1/*	$Id: compat_strlcat.c,v 1.6 2020/06/15 20:49:57 schwarze Exp $	*/
2/*	$OpenBSD: strlcat.c,v 1.19 2019/01/25 00:19:25 millert Exp $	*/
3
4/*
5 * Copyright (c) 1998, 2015 Todd C. Miller <millert@openbsd.org>
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 THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19#include "config.h"
20
21#include <sys/types.h>
22#include <string.h>
23
24/*
25 * Appends src to string dst of size dsize (unlike strncat, dsize is the
26 * full size of dst, not space left).  At most dsize-1 characters
27 * will be copied.  Always NUL terminates (unless dsize <= strlen(dst)).
28 * Returns strlen(src) + MIN(dsize, strlen(initial dst)).
29 * If retval >= dsize, truncation occurred.
30 */
31size_t
32strlcat(char *dst, const char *src, size_t dsize)
33{
34	const char *odst = dst;
35	const char *osrc = src;
36	size_t n = dsize;
37	size_t dlen;
38
39	/* Find the end of dst and adjust bytes left but don't go past end. */
40	while (n-- != 0 && *dst != '\0')
41		dst++;
42	dlen = dst - odst;
43	n = dsize - dlen;
44
45	if (n-- == 0)
46		return(dlen + strlen(src));
47	while (*src != '\0') {
48		if (n != 0) {
49			*dst++ = *src;
50			n--;
51		}
52		src++;
53	}
54	*dst = '\0';
55
56	return(dlen + (src - osrc));	/* count does not include NUL */
57}
58