daemon: Provide more flexibility for configuring display server

There's currently a way to disable wayland, but no way to disable Xorg.
We currently prefer wayland if it's not disabled, but have no way to
prefer Xorg without disabling wayland entirely.

There's currently no way use legacy Xorg support at all if user display
server support is enabled at a build time.

This commit adds more flexibility to display server selection. It adds
two new keys: XorgEnable and and PreferredDisplayServer.

XorgEnable=false disables Xorg support entirely on seat 0.

PreferredDisplayServer can be set to "wayland", "xorg", "legacy-xorg" or
"none" to select which display server is used by default. If it's set to
"wayland", it will fall back to "xorg". If it's set to "xorg" it will
fall back to "wayland".

1 files changed, 36 insertions, 0 deletions

diff --git a/daemon/gdm-display.c b/daemon/gdm-display.c
index 3a260923..46d5a773 100644
--- a/daemon/gdm-display.c
+++ b/daemon/gdm-display.c
@@ -93,6 +93,8 @@ typedef struct _GdmDisplayPrivate
         guint                 have_existing_user_accounts : 1;
         guint                 doing_initial_setup : 1;
         guint                 session_registered : 1;
+
+        GStrv                 supported_session_types;
 } GdmDisplayPrivate;
 
 enum {
@@ -116,6 +118,7 @@ enum {
         PROP_HAVE_EXISTING_USER_ACCOUNTS,
         PROP_DOING_INITIAL_SETUP,
         PROP_SESSION_REGISTERED,
+        PROP_SUPPORTED_SESSION_TYPES,
 };
 
 static void     gdm_display_class_init  (GdmDisplayClass *klass);
@@ -911,6 +914,23 @@ _gdm_display_set_allow_timed_login (GdmDisplay     *self,
 }
 
 static void
+_gdm_display_set_supported_session_types (GdmDisplay         *self,
+                                          const char * const *supported_session_types)
+
+{
+        GdmDisplayPrivate *priv;
+        g_autofree char *supported_session_types_string = NULL;
+
+	if (supported_session_types != NULL)
+          supported_session_types_string = g_strjoinv (":", (GStrv) supported_session_types);
+
+        priv = gdm_display_get_instance_private (self);
+        g_debug ("GdmDisplay: supported session types: %s", supported_session_types_string);
+        g_strfreev (priv->supported_session_types);
+        priv->supported_session_types = g_strdupv ((GStrv) supported_session_types);
+}
+
+static void
 gdm_display_set_property (GObject        *object,
                           guint           prop_id,
                           const GValue   *value,
@@ -966,6 +986,9 @@ gdm_display_set_property (GObject        *object,
         case PROP_SESSION_REGISTERED:
                 _gdm_display_set_session_registered (self, g_value_get_boolean (value));
                 break;
+        case PROP_SUPPORTED_SESSION_TYPES:
+                _gdm_display_set_supported_session_types (self, g_value_get_boxed (value));
+                break;
         default:
                 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
                 break;
@@ -1044,6 +1067,9 @@ gdm_display_get_property (GObject        *object,
         case PROP_ALLOW_TIMED_LOGIN:
                 g_value_set_boolean (value, priv->allow_timed_login);
                 break;
+        case PROP_SUPPORTED_SESSION_TYPES:
+                g_value_set_boxed (value, priv->supported_session_types);
+                break;
         default:
                 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
                 break;
@@ -1229,6 +1255,7 @@ gdm_display_dispose (GObject *object)
                 priv->finish_idle_id = 0;
         }
         g_clear_object (&priv->launch_environment);
+        g_clear_pointer (&priv->supported_session_types, g_strfreev);
 
         g_warn_if_fail (priv->status != GDM_DISPLAY_MANAGED);
         g_warn_if_fail (priv->user_access_file == NULL);
@@ -1389,6 +1416,14 @@ gdm_display_class_init (GdmDisplayClass *klass)
                                                            G_MAXINT,
                                                            GDM_DISPLAY_UNMANAGED,
                                                            G_PARAM_READWRITE | G_PARAM_CONSTRUCT | G_PARAM_STATIC_STRINGS));
+
+        g_object_class_install_property (object_class,
+                                         PROP_SUPPORTED_SESSION_TYPES,
+                                         g_param_spec_boxed ("supported-session-types",
+                                                             "supported session types",
+                                                             "supported session types",
+                                                             G_TYPE_STRV,
+                                                             G_PARAM_READWRITE | G_PARAM_CONSTRUCT | G_PARAM_STATIC_STRINGS));
 }
 
 static void
@@ -1721,6 +1756,7 @@ gdm_display_start_greeter_session (GdmDisplay *self)
         session = gdm_launch_environment_get_session (priv->launch_environment);
         g_object_set (G_OBJECT (session),
                       "display-is-initial", priv->is_initial,
+                      "supported-session-types", priv->supported_session_types,
                       NULL);
 
         g_free (display_name);