1/* Determine a canonical name for the current locale's character encoding.
2
3   Copyright (C) 2000-2004 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 __CYGWIN__ || defined __EMX__ || defined __DJGPP__
77  /* Win32, Cygwin, 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;
120      const char *base = "charset.alias";
121      char *file_name;
122
123      /* Make it possible to override the charset.alias location.  This is
124	 necessary for running the testsuite before "make install".  */
125      dir = getenv ("CHARSETALIASDIR");
126      if (dir == NULL || dir[0] == '\0')
127	dir = relocate (LIBDIR);
128
129      /* Concatenate dir and base into freshly allocated file_name.  */
130      {
131	size_t dir_len = strlen (dir);
132	size_t base_len = strlen (base);
133	int add_slash = (dir_len > 0 && !ISSLASH (dir[dir_len - 1]));
134	file_name = (char *) malloc (dir_len + add_slash + base_len + 1);
135	if (file_name != NULL)
136	  {
137	    memcpy (file_name, dir, dir_len);
138	    if (add_slash)
139	      file_name[dir_len] = DIRECTORY_SEPARATOR;
140	    memcpy (file_name + dir_len + add_slash, base, base_len + 1);
141	  }
142      }
143
144      if (file_name == NULL || (fp = fopen (file_name, "r")) == NULL)
145	/* Out of memory or file not found, treat it as empty.  */
146	cp = "";
147      else
148	{
149	  /* Parse the file's contents.  */
150	  char *res_ptr = NULL;
151	  size_t res_size = 0;
152
153	  for (;;)
154	    {
155	      int c;
156	      char buf1[50+1];
157	      char buf2[50+1];
158	      size_t l1, l2;
159	      char *old_res_ptr;
160
161	      c = getc (fp);
162	      if (c == EOF)
163		break;
164	      if (c == '\n' || c == ' ' || c == '\t')
165		continue;
166	      if (c == '#')
167		{
168		  /* Skip comment, to end of line.  */
169		  do
170		    c = getc (fp);
171		  while (!(c == EOF || c == '\n'));
172		  if (c == EOF)
173		    break;
174		  continue;
175		}
176	      ungetc (c, fp);
177	      if (fscanf (fp, "%50s %50s", buf1, buf2) < 2)
178		break;
179	      l1 = strlen (buf1);
180	      l2 = strlen (buf2);
181	      old_res_ptr = res_ptr;
182	      if (res_size == 0)
183		{
184		  res_size = l1 + 1 + l2 + 1;
185		  res_ptr = (char *) malloc (res_size + 1);
186		}
187	      else
188		{
189		  res_size += l1 + 1 + l2 + 1;
190		  res_ptr = (char *) realloc (res_ptr, res_size + 1);
191		}
192	      if (res_ptr == NULL)
193		{
194		  /* Out of memory. */
195		  res_size = 0;
196		  if (old_res_ptr != NULL)
197		    free (old_res_ptr);
198		  break;
199		}
200	      strcpy (res_ptr + res_size - (l2 + 1) - (l1 + 1), buf1);
201	      strcpy (res_ptr + res_size - (l2 + 1), buf2);
202	    }
203	  fclose (fp);
204	  if (res_size == 0)
205	    cp = "";
206	  else
207	    {
208	      *(res_ptr + res_size) = '\0';
209	      cp = res_ptr;
210	    }
211	}
212
213      if (file_name != NULL)
214	free (file_name);
215
216#else
217
218# if defined VMS
219      /* To avoid the troubles of an extra file charset.alias_vms in the
220	 sources of many GNU packages, simply inline the aliases here.  */
221      /* The list of encodings is taken from the OpenVMS 7.3-1 documentation
222	 "Compaq C Run-Time Library Reference Manual for OpenVMS systems"
223	 section 10.7 "Handling Different Character Sets".  */
224      cp = "ISO8859-1" "\0" "ISO-8859-1" "\0"
225	   "ISO8859-2" "\0" "ISO-8859-2" "\0"
226	   "ISO8859-5" "\0" "ISO-8859-5" "\0"
227	   "ISO8859-7" "\0" "ISO-8859-7" "\0"
228	   "ISO8859-8" "\0" "ISO-8859-8" "\0"
229	   "ISO8859-9" "\0" "ISO-8859-9" "\0"
230	   /* Japanese */
231	   "eucJP" "\0" "EUC-JP" "\0"
232	   "SJIS" "\0" "SHIFT_JIS" "\0"
233	   "DECKANJI" "\0" "DEC-KANJI" "\0"
234	   "SDECKANJI" "\0" "EUC-JP" "\0"
235	   /* Chinese */
236	   "eucTW" "\0" "EUC-TW" "\0"
237	   "DECHANYU" "\0" "DEC-HANYU" "\0"
238	   "DECHANZI" "\0" "GB2312" "\0"
239	   /* Korean */
240	   "DECKOREAN" "\0" "EUC-KR" "\0";
241# endif
242
243# if defined WIN32
244      /* To avoid the troubles of installing a separate file in the same
245	 directory as the DLL and of retrieving the DLL's directory at
246	 runtime, simply inline the aliases here.  */
247
248      cp = "CP936" "\0" "GBK" "\0"
249	   "CP1361" "\0" "JOHAB" "\0"
250	   "CP20127" "\0" "ASCII" "\0"
251	   "CP20866" "\0" "KOI8-R" "\0"
252	   "CP21866" "\0" "KOI8-RU" "\0"
253	   "CP28591" "\0" "ISO-8859-1" "\0"
254	   "CP28592" "\0" "ISO-8859-2" "\0"
255	   "CP28593" "\0" "ISO-8859-3" "\0"
256	   "CP28594" "\0" "ISO-8859-4" "\0"
257	   "CP28595" "\0" "ISO-8859-5" "\0"
258	   "CP28596" "\0" "ISO-8859-6" "\0"
259	   "CP28597" "\0" "ISO-8859-7" "\0"
260	   "CP28598" "\0" "ISO-8859-8" "\0"
261	   "CP28599" "\0" "ISO-8859-9" "\0"
262	   "CP28605" "\0" "ISO-8859-15" "\0";
263# endif
264#endif
265
266      charset_aliases = cp;
267    }
268
269  return cp;
270}
271
272/* Determine the current locale's character encoding, and canonicalize it
273   into one of the canonical names listed in config.charset.
274   The result must not be freed; it is statically allocated.
275   If the canonical name cannot be determined, the result is a non-canonical
276   name.  */
277
278#ifdef STATIC
279STATIC
280#endif
281const char *
282locale_charset ()
283{
284  const char *codeset;
285  const char *aliases;
286
287#if !(defined WIN32 || defined OS2)
288
289# if HAVE_LANGINFO_CODESET
290
291  /* Most systems support nl_langinfo (CODESET) nowadays.  */
292  codeset = nl_langinfo (CODESET);
293
294# else
295
296  /* On old systems which lack it, use setlocale or getenv.  */
297  const char *locale = NULL;
298
299  /* But most old systems don't have a complete set of locales.  Some
300     (like SunOS 4 or DJGPP) have only the C locale.  Therefore we don't
301     use setlocale here; it would return "C" when it doesn't support the
302     locale name the user has set.  */
303#  if HAVE_SETLOCALE && 0
304  locale = setlocale (LC_CTYPE, NULL);
305#  endif
306  if (locale == NULL || locale[0] == '\0')
307    {
308      locale = getenv ("LC_ALL");
309      if (locale == NULL || locale[0] == '\0')
310	{
311	  locale = getenv ("LC_CTYPE");
312	  if (locale == NULL || locale[0] == '\0')
313	    locale = getenv ("LANG");
314	}
315    }
316
317  /* On some old systems, one used to set locale = "iso8859_1". On others,
318     you set it to "language_COUNTRY.charset". In any case, we resolve it
319     through the charset.alias file.  */
320  codeset = locale;
321
322# endif
323
324#elif defined WIN32
325
326  static char buf[2 + 10 + 1];
327
328  /* Woe32 has a function returning the locale's codepage as a number.  */
329  sprintf (buf, "CP%u", GetACP ());
330  codeset = buf;
331
332#elif defined OS2
333
334  const char *locale;
335  static char buf[2 + 10 + 1];
336  ULONG cp[3];
337  ULONG cplen;
338
339  /* Allow user to override the codeset, as set in the operating system,
340     with standard language environment variables.  */
341  locale = getenv ("LC_ALL");
342  if (locale == NULL || locale[0] == '\0')
343    {
344      locale = getenv ("LC_CTYPE");
345      if (locale == NULL || locale[0] == '\0')
346	locale = getenv ("LANG");
347    }
348  if (locale != NULL && locale[0] != '\0')
349    {
350      /* If the locale name contains an encoding after the dot, return it.  */
351      const char *dot = strchr (locale, '.');
352
353      if (dot != NULL)
354	{
355	  const char *modifier;
356
357	  dot++;
358	  /* Look for the possible @... trailer and remove it, if any.  */
359	  modifier = strchr (dot, '@');
360	  if (modifier == NULL)
361	    return dot;
362	  if (modifier - dot < sizeof (buf))
363	    {
364	      memcpy (buf, dot, modifier - dot);
365	      buf [modifier - dot] = '\0';
366	      return buf;
367	    }
368	}
369
370      /* Resolve through the charset.alias file.  */
371      codeset = locale;
372    }
373  else
374    {
375      /* OS/2 has a function returning the locale's codepage as a number.  */
376      if (DosQueryCp (sizeof (cp), cp, &cplen))
377	codeset = "";
378      else
379	{
380	  sprintf (buf, "CP%u", cp[0]);
381	  codeset = buf;
382	}
383    }
384
385#endif
386
387  if (codeset == NULL)
388    /* The canonical name cannot be determined.  */
389    codeset = "";
390
391  /* Resolve alias. */
392  for (aliases = get_charset_aliases ();
393       *aliases != '\0';
394       aliases += strlen (aliases) + 1, aliases += strlen (aliases) + 1)
395    if (strcmp (codeset, aliases) == 0
396	|| (aliases[0] == '*' && aliases[1] == '\0'))
397      {
398	codeset = aliases + strlen (aliases) + 1;
399	break;
400      }
401
402  /* Don't return an empty string.  GNU libc and GNU libiconv interpret
403     the empty string as denoting "the locale's character encoding",
404     thus GNU libiconv would call this function a second time.  */
405  if (codeset[0] == '\0')
406    codeset = "ASCII";
407
408  return codeset;
409}
410