4 files changed, 38 insertions, 2 deletions
diff --git a/gtk/src/main.c b/gtk/src/main.c
index efc2fbc99..2c732079e 100644
--- a/gtk/src/main.c
+++ b/gtk/src/main.c
@@ -697,6 +697,21 @@ main (int argc, char *argv[])
 	ghb_hal_init();
 #endif
 
+	if (!ghb_lock_file("queue_lock"))
+	{
+    	const gchar *markup =
+        	N_("<b><big>Another instance of HandBrake is already running.</big></b>\n"
+        	"\n"
+        	"Only one instance of HandBrake may run.\n");
+        GtkWidget *dialog = gtk_message_dialog_new_with_markup(NULL,
+            GTK_DIALOG_MODAL,
+            GTK_MESSAGE_ERROR,
+            GTK_BUTTONS_CLOSE,
+            _(markup));
+        gtk_dialog_run(GTK_DIALOG(dialog));
+        gtk_widget_destroy(dialog);
+        exit(EXIT_FAILURE);
+	}
 	ud = g_malloc0(sizeof(signal_user_data_t));
 	ud->debug = ghb_debug;
 	g_log_set_handler (NULL, G_LOG_LEVEL_DEBUG, debug_log_handler, ud);
diff --git a/gtk/src/presets.c b/gtk/src/presets.c
index 7d3151906..75354b165 100644
--- a/gtk/src/presets.c
+++ b/gtk/src/presets.c
@@ -11,6 +11,10 @@
  * any later version.
  * 
  */
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
 #include <glib.h>
 #include <glib-object.h>
 #include <glib/gstdio.h>
@@ -1112,6 +1116,24 @@ load_plist(const gchar *name)
 	return plist;
 }
 
+gboolean
+ghb_lock_file(const gchar *name)
+{
+	gchar *config, *path;
+	int fd, lock = 0;
+
+	config = ghb_get_user_config_dir(NULL);
+	path = g_strdup_printf ("%s/%s", config, name);
+	fd = open(path, O_RDWR|O_CREAT, S_IRUSR|S_IWUSR);
+	if (fd >= 0)
+		lock = lockf(fd, F_TLOCK, 0);
+	if (lock)
+		close(fd);
+	g_free(config);
+	g_free(path);
+	return !lock;
+}
+
 static void
 remove_plist(const gchar *name)
 {
diff --git a/gtk/src/presets.h b/gtk/src/presets.h
index 8c05f1978..65b4e8cd0 100644
--- a/gtk/src/presets.h
+++ b/gtk/src/presets.h
@@ -40,5 +40,6 @@ gchar* ghb_preset_path_string(const GValue *path);
 gboolean ghb_preset_is_custom(void);
 void ghb_prefs_store(void);
 void ghb_pref_set(GValue *settings, const gchar *key);
+gboolean ghb_lock_file(const gchar *name);
 
 #endif // _GHB_PRESETS_H_
diff --git a/gtk/src/preview.c b/gtk/src/preview.c
index 577cbd557..9fd92bf53 100644
--- a/gtk/src/preview.c
+++ b/gtk/src/preview.c
@@ -946,8 +946,6 @@ picture_settings_alt2_clicked_cb(GtkWidget *xwidget, signal_user_data_t *ud)
 {
 	GtkWidget *toggle;
 	gboolean active;
-	gint signal_id;
-	gint handler_id = 0;
 	GtkWidget *window;
 
 	g_debug("picture_settings_alt2_clicked_cb()");