-/* check_charset.c -- routines for character sets
+/* norm_charmap.c -- map locale's encoding to MIME charset.
*
- * This code is Copyright (c) 2002, by the authors of nmh. See the
- * COPYRIGHT file in the root directory of the nmh distribution for
- * complete copyright information.
+ * 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
*/
-#include <h/mh.h>
+#include <string.h>
-#include <langinfo.h>
+#define digit(x) ((x) >= '0' && (x) <= '9')
-/* Only get_charset() should use norm_charmap(), so hide its
- declaration here. */
-char *norm_charmap(char *);
+static char buf[16];
-/*
- * Get the current character set
- */
char *
-get_charset(void)
-{
- return norm_charmap(nl_langinfo (CODESET));
-}
-
-
-/*
- * Check if we can display a given character set natively.
- * We are passed the length of the initial part of the
- * string to check, since we want to allow the name of the
- * character set to be a substring of a larger string.
- */
-
-int
-check_charset (char *str, int len)
+norm_charmap(char *name)
{
- static char *mm_charset = NULL;
- static char *alt_charset = NULL;
- static int mm_len;
- static int alt_len;
+ char *p;
+
+ if (!name)
+ return name;
+
+ /* Many need no remapping, but they are listed here so you
+ * can see what output to expect, and modify for your needs
+ * as necessary. */
+ if (!strcmp(name, "UTF-8"))
+ return "UTF-8";
+ if (!strcmp(name, "EUC-JP"))
+ return "EUC-JP";
+ if (!strcmp(name, "EUC-KR"))
+ return "EUC-KR";
+ if (!strcmp(name, "EUC-TW"))
+ return "EUC-TW";
+ if (!strcmp(name, "KOI8-R"))
+ return "KOI8-R";
+ if (!strcmp(name, "KOI8-U"))
+ return "KOI8-U";
+ if (!strcmp(name, "GBK"))
+ return "GBK";
+ if (!strcmp(name, "GB2312"))
+ return "GB2312";
+ if (!strcmp(name, "GB18030"))
+ return "GB18030";
+ if (!strcmp(name, "VSCII"))
+ return "VSCII";
+
+ /* ASCII comes in many names */
+ if (!strcmp(name, "ASCII") ||
+ !strcmp(name, "US-ASCII") ||
+ !strcmp(name, "ANSI_X3.4-1968") ||
+ !strcmp(name, "646") ||
+ !strcmp(name, "ISO646") ||
+ !strcmp(name, "ISO_646.IRV"))
+ return "US-ASCII";
- /* Cache the name of our default character set */
- if (!mm_charset) {
- if (!(mm_charset = get_charset ()))
- mm_charset = "US-ASCII";
- mm_len = strlen (mm_charset);
-
- /* US-ASCII is a subset of the ISO-8859-X and UTF-8 character sets */
- if (!strncasecmp("ISO-8859-", mm_charset, 9) ||
- !strcasecmp("UTF-8", mm_charset)) {
- alt_charset = "US-ASCII";
- alt_len = strlen (alt_charset);
- }
+ /* ISO 8859 will be converted to "ISO-8859-x" */
+ if ((p = strstr(name, "8859-"))) {
+ memcpy(buf, "ISO-8859-\0\0", 12);
+ p += 5;
+ if (digit(*p)) {
+ buf[9] = *p++;
+ if (digit(*p)) buf[10] = *p++;
+ return buf;
}
+ }
- /* Check if character set is OK */
- if ((len == mm_len) && !strncasecmp(str, mm_charset, mm_len))
- return 1;
- if (alt_charset && (len == alt_len) && !strncasecmp(str, alt_charset, alt_len))
- return 1;
-
- return 0;
-}
-
+ /* Windows code pages will be converted to "WINDOWS-12xx" */
+ if ((p = strstr(name, "CP12"))) {
+ memcpy(buf, "WINDOWS-12\0\0", 13);
+ p += 4;
+ if (digit(*p)) {
+ buf[10] = *p++;
+ if (digit(*p)) buf[11] = *p++;
+ return buf;
+ }
+ }
-/*
- * Return the name of the character set we are
- * using for 8bit text.
- */
-char *
-write_charset_8bit (void)
-{
- static char *mm_charset = NULL;
+ /* TIS-620 comes in at least the following two forms */
+ if (!strcmp(name, "TIS-620") ||
+ !strcmp(name, "TIS620.2533"))
+ return "ISO-8859-11";
- /*
- * Cache the name of the character set to
- * use for 8bit text.
- */
- if (!mm_charset && !(mm_charset = get_charset ()))
- mm_charset = "x-unknown";
+ /* For some, uppercase/lowercase might differ */
+ if (!strcmp(name, "Big5") || !strcmp(name, "BIG5"))
+ return "Big5";
+ if (!strcmp(name, "Big5HKSCS") || !strcmp(name, "BIG5HKSCS"))
+ return "Big5HKSCS";
- return mm_charset;
+ /* I don't know of any implementation of nl_langinfo(CODESET) out
+ * there that returns anything else (and I'm not even certain all of
+ * the above occur in the wild), but just in case, as a fallback,
+ * return the unmodified name. */
+ return name;
}
projects / nmh / blobdiff