16150352f5
This function originated in glibc, and this matches their behaviour (and NetBSD, OpenBSD, and musl). An empty big string (arg "l") is handled by the existing l_len < s_len test. Reviewed by: bapt, ngie Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D2657
66 lines
2.3 KiB
C
66 lines
2.3 KiB
C
/*-
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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 <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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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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register char *cur, *last;
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const char *cl = (const char *)l;
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const char *cs = (const char *)s;
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/* empty "s" matches the beginning of "l" */
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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, (int)*cs, l_len);
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/* the last position where its possible to find "s" in "l" */
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last = (char *)cl + l_len - s_len;
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for (cur = (char *)cl; cur <= last; cur++)
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if (cur[0] == cs[0] && memcmp(cur, cs, s_len) == 0)
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return cur;
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return NULL;
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}
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