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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 #include <sys/types.h>
20 #include <string.h>
21 
22 /*
23  * Appends src to string dst of size siz (unlike strncat, siz is the
24  * full size of dst, not space left).  At most siz-1 characters
25  * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
26  * Returns strlen(src) + MIN(siz, strlen(initial dst)).
27  * If retval >= siz, truncation occurred.
28  */
29 size_t
strlcat(char * dst,const char * src,size_t siz)30 strlcat(char *dst, const char *src, size_t siz)
31 {
32 	char *d = dst;
33 	const char *s = src;
34 	size_t n = siz;
35 	size_t dlen;
36 
37 	/* Find the end of dst and adjust bytes left but don't go past end */
38 	while (n-- != 0 && *d != '\0')
39 		d++;
40 	dlen = d - dst;
41 	n = siz - dlen;
42 
43 	if (n == 0)
44 		return(dlen + strlen(s));
45 	while (*s != '\0') {
46 		if (n != 1) {
47 			*d++ = *s;
48 			n--;
49 		}
50 		s++;
51 	}
52 	*d = '\0';
53 
54 	return(dlen + (s - src));	/* count does not include NUL */
55 }
56