1/* Append a null-terminated wide string to another, with length checking.
2 Copyright (C) 2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <stdint.h>
20#include <wchar.h>
21
22size_t
23__wcslcat (wchar_t *__restrict dest, const wchar_t *__restrict src,
24 size_t size)
25{
26 size_t src_length = __wcslen (src);
27
28 /* Our implementation strlcat supports dest == NULL if size == 0
29 (for consistency with snprintf and strlcpy), but wcsnlen does
30 not, so we have to cover this case explicitly. */
31 if (size == 0)
32 return src_length;
33
34 size_t dest_length = __wcsnlen (dest, size);
35 if (dest_length != size)
36 {
37 /* Copy at most the remaining number of characters in the
38 destination buffer. Leave for the null terminator. */
39 size_t to_copy = size - dest_length - 1;
40 /* But not more than what is available in the source string. */
41 if (to_copy > src_length)
42 to_copy = src_length;
43
44 wchar_t *target = dest + dest_length;
45 __wmemcpy (target, src, to_copy);
46 target[to_copy] = '\0';
47 }
48
49 /* If the sum wraps around, we have more than SIZE_MAX + 2 bytes in
50 the two input strings (including both null terminators). If each
51 byte in the address space can be assigned a unique size_t value
52 (which the static_assert checks), then by the pigeonhole
53 principle, the two input strings must overlap, which is
54 undefined. */
55 _Static_assert (sizeof (uintptr_t) == sizeof (size_t),
56 "theoretical maximum object size covers address space");
57 return dest_length + src_length;
58}
59libc_hidden_def (__wcslcat)
60weak_alias (__wcslcat, wcslcat)
61