memmem.c (2328B)
1 /* $OpenBSD: memmem.c,v 1.4 2015/08/31 02:53:57 guenther Exp $ */ 2 3 /* 4 * Copyright (c) 2005 Pascal Gloor <pascal.gloor@spale.com> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The name of the author may not be used to endorse or promote 15 * products derived from this software without specific prior written 16 * permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <string.h> 32 33 #include "../util.h" 34 35 /* 36 * Find the first occurrence of the byte string s in byte string l. 37 */ 38 39 void * 40 memmem(const void *l, size_t l_len, const void *s, size_t s_len) 41 { 42 const char *cur, *last; 43 const char *cl = l; 44 const char *cs = s; 45 46 /* a zero length needle should just return the haystack */ 47 if (s_len == 0) 48 return (void *)cl; 49 50 /* "s" must be smaller or equal to "l" */ 51 if (l_len < s_len) 52 return NULL; 53 54 /* special case where s_len == 1 */ 55 if (s_len == 1) 56 return memchr(l, *cs, l_len); 57 58 /* the last position where its possible to find "s" in "l" */ 59 last = cl + l_len - s_len; 60 61 for (cur = cl; cur <= last; cur++) 62 if (cur[0] == cs[0] && memcmp(cur, cs, s_len) == 0) 63 return (void *)cur; 64 65 return NULL; 66 }