern.h>
31#include <sys/param.h>
32
33void *
34memmem(const void *l, size_t l_len, const void *s, size_t s_len)
35{
36        char *cur, *last;
37        const char *cl = (const char *)l;
38        const char *cs = (const char *)s;
39
40        /* we need something to compare */
41        if (l_len == 0 || s_len == 0)
42                return NULL;
43
44        /* "s" must be smaller or equal to "l" */
45        if (l_len < s_len)
46                return NULL;
47
48        /* special case where s_len == 1 */
49        if (s_len == 1)
50                return memchr(l, (int)*cs, l_len);
51
52        /* the last position where its possible to find "s" in "l" */
53        last = __DECONST(char *, cl) + l_len - s_len;
54
55        for (cur = __DECONST(char *, cl); cur <= last; cur++)
56                if (cur[0] == cs[0] && memcmp(cur, cs, s_len) == 0)
57                        return cur;
58
59        return NULL;
60}
61