strlcat.c revision 49594 
1/*	$OpenBSD: strlcat.c,v 1.2 1999/06/17 16:28:58 millert Exp $	*/
2
3/*
4 * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
5 * 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. The name of the author may not be used to endorse or promote products
16 *    derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
19 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
20 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
21 * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
22 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
23 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
24 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
25 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
26 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
27 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30#if defined(LIBC_SCCS) && !defined(lint)
31static char *rcsid = "$OpenBSD: strlcat.c,v 1.2 1999/06/17 16:28:58 millert Exp $";
32#endif /* LIBC_SCCS and not lint */
33
34#include <sys/types.h>
35#include <string.h>
36
37/*
38 * Appends src to string dst of size siz (unlike strncat, siz is the
39 * full size of dst, not space left).  At most siz-1 characters
40 * will be copied.  Always NUL terminates (unless siz == 0).
41 * Returns strlen(src); if retval >= siz, truncation occurred.
42 */
43size_t strlcat(dst, src, siz)
44	char *dst;
45	const char *src;
46	size_t siz;
47{
48	register char *d = dst;
49	register const char *s = src;
50	register size_t n = siz;
51	size_t dlen;
52
53	/* Find the end of dst and adjust bytes left but don't go past end */
54	while (*d != '\0' && n-- != 0)
55		d++;
56	dlen = d - dst;
57	n = siz - dlen;
58
59	if (n == 0)
60		return(dlen + strlen(s));
61	while (*s != '\0') {
62		if (n != 1) {
63			*d++ = *s;
64			n--;
65		}
66		s++;
67	}
68	*d = '\0';
69
70	return(dlen + (s - src));	/* count does not include NUL */
71}
72