Initial release, version 0.0.0.
[gsasl.git] / src / libcharset / localcharset.c
blobe24d33e58021154c01a9b2fdaf53990a48ad41e3
1 /* Determine a canonical name for the current locale's character encoding.
3 Copyright (C) 2000-2002 Free Software Foundation, Inc.
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.
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.
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. */
20 /* Written by Bruno Haible <bruno@clisp.org>. */
22 #ifdef HAVE_CONFIG_H
23 # include <config.h>
24 #endif
26 #if HAVE_STDDEF_H
27 # include <stddef.h>
28 #endif
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
40 #if defined _WIN32 || defined __WIN32__
41 # undef WIN32 /* avoid warning on mingw32 */
42 # define WIN32
43 #endif
45 #if defined __EMX__
46 /* Assume EMX program runs on OS/2, even if compiled under DOS. */
47 # define OS2
48 #endif
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
67 #if defined _WIN32 || defined __WIN32__ || defined __EMX__ || defined __DJGPP__
68 /* Win32, OS/2, DOS */
69 # define ISSLASH(C) ((C) == '/' || (C) == '\\')
70 #endif
72 #ifndef DIRECTORY_SEPARATOR
73 # define DIRECTORY_SEPARATOR '/'
74 #endif
76 #ifndef ISSLASH
77 # define ISSLASH(C) ((C) == DIRECTORY_SEPARATOR)
78 #endif
80 #ifdef HAVE_GETC_UNLOCKED
81 # undef getc
82 # define getc getc_unlocked
83 #endif
85 #ifdef __cplusplus
86 /* When compiling with "gcc -x c++", produce a function with C linkage. */
87 extern "C" const char * locale_charset (void);
88 #endif
90 /* The following static variable is declared 'volatile' to avoid a
91 possible multithread problem in the function get_charset_aliases. If we
92 are running in a threaded environment, and if two threads initialize
93 'charset_aliases' simultaneously, both will produce the same value,
94 and everything will be ok if the two assignments to 'charset_aliases'
95 are atomic. But I don't know what will happen if the two assignments mix. */
96 #if __STDC__ != 1
97 # define volatile /* empty */
98 #endif
99 /* Pointer to the contents of the charset.alias file, if it has already been
100 read, else NULL. Its format is:
101 ALIAS_1 '\0' CANONICAL_1 '\0' ... ALIAS_n '\0' CANONICAL_n '\0' '\0' */
102 static const char * volatile charset_aliases;
104 /* Return a pointer to the contents of the charset.alias file. */
105 const char *
106 _gsasl_locale_get_charset_aliases ()
108 const char *cp;
110 cp = charset_aliases;
111 if (cp == NULL)
113 #if !defined WIN32
114 FILE *fp;
115 const char *dir = LIBDIR;
116 const char *base = "charset.alias";
117 char *file_name;
119 /* Concatenate dir and base into freshly allocated file_name. */
121 size_t dir_len = strlen (dir);
122 size_t base_len = strlen (base);
123 int add_slash = (dir_len > 0 && !ISSLASH (dir[dir_len - 1]));
124 file_name = (char *) malloc (dir_len + add_slash + base_len + 1);
125 if (file_name != NULL)
127 memcpy (file_name, dir, dir_len);
128 if (add_slash)
129 file_name[dir_len] = DIRECTORY_SEPARATOR;
130 memcpy (file_name + dir_len + add_slash, base, base_len + 1);
134 if (file_name == NULL || (fp = fopen (file_name, "r")) == NULL)
135 /* Out of memory or file not found, treat it as empty. */
136 cp = "";
137 else
139 /* Parse the file's contents. */
140 int c;
141 char buf1[50+1];
142 char buf2[50+1];
143 char *res_ptr = NULL;
144 size_t res_size = 0;
145 size_t l1, l2;
147 for (;;)
149 c = getc (fp);
150 if (c == EOF)
151 break;
152 if (c == '\n' || c == ' ' || c == '\t')
153 continue;
154 if (c == '#')
156 /* Skip comment, to end of line. */
158 c = getc (fp);
159 while (!(c == EOF || c == '\n'));
160 if (c == EOF)
161 break;
162 continue;
164 ungetc (c, fp);
165 if (fscanf (fp, "%50s %50s", buf1, buf2) < 2)
166 break;
167 l1 = strlen (buf1);
168 l2 = strlen (buf2);
169 if (res_size == 0)
171 res_size = l1 + 1 + l2 + 1;
172 res_ptr = (char *) malloc (res_size + 1);
174 else
176 res_size += l1 + 1 + l2 + 1;
177 res_ptr = (char *) realloc (res_ptr, res_size + 1);
179 if (res_ptr == NULL)
181 /* Out of memory. */
182 res_size = 0;
183 break;
185 strcpy (res_ptr + res_size - (l2 + 1) - (l1 + 1), buf1);
186 strcpy (res_ptr + res_size - (l2 + 1), buf2);
188 fclose (fp);
189 if (res_size == 0)
190 cp = "";
191 else
193 *(res_ptr + res_size) = '\0';
194 cp = res_ptr;
198 if (file_name != NULL)
199 free (file_name);
201 #else
203 /* To avoid the troubles of installing a separate file in the same
204 directory as the DLL and of retrieving the DLL's directory at
205 runtime, simply inline the aliases here. */
207 # if defined WIN32
208 cp = "CP936" "\0" "GBK" "\0"
209 "CP1361" "\0" "JOHAB" "\0"
210 "CP20127" "\0" "ASCII" "\0"
211 "CP20866" "\0" "KOI8-R" "\0"
212 "CP21866" "\0" "KOI8-RU" "\0"
213 "CP28591" "\0" "ISO-8859-1" "\0"
214 "CP28592" "\0" "ISO-8859-2" "\0"
215 "CP28593" "\0" "ISO-8859-3" "\0"
216 "CP28594" "\0" "ISO-8859-4" "\0"
217 "CP28595" "\0" "ISO-8859-5" "\0"
218 "CP28596" "\0" "ISO-8859-6" "\0"
219 "CP28597" "\0" "ISO-8859-7" "\0"
220 "CP28598" "\0" "ISO-8859-8" "\0"
221 "CP28599" "\0" "ISO-8859-9" "\0"
222 "CP28605" "\0" "ISO-8859-15" "\0";
223 # endif
224 #endif
226 charset_aliases = cp;
229 return cp;
232 /* Determine the current locale's character encoding, and canonicalize it
233 into one of the canonical names listed in config.charset.
234 The result must not be freed; it is statically allocated.
235 If the canonical name cannot be determined, the result is a non-canonical
236 name. */
238 #ifdef STATIC
239 STATIC
240 #endif
241 const char *
242 _gsasl_locale_charset ()
244 const char *codeset;
245 const char *aliases;
247 #if !(defined WIN32 || defined OS2)
249 # if HAVE_LANGINFO_CODESET
251 /* Most systems support nl_langinfo (CODESET) nowadays. */
252 codeset = nl_langinfo (CODESET);
254 # else
256 /* On old systems which lack it, use setlocale or getenv. */
257 const char *locale = NULL;
259 /* But most old systems don't have a complete set of locales. Some
260 (like SunOS 4 or DJGPP) have only the C locale. Therefore we don't
261 use setlocale here; it would return "C" when it doesn't support the
262 locale name the user has set. */
263 # if HAVE_SETLOCALE && 0
264 locale = setlocale (LC_CTYPE, NULL);
265 # endif
266 if (locale == NULL || locale[0] == '\0')
268 locale = getenv ("LC_ALL");
269 if (locale == NULL || locale[0] == '\0')
271 locale = getenv ("LC_CTYPE");
272 if (locale == NULL || locale[0] == '\0')
273 locale = getenv ("LANG");
277 /* On some old systems, one used to set locale = "iso8859_1". On others,
278 you set it to "language_COUNTRY.charset". In any case, we resolve it
279 through the charset.alias file. */
280 codeset = locale;
282 # endif
284 #elif defined WIN32
286 static char buf[2 + 10 + 1];
288 /* Woe32 has a function returning the locale's codepage as a number. */
289 sprintf (buf, "CP%u", GetACP ());
290 codeset = buf;
292 #elif defined OS2
294 const char *locale;
295 static char buf[2 + 10 + 1];
296 ULONG cp[3];
297 ULONG cplen;
299 /* Allow user to override the codeset, as set in the operating system,
300 with standard language environment variables. */
301 locale = getenv ("LC_ALL");
302 if (locale == NULL || locale[0] == '\0')
304 locale = getenv ("LC_CTYPE");
305 if (locale == NULL || locale[0] == '\0')
306 locale = getenv ("LANG");
308 if (locale != NULL && locale[0] != '\0')
310 /* If the locale name contains an encoding after the dot, return it. */
311 const char *dot = strchr (locale, '.');
313 if (dot != NULL)
315 const char *modifier;
317 dot++;
318 /* Look for the possible @... trailer and remove it, if any. */
319 modifier = strchr (dot, '@');
320 if (modifier == NULL)
321 return dot;
322 if (modifier - dot < sizeof (buf))
324 memcpy (buf, dot, modifier - dot);
325 buf [modifier - dot] = '\0';
326 return buf;
330 /* Resolve through the charset.alias file. */
331 codeset = locale;
333 else
335 /* OS/2 has a function returning the locale's codepage as a number. */
336 if (DosQueryCp (sizeof (cp), cp, &cplen))
337 codeset = "";
338 else
340 sprintf (buf, "CP%u", cp[0]);
341 codeset = buf;
345 #endif
347 if (codeset == NULL)
348 /* The canonical name cannot be determined. */
349 codeset = "";
351 /* Resolve alias. */
352 for (aliases = _gsasl_locale_get_charset_aliases ();
353 *aliases != '\0';
354 aliases += strlen (aliases) + 1, aliases += strlen (aliases) + 1)
355 if (strcmp (codeset, aliases) == 0
356 || (aliases[0] == '*' && aliases[1] == '\0'))
358 codeset = aliases + strlen (aliases) + 1;
359 break;
362 /* Don't return an empty string. GNU libc and GNU libiconv interpret
363 the empty string as denoting "the locale's character encoding",
364 thus GNU libiconv would call this function a second time. */
365 if (codeset[0] == '\0')
366 codeset = "ASCII";
368 return codeset;