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/* $NetBSD: memmem.c,v 1.2 2008/04/28 20:23:00 martin Exp $ */
/*-
* Copyright (c) 2005 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Perry E. Metzger of Metzger, Dowdeswell & Co. LLC.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <assert.h>
#include <string.h>
void *
memmem(const void *block, size_t blen, const void *pat, size_t plen)
{
const unsigned char *bp, *pp, *endp;
assert(block != NULL);
assert(pat != NULL);
/*
* Following the precedent in ststr(3) and glibc, a zero
* length pattern matches the start of block.
*/
if (plen == 0)
return (void*) block;
if (blen < plen)
return NULL;
bp = block;
pp = pat;
endp = bp + (blen - plen) + 1;
/*
* As a cheezy optimization, check that the first chars are
* the same before calling memcmp. Really we should use bm(3)
* to speed this up if blen is large enough.
*/
while (bp < endp) {
if ((*bp == *pp) && (memcmp(bp, pp, plen) == 0))
return (void *) bp;
bp++;
}
return NULL;
}
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