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

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