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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301,
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 #ifdef HAVE_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' */
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 {
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 if (file_name != NULL)
203 free (file_name);
204
205 #else
206
207 # if defined VMS
208 /* To avoid the troubles of an extra file charset.alias_vms in the
209 sources of many GNU packages, simply inline the aliases here. */
210 /* The list of encodings is taken from the OpenVMS 7.3-1 documentation
211 "Compaq C Run-Time Library Reference Manual for OpenVMS systems"
212 section 10.7 "Handling Different Character Sets". */
213 cp = "ISO8859-1" "\0" "ISO-8859-1" "\0"
214 "ISO8859-2" "\0" "ISO-8859-2" "\0"
215 "ISO8859-5" "\0" "ISO-8859-5" "\0"
216 "ISO8859-7" "\0" "ISO-8859-7" "\0"
217 "ISO8859-8" "\0" "ISO-8859-8" "\0"
218 "ISO8859-9" "\0" "ISO-8859-9" "\0"
219 /* Japanese */
220 "eucJP" "\0" "EUC-JP" "\0"
221 "SJIS" "\0" "SHIFT_JIS" "\0"
222 "DECKANJI" "\0" "DEC-KANJI" "\0"
223 "SDECKANJI" "\0" "EUC-JP" "\0"
224 /* Chinese */
225 "eucTW" "\0" "EUC-TW" "\0"
226 "DECHANYU" "\0" "DEC-HANYU" "\0"
227 "DECHANZI" "\0" "GB2312" "\0"
228 /* Korean */
229 "DECKOREAN" "\0" "EUC-KR" "\0";
230 # endif
231
232 # if defined WIN32
233 /* To avoid the troubles of installing a separate file in the same
234 directory as the DLL and of retrieving the DLL's directory at
235 runtime, simply inline the aliases here. */
236
237 cp = "CP936" "\0" "GBK" "\0"
238 "CP1361" "\0" "JOHAB" "\0"
239 "CP20127" "\0" "ASCII" "\0"
240 "CP20866" "\0" "KOI8-R" "\0"
241 "CP21866" "\0" "KOI8-RU" "\0"
242 "CP28591" "\0" "ISO-8859-1" "\0"
243 "CP28592" "\0" "ISO-8859-2" "\0"
244 "CP28593" "\0" "ISO-8859-3" "\0"
245 "CP28594" "\0" "ISO-8859-4" "\0"
246 "CP28595" "\0" "ISO-8859-5" "\0"
247 "CP28596" "\0" "ISO-8859-6" "\0"
248 "CP28597" "\0" "ISO-8859-7" "\0"
249 "CP28598" "\0" "ISO-8859-8" "\0"
250 "CP28599" "\0" "ISO-8859-9" "\0"
251 "CP28605" "\0" "ISO-8859-15" "\0";
252 # endif
253 #endif
254
255 charset_aliases = cp;
256 }
257
258 return cp;
259 }
260
261 /* Determine the current locale's character encoding, and canonicalize it
262 into one of the canonical names listed in config.charset.
263 The result must not be freed; it is statically allocated.
264 If the canonical name cannot be determined, the result is a non-canonical
265 name. */
266
267 #ifdef STATIC
268 STATIC
269 #endif
270 const char *
271 locale_charset ()
272 {
273 const char *codeset;
274 const char *aliases;
275
276 #if !(defined WIN32 || defined OS2)
277
278 # if HAVE_LANGINFO_CODESET
279
280 /* Most systems support nl_langinfo (CODESET) nowadays. */
281 codeset = nl_langinfo (CODESET);
282
283 # else
284
285 /* On old systems which lack it, use setlocale or getenv. */
286 const char *locale = NULL;
287
288 /* But most old systems don't have a complete set of locales. Some
289 (like SunOS 4 or DJGPP) have only the C locale. Therefore we don't
290 use setlocale here; it would return "C" when it doesn't support the
291 locale name the user has set. */
292 # if HAVE_SETLOCALE && 0
293 locale = setlocale (LC_CTYPE, NULL);
294 # endif
295 if (locale == NULL || locale[0] == '\0')
296 {
297 locale = getenv ("LC_ALL");
298 if (locale == NULL || locale[0] == '\0')
299 {
300 locale = getenv ("LC_CTYPE");
301 if (locale == NULL || locale[0] == '\0')
302 locale = getenv ("LANG");
303 }
304 }
305
306 /* On some old systems, one used to set locale = "iso8859_1". On others,
307 you set it to "language_COUNTRY.charset". In any case, we resolve it
308 through the charset.alias file. */
309 codeset = locale;
310
311 # endif
312
313 #elif defined WIN32
314
315 static char buf[2 + 10 + 1];
316
317 /* Woe32 has a function returning the locale's codepage as a number. */
318 sprintf (buf, "CP%u", GetACP ());
319 codeset = buf;
320
321 #elif defined OS2
322
323 const char *locale;
324 static char buf[2 + 10 + 1];
325 ULONG cp[3];
326 ULONG cplen;
327
328 /* Allow user to override the codeset, as set in the operating system,
329 with standard language environment variables. */
330 locale = getenv ("LC_ALL");
331 if (locale == NULL || locale[0] == '\0')
332 {
333 locale = getenv ("LC_CTYPE");
334 if (locale == NULL || locale[0] == '\0')
335 locale = getenv ("LANG");
336 }
337 if (locale != NULL && locale[0] != '\0')
338 {
339 /* If the locale name contains an encoding after the dot, return it. */
340 const char *dot = strchr (locale, '.');
341
342 if (dot != NULL)
343 {
344 const char *modifier;
345
346 dot++;
347 /* Look for the possible @... trailer and remove it, if any. */
348 modifier = strchr (dot, '@');
349 if (modifier == NULL)
350 return dot;
351 if (modifier - dot < sizeof (buf))
352 {
353 memcpy (buf, dot, modifier - dot);
354 buf [modifier - dot] = '\0';
355 return buf;
356 }
357 }
358
359 /* Resolve through the charset.alias file. */
360 codeset = locale;
361 }
362 else
363 {
364 /* OS/2 has a function returning the locale's codepage as a number. */
365 if (DosQueryCp (sizeof (cp), cp, &cplen))
366 codeset = "";
367 else
368 {
369 sprintf (buf, "CP%u", cp[0]);
370 codeset = buf;
371 }
372 }
373
374 #endif
375
376 if (codeset == NULL)
377 /* The canonical name cannot be determined. */
378 codeset = "";
379
380 /* Resolve alias. */
381 for (aliases = get_charset_aliases ();
382 *aliases != '\0';
383 aliases += strlen (aliases) + 1, aliases += strlen (aliases) + 1)
384 if (strcmp (codeset, aliases) == 0
385 || (aliases[0] == '*' && aliases[1] == '\0'))
386 {
387 codeset = aliases + strlen (aliases) + 1;
388 break;
389 }
390
391 /* Don't return an empty string. GNU libc and GNU libiconv interpret
392 the empty string as denoting "the locale's character encoding",
393 thus GNU libiconv would call this function a second time. */
394 if (codeset[0] == '\0')
395 codeset = "ASCII";
396
397 return codeset;
398 }