[mutter] monitor-manager-xrandr: Skip outputs with no modes

[Rui Matos <rtcm src gnome org>]

commit 8b200de35ab084a8d61eaa10e2c23bda531a6557
Author: Rui Matos <tiagomatos gmail com>
Date:   Tue Oct 27 15:24:58 2015 +0100

    monitor-manager-xrandr: Skip outputs with no modes
    
    If we can't find any valid modes for an output we need to unwind and
    skip the output because trying to use a modeless output later will
    crash us.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=756796

 src/backends/x11/meta-monitor-manager-xrandr.c |    8 ++++++--
 1 files changed, 6 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..f7e695d 100644
--- a/src/backends/x11/meta-monitor-manager-xrandr.c
+++ b/src/backends/x11/meta-monitor-manager-xrandr.c
@@ -661,6 +661,8 @@ output_get_modes (MetaMonitorManager *manager,
         }
     }
   meta_output->n_modes = n_actual_modes;
+  if (n_actual_modes > 0)
+    meta_output->preferred_mode = meta_output->modes[0];
 }
 
 static char *
@@ -825,7 +827,6 @@ meta_monitor_manager_xrandr_read_current (MetaMonitorManager *manager)
 
          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);
@@ -873,7 +874,10 @@ meta_monitor_manager_xrandr_read_current (MetaMonitorManager *manager)
          else
            meta_output->backlight = -1;
 
-         n_actual_outputs++;
+          if (meta_output->n_modes == 0)
+            meta_monitor_manager_clear_output (meta_output);
+          else
+            n_actual_outputs++;
        }
 
       XRRFreeOutputInfo (output);