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1 /* Determine a canonical name for the current locale's character encoding.
2
3 Copyright (C) 2000-2001 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 <autoconf.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 #ifndef WIN32
46 # if HAVE_LANGINFO_CODESET
47 # include <langinfo.h>
48 # else
49 # if HAVE_SETLOCALE
50 # include <locale.h>
51 # endif
52 # endif
53 #else /* WIN32 */
54 # define WIN32_LEAN_AND_MEAN
55 # include <windows.h>
56 #endif
57
58 #ifndef DIRECTORY_SEPARATOR
59 # define DIRECTORY_SEPARATOR '/'
60 #endif
61
62 #ifndef ISSLASH
63 # define ISSLASH(C) ((C) == DIRECTORY_SEPARATOR)
64 #endif
65
66 /* The following static variable is declared 'volatile' to avoid a
67 possible multithread problem in the function get_charset_aliases. If we
68 are running in a threaded environment, and if two threads initialize
69 'charset_aliases' simultaneously, both will produce the same value,
70 and everything will be ok if the two assignments to 'charset_aliases'
71 are atomic. But I don't know what will happen if the two assignments mix. */
72 #if __STDC__ != 1
73 # define volatile /* empty */
74 #endif
75 /* Pointer to the contents of the charset.alias file, if it has already been
76 read, else NULL. Its format is:
77 ALIAS_1 '\0' CANONICAL_1 '\0' ... ALIAS_n '\0' CANONICAL_n '\0' '\0' */
78 static const char * volatile charset_aliases;
79
80 /* Return a pointer to the contents of the charset.alias file. */
81 static const char *
82 get_charset_aliases (void)
83 {
84 const char *cp;
85
86 cp = charset_aliases;
87 if (cp == NULL)
88 {
89 #ifndef WIN32
90 FILE *fp;
91 const char *dir = LIBDIR;
92 const char *base = "charset.alias";
93 char *file_name;
94
95 /* Concatenate dir and base into freshly allocated file_name. */
96 {
97 size_t dir_len = strlen (dir);
98 size_t base_len = strlen (base);
99 int add_slash = (dir_len > 0 && !ISSLASH (dir[dir_len - 1]));
100 file_name = (char *) malloc (dir_len + add_slash + base_len + 1);
101 if (file_name != NULL)
102 {
103 memcpy (file_name, dir, dir_len);
104 if (add_slash)
105 file_name[dir_len] = DIRECTORY_SEPARATOR;
106 memcpy (file_name + dir_len + add_slash, base, base_len + 1);
107 }
108 }
109
110 if (file_name == NULL || (fp = fopen (file_name, "r")) == NULL)
111 /* Out of memory or file not found, treat it as empty. */
112 cp = "";
113 else
114 {
115 /* Parse the file's contents. */
116 int c;
117 char buf1[50+1];
118 char buf2[50+1];
119 char *res_ptr = NULL;
120 size_t res_size = 0;
121 size_t l1, l2;
122
123 for (;;)
124 {
125 c = getc (fp);
126 if (c == EOF)
127 break;
128 if (c == '\n' || c == ' ' || c == '\t')
129 continue;
130 if (c == '#')
131 {
132 /* Skip comment, to end of line. */
133 do
134 c = getc (fp);
135 while (!(c == EOF || c == '\n'));
136 if (c == EOF)
137 break;
138 continue;
139 }
140 ungetc (c, fp);
141 if (fscanf(fp, "%50s %50s", buf1, buf2) < 2)
142 break;
143 l1 = strlen (buf1);
144 l2 = strlen (buf2);
145 if (res_size == 0)
146 {
147 res_size = l1 + 1 + l2 + 1;
148 res_ptr = malloc (res_size + 1);
149 }
150 else
151 {
152 res_size += l1 + 1 + l2 + 1;
153 res_ptr = realloc (res_ptr, res_size + 1);
154 }
155 if (res_ptr == NULL)
156 {
157 /* Out of memory. */
158 res_size = 0;
159 break;
160 }
161 strcpy (res_ptr + res_size - (l2 + 1) - (l1 + 1), buf1);
162 strcpy (res_ptr + res_size - (l2 + 1), buf2);
163 }
164 fclose (fp);
165 if (res_size == 0)
166 cp = "";
167 else
168 {
169 *(res_ptr + res_size) = '\0';
170 cp = res_ptr;
171 }
172 }
173
174 if (file_name != NULL)
175 free (file_name);
176
177 #else /* WIN32 */
178
179 /* To avoid the troubles of installing a separate file in the same
180 directory as the DLL and of retrieving the DLL's directory at
181 runtime, simply inline the aliases here. */
182
183 cp = "CP936" "\0" "GBK" "\0"
184 "CP1361" "\0" "JOHAB" "\0";
185 #endif
186
187 charset_aliases = cp;
188 }
189
190 return cp;
191 }
192
193 /* Determine the current locale's character encoding, and canonicalize it
194 into one of the canonical names listed in config.charset.
195 The result must not be freed; it is statically allocated.
196 If the canonical name cannot be determined, the result is a non-canonical
197 name. */
198
199 #ifdef STATIC
200 STATIC
201 #endif
202 const char *
203 locale_charset (void)
204 {
205 const char *codeset;
206 const char *aliases;
207
208 #ifndef WIN32
209
210 # if HAVE_LANGINFO_CODESET
211
212 /* Most systems support nl_langinfo (CODESET) nowadays. */
213 codeset = nl_langinfo (CODESET);
214
215 # else
216
217 /* On old systems which lack it, use setlocale or getenv. */
218 const char *locale = NULL;
219
220 /* But most old systems don't have a complete set of locales. Some
221 (like SunOS 4 or DJGPP) have only the C locale. Therefore we don't
222 use setlocale here; it would return "C" when it doesn't support the
223 locale name the user has set. */
224 # if HAVE_SETLOCALE && 0
225 locale = setlocale (LC_CTYPE, NULL);
226 # endif
227 if (locale == NULL || locale[0] == '\0')
228 {
229 locale = getenv ("LC_ALL");
230 if (locale == NULL || locale[0] == '\0')
231 {
232 locale = getenv ("LC_CTYPE");
233 if (locale == NULL || locale[0] == '\0')
234 locale = getenv ("LANG");
235 }
236 }
237
238 /* On some old systems, one used to set locale = "iso8859_1". On others,
239 you set it to "language_COUNTRY.charset". In any case, we resolve it
240 through the charset.alias file. */
241 codeset = locale;
242
243 # endif
244
245 #else /* WIN32 */
246
247 static char buf[2 + 10 + 1];
248
249 /* Win32 has a function returning the locale's codepage as a number. */
250 sprintf (buf, "CP%u", GetACP ());
251 codeset = buf;
252
253 #endif
254
255 if (codeset == NULL)
256 /* The canonical name cannot be determined. */
257 codeset = "";
258
259 /* Resolve alias. */
260 for (aliases = get_charset_aliases ();
261 *aliases != '\0';
262 aliases += strlen (aliases) + 1, aliases += strlen (aliases) + 1)
263 if (strcmp (codeset, aliases) == 0
264 || (aliases[0] == '*' && aliases[1] == '\0'))
265 {
266 codeset = aliases + strlen (aliases) + 1;
267 break;
268 }
269
270 return codeset;
271 }