1 /* $OpenBSD: strlcat.c,v 1.5 2004/08/07 00:38:33 deraadt 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 #if defined(LIBC_SCCS) && !defined(lint)
20 static char *rcsid = "$OpenBSD: strlcat.c,v 1.5 2004/08/07 00:38:33 deraadt Exp $";
21 #endif /* LIBC_SCCS and not lint */
22
23 #if !defined(_KERNEL) && !defined(_STANDALONE)
24 #include <sys/types.h>
25 #include <string.h>
26 #else
27 #include <lib/libkern/libkern.h>
28 #endif
29
30 /*
31 * Appends src to string dst of size siz (unlike strncat, siz is the
32 * full size of dst, not space left). At most siz-1 characters
33 * will be copied. Always NUL terminates (unless siz <= strlen(dst)).
34 * Returns strlen(src) + MIN(siz, strlen(initial dst)).
35 * If retval >= siz, truncation occurred.
36 */
37 size_t
38 strlcat(char *dst, const char *src, size_t siz)
39 {
40 char *d = dst;
41 const char *s = src;
42 size_t n = siz;
43 size_t dlen;
44
45 /* Find the end of dst and adjust bytes left but don't go past end */
46 while (n-- != 0 && *d != '\0')
47 d++;
48 dlen = d - dst;
49 n = siz - dlen;
50
51 if (n == 0)
52 return(dlen + strlen(s));
53 while (*s != '\0') {
54 if (n != 1) {
55 *d++ = *s;
56 n--;
57 }
58 s++;
59 }
60 *d = '\0';
61
62 return(dlen + (s - src)); /* count does not include NUL */
63 }