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