xref: /onnv-gate/usr/src/lib/libc/port/gen/memmem.c (revision 13093:48f2dbca79a2)
1*13093SRoger.Faulkner@Oracle.COM /*
2*13093SRoger.Faulkner@Oracle.COM  * CDDL HEADER START
3*13093SRoger.Faulkner@Oracle.COM  *
4*13093SRoger.Faulkner@Oracle.COM  * The contents of this file are subject to the terms of the
5*13093SRoger.Faulkner@Oracle.COM  * Common Development and Distribution License (the "License").
6*13093SRoger.Faulkner@Oracle.COM  * You may not use this file except in compliance with the License.
7*13093SRoger.Faulkner@Oracle.COM  *
8*13093SRoger.Faulkner@Oracle.COM  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9*13093SRoger.Faulkner@Oracle.COM  * or http://www.opensolaris.org/os/licensing.
10*13093SRoger.Faulkner@Oracle.COM  * See the License for the specific language governing permissions
11*13093SRoger.Faulkner@Oracle.COM  * and limitations under the License.
12*13093SRoger.Faulkner@Oracle.COM  *
13*13093SRoger.Faulkner@Oracle.COM  * When distributing Covered Code, include this CDDL HEADER in each
14*13093SRoger.Faulkner@Oracle.COM  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15*13093SRoger.Faulkner@Oracle.COM  * If applicable, add the following below this CDDL HEADER, with the
16*13093SRoger.Faulkner@Oracle.COM  * fields enclosed by brackets "[]" replaced with your own identifying
17*13093SRoger.Faulkner@Oracle.COM  * information: Portions Copyright [yyyy] [name of copyright owner]
18*13093SRoger.Faulkner@Oracle.COM  *
19*13093SRoger.Faulkner@Oracle.COM  * CDDL HEADER END
20*13093SRoger.Faulkner@Oracle.COM  */
21*13093SRoger.Faulkner@Oracle.COM 
22*13093SRoger.Faulkner@Oracle.COM /*
23*13093SRoger.Faulkner@Oracle.COM  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
24*13093SRoger.Faulkner@Oracle.COM  */
25*13093SRoger.Faulkner@Oracle.COM 
26*13093SRoger.Faulkner@Oracle.COM /*
27*13093SRoger.Faulkner@Oracle.COM  * Copyright (c) 2005 Pascal Gloor <pascal.gloor@spale.com>
28*13093SRoger.Faulkner@Oracle.COM  *
29*13093SRoger.Faulkner@Oracle.COM  * Redistribution and use in source and binary forms, with or without
30*13093SRoger.Faulkner@Oracle.COM  * modification, are permitted provided that the following conditions
31*13093SRoger.Faulkner@Oracle.COM  * are met:
32*13093SRoger.Faulkner@Oracle.COM  * 1. Redistributions of source code must retain the above copyright
33*13093SRoger.Faulkner@Oracle.COM  *    notice, this list of conditions and the following disclaimer.
34*13093SRoger.Faulkner@Oracle.COM  * 2. Redistributions in binary form must reproduce the above copyright
35*13093SRoger.Faulkner@Oracle.COM  *    notice, this list of conditions and the following disclaimer in the
36*13093SRoger.Faulkner@Oracle.COM  *    documentation and/or other materials provided with the distribution.
37*13093SRoger.Faulkner@Oracle.COM  * 3. The name of the author may not be used to endorse or promote
38*13093SRoger.Faulkner@Oracle.COM  *    products derived from this software without specific prior written
39*13093SRoger.Faulkner@Oracle.COM  *    permission.
40*13093SRoger.Faulkner@Oracle.COM  *
41*13093SRoger.Faulkner@Oracle.COM  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
42*13093SRoger.Faulkner@Oracle.COM  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43*13093SRoger.Faulkner@Oracle.COM  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44*13093SRoger.Faulkner@Oracle.COM  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45*13093SRoger.Faulkner@Oracle.COM  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46*13093SRoger.Faulkner@Oracle.COM  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47*13093SRoger.Faulkner@Oracle.COM  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48*13093SRoger.Faulkner@Oracle.COM  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49*13093SRoger.Faulkner@Oracle.COM  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50*13093SRoger.Faulkner@Oracle.COM  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
51*13093SRoger.Faulkner@Oracle.COM  * SUCH DAMAGE.
52*13093SRoger.Faulkner@Oracle.COM  */
53*13093SRoger.Faulkner@Oracle.COM 
54*13093SRoger.Faulkner@Oracle.COM #include <string.h>
55*13093SRoger.Faulkner@Oracle.COM 
56*13093SRoger.Faulkner@Oracle.COM /*
57*13093SRoger.Faulkner@Oracle.COM  * Find the first occurrence of the byte string s in byte string l.
58*13093SRoger.Faulkner@Oracle.COM  */
59*13093SRoger.Faulkner@Oracle.COM 
60*13093SRoger.Faulkner@Oracle.COM void *
memmem(const void * l,size_t l_len,const void * s,size_t s_len)61*13093SRoger.Faulkner@Oracle.COM memmem(const void *l, size_t l_len, const void *s, size_t s_len)
62*13093SRoger.Faulkner@Oracle.COM {
63*13093SRoger.Faulkner@Oracle.COM 	char *cur, *last;
64*13093SRoger.Faulkner@Oracle.COM 	const char *cl = (const char *)l;
65*13093SRoger.Faulkner@Oracle.COM 	const char *cs = (const char *)s;
66*13093SRoger.Faulkner@Oracle.COM 
67*13093SRoger.Faulkner@Oracle.COM 	/* we need something to compare */
68*13093SRoger.Faulkner@Oracle.COM 	if (l_len == 0 || s_len == 0)
69*13093SRoger.Faulkner@Oracle.COM 		return (NULL);
70*13093SRoger.Faulkner@Oracle.COM 
71*13093SRoger.Faulkner@Oracle.COM 	/* "s" must be smaller or equal to "l" */
72*13093SRoger.Faulkner@Oracle.COM 	if (l_len < s_len)
73*13093SRoger.Faulkner@Oracle.COM 		return (NULL);
74*13093SRoger.Faulkner@Oracle.COM 
75*13093SRoger.Faulkner@Oracle.COM 	/* special case where s_len == 1 */
76*13093SRoger.Faulkner@Oracle.COM 	if (s_len == 1)
77*13093SRoger.Faulkner@Oracle.COM 		return (memchr(l, (int)*cs, l_len));
78*13093SRoger.Faulkner@Oracle.COM 
79*13093SRoger.Faulkner@Oracle.COM 	/* the last position where its possible to find "s" in "l" */
80*13093SRoger.Faulkner@Oracle.COM 	last = (char *)cl + l_len - s_len;
81*13093SRoger.Faulkner@Oracle.COM 
82*13093SRoger.Faulkner@Oracle.COM 	for (cur = (char *)cl; cur <= last; cur++)
83*13093SRoger.Faulkner@Oracle.COM 		if (cur[0] == cs[0] && memcmp(cur, cs, s_len) == 0)
84*13093SRoger.Faulkner@Oracle.COM 			return (cur);
85*13093SRoger.Faulkner@Oracle.COM 
86*13093SRoger.Faulkner@Oracle.COM 	return (NULL);
87*13093SRoger.Faulkner@Oracle.COM }
88