/* uselocale -- fetch and set the current per-thread locale

   Copyright (C) 2002-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <locale.h>

#include "localeinfo.h"

#include <ctype.h>

/* Switch the current thread's locale to DATASET.

   If DATASET is null, instead just return the current setting.

   The special value LC_GLOBAL_LOCALE is the initial setting

   for all threads, and means the thread uses the global

   setting controlled by `setlocale'.  */

locale_t

__uselocale (locale_t newloc)

{

  locale_t oldloc = _NL_CURRENT_LOCALE;

  if (newloc != NULL)

    {

      const locale_t locobj

	= newloc == LC_GLOBAL_LOCALE ? &_nl_global_locale : newloc;

      __libc_tsd_set (locale_t, LOCALE, locobj);

#ifdef NL_CURRENT_INDIRECT

      /* Now we must update all the per-category thread-local variables to

	 point into the new current locale for this thread.  The magic

	 symbols _nl_current_LC_FOO_used are defined to meaningless values

	 if _nl_current_LC_FOO was linked in.  By using weak references to

	 both symbols and testing the address of _nl_current_LC_FOO_used,

	 we can avoid accessing the _nl_current_LC_FOO thread-local

	 variable at all when no code referring to it was linked in.  We

	 need the special bogus symbol because while TLS symbols can be

	 weak, there is no reasonable way to test for the default-zero

	 value as with a heap symbol (taking the address would just use

	 some bogus offset from our thread pointer).  */

# define DEFINE_CATEGORY(category, category_name, items, a) \

      {									      \

	extern char _nl_current_##category##_used;			      \

	weak_extern (_nl_current_##category##_used)			      \

	weak_extern (_nl_current_##category)				      \

	if (&_nl_current_##category##_used != 0)			      \

	  _nl_current_##category = &locobj->__locales[category];	      \

      }

# include "categories.def"

# undef	DEFINE_CATEGORY

#endif

      /* Update the special tsd cache of some locale data.  */

      __libc_tsd_set (const uint16_t *, CTYPE_B, (void *) locobj->__ctype_b);

      __libc_tsd_set (const int32_t *, CTYPE_TOLOWER,

		      (void *) locobj->__ctype_tolower);

      __libc_tsd_set (const int32_t *, CTYPE_TOUPPER,

		      (void *) locobj->__ctype_toupper);

    }

  return oldloc == &_nl_global_locale ? LC_GLOBAL_LOCALE : oldloc;

}

libc_hidden_def (__uselocale)

weak_alias (__uselocale, uselocale)