usr/src/lib/libc/port/gen/memmem.c

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