lib/localcharset.c

   1 /* Determine a canonical name for the current locale's character encoding.
   2
   3    Copyright (C) 2000-2006, 2008 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as published by
   7    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
  13    GNU Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License along
  16    with this program; if not, write to the Free Software Foundation,
  17    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  18
  19 /* Written by Bruno Haible <bruno@clisp.org>.  */
  20
  21 #include <config.h>
  22
  23 /* Specification.  */
  24 #include "localcharset.h"
  25
  26 #include <stddef.h>
  27 #include <stdio.h>
  28 #include <string.h>
  29 #include <stdlib.h>
  30
  31 #if defined _WIN32 || defined __WIN32__
  32 # define WIN32_NATIVE
  33 #endif
  34
  35 #if defined __EMX__
  36 /* Assume EMX program runs on OS/2, even if compiled under DOS.  */
  37 # ifndef OS2
  38 #  define OS2
  39 # endif
  40 #endif
  41
  42 #if !defined WIN32_NATIVE
  43 # if HAVE_LANGINFO_CODESET
  44 #  include <langinfo.h>
  45 # else
  46 #  if 0 /* see comment below */
  47 #   include <locale.h>
  48 #  endif
  49 # endif
  50 # ifdef __CYGWIN__
  51 #  define WIN32_LEAN_AND_MEAN
  52 #  include <windows.h>
  53 # endif
  54 #elif defined WIN32_NATIVE
  55 # define WIN32_LEAN_AND_MEAN
  56 # include <windows.h>
  57 #endif
  58 #if defined OS2
  59 # define INCL_DOS
  60 # include <os2.h>
  61 #endif
  62
  63 #if ENABLE_RELOCATABLE
  64 # include "relocatable.h"
  65 #else
  66 # define relocate(pathname) (pathname)
  67 #endif
  68
  69 /* Get LIBDIR.  */
  70 #ifndef LIBDIR
  71 # include "configmake.h"
  72 #endif
  73
  74 #if defined _WIN32 || defined __WIN32__ || defined __CYGWIN__ || defined __EMX__ || defined __DJGPP__
  75   /* Win32, Cygwin, OS/2, DOS */
  76 # define ISSLASH(C) ((C) == '/' || (C) == '\\')
  77 #endif
  78
  79 #ifndef DIRECTORY_SEPARATOR
  80 # define DIRECTORY_SEPARATOR '/'
  81 #endif
  82
  83 #ifndef ISSLASH
  84 # define ISSLASH(C) ((C) == DIRECTORY_SEPARATOR)
  85 #endif
  86
  87 #if HAVE_DECL_GETC_UNLOCKED
  88 # undef getc
  89 # define getc getc_unlocked
  90 #endif
  91
  92 /* The following static variable is declared 'volatile' to avoid a
  93    possible multithread problem in the function get_charset_aliases. If we
  94    are running in a threaded environment, and if two threads initialize
  95    'charset_aliases' simultaneously, both will produce the same value,
  96    and everything will be ok if the two assignments to 'charset_aliases'
  97    are atomic. But I don't know what will happen if the two assignments mix.  */
  98 #if __STDC__ != 1
  99 # define volatile /* empty */
 100 #endif
 101 /* Pointer to the contents of the charset.alias file, if it has already been
 102    read, else NULL.  Its format is:
 103    ALIAS_1 '\0' CANONICAL_1 '\0' ... ALIAS_n '\0' CANONICAL_n '\0' '\0'  */
 104 static const char * volatile charset_aliases;
 105
 106 /* Return a pointer to the contents of the charset.alias file.  */
 107 static const char *
 108 get_charset_aliases (void)
 109 {
 110   const char *cp;
 111
 112   cp = charset_aliases;
 113   if (cp == NULL)
 114     {
 115 #if !(defined VMS || defined WIN32_NATIVE || defined __CYGWIN__)
 116       FILE *fp;
 117       const char *dir;
 118       const char *base = "charset.alias";
 119       char *file_name;
 120
 121       /* Make it possible to override the charset.alias location.  This is
 122          necessary for running the testsuite before "make install".  */
 123       dir = getenv ("CHARSETALIASDIR");
 124       if (dir == NULL || dir[0] == '\0')
 125         dir = relocate (LIBDIR);
 126
 127       /* Concatenate dir and base into freshly allocated file_name.  */
 128       {
 129         size_t dir_len = strlen (dir);
 130         size_t base_len = strlen (base);
 131         int add_slash = (dir_len > 0 && !ISSLASH (dir[dir_len - 1]));
 132         file_name = (char *) malloc (dir_len + add_slash + base_len + 1);
 133         if (file_name != NULL)
 134           {
 135             memcpy (file_name, dir, dir_len);
 136             if (add_slash)
 137               file_name[dir_len] = DIRECTORY_SEPARATOR;
 138             memcpy (file_name + dir_len + add_slash, base, base_len + 1);
 139           }
 140       }
 141
 142       if (file_name == NULL || (fp = fopen (file_name, "r")) == NULL)
 143         /* Out of memory or file not found, treat it as empty.  */
 144         cp = "";
 145       else
 146         {
 147           /* Parse the file's contents.  */
 148           char *res_ptr = NULL;
 149           size_t res_size = 0;
 150
 151           for (;;)
 152             {
 153               int c;
 154               char buf1[50+1];
 155               char buf2[50+1];
 156               size_t l1, l2;
 157               char *old_res_ptr;
 158
 159               c = getc (fp);
 160               if (c == EOF)
 161                 break;
 162               if (c == '\n' || c == ' ' || c == '\t')
 163                 continue;
 164               if (c == '#')
 165                 {
 166                   /* Skip comment, to end of line.  */
 167                   do
 168                     c = getc (fp);
 169                   while (!(c == EOF || c == '\n'));
 170                   if (c == EOF)
 171                     break;
 172                   continue;
 173                 }
 174               ungetc (c, fp);
 175               if (fscanf (fp, "%50s %50s", buf1, buf2) < 2)
 176                 break;
 177               l1 = strlen (buf1);
 178               l2 = strlen (buf2);
 179               old_res_ptr = res_ptr;
 180               if (res_size == 0)
 181                 {
 182                   res_size = l1 + 1 + l2 + 1;
 183                   res_ptr = (char *) malloc (res_size + 1);
 184                 }
 185               else
 186                 {
 187                   res_size += l1 + 1 + l2 + 1;
 188                   res_ptr = (char *) realloc (res_ptr, res_size + 1);
 189                 }
 190               if (res_ptr == NULL)
 191                 {
 192                   /* Out of memory. */
 193                   res_size = 0;
 194                   if (old_res_ptr != NULL)
 195                     free (old_res_ptr);
 196                   break;
 197                 }
 198               strcpy (res_ptr + res_size - (l2 + 1) - (l1 + 1), buf1);
 199               strcpy (res_ptr + res_size - (l2 + 1), buf2);
 200             }
 201           fclose (fp);
 202           if (res_size == 0)
 203             cp = "";
 204           else
 205             {
 206               *(res_ptr + res_size) = '\0';
 207               cp = res_ptr;
 208             }
 209         }
 210
 211       if (file_name != NULL)
 212         free (file_name);
 213
 214 #else
 215
 216 # if defined VMS
 217       /* To avoid the troubles of an extra file charset.alias_vms in the
 218          sources of many GNU packages, simply inline the aliases here.  */
 219       /* The list of encodings is taken from the OpenVMS 7.3-1 documentation
 220          "Compaq C Run-Time Library Reference Manual for OpenVMS systems"
 221          section 10.7 "Handling Different Character Sets".  */
 222       cp = "ISO8859-1" "\0" "ISO-8859-1" "\0"
 223            "ISO8859-2" "\0" "ISO-8859-2" "\0"
 224            "ISO8859-5" "\0" "ISO-8859-5" "\0"
 225            "ISO8859-7" "\0" "ISO-8859-7" "\0"
 226            "ISO8859-8" "\0" "ISO-8859-8" "\0"
 227            "ISO8859-9" "\0" "ISO-8859-9" "\0"
 228            /* Japanese */
 229            "eucJP" "\0" "EUC-JP" "\0"
 230            "SJIS" "\0" "SHIFT_JIS" "\0"
 231            "DECKANJI" "\0" "DEC-KANJI" "\0"
 232            "SDECKANJI" "\0" "EUC-JP" "\0"
 233            /* Chinese */
 234            "eucTW" "\0" "EUC-TW" "\0"
 235            "DECHANYU" "\0" "DEC-HANYU" "\0"
 236            "DECHANZI" "\0" "GB2312" "\0"
 237            /* Korean */
 238            "DECKOREAN" "\0" "EUC-KR" "\0";
 239 # endif
 240
 241 # if defined WIN32_NATIVE || defined __CYGWIN__
 242       /* To avoid the troubles of installing a separate file in the same
 243          directory as the DLL and of retrieving the DLL's directory at
 244          runtime, simply inline the aliases here.  */
 245
 246       cp = "CP936" "\0" "GBK" "\0"
 247            "CP1361" "\0" "JOHAB" "\0"
 248            "CP20127" "\0" "ASCII" "\0"
 249            "CP20866" "\0" "KOI8-R" "\0"
 250            "CP20936" "\0" "GB2312" "\0"
 251            "CP21866" "\0" "KOI8-RU" "\0"
 252            "CP28591" "\0" "ISO-8859-1" "\0"
 253            "CP28592" "\0" "ISO-8859-2" "\0"
 254            "CP28593" "\0" "ISO-8859-3" "\0"
 255            "CP28594" "\0" "ISO-8859-4" "\0"
 256            "CP28595" "\0" "ISO-8859-5" "\0"
 257            "CP28596" "\0" "ISO-8859-6" "\0"
 258            "CP28597" "\0" "ISO-8859-7" "\0"
 259            "CP28598" "\0" "ISO-8859-8" "\0"
 260            "CP28599" "\0" "ISO-8859-9" "\0"
 261            "CP28605" "\0" "ISO-8859-15" "\0"
 262            "CP38598" "\0" "ISO-8859-8" "\0"
 263            "CP51932" "\0" "EUC-JP" "\0"
 264            "CP51936" "\0" "GB2312" "\0"
 265            "CP51949" "\0" "EUC-KR" "\0"
 266            "CP51950" "\0" "EUC-TW" "\0"
 267            "CP54936" "\0" "GB18030" "\0"
 268            "CP65001" "\0" "UTF-8" "\0";
 269 # endif
 270 #endif
 271
 272       charset_aliases = cp;
 273     }
 274
 275   return cp;
 276 }
 277
 278 /* Determine the current locale's character encoding, and canonicalize it
 279    into one of the canonical names listed in config.charset.
 280    The result must not be freed; it is statically allocated.
 281    If the canonical name cannot be determined, the result is a non-canonical
 282    name.  */
 283
 284 #ifdef STATIC
 285 STATIC
 286 #endif
 287 const char *
 288 locale_charset (void)
 289 {
 290   const char *codeset;
 291   const char *aliases;
 292
 293 #if !(defined WIN32_NATIVE || defined OS2)
 294
 295 # if HAVE_LANGINFO_CODESET
 296
 297   /* Most systems support nl_langinfo (CODESET) nowadays.  */
 298   codeset = nl_langinfo (CODESET);
 299
 300 #  ifdef __CYGWIN__
 301   /* Cygwin 2006 does not have locales.  nl_langinfo (CODESET) always
 302      returns "US-ASCII".  As long as this is not fixed, return the suffix
 303      of the locale name from the environment variables (if present) or
 304      the codepage as a number.  */
 305   if (codeset != NULL && strcmp (codeset, "US-ASCII") == 0)
 306     {
 307       const char *locale;
 308       static char buf[2 + 10 + 1];
 309
 310       locale = getenv ("LC_ALL");
 311       if (locale == NULL || locale[0] == '\0')
 312         {
 313           locale = getenv ("LC_CTYPE");
 314           if (locale == NULL || locale[0] == '\0')
 315             locale = getenv ("LANG");
 316         }
 317       if (locale != NULL && locale[0] != '\0')
 318         {
 319           /* If the locale name contains an encoding after the dot, return
 320              it.  */
 321           const char *dot = strchr (locale, '.');
 322
 323           if (dot != NULL)
 324             {
 325               const char *modifier;
 326
 327               dot++;
 328               /* Look for the possible @... trailer and remove it, if any.  */
 329               modifier = strchr (dot, '@');
 330               if (modifier == NULL)
 331                 return dot;
 332               if (modifier - dot < sizeof (buf))
 333                 {
 334                   memcpy (buf, dot, modifier - dot);
 335                   buf [modifier - dot] = '\0';
 336                   return buf;
 337                 }
 338             }
 339         }
 340
 341       /* Woe32 has a function returning the locale's codepage as a number.  */
 342       sprintf (buf, "CP%u", GetACP ());
 343       codeset = buf;
 344     }
 345 #  endif
 346
 347 # else
 348
 349   /* On old systems which lack it, use setlocale or getenv.  */
 350   const char *locale = NULL;
 351
 352   /* But most old systems don't have a complete set of locales.  Some
 353      (like SunOS 4 or DJGPP) have only the C locale.  Therefore we don't
 354      use setlocale here; it would return "C" when it doesn't support the
 355      locale name the user has set.  */
 356 #  if 0
 357   locale = setlocale (LC_CTYPE, NULL);
 358 #  endif
 359   if (locale == NULL || locale[0] == '\0')
 360     {
 361       locale = getenv ("LC_ALL");
 362       if (locale == NULL || locale[0] == '\0')
 363         {
 364           locale = getenv ("LC_CTYPE");
 365           if (locale == NULL || locale[0] == '\0')
 366             locale = getenv ("LANG");
 367         }
 368     }
 369
 370   /* On some old systems, one used to set locale = "iso8859_1". On others,
 371      you set it to "language_COUNTRY.charset". In any case, we resolve it
 372      through the charset.alias file.  */
 373   codeset = locale;
 374
 375 # endif
 376
 377 #elif defined WIN32_NATIVE
 378
 379   static char buf[2 + 10 + 1];
 380
 381   /* Woe32 has a function returning the locale's codepage as a number.  */
 382   sprintf (buf, "CP%u", GetACP ());
 383   codeset = buf;
 384
 385 #elif defined OS2
 386
 387   const char *locale;
 388   static char buf[2 + 10 + 1];
 389   ULONG cp[3];
 390   ULONG cplen;
 391
 392   /* Allow user to override the codeset, as set in the operating system,
 393      with standard language environment variables.  */
 394   locale = getenv ("LC_ALL");
 395   if (locale == NULL || locale[0] == '\0')
 396     {
 397       locale = getenv ("LC_CTYPE");
 398       if (locale == NULL || locale[0] == '\0')
 399         locale = getenv ("LANG");
 400     }
 401   if (locale != NULL && locale[0] != '\0')
 402     {
 403       /* If the locale name contains an encoding after the dot, return it.  */
 404       const char *dot = strchr (locale, '.');
 405
 406       if (dot != NULL)
 407         {
 408           const char *modifier;
 409
 410           dot++;
 411           /* Look for the possible @... trailer and remove it, if any.  */
 412           modifier = strchr (dot, '@');
 413           if (modifier == NULL)
 414             return dot;
 415           if (modifier - dot < sizeof (buf))
 416             {
 417               memcpy (buf, dot, modifier - dot);
 418               buf [modifier - dot] = '\0';
 419               return buf;
 420             }
 421         }
 422
 423       /* Resolve through the charset.alias file.  */
 424       codeset = locale;
 425     }
 426   else
 427     {
 428       /* OS/2 has a function returning the locale's codepage as a number.  */
 429       if (DosQueryCp (sizeof (cp), cp, &cplen))
 430         codeset = "";
 431       else
 432         {
 433           sprintf (buf, "CP%u", cp[0]);
 434           codeset = buf;
 435         }
 436     }
 437
 438 #endif
 439
 440   if (codeset == NULL)
 441     /* The canonical name cannot be determined.  */
 442     codeset = "";
 443
 444   /* Resolve alias. */
 445   for (aliases = get_charset_aliases ();
 446        *aliases != '\0';
 447        aliases += strlen (aliases) + 1, aliases += strlen (aliases) + 1)
 448     if (strcmp (codeset, aliases) == 0
 449         || (aliases[0] == '*' && aliases[1] == '\0'))
 450       {
 451         codeset = aliases + strlen (aliases) + 1;
 452         break;
 453       }
 454
 455   /* Don't return an empty string.  GNU libc and GNU libiconv interpret
 456      the empty string as denoting "the locale's character encoding",
 457      thus GNU libiconv would call this function a second time.  */
 458   if (codeset[0] == '\0')
 459     codeset = "ASCII";
 460
 461   return codeset;
 462 }