1 /* $OpenBSD: memmem.c,v 1.4 2015/08/31 02:53:57 guenther Exp $ */ 2 /*- 3 * Copyright (c) 2005 Pascal Gloor <pascal.gloor@spale.com> 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. The name of the author may not be used to endorse or promote 14 * products derived from this software without specific prior written 15 * permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #define _DEFAULT_SOURCE 31 #include <string.h> 32 33 /* 34 * Find the first occurrence of the byte string s in byte string l. 35 */ 36 37 void * 38 memmem(const void *l, size_t l_len, const void *s, size_t s_len) 39 { 40 const char *cur, *last; 41 const char *cl = l; 42 const char *cs = s; 43 44 /* a zero length needle should just return the haystack */ 45 if (s_len == 0) 46 return (void *)cl; 47 48 /* "s" must be smaller or equal to "l" */ 49 if (l_len < s_len) 50 return NULL; 51 52 /* special case where s_len == 1 */ 53 if (s_len == 1) 54 return memchr(l, *cs, l_len); 55 56 /* the last position where its possible to find "s" in "l" */ 57 last = cl + l_len - s_len; 58 59 for (cur = cl; cur <= last; cur++) 60 if (cur[0] == cs[0] && memcmp(cur, cs, s_len) == 0) 61 return (void *)cur; 62 63 return NULL; 64 } 65