[gnome-control-center/gnome-3-32] display: Add failure returns into CcDisplayConfig

[Benjamin Berg <bberg src gnome org>]

commit e9aa94df02b366e9f90b0b742b1b367f2816eec4
Author: Benjamin Berg <bberg redhat com>
Date:   Wed Jul 3 09:52:42 2019 +0200

    display: Add failure returns into CcDisplayConfig
    
    This guards against accidental use of NULL pointers so that the panel
    will hopefully not crash if new bugs like this are introduced.
    
    (cherry picked from commit 561ac849d733545f73f2d3fd9ee8c530f3174129)

 panels/display/cc-display-config-dbus.c |  3 +++
 panels/display/cc-display-config.c      | 25 +++++++++++++++++++++++++
 2 files changed, 28 insertions(+)
---
diff --git a/panels/display/cc-display-config-dbus.c b/panels/display/cc-display-config-dbus.c
index 2615461ea..891125409 100644
--- a/panels/display/cc-display-config-dbus.c
+++ b/panels/display/cc-display-config-dbus.c
@@ -1052,6 +1052,9 @@ cc_display_config_dbus_equal (CcDisplayConfig *pself,
   CcDisplayConfigDBus *other = CC_DISPLAY_CONFIG_DBUS (pother);
   GList *l;
 
+  g_return_val_if_fail (pself, FALSE);
+  g_return_val_if_fail (pother, FALSE);
+
   cc_display_config_dbus_ensure_non_offset_coords (self);
   cc_display_config_dbus_ensure_non_offset_coords (other);
 
diff --git a/panels/display/cc-display-config.c b/panels/display/cc-display-config.c
index 3bed67a49..2c1c62499 100644
--- a/panels/display/cc-display-config.c
+++ b/panels/display/cc-display-config.c
@@ -17,6 +17,7 @@
  *
  */
 
+#include <gio/gio.h>
 #include <math.h>
 #include "cc-display-config.h"
 
@@ -480,12 +481,14 @@ cc_display_config_class_init (CcDisplayConfigClass *klass)
 GList *
 cc_display_config_get_monitors (CcDisplayConfig *self)
 {
+  g_return_val_if_fail (CC_IS_DISPLAY_CONFIG (self), NULL);
   return CC_DISPLAY_CONFIG_GET_CLASS (self)->get_monitors (self);
 }
 
 GList *
 cc_display_config_get_ui_sorted_monitors (CcDisplayConfig *self)
 {
+  g_return_val_if_fail (CC_IS_DISPLAY_CONFIG (self), NULL);
   return CC_DISPLAY_CONFIG_GET_PRIVATE (self)->ui_sorted_monitors;
 }
 
@@ -496,6 +499,8 @@ cc_display_config_count_useful_monitors (CcDisplayConfig *self)
   GList *outputs, *l;
   guint count = 0;
 
+  g_return_val_if_fail (CC_IS_DISPLAY_CONFIG (self), 0);
+
   outputs = priv->ui_sorted_monitors;
   for (l = outputs; l != NULL; l = l->next)
     {
@@ -512,6 +517,7 @@ cc_display_config_count_useful_monitors (CcDisplayConfig *self)
 gboolean
 cc_display_config_is_applicable (CcDisplayConfig *self)
 {
+  g_return_val_if_fail (CC_IS_DISPLAY_CONFIG (self), FALSE);
   return CC_DISPLAY_CONFIG_GET_CLASS (self)->is_applicable (self);
 }
 
@@ -521,6 +527,8 @@ cc_display_config_set_mode_on_all_outputs (CcDisplayConfig *config,
 {
   GList *outputs, *l;
 
+  g_return_if_fail (CC_IS_DISPLAY_CONFIG (config));
+
   outputs = cc_display_config_get_monitors (config);
   for (l = outputs; l; l = l->next)
     {
@@ -534,6 +542,9 @@ gboolean
 cc_display_config_equal (CcDisplayConfig *self,
                          CcDisplayConfig *other)
 {
+  g_return_val_if_fail (CC_IS_DISPLAY_CONFIG (self), FALSE);
+  g_return_val_if_fail (CC_IS_DISPLAY_CONFIG (other), FALSE);
+
   return CC_DISPLAY_CONFIG_GET_CLASS (self)->equal (self, other);
 }
 
@@ -541,12 +552,23 @@ gboolean
 cc_display_config_apply (CcDisplayConfig *self,
                          GError **error)
 {
+  if (!CC_IS_DISPLAY_CONFIG (self))
+    {
+      g_warning ("Cannot apply invalid configuration");
+      g_set_error (error,
+                   G_IO_ERROR,
+                   G_IO_ERROR_FAILED,
+                   "Cannot apply invalid configuration");
+      return FALSE;
+    }
+
   return CC_DISPLAY_CONFIG_GET_CLASS (self)->apply (self, error);
 }
 
 gboolean
 cc_display_config_is_cloning (CcDisplayConfig *self)
 {
+  g_return_val_if_fail (CC_IS_DISPLAY_CONFIG (self), FALSE);
   return CC_DISPLAY_CONFIG_GET_CLASS (self)->is_cloning (self);
 }
 
@@ -554,17 +576,20 @@ void
 cc_display_config_set_cloning (CcDisplayConfig *self,
                                gboolean clone)
 {
+  g_return_if_fail (CC_IS_DISPLAY_CONFIG (self));
   return CC_DISPLAY_CONFIG_GET_CLASS (self)->set_cloning (self, clone);
 }
 
 GList *
 cc_display_config_get_cloning_modes (CcDisplayConfig *self)
 {
+  g_return_val_if_fail (CC_IS_DISPLAY_CONFIG (self), NULL);
   return CC_DISPLAY_CONFIG_GET_CLASS (self)->get_cloning_modes (self);
 }
 
 gboolean
 cc_display_config_is_layout_logical (CcDisplayConfig *self)
 {
+  g_return_val_if_fail (CC_IS_DISPLAY_CONFIG (self), FALSE);
   return CC_DISPLAY_CONFIG_GET_CLASS (self)->is_layout_logical (self);
 }