[gnome-flashback] monitor-config-store: allow changing D-Bus configuration policy

[Alberts Muktupāvels <muktupavels src gnome org>]

commit c405b17780cbbc6f9ef9c05de59e3388ea048d59
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Mon Mar 7 19:50:16 2022 +0200

    monitor-config-store: allow changing D-Bus configuration policy
    
    Adding a <dbus/> element containing a boolean (yes/no) determines
    whether org.gnome.Mutter.DisplayConfig ApplyMonitorsConfig will be
    callable. The state is also introspectable via the
    ApplyMonitorsConfigAllowed property on the same interface.
    
    For example
    
        <monitors version="2">
          <policy>
            <dbus>no</dbus>
          </policy>
        </monitors>
    
    Based on mutter commit:
    
https://gitlab.gnome.org/GNOME/mutter/-/commit/b49421d8e8c73447872de571620649309e774708#0af849d1b55c8cda122fef9c39eefc5e733c4436

 backends/gf-monitor-config-store-private.h  | 37 +++++++-----
 backends/gf-monitor-config-store.c          | 90 +++++++++++++++++++++++++----
 backends/gf-monitor-manager.c               | 22 +++++++
 backends/org.gnome.Mutter.DisplayConfig.xml |  7 +++
 4 files changed, 131 insertions(+), 25 deletions(-)
---
diff --git a/backends/gf-monitor-config-store-private.h b/backends/gf-monitor-config-store-private.h
index be4bff0..5c866dd 100644
--- a/backends/gf-monitor-config-store-private.h
+++ b/backends/gf-monitor-config-store-private.h
@@ -26,32 +26,39 @@
 
 G_BEGIN_DECLS
 
+typedef struct
+{
+  gboolean enable_dbus;
+} GfMonitorConfigPolicy;
+
 #define GF_TYPE_MONITOR_CONFIG_STORE (gf_monitor_config_store_get_type ())
 G_DECLARE_FINAL_TYPE (GfMonitorConfigStore, gf_monitor_config_store,
                       GF, MONITOR_CONFIG_STORE, GObject)
 
-GfMonitorConfigStore *gf_monitor_config_store_new                 (GfMonitorManager      *monitor_manager);
+GfMonitorConfigStore        *gf_monitor_config_store_new                 (GfMonitorManager      
*monitor_manager);
+
+GfMonitorsConfig            *gf_monitor_config_store_lookup              (GfMonitorConfigStore  
*config_store,
+                                                                          GfMonitorsConfigKey   *key);
 
-GfMonitorsConfig     *gf_monitor_config_store_lookup              (GfMonitorConfigStore  *config_store,
-                                                                   GfMonitorsConfigKey   *key);
+void                         gf_monitor_config_store_add                 (GfMonitorConfigStore  
*config_store,
+                                                                          GfMonitorsConfig      *config);
 
-void                  gf_monitor_config_store_add                 (GfMonitorConfigStore  *config_store,
-                                                                   GfMonitorsConfig      *config);
+void                         gf_monitor_config_store_remove              (GfMonitorConfigStore  
*config_store,
+                                                                          GfMonitorsConfig      *config);
 
-void                  gf_monitor_config_store_remove              (GfMonitorConfigStore  *config_store,
-                                                                   GfMonitorsConfig      *config);
+gboolean                     gf_monitor_config_store_set_custom          (GfMonitorConfigStore  
*config_store,
+                                                                          const gchar           *read_path,
+                                                                          const gchar           *write_path,
+                                                                          GfMonitorsConfigFlag   flags,
+                                                                          GError               **error);
 
-gboolean              gf_monitor_config_store_set_custom          (GfMonitorConfigStore  *config_store,
-                                                                   const gchar           *read_path,
-                                                                   const gchar           *write_path,
-                                                                   GfMonitorsConfigFlag   flags,
-                                                                   GError               **error);
+gint                         gf_monitor_config_store_get_config_count    (GfMonitorConfigStore  
*config_store);
 
-gint                  gf_monitor_config_store_get_config_count    (GfMonitorConfigStore  *config_store);
+GfMonitorManager            *gf_monitor_config_store_get_monitor_manager (GfMonitorConfigStore  
*config_store);
 
-GfMonitorManager     *gf_monitor_config_store_get_monitor_manager (GfMonitorConfigStore  *config_store);
+void                         gf_monitor_config_store_reset               (GfMonitorConfigStore  
*config_store);
 
-void                  gf_monitor_config_store_reset               (GfMonitorConfigStore  *config_store);
+const GfMonitorConfigPolicy *gf_monitor_config_store_get_policy          (GfMonitorConfigStore  
*config_store);
 
 G_END_DECLS
 
diff --git a/backends/gf-monitor-config-store.c b/backends/gf-monitor-config-store.c
index 63d2b02..2bb0aa5 100644
--- a/backends/gf-monitor-config-store.c
+++ b/backends/gf-monitor-config-store.c
@@ -100,20 +100,23 @@
 
 struct _GfMonitorConfigStore
 {
-  GObject           parent;
+  GObject                parent;
 
-  GfMonitorManager *monitor_manager;
+  GfMonitorManager      *monitor_manager;
 
-  GHashTable       *configs;
+  GHashTable            *configs;
 
-  GCancellable     *save_cancellable;
+  GCancellable          *save_cancellable;
 
-  GFile            *user_file;
-  GFile            *custom_read_file;
-  GFile            *custom_write_file;
+  GFile                 *user_file;
+  GFile                 *custom_read_file;
+  GFile                 *custom_write_file;
 
-  gboolean          has_stores_policy;
-  GList            *stores_policy;
+  gboolean               has_stores_policy;
+  GList                 *stores_policy;
+
+  gboolean               has_dbus_policy;
+  GfMonitorConfigPolicy  policy;
 };
 
 enum
@@ -158,7 +161,8 @@ typedef enum
   STATE_DISABLED,
   STATE_POLICY,
   STATE_STORES,
-  STATE_STORE
+  STATE_STORE,
+  STATE_DBUS
 } ParserState;
 
 typedef enum
@@ -190,9 +194,13 @@ typedef struct
 
   gboolean                seen_policy;
   gboolean                seen_stores;
+  gboolean                seen_dbus;
   GfConfigStore           pending_store;
   GList                  *stores;
 
+  gboolean                enable_dbus_set;
+  gboolean                enable_dbus;
+
   ParserState             unknown_state_root;
   int                     unknown_level;
 
@@ -619,6 +627,19 @@ handle_start_element (GMarkupParseContext  *context,
               parser->seen_stores = TRUE;
               parser->state = STATE_STORES;
             }
+          else if (g_str_equal (element_name, "dbus"))
+            {
+              if (parser->seen_dbus)
+                {
+                  g_set_error (error,
+                               G_MARKUP_ERROR, G_MARKUP_ERROR_UNKNOWN_ELEMENT,
+                               "Multiple dbus elements under policy");
+                  return;
+                }
+
+              parser->seen_dbus = TRUE;
+              parser->state = STATE_DBUS;
+            }
           else
             {
               enter_unknown_element (parser,
@@ -654,6 +675,13 @@ handle_start_element (GMarkupParseContext  *context,
           return;
         }
 
+      case STATE_DBUS:
+        {
+          g_set_error (error, G_MARKUP_ERROR, G_MARKUP_ERROR_UNKNOWN_ELEMENT,
+                       "Invalid dbus sub element '%s'", element_name);
+          return;
+        }
+
       default:
         break;
     }
@@ -766,6 +794,7 @@ finish_monitor_spec (ConfigParser *parser)
       case STATE_POLICY:
       case STATE_STORES:
       case STATE_STORE:
+      case STATE_DBUS:
       default:
         g_assert_not_reached ();
         break;
@@ -1029,6 +1058,23 @@ handle_end_element (GMarkupParseContext  *context,
         parser->state = STATE_POLICY;
         return;
 
+      case STATE_DBUS:
+        if (!parser->config_store->has_dbus_policy)
+          {
+            parser->config_store->has_dbus_policy = TRUE;
+            parser->config_store->policy.enable_dbus = parser->enable_dbus;
+            parser->enable_dbus_set = FALSE;
+          }
+        else
+          {
+            g_warning ("Policy for monitor configuration via D-Bus "
+                       "has already been set, ignoring policy from '%s'",
+                       g_file_get_path (parser->file));
+          }
+
+        parser->state = STATE_POLICY;
+        return;
+
       case STATE_POLICY:
         g_assert (g_str_equal (element_name, "policy"));
 
@@ -1362,6 +1408,15 @@ handle_text (GMarkupParseContext  *context,
           return;
         }
 
+      case STATE_DBUS:
+        {
+          parser->enable_dbus_set = TRUE;
+          read_bool (text, text_len,
+                     &parser->enable_dbus,
+                     error);
+          return;
+        }
+
       default:
         break;
     }
@@ -1731,6 +1786,11 @@ gf_monitor_config_store_save (GfMonitorConfigStore *config_store)
       return;
     }
 
+  if (config_store->has_stores_policy &&
+      !g_list_find (config_store->stores_policy,
+                    GINT_TO_POINTER (GF_CONFIG_STORE_USER)))
+    return;
+
   config_store->save_cancellable = g_cancellable_new ();
 
   buffer = generate_config_xml (config_store);
@@ -1875,6 +1935,8 @@ gf_monitor_config_store_init (GfMonitorConfigStore *config_store)
   config_store->configs = g_hash_table_new_full (gf_monitors_config_key_hash,
                                                  gf_monitors_config_key_equal,
                                                  NULL, g_object_unref);
+
+  config_store->policy.enable_dbus = TRUE;
 }
 
 GfMonitorConfigStore *
@@ -1932,6 +1994,8 @@ gf_monitor_config_store_set_custom (GfMonitorConfigStore  *config_store,
 
   g_clear_pointer (&config_store->stores_policy, g_list_free);
   config_store->has_stores_policy = FALSE;
+  config_store->policy.enable_dbus = TRUE;
+  config_store->has_dbus_policy = FALSE;
 
   if (!read_config_file (config_store,
                          config_store->custom_read_file,
@@ -2089,3 +2153,9 @@ gf_monitor_config_store_reset (GfMonitorConfigStore  *config_store)
   g_clear_pointer (&user_configs, g_hash_table_unref);
   g_free (user_file_path);
 }
+
+const GfMonitorConfigPolicy *
+gf_monitor_config_store_get_policy (GfMonitorConfigStore *config_store)
+{
+  return &config_store->policy;
+}
diff --git a/backends/gf-monitor-manager.c b/backends/gf-monitor-manager.c
index 969ac0d..eb41ce3 100644
--- a/backends/gf-monitor-manager.c
+++ b/backends/gf-monitor-manager.c
@@ -33,6 +33,7 @@
 #include "gf-crtc-private.h"
 #include "gf-logical-monitor-private.h"
 #include "gf-monitor-config-manager-private.h"
+#include "gf-monitor-config-store-private.h"
 #include "gf-monitor-manager-private.h"
 #include "gf-monitor-normal-private.h"
 #include "gf-monitor-private.h"
@@ -1989,6 +1990,8 @@ gf_monitor_manager_handle_apply_monitors_config (GfDBusDisplayConfig   *skeleton
                                                  GVariant              *properties_variant,
                                                  GfMonitorManager      *manager)
 {
+  GfMonitorConfigStore *config_store;
+  const GfMonitorConfigPolicy *policy;
   GfMonitorManagerCapability capabilities;
   GVariant *layout_mode_variant;
   GfLogicalMonitorLayoutMode layout_mode;
@@ -2005,6 +2008,17 @@ gf_monitor_manager_handle_apply_monitors_config (GfDBusDisplayConfig   *skeleton
       return TRUE;
     }
 
+  config_store = gf_monitor_config_manager_get_store (manager->config_manager);
+  policy = gf_monitor_config_store_get_policy (config_store);
+
+  if (!policy->enable_dbus)
+    {
+      g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
+                                             G_DBUS_ERROR_ACCESS_DENIED,
+                                             "Monitor configuration via D-Bus is disabled");
+      return TRUE;
+    }
+
   capabilities = gf_monitor_manager_get_capabilities (manager);
   layout_mode_variant = NULL;
   logical_monitor_configs = NULL;
@@ -2465,6 +2479,8 @@ gf_monitor_manager_setup (GfMonitorManager *manager)
 {
   GfMonitorManagerPrivate *priv;
   GfMonitorManagerClass *manager_class;
+  GfMonitorConfigStore *config_store;
+  const GfMonitorConfigPolicy *policy;
 
   priv = gf_monitor_manager_get_instance_private (manager);
   manager_class = GF_MONITOR_MANAGER_GET_CLASS (manager);
@@ -2476,6 +2492,12 @@ gf_monitor_manager_setup (GfMonitorManager *manager)
   gf_monitor_manager_read_current_state (manager);
   manager_class->ensure_initial_config (manager);
 
+  config_store = gf_monitor_config_manager_get_store (manager->config_manager);
+  policy = gf_monitor_config_store_get_policy (config_store);
+
+  gf_dbus_display_config_set_apply_monitors_config_allowed (manager->display_config,
+                                                            policy->enable_dbus);
+
   priv->in_init = FALSE;
 }
 
diff --git a/backends/org.gnome.Mutter.DisplayConfig.xml b/backends/org.gnome.Mutter.DisplayConfig.xml
index 1c6f05b..d0afd23 100644
--- a/backends/org.gnome.Mutter.DisplayConfig.xml
+++ b/backends/org.gnome.Mutter.DisplayConfig.xml
@@ -231,6 +231,13 @@
     -->
     <property name="PanelOrientationManaged" type="b" access="read" />
 
+    <!--
+        ApplyMonitorsConfigAllowed:
+
+        Whether calling the ApplyMonitorsConfig method is allowed.
+    -->
+    <property name="ApplyMonitorsConfigAllowed" type="b" access="read" />
+
     <!--
         MonitorsChanged: