Index: update-mime-database.c
===================================================================
RCS file: /cvs/mime/shared-mime-info/update-mime-database.c,v
retrieving revision 1.30
diff -u -p -r1.30 update-mime-database.c
--- update-mime-database.c	13 Oct 2003 09:43:38 -0000	1.30
+++ update-mime-database.c	11 Sep 2004 06:27:48 -0000
@@ -94,6 +94,9 @@ static GHashTable *globs_hash = NULL;
 /* 'magic' nodes */
 static GPtrArray *magic_array = NULL;
 
+/* Maps MIME type names to superclass names */
+static GHashTable *subclass_hash = NULL;
+
 /* Static prototypes */
 static Magic *magic_new(xmlNode *node, Type *type, GError **error);
 
@@ -245,6 +248,17 @@ static void add_namespace(Type *type, co
 			type);
 }
 
+static void
+insert_subclass (gchar *type, gchar *parent)
+{
+	GSList *list, *nlist;
+
+	list = g_hash_table_lookup (subclass_hash, type);
+	nlist = g_slist_append (list, g_strdup (parent));
+	if (list == NULL)
+		g_hash_table_insert(subclass_hash, g_strdup (type), nlist);    
+}
+
 /* 'field' was found in the definition of 'type' and has the freedesktop.org
  * namespace. If it's a known field, process it and return TRUE, else
  * return FALSE to add it to the output XML document.
@@ -297,10 +311,23 @@ static gboolean process_freedesktop_node
 		gboolean valid;
 		other_type = xmlGetNsProp(field, "type", NULL);
 		valid = other_type && strchr(other_type, '/');
-		xmlFree(other_type);
 		if (valid)
-			return FALSE;	/* Copy through */
+		{
+			char *typename;
 
+			typename = g_strdup_printf("%s/%s", 
+						   type->media,
+						   type->subtype);
+			insert_subclass(typename, other_type);
+			if (strcmp(field->name, "alias") == 0)
+				insert_subclass(other_type, typename);
+			g_free(typename);
+			xmlFree(other_type);
+			
+			return FALSE;	/* Copy through */
+		}
+		
+		xmlFree(other_type);
 		g_set_error(error, MIME_ERROR, 0,
 			_("Incorrect or missing 'type' attribute "
 			  "in <%s>"), field->name);
@@ -1310,6 +1337,27 @@ static void write_namespaces(FILE *strea
 	g_ptr_array_free(lines, TRUE);
 }
 
+static void write_subclass(gpointer key, gpointer value, gpointer data)
+{
+	GSList *list = value;
+	FILE *stream = data;
+	GSList *l;
+	char *line;
+
+	for (l = list; l; l = l->next)
+	{
+		line = g_strconcat (key, ":", l->data, "\n", NULL);
+		fwrite(line, 1, strlen(line), stream);
+		g_free (line);
+	}
+}
+
+/* Write all the collected subclass information to 'subclasses' */
+static void write_subclasses(FILE *stream)
+{
+	g_hash_table_foreach(subclass_hash, write_subclass, stream);
+}
+
 /* Issue a warning if 'path' won't be found by applications */
 static void check_in_path_xdg_data(const char *mime_path)
 {
@@ -1371,6 +1419,15 @@ out:
 	g_free(path);
 }
 
+static void 
+free_string_list (gpointer data)
+{
+  GSList *list = data;
+
+  g_slist_foreach (list, g_free, NULL);
+  g_slist_free (list);
+}
+
 int main(int argc, char **argv)
 {
 	char *mime_dir = NULL;
@@ -1442,7 +1499,9 @@ int main(int argc, char **argv)
 	namespace_hash = g_hash_table_new_full(g_str_hash, g_str_equal,
 					g_free, NULL);
 	magic_array = g_ptr_array_new();
-
+	subclass_hash = g_hash_table_new_full(g_str_hash, g_str_equal,
+					      g_free, free_string_list);
+	
 	scan_source_dir(package_dir);
 	g_free(package_dir);
 
@@ -1494,7 +1553,7 @@ int main(int argc, char **argv)
 		atomic_update(magic_path);
 		g_free(magic_path);
 	}
-	
+
 	{
 		FILE *stream;
 		char *ns_path;
@@ -1510,12 +1569,30 @@ int main(int argc, char **argv)
 		atomic_update(ns_path);
 		g_free(ns_path);
 	}
+	
+	{
+		FILE *stream;
+		char *path;
+		
+		path = g_strconcat(mime_dir, "/subclasses.new", NULL);
+		stream = fopen(path, "wb");
+		if (!stream)
+			g_error("Failed to open '%s' for writing\n",
+				path);
+		
+		write_subclasses(stream);
+
+		atomic_update(path);
+		g_free(path);
+	}
+
 
 	g_ptr_array_free(magic_array, TRUE);
 
 	g_hash_table_destroy(types);
 	g_hash_table_destroy(globs_hash);
 	g_hash_table_destroy(namespace_hash);
+	g_hash_table_destroy(subclass_hash);
 
 	g_print("***\n");
 
Index: shared-mime-info-spec.xml
===================================================================
RCS file: /cvs/mime/shared-mime-info/shared-mime-info-spec.xml,v
retrieving revision 1.53
diff -u -p -r1.53 shared-mime-info-spec.xml
--- shared-mime-info-spec.xml	11 May 2004 10:33:33 -0000	1.53
+++ shared-mime-info-spec.xml	11 Sep 2004 06:27:48 -0000
@@ -165,6 +165,9 @@ The files created by <command>update-mim
 <filename>&lt;MIME&gt;/magic</filename> (contains a mapping from file contents to MIME types)
 				</para></listitem>
 				<listitem><para>
+<filename>&lt;MIME&gt;/subclasses</filename> (contains a mapping from MIME types to types they inherit from or alias with)
+				</para></listitem>
+				<listitem><para>
 <filename>&lt;MIME&gt;/XMLnamespaces</filename> (contains a mapping from XML
 (namespaceURI, localName) pairs to MIME types)
 				</para></listitem>