[mutter] monitor-manager-xrandr: Ignore outputs without modes

[Rui Matos <rtcm src gnome org>]

commit 86a913d37aae4c96cb2e4d765b58fb4f60ec9d54
Author: Rui Matos <tiagomatos gmail com>
Date:   Tue Oct 20 16:01:30 2015 +0200

    monitor-manager-xrandr: Ignore outputs without modes
    
    In some cases we get outputs without any valid mode. We need to ignore
    them or we'll crash later.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=756796

 src/backends/x11/meta-monitor-manager-xrandr.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)
---
diff --git a/src/backends/x11/meta-monitor-manager-xrandr.c b/src/backends/x11/meta-monitor-manager-xrandr.c
index 0acb217..a555243 100644
--- a/src/backends/x11/meta-monitor-manager-xrandr.c
+++ b/src/backends/x11/meta-monitor-manager-xrandr.c
@@ -808,6 +808,15 @@ meta_monitor_manager_xrandr_read_current (MetaMonitorManager *manager)
        {
           GBytes *edid;
 
+          /* Get this first so that if there are no valid modes we
+             can immediately skip to the next output without having
+             to unwind all the assignments below. */
+          output_get_modes (manager, meta_output, output);
+          if (meta_output->n_modes == 0)
+            continue;
+
+          meta_output->preferred_mode = meta_output->modes[0];
+
          meta_output->winsys_id = resources->outputs[i];
          meta_output->name = g_strdup (output->name);
 
@@ -824,8 +833,6 @@ meta_monitor_manager_xrandr_read_current (MetaMonitorManager *manager)
           meta_output->connector_type = output_get_connector_type (manager_xrandr, meta_output);
 
          output_get_tile_info (manager_xrandr, meta_output);
-         output_get_modes (manager, meta_output, output);
-         meta_output->preferred_mode = meta_output->modes[0];
 
          meta_output->n_possible_crtcs = output->ncrtc;
          meta_output->possible_crtcs = g_new0 (MetaCRTC *, meta_output->n_possible_crtcs);