1 /* $NetBSD: strlcat.c,v 1.2 2025/02/11 17:48:30 christos Exp $ */
2 /* $OpenBSD: strlcat.c,v 1.10 2003/04/12 21:56:39 millert Exp $ */
3
4 /*
5 * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
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 TODD C. MILLER DISCLAIMS ALL
12 * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
13 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL TODD C. MILLER BE LIABLE
14 * FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
16 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
17 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20 #if !defined(_KERNEL) && !defined(_STANDALONE)
21 #if HAVE_CONFIG_H
22 #include "config.h"
23 #endif
24
25 #ifdef HAVE_SYS_CDEFS_H
26 #include <sys/cdefs.h>
27 #endif
28
29 #if defined(LIBC_SCCS) && !defined(lint)
30 __RCSID("$NetBSD: strlcat.c,v 1.2 2025/02/11 17:48:30 christos Exp $");
31 #endif /* LIBC_SCCS and not lint */
32
33 #ifdef _LIBC
34 #include "namespace.h"
35 #endif
36 #include <sys/types.h>
37 #include <assert.h>
38 #include <string.h>
39
40 #ifdef _LIBC
41 # ifdef __weak_alias
__weak_alias(strlcat,_strlcat)42 __weak_alias(strlcat, _strlcat)
43 # endif
44 #endif
45
46 #else
47 #include <lib/libkern/libkern.h>
48 #endif /* !_KERNEL && !_STANDALONE */
49
50 #if !HAVE_STRLCAT
51 /*
52 * Appends src to string dst of size siz (unlike strncat, siz is the
53 * full size of dst, not space left). At most siz-1 characters
54 * will be copied. Always NUL terminates (unless siz <= strlen(dst)).
55 * Returns strlen(src) + MIN(siz, strlen(initial dst)).
56 * If retval >= siz, truncation occurred.
57 */
58 size_t
59 strlcat(char *dst, const char *src, size_t siz)
60 {
61 #if 1
62 char *d = dst;
63 const char *s = src;
64 size_t n = siz;
65 size_t dlen;
66
67 /* Find the end of dst and adjust bytes left but don't go past end */
68 while (n-- != 0 && *d != '\0')
69 d++;
70 dlen = d - dst;
71 n = siz - dlen;
72
73 if (n == 0)
74 return(dlen + strlen(s));
75 while (*s != '\0') {
76 if (n != 1) {
77 *d++ = *s;
78 n--;
79 }
80 s++;
81 }
82 *d = '\0';
83
84 return(dlen + (s - src)); /* count does not include NUL */
85 #else
86
87 /*
88 * Find length of string in dst (maxing out at siz).
89 */
90 size_t dlen = strnlen(dst, siz);
91
92 /*
93 * Copy src into any remaining space in dst (truncating if needed).
94 * Note strlcpy(dst, src, 0) returns strlen(src).
95 */
96 return dlen + strlcpy(dst + dlen, src, siz - dlen);
97 #endif
98 }
99 #endif
100