/* Determine a canonical name for the current locale's character encoding.

   Copyright (C) 2000-2006, 2008-2015 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3, or (at your option)

   any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License along

   with this program; if not, see <http://www.gnu.org/licenses/>.  */

/* Written by Bruno Haible <bruno@clisp.org>.  */

#include <config.h>

/* Specification.  */

#include "localcharset.h"

#include <fcntl.h>

#include <stddef.h>

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#if defined __APPLE__ && defined __MACH__ && HAVE_LANGINFO_CODESET

# define DARWIN7 /* Darwin 7 or newer, i.e. Mac OS X 10.3 or newer */

#endif

#if defined _WIN32 || defined __WIN32__

# define WINDOWS_NATIVE

# include <locale.h>

#endif

#if defined __EMX__

/* Assume EMX program runs on OS/2, even if compiled under DOS.  */

# ifndef OS2

#  define OS2

# endif

#endif

#if !defined WINDOWS_NATIVE

# include <unistd.h>

# if HAVE_LANGINFO_CODESET

#  include <langinfo.h>

# else

#  if 0 /* see comment below */

#   include <locale.h>

#  endif

# endif

# ifdef __CYGWIN__

#  define WIN32_LEAN_AND_MEAN

#  include <windows.h>

# endif

#elif defined WINDOWS_NATIVE

# define WIN32_LEAN_AND_MEAN

# include <windows.h>

#endif

#if defined OS2

# define INCL_DOS

# include <os2.h>

#endif

/* For MB_CUR_MAX_L */

#if defined DARWIN7

# include <xlocale.h>

#endif

#if ENABLE_RELOCATABLE

# include "relocatable.h"

#else

# define relocate(pathname) (pathname)

#endif

/* Get LIBDIR.  */

#ifndef LIBDIR

# include "configmake.h"

#endif

/* Define O_NOFOLLOW to 0 on platforms where it does not exist.  */

#ifndef O_NOFOLLOW

# define O_NOFOLLOW 0

#endif

#if defined _WIN32 || defined __WIN32__ || defined __CYGWIN__ || defined __EMX__ || defined __DJGPP__

  /* Native Windows, Cygwin, OS/2, DOS */

# define ISSLASH(C) ((C) == '/' || (C) == '\\')

#endif

#ifndef DIRECTORY_SEPARATOR

# define DIRECTORY_SEPARATOR '/'

#endif

#ifndef ISSLASH

# define ISSLASH(C) ((C) == DIRECTORY_SEPARATOR)

#endif

#if HAVE_DECL_GETC_UNLOCKED

# undef getc

# define getc getc_unlocked

#endif

/* The following static variable is declared 'volatile' to avoid a

   possible multithread problem in the function get_charset_aliases. If we

   are running in a threaded environment, and if two threads initialize

   'charset_aliases' simultaneously, both will produce the same value,

   and everything will be ok if the two assignments to 'charset_aliases'

   are atomic. But I don't know what will happen if the two assignments mix.  */

#if __STDC__ != 1

# define volatile /* empty */

#endif

/* Pointer to the contents of the charset.alias file, if it has already been

   read, else NULL.  Its format is:

   ALIAS_1 '\0' CANONICAL_1 '\0' ... ALIAS_n '\0' CANONICAL_n '\0' '\0'  */

static const char * volatile charset_aliases;

/* Return a pointer to the contents of the charset.alias file.  */

static const char *

get_charset_aliases (void)

{

  const char *cp;

  cp = charset_aliases;

  if (cp == NULL)

    {

#if !(defined DARWIN7 || defined VMS || defined WINDOWS_NATIVE || defined __CYGWIN__ || defined OS2)

      const char *dir;

      const char *base = "charset.alias";

      char *file_name;

      /* Make it possible to override the charset.alias location.  This is

         necessary for running the testsuite before "make install".  */

      dir = getenv ("CHARSETALIASDIR");

      if (dir == NULL || dir[0] == '\0')

        dir = relocate (LIBDIR);

      /* Concatenate dir and base into freshly allocated file_name.  */

      {

        size_t dir_len = strlen (dir);

        size_t base_len = strlen (base);

        int add_slash = (dir_len > 0 && !ISSLASH (dir[dir_len - 1]));

        file_name = (char *) malloc (dir_len + add_slash + base_len + 1);

        if (file_name != NULL)

          {

            memcpy (file_name, dir, dir_len);

            if (add_slash)

              file_name[dir_len] = DIRECTORY_SEPARATOR;

            memcpy (file_name + dir_len + add_slash, base, base_len + 1);

          }

      }

      if (file_name == NULL)

        /* Out of memory.  Treat the file as empty.  */

        cp = "";

      else

        {

          int fd;

          /* Open the file.  Reject symbolic links on platforms that support

             O_NOFOLLOW.  This is a security feature.  Without it, an attacker

             could retrieve parts of the contents (namely, the tail of the

             first line that starts with "* ") of an arbitrary file by placing

             a symbolic link to that file under the name "charset.alias" in

             some writable directory and defining the environment variable

             CHARSETALIASDIR to point to that directory.  */

          fd = open (file_name,

                     O_RDONLY | (HAVE_WORKING_O_NOFOLLOW ? O_NOFOLLOW : 0));

          if (fd < 0)

            /* File not found.  Treat it as empty.  */

            cp = "";

          else

            {

              FILE *fp;

              fp = fdopen (fd, "r");

              if (fp == NULL)

                {

                  /* Out of memory.  Treat the file as empty.  */

                  close (fd);

                  cp = "";

                }

              else

                {

                  /* Parse the file's contents.  */

                  char *res_ptr = NULL;

                  size_t res_size = 0;

                  for (;;)

                    {

                      int c;

                      char buf1[50+1];

                      char buf2[50+1];

                      size_t l1, l2;

                      char *old_res_ptr;

                      c = getc (fp);

                      if (c == EOF)

                        break;

                      if (c == '\n' || c == ' ' || c == '\t')

                        continue;

                      if (c == '#')

                        {

                          /* Skip comment, to end of line.  */

                          do

                            c = getc (fp);

                          while (!(c == EOF || c == '\n'));

                          if (c == EOF)

                            break;

                          continue;

                        }

                      ungetc (c, fp);

                      if (fscanf (fp, "%50s %50s", buf1, buf2) < 2)

                        break;

                      l1 = strlen (buf1);

                      l2 = strlen (buf2);

                      old_res_ptr = res_ptr;

                      if (res_size == 0)

                        {

                          res_size = l1 + 1 + l2 + 1;

                          res_ptr = (char *) malloc (res_size + 1);

                        }

                      else

                        {

                          res_size += l1 + 1 + l2 + 1;

                          res_ptr = (char *) realloc (res_ptr, res_size + 1);

                        }

                      if (res_ptr == NULL)

                        {

                          /* Out of memory. */

                          res_size = 0;

                          free (old_res_ptr);

                          break;

                        }

                      strcpy (res_ptr + res_size - (l2 + 1) - (l1 + 1), buf1);

                      strcpy (res_ptr + res_size - (l2 + 1), buf2);

                    }

                  fclose (fp);

                  if (res_size == 0)

                    cp = "";

                  else

                    {

                      *(res_ptr + res_size) = '\0';

                      cp = res_ptr;

                    }

                }

            }

          free (file_name);

        }

#else

# if defined DARWIN7

      /* To avoid the trouble of installing a file that is shared by many

         GNU packages -- many packaging systems have problems with this --,

         simply inline the aliases here.  */

      cp = "ISO8859-1" "\0" "ISO-8859-1" "\0"

           "ISO8859-2" "\0" "ISO-8859-2" "\0"

           "ISO8859-4" "\0" "ISO-8859-4" "\0"

           "ISO8859-5" "\0" "ISO-8859-5" "\0"

           "ISO8859-7" "\0" "ISO-8859-7" "\0"

           "ISO8859-9" "\0" "ISO-8859-9" "\0"

           "ISO8859-13" "\0" "ISO-8859-13" "\0"

           "ISO8859-15" "\0" "ISO-8859-15" "\0"

           "KOI8-R" "\0" "KOI8-R" "\0"

           "KOI8-U" "\0" "KOI8-U" "\0"

           "CP866" "\0" "CP866" "\0"

           "CP949" "\0" "CP949" "\0"

           "CP1131" "\0" "CP1131" "\0"

           "CP1251" "\0" "CP1251" "\0"

           "eucCN" "\0" "GB2312" "\0"

           "GB2312" "\0" "GB2312" "\0"

           "eucJP" "\0" "EUC-JP" "\0"

           "eucKR" "\0" "EUC-KR" "\0"

           "Big5" "\0" "BIG5" "\0"

           "Big5HKSCS" "\0" "BIG5-HKSCS" "\0"

           "GBK" "\0" "GBK" "\0"

           "GB18030" "\0" "GB18030" "\0"

           "SJIS" "\0" "SHIFT_JIS" "\0"

           "ARMSCII-8" "\0" "ARMSCII-8" "\0"

           "PT154" "\0" "PT154" "\0"

         /*"ISCII-DEV" "\0" "?" "\0"*/

           "*" "\0" "UTF-8" "\0";

# endif

# if defined VMS

      /* To avoid the troubles of an extra file charset.alias_vms in the

         sources of many GNU packages, simply inline the aliases here.  */

      /* The list of encodings is taken from the OpenVMS 7.3-1 documentation

         "Compaq C Run-Time Library Reference Manual for OpenVMS systems"

         section 10.7 "Handling Different Character Sets".  */

      cp = "ISO8859-1" "\0" "ISO-8859-1" "\0"

           "ISO8859-2" "\0" "ISO-8859-2" "\0"

           "ISO8859-5" "\0" "ISO-8859-5" "\0"

           "ISO8859-7" "\0" "ISO-8859-7" "\0"

           "ISO8859-8" "\0" "ISO-8859-8" "\0"

           "ISO8859-9" "\0" "ISO-8859-9" "\0"

           /* Japanese */

           "eucJP" "\0" "EUC-JP" "\0"

           "SJIS" "\0" "SHIFT_JIS" "\0"

           "DECKANJI" "\0" "DEC-KANJI" "\0"

           "SDECKANJI" "\0" "EUC-JP" "\0"

           /* Chinese */

           "eucTW" "\0" "EUC-TW" "\0"

           "DECHANYU" "\0" "DEC-HANYU" "\0"

           "DECHANZI" "\0" "GB2312" "\0"

           /* Korean */

           "DECKOREAN" "\0" "EUC-KR" "\0";

# endif

# if defined WINDOWS_NATIVE || defined __CYGWIN__

      /* To avoid the troubles of installing a separate file in the same

         directory as the DLL and of retrieving the DLL's directory at

         runtime, simply inline the aliases here.  */

      cp = "CP936" "\0" "GBK" "\0"

           "CP1361" "\0" "JOHAB" "\0"

           "CP20127" "\0" "ASCII" "\0"

           "CP20866" "\0" "KOI8-R" "\0"

           "CP20936" "\0" "GB2312" "\0"

           "CP21866" "\0" "KOI8-RU" "\0"

           "CP28591" "\0" "ISO-8859-1" "\0"

           "CP28592" "\0" "ISO-8859-2" "\0"

           "CP28593" "\0" "ISO-8859-3" "\0"

           "CP28594" "\0" "ISO-8859-4" "\0"

           "CP28595" "\0" "ISO-8859-5" "\0"

           "CP28596" "\0" "ISO-8859-6" "\0"

           "CP28597" "\0" "ISO-8859-7" "\0"

           "CP28598" "\0" "ISO-8859-8" "\0"

           "CP28599" "\0" "ISO-8859-9" "\0"

           "CP28605" "\0" "ISO-8859-15" "\0"

           "CP38598" "\0" "ISO-8859-8" "\0"

           "CP51932" "\0" "EUC-JP" "\0"

           "CP51936" "\0" "GB2312" "\0"

           "CP51949" "\0" "EUC-KR" "\0"

           "CP51950" "\0" "EUC-TW" "\0"

           "CP54936" "\0" "GB18030" "\0"

           "CP65001" "\0" "UTF-8" "\0";

# endif

# if defined OS2

      /* To avoid the troubles of installing a separate file in the same

         directory as the DLL and of retrieving the DLL's directory at

         runtime, simply inline the aliases here.  */

      /* The list of encodings is taken from "List of OS/2 Codepages"

         by Alex Taylor:

         <http://altsan.org/os2/toolkits/uls/index.html#codepages>.

         See also "IBM Globalization - Code page identifiers":

         <http://www-01.ibm.com/software/globalization/cp/cp_cpgid.html>.  */

      cp = "CP813" "\0" "ISO-8859-7" "\0"

           "CP878" "\0" "KOI8-R" "\0"

           "CP819" "\0" "ISO-8859-1" "\0"

           "CP912" "\0" "ISO-8859-2" "\0"

           "CP913" "\0" "ISO-8859-3" "\0"

           "CP914" "\0" "ISO-8859-4" "\0"

           "CP915" "\0" "ISO-8859-5" "\0"

           "CP916" "\0" "ISO-8859-8" "\0"

           "CP920" "\0" "ISO-8859-9" "\0"

           "CP921" "\0" "ISO-8859-13" "\0"

           "CP923" "\0" "ISO-8859-15" "\0"

           "CP954" "\0" "EUC-JP" "\0"

           "CP964" "\0" "EUC-TW" "\0"

           "CP970" "\0" "EUC-KR" "\0"

           "CP1089" "\0" "ISO-8859-6" "\0"

           "CP1208" "\0" "UTF-8" "\0"

           "CP1381" "\0" "GB2312" "\0"

           "CP1386" "\0" "GBK" "\0"

           "CP3372" "\0" "EUC-JP" "\0";

# endif

#endif

      charset_aliases = cp;

    }

  return cp;

}

/* Determine the current locale's character encoding, and canonicalize it

   into one of the canonical names listed in config.charset.

   The result must not be freed; it is statically allocated.

   If the canonical name cannot be determined, the result is a non-canonical

   name.  */

#ifdef STATIC

STATIC

#endif

const char *

locale_charset (void)

{

  const char *codeset;

  const char *aliases;

#if !(defined WINDOWS_NATIVE || defined OS2)

# if HAVE_LANGINFO_CODESET

  /* Most systems support nl_langinfo (CODESET) nowadays.  */

  codeset = nl_langinfo (CODESET);

#  ifdef __CYGWIN__

  /* Cygwin < 1.7 does not have locales.  nl_langinfo (CODESET) always

     returns "US-ASCII".  Return the suffix of the locale name from the

     environment variables (if present) or the codepage as a number.  */

  if (codeset != NULL && strcmp (codeset, "US-ASCII") == 0)

    {

      const char *locale;

      static char buf[2 + 10 + 1];

      locale = getenv ("LC_ALL");

      if (locale == NULL || locale[0] == '\0')

        {

          locale = getenv ("LC_CTYPE");

          if (locale == NULL || locale[0] == '\0')

            locale = getenv ("LANG");

        }

      if (locale != NULL && locale[0] != '\0')

        {

          /* If the locale name contains an encoding after the dot, return

             it.  */

          const char *dot = strchr (locale, '.');

          if (dot != NULL)

            {

              const char *modifier;

              dot++;

              /* Look for the possible @... trailer and remove it, if any.  */

              modifier = strchr (dot, '@');

              if (modifier == NULL)

                return dot;

              if (modifier - dot < sizeof (buf))

                {

                  memcpy (buf, dot, modifier - dot);

                  buf [modifier - dot] = '\0';

                  return buf;

                }

            }

        }

      /* The Windows API has a function returning the locale's codepage as a

         number: GetACP().  This encoding is used by Cygwin, unless the user

         has set the environment variable CYGWIN=codepage:oem (which very few

         people do).

         Output directed to console windows needs to be converted (to

         GetOEMCP() if the console is using a raster font, or to

         GetConsoleOutputCP() if it is using a TrueType font).  Cygwin does

         this conversion transparently (see winsup/cygwin/fhandler_console.cc),

         converting to GetConsoleOutputCP().  This leads to correct results,

         except when SetConsoleOutputCP has been called and a raster font is

         in use.  */

      sprintf (buf, "CP%u", GetACP ());

      codeset = buf;

    }

#  endif

# else

  /* On old systems which lack it, use setlocale or getenv.  */

  const char *locale = NULL;

  /* But most old systems don't have a complete set of locales.  Some

     (like SunOS 4 or DJGPP) have only the C locale.  Therefore we don't

     use setlocale here; it would return "C" when it doesn't support the

     locale name the user has set.  */

#  if 0

  locale = setlocale (LC_CTYPE, NULL);

#  endif

  if (locale == NULL || locale[0] == '\0')

    {

      locale = getenv ("LC_ALL");

      if (locale == NULL || locale[0] == '\0')

        {

          locale = getenv ("LC_CTYPE");

          if (locale == NULL || locale[0] == '\0')

            locale = getenv ("LANG");

        }

    }

  /* On some old systems, one used to set locale = "iso8859_1". On others,

     you set it to "language_COUNTRY.charset". In any case, we resolve it

     through the charset.alias file.  */

  codeset = locale;

# endif

#elif defined WINDOWS_NATIVE

  static char buf[2 + 10 + 1];

  /* The Windows API has a function returning the locale's codepage as

     a number, but the value doesn't change according to what the

     'setlocale' call specified.  So we use it as a last resort, in

     case the string returned by 'setlocale' doesn't specify the

     codepage.  */

  char *current_locale = setlocale (LC_ALL, NULL);

  char *pdot;

  /* If they set different locales for different categories,

     'setlocale' will return a semi-colon separated list of locale

     values.  To make sure we use the correct one, we choose LC_CTYPE.  */

  if (strchr (current_locale, ';'))

    current_locale = setlocale (LC_CTYPE, NULL);

  pdot = strrchr (current_locale, '.');

  if (pdot)

    sprintf (buf, "CP%s", pdot + 1);

  else

    {

      /* The Windows API has a function returning the locale's codepage as a

        number: GetACP().

        When the output goes to a console window, it needs to be provided in

        GetOEMCP() encoding if the console is using a raster font, or in

        GetConsoleOutputCP() encoding if it is using a TrueType font.

        But in GUI programs and for output sent to files and pipes, GetACP()

        encoding is the best bet.  */

      sprintf (buf, "CP%u", GetACP ());

    }

  codeset = buf;

#elif defined OS2

  const char *locale;

  static char buf[2 + 10 + 1];

  ULONG cp[3];

  ULONG cplen;

  codeset = NULL;

  /* Allow user to override the codeset, as set in the operating system,

     with standard language environment variables.  */

  locale = getenv ("LC_ALL");

  if (locale == NULL || locale[0] == '\0')

    {

      locale = getenv ("LC_CTYPE");

      if (locale == NULL || locale[0] == '\0')

        locale = getenv ("LANG");

    }

  if (locale != NULL && locale[0] != '\0')

    {

      /* If the locale name contains an encoding after the dot, return it.  */

      const char *dot = strchr (locale, '.');

      if (dot != NULL)

        {

          const char *modifier;

          dot++;

          /* Look for the possible @... trailer and remove it, if any.  */

          modifier = strchr (dot, '@');

          if (modifier == NULL)

            return dot;

          if (modifier - dot < sizeof (buf))

            {

              memcpy (buf, dot, modifier - dot);

              buf [modifier - dot] = '\0';

              return buf;

            }

        }

      /* For the POSIX locale, don't use the system's codepage.  */

      if (strcmp (locale, "C") == 0 || strcmp (locale, "POSIX") == 0)

        codeset = "";

    }

  if (codeset == NULL)

    {

      /* OS/2 has a function returning the locale's codepage as a number.  */

      if (DosQueryCp (sizeof (cp), cp, &cplen))

        codeset = "";

      else

        {

          sprintf (buf, "CP%u", cp[0]);

          codeset = buf;

        }

    }

#endif

  if (codeset == NULL)

    /* The canonical name cannot be determined.  */

    codeset = "";

  /* Resolve alias. */

  for (aliases = get_charset_aliases ();

       *aliases != '\0';

       aliases += strlen (aliases) + 1, aliases += strlen (aliases) + 1)

    if (strcmp (codeset, aliases) == 0

        || (aliases[0] == '*' && aliases[1] == '\0'))

      {

        codeset = aliases + strlen (aliases) + 1;

        break;

      }

  /* Don't return an empty string.  GNU libc and GNU libiconv interpret

     the empty string as denoting "the locale's character encoding",

     thus GNU libiconv would call this function a second time.  */

  if (codeset[0] == '\0')

    codeset = "ASCII";

#ifdef DARWIN7

  /* Mac OS X sets MB_CUR_MAX to 1 when LC_ALL=C, and "UTF-8"

     (the default codeset) does not work when MB_CUR_MAX is 1.  */

  if (strcmp (codeset, "UTF-8") == 0 && MB_CUR_MAX_L (uselocale (NULL)) <= 1)

    codeset = "ASCII";

#endif

  return codeset;

}