[mutter/gnome-3-18] monitor-manager-xrandr: Skip outputs with no crtcs

[Rui Matos <rtcm src gnome org>]

commit 8c561a90756aa200f54b1175ae6e292fbb0b957b
Author: Rui Matos <tiagomatos gmail com>
Date:   Tue Oct 27 15:43:58 2015 +0100

    monitor-manager-xrandr: Skip outputs with no crtcs
    
    Outputs with no crtcs shouldn't happen, but if it does we should
    ignore them, instead of possibly crashing later.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=756796

 src/backends/x11/meta-monitor-manager-xrandr.c |   63 ++++++++++++++---------
 1 files changed, 38 insertions(+), 25 deletions(-)
---
diff --git a/src/backends/x11/meta-monitor-manager-xrandr.c b/src/backends/x11/meta-monitor-manager-xrandr.c
index f7e695d..2625620 100644
--- a/src/backends/x11/meta-monitor-manager-xrandr.c
+++ b/src/backends/x11/meta-monitor-manager-xrandr.c
@@ -665,6 +665,42 @@ output_get_modes (MetaMonitorManager *manager,
     meta_output->preferred_mode = meta_output->modes[0];
 }
 
+static void
+output_get_crtcs (MetaMonitorManager *manager,
+                  MetaOutput         *meta_output,
+                  XRROutputInfo      *output)
+{
+  guint j, k;
+  guint n_actual_crtcs;
+
+  meta_output->possible_crtcs = g_new0 (MetaCRTC *, output->ncrtc);
+
+  n_actual_crtcs = 0;
+  for (j = 0; j < (unsigned)output->ncrtc; j++)
+    {
+      for (k = 0; k < manager->n_crtcs; k++)
+        {
+          if ((XID)manager->crtcs[k].crtc_id == output->crtcs[j])
+            {
+              meta_output->possible_crtcs[n_actual_crtcs] = &manager->crtcs[k];
+              n_actual_crtcs += 1;
+              break;
+            }
+        }
+    }
+  meta_output->n_possible_crtcs = n_actual_crtcs;
+
+  meta_output->crtc = NULL;
+  for (j = 0; j < manager->n_crtcs; j++)
+    {
+      if ((XID)manager->crtcs[j].crtc_id == output->crtc)
+        {
+          meta_output->crtc = &manager->crtcs[j];
+          break;
+        }
+    }
+}
+
 static char *
 get_xmode_name (XRRModeInfo *xmode)
 {
@@ -827,30 +863,7 @@ 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->n_possible_crtcs = output->ncrtc;
-         meta_output->possible_crtcs = g_new0 (MetaCRTC *, meta_output->n_possible_crtcs);
-         for (j = 0; j < (unsigned)output->ncrtc; j++)
-           {
-             for (k = 0; k < manager->n_crtcs; k++)
-               {
-                 if ((XID)manager->crtcs[k].crtc_id == output->crtcs[j])
-                   {
-                     meta_output->possible_crtcs[j] = &manager->crtcs[k];
-                     break;
-                   }
-               }
-           }
-
-         meta_output->crtc = NULL;
-         for (j = 0; j < manager->n_crtcs; j++)
-           {
-             if ((XID)manager->crtcs[j].crtc_id == output->crtc)
-               {
-                 meta_output->crtc = &manager->crtcs[j];
-                 break;
-               }
-           }
+          output_get_crtcs (manager, meta_output, output);
 
          meta_output->n_possible_clones = output->nclone;
          meta_output->possible_clones = g_new0 (MetaOutput *, meta_output->n_possible_clones);
@@ -874,7 +887,7 @@ meta_monitor_manager_xrandr_read_current (MetaMonitorManager *manager)
          else
            meta_output->backlight = -1;
 
-          if (meta_output->n_modes == 0)
+          if (meta_output->n_modes == 0 || meta_output->n_possible_crtcs == 0)
             meta_monitor_manager_clear_output (meta_output);
           else
             n_actual_outputs++;