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/* Determine a canonical name for the current locale's character encoding.
Copyright (C) 2000 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU Library General Public License as published
by the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
USA. */
/* Written by Bruno Haible <haible@clisp.cons.org>. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#if HAVE_STDDEF_H
# include <stddef.h>
#endif
#include <stdio.h>
#if HAVE_STRING_H
# include <string.h>
#else
# include <strings.h>
#endif
#if HAVE_STDLIB_H
# include <stdlib.h>
#endif
#if HAVE_LANGINFO_CODESET
# include <langinfo.h>
#else
# if HAVE_SETLOCALE
# include <locale.h>
# endif
#endif
#ifndef DIRECTORY_SEPARATOR
# define DIRECTORY_SEPARATOR '/'
#endif
#ifndef ISSLASH
# define ISSLASH(C) ((C) == DIRECTORY_SEPARATOR)
#endif
/* The following static variable is declared 'volatile' to avoid a
possible multithread problem in the function get_charset_aliases. If we
are running in a threaded environment, and if two threads initialize
'charset_aliases' simultaneously, both will produce the same value,
and everything will be ok if the two assignments to 'charset_aliases'
are atomic. But I don't know what will happen if the two assignments mix. */
/* Pointer to the contents of the charset.alias file, if it has already been
read, else NULL. Its format is:
ALIAS_1 '\0' CANONICAL_1 '\0' ... ALIAS_n '\0' CANONICAL_n '\0' '\0' */
static char * volatile charset_aliases;
/* Return a pointer to the contents of the charset.alias file. */
static const char *
get_charset_aliases ()
{
char *cp;
cp = charset_aliases;
if (cp == NULL)
{
FILE *fp;
const char *dir = LIBDIR;
const char *base = "charset.alias";
char *file_name;
/* Concatenate dir and base into freshly allocated file_name. */
{
size_t dir_len = strlen (dir);
size_t base_len = strlen (base);
int add_slash = (dir_len > 0 && !ISSLASH (dir[dir_len - 1]));
file_name = (char *) malloc (dir_len + add_slash + base_len + 1);
if (file_name != NULL)
{
memcpy (file_name, dir, dir_len);
if (add_slash)
file_name[dir_len] = DIRECTORY_SEPARATOR;
memcpy (file_name + dir_len + add_slash, base, base_len + 1);
}
}
if (file_name == NULL || (fp = fopen (file_name, "r")) == NULL)
/* Out of memory or file not found, treat it as empty. */
cp = "";
else
{
/* Parse the file's contents. */
int c;
char buf1[50+1];
char buf2[50+1];
char *res_ptr = NULL;
size_t res_size = 0;
size_t l1, l2;
for (;;)
{
c = getc (fp);
if (c == EOF)
break;
if (c == '\n' || c == ' ' || c == '\t')
continue;
if (c == '#')
{
/* Skip comment, to end of line. */
do
c = getc (fp);
while (!(c == EOF || c == '\n'));
if (c == EOF)
break;
continue;
}
ungetc (c, fp);
if (fscanf(fp, "%50s %50s", buf1, buf2) < 2)
break;
l1 = strlen (buf1);
l2 = strlen (buf2);
if (res_size == 0)
{
res_size = l1 + 1 + l2 + 1;
res_ptr = malloc (res_size + 1);
}
else
{
res_size += l1 + 1 + l2 + 1;
res_ptr = realloc (res_ptr, res_size + 1);
}
if (res_ptr == NULL)
{
/* Out of memory. */
res_size = 0;
break;
}
strcpy (res_ptr + res_size - (l2 + 1) - (l1 + 1), buf1);
strcpy (res_ptr + res_size - (l2 + 1), buf2);
}
fclose (fp);
if (res_size == 0)
cp = "";
else
{
*(res_ptr + res_size) = '\0';
cp = res_ptr;
}
}
charset_aliases = cp;
if (file_name != NULL)
free (file_name);
}
return cp;
}
/* Determine the current locale's character encoding, and canonicalize it
into one of the canonical names listed in config.charset.
The result must not be freed; it is statically allocated.
If the canonical name cannot be determined, the result is a non-canonical
name or NULL. */
#ifdef STATIC
STATIC
#endif
const char *
locale_charset ()
{
const char *codeset;
const char *aliases;
#if HAVE_LANGINFO_CODESET
/* Most systems support nl_langinfo (CODESET) nowadays. */
codeset = nl_langinfo (CODESET);
#else
/* On old systems which lack it, use setlocale and getenv. */
const char *locale = NULL;
# if HAVE_SETLOCALE
locale = setlocale (LC_CTYPE, NULL);
# endif
if (locale == NULL || locale[0] == '\0')
{
locale = getenv ("LC_ALL");
if (locale == NULL || locale[0] == '\0')
{
locale = getenv ("LC_CTYPE");
if (locale == NULL || locale[0] == '\0')
locale = getenv ("LANG");
}
}
/* On some old systems, one used to set locale = "iso8859_1". On others,
you set it to "language_COUNTRY.charset". In any case, we resolve it
through the charset.alias file. */
codeset = locale;
#endif
if (codeset != NULL && codeset[0] != '\0')
{
/* Resolve alias. */
for (aliases = get_charset_aliases ();
*aliases != '\0';
aliases += strlen (aliases) + 1, aliases += strlen (aliases) + 1)
if (!strcmp (codeset, aliases))
{
codeset = aliases + strlen (aliases) + 1;
break;
}
}
return codeset;
}
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