/* gcharset.c - Charset information

 *

 * Copyright (C) 2011 Red Hat, Inc.

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

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

 */

#include "config.h"

#include "gcharsetprivate.h"

#include "garray.h"

#include "genviron.h"

#include "ghash.h"

#include "gmessages.h"

#include "gstrfuncs.h"

#include "gthread.h"

#ifdef G_OS_WIN32

#include "gwin32.h"

#endif

#include "libcharset/libcharset.h"

#include <string.h>

#include <stdio.h>

G_LOCK_DEFINE_STATIC (aliases);

static GHashTable *

get_alias_hash (void)

{

  static GHashTable *alias_hash = NULL;

  const char *aliases;

  G_LOCK (aliases);

  if (!alias_hash)

    {

      alias_hash = g_hash_table_new (g_str_hash, g_str_equal);

      aliases = _g_locale_get_charset_aliases ();

      while (*aliases != '\0')

        {

          const char *canonical;

          const char *alias;

          const char **alias_array;

          int count = 0;

          alias = aliases;

          aliases += strlen (aliases) + 1;

          canonical = aliases;

          aliases += strlen (aliases) + 1;

          alias_array = g_hash_table_lookup (alias_hash, canonical);

          if (alias_array)

            {

              while (alias_array[count])

                count++;

            }

          alias_array = g_renew (const char *, alias_array, count + 2);

          alias_array[count] = alias;

          alias_array[count + 1] = NULL;

          g_hash_table_insert (alias_hash, (char *)canonical, alias_array);

        }

    }

  G_UNLOCK (aliases);

  return alias_hash;

}

/* As an abuse of the alias table, the following routines gets

 * the charsets that are aliases for the canonical name.

 */

const char **

_g_charset_get_aliases (const char *canonical_name)

{

  GHashTable *alias_hash = get_alias_hash ();

  return g_hash_table_lookup (alias_hash, canonical_name);

}

static gboolean

g_utf8_get_charset_internal (const char  *raw_data,

                             const char **a)

{

  const char *charset = g_getenv ("CHARSET");

  if (charset && *charset)

    {

      *a = charset;

      if (charset && strstr (charset, "UTF-8"))

        return TRUE;

      else

        return FALSE;

    }

  /* The libcharset code tries to be thread-safe without

   * a lock, but has a memory leak and a missing memory

   * barrier, so we lock for it

   */

  G_LOCK (aliases);

  charset = _g_locale_charset_unalias (raw_data);

  G_UNLOCK (aliases);

  if (charset && *charset)

    {

      *a = charset;

      if (charset && strstr (charset, "UTF-8"))

        return TRUE;

      else

        return FALSE;

    }

  /* Assume this for compatibility at present.  */

  *a = "US-ASCII";

  return FALSE;

}

typedef struct _GCharsetCache GCharsetCache;

struct _GCharsetCache {

  gboolean is_utf8;

  gchar *raw;

  gchar *charset;

};

static void

charset_cache_free (gpointer data)

{

  GCharsetCache *cache = data;

  g_free (cache->raw);

  g_free (cache->charset);

  g_free (cache);

}

/**

 * g_get_charset:

 * @charset: (out) (optional) (transfer none): return location for character set

 *   name, or %NULL.

 *

 * Obtains the character set for the [current locale][setlocale]; you

 * might use this character set as an argument to g_convert(), to convert

 * from the current locale's encoding to some other encoding. (Frequently

 * g_locale_to_utf8() and g_locale_from_utf8() are nice shortcuts, though.)

 *

 * On Windows the character set returned by this function is the

 * so-called system default ANSI code-page. That is the character set

 * used by the "narrow" versions of C library and Win32 functions that

 * handle file names. It might be different from the character set

 * used by the C library's current locale.

 *

 * On Linux, the character set is found by consulting nl_langinfo() if

 * available. If not, the environment variables `LC_ALL`, `LC_CTYPE`, `LANG`

 * and `CHARSET` are queried in order.

 *

 * The return value is %TRUE if the locale's encoding is UTF-8, in that

 * case you can perhaps avoid calling g_convert().

 *

 * The string returned in @charset is not allocated, and should not be

 * freed.

 *

 * Returns: %TRUE if the returned charset is UTF-8

 */

gboolean

g_get_charset (const char **charset)

{

  static GPrivate cache_private = G_PRIVATE_INIT (charset_cache_free);

  GCharsetCache *cache = g_private_get (&cache_private);

  const gchar *raw;

  if (!cache)

    {

      cache = g_new0 (GCharsetCache, 1);

      g_private_set (&cache_private, cache);

    }

  G_LOCK (aliases);

  raw = _g_locale_charset_raw ();

  G_UNLOCK (aliases);

  if (!(cache->raw && strcmp (cache->raw, raw) == 0))

    {

      const gchar *new_charset;

      g_free (cache->raw);

      g_free (cache->charset);

      cache->raw = g_strdup (raw);

      cache->is_utf8 = g_utf8_get_charset_internal (raw, &new_charset);

      cache->charset = g_strdup (new_charset);

    }

  if (charset)

    *charset = cache->charset;

  return cache->is_utf8;

}

/**

 * g_get_codeset:

 *

 * Gets the character set for the current locale.

 *

 * Returns: a newly allocated string containing the name

 *     of the character set. This string must be freed with g_free().

 */

gchar *

g_get_codeset (void)

{

  const gchar *charset;

  g_get_charset (&charset);

  return g_strdup (charset);

}

#ifndef G_OS_WIN32

/* read an alias file for the locales */

static void

read_aliases (gchar      *file,

              GHashTable *alias_table)

{

  FILE *fp;

  char buf[256];

  fp = fopen (file,"r");

  if (!fp)

    return;

  while (fgets (buf, 256, fp))

    {

      char *p, *q;

      g_strstrip (buf);

      /* Line is a comment */

      if ((buf[0] == '#') || (buf[0] == '\0'))

        continue;

      /* Reads first column */

      for (p = buf, q = NULL; *p; p++) {

        if ((*p == '\t') || (*p == ' ') || (*p == ':')) {

          *p = '\0';

          q = p+1;

          while ((*q == '\t') || (*q == ' ')) {

            q++;

          }

          break;

        }

      }

      /* The line only had one column */

      if (!q || *q == '\0')

        continue;

      /* Read second column */

      for (p = q; *p; p++) {

        if ((*p == '\t') || (*p == ' ')) {

          *p = '\0';

          break;

        }

      }

      /* Add to alias table if necessary */

      if (!g_hash_table_lookup (alias_table, buf)) {

        g_hash_table_insert (alias_table, g_strdup (buf), g_strdup (q));

      }

    }

  fclose (fp);

}

#endif

static char *

unalias_lang (char *lang)

{

#ifndef G_OS_WIN32

  static GHashTable *alias_table = NULL;

  char *p;

  int i;

  if (g_once_init_enter (&alias_table))

    {

      GHashTable *table = g_hash_table_new (g_str_hash, g_str_equal);

      read_aliases ("/usr/share/locale/locale.alias", table);

      g_once_init_leave (&alias_table, table);

    }

  i = 0;

  while ((p = g_hash_table_lookup (alias_table, lang)) && (strcmp (p, lang) != 0))

    {

      lang = p;

      if (i++ == 30)

        {

          static gboolean said_before = FALSE;

          if (!said_before)

            g_warning ("Too many alias levels for a locale, "

                       "may indicate a loop");

          said_before = TRUE;

          return lang;

        }

    }

#endif

  return lang;

}

/* Mask for components of locale spec. The ordering here is from

 * least significant to most significant

 */

enum

{

  COMPONENT_CODESET =   1 << 0,

  COMPONENT_TERRITORY = 1 << 1,

  COMPONENT_MODIFIER =  1 << 2

};

/* Break an X/Open style locale specification into components

 */

static guint

explode_locale (const gchar *locale,

                gchar      **language,

                gchar      **territory,

                gchar      **codeset,

                gchar      **modifier)

{

  const gchar *uscore_pos;

  const gchar *at_pos;

  const gchar *dot_pos;

  guint mask = 0;

  uscore_pos = strchr (locale, '_');

  dot_pos = strchr (uscore_pos ? uscore_pos : locale, '.');

  at_pos = strchr (dot_pos ? dot_pos : (uscore_pos ? uscore_pos : locale), '@');

  if (at_pos)

    {

      mask |= COMPONENT_MODIFIER;

      *modifier = g_strdup (at_pos);

    }

  else

    at_pos = locale + strlen (locale);

  if (dot_pos)

    {

      mask |= COMPONENT_CODESET;

      *codeset = g_strndup (dot_pos, at_pos - dot_pos);

    }

  else

    dot_pos = at_pos;

  if (uscore_pos)

    {

      mask |= COMPONENT_TERRITORY;

      *territory = g_strndup (uscore_pos, dot_pos - uscore_pos);

    }

  else

    uscore_pos = dot_pos;

  *language = g_strndup (locale, uscore_pos - locale);

  return mask;

}

/*

 * Compute all interesting variants for a given locale name -

 * by stripping off different components of the value.

 *

 * For simplicity, we assume that the locale is in

 * X/Open format: language[_territory][.codeset][@modifier]

 *

 * TODO: Extend this to handle the CEN format (see the GNUlibc docs)

 *       as well. We could just copy the code from glibc wholesale

 *       but it is big, ugly, and complicated, so I'm reluctant

 *       to do so when this should handle 99% of the time...

 */

static void

append_locale_variants (GPtrArray *array,

                        const gchar *locale)

{

  gchar *language = NULL;

  gchar *territory = NULL;

  gchar *codeset = NULL;

  gchar *modifier = NULL;

  guint mask;

  guint i, j;

  g_return_if_fail (locale != NULL);

  mask = explode_locale (locale, &language, &territory, &codeset, &modifier);

  /* Iterate through all possible combinations, from least attractive

   * to most attractive.

   */

  for (j = 0; j <= mask; ++j)

    {

      i = mask - j;

      if ((i & ~mask) == 0)

        {

          gchar *val = g_strconcat (language,

                                    (i & COMPONENT_TERRITORY) ? territory : "",

                                    (i & COMPONENT_CODESET) ? codeset : "",

                                    (i & COMPONENT_MODIFIER) ? modifier : "",

                                    NULL);

          g_ptr_array_add (array, val);

        }

    }

  g_free (language);

  if (mask & COMPONENT_CODESET)

    g_free (codeset);

  if (mask & COMPONENT_TERRITORY)

    g_free (territory);

  if (mask & COMPONENT_MODIFIER)

    g_free (modifier);

}

/**

 * g_get_locale_variants:

 * @locale: a locale identifier

 *

 * Returns a list of derived variants of @locale, which can be used to

 * e.g. construct locale-dependent filenames or search paths. The returned

 * list is sorted from most desirable to least desirable.

 * This function handles territory, charset and extra locale modifiers.

 *

 * For example, if @locale is "fr_BE", then the returned list

 * is "fr_BE", "fr".

 *

 * If you need the list of variants for the current locale,

 * use g_get_language_names().

 *

 * Returns: (transfer full) (array zero-terminated=1) (element-type utf8): a newly

 *   allocated array of newly allocated strings with the locale variants. Free with

 *   g_strfreev().

 *

 * Since: 2.28

 */

gchar **

g_get_locale_variants (const gchar *locale)

{

  GPtrArray *array;

  g_return_val_if_fail (locale != NULL, NULL);

  array = g_ptr_array_sized_new (8);

  append_locale_variants (array, locale);

  g_ptr_array_add (array, NULL);

  return (gchar **) g_ptr_array_free (array, FALSE);

}

/* The following is (partly) taken from the gettext package.

   Copyright (C) 1995, 1996, 1997, 1998 Free Software Foundation, Inc.  */

static const gchar *

guess_category_value (const gchar *category_name)

{

  const gchar *retval;

  /* The highest priority value is the 'LANGUAGE' environment

     variable.  This is a GNU extension.  */

  retval = g_getenv ("LANGUAGE");

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

    return retval;

  /* 'LANGUAGE' is not set.  So we have to proceed with the POSIX

     methods of looking to 'LC_ALL', 'LC_xxx', and 'LANG'.  On some

     systems this can be done by the 'setlocale' function itself.  */

  /* Setting of LC_ALL overwrites all other.  */

  retval = g_getenv ("LC_ALL");

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

    return retval;

  /* Next comes the name of the desired category.  */

  retval = g_getenv (category_name);

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

    return retval;

  /* Last possibility is the LANG environment variable.  */

  retval = g_getenv ("LANG");

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

    return retval;

#ifdef G_PLATFORM_WIN32

  /* g_win32_getlocale() first checks for LC_ALL, LC_MESSAGES and

   * LANG, which we already did above. Oh well. The main point of

   * calling g_win32_getlocale() is to get the thread's locale as used

   * by Windows and the Microsoft C runtime (in the "English_United

   * States" format) translated into the Unixish format.

   */

  {

    char *locale = g_win32_getlocale ();

    retval = g_intern_string (locale);

    g_free (locale);

    return retval;

  }

#endif

  return NULL;

}

typedef struct _GLanguageNamesCache GLanguageNamesCache;

struct _GLanguageNamesCache {

  gchar *languages;

  gchar **language_names;

};

static void

language_names_cache_free (gpointer data)

{

  GLanguageNamesCache *cache = data;

  g_free (cache->languages);

  g_strfreev (cache->language_names);

  g_free (cache);

}

/**

 * g_get_language_names:

 *

 * Computes a list of applicable locale names, which can be used to

 * e.g. construct locale-dependent filenames or search paths. The returned

 * list is sorted from most desirable to least desirable and always contains

 * the default locale "C".

 *

 * For example, if LANGUAGE=de:en_US, then the returned list is

 * "de", "en_US", "en", "C".

 *

 * This function consults the environment variables `LANGUAGE`, `LC_ALL`,

 * `LC_MESSAGES` and `LANG` to find the list of locales specified by the

 * user.

 *

 * Returns: (array zero-terminated=1) (transfer none): a %NULL-terminated array of strings owned by GLib

 *    that must not be modified or freed.

 *

 * Since: 2.6

 **/

const gchar * const *

g_get_language_names (void)

{

  static GPrivate cache_private = G_PRIVATE_INIT (language_names_cache_free);

  GLanguageNamesCache *cache = g_private_get (&cache_private);

  const gchar *value;

  if (!cache)

    {

      cache = g_new0 (GLanguageNamesCache, 1);

      g_private_set (&cache_private, cache);

    }

  value = guess_category_value ("LC_MESSAGES");

  if (!value)

    value = "C";

  if (!(cache->languages && strcmp (cache->languages, value) == 0))

    {

      GPtrArray *array;

      gchar **alist, **a;

      g_free (cache->languages);

      g_strfreev (cache->language_names);

      cache->languages = g_strdup (value);

      array = g_ptr_array_sized_new (8);

      alist = g_strsplit (value, ":", 0);

      for (a = alist; *a; a++)

        append_locale_variants (array, unalias_lang (*a));

      g_strfreev (alist);

      g_ptr_array_add (array, g_strdup ("C"));

      g_ptr_array_add (array, NULL);

      cache->language_names = (gchar **) g_ptr_array_free (array, FALSE);

    }

  return (const gchar * const *) cache->language_names;

}