gl/localcharset.c

   1 /* Determine a canonical name for the current locale's character encoding.
   2
   3    Copyright (C) 2000-2006, 2008-2013 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 General Public License as published by
   7    the Free Software Foundation; either version 3, 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 General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License along
  16    with this program; if not, see <http://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Bruno Haible <bruno@clisp.org>.  */
  19
  20 #include <config.h>
  21
  22 /* Specification.  */
  23 #include "localcharset.h"
  24
  25 #include <fcntl.h>
  26 #include <stddef.h>
  27 #include <stdio.h>
  28 #include <string.h>
  29 #include <stdlib.h>
  30
  31 #if defined __APPLE__ && defined __MACH__ && HAVE_LANGINFO_CODESET
  32 # define DARWIN7 /* Darwin 7 or newer, i.e. Mac OS X 10.3 or newer */
  33 #endif
  34
  35 #if defined _WIN32 || defined __WIN32__
  36 # define WINDOWS_NATIVE
  37 #endif
  38
  39 #if defined __EMX__
  40 /* Assume EMX program runs on OS/2, even if compiled under DOS.  */
  41 # ifndef OS2
  42 #  define OS2
  43 # endif
  44 #endif
  45
  46 #if !defined WINDOWS_NATIVE
  47 # include <unistd.h>
  48 # if HAVE_LANGINFO_CODESET
  49 #  include <langinfo.h>
  50 # else
  51 #  if 0 /* see comment below */
  52 #   include <locale.h>
  53 #  endif
  54 # endif
  55 # ifdef __CYGWIN__
  56 #  define WIN32_LEAN_AND_MEAN
  57 #  include <windows.h>
  58 # endif
  59 #elif defined WINDOWS_NATIVE
  60 # define WIN32_LEAN_AND_MEAN
  61 # include <windows.h>
  62 #endif
  63 #if defined OS2
  64 # define INCL_DOS
  65 # include <os2.h>
  66 #endif
  67
  68 /* For MB_CUR_MAX_L */
  69 #if defined DARWIN7
  70 # include <xlocale.h>
  71 #endif
  72
  73 #if ENABLE_RELOCATABLE
  74 # include "relocatable.h"
  75 #else
  76 # define relocate(pathname) (pathname)
  77 #endif
  78
  79 /* Get LIBDIR.  */
  80 #ifndef LIBDIR
  81 # include "configmake.h"
  82 #endif
  83
  84 /* Define O_NOFOLLOW to 0 on platforms where it does not exist.  */
  85 #ifndef O_NOFOLLOW
  86 # define O_NOFOLLOW 0
  87 #endif
  88
  89 #if defined _WIN32 || defined __WIN32__ || defined __CYGWIN__ || defined __EMX__ || defined __DJGPP__
  90   /* Native Windows, Cygwin, OS/2, DOS */
  91 # define ISSLASH(C) ((C) == '/' || (C) == '\\')
  92 #endif
  93
  94 #ifndef DIRECTORY_SEPARATOR
  95 # define DIRECTORY_SEPARATOR '/'
  96 #endif
  97
  98 #ifndef ISSLASH
  99 # define ISSLASH(C) ((C) == DIRECTORY_SEPARATOR)
 100 #endif
 101
 102 #if HAVE_DECL_GETC_UNLOCKED
 103 # undef getc
 104 # define getc getc_unlocked
 105 #endif
 106
 107 /* The following static variable is declared 'volatile' to avoid a
 108    possible multithread problem in the function get_charset_aliases. If we
 109    are running in a threaded environment, and if two threads initialize
 110    'charset_aliases' simultaneously, both will produce the same value,
 111    and everything will be ok if the two assignments to 'charset_aliases'
 112    are atomic. But I don't know what will happen if the two assignments mix.  */
 113 #if __STDC__ != 1
 114 # define volatile /* empty */
 115 #endif
 116 /* Pointer to the contents of the charset.alias file, if it has already been
 117    read, else NULL.  Its format is:
 118    ALIAS_1 '\0' CANONICAL_1 '\0' ... ALIAS_n '\0' CANONICAL_n '\0' '\0'  */
 119 static const char * volatile charset_aliases;
 120
 121 /* Return a pointer to the contents of the charset.alias file.  */
 122 static const char *
 123 get_charset_aliases (void)
 124 {
 125   const char *cp;
 126
 127   cp = charset_aliases;
 128   if (cp == NULL)
 129     {
 130 #if !(defined DARWIN7 || defined VMS || defined WINDOWS_NATIVE || defined __CYGWIN__)
 131       const char *dir;
 132       const char *base = "charset.alias";
 133       char *file_name;
 134
 135       /* Make it possible to override the charset.alias location.  This is
 136          necessary for running the testsuite before "make install".  */
 137       dir = getenv ("CHARSETALIASDIR");
 138       if (dir == NULL || dir[0] == '\0')
 139         dir = relocate (LIBDIR);
 140
 141       /* Concatenate dir and base into freshly allocated file_name.  */
 142       {
 143         size_t dir_len = strlen (dir);
 144         size_t base_len = strlen (base);
 145         int add_slash = (dir_len > 0 && !ISSLASH (dir[dir_len - 1]));
 146         file_name = (char *) malloc (dir_len + add_slash + base_len + 1);
 147         if (file_name != NULL)
 148           {
 149             memcpy (file_name, dir, dir_len);
 150             if (add_slash)
 151               file_name[dir_len] = DIRECTORY_SEPARATOR;
 152             memcpy (file_name + dir_len + add_slash, base, base_len + 1);
 153           }
 154       }
 155
 156       if (file_name == NULL)
 157         /* Out of memory.  Treat the file as empty.  */
 158         cp = "";
 159       else
 160         {
 161           int fd;
 162
 163           /* Open the file.  Reject symbolic links on platforms that support
 164              O_NOFOLLOW.  This is a security feature.  Without it, an attacker
 165              could retrieve parts of the contents (namely, the tail of the
 166              first line that starts with "* ") of an arbitrary file by placing
 167              a symbolic link to that file under the name "charset.alias" in
 168              some writable directory and defining the environment variable
 169              CHARSETALIASDIR to point to that directory.  */
 170           fd = open (file_name,
 171                      O_RDONLY | (HAVE_WORKING_O_NOFOLLOW ? O_NOFOLLOW : 0));
 172           if (fd < 0)
 173             /* File not found.  Treat it as empty.  */
 174             cp = "";
 175           else
 176             {
 177               FILE *fp;
 178
 179               fp = fdopen (fd, "r");
 180               if (fp == NULL)
 181                 {
 182                   /* Out of memory.  Treat the file as empty.  */
 183                   close (fd);
 184                   cp = "";
 185                 }
 186               else
 187                 {
 188                   /* Parse the file's contents.  */
 189                   char *res_ptr = NULL;
 190                   size_t res_size = 0;
 191
 192                   for (;;)
 193                     {
 194                       int c;
 195                       char buf1[50+1];
 196                       char buf2[50+1];
 197                       size_t l1, l2;
 198                       char *old_res_ptr;
 199
 200                       c = getc (fp);
 201                       if (c == EOF)
 202                         break;
 203                       if (c == '\n' || c == ' ' || c == '\t')
 204                         continue;
 205                       if (c == '#')
 206                         {
 207                           /* Skip comment, to end of line.  */
 208                           do
 209                             c = getc (fp);
 210                           while (!(c == EOF || c == '\n'));
 211                           if (c == EOF)
 212                             break;
 213                           continue;
 214                         }
 215                       ungetc (c, fp);
 216                       if (fscanf (fp, "%50s %50s", buf1, buf2) < 2)
 217                         break;
 218                       l1 = strlen (buf1);
 219                       l2 = strlen (buf2);
 220                       old_res_ptr = res_ptr;
 221                       if (res_size == 0)
 222                         {
 223                           res_size = l1 + 1 + l2 + 1;
 224                           res_ptr = (char *) malloc (res_size + 1);
 225                         }
 226                       else
 227                         {
 228                           res_size += l1 + 1 + l2 + 1;
 229                           res_ptr = (char *) realloc (res_ptr, res_size + 1);
 230                         }
 231                       if (res_ptr == NULL)
 232                         {
 233                           /* Out of memory. */
 234                           res_size = 0;
 235                           free (old_res_ptr);
 236                           break;
 237                         }
 238                       strcpy (res_ptr + res_size - (l2 + 1) - (l1 + 1), buf1);
 239                       strcpy (res_ptr + res_size - (l2 + 1), buf2);
 240                     }
 241                   fclose (fp);
 242                   if (res_size == 0)
 243                     cp = "";
 244                   else
 245                     {
 246                       *(res_ptr + res_size) = '\0';
 247                       cp = res_ptr;
 248                     }
 249                 }
 250             }
 251
 252           free (file_name);
 253         }
 254
 255 #else
 256
 257 # if defined DARWIN7
 258       /* To avoid the trouble of installing a file that is shared by many
 259          GNU packages -- many packaging systems have problems with this --,
 260          simply inline the aliases here.  */
 261       cp = "ISO8859-1" "\0" "ISO-8859-1" "\0"
 262            "ISO8859-2" "\0" "ISO-8859-2" "\0"
 263            "ISO8859-4" "\0" "ISO-8859-4" "\0"
 264            "ISO8859-5" "\0" "ISO-8859-5" "\0"
 265            "ISO8859-7" "\0" "ISO-8859-7" "\0"
 266            "ISO8859-9" "\0" "ISO-8859-9" "\0"
 267            "ISO8859-13" "\0" "ISO-8859-13" "\0"
 268            "ISO8859-15" "\0" "ISO-8859-15" "\0"
 269            "KOI8-R" "\0" "KOI8-R" "\0"
 270            "KOI8-U" "\0" "KOI8-U" "\0"
 271            "CP866" "\0" "CP866" "\0"
 272            "CP949" "\0" "CP949" "\0"
 273            "CP1131" "\0" "CP1131" "\0"
 274            "CP1251" "\0" "CP1251" "\0"
 275            "eucCN" "\0" "GB2312" "\0"
 276            "GB2312" "\0" "GB2312" "\0"
 277            "eucJP" "\0" "EUC-JP" "\0"
 278            "eucKR" "\0" "EUC-KR" "\0"
 279            "Big5" "\0" "BIG5" "\0"
 280            "Big5HKSCS" "\0" "BIG5-HKSCS" "\0"
 281            "GBK" "\0" "GBK" "\0"
 282            "GB18030" "\0" "GB18030" "\0"
 283            "SJIS" "\0" "SHIFT_JIS" "\0"
 284            "ARMSCII-8" "\0" "ARMSCII-8" "\0"
 285            "PT154" "\0" "PT154" "\0"
 286          /*"ISCII-DEV" "\0" "?" "\0"*/
 287            "*" "\0" "UTF-8" "\0";
 288 # endif
 289
 290 # if defined VMS
 291       /* To avoid the troubles of an extra file charset.alias_vms in the
 292          sources of many GNU packages, simply inline the aliases here.  */
 293       /* The list of encodings is taken from the OpenVMS 7.3-1 documentation
 294          "Compaq C Run-Time Library Reference Manual for OpenVMS systems"
 295          section 10.7 "Handling Different Character Sets".  */
 296       cp = "ISO8859-1" "\0" "ISO-8859-1" "\0"
 297            "ISO8859-2" "\0" "ISO-8859-2" "\0"
 298            "ISO8859-5" "\0" "ISO-8859-5" "\0"
 299            "ISO8859-7" "\0" "ISO-8859-7" "\0"
 300            "ISO8859-8" "\0" "ISO-8859-8" "\0"
 301            "ISO8859-9" "\0" "ISO-8859-9" "\0"
 302            /* Japanese */
 303            "eucJP" "\0" "EUC-JP" "\0"
 304            "SJIS" "\0" "SHIFT_JIS" "\0"
 305            "DECKANJI" "\0" "DEC-KANJI" "\0"
 306            "SDECKANJI" "\0" "EUC-JP" "\0"
 307            /* Chinese */
 308            "eucTW" "\0" "EUC-TW" "\0"
 309            "DECHANYU" "\0" "DEC-HANYU" "\0"
 310            "DECHANZI" "\0" "GB2312" "\0"
 311            /* Korean */
 312            "DECKOREAN" "\0" "EUC-KR" "\0";
 313 # endif
 314
 315 # if defined WINDOWS_NATIVE || defined __CYGWIN__
 316       /* To avoid the troubles of installing a separate file in the same
 317          directory as the DLL and of retrieving the DLL's directory at
 318          runtime, simply inline the aliases here.  */
 319
 320       cp = "CP936" "\0" "GBK" "\0"
 321            "CP1361" "\0" "JOHAB" "\0"
 322            "CP20127" "\0" "ASCII" "\0"
 323            "CP20866" "\0" "KOI8-R" "\0"
 324            "CP20936" "\0" "GB2312" "\0"
 325            "CP21866" "\0" "KOI8-RU" "\0"
 326            "CP28591" "\0" "ISO-8859-1" "\0"
 327            "CP28592" "\0" "ISO-8859-2" "\0"
 328            "CP28593" "\0" "ISO-8859-3" "\0"
 329            "CP28594" "\0" "ISO-8859-4" "\0"
 330            "CP28595" "\0" "ISO-8859-5" "\0"
 331            "CP28596" "\0" "ISO-8859-6" "\0"
 332            "CP28597" "\0" "ISO-8859-7" "\0"
 333            "CP28598" "\0" "ISO-8859-8" "\0"
 334            "CP28599" "\0" "ISO-8859-9" "\0"
 335            "CP28605" "\0" "ISO-8859-15" "\0"
 336            "CP38598" "\0" "ISO-8859-8" "\0"
 337            "CP51932" "\0" "EUC-JP" "\0"
 338            "CP51936" "\0" "GB2312" "\0"
 339            "CP51949" "\0" "EUC-KR" "\0"
 340            "CP51950" "\0" "EUC-TW" "\0"
 341            "CP54936" "\0" "GB18030" "\0"
 342            "CP65001" "\0" "UTF-8" "\0";
 343 # endif
 344 #endif
 345
 346       charset_aliases = cp;
 347     }
 348
 349   return cp;
 350 }
 351
 352 /* Determine the current locale's character encoding, and canonicalize it
 353    into one of the canonical names listed in config.charset.
 354    The result must not be freed; it is statically allocated.
 355    If the canonical name cannot be determined, the result is a non-canonical
 356    name.  */
 357
 358 #ifdef STATIC
 359 STATIC
 360 #endif
 361 const char *
 362 locale_charset (void)
 363 {
 364   const char *codeset;
 365   const char *aliases;
 366
 367 #if !(defined WINDOWS_NATIVE || defined OS2)
 368
 369 # if HAVE_LANGINFO_CODESET
 370
 371   /* Most systems support nl_langinfo (CODESET) nowadays.  */
 372   codeset = nl_langinfo (CODESET);
 373
 374 #  ifdef __CYGWIN__
 375   /* Cygwin < 1.7 does not have locales.  nl_langinfo (CODESET) always
 376      returns "US-ASCII".  Return the suffix of the locale name from the
 377      environment variables (if present) or the codepage as a number.  */
 378   if (codeset != NULL && strcmp (codeset, "US-ASCII") == 0)
 379     {
 380       const char *locale;
 381       static char buf[2 + 10 + 1];
 382
 383       locale = getenv ("LC_ALL");
 384       if (locale == NULL || locale[0] == '\0')
 385         {
 386           locale = getenv ("LC_CTYPE");
 387           if (locale == NULL || locale[0] == '\0')
 388             locale = getenv ("LANG");
 389         }
 390       if (locale != NULL && locale[0] != '\0')
 391         {
 392           /* If the locale name contains an encoding after the dot, return
 393              it.  */
 394           const char *dot = strchr (locale, '.');
 395
 396           if (dot != NULL)
 397             {
 398               const char *modifier;
 399
 400               dot++;
 401               /* Look for the possible @... trailer and remove it, if any.  */
 402               modifier = strchr (dot, '@');
 403               if (modifier == NULL)
 404                 return dot;
 405               if (modifier - dot < sizeof (buf))
 406                 {
 407                   memcpy (buf, dot, modifier - dot);
 408                   buf [modifier - dot] = '\0';
 409                   return buf;
 410                 }
 411             }
 412         }
 413
 414       /* The Windows API has a function returning the locale's codepage as a
 415          number: GetACP().  This encoding is used by Cygwin, unless the user
 416          has set the environment variable CYGWIN=codepage:oem (which very few
 417          people do).
 418          Output directed to console windows needs to be converted (to
 419          GetOEMCP() if the console is using a raster font, or to
 420          GetConsoleOutputCP() if it is using a TrueType font).  Cygwin does
 421          this conversion transparently (see winsup/cygwin/fhandler_console.cc),
 422          converting to GetConsoleOutputCP().  This leads to correct results,
 423          except when SetConsoleOutputCP has been called and a raster font is
 424          in use.  */
 425       sprintf (buf, "CP%u", GetACP ());
 426       codeset = buf;
 427     }
 428 #  endif
 429
 430 # else
 431
 432   /* On old systems which lack it, use setlocale or getenv.  */
 433   const char *locale = NULL;
 434
 435   /* But most old systems don't have a complete set of locales.  Some
 436      (like SunOS 4 or DJGPP) have only the C locale.  Therefore we don't
 437      use setlocale here; it would return "C" when it doesn't support the
 438      locale name the user has set.  */
 439 #  if 0
 440   locale = setlocale (LC_CTYPE, NULL);
 441 #  endif
 442   if (locale == NULL || locale[0] == '\0')
 443     {
 444       locale = getenv ("LC_ALL");
 445       if (locale == NULL || locale[0] == '\0')
 446         {
 447           locale = getenv ("LC_CTYPE");
 448           if (locale == NULL || locale[0] == '\0')
 449             locale = getenv ("LANG");
 450         }
 451     }
 452
 453   /* On some old systems, one used to set locale = "iso8859_1". On others,
 454      you set it to "language_COUNTRY.charset". In any case, we resolve it
 455      through the charset.alias file.  */
 456   codeset = locale;
 457
 458 # endif
 459
 460 #elif defined WINDOWS_NATIVE
 461
 462   static char buf[2 + 10 + 1];
 463
 464   /* The Windows API has a function returning the locale's codepage as a
 465      number: GetACP().
 466      When the output goes to a console window, it needs to be provided in
 467      GetOEMCP() encoding if the console is using a raster font, or in
 468      GetConsoleOutputCP() encoding if it is using a TrueType font.
 469      But in GUI programs and for output sent to files and pipes, GetACP()
 470      encoding is the best bet.  */
 471   sprintf (buf, "CP%u", GetACP ());
 472   codeset = buf;
 473
 474 #elif defined OS2
 475
 476   const char *locale;
 477   static char buf[2 + 10 + 1];
 478   ULONG cp[3];
 479   ULONG cplen;
 480
 481   /* Allow user to override the codeset, as set in the operating system,
 482      with standard language environment variables.  */
 483   locale = getenv ("LC_ALL");
 484   if (locale == NULL || locale[0] == '\0')
 485     {
 486       locale = getenv ("LC_CTYPE");
 487       if (locale == NULL || locale[0] == '\0')
 488         locale = getenv ("LANG");
 489     }
 490   if (locale != NULL && locale[0] != '\0')
 491     {
 492       /* If the locale name contains an encoding after the dot, return it.  */
 493       const char *dot = strchr (locale, '.');
 494
 495       if (dot != NULL)
 496         {
 497           const char *modifier;
 498
 499           dot++;
 500           /* Look for the possible @... trailer and remove it, if any.  */
 501           modifier = strchr (dot, '@');
 502           if (modifier == NULL)
 503             return dot;
 504           if (modifier - dot < sizeof (buf))
 505             {
 506               memcpy (buf, dot, modifier - dot);
 507               buf [modifier - dot] = '\0';
 508               return buf;
 509             }
 510         }
 511
 512       /* Resolve through the charset.alias file.  */
 513       codeset = locale;
 514     }
 515   else
 516     {
 517       /* OS/2 has a function returning the locale's codepage as a number.  */
 518       if (DosQueryCp (sizeof (cp), cp, &cplen))
 519         codeset = "";
 520       else
 521         {
 522           sprintf (buf, "CP%u", cp[0]);
 523           codeset = buf;
 524         }
 525     }
 526
 527 #endif
 528
 529   if (codeset == NULL)
 530     /* The canonical name cannot be determined.  */
 531     codeset = "";
 532
 533   /* Resolve alias. */
 534   for (aliases = get_charset_aliases ();
 535        *aliases != '\0';
 536        aliases += strlen (aliases) + 1, aliases += strlen (aliases) + 1)
 537     if (strcmp (codeset, aliases) == 0
 538         || (aliases[0] == '*' && aliases[1] == '\0'))
 539       {
 540         codeset = aliases + strlen (aliases) + 1;
 541         break;
 542       }
 543
 544   /* Don't return an empty string.  GNU libc and GNU libiconv interpret
 545      the empty string as denoting "the locale's character encoding",
 546      thus GNU libiconv would call this function a second time.  */
 547   if (codeset[0] == '\0')
 548     codeset = "ASCII";
 549
 550 #ifdef DARWIN7
 551   /* Mac OS X sets MB_CUR_MAX to 1 when LC_ALL=C, and "UTF-8"
 552      (the default codeset) does not work when MB_CUR_MAX is 1.  */
 553   if (strcmp (codeset, "UTF-8") == 0 && MB_CUR_MAX_L (uselocale (NULL)) <= 1)
 554     codeset = "ASCII";
 555 #endif
 556
 557   return codeset;
 558 }