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 1/*	$OpenBSD: 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#include <string.h>
20#include <sys/types.h>
21
22#include "compat.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 strlcat(char *dst, const char *src, size_t dsize) {
32  const char *odst = dst;
33  const char *osrc = src;
34  size_t n = dsize;
35  size_t dlen;
36
37  /* Find the end of dst and adjust bytes left but don't go past end. */
38  while (n-- != 0 && *dst != '\0')
39    dst++;
40  dlen = dst - odst;
41  n = dsize - dlen;
42
43  if (n-- == 0)
44    return (dlen + strlen(src));
45  while (*src != '\0') {
46    if (n != 0) {
47      *dst++ = *src;
48      n--;
49    }
50    src++;
51  }
52  *dst = '\0';
53
54  return (dlen + (src - osrc)); /* count does not include NUL */
55}