1/* uselocale -- fetch and set the current per-thread locale
2 Copyright (C) 2002-2021 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 <locale.h>
20#include "localeinfo.h"
21#include <ctype.h>
22
23/* Switch the current thread's locale to DATASET.
24 If DATASET is null, instead just return the current setting.
25 The special value LC_GLOBAL_LOCALE is the initial setting
26 for all threads, and means the thread uses the global
27 setting controlled by `setlocale'. */
28locale_t
29__uselocale (locale_t newloc)
30{
31 locale_t oldloc = _NL_CURRENT_LOCALE;
32
33 if (newloc != NULL)
34 {
35 const locale_t locobj
36 = newloc == LC_GLOBAL_LOCALE ? &_nl_global_locale : newloc;
37 __libc_tsd_set (locale_t, LOCALE, locobj);
38
39#ifdef NL_CURRENT_INDIRECT
40 /* Now we must update all the per-category thread-local variables to
41 point into the new current locale for this thread. The magic
42 symbols _nl_current_LC_FOO_used are defined to meaningless values
43 if _nl_current_LC_FOO was linked in. By using weak references to
44 both symbols and testing the address of _nl_current_LC_FOO_used,
45 we can avoid accessing the _nl_current_LC_FOO thread-local
46 variable at all when no code referring to it was linked in. We
47 need the special bogus symbol because while TLS symbols can be
48 weak, there is no reasonable way to test for the default-zero
49 value as with a heap symbol (taking the address would just use
50 some bogus offset from our thread pointer). */
51
52# define DEFINE_CATEGORY(category, category_name, items, a) \
53 { \
54 extern char _nl_current_##category##_used; \
55 weak_extern (_nl_current_##category##_used) \
56 weak_extern (_nl_current_##category) \
57 if (&_nl_current_##category##_used != 0) \
58 _nl_current_##category = &locobj->__locales[category]; \
59 }
60# include "categories.def"
61# undef DEFINE_CATEGORY
62#endif
63
64 /* Update the special tsd cache of some locale data. */
65 __libc_tsd_set (const uint16_t *, CTYPE_B, (void *) locobj->__ctype_b);
66 __libc_tsd_set (const int32_t *, CTYPE_TOLOWER,
67 (void *) locobj->__ctype_tolower);
68 __libc_tsd_set (const int32_t *, CTYPE_TOUPPER,
69 (void *) locobj->__ctype_toupper);
70 }
71
72 return oldloc == &_nl_global_locale ? LC_GLOBAL_LOCALE : oldloc;
73}
74libc_hidden_def (__uselocale)
75weak_alias (__uselocale, uselocale)
76