[thirdparty/e2fsprogs.git] / intl / localcharset.c

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

   Copyright (C) 2000-2003 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify it
   under the terms of the GNU Library General Public License as published
   by the Free Software Foundation; either version 2, 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
   USA.  */

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

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

/* Specification.  */
#include "localcharset.h"

#if HAVE_STDDEF_H
# include <stddef.h>
#endif

#include <stdio.h>
#if HAVE_STRING_H
# include <string.h>
#else
# include <strings.h>
#endif
#if HAVE_STDLIB_H
# include <stdlib.h>
#endif

#if defined _WIN32 || defined __WIN32__
# undef WIN32   /* avoid warning on mingw32 */
# define WIN32
#endif

#if defined __EMX__
/* Assume EMX program runs on OS/2, even if compiled under DOS.  */
# define OS2
#endif

#if !defined WIN32
# if HAVE_LANGINFO_CODESET
#  include <langinfo.h>
# else
#  if HAVE_SETLOCALE
#   include <locale.h>
#  endif
# endif
#elif defined WIN32
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
#endif
#if defined OS2
# define INCL_DOS
# include <os2.h>
#endif

#if ENABLE_RELOCATABLE
# include "relocatable.h"
#else
# define relocate(pathname) (pathname)
#endif

#if defined _WIN32 || defined __WIN32__ || defined __EMX__ || defined __DJGPP__
  /* Win32, 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 ()
{
  const char *cp;

  cp = charset_aliases;
  if (cp == NULL)
    {
#if !(defined VMS || defined WIN32)
      FILE *fp;
      const char *dir = relocate (LIBDIR);
      const char *base = "charset.alias";
      char *file_name;

      /* 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 || (fp = fopen (file_name, "r")) == NULL)
	/* Out of memory or file not found, treat it as empty.  */
	cp = "";
      else
	{
	  /* Parse the file's contents.  */
	  int c;
	  char buf1[50+1];
	  char buf2[50+1];
	  char *res_ptr = NULL;
	  size_t res_size = 0;
	  size_t l1, l2;

	  for (;;)
	    {
	      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);
	      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;
		  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 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 WIN32
      /* 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"
	   "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";
# 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 ()
{
  const char *codeset;
  const char *aliases;

#if !(defined WIN32 || defined OS2)

# if HAVE_LANGINFO_CODESET

  /* Most systems support nl_langinfo (CODESET) nowadays.  */
  codeset = nl_langinfo (CODESET);

# 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 HAVE_SETLOCALE && 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 WIN32

  static char buf[2 + 10 + 1];

  /* Woe32 has a function returning the locale's codepage as a number.  */
  sprintf (buf, "CP%u", GetACP ());
  codeset = buf;

#elif defined OS2

  const char *locale;
  static char buf[2 + 10 + 1];
  ULONG cp[3];
  ULONG cplen;

  /* 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;
	    }
	}

      /* Resolve through the charset.alias file.  */
      codeset = locale;
    }
  else
    {
      /* 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";

  return codeset;
}
Commit	Line	Data
a04eba3f TT	1	/* Determine a canonical name for the current locale's character encoding.
a04eba3f TT	2
b0cacab0	3	Copyright (C) 2000-2003 Free Software Foundation, Inc.
a04eba3f TT	4
	5	This program is free software; you can redistribute it and/or modify it
	6	under the terms of the GNU Library General Public License as published
	7	by 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 GNU
	13	Library General Public License for more details.
	14
	15	You should have received a copy of the GNU Library General Public
	16	License along with this program; if not, write to the Free Software
8785aaea	17	Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
a04eba3f TT	18	USA. */
	19
	20	/* Written by Bruno Haible <bruno@clisp.org>. */
	21
	22	#ifdef HAVE_CONFIG_H
	23	# include <config.h>
	24	#endif
	25
b0cacab0 TT	26	/* Specification. */
	27	#include "localcharset.h"
	28
a04eba3f TT	29	#if HAVE_STDDEF_H
	30	# include <stddef.h>
	31	#endif
	32
	33	#include <stdio.h>
	34	#if HAVE_STRING_H
	35	# include <string.h>
	36	#else
	37	# include <strings.h>
	38	#endif
	39	#if HAVE_STDLIB_H
	40	# include <stdlib.h>
	41	#endif
	42
	43	#if defined _WIN32 \|\| defined __WIN32__
	44	# undef WIN32 /* avoid warning on mingw32 */
	45	# define WIN32
	46	#endif
	47
	48	#if defined __EMX__
	49	/* Assume EMX program runs on OS/2, even if compiled under DOS. */
	50	# define OS2
	51	#endif
	52
	53	#if !defined WIN32
	54	# if HAVE_LANGINFO_CODESET
	55	# include <langinfo.h>
	56	# else
	57	# if HAVE_SETLOCALE
	58	# include <locale.h>
	59	# endif
	60	# endif
	61	#elif defined WIN32
	62	# define WIN32_LEAN_AND_MEAN
	63	# include <windows.h>
	64	#endif
	65	#if defined OS2
	66	# define INCL_DOS
	67	# include <os2.h>
	68	#endif
	69
b0cacab0 TT	70	#if ENABLE_RELOCATABLE
	71	# include "relocatable.h"
	72	#else
	73	# define relocate(pathname) (pathname)
	74	#endif
	75
a04eba3f TT	76	#if defined _WIN32 \|\| defined __WIN32__ \|\| defined __EMX__ \|\| defined __DJGPP__
	77	/* Win32, OS/2, DOS */
	78	# define ISSLASH(C) ((C) == '/' \|\| (C) == '\\')
	79	#endif
	80
	81	#ifndef DIRECTORY_SEPARATOR
	82	# define DIRECTORY_SEPARATOR '/'
	83	#endif
	84
	85	#ifndef ISSLASH
	86	# define ISSLASH(C) ((C) == DIRECTORY_SEPARATOR)
	87	#endif
	88
b0cacab0	89	#if HAVE_DECL_GETC_UNLOCKED
a04eba3f TT	90	# undef getc
	91	# define getc getc_unlocked
	92	#endif
	93
a04eba3f TT	94	/* The following static variable is declared 'volatile' to avoid a
	95	possible multithread problem in the function get_charset_aliases. If we
	96	are running in a threaded environment, and if two threads initialize
	97	'charset_aliases' simultaneously, both will produce the same value,
	98	and everything will be ok if the two assignments to 'charset_aliases'
	99	are atomic. But I don't know what will happen if the two assignments mix. */
	100	#if __STDC__ != 1
	101	# define volatile /* empty */
	102	#endif
	103	/* Pointer to the contents of the charset.alias file, if it has already been
	104	read, else NULL. Its format is:
	105	ALIAS_1 '\0' CANONICAL_1 '\0' ... ALIAS_n '\0' CANONICAL_n '\0' '\0' */
	106	static const char * volatile charset_aliases;
	107
	108	/* Return a pointer to the contents of the charset.alias file. */
	109	static const char *
	110	get_charset_aliases ()
	111	{
	112	const char *cp;
	113
	114	cp = charset_aliases;
	115	if (cp == NULL)
	116	{
b0cacab0	117	#if !(defined VMS \|\| defined WIN32)
a04eba3f	118	FILE *fp;
b0cacab0	119	const char *dir = relocate (LIBDIR);
a04eba3f TT	120	const char *base = "charset.alias";
	121	char *file_name;
	122
	123	/* Concatenate dir and base into freshly allocated file_name. */
	124	{
	125	size_t dir_len = strlen (dir);
	126	size_t base_len = strlen (base);
	127	int add_slash = (dir_len > 0 && !ISSLASH (dir[dir_len - 1]));
	128	file_name = (char *) malloc (dir_len + add_slash + base_len + 1);
	129	if (file_name != NULL)
	130	{
	131	memcpy (file_name, dir, dir_len);
	132	if (add_slash)
	133	file_name[dir_len] = DIRECTORY_SEPARATOR;
	134	memcpy (file_name + dir_len + add_slash, base, base_len + 1);
	135	}
	136	}
	137
	138	if (file_name == NULL \|\| (fp = fopen (file_name, "r")) == NULL)
	139	/* Out of memory or file not found, treat it as empty. */
	140	cp = "";
	141	else
	142	{
	143	/* Parse the file's contents. */
	144	int c;
	145	char buf1[50+1];
	146	char buf2[50+1];
	147	char *res_ptr = NULL;
	148	size_t res_size = 0;
	149	size_t l1, l2;
	150
	151	for (;;)
	152	{
	153	c = getc (fp);
	154	if (c == EOF)
	155	break;
	156	if (c == '\n' \|\| c == ' ' \|\| c == '\t')
	157	continue;
	158	if (c == '#')
	159	{
	160	/* Skip comment, to end of line. */
	161	do
	162	c = getc (fp);
	163	while (!(c == EOF \|\| c == '\n'));
	164	if (c == EOF)
	165	break;
	166	continue;
	167	}
	168	ungetc (c, fp);
	169	if (fscanf (fp, "%50s %50s", buf1, buf2) < 2)
	170	break;
	171	l1 = strlen (buf1);
	172	l2 = strlen (buf2);
	173	if (res_size == 0)
	174	{
	175	res_size = l1 + 1 + l2 + 1;
	176	res_ptr = (char *) malloc (res_size + 1);
	177	}
	178	else
	179	{
	180	res_size += l1 + 1 + l2 + 1;
	181	res_ptr = (char *) realloc (res_ptr, res_size + 1);
	182	}
	183	if (res_ptr == NULL)
184	{
185	/* Out of memory. */
186	res_size = 0;
187	break;
188	}
189	strcpy (res_ptr + res_size - (l2 + 1) - (l1 + 1), buf1);
190	strcpy (res_ptr + res_size - (l2 + 1), buf2);
191	}
192	fclose (fp);
193	if (res_size == 0)
194	cp = "";
195	else
196	{
197	*(res_ptr + res_size) = '\0';
198	cp = res_ptr;
199	}
200	}
201
45e338f5	202	free (file_name);
a04eba3f TT	203
	204	#else
	205
b0cacab0 TT	206	# if defined VMS
	207	/* To avoid the troubles of an extra file charset.alias_vms in the
	208	sources of many GNU packages, simply inline the aliases here. */
	209	/* The list of encodings is taken from the OpenVMS 7.3-1 documentation
	210	"Compaq C Run-Time Library Reference Manual for OpenVMS systems"
	211	section 10.7 "Handling Different Character Sets". */
	212	cp = "ISO8859-1" "\0" "ISO-8859-1" "\0"
	213	"ISO8859-2" "\0" "ISO-8859-2" "\0"
	214	"ISO8859-5" "\0" "ISO-8859-5" "\0"
	215	"ISO8859-7" "\0" "ISO-8859-7" "\0"
	216	"ISO8859-8" "\0" "ISO-8859-8" "\0"
	217	"ISO8859-9" "\0" "ISO-8859-9" "\0"
	218	/* Japanese */
	219	"eucJP" "\0" "EUC-JP" "\0"
	220	"SJIS" "\0" "SHIFT_JIS" "\0"
	221	"DECKANJI" "\0" "DEC-KANJI" "\0"
	222	"SDECKANJI" "\0" "EUC-JP" "\0"
	223	/* Chinese */
	224	"eucTW" "\0" "EUC-TW" "\0"
	225	"DECHANYU" "\0" "DEC-HANYU" "\0"
	226	"DECHANZI" "\0" "GB2312" "\0"
	227	/* Korean */
	228	"DECKOREAN" "\0" "EUC-KR" "\0";
	229	# endif
	230
	231	# if defined WIN32
a04eba3f TT	232	/* To avoid the troubles of installing a separate file in the same
	233	directory as the DLL and of retrieving the DLL's directory at
	234	runtime, simply inline the aliases here. */
	235
a04eba3f TT	236	cp = "CP936" "\0" "GBK" "\0"
	237	"CP1361" "\0" "JOHAB" "\0"
	238	"CP20127" "\0" "ASCII" "\0"
	239	"CP20866" "\0" "KOI8-R" "\0"
	240	"CP21866" "\0" "KOI8-RU" "\0"
	241	"CP28591" "\0" "ISO-8859-1" "\0"
	242	"CP28592" "\0" "ISO-8859-2" "\0"
	243	"CP28593" "\0" "ISO-8859-3" "\0"
	244	"CP28594" "\0" "ISO-8859-4" "\0"
	245	"CP28595" "\0" "ISO-8859-5" "\0"
	246	"CP28596" "\0" "ISO-8859-6" "\0"
	247	"CP28597" "\0" "ISO-8859-7" "\0"
	248	"CP28598" "\0" "ISO-8859-8" "\0"
	249	"CP28599" "\0" "ISO-8859-9" "\0"
	250	"CP28605" "\0" "ISO-8859-15" "\0";
	251	# endif
	252	#endif
	253
	254	charset_aliases = cp;
	255	}
	256
	257	return cp;
	258	}
	259
	260	/* Determine the current locale's character encoding, and canonicalize it
	261	into one of the canonical names listed in config.charset.
	262	The result must not be freed; it is statically allocated.
	263	If the canonical name cannot be determined, the result is a non-canonical
	264	name. */
	265
	266	#ifdef STATIC
	267	STATIC
	268	#endif
	269	const char *
	270	locale_charset ()
	271	{
	272	const char *codeset;
	273	const char *aliases;
	274
	275	#if !(defined WIN32 \|\| defined OS2)
	276
	277	# if HAVE_LANGINFO_CODESET
	278
	279	/* Most systems support nl_langinfo (CODESET) nowadays. */
	280	codeset = nl_langinfo (CODESET);
	281
	282	# else
	283
	284	/* On old systems which lack it, use setlocale or getenv. */
	285	const char *locale = NULL;
	286
	287	/* But most old systems don't have a complete set of locales. Some
	288	(like SunOS 4 or DJGPP) have only the C locale. Therefore we don't
	289	use setlocale here; it would return "C" when it doesn't support the
	290	locale name the user has set. */
	291	# if HAVE_SETLOCALE && 0
	292	locale = setlocale (LC_CTYPE, NULL);
	293	# endif
	294	if (locale == NULL \|\| locale[0] == '\0')
	295	{
	296	locale = getenv ("LC_ALL");
	297	if (locale == NULL \|\| locale[0] == '\0')
	298	{
	299	locale = getenv ("LC_CTYPE");
300	if (locale == NULL \|\| locale[0] == '\0')
301	locale = getenv ("LANG");
302	}
303	}
304
305	/* On some old systems, one used to set locale = "iso8859_1". On others,
306	you set it to "language_COUNTRY.charset". In any case, we resolve it
307	through the charset.alias file. */
308	codeset = locale;
309
310	# endif
311
312	#elif defined WIN32
313
314	static char buf[2 + 10 + 1];
315
316	/* Woe32 has a function returning the locale's codepage as a number. */
317	sprintf (buf, "CP%u", GetACP ());
318	codeset = buf;
319
320	#elif defined OS2
321
322	const char *locale;
323	static char buf[2 + 10 + 1];
324	ULONG cp[3];
325	ULONG cplen;
326
327	/* Allow user to override the codeset, as set in the operating system,
328	with standard language environment variables. */
329	locale = getenv ("LC_ALL");
330	if (locale == NULL \|\| locale[0] == '\0')
331	{
332	locale = getenv ("LC_CTYPE");
333	if (locale == NULL \|\| locale[0] == '\0')
334	locale = getenv ("LANG");
335	}
336	if (locale != NULL && locale[0] != '\0')
337	{
338	/* If the locale name contains an encoding after the dot, return it. */
339	const char *dot = strchr (locale, '.');
340
341	if (dot != NULL)
342	{
343	const char *modifier;
344
345	dot++;
346	/* Look for the possible @... trailer and remove it, if any. */
347	modifier = strchr (dot, '@');
348	if (modifier == NULL)
349	return dot;
350	if (modifier - dot < sizeof (buf))
351	{
352	memcpy (buf, dot, modifier - dot);
353	buf [modifier - dot] = '\0';
354	return buf;
355	}
356	}
357
358	/* Resolve through the charset.alias file. */
359	codeset = locale;
360	}
361	else
362	{
363	/* OS/2 has a function returning the locale's codepage as a number. */
364	if (DosQueryCp (sizeof (cp), cp, &cplen))
365	codeset = "";
366	else
367	{
368	sprintf (buf, "CP%u", cp[0]);
369	codeset = buf;
370	}
371	}
372
373	#endif
374
375	if (codeset == NULL)
376	/* The canonical name cannot be determined. */
377	codeset = "";
378
379	/* Resolve alias. */
380	for (aliases = get_charset_aliases ();
381	*aliases != '\0';
382	aliases += strlen (aliases) + 1, aliases += strlen (aliases) + 1)
383	if (strcmp (codeset, aliases) == 0
384	\|\| (aliases[0] == '*' && aliases[1] == '\0'))
385	{
386	codeset = aliases + strlen (aliases) + 1;
387	break;
388	}
389
390	/* Don't return an empty string. GNU libc and GNU libiconv interpret
391	the empty string as denoting "the locale's character encoding",
392	thus GNU libiconv would call this function a second time. */
393	if (codeset[0] == '\0')
394	codeset = "ASCII";
395
396	return codeset;
397	}