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	memmem.c - sbase - suckless unix tools
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	memmem.c (2328B)
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	1 /* $OpenBSD: memmem.c,v 1.4 2015/08/31 02:53:57 guenther Exp $ */
	2
	3 /*
	4 * Copyright (c) 2005 Pascal Gloor <[email protected]>
	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 distributio…
	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 PU…
	21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIAB…
	22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUE…
	23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOO…
	24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, S…
	26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY…
	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 }