1 /* $OpenBSD: strlcat.c,v 1.15 2015/03/02 21:41:08 millert Exp $ */
2
3 /*
4 * SPDX-License-Identifier: ISC
5 *
6 * Copyright (c) 1998, 2015 Todd C. Miller <Todd.Miller@courtesan.com>
7 *
8 * Permission to use, copy, modify, and distribute this software for any
9 * purpose with or without fee is hereby granted, provided that the above
10 * copyright notice and this permission notice appear in all copies.
11 *
12 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
13 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
14 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
15 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
16 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
17 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
18 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
19 */
20
21 #include <string.h>
22
23 /*
24 * Appends src to string dst of size dsize (unlike strncat, dsize is the
25 * full size of dst, not space left). At most dsize-1 characters
26 * will be copied. Always NUL terminates (unless dsize <= strlen(dst)).
27 * Returns strlen(src) + MIN(dsize, strlen(initial dst)).
28 * If retval >= dsize, truncation occurred.
29 */
30 size_t
strlcat(char * dst,const char * src,size_t dsize)31 strlcat(char * dst, const char * src, size_t dsize)
32 {
33 const char *odst = dst;
34 const char *osrc = src;
35 size_t n = dsize;
36 size_t dlen;
37
38 /* Find the end of dst and adjust bytes left but don't go past end. */
39 while (n-- != 0 && *dst != '\0')
40 dst++;
41 dlen = dst - odst;
42 n = dsize - dlen;
43
44 if (n-- == 0)
45 return(dlen + strlen(src));
46 while (*src != '\0') {
47 if (n != 0) {
48 *dst++ = *src;
49 n--;
50 }
51 src++;
52 }
53 *dst = '\0';
54
55 return(dlen + (src - osrc)); /* count does not include NUL */
56 }
57