main: Make it possible to set properties when overriding configuration

This makes it possible to pass custom properties to backends when
constructing tests. This will be used to create "headless" native
backend instances for testing the headless native backend.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1698>

src/core/main-private.h

@@ -47,7 +47,9 @@ typedef enum _MetaDisplayPolicy
 
 META_EXPORT_TEST
 void meta_override_compositor_configuration (MetaCompositorType compositor_type,
-                                             GType              backend_gtype);
+                                             GType              backend_gtype,
+                                             const char        *first_property_name,
+                                             ...);
 
 META_EXPORT_TEST
 MetaDisplayPolicy meta_get_x11_display_policy (void);

src/core/main.c

@@ -51,6 +51,7 @@
 #include <fcntl.h>
 #include <glib-object.h>
 #include <glib-unix.h>
+#include <gobject/gvaluecollector.h>
 #include <locale.h>
 #include <signal.h>
 #include <stdio.h>
@@ -581,14 +582,61 @@ calculate_compositor_configuration (MetaCompositorType  *compositor_type,
 static gboolean _compositor_configuration_overridden = FALSE;
 static MetaCompositorType _compositor_type_override;
 static GType _backend_gtype_override;
+static GArray *_backend_property_names;
+static GArray *_backend_property_values;
 
 void
 meta_override_compositor_configuration (MetaCompositorType compositor_type,
-                                        GType              backend_gtype)
+                                        GType              backend_gtype,
+                                        const char        *first_property_name,
+                                        ...)
 {
+  va_list var_args;
+  GArray *names;
+  GArray *values;
+  GObjectClass *object_class;
+  const char *property_name;
+
+  names = g_array_new (FALSE, FALSE, sizeof (const char *));
+  values = g_array_new (FALSE, FALSE, sizeof (GValue));
+  g_array_set_clear_func (values, (GDestroyNotify) g_value_unset);
+
+  object_class = g_type_class_ref (backend_gtype);
+
+  property_name = first_property_name;
+
+  va_start (var_args, first_property_name);
+
+  while (property_name)
+    {
+      GValue value = G_VALUE_INIT;
+      GParamSpec *pspec;
+      GType ptype;
+      char *error = NULL;
+
+      pspec = g_object_class_find_property (object_class,
+                                            property_name);
+      g_assert (pspec);
+
+      ptype = G_PARAM_SPEC_VALUE_TYPE (pspec);
+      G_VALUE_COLLECT_INIT (&value, ptype, var_args, 0, &error);
+      g_assert (!error);
+
+      g_array_append_val (names, property_name);
+      g_array_append_val (values, value);
+
+      property_name = va_arg (var_args, const char *);
+    }
+
+  va_end (var_args);
+
+  g_type_class_unref (object_class);
+
   _compositor_configuration_overridden = TRUE;
   _compositor_type_override = compositor_type;
   _backend_gtype_override = backend_gtype;
+  _backend_property_names = names;
+  _backend_property_values = values;
 }
 
 /**
@@ -647,9 +695,9 @@ meta_init (void)
     {
       compositor_type = _compositor_type_override;
       backend_gtype = _backend_gtype_override;
-      n_properties = 0;
+      n_properties = _backend_property_names->len;
-      prop_names = NULL;
+      prop_names = (const char **) _backend_property_names->data;
-      prop_values = NULL;
+      prop_values = (GValue *) _backend_property_values->data;
     }
   else
     {
@@ -693,6 +741,12 @@ meta_init (void)
   for (i = 0; i < n_properties; i++)
     g_value_reset (&prop_values[i]);
 
+  if (_backend_property_names)
+    {
+      g_array_free (_backend_property_names, TRUE);
+      g_array_free (_backend_property_values, TRUE);
+    }
+
   meta_set_syncing (opt_sync || (g_getenv ("MUTTER_SYNC") != NULL));
 
   if (opt_replace_wm)
@@ -864,7 +918,8 @@ meta_test_init (void)
   int fd = g_mkstemp (display_name);
 
   meta_override_compositor_configuration (META_COMPOSITOR_TYPE_WAYLAND,
-                                          META_TYPE_BACKEND_X11_NESTED);
+                                          META_TYPE_BACKEND_X11_NESTED,
+                                          NULL);
   meta_wayland_override_display_name (display_name);
   meta_xwayland_override_display_number (512 + rand() % 512);
   meta_init ();

src/tests/clutter/interactive/test-main.c

@@ -129,7 +129,8 @@ main (int argc, char **argv)
   meta_wayland_override_display_name ("mutter-test-display");
   meta_xwayland_override_display_number (512);
   meta_override_compositor_configuration (META_COMPOSITOR_TYPE_WAYLAND,
-                                          META_TYPE_BACKEND_X11_NESTED);
+                                          META_TYPE_BACKEND_X11_NESTED,
+                                          NULL);
   meta_init ();
 
   module = g_module_open (NULL, 0);

src/tests/headless-start-test.c

@@ -217,7 +217,8 @@ main (int argc, char *argv[])
   meta_plugin_manager_load (test_get_plugin_name ());
 
   meta_override_compositor_configuration (META_COMPOSITOR_TYPE_WAYLAND,
-                                          META_TYPE_BACKEND_TEST);
+                                          META_TYPE_BACKEND_TEST,
+                                          NULL);
 
   meta_init ();
   meta_register_with_session ();

src/tests/stage-view-tests.c

@@ -1192,7 +1192,8 @@ main (int argc, char *argv[])
   meta_plugin_manager_load (test_get_plugin_name ());
 
   meta_override_compositor_configuration (META_COMPOSITOR_TYPE_WAYLAND,
-                                          META_TYPE_BACKEND_TEST);
+                                          META_TYPE_BACKEND_TEST,
+                                          NULL);
 
   meta_init ();
   meta_register_with_session ();

src/tests/unit-tests.c

@@ -269,7 +269,8 @@ main (int argc, char *argv[])
   meta_plugin_manager_load (test_get_plugin_name ());
 
   meta_override_compositor_configuration (META_COMPOSITOR_TYPE_WAYLAND,
-                                          META_TYPE_BACKEND_TEST);
+                                          META_TYPE_BACKEND_TEST,
+                                          NULL);
 
   meta_init ();
   meta_register_with_session ();