gnu/dist/texinfo/intl/localcharset.c

   1 /*      $NetBSD$        */
   2
   3 /* Determine a canonical name for the current locale's character encoding.
   4
   5    Copyright (C) 2000-2003 Free Software Foundation, Inc.
   6
   7    This program is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU Library General Public License as published
   9    by the Free Software Foundation; either version 2, or (at your option)
  10    any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Library General Public License for more details.
  16
  17    You should have received a copy of the GNU Library General Public
  18    License along with this program; if not, write to the Free Software
  19    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  20    USA.  */
  21
  22 /* Written by Bruno Haible <bruno@clisp.org>.  */
  23
  24 #ifdef HAVE_CONFIG_H
  25 # include <config.h>
  26 #endif
  27
  28 /* Specification.  */
  29 #include "localcharset.h"
  30
  31 #if HAVE_STDDEF_H
  32 # include <stddef.h>
  33 #endif
  34
  35 #include <stdio.h>
  36 #if HAVE_STRING_H
  37 # include <string.h>
  38 #else
  39 # include <strings.h>
  40 #endif
  41 #if HAVE_STDLIB_H
  42 # include <stdlib.h>
  43 #endif
  44
  45 #if defined _WIN32 || defined __WIN32__
  46 # undef WIN32   /* avoid warning on mingw32 */
  47 # define WIN32
  48 #endif
  49
  50 #if defined __EMX__
  51 /* Assume EMX program runs on OS/2, even if compiled under DOS.  */
  52 # define OS2
  53 #endif
  54
  55 #if !defined WIN32
  56 # if HAVE_LANGINFO_CODESET
  57 #  include <langinfo.h>
  58 # else
  59 #  if HAVE_SETLOCALE
  60 #   include <locale.h>
  61 #  endif
  62 # endif
  63 #elif defined WIN32
  64 # define WIN32_LEAN_AND_MEAN
  65 # include <windows.h>
  66 #endif
  67 #if defined OS2
  68 # define INCL_DOS
  69 # include <os2.h>
  70 #endif
  71
  72 #if ENABLE_RELOCATABLE
  73 # include "relocatable.h"
  74 #else
  75 # define relocate(pathname) (pathname)
  76 #endif
  77
  78 #if defined _WIN32 || defined __WIN32__ || defined __EMX__ || defined __DJGPP__
  79   /* Win32, OS/2, DOS */
  80 # define ISSLASH(C) ((C) == '/' || (C) == '\\')
  81 #endif
  82
  83 #ifndef DIRECTORY_SEPARATOR
  84 # define DIRECTORY_SEPARATOR '/'
  85 #endif
  86
  87 #ifndef ISSLASH
  88 # define ISSLASH(C) ((C) == DIRECTORY_SEPARATOR)
  89 #endif
  90
  91 #if HAVE_DECL_GETC_UNLOCKED
  92 # undef getc
  93 # define getc getc_unlocked
  94 #endif
  95
  96 /* The following static variable is declared 'volatile' to avoid a
  97    possible multithread problem in the function get_charset_aliases. If we
  98    are running in a threaded environment, and if two threads initialize
  99    'charset_aliases' simultaneously, both will produce the same value,
 100    and everything will be ok if the two assignments to 'charset_aliases'
 101    are atomic. But I don't know what will happen if the two assignments mix.  */
 102 #if __STDC__ != 1
 103 # define volatile /* empty */
 104 #endif
 105 /* Pointer to the contents of the charset.alias file, if it has already been
 106    read, else NULL.  Its format is:
 107    ALIAS_1 '\0' CANONICAL_1 '\0' ... ALIAS_n '\0' CANONICAL_n '\0' '\0'  */
 108 static const char * volatile charset_aliases;
 109
 110 /* Return a pointer to the contents of the charset.alias file.  */
 111 static const char *
 112 get_charset_aliases ()
 113 {
 114   const char *cp;
 115
 116   cp = charset_aliases;
 117   if (cp == NULL)
 118     {
 119 #if !(defined VMS || defined WIN32)
 120       FILE *fp;
 121       const char *dir = relocate (LIBDIR);
 122       const char *base = "charset.alias";
 123       char *file_name;
 124
 125       /* Concatenate dir and base into freshly allocated file_name.  */
 126       {
 127         size_t dir_len = strlen (dir);
 128         size_t base_len = strlen (base);
 129         int add_slash = (dir_len > 0 && !ISSLASH (dir[dir_len - 1]));
 130         file_name = (char *) malloc (dir_len + add_slash + base_len + 1);
 131         if (file_name != NULL)
 132           {
 133             memcpy (file_name, dir, dir_len);
 134             if (add_slash)
 135               file_name[dir_len] = DIRECTORY_SEPARATOR;
 136             memcpy (file_name + dir_len + add_slash, base, base_len + 1);
 137           }
 138       }
 139
 140       if (file_name == NULL || (fp = fopen (file_name, "r")) == NULL)
 141         /* Out of memory or file not found, treat it as empty.  */
 142         cp = "";
 143       else
 144         {
 145           /* Parse the file's contents.  */
 146           int c;
 147           char buf1[50+1];
 148           char buf2[50+1];
 149           char *res_ptr = NULL;
 150           size_t res_size = 0;
 151           size_t l1, l2;
 152
 153           for (;;)
 154             {
 155               c = getc (fp);
 156               if (c == EOF)
 157                 break;
 158               if (c == '\n' || c == ' ' || c == '\t')
 159                 continue;
 160               if (c == '#')
 161                 {
 162                   /* Skip comment, to end of line.  */
 163                   do
 164                     c = getc (fp);
 165                   while (!(c == EOF || c == '\n'));
 166                   if (c == EOF)
 167                     break;
 168                   continue;
 169                 }
 170               ungetc (c, fp);
 171               if (fscanf (fp, "%50s %50s", buf1, buf2) < 2)
 172                 break;
 173               l1 = strlen (buf1);
 174               l2 = strlen (buf2);
 175               if (res_size == 0)
 176                 {
 177                   res_size = l1 + 1 + l2 + 1;
 178                   res_ptr = (char *) malloc (res_size + 1);
 179                 }
 180               else
 181                 {
 182                   res_size += l1 + 1 + l2 + 1;
 183                   res_ptr = (char *) realloc (res_ptr, res_size + 1);
 184                 }
 185               if (res_ptr == NULL)
 186                 {
 187                   /* Out of memory. */
 188                   res_size = 0;
 189                   break;
 190                 }
 191               strcpy (res_ptr + res_size - (l2 + 1) - (l1 + 1), buf1);
 192               strcpy (res_ptr + res_size - (l2 + 1), buf2);
 193             }
 194           fclose (fp);
 195           if (res_size == 0)
 196             cp = "";
 197           else
 198             {
 199               *(res_ptr + res_size) = '\0';
 200               cp = res_ptr;
 201             }
 202         }
 203
 204       if (file_name != NULL)
 205         free (file_name);
 206
 207 #else
 208
 209 # if defined VMS
 210       /* To avoid the troubles of an extra file charset.alias_vms in the
 211          sources of many GNU packages, simply inline the aliases here.  */
 212       /* The list of encodings is taken from the OpenVMS 7.3-1 documentation
 213          "Compaq C Run-Time Library Reference Manual for OpenVMS systems"
 214          section 10.7 "Handling Different Character Sets".  */
 215       cp = "ISO8859-1" "\0" "ISO-8859-1" "\0"
 216            "ISO8859-2" "\0" "ISO-8859-2" "\0"
 217            "ISO8859-5" "\0" "ISO-8859-5" "\0"
 218            "ISO8859-7" "\0" "ISO-8859-7" "\0"
 219            "ISO8859-8" "\0" "ISO-8859-8" "\0"
 220            "ISO8859-9" "\0" "ISO-8859-9" "\0"
 221            /* Japanese */
 222            "eucJP" "\0" "EUC-JP" "\0"
 223            "SJIS" "\0" "SHIFT_JIS" "\0"
 224            "DECKANJI" "\0" "DEC-KANJI" "\0"
 225            "SDECKANJI" "\0" "EUC-JP" "\0"
 226            /* Chinese */
 227            "eucTW" "\0" "EUC-TW" "\0"
 228            "DECHANYU" "\0" "DEC-HANYU" "\0"
 229            "DECHANZI" "\0" "GB2312" "\0"
 230            /* Korean */
 231            "DECKOREAN" "\0" "EUC-KR" "\0";
 232 # endif
 233
 234 # if defined WIN32
 235       /* To avoid the troubles of installing a separate file in the same
 236          directory as the DLL and of retrieving the DLL's directory at
 237          runtime, simply inline the aliases here.  */
 238
 239       cp = "CP936" "\0" "GBK" "\0"
 240            "CP1361" "\0" "JOHAB" "\0"
 241            "CP20127" "\0" "ASCII" "\0"
 242            "CP20866" "\0" "KOI8-R" "\0"
 243            "CP21866" "\0" "KOI8-RU" "\0"
 244            "CP28591" "\0" "ISO-8859-1" "\0"
 245            "CP28592" "\0" "ISO-8859-2" "\0"
 246            "CP28593" "\0" "ISO-8859-3" "\0"
 247            "CP28594" "\0" "ISO-8859-4" "\0"
 248            "CP28595" "\0" "ISO-8859-5" "\0"
 249            "CP28596" "\0" "ISO-8859-6" "\0"
 250            "CP28597" "\0" "ISO-8859-7" "\0"
 251            "CP28598" "\0" "ISO-8859-8" "\0"
 252            "CP28599" "\0" "ISO-8859-9" "\0"
 253            "CP28605" "\0" "ISO-8859-15" "\0";
 254 # endif
 255 #endif
 256
 257       charset_aliases = cp;
 258     }
 259
 260   return cp;
 261 }
 262
 263 /* Determine the current locale's character encoding, and canonicalize it
 264    into one of the canonical names listed in config.charset.
 265    The result must not be freed; it is statically allocated.
 266    If the canonical name cannot be determined, the result is a non-canonical
 267    name.  */
 268
 269 #ifdef STATIC
 270 STATIC
 271 #endif
 272 const char *
 273 locale_charset ()
 274 {
 275   const char *codeset;
 276   const char *aliases;
 277
 278 #if !(defined WIN32 || defined OS2)
 279
 280 # if HAVE_LANGINFO_CODESET
 281
 282   /* Most systems support nl_langinfo (CODESET) nowadays.  */
 283   codeset = nl_langinfo (CODESET);
 284
 285 # else
 286
 287   /* On old systems which lack it, use setlocale or getenv.  */
 288   const char *locale = NULL;
 289
 290   /* But most old systems don't have a complete set of locales.  Some
 291      (like SunOS 4 or DJGPP) have only the C locale.  Therefore we don't
 292      use setlocale here; it would return "C" when it doesn't support the
 293      locale name the user has set.  */
 294 #  if HAVE_SETLOCALE && 0
 295   locale = setlocale (LC_CTYPE, NULL);
 296 #  endif
 297   if (locale == NULL || locale[0] == '\0')
 298     {
 299       locale = getenv ("LC_ALL");
 300       if (locale == NULL || locale[0] == '\0')
 301         {
 302           locale = getenv ("LC_CTYPE");
 303           if (locale == NULL || locale[0] == '\0')
 304             locale = getenv ("LANG");
 305         }
 306     }
 307
 308   /* On some old systems, one used to set locale = "iso8859_1". On others,
 309      you set it to "language_COUNTRY.charset". In any case, we resolve it
 310      through the charset.alias file.  */
 311   codeset = locale;
 312
 313 # endif
 314
 315 #elif defined WIN32
 316
 317   static char buf[2 + 10 + 1];
 318
 319   /* Woe32 has a function returning the locale's codepage as a number.  */
 320   sprintf (buf, "CP%u", GetACP ());
 321   codeset = buf;
 322
 323 #elif defined OS2
 324
 325   const char *locale;
 326   static char buf[2 + 10 + 1];
 327   ULONG cp[3];
 328   ULONG cplen;
 329
 330   /* Allow user to override the codeset, as set in the operating system,
 331      with standard language environment variables.  */
 332   locale = getenv ("LC_ALL");
 333   if (locale == NULL || locale[0] == '\0')
 334     {
 335       locale = getenv ("LC_CTYPE");
 336       if (locale == NULL || locale[0] == '\0')
 337         locale = getenv ("LANG");
 338     }
 339   if (locale != NULL && locale[0] != '\0')
 340     {
 341       /* If the locale name contains an encoding after the dot, return it.  */
 342       const char *dot = strchr (locale, '.');
 343
 344       if (dot != NULL)
 345         {
 346           const char *modifier;
 347
 348           dot++;
 349           /* Look for the possible @... trailer and remove it, if any.  */
 350           modifier = strchr (dot, '@');
 351           if (modifier == NULL)
 352             return dot;
 353           if (modifier - dot < sizeof (buf))
 354             {
 355               memcpy (buf, dot, modifier - dot);
 356               buf [modifier - dot] = '\0';
 357               return buf;
 358             }
 359         }
 360
 361       /* Resolve through the charset.alias file.  */
 362       codeset = locale;
 363     }
 364   else
 365     {
 366       /* OS/2 has a function returning the locale's codepage as a number.  */
 367       if (DosQueryCp (sizeof (cp), cp, &cplen))
 368         codeset = "";
 369       else
 370         {
 371           sprintf (buf, "CP%u", cp[0]);
 372           codeset = buf;
 373         }
 374     }
 375
 376 #endif
 377
 378   if (codeset == NULL)
 379     /* The canonical name cannot be determined.  */
 380     codeset = "";
 381
 382   /* Resolve alias. */
 383   for (aliases = get_charset_aliases ();
 384        *aliases != '\0';
 385        aliases += strlen (aliases) + 1, aliases += strlen (aliases) + 1)
 386     if (strcmp (codeset, aliases) == 0
 387         || (aliases[0] == '*' && aliases[1] == '\0'))
 388       {
 389         codeset = aliases + strlen (aliases) + 1;
 390         break;
 391       }
 392
 393   /* Don't return an empty string.  GNU libc and GNU libiconv interpret
 394      the empty string as denoting "the locale's character encoding",
 395      thus GNU libiconv would call this function a second time.  */
 396   if (codeset[0] == '\0')
 397     codeset = "ASCII";
 398
 399   return codeset;
 400 }