xref: /netbsd-src/external/bsd/file/dist/src/strcasestr.c (revision b7b7574d3bf8eeb51a1fa3977b59142ec6434a55)
1 /*	$NetBSD: strcasestr.c,v 1.1.1.1 2014/06/13 01:48:21 christos Exp $	*/
2 /*	NetBSD: strcasestr.c,v 1.3 2005/11/29 03:12:00 christos Exp 	*/
3 
4 /*-
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 #if defined(LIBC_SCCS) && !defined(lint)
37 __RCSID("NetBSD: strcasestr.c,v 1.3 2005/11/29 03:12:00 christos Exp ");
38 __RCSID("NetBSD: strncasecmp.c,v 1.2 2007/06/04 18:19:27 christos Exp ");
39 #endif /* LIBC_SCCS and not lint */
40 
41 #include "file.h"
42 
43 #include <assert.h>
44 #include <ctype.h>
45 #include <string.h>
46 
47 static int
48 _strncasecmp(const char *s1, const char *s2, size_t n)
49 {
50 	if (n != 0) {
51 		const unsigned char *us1 = (const unsigned char *)s1,
52 				*us2 = (const unsigned char *)s2;
53 
54 		do {
55 			if (tolower(*us1) != tolower(*us2++))
56 				return tolower(*us1) - tolower(*--us2);
57 			if (*us1++ == '\0')
58 				break;
59 		} while (--n != 0);
60 	}
61 	return 0;
62 }
63 
64 /*
65  * Find the first occurrence of find in s, ignore case.
66  */
67 char *
68 strcasestr(const char *s, const char *find)
69 {
70 	char c, sc;
71 	size_t len;
72 
73 	if ((c = *find++) != 0) {
74 		c = tolower((unsigned char)c);
75 		len = strlen(find);
76 		do {
77 			do {
78 				if ((sc = *s++) == 0)
79 					return (NULL);
80 			} while ((char)tolower((unsigned char)sc) != c);
81 		} while (_strncasecmp(s, find, len) != 0);
82 		s--;
83 	}
84 	return (char *)(intptr_t)(s);
85 }
86