[mutter] monitor-config: Prevent a crash applying config for a closed lid

[Rui Matos <rtcm src gnome org>]

commit 3b1271d9be8a5603f3d52cc5b5f31958623f391c
Author: Rui Matos <tiagomatos gmail com>
Date:   Fri Oct 31 15:02:05 2014 +0100

    monitor-config: Prevent a crash applying config for a closed lid
    
    When a laptop's lid is closed we try to build and apply a temporary
    configuration that disables the laptop's display if we have other
    outputs.
    
    This isn't enough though, we must also check if at least one of these
    other outputs is enabled otherwise we'll try to resize the screen to
    0x0 which (rightfully) hits an assertion.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=739450

 src/backends/meta-monitor-config.c |   19 ++++++++++++++++---
 1 files changed, 16 insertions(+), 3 deletions(-)
---
diff --git a/src/backends/meta-monitor-config.c b/src/backends/meta-monitor-config.c
index a421761..98ae220 100644
--- a/src/backends/meta-monitor-config.c
+++ b/src/backends/meta-monitor-config.c
@@ -914,6 +914,19 @@ laptop_display_is_on (MetaConfiguration *config)
   return FALSE;
 }
 
+static gboolean
+multiple_outputs_are_enabled (MetaConfiguration *config)
+{
+  unsigned int i, enabled;
+
+  enabled = 0;
+  for (i = 0; i < config->n_outputs; i++)
+    if (config->outputs[i].enabled)
+      enabled++;
+
+  return enabled > 1;
+}
+
 static MetaConfiguration *
 make_laptop_lid_config (MetaConfiguration  *reference)
 {
@@ -923,7 +936,7 @@ make_laptop_lid_config (MetaConfiguration  *reference)
   int x_after, y_after;
   int x_offset, y_offset;
 
-  g_assert (reference->n_outputs > 1);
+  g_assert (multiple_outputs_are_enabled (reference));
 
   new = config_new ();
   new->n_outputs = reference->n_outputs;
@@ -986,7 +999,7 @@ apply_configuration_with_lid (MetaMonitorConfig  *self,
                               MetaMonitorManager *manager)
 {
   if (self->lid_is_closed &&
-      config->n_outputs > 1 &&
+      multiple_outputs_are_enabled (config) &&
       laptop_display_is_on (config))
     {
       MetaConfiguration *laptop_lid_config = make_laptop_lid_config (config);
@@ -1353,7 +1366,7 @@ turn_off_laptop_display (MetaMonitorConfig  *self,
 {
   MetaConfiguration *new;
 
-  if (self->current->n_outputs == 1)
+  if (!multiple_outputs_are_enabled (self->current))
     return;
 
   new = make_laptop_lid_config (self->current);