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strnstr.c revision 1.1 
      1 /*	$NetBSD: strnstr.c,v 1.1 2014/09/24 22:21:33 christos Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2001 Mike Barcroft <mike (at) 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 }
     72