lib/localename-table.h

   1 /* Table that maps a locale object to the names of the locale categories.
   2    Copyright (C) 2018-2024 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as published by
   6    the Free Software Foundation; either version 2.1 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Bruno Haible <bruno@clisp.org>, 2018.  */
  18
  19 #if HAVE_WORKING_USELOCALE && HAVE_NAMELESS_LOCALES
  20
  21 # include <stddef.h>
  22 # include <locale.h>
  23
  24 # include "glthread/lock.h"
  25
  26 struct locale_categories_names
  27   {
  28     /* Locale category -> name (allocated with indefinite extent).  */
  29     const char *category_name[6];
  30   };
  31
  32 /* A hash table of fixed size.  Multiple threads can access it read-only
  33    simultaneously, but only one thread can insert into it or remove from it
  34    at the same time.
  35    This hash table has global scope, so that when an application uses both
  36    GNU libintl and gnulib, the application sees only one hash table.  (When
  37    linking statically with libintl, the fact that localename-table.c is a
  38    separate compilation unit resolves the duplicate symbol conflict.  When
  39    linking with libintl as a shared library, we rely on ELF and the symbol
  40    conflict resolution implemented in the ELF dynamic loader here.)
  41    Both the libintl overrides and the gnulib overrides of the functions
  42    newlocale, duplocale, freelocale see the same hash table (and the same lock).
  43    For this reason, the internal layout of the hash table and the hash function
  44    MUST NEVER CHANGE.  If you need to change the internal layout or the hash
  45    function, introduce versioning by appending a version suffix to the symbols
  46    at the linker level.  */
  47 # define locale_hash_function libintl_locale_hash_function
  48 # define locale_hash_table libintl_locale_hash_table
  49 # define locale_lock libintl_locale_lock
  50
  51 extern size_t _GL_ATTRIBUTE_CONST locale_hash_function (locale_t x);
  52
  53 /* A node in a hash bucket collision list.  */
  54 struct locale_hash_node
  55   {
  56     struct locale_hash_node *next;
  57     locale_t locale;
  58     struct locale_categories_names names;
  59   };
  60
  61 # define LOCALE_HASH_TABLE_SIZE 101
  62 extern struct locale_hash_node * locale_hash_table[LOCALE_HASH_TABLE_SIZE];
  63
  64 /* This lock protects the locale_hash_table against multiple simultaneous
  65    accesses (except that multiple simultaneous read accesses are allowed).  */
  66
  67 gl_rwlock_define(extern, locale_lock)
  68
  69 #endif