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 #include <string.h> 31 32 #include "compat.h" 33 34 /* 35 * Find the first occurrence of the byte string s in byte string l. 36 */ 37 38 void * 39 memmem(const void *l, size_t l_len, const void *s, size_t s_len) 40 { 41 const char *cur, *last; 42 const char *cl = l; 43 const char *cs = s; 44 45 /* a zero length needle should just return the haystack */ 46 if (s_len == 0) 47 return (void *)cl; 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, *cs, l_len); 56 57 /* the last position where its possible to find "s" in "l" */ 58 last = cl + l_len - s_len; 59 60 for (cur = cl; cur <= last; cur++) 61 if (cur[0] == cs[0] && memcmp(cur, cs, s_len) == 0) 62 return (void *)cur; 63 64 return NULL; 65 } 66