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b54e5d1c | 1 | /* Append a null-terminated wide string to another, with length checking. |
dff8da6b | 2 | Copyright (C) 2023-2024 Free Software Foundation, Inc. |
b54e5d1c FW |
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 | ||
22 | size_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 | } | |
59 | libc_hidden_def (__wcslcat) | |
60 | weak_alias (__wcslcat, wcslcat) |