1 /* $NetBSD: memmem.c,v 1.2 2008/04/28 20:23:00 martin Exp $ */ 2 3 /*- 4 * Copyright (c) 2005 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Perry E. Metzger of Metzger, Dowdeswell & Co. LLC. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #if defined(LIBC_SCCS) && !defined(lint) 34 __RCSID("$NetBSD: memmem.c,v 1.2 2008/04/28 20:23:00 martin Exp $"); 35 #endif /* LIBC_SCCS and not lint */ 36 37 #if !defined(_KERNEL) && !defined(_STANDALONE) 38 #include <assert.h> 39 #include <string.h> 40 #else 41 #include <lib/libkern/libkern.h> 42 #define _DIAGASSERT(x) (void)0 43 #define NULL ((void *)0) 44 #endif 45 46 void * 47 memmem(const void *block, size_t blen, const void *pat, size_t plen) 48 { 49 const unsigned char *bp, *pp, *endp; 50 51 _DIAGASSERT(block != NULL); 52 _DIAGASSERT(pat != NULL); 53 54 /* 55 * Following the precedent in ststr(3) and glibc, a zero 56 * length pattern matches the start of block. 57 */ 58 if (plen == 0) 59 return __UNCONST(block); 60 61 if (blen < plen) 62 return NULL; 63 64 bp = block; 65 pp = pat; 66 endp = bp + (blen - plen) + 1; 67 68 /* 69 * As a cheezy optimization, check that the first chars are 70 * the same before calling memcmp. Really we should use bm(3) 71 * to speed this up if blen is large enough. 72 */ 73 while (bp < endp) { 74 if ((*bp == *pp) && (memcmp(bp, pp, plen) == 0)) 75 return __UNCONST(bp); 76 bp++; 77 } 78 79 return NULL; 80 } 81