[libcaja-private] Re-check file MIME type before picking an application.

An example of when the MIME type might change: a file is initially created
with 0 bytes of content, but more data is added later. Empty files are always
detected as plain text, but the file might not be empty anymore when the user
opens it.

This commit affects the behavior when double-clicking a file and when right-
clicking on it too.

libcaja-private/caja-file.c

@@ -2555,6 +2555,24 @@ caja_file_update_info (CajaFile *file,
 	return update_info_internal (file, info, FALSE);
 }
 
+void
+caja_file_refresh_info (CajaFile *file)
+{
+	GFile *gfile;
+	GFileInfo *new_info;
+
+	gfile = caja_file_get_location (file);
+	new_info = g_file_query_info (gfile, CAJA_FILE_DEFAULT_ATTRIBUTES,
+	                              G_FILE_QUERY_INFO_NONE, NULL, NULL);
+	if (new_info != NULL) {
+		if (caja_file_update_info (file, new_info)) {
+			caja_file_changed (file);
+		}
+		g_object_unref (new_info);
+	}
+	g_object_unref (gfile);
+}
+
 static gboolean
 update_name_internal (CajaFile *file,
 		      const char *name,

libcaja-private/caja-file.h

@@ -144,6 +144,12 @@ void                    caja_file_monitor_add                       (CajaFile
 void                    caja_file_monitor_remove                    (CajaFile                   *file,
         gconstpointer                   client);
 
+/* Synchronously refreshes file info from disk.
+ * This can call caja_file_changed, so don't call this function from any
+ * of the callbacks for that event.
+ */
+void                     caja_file_refresh_info                     (CajaFile                   *file);
+
 /* Waiting for data that's read asynchronously.
  * This interface currently works only for metadata, but could be expanded
  * to other attributes as well.

libcaja-private/caja-mime-actions.c

@@ -997,6 +997,12 @@ make_activation_parameters (GList *uris,
         uri = l->data;
         file = caja_file_get_by_uri (uri);
 
+        /* Double-check if a file's MIME type has changed before we commit to a
+           choice of application for it. This can happen if, for instance, file
+           was originally created with 0 bytes and then content was added to it
+           later-- it will change from plaintext to something else. */
+        caja_file_refresh_info (file);
+
         app = caja_mime_get_default_application_for_file (file);
         if (app != NULL)
         {

src/file-manager/fm-directory-view.c

@@ -8813,6 +8813,13 @@ real_update_menus (FMDirectoryView *view)
 
 		file = CAJA_FILE (l->data);
 
+		/* Double-check if the files' MIME types have changed before we
+		   commit to a choice of applications for them. This can happen
+		   if, for instance, a file was originally created with 0 bytes
+		   and then content was added to it later-- it will change from
+		   plaintext to something else. */
+		caja_file_refresh_info (file);
+
 		if (!caja_mime_file_opens_in_external_app (file)) {
 			show_app = FALSE;
 		}