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