lib/libc/string/strnstr.c

   1 /*      $NetBSD: strnstr.c,v 1.1 2014/09/24 22:21:33 christos Exp $     */
   2
   3 /*-
   4  * Copyright (c) 2001 Mike Barcroft <mike@FreeBSD.org>
   5  * Copyright (c) 1990, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * This code is derived from software contributed to Berkeley by
   9  * Chris Torek.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  */
  35
  36 #include <sys/cdefs.h>
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 #if 0
  39 static char sccsid[] = "@(#)strstr.c    8.1 (Berkeley) 6/4/93";
  40 #else
  41 __RCSID("$NetBSD: strnstr.c,v 1.1 2014/09/24 22:21:33 christos Exp $");
  42 #endif
  43 #endif /* LIBC_SCCS and not lint */
  44 /* FreeBSD: head/lib/libc/string/strnstr.c 251069 2013-05-28 20:57:40Z emaste */
  45
  46 #include <string.h>
  47
  48 /*
  49  * Find the first occurrence of find in s, where the search is limited to the
  50  * first slen characters of s.
  51  */
  52 char *
  53 strnstr(const char *s, const char *find, size_t slen)
  54 {
  55         char c, sc;
  56         size_t len;
  57
  58         if ((c = *find++) != '\0') {
  59                 len = strlen(find);
  60                 do {
  61                         do {
  62                                 if (slen-- < 1 || (sc = *s++) == '\0')
  63                                         return NULL;
  64                         } while (sc != c);
  65                         if (len > slen)
  66                                 return NULL;
  67                 } while (strncmp(s, find, len) != 0);
  68                 s--;
  69         }
  70         return __UNCONST(s);
  71 }