xref: /freebsd/sys/libkern/strncpy.c (revision 685dc743dc3b5645e34836464128e1c0558b404b)
1df8bae1dSRodney W. Grimes /*-
251369649SPedro F. Giffuni  * SPDX-License-Identifier: BSD-3-Clause
351369649SPedro F. Giffuni  *
4df8bae1dSRodney W. Grimes  * Copyright (c) 1990, 1993
5df8bae1dSRodney W. Grimes  *	The Regents of the University of California.  All rights reserved.
6df8bae1dSRodney W. Grimes  *
7df8bae1dSRodney W. Grimes  * This code is derived from software contributed to Berkeley by
8df8bae1dSRodney W. Grimes  * Chris Torek.
9df8bae1dSRodney W. Grimes  *
10df8bae1dSRodney W. Grimes  * Redistribution and use in source and binary forms, with or without
11df8bae1dSRodney W. Grimes  * modification, are permitted provided that the following conditions
12df8bae1dSRodney W. Grimes  * are met:
13df8bae1dSRodney W. Grimes  * 1. Redistributions of source code must retain the above copyright
14df8bae1dSRodney W. Grimes  *    notice, this list of conditions and the following disclaimer.
15df8bae1dSRodney W. Grimes  * 2. Redistributions in binary form must reproduce the above copyright
16df8bae1dSRodney W. Grimes  *    notice, this list of conditions and the following disclaimer in the
17df8bae1dSRodney W. Grimes  *    documentation and/or other materials provided with the distribution.
18fbbd9655SWarner Losh  * 3. Neither the name of the University nor the names of its contributors
19df8bae1dSRodney W. Grimes  *    may be used to endorse or promote products derived from this software
20df8bae1dSRodney W. Grimes  *    without specific prior written permission.
21df8bae1dSRodney W. Grimes  *
22df8bae1dSRodney W. Grimes  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23df8bae1dSRodney W. Grimes  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24df8bae1dSRodney W. Grimes  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25df8bae1dSRodney W. Grimes  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26df8bae1dSRodney W. Grimes  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27df8bae1dSRodney W. Grimes  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28df8bae1dSRodney W. Grimes  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29df8bae1dSRodney W. Grimes  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30df8bae1dSRodney W. Grimes  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31df8bae1dSRodney W. Grimes  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32df8bae1dSRodney W. Grimes  * SUCH DAMAGE.
33df8bae1dSRodney W. Grimes  */
34df8bae1dSRodney W. Grimes 
35ab0de15bSDavid E. O'Brien #include <sys/cdefs.h>
36452bffb2SJohn Baldwin #include <sys/libkern.h>
37df8bae1dSRodney W. Grimes 
38df8bae1dSRodney W. Grimes /*
39df8bae1dSRodney W. Grimes  * Copy src to dst, truncating or null-padding to always copy n bytes.
40df8bae1dSRodney W. Grimes  * Return dst.
41df8bae1dSRodney W. Grimes  */
42df8bae1dSRodney W. Grimes char *
strncpy(char * __restrict dst,const char * __restrict src,size_t n)4393eb73aaSJeffrey Hsu strncpy(char * __restrict dst, const char * __restrict src, size_t n)
44df8bae1dSRodney W. Grimes {
45df8bae1dSRodney W. Grimes 	if (n != 0) {
46484820d4SConrad Meyer 		char *d = dst;
47484820d4SConrad Meyer 		const char *s = src;
48df8bae1dSRodney W. Grimes 
49df8bae1dSRodney W. Grimes 		do {
50*85b64892SEd Maste 			if ((*d++ = *s++) == '\0') {
51df8bae1dSRodney W. Grimes 				/* NUL pad the remaining n-1 bytes */
52df8bae1dSRodney W. Grimes 				while (--n != 0)
53*85b64892SEd Maste 					*d++ = '\0';
54df8bae1dSRodney W. Grimes 				break;
55df8bae1dSRodney W. Grimes 			}
56df8bae1dSRodney W. Grimes 		} while (--n != 0);
57df8bae1dSRodney W. Grimes 	}
58df8bae1dSRodney W. Grimes 	return (dst);
59df8bae1dSRodney W. Grimes }
60