diplodocus.org Git - nmh/blob - sbr/check_charset.c

   1
   2 /*
   3  * check_charset.c -- routines for character sets
   4  *
   5  * This code is Copyright (c) 2002, by the authors of nmh.  See the
   6  * COPYRIGHT file in the root directory of the nmh distribution for
   7  * complete copyright information.
   8  */
   9
  10 #include <h/mh.h>
  11 #ifdef HAVE_LANGINFO_H
  12 # include <langinfo.h>
  13 #endif
  14
  15
  16 /*
  17  * Get the current character set
  18  */
  19 char *
  20 get_charset ()
  21 {
  22     char *charset = getenv ("MM_CHARSET");
  23 #if defined(HAVE_NL_LANGINFO) && defined(CODESET)
  24     if (!charset)
  25         charset = norm_charmap(nl_langinfo (CODESET));
  26 #endif
  27     return charset;
  28 }
  29
  30
  31 /*
  32  * Check if we can display a given character set natively.
  33  * We are passed the length of the initial part of the
  34  * string to check, since we want to allow the name of the
  35  * character set to be a substring of a larger string.
  36  */
  37
  38 int
  39 check_charset (char *str, int len)
  40 {
  41     static char *mm_charset = NULL;
  42     static char *alt_charset = NULL;
  43     static int mm_len;
  44     static int alt_len;
  45
  46     /* Cache the name of our default character set */
  47     if (!mm_charset) {
  48         if (!(mm_charset = get_charset ()))
  49             mm_charset = "US-ASCII";
  50         mm_len = strlen (mm_charset);
  51
  52         /* US-ASCII is a subset of the ISO-8859-X and UTF-8 character sets */
  53         if (!strncasecmp("ISO-8859-", mm_charset, 9) ||
  54                 !mh_strcasecmp("UTF-8", mm_charset)) {
  55             alt_charset = "US-ASCII";
  56             alt_len = strlen (alt_charset);
  57         }
  58     }
  59
  60     /* Check if character set is OK */
  61     if ((len == mm_len) && !strncasecmp(str, mm_charset, mm_len))
  62         return 1;
  63     if (alt_charset && (len == alt_len) && !strncasecmp(str, alt_charset, alt_len))
  64         return 1;
  65
  66     return 0;
  67 }
  68
  69
  70 /*
  71  * Return the name of the character set we are
  72  * using for 8bit text.
  73  */
  74 char *
  75 write_charset_8bit (void)
  76 {
  77     static char *mm_charset = NULL;
  78
  79     /*
  80      * Cache the name of the character set to
  81      * use for 8bit text.
  82      */
  83     if (!mm_charset && !(mm_charset = get_charset ()))
  84             mm_charset = "x-unknown";
  85
  86     return mm_charset;
  87 }