1 /*	$NetBSD: strlcat.c,v 1.4 2013/01/23 07:57:27 matt Exp $	*/
2 /*	$OpenBSD: strlcat.c,v 1.10 2003/04/12 21:56:39 millert Exp $	*/
3 
4 /*
5  * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
6  *
7  * Permission to use, copy, modify, and distribute this software for any
8  * purpose with or without fee is hereby granted, provided that the above
9  * copyright notice and this permission notice appear in all copies.
10  *
11  * THE SOFTWARE IS PROVIDED "AS IS" AND TODD C. MILLER DISCLAIMS ALL
12  * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
13  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL TODD C. MILLER BE LIABLE
14  * FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
16  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
17  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18  */
19 
20 #include "config.h"
21 
22 #if defined(LIBC_SCCS) && !defined(lint)
23 __RCSID("$NetBSD: strlcat.c,v 1.4 2013/01/23 07:57:27 matt Exp $");
24 #endif /* LIBC_SCCS and not lint */
25 
26 #include <sys/types.h>
27 #include <assert.h>
28 #include <string.h>
29 
30 #ifdef _LIBC
31 # ifdef __weak_alias
__weak_alias(strlcat,_strlcat)32 __weak_alias(strlcat, _strlcat)
33 # endif
34 #endif
35 
36 #if !HAVE_STRLCAT
37 /*
38  * Appends src to string dst of size siz (unlike strncat, siz is the
39  * full size of dst, not space left).  At most siz-1 characters
40  * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
41  * Returns strlen(src) + MIN(siz, strlen(initial dst)).
42  * If retval >= siz, truncation occurred.
43  */
44 size_t
45 strlcat(char *dst, const char *src, size_t siz)
46 {
47 #if 1
48 	char *d = dst;
49 	const char *s = src;
50 	size_t n = siz;
51 	size_t dlen;
52 
53 	_DIAGASSERT(dst != NULL);
54 	_DIAGASSERT(src != NULL);
55 
56 	/* Find the end of dst and adjust bytes left but don't go past end */
57 	while (n-- != 0 && *d != '\0')
58 		d++;
59 	dlen = d - dst;
60 	n = siz - dlen;
61 
62 	if (n == 0)
63 		return(dlen + strlen(s));
64 	while (*s != '\0') {
65 		if (n != 1) {
66 			*d++ = *s;
67 			n--;
68 		}
69 		s++;
70 	}
71 	*d = '\0';
72 
73 	return(dlen + (s - src));	/* count does not include NUL */
74 #else
75 	_DIAGASSERT(dst != NULL);
76 	_DIAGASSERT(src != NULL);
77 
78 	/*
79 	 * Find length of string in dst (maxing out at siz).
80 	 */
81 	size_t dlen = strnlen(dst, siz);
82 
83 	/*
84 	 * Copy src into any remaining space in dst (truncating if needed).
85 	 * Note strlcpy(dst, src, 0) returns strlen(src).
86 	 */
87 	return dlen + strlcpy(dst + dlen, src, siz - dlen);
88 #endif
89 }
90 #endif
91