1 /* $NetBSD: strncmp.c,v 1.2 2007/06/04 18:19:27 christos Exp $ */
2
3 /*
4 * Copyright (c) 1989, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 #if defined(LIBC_SCCS) && !defined(lint)
34 #if 0
35 static char sccsid[] = "@(#)strncmp.c 8.1 (Berkeley) 6/4/93";
36 #else
37 __RCSID("$NetBSD: strncmp.c,v 1.2 2007/06/04 18:19:27 christos Exp $");
38 #endif
39 #endif /* LIBC_SCCS and not lint */
40
41 #if !defined(_KERNEL) && !defined(_STANDALONE)
42 #include <assert.h>
43 #include <string.h>
44 #else
45 #include <lib/libkern/libkern.h>
46 #endif
47
48 int
strncmp(const char * s1,const char * s2,size_t n)49 strncmp(const char *s1, const char *s2, size_t n)
50 {
51
52 _DIAGASSERT(s1 != NULL);
53 _DIAGASSERT(s2 != NULL);
54
55 if (n == 0)
56 return (0);
57 do {
58 if (*s1 != *s2++)
59 return (*(const unsigned char *)s1 -
60 *(const unsigned char *)--s2);
61 if (*s1++ == 0)
62 break;
63 } while (--n != 0);
64 return (0);
65 }
66