1 /* Determine a canonical name for the current locale's character encoding.
2
3 Copyright (C) 2000-2002 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 <haible@clisp.cons.org>. */
21
22 #ifdef HAVE_CONFIG_H
23 # include <config.h>
24 #endif
25
26 #if HAVE_STDDEF_H
27 # include <stddef.h>
28 #endif
29
30 #include <stdio.h>
31 #if HAVE_STRING_H
32 # include <string.h>
33 #else
34 # include <strings.h>
35 #endif
36 #if HAVE_STDLIB_H
37 # include <stdlib.h>
38 #endif
39
40 #if defined _WIN32 || defined __WIN32__
41 # undef WIN32 /* avoid warning on mingw32 */
42 # define WIN32
43 #endif
44
45 #if defined __EMX__
46 /* Assume EMX program runs on OS/2, even if compiled under DOS. */
47 # define OS2
48 #endif
49
50 #if !defined WIN32
51 # if HAVE_LANGINFO_CODESET
52 # include <langinfo.h>
53 # else
54 # if HAVE_SETLOCALE
55 # include <locale.h>
56 # endif
57 # endif
58 #elif defined WIN32
59 # define WIN32_LEAN_AND_MEAN
60 # include <windows.h>
61 #endif
62 #if defined OS2
63 # define INCL_DOS
64 # include <os2.h>
65 #endif
66
67 #if defined _WIN32 || defined __WIN32__ || defined __EMX__ || defined __DJGPP__
68 /* Win32, OS/2, DOS */
69 # define ISSLASH(C) ((C) == '/' || (C) == '\\')
70 #endif
71
72 #ifndef DIRECTORY_SEPARATOR
73 # define DIRECTORY_SEPARATOR '/'
74 #endif
75
76 #ifndef ISSLASH
77 # define ISSLASH(C) ((C) == DIRECTORY_SEPARATOR)
78 #endif
79
80 #ifdef HAVE_GETC_UNLOCKED
81 # undef getc
82 # define getc getc_unlocked
83 #endif
84
85 /* The following static variable is declared 'volatile' to avoid a
86 possible multithread problem in the function get_charset_aliases. If we
87 are running in a threaded environment, and if two threads initialize
88 'charset_aliases' simultaneously, both will produce the same value,
89 and everything will be ok if the two assignments to 'charset_aliases'
90 are atomic. But I don't know what will happen if the two assignments mix. */
91 #if __STDC__ != 1
92 # define volatile /* empty */
93 #endif
94 /* Pointer to the contents of the charset.alias file, if it has already been
95 read, else NULL. Its format is:
96 ALIAS_1 '\0' CANONICAL_1 '\0' ... ALIAS_n '\0' CANONICAL_n '\0' '\0' */
97 static const char * volatile charset_aliases;
98
99 /* Return a pointer to the contents of the charset.alias file. */
100 static const char *
get_charset_aliases()101 get_charset_aliases ()
102 {
103 const char *cp;
104
105 cp = charset_aliases;
106 if (cp == NULL)
107 {
108 #if !defined WIN32
109 FILE *fp;
110 const char *dir = LIBDIR;
111 const char *base = "charset.alias";
112 char *file_name;
113
114 /* Concatenate dir and base into freshly allocated file_name. */
115 {
116 size_t dir_len = strlen (dir);
117 size_t base_len = strlen (base);
118 int add_slash = (dir_len > 0 && !ISSLASH (dir[dir_len - 1]));
119 file_name = (char *) malloc (dir_len + add_slash + base_len + 1);
120 if (file_name != NULL)
121 {
122 memcpy (file_name, dir, dir_len);
123 if (add_slash)
124 file_name[dir_len] = DIRECTORY_SEPARATOR;
125 memcpy (file_name + dir_len + add_slash, base, base_len + 1);
126 }
127 }
128
129 if (file_name == NULL || (fp = fopen (file_name, "r")) == NULL)
130 /* Out of memory or file not found, treat it as empty. */
131 cp = "";
132 else
133 {
134 /* Parse the file's contents. */
135 int c;
136 char buf1[50+1];
137 char buf2[50+1];
138 char *res_ptr = NULL;
139 size_t res_size = 0;
140 size_t l1, l2;
141
142 for (;;)
143 {
144 c = getc (fp);
145 if (c == EOF)
146 break;
147 if (c == '\n' || c == ' ' || c == '\t')
148 continue;
149 if (c == '#')
150 {
151 /* Skip comment, to end of line. */
152 do
153 c = getc (fp);
154 while (!(c == EOF || c == '\n'));
155 if (c == EOF)
156 break;
157 continue;
158 }
159 ungetc (c, fp);
160 if (fscanf (fp, "%50s %50s", buf1, buf2) < 2)
161 break;
162 l1 = strlen (buf1);
163 l2 = strlen (buf2);
164 if (res_size == 0)
165 {
166 res_size = l1 + 1 + l2 + 1;
167 res_ptr = (char *) malloc (res_size + 1);
168 }
169 else
170 {
171 res_size += l1 + 1 + l2 + 1;
172 res_ptr = (char *) realloc (res_ptr, res_size + 1);
173 }
174 if (res_ptr == NULL)
175 {
176 /* Out of memory. */
177 res_size = 0;
178 break;
179 }
180 strcpy (res_ptr + res_size - (l2 + 1) - (l1 + 1), buf1);
181 strcpy (res_ptr + res_size - (l2 + 1), buf2);
182 }
183 fclose (fp);
184 if (res_size == 0)
185 cp = "";
186 else
187 {
188 *(res_ptr + res_size) = '\0';
189 cp = res_ptr;
190 }
191 }
192
193 if (file_name != NULL)
194 free (file_name);
195
196 #else
197
198 /* To avoid the troubles of installing a separate file in the same
199 directory as the DLL and of retrieving the DLL's directory at
200 runtime, simply inline the aliases here. */
201
202 # if defined WIN32
203 cp = "CP936" "\0" "GBK" "\0"
204 "CP1361" "\0" "JOHAB" "\0";
205 # endif
206 #endif
207
208 charset_aliases = cp;
209 }
210
211 return cp;
212 }
213
214 /* Determine the current locale's character encoding, and canonicalize it
215 into one of the canonical names listed in config.charset.
216 The result must not be freed; it is statically allocated.
217 If the canonical name cannot be determined, the result is a non-canonical
218 name. */
219
220 #ifdef STATIC
221 STATIC
222 #endif
223 const char *
locale_charset()224 locale_charset ()
225 {
226 const char *codeset;
227 const char *aliases;
228
229 #if !(defined WIN32 || defined OS2)
230
231 # if HAVE_LANGINFO_CODESET
232
233 /* Most systems support nl_langinfo (CODESET) nowadays. */
234 codeset = nl_langinfo (CODESET);
235
236 # else
237
238 /* On old systems which lack it, use setlocale or getenv. */
239 const char *locale = NULL;
240
241 /* But most old systems don't have a complete set of locales. Some
242 (like SunOS 4 or DJGPP) have only the C locale. Therefore we don't
243 use setlocale here; it would return "C" when it doesn't support the
244 locale name the user has set. */
245 # if HAVE_SETLOCALE && 0
246 locale = setlocale (LC_CTYPE, NULL);
247 # endif
248 if (locale == NULL || locale[0] == '\0')
249 {
250 locale = getenv ("LC_ALL");
251 if (locale == NULL || locale[0] == '\0')
252 {
253 locale = getenv ("LC_CTYPE");
254 if (locale == NULL || locale[0] == '\0')
255 locale = getenv ("LANG");
256 }
257 }
258
259 /* On some old systems, one used to set locale = "iso8859_1". On others,
260 you set it to "language_COUNTRY.charset". In any case, we resolve it
261 through the charset.alias file. */
262 codeset = locale;
263
264 # endif
265
266 #elif defined WIN32
267
268 static char buf[2 + 10 + 1];
269
270 /* Win32 has a function returning the locale's codepage as a number. */
271 sprintf (buf, "CP%u", GetACP ());
272 codeset = buf;
273
274 #elif defined OS2
275
276 const char *locale;
277 static char buf[2 + 10 + 1];
278 ULONG cp[3];
279 ULONG cplen;
280
281 /* Allow user to override the codeset, as set in the operating system,
282 with standard language environment variables. */
283 locale = getenv ("LC_ALL");
284 if (locale == NULL || locale[0] == '\0')
285 {
286 locale = getenv ("LC_CTYPE");
287 if (locale == NULL || locale[0] == '\0')
288 locale = getenv ("LANG");
289 }
290 if (locale != NULL && locale[0] != '\0')
291 {
292 /* If the locale name contains an encoding after the dot, return it. */
293 const char *dot = strchr (locale, '.');
294
295 if (dot != NULL)
296 {
297 const char *modifier;
298
299 dot++;
300 /* Look for the possible @... trailer and remove it, if any. */
301 modifier = strchr (dot, '@');
302 if (modifier == NULL)
303 return dot;
304 if (modifier - dot < sizeof (buf))
305 {
306 memcpy (buf, dot, modifier - dot);
307 buf [modifier - dot] = '\0';
308 return buf;
309 }
310 }
311
312 /* Resolve through the charset.alias file. */
313 codeset = locale;
314 }
315 else
316 {
317 /* OS/2 has a function returning the locale's codepage as a number. */
318 if (DosQueryCp (sizeof (cp), cp, &cplen))
319 codeset = "";
320 else
321 {
322 sprintf (buf, "CP%u", cp[0]);
323 codeset = buf;
324 }
325 }
326
327 #endif
328
329 if (codeset == NULL)
330 /* The canonical name cannot be determined. */
331 codeset = "";
332
333 /* Resolve alias. */
334 for (aliases = get_charset_aliases ();
335 *aliases != '\0';
336 aliases += strlen (aliases) + 1, aliases += strlen (aliases) + 1)
337 if (strcmp (codeset, aliases) == 0
338 || (aliases[0] == '*' && aliases[1] == '\0'))
339 {
340 codeset = aliases + strlen (aliases) + 1;
341 break;
342 }
343
344 return codeset;
345 }
346