1 /*        $NetBSD: strlcat.c,v 1.5 2024/11/01 21:11:37 riastradh 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_NBTOOL_CONFIG_H
22 #include "nbtool_config.h"
23 #endif
24 
25 #include <sys/cdefs.h>
26 #if defined(LIBC_SCCS) && !defined(lint)
27 __RCSID("$NetBSD: strlcat.c,v 1.5 2024/11/01 21:11:37 riastradh Exp $");
28 #endif /* LIBC_SCCS and not lint */
29 
30 #ifdef _LIBC
31 #include "namespace.h"
32 #endif
33 #include <sys/types.h>
34 #include <assert.h>
35 #include <string.h>
36 
37 #ifdef _LIBC
38 # ifdef __weak_alias
__weak_alias(strlcat,_strlcat)39 __weak_alias(strlcat, _strlcat)
40 # endif
41 #endif
42 
43 #else
44 #include <lib/libkern/libkern.h>
45 #endif /* !_KERNEL && !_STANDALONE */
46 
47 #if !HAVE_STRLCAT
48 /*
49  * Appends src to string dst of size siz (unlike strncat, siz is the
50  * full size of dst, not space left).  At most siz-1 characters
51  * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
52  * Returns strlen(src) + MIN(siz, strlen(initial dst)).
53  * If retval >= siz, truncation occurred.
54  */
55 size_t
56 strlcat(char *__restrict dst, const char *__restrict src, size_t siz)
57 {
58 #if 1
59           char *d = dst;
60           const char *s = src;
61           size_t n = siz;
62           size_t dlen;
63 
64           _DIAGASSERT(dst != NULL);
65           _DIAGASSERT(src != NULL);
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           _DIAGASSERT(dst != NULL);
87           _DIAGASSERT(src != NULL);
88 
89           /*
90            * Find length of string in dst (maxing out at siz).
91            */
92           size_t dlen = strnlen(dst, siz);
93 
94           /*
95            * Copy src into any remaining space in dst (truncating if needed).
96            * Note strlcpy(dst, src, 0) returns strlen(src).
97            */
98           return dlen + strlcpy(dst + dlen, src, siz - dlen);
99 #endif
100 }
101 #endif
102