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/* $OpenBSD: memmem.c,v 1.4 2015/08/31 02:53:57 guenther Exp $ */ |
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/*- |
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* Copyright (c) 2005 Pascal Gloor <pascal.gloor@spale.com> |
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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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* 3. The name of the author may not be used to endorse or promote |
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* products derived from this software without specific prior written |
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* permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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*/ |
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#include <string.h> |
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/* |
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* Find the first occurrence of the byte string s in byte string l. |
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*/ |
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void * |
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memmem(const void *l, size_t l_len, const void *s, size_t s_len) |
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{ |
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const char *cur, *last; |
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const char *cl = l; |
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const char *cs = s; |
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/* a zero length needle should just return the haystack */ |
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if (s_len == 0) |
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return (void *)cl; |
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/* "s" must be smaller or equal to "l" */ |
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if (l_len < s_len) |
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return NULL; |
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/* special case where s_len == 1 */ |
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if (s_len == 1) |
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return memchr(l, *cs, l_len); |
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/* the last position where its possible to find "s" in "l" */ |
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last = cl + l_len - s_len; |
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for (cur = cl; cur <= last; cur++) |
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if (cur[0] == cs[0] && memcmp(cur, cs, s_len) == 0) |
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return (void *)cur; |
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return NULL; |
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} |
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DEF_WEAK(memmem); |