Add workaroud to prevents Glade from crashing when loading GJS plugin on X11 backend

2 files changed, 96 insertions, 0 deletions

diff --git a/src/main.c b/src/main.c
index 1107d8a3..40517648 100644
--- a/src/main.c
+++ b/src/main.c
@@ -147,6 +147,8 @@ open (GApplication  *application,
   if (verbose) g_timer_destroy (timer);
 }
 
+#include "workaround.h"
+
 int
 main (int argc, char *argv[])
 {
@@ -163,6 +165,14 @@ main (int argc, char *argv[])
 
   gtk_init (&argc, &argv);
 
+  /* FIXME:
+   *
+   * This prevents glade from crashing when loading GJS plugin on X11 backend
+   */
+#ifdef GDK_WINDOWING_X11
+  _init_cairo_xlib_workaround ();
+#endif
+
   app = gtk_application_new ("org.gnome.Glade", G_APPLICATION_HANDLES_OPEN);
 
   g_application_set_option_context_summary (G_APPLICATION (app),
diff --git a/src/workaround.h b/src/workaround.h
new file mode 100644
index 00000000..922cba2d
--- /dev/null
+++ b/src/workaround.h
@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2020 Juan Pablo Ugarte.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Authors:
+ *   Juan Pablo Ugarte <juanpablougarte@gmail.com>
+ */
+
+#ifdef GDK_WINDOWING_X11
+
+#include <gdk/gdkx.h>
+
+/*
+ * Loading gladegjs plugin makes cairo_xlib crash while trying to render a label
+ * in a mutext lock deep in the stack, to avoid this we create an offscreen
+ * label and wait for it to be drawn on the screen so that the mutex get
+ * properly initialized and the crash is avoided.
+ *
+ * #0  __GI___pthread_mutex_lock (mutex=0x0) at ../nptl/pthread_mutex_lock.c:67
+ * #1  0x00007ffff6ae430b in XrmQGetResource
+ * (db=0x555555778b70, names=names@entry=0x7fffffffa6f0, classes=classes@entry=0x7fffffffa6fc, pType=pType@entry=0x7fffffffa6dc, pValue=pValue@entry=0x7fffffffa6e0) at ../../src/Xrm.c:2549
+ * #2  0x00007ffff6ac02c6 in XGetDefault
+ * (dpy=dpy@entry=0x5555555a39a0, prog=prog@entry=0x7ffff748fe01 "Xft", name=name@entry=0x7ffff7491594 "antialias")
+ * at ../../src/GetDflt.c:231
+ * #3  0x00007ffff744323e in get_boolean_default (value=<synthetic pointer>, option=0x7ffff7491594 "antialias", dpy=0x5555555a39a0)
+ * at ../../../../src/cairo-xlib-screen.c:146
+ * #4  _cairo_xlib_init_screen_font_options (info=0x555555d7b930, dpy=0x5555555a39a0) at ../../../../src/cairo-xlib-screen.c:146
+ */
+
+static void
+check_for_draw (GdkEvent *event, gpointer loop)
+{
+  if (event->type == GDK_EXPOSE)
+    {
+      g_main_loop_quit (loop);
+      gdk_event_handler_set ((GdkEventFunc) gtk_main_do_event, NULL, NULL);
+    }
+
+  gtk_main_do_event (event);
+}
+
+/* Taken from Gtk sources gtk-reftest.c  */
+static void
+wait_for_drawing (GdkWindow *window)
+{
+  GMainLoop *loop;
+
+  loop = g_main_loop_new (NULL, FALSE);
+  gdk_event_handler_set (check_for_draw, loop, NULL);
+  g_main_loop_run (loop);
+}
+
+static void
+_init_cairo_xlib_workaround ()
+{
+  GdkDisplay *display = gdk_display_get_default ();
+  GtkWidget *win;
+
+  /* This is only needed on X11 */
+  if (!GDK_IS_X11_DISPLAY (display))
+    return;
+
+  win = gtk_offscreen_window_new ();
+  gtk_container_add (GTK_CONTAINER (win),
+                     gtk_label_new ("Foo"));
+  gtk_widget_show_all (win);
+
+  wait_for_drawing (gtk_widget_get_window (win));
+
+  gtk_widget_destroy (win);
+}
+
+#endif