intl/localcharset.c

   1 /* Determine a canonical name for the current locale's character encoding.
   2
   3    Copyright (C) 2000-2003 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify it
   6    under the terms of the GNU Library General Public License as published
   7    by the Free Software Foundation; either version 2, or (at your option)
   8    any later version.
   9
  10    This program 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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with this program; if not, write to the Free Software
  17    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301,
  18    USA.  */
  19
  20 /* Written by Bruno Haible <bruno@clisp.org>.  */
  21
  22 #ifdef HAVE_CONFIG_H
  23 # include <config.h>
  24 #endif
  25
  26 /* Specification.  */
  27 #include "localcharset.h"
  28
  29 #if HAVE_STDDEF_H
  30 # include <stddef.h>
  31 #endif
  32
  33 #include <stdio.h>
  34 #if HAVE_STRING_H
  35 # include <string.h>
  36 #else
  37 # include <strings.h>
  38 #endif
  39 #if HAVE_STDLIB_H
  40 # include <stdlib.h>
  41 #endif
  42
  43 #if defined _WIN32 || defined __WIN32__
  44 # undef WIN32   /* avoid warning on mingw32 */
  45 # define WIN32
  46 #endif
  47
  48 #if defined __EMX__
  49 /* Assume EMX program runs on OS/2, even if compiled under DOS.  */
  50 # define OS2
  51 #endif
  52
  53 #if !defined WIN32
  54 # if HAVE_LANGINFO_CODESET
  55 #  include <langinfo.h>
  56 # else
  57 #  if HAVE_SETLOCALE
  58 #   include <locale.h>
  59 #  endif
  60 # endif
  61 #elif defined WIN32
  62 # define WIN32_LEAN_AND_MEAN
  63 # include <windows.h>
  64 #endif
  65 #if defined OS2
  66 # define INCL_DOS
  67 # include <os2.h>
  68 #endif
  69
  70 #if ENABLE_RELOCATABLE
  71 # include "relocatable.h"
  72 #else
  73 # define relocate(pathname) (pathname)
  74 #endif
  75
  76 #if defined _WIN32 || defined __WIN32__ || defined __EMX__ || defined __DJGPP__
  77   /* Win32, OS/2, DOS */
  78 # define ISSLASH(C) ((C) == '/' || (C) == '\\')
  79 #endif
  80
  81 #ifndef DIRECTORY_SEPARATOR
  82 # define DIRECTORY_SEPARATOR '/'
  83 #endif
  84
  85 #ifndef ISSLASH
  86 # define ISSLASH(C) ((C) == DIRECTORY_SEPARATOR)
  87 #endif
  88
  89 #ifdef HAVE_GETC_UNLOCKED
  90 # undef getc
  91 # define getc getc_unlocked
  92 #endif
  93
  94 /* The following static variable is declared 'volatile' to avoid a
  95    possible multithread problem in the function get_charset_aliases. If we
  96    are running in a threaded environment, and if two threads initialize
  97    'charset_aliases' simultaneously, both will produce the same value,
  98    and everything will be ok if the two assignments to 'charset_aliases'
  99    are atomic. But I don't know what will happen if the two assignments mix.  */
 100 #if __STDC__ != 1
 101 # define volatile /* empty */
 102 #endif
 103 /* Pointer to the contents of the charset.alias file, if it has already been
 104    read, else NULL.  Its format is:
 105    ALIAS_1 '\0' CANONICAL_1 '\0' ... ALIAS_n '\0' CANONICAL_n '\0' '\0'  */
 106 static const char * volatile charset_aliases;
 107
 108 /* Return a pointer to the contents of the charset.alias file.  */
 109 static const char *
 110 get_charset_aliases ()
 111 {
 112   const char *cp;
 113
 114   cp = charset_aliases;
 115   if (cp == NULL)
 116     {
 117 #if !(defined VMS || defined WIN32)
 118       FILE *fp;
 119       const char *dir = relocate (LIBDIR);
 120       const char *base = "charset.alias";
 121       char *file_name;
 122
 123       /* Concatenate dir and base into freshly allocated file_name.  */
 124       {
 125         size_t dir_len = strlen (dir);
 126         size_t base_len = strlen (base);
 127         int add_slash = (dir_len > 0 && !ISSLASH (dir[dir_len - 1]));
 128         file_name = (char *) malloc (dir_len + add_slash + base_len + 1);
 129         if (file_name != NULL)
 130           {
 131             memcpy (file_name, dir, dir_len);
 132             if (add_slash)
 133               file_name[dir_len] = DIRECTORY_SEPARATOR;
 134             memcpy (file_name + dir_len + add_slash, base, base_len + 1);
 135           }
 136       }
 137
 138       if (file_name == NULL || (fp = fopen (file_name, "r")) == NULL)
 139         /* Out of memory or file not found, treat it as empty.  */
 140         cp = "";
 141       else
 142         {
 143           /* Parse the file's contents.  */
 144           int c;
 145           char buf1[50+1];
 146           char buf2[50+1];
 147           char *res_ptr = NULL;
 148           size_t res_size = 0;
 149           size_t l1, l2;
 150
 151           for (;;)
 152             {
 153               c = getc (fp);
 154               if (c == EOF)
 155                 break;
 156               if (c == '\n' || c == ' ' || c == '\t')
 157                 continue;
 158               if (c == '#')
 159                 {
 160                   /* Skip comment, to end of line.  */
 161                   do
 162                     c = getc (fp);
 163                   while (!(c == EOF || c == '\n'));
 164                   if (c == EOF)
 165                     break;
 166                   continue;
 167                 }
 168               ungetc (c, fp);
 169               if (fscanf (fp, "%50s %50s", buf1, buf2) < 2)
 170                 break;
 171               l1 = strlen (buf1);
 172               l2 = strlen (buf2);
 173               if (res_size == 0)
 174                 {
 175                   res_size = l1 + 1 + l2 + 1;
 176                   res_ptr = (char *) malloc (res_size + 1);
 177                 }
 178               else
 179                 {
 180                   res_size += l1 + 1 + l2 + 1;
 181                   res_ptr = (char *) realloc (res_ptr, res_size + 1);
 182                 }
 183               if (res_ptr == NULL)
 184                 {
 185                   /* Out of memory. */
 186                   res_size = 0;
 187                   break;
 188                 }
 189               strcpy (res_ptr + res_size - (l2 + 1) - (l1 + 1), buf1);
 190               strcpy (res_ptr + res_size - (l2 + 1), buf2);
 191             }
 192           fclose (fp);
 193           if (res_size == 0)
 194             cp = "";
 195           else
 196             {
 197               *(res_ptr + res_size) = '\0';
 198               cp = res_ptr;
 199             }
 200         }
 201
 202       if (file_name != NULL)
 203         free (file_name);
 204
 205 #else
 206
 207 # if defined VMS
 208       /* To avoid the troubles of an extra file charset.alias_vms in the
 209          sources of many GNU packages, simply inline the aliases here.  */
 210       /* The list of encodings is taken from the OpenVMS 7.3-1 documentation
 211          "Compaq C Run-Time Library Reference Manual for OpenVMS systems"
 212          section 10.7 "Handling Different Character Sets".  */
 213       cp = "ISO8859-1" "\0" "ISO-8859-1" "\0"
 214            "ISO8859-2" "\0" "ISO-8859-2" "\0"
 215            "ISO8859-5" "\0" "ISO-8859-5" "\0"
 216            "ISO8859-7" "\0" "ISO-8859-7" "\0"
 217            "ISO8859-8" "\0" "ISO-8859-8" "\0"
 218            "ISO8859-9" "\0" "ISO-8859-9" "\0"
 219            /* Japanese */
 220            "eucJP" "\0" "EUC-JP" "\0"
 221            "SJIS" "\0" "SHIFT_JIS" "\0"
 222            "DECKANJI" "\0" "DEC-KANJI" "\0"
 223            "SDECKANJI" "\0" "EUC-JP" "\0"
 224            /* Chinese */
 225            "eucTW" "\0" "EUC-TW" "\0"
 226            "DECHANYU" "\0" "DEC-HANYU" "\0"
 227            "DECHANZI" "\0" "GB2312" "\0"
 228            /* Korean */
 229            "DECKOREAN" "\0" "EUC-KR" "\0";
 230 # endif
 231
 232 # if defined WIN32
 233       /* To avoid the troubles of installing a separate file in the same
 234          directory as the DLL and of retrieving the DLL's directory at
 235          runtime, simply inline the aliases here.  */
 236
 237       cp = "CP936" "\0" "GBK" "\0"
 238            "CP1361" "\0" "JOHAB" "\0"
 239            "CP20127" "\0" "ASCII" "\0"
 240            "CP20866" "\0" "KOI8-R" "\0"
 241            "CP21866" "\0" "KOI8-RU" "\0"
 242            "CP28591" "\0" "ISO-8859-1" "\0"
 243            "CP28592" "\0" "ISO-8859-2" "\0"
 244            "CP28593" "\0" "ISO-8859-3" "\0"
 245            "CP28594" "\0" "ISO-8859-4" "\0"
 246            "CP28595" "\0" "ISO-8859-5" "\0"
 247            "CP28596" "\0" "ISO-8859-6" "\0"
 248            "CP28597" "\0" "ISO-8859-7" "\0"
 249            "CP28598" "\0" "ISO-8859-8" "\0"
 250            "CP28599" "\0" "ISO-8859-9" "\0"
 251            "CP28605" "\0" "ISO-8859-15" "\0";
 252 # endif
 253 #endif
 254
 255       charset_aliases = cp;
 256     }
 257
 258   return cp;
 259 }
 260
 261 /* Determine the current locale's character encoding, and canonicalize it
 262    into one of the canonical names listed in config.charset.
 263    The result must not be freed; it is statically allocated.
 264    If the canonical name cannot be determined, the result is a non-canonical
 265    name.  */
 266
 267 #ifdef STATIC
 268 STATIC
 269 #endif
 270 const char *
 271 locale_charset ()
 272 {
 273   const char *codeset;
 274   const char *aliases;
 275
 276 #if !(defined WIN32 || defined OS2)
 277
 278 # if HAVE_LANGINFO_CODESET
 279
 280   /* Most systems support nl_langinfo (CODESET) nowadays.  */
 281   codeset = nl_langinfo (CODESET);
 282
 283 # else
 284
 285   /* On old systems which lack it, use setlocale or getenv.  */
 286   const char *locale = NULL;
 287
 288   /* But most old systems don't have a complete set of locales.  Some
 289      (like SunOS 4 or DJGPP) have only the C locale.  Therefore we don't
 290      use setlocale here; it would return "C" when it doesn't support the
 291      locale name the user has set.  */
 292 #  if HAVE_SETLOCALE && 0
 293   locale = setlocale (LC_CTYPE, NULL);
 294 #  endif
 295   if (locale == NULL || locale[0] == '\0')
 296     {
 297       locale = getenv ("LC_ALL");
 298       if (locale == NULL || locale[0] == '\0')
 299         {
 300           locale = getenv ("LC_CTYPE");
 301           if (locale == NULL || locale[0] == '\0')
 302             locale = getenv ("LANG");
 303         }
 304     }
 305
 306   /* On some old systems, one used to set locale = "iso8859_1". On others,
 307      you set it to "language_COUNTRY.charset". In any case, we resolve it
 308      through the charset.alias file.  */
 309   codeset = locale;
 310
 311 # endif
 312
 313 #elif defined WIN32
 314
 315   static char buf[2 + 10 + 1];
 316
 317   /* Woe32 has a function returning the locale's codepage as a number.  */
 318   sprintf (buf, "CP%u", GetACP ());
 319   codeset = buf;
 320
 321 #elif defined OS2
 322
 323   const char *locale;
 324   static char buf[2 + 10 + 1];
 325   ULONG cp[3];
 326   ULONG cplen;
 327
 328   /* Allow user to override the codeset, as set in the operating system,
 329      with standard language environment variables.  */
 330   locale = getenv ("LC_ALL");
 331   if (locale == NULL || locale[0] == '\0')
 332     {
 333       locale = getenv ("LC_CTYPE");
 334       if (locale == NULL || locale[0] == '\0')
 335         locale = getenv ("LANG");
 336     }
 337   if (locale != NULL && locale[0] != '\0')
 338     {
 339       /* If the locale name contains an encoding after the dot, return it.  */
 340       const char *dot = strchr (locale, '.');
 341
 342       if (dot != NULL)
 343         {
 344           const char *modifier;
 345
 346           dot++;
 347           /* Look for the possible @... trailer and remove it, if any.  */
 348           modifier = strchr (dot, '@');
 349           if (modifier == NULL)
 350             return dot;
 351           if (modifier - dot < sizeof (buf))
 352             {
 353               memcpy (buf, dot, modifier - dot);
 354               buf [modifier - dot] = '\0';
 355               return buf;
 356             }
 357         }
 358
 359       /* Resolve through the charset.alias file.  */
 360       codeset = locale;
 361     }
 362   else
 363     {
 364       /* OS/2 has a function returning the locale's codepage as a number.  */
 365       if (DosQueryCp (sizeof (cp), cp, &cplen))
 366         codeset = "";
 367       else
 368         {
 369           sprintf (buf, "CP%u", cp[0]);
 370           codeset = buf;
 371         }
 372     }
 373
 374 #endif
 375
 376   if (codeset == NULL)
 377     /* The canonical name cannot be determined.  */
 378     codeset = "";
 379
 380   /* Resolve alias. */
 381   for (aliases = get_charset_aliases ();
 382        *aliases != '\0';
 383        aliases += strlen (aliases) + 1, aliases += strlen (aliases) + 1)
 384     if (strcmp (codeset, aliases) == 0
 385         || (aliases[0] == '*' && aliases[1] == '\0'))
 386       {
 387         codeset = aliases + strlen (aliases) + 1;
 388         break;
 389       }
 390
 391   /* Don't return an empty string.  GNU libc and GNU libiconv interpret
 392      the empty string as denoting "the locale's character encoding",
 393      thus GNU libiconv would call this function a second time.  */
 394   if (codeset[0] == '\0')
 395     codeset = "ASCII";
 396
 397   return codeset;
 398 }