1/* Determine a canonical name for the current locale's character encoding.
2
3   Copyright (C) 2000-2003 Free Software Foundation, Inc.
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
17   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
18   USA.  */
19
20/* Written by Bruno Haible <bruno@clisp.org>.  */
21
22#ifdef HAVE_CONFIG_H
23# include <config.h>
24#endif
25
26/* Specification.  */
27#include "localcharset.h"
28
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
70#if ENABLE_RELOCATABLE
71# include "relocatable.h"
72#else
73# define relocate(pathname) (pathname)
74#endif
75
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
89#if HAVE_DECL_GETC_UNLOCKED
90# undef getc
91# define getc getc_unlocked
92#endif
93
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'  */
106static const char * volatile charset_aliases;
107
108/* Return a pointer to the contents of the charset.alias file.  */
109static const char *
110get_charset_aliases ()
111{
112  const char *cp;
113
114  cp = charset_aliases;
115  if (cp == NULL)
116    {
117#if !(defined VMS || defined WIN32)
118      FILE *fp;
119      const char *dir = relocate (LIBDIR);
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
202      free (file_name);
203
204#else
205
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
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
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
267STATIC
268#endif
269const char *
270locale_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}
398