-
-/*
- * check_charset.c -- routines for character sets
- *
- * $Id$
+/* check_charset.c -- routines for character sets
*
* This code is Copyright (c) 2002, by the authors of nmh. See the
* COPYRIGHT file in the root directory of the nmh distribution for
*/
#include <h/mh.h>
-#ifdef HAVE_LANGINFO_H
-# include <langinfo.h>
-#endif
+#include <string.h>
+#include <langinfo.h>
+
+static const char *norm_charmap(char *name);
/*
* Get the current character set
*/
char *
-get_charset ()
+get_charset(void)
{
- char *charset = getenv ("MM_CHARSET");
-#if defined(HAVE_NL_LANGINFO) && defined(CODESET)
- if (!charset)
- charset = norm_charmap(nl_langinfo (CODESET));
-#endif
- return charset;
+ return (char *)norm_charmap(nl_langinfo(CODESET));
}
return mm_charset;
}
+
+/* The Single Unix Specification function nl_langinfo(CODESET)
+ * returns the name of the encoding used by the currently selected
+ * locale:
+ *
+ * http://www.opengroup.org/onlinepubs/7908799/xsh/langinfo.h.html
+ *
+ * Unfortunately the encoding names are not yet standardized.
+ * This function knows about the encoding names used on many
+ * different systems and converts them where possible into
+ * the corresponding MIME charset name registered in
+ *
+ * http://www.iana.org/assignments/character-sets
+ *
+ * Please extend it as needed and suggest improvements to the author.
+ *
+ * Markus.Kuhn@cl.cam.ac.uk -- 2002-03-11
+ * Permission to use, copy, modify, and distribute this software
+ * for any purpose and without fee is hereby granted. The author
+ * disclaims all warranties with regard to this software.
+ *
+ * Latest version:
+ *
+ * http://www.cl.cam.ac.uk/~mgk25/ucs/norm_charmap.c
+ */
+
+static const char *norm_charmap(char *name)
+{
+ static const char *correct[] = {
+ "UTF-8",
+ "US-ASCII",
+ NULL
+ }, **cor;
+ static struct {
+ const char *alias;
+ const char *name;
+ } *ali, aliases[] = {
+ /* Names for US-ASCII. */
+ { "ANSI_X3.4-1968", "US-ASCII" }, /* LC_ALL=C. */
+ { "ASCII", "US-ASCII" },
+ { "646", "US-ASCII" },
+ { "ISO646", "US-ASCII" },
+ { "ISO_646.IRV", "US-ASCII" },
+ /* Case differs. */
+ { "BIG5", "Big5" },
+ { "BIG5HKSCS", "Big5HKSCS" },
+ /* Names for ISO-8859-11. */
+ { "TIS-620", "ISO-8859-11" },
+ { "TIS620.2533", "ISO-8859-11" },
+ { NULL, NULL }
+ };
+ static struct {
+ const char *substr;
+ const char *name;
+ } *sub, substrs[] = {
+ { "8859-1", "ISO-8859-1" },
+ { "8859-2", "ISO-8859-2" },
+ { "8859-3", "ISO-8859-3" },
+ { "8859-4", "ISO-8859-4" },
+ { "8859-5", "ISO-8859-5" },
+ { "8859-6", "ISO-8859-6" },
+ { "8859-7", "ISO-8859-7" },
+ { "8859-8", "ISO-8859-8" },
+ { "8859-9", "ISO-8859-9" },
+ { "8859-10", "ISO-8859-10" },
+ { "8859-11", "ISO-8859-11" },
+ /* 12, Latin/Devanagari, not completed. */
+ { "8859-13", "ISO-8859-13" },
+ { "8859-14", "ISO-8859-14" },
+ { "8859-15", "ISO-8859-15" },
+ { "8859-16", "ISO-8859-16" },
+ { "CP1200", "WINDOWS-1200" },
+ { "CP1201", "WINDOWS-1201" },
+ { "CP1250", "WINDOWS-1250" },
+ { "CP1251", "WINDOWS-1251" },
+ { "CP1252", "WINDOWS-1252" },
+ { "CP1253", "WINDOWS-1253" },
+ { "CP1254", "WINDOWS-1254" },
+ { "CP1255", "WINDOWS-1255" },
+ { "CP1256", "WINDOWS-1256" },
+ { "CP1257", "WINDOWS-1257" },
+ { "CP1258", "WINDOWS-1258" },
+ { NULL, NULL }
+ };
+
+ if (!name)
+ return name;
+
+ /* Avoid lots of tests for common correct names. */
+ for (cor = correct; *cor; cor++)
+ if (!strcmp(name, *cor))
+ return name;
+
+ for (ali = aliases; ali->alias; ali++)
+ if (!strcmp(name, ali->alias))
+ return ali->name;
+
+ for (sub = substrs; sub->substr; sub++)
+ if (strstr(name, sub->substr))
+ return sub->name;
+
+ return name;
+}