strlcat.c revision 356341 
1/*	$OpenBSD: pcap_strlcat.c,v 1.15 2015/03/02 21:41:08 millert Exp $	*/
2
3/*
4 * Copyright (c) 1998, 2015 Todd C. Miller <Todd.Miller@courtesan.com>
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#ifdef HAVE_CONFIG_H
20#include <config.h>
21#endif
22
23#include <stddef.h>
24#include <string.h>
25
26#include "portability.h"
27
28/*
29 * Appends src to string dst of size dsize (unlike strncat, dsize is the
30 * full size of dst, not space left).  At most dsize-1 characters
31 * will be copied.  Always NUL terminates (unless dsize <= strlen(dst)).
32 * Returns strlen(src) + MIN(dsize, strlen(initial dst)).
33 * If retval >= dsize, truncation occurred.
34 */
35size_t
36pcap_strlcat(char * restrict dst, const char * restrict src, size_t dsize)
37{
38	const char *odst = dst;
39	const char *osrc = src;
40	size_t n = dsize;
41	size_t dlen;
42
43	/* Find the end of dst and adjust bytes left but don't go past end. */
44	while (n-- != 0 && *dst != '\0')
45		dst++;
46	dlen = dst - odst;
47	n = dsize - dlen;
48
49	if (n-- == 0)
50		return(dlen + strlen(src));
51	while (*src != '\0') {
52		if (n != 0) {
53			*dst++ = *src;
54			n--;
55		}
56		src++;
57	}
58	*dst = '\0';
59
60	return(dlen + (src - osrc));	/* count does not include NUL */
61}
62