strlcat.c revision 284194 
1/*	$OpenBSD: strlcat.c,v 1.13 2005/08/08 08:05:37 espie Exp $	*/
2
3/*
4 * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19/* OPENBSD ORIGINAL: lib/libc/string/strlcat.c */
20#include "file.h"
21
22#include <sys/types.h>
23#include <string.h>
24
25/*
26 * Appends src to string dst of size siz (unlike strncat, siz is the
27 * full size of dst, not space left).  At most siz-1 characters
28 * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
29 * Returns strlen(src) + MIN(siz, strlen(initial dst)).
30 * If retval >= siz, truncation occurred.
31 */
32size_t
33strlcat(char *dst, const char *src, size_t siz)
34{
35	char *d = dst;
36	const char *s = src;
37	size_t n = siz;
38	size_t dlen;
39
40	/* Find the end of dst and adjust bytes left but don't go past end */
41	while (n-- != 0 && *d != '\0')
42		d++;
43	dlen = d - dst;
44	n = siz - dlen;
45
46	if (n == 0)
47		return(dlen + strlen(s));
48	while (*s != '\0') {
49		if (n != 1) {
50			*d++ = *s;
51			n--;
52		}
53		s++;
54	}
55	*d = '\0';
56
57	return(dlen + (s - src));	/* count does not include NUL */
58}
59