xref: /dragonfly/sys/libkern/strlcat.c (revision 86d7f5d3)
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/sys/libkern/strlcat.c,v 1.5 2007/06/07 23:45:02 dillon Exp $
30  */
31 
32 #include <sys/types.h>
33 #include <sys/libkern.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(char * dst,const char * src,size_t siz)43 strlcat(char *dst, const char *src, size_t siz)
44 {
45 	char *d = dst;
46 	const char *s = src;
47 	size_t n = siz;
48 	size_t dlen;
49 
50 	/* Find the end of dst and adjust bytes left but don't go past end */
51 	while (n-- != 0 && *d != '\0')
52 		d++;
53 	dlen = d - dst;
54 	n = siz - dlen;
55 
56 	if (n == 0)
57 		return(dlen + strlen(s));
58 	while (*s != '\0') {
59 		if (n != 1) {
60 			*d++ = *s;
61 			n--;
62 		}
63 		s++;
64 	}
65 	*d = '\0';
66 
67 	return(dlen + (s - src));	/* count does not include NUL */
68 }
69