X-Git-Url: https://diplodocus.org/git/nmh/blobdiff_plain/6c42153ad9362cc676ea66563bf400d7511b3b68..c576ad2674c37a1c63f004c71049998f38854c64:/sbr/check_charset.c

diff --git a/sbr/check_charset.c b/sbr/check_charset.c
index 5d98774c..71129fef 100644
--- a/sbr/check_charset.c
+++ b/sbr/check_charset.c
@@ -1,8 +1,4 @@
-
-/*
- * 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
@@ -11,6 +7,21 @@
 
 #include <h/mh.h>
 
+#include <string.h>
+#include <langinfo.h>
+
+static const char *norm_charmap(char *name);
+
+/*
+ * Get the current character set
+ */
+char *
+get_charset(void)
+{
+    return (char *)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
@@ -28,12 +39,13 @@ check_charset (char *str, int len)
 
     /* Cache the name of our default character set */
     if (!mm_charset) {
-	if (!(mm_charset = getenv ("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 character sets */
-	if (!strncasecmp("ISO-8859-", mm_charset, 9)) {
+	/* 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);
 	}
@@ -62,8 +74,111 @@ write_charset_8bit (void)
      * Cache the name of the character set to
      * use for 8bit text.
      */
-    if (!mm_charset && !(mm_charset = getenv ("MM_CHARSET")))
+    if (!mm_charset && !(mm_charset = get_charset ()))
 	    mm_charset = "x-unknown";
 
     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;
+}