1 /* $OpenBSD: strlcat.c,v 1.19 2019/01/25 00:19:25 millert Exp $ */
2
3 /*
4 * Copyright (c) 1998, 2015 Todd C. Miller <millert@openbsd.org>
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 #define _DEFAULT_SOURCE
20 #include <sys/types.h>
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,
32 const char *src,
33 size_t dsize)
34 {
35 const char *odst = dst;
36 const char *osrc = src;
37 size_t n = dsize;
38 size_t dlen;
39
40 /* Find the end of dst and adjust bytes left but don't go past end. */
41 while (n-- != 0 && *dst != '\0')
42 dst++;
43 dlen = dst - odst;
44 n = dsize - dlen;
45
46 if (n-- == 0)
47 return(dlen + strlen(src));
48 while (*src != '\0') {
49 if (n != 0) {
50 *dst++ = *src;
51 n--;
52 }
53 src++;
54 }
55 *dst = '\0';
56
57 return(dlen + (src - osrc)); /* count does not include NUL */
58 }
59
