1 /* $OpenBSD: strncpy.c,v 1.7 2004/11/28 07:23:41 mickey Exp $ */
2
3 /*-
4 * Copyright (c) 1990 The Regents of the University of California.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char *rcsid = "$OpenBSD: strncpy.c,v 1.7 2004/11/28 07:23:41 mickey Exp $";
37 #endif /* LIBC_SCCS and not lint */
38
39 #if !defined(_KERNEL) && !defined(_STANDALONE)
40 #include <string.h>
41 #else
42 #include <lib/libkern/libkern.h>
43 #endif
44
45 /*
46 * Copy src to dst, truncating or null-padding to always copy n bytes.
47 * Return dst.
48 */
49 char *
50 strncpy(char *dst, const char *src, size_t n)
51 {
52 if (n != 0) {
53 char *d = dst;
54 const char *s = src;
55
56 do {
57 if ((*d++ = *s++) == 0) {
58 /* NUL pad the remaining n-1 bytes */
59 while (--n != 0)
60 *d++ = 0;
61 break;
62 }
63 } while (--n != 0);
64 }
65 return (dst);
66 }