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 <stdio.h>
22 #include <string.h>
23
24 #include <ssp/string.h>
25
26 /*
27 * Appends src to string dst of size dsize (unlike strncat, dsize is the
28 * full size of dst, not space left). At most dsize-1 characters
29 * will be copied. Always NUL terminates (unless dsize <= strlen(dst)).
30 * Returns strlen(src) + MIN(dsize, strlen(initial dst)).
31 * If retval >= dsize, truncation occurred.
32 */
33 size_t
__strlcat_chk(char * __restrict dst,const char * __restrict src,size_t dsize,size_t dbufsize)34 __strlcat_chk(char * __restrict dst, const char * __restrict src, size_t dsize,
35 size_t dbufsize)
36 {
37 const char *odst = dst;
38 const char *osrc = src;
39 size_t n = dsize;
40 size_t dlen;
41
42 if (dsize > dbufsize)
43 __chk_fail();
44
45 /* Find the end of dst and adjust bytes left but don't go past end. */
46 while (n-- != 0 && *dst != '\0') {
47 dst++;
48 }
49
50 dlen = dst - odst;
51 n = dsize - dlen;
52
53 if (n-- == 0)
54 return (dlen + strlen(src));
55 while (*src != '\0') {
56 if (n != 0) {
57 if (dbufsize-- == 0)
58 __chk_fail();
59 *dst++ = *src;
60 n--;
61 }
62
63 src++;
64 }
65
66 if (dbufsize-- == 0)
67 __chk_fail();
68 *dst = '\0';
69 return (dlen + (src - osrc)); /* count does not include NUL */
70 }
71