xref: /dragonfly/lib/libc/string/strlcat.c (revision 2cd2d2b5)
1 /*
2  * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. The name of the author may not be used to endorse or promote products
14  *    derived from this software without specific prior written permission.
15  *
16  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
17  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
18  * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
19  * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
20  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26  *
27  * $OpenBSD: strlcat.c,v 1.2 1999/06/17 16:28:58 millert Exp $
28  * $FreeBSD: src/lib/libc/string/strlcat.c,v 1.2.4.2 2001/07/09 23:30:06 obrien Exp $
29  * $DragonFly: src/lib/libc/string/strlcat.c,v 1.2 2003/06/17 04:26:46 dillon Exp $
30  */
31 
32 #include <sys/types.h>
33 #include <string.h>
34 
35 /*
36  * Appends src to string dst of size siz (unlike strncat, siz is the
37  * full size of dst, not space left).  At most siz-1 characters
38  * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
39  * Returns strlen(initial dst) + strlen(src); if retval >= siz,
40  * truncation occurred.
41  */
42 size_t strlcat(dst, src, siz)
43 	char *dst;
44 	const char *src;
45 	size_t siz;
46 {
47 	register char *d = dst;
48 	register const char *s = src;
49 	register size_t n = siz;
50 	size_t dlen;
51 
52 	/* Find the end of dst and adjust bytes left but don't go past end */
53 	while (n-- != 0 && *d != '\0')
54 		d++;
55 	dlen = d - dst;
56 	n = siz - dlen;
57 
58 	if (n == 0)
59 		return(dlen + strlen(s));
60 	while (*s != '\0') {
61 		if (n != 1) {
62 			*d++ = *s;
63 			n--;
64 		}
65 		s++;
66 	}
67 	*d = '\0';
68 
69 	return(dlen + (s - src));	/* count does not include NUL */
70 }
71