localcharset.c revision 1.1.1.1 
1/*	$NetBSD: localcharset.c,v 1.1.1.1 2016/01/10 21:36:18 christos Exp $	*/
2
3/* Determine a canonical name for the current locale's character encoding.
4
5   Copyright (C) 2000-2002 Free Software Foundation, Inc.
6
7   This program is free software; you can redistribute it and/or modify it
8   under the terms of the GNU Library General Public License as published
9   by the Free Software Foundation; either version 2, or (at your option)
10   any later version.
11
12   This program is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15   Library General Public License for more details.
16
17   You should have received a copy of the GNU Library General Public
18   License along with this program; if not, write to the Free Software
19   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
20   USA.  */
21
22/* Written by Bruno Haible <haible@clisp.cons.org>.  */
23
24#ifdef HAVE_CONFIG_H
25# include <config.h>
26#endif
27
28#if HAVE_STDDEF_H
29# include <stddef.h>
30#endif
31
32#include <stdio.h>
33#if HAVE_STRING_H
34# include <string.h>
35#else
36# include <strings.h>
37#endif
38#if HAVE_STDLIB_H
39# include <stdlib.h>
40#endif
41
42#if defined _WIN32 || defined __WIN32__
43# undef WIN32   /* avoid warning on mingw32 */
44# define WIN32
45#endif
46
47#if defined __EMX__
48/* Assume EMX program runs on OS/2, even if compiled under DOS.  */
49# define OS2
50#endif
51
52#if !defined WIN32
53# if HAVE_LANGINFO_CODESET
54#  include <langinfo.h>
55# else
56#  if HAVE_SETLOCALE
57#   include <locale.h>
58#  endif
59# endif
60#elif defined WIN32
61# define WIN32_LEAN_AND_MEAN
62# include <windows.h>
63#endif
64#if defined OS2
65# define INCL_DOS
66# include <os2.h>
67#endif
68
69#if defined _WIN32 || defined __WIN32__ || defined __EMX__ || defined __DJGPP__
70  /* Win32, OS/2, DOS */
71# define ISSLASH(C) ((C) == '/' || (C) == '\\')
72#endif
73
74#ifndef DIRECTORY_SEPARATOR
75# define DIRECTORY_SEPARATOR '/'
76#endif
77
78#ifndef ISSLASH
79# define ISSLASH(C) ((C) == DIRECTORY_SEPARATOR)
80#endif
81
82#ifdef HAVE_GETC_UNLOCKED
83# undef getc
84# define getc getc_unlocked
85#endif
86
87/* The following static variable is declared 'volatile' to avoid a
88   possible multithread problem in the function get_charset_aliases. If we
89   are running in a threaded environment, and if two threads initialize
90   'charset_aliases' simultaneously, both will produce the same value,
91   and everything will be ok if the two assignments to 'charset_aliases'
92   are atomic. But I don't know what will happen if the two assignments mix.  */
93#if __STDC__ != 1
94# define volatile /* empty */
95#endif
96/* Pointer to the contents of the charset.alias file, if it has already been
97   read, else NULL.  Its format is:
98   ALIAS_1 '\0' CANONICAL_1 '\0' ... ALIAS_n '\0' CANONICAL_n '\0' '\0'  */
99static const char * volatile charset_aliases;
100
101/* Return a pointer to the contents of the charset.alias file.  */
102static const char *
103get_charset_aliases ()
104{
105  const char *cp;
106
107  cp = charset_aliases;
108  if (cp == NULL)
109    {
110#if !defined WIN32
111      FILE *fp;
112      const char *dir = LIBDIR;
113      const char *base = "charset.alias";
114      char *file_name;
115
116      /* Concatenate dir and base into freshly allocated file_name.  */
117      {
118	size_t dir_len = strlen (dir);
119	size_t base_len = strlen (base);
120	int add_slash = (dir_len > 0 && !ISSLASH (dir[dir_len - 1]));
121	file_name = (char *) malloc (dir_len + add_slash + base_len + 1);
122	if (file_name != NULL)
123	  {
124	    memcpy (file_name, dir, dir_len);
125	    if (add_slash)
126	      file_name[dir_len] = DIRECTORY_SEPARATOR;
127	    memcpy (file_name + dir_len + add_slash, base, base_len + 1);
128	  }
129      }
130
131      if (file_name == NULL || (fp = fopen (file_name, "r")) == NULL)
132	/* Out of memory or file not found, treat it as empty.  */
133	cp = "";
134      else
135	{
136	  /* Parse the file's contents.  */
137	  int c;
138	  char buf1[50+1];
139	  char buf2[50+1];
140	  char *res_ptr = NULL;
141	  size_t res_size = 0;
142	  size_t l1, l2;
143
144	  for (;;)
145	    {
146	      c = getc (fp);
147	      if (c == EOF)
148		break;
149	      if (c == '\n' || c == ' ' || c == '\t')
150		continue;
151	      if (c == '#')
152		{
153		  /* Skip comment, to end of line.  */
154		  do
155		    c = getc (fp);
156		  while (!(c == EOF || c == '\n'));
157		  if (c == EOF)
158		    break;
159		  continue;
160		}
161	      ungetc (c, fp);
162	      if (fscanf (fp, "%50s %50s", buf1, buf2) < 2)
163		break;
164	      l1 = strlen (buf1);
165	      l2 = strlen (buf2);
166	      if (res_size == 0)
167		{
168		  res_size = l1 + 1 + l2 + 1;
169		  res_ptr = (char *) malloc (res_size + 1);
170		}
171	      else
172		{
173		  res_size += l1 + 1 + l2 + 1;
174		  res_ptr = (char *) realloc (res_ptr, res_size + 1);
175		}
176	      if (res_ptr == NULL)
177		{
178		  /* Out of memory. */
179		  res_size = 0;
180		  break;
181		}
182	      strcpy (res_ptr + res_size - (l2 + 1) - (l1 + 1), buf1);
183	      strcpy (res_ptr + res_size - (l2 + 1), buf2);
184	    }
185	  fclose (fp);
186	  if (res_size == 0)
187	    cp = "";
188	  else
189	    {
190	      *(res_ptr + res_size) = '\0';
191	      cp = res_ptr;
192	    }
193	}
194
195      if (file_name != NULL)
196	free (file_name);
197
198#else
199
200      /* To avoid the troubles of installing a separate file in the same
201	 directory as the DLL and of retrieving the DLL's directory at
202	 runtime, simply inline the aliases here.  */
203
204# if defined WIN32
205      cp = "CP936" "\0" "GBK" "\0"
206	   "CP1361" "\0" "JOHAB" "\0";
207# endif
208#endif
209
210      charset_aliases = cp;
211    }
212
213  return cp;
214}
215
216/* Determine the current locale's character encoding, and canonicalize it
217   into one of the canonical names listed in config.charset.
218   The result must not be freed; it is statically allocated.
219   If the canonical name cannot be determined, the result is a non-canonical
220   name.  */
221
222#ifdef STATIC
223STATIC
224#endif
225const char *
226locale_charset ()
227{
228  const char *codeset;
229  const char *aliases;
230
231#if !(defined WIN32 || defined OS2)
232
233# if HAVE_LANGINFO_CODESET
234
235  /* Most systems support nl_langinfo (CODESET) nowadays.  */
236  codeset = nl_langinfo (CODESET);
237
238# else
239
240  /* On old systems which lack it, use setlocale or getenv.  */
241  const char *locale = NULL;
242
243  /* But most old systems don't have a complete set of locales.  Some
244     (like SunOS 4 or DJGPP) have only the C locale.  Therefore we don't
245     use setlocale here; it would return "C" when it doesn't support the
246     locale name the user has set.  */
247#  if HAVE_SETLOCALE && 0
248  locale = setlocale (LC_CTYPE, NULL);
249#  endif
250  if (locale == NULL || locale[0] == '\0')
251    {
252      locale = getenv ("LC_ALL");
253      if (locale == NULL || locale[0] == '\0')
254	{
255	  locale = getenv ("LC_CTYPE");
256	  if (locale == NULL || locale[0] == '\0')
257	    locale = getenv ("LANG");
258	}
259    }
260
261  /* On some old systems, one used to set locale = "iso8859_1". On others,
262     you set it to "language_COUNTRY.charset". In any case, we resolve it
263     through the charset.alias file.  */
264  codeset = locale;
265
266# endif
267
268#elif defined WIN32
269
270  static char buf[2 + 10 + 1];
271
272  /* Win32 has a function returning the locale's codepage as a number.  */
273  sprintf (buf, "CP%u", GetACP ());
274  codeset = buf;
275
276#elif defined OS2
277
278  const char *locale;
279  static char buf[2 + 10 + 1];
280  ULONG cp[3];
281  ULONG cplen;
282
283  /* Allow user to override the codeset, as set in the operating system,
284     with standard language environment variables.  */
285  locale = getenv ("LC_ALL");
286  if (locale == NULL || locale[0] == '\0')
287    {
288      locale = getenv ("LC_CTYPE");
289      if (locale == NULL || locale[0] == '\0')
290	locale = getenv ("LANG");
291    }
292  if (locale != NULL && locale[0] != '\0')
293    {
294      /* If the locale name contains an encoding after the dot, return it.  */
295      const char *dot = strchr (locale, '.');
296
297      if (dot != NULL)
298	{
299	  const char *modifier;
300
301	  dot++;
302	  /* Look for the possible @... trailer and remove it, if any.  */
303	  modifier = strchr (dot, '@');
304	  if (modifier == NULL)
305	    return dot;
306	  if (modifier - dot < sizeof (buf))
307	    {
308	      memcpy (buf, dot, modifier - dot);
309	      buf [modifier - dot] = '\0';
310	      return buf;
311	    }
312	}
313
314      /* Resolve through the charset.alias file.  */
315      codeset = locale;
316    }
317  else
318    {
319      /* OS/2 has a function returning the locale's codepage as a number.  */
320      if (DosQueryCp (sizeof (cp), cp, &cplen))
321	codeset = "";
322      else
323	{
324	  sprintf (buf, "CP%u", cp[0]);
325	  codeset = buf;
326	}
327    }
328
329#endif
330
331  if (codeset == NULL)
332    /* The canonical name cannot be determined.  */
333    codeset = "";
334
335  /* Resolve alias. */
336  for (aliases = get_charset_aliases ();
337       *aliases != '\0';
338       aliases += strlen (aliases) + 1, aliases += strlen (aliases) + 1)
339    if (strcmp (codeset, aliases) == 0
340	|| (aliases[0] == '*' && aliases[1] == '\0'))
341      {
342	codeset = aliases + strlen (aliases) + 1;
343	break;
344      }
345
346  return codeset;
347}
348