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
  12 #include <langinfo.h>
  13
  14 /* Only get_charset() should use norm_charmap(), so hide its
  15    declaration here. */
  16 char *norm_charmap(char *);
  17
  18 /*
  19  * Get the current character set
  20  */
  21 char *
  22 get_charset ()
  23 {
  24     return norm_charmap(nl_langinfo (CODESET));
  25 }
  26
  27
  28 /*
  29  * Check if we can display a given character set natively.
  30  * We are passed the length of the initial part of the
  31  * string to check, since we want to allow the name of the
  32  * character set to be a substring of a larger string.
  33  */
  34
  35 int
  36 check_charset (char *str, int len)
  37 {
  38     static char *mm_charset = NULL;
  39     static char *alt_charset = NULL;
  40     static int mm_len;
  41     static int alt_len;
  42
  43     /* Cache the name of our default character set */
  44     if (!mm_charset) {
  45         if (!(mm_charset = get_charset ()))
  46             mm_charset = "US-ASCII";
  47         mm_len = strlen (mm_charset);
  48
  49         /* US-ASCII is a subset of the ISO-8859-X and UTF-8 character sets */
  50         if (!strncasecmp("ISO-8859-", mm_charset, 9) ||
  51                 !strcasecmp("UTF-8", mm_charset)) {
  52             alt_charset = "US-ASCII";
  53             alt_len = strlen (alt_charset);
  54         }
  55     }
  56
  57     /* Check if character set is OK */
  58     if ((len == mm_len) && !strncasecmp(str, mm_charset, mm_len))
  59         return 1;
  60     if (alt_charset && (len == alt_len) && !strncasecmp(str, alt_charset, alt_len))
  61         return 1;
  62
  63     return 0;
  64 }
  65
  66
  67 /*
  68  * Return the name of the character set we are
  69  * using for 8bit text.
  70  */
  71 char *
  72 write_charset_8bit (void)
  73 {
  74     static char *mm_charset = NULL;
  75
  76     /*
  77      * Cache the name of the character set to
  78      * use for 8bit text.
  79      */
  80     if (!mm_charset && !(mm_charset = get_charset ()))
  81             mm_charset = "x-unknown";
  82
  83     return mm_charset;
  84 }