[mutter/wip/xwayland-on-demand: 28/32] Add --no-x11 flag so mutter wayland can be started without X11

[Jonas Ådahl <jadahl src gnome org>]

commit 7d2ef2d8211927f8f487b8fae207d5fdaabbb3c7
Author: Armin Krezović <krezovic armin gmail com>
Date:   Sun Aug 27 20:44:58 2017 +0200

    Add --no-x11 flag so mutter wayland can be started without X11

 src/core/display.c         |   18 +++++++++++++-----
 src/core/main-private.h    |    2 ++
 src/core/main.c            |   26 ++++++++++++++++++++++++++
 src/wayland/meta-wayland.c |    9 +++++++--
 4 files changed, 48 insertions(+), 7 deletions(-)
---
diff --git a/src/core/display.c b/src/core/display.c
index 127d657..79d7689 100644
--- a/src/core/display.c
+++ b/src/core/display.c
@@ -35,6 +35,7 @@
 #include "events.h"
 #include "util-private.h"
 #include <meta/main.h>
+#include "main-private.h"
 #include "window-private.h"
 #include "boxes-private.h"
 #include "frame.h"
@@ -814,12 +815,19 @@ meta_display_open (void)
   display->bell = NULL;
   meta_bell_new (display);
 
-  x11_display = meta_x11_display_new (display, &error);
-  g_assert (x11_display != NULL); /* Required, for now */
-  display->x11_display = x11_display;
-  g_signal_emit (display, display_signals[X11_DISPLAY_OPENED], 0);
+  if (meta_should_autostart_x11_display ())
+    {
+      x11_display = meta_x11_display_new (display, &error);
+      g_assert (x11_display != NULL); /* Required, for now */
+      display->x11_display = x11_display;
+      g_signal_emit (display, display_signals[X11_DISPLAY_OPENED], 0);
 
-  timestamp = display->x11_display->timestamp;
+      timestamp = display->x11_display->timestamp;
+    }
+  else
+    {
+      timestamp = meta_display_get_current_time_roundtrip (display);
+    }
 
   display->last_focus_time = timestamp;
   display->last_user_time = timestamp;
diff --git a/src/core/main-private.h b/src/core/main-private.h
index 36f4b31..e59b766 100644
--- a/src/core/main-private.h
+++ b/src/core/main-private.h
@@ -31,4 +31,6 @@ typedef enum _MetaCompositorType
 void meta_override_compositor_configuration (MetaCompositorType compositor_type,
                                              GType              backend_gtype);
 
+gboolean meta_should_autostart_x11_display (void);
+
 #endif /* META_MAIN_PRIVATE_H */
diff --git a/src/core/main.c b/src/core/main.c
index c3632b5..82fcf75 100644
--- a/src/core/main.c
+++ b/src/core/main.c
@@ -177,6 +177,7 @@ static gboolean  opt_sync;
 #ifdef HAVE_WAYLAND
 static gboolean  opt_wayland;
 static gboolean  opt_nested;
+static gboolean  opt_no_x11;
 #endif
 #ifdef HAVE_NATIVE_BACKEND
 static gboolean  opt_display_server;
@@ -231,6 +232,12 @@ static GOptionEntry meta_options[] = {
     N_("Run as a nested compositor"),
     NULL
   },
+  {
+    "no-x11", 0, 0, G_OPTION_ARG_NONE,
+    &opt_no_x11,
+    N_("Run wayland compositor without starting Xwayland"),
+    NULL
+  },
 #endif
 #ifdef HAVE_NATIVE_BACKEND
   {
@@ -437,6 +444,12 @@ calculate_compositor_configuration (MetaCompositorType *compositor_type,
     run_as_wayland_compositor = check_for_wayland_session_type ();
 #endif /* HAVE_NATIVE_BACKEND */
 
+  if (!run_as_wayland_compositor && opt_no_x11)
+    {
+      meta_warning ("Can't disable X11 support on X11 compositor\n");
+      meta_exit (META_EXIT_ERROR);
+    }
+
   if (run_as_wayland_compositor)
     *compositor_type = META_COMPOSITOR_TYPE_WAYLAND;
   else
@@ -693,3 +706,16 @@ prefs_changed_callback (MetaPreference pref,
       break;
     }
 }
+
+gboolean
+meta_should_autostart_x11_display (void)
+{
+  MetaBackend *backend = meta_get_backend ();
+  gboolean is_x11 = TRUE;
+
+#ifdef HAVE_WAYLAND
+  is_x11 = !opt_no_x11;
+#endif
+
+  return META_IS_BACKEND_X11_CM (backend) || is_x11;
+}
diff --git a/src/wayland/meta-wayland.c b/src/wayland/meta-wayland.c
index 414c7fb..dd48b52 100644
--- a/src/wayland/meta-wayland.c
+++ b/src/wayland/meta-wayland.c
@@ -45,6 +45,8 @@
 #include "meta-wayland-inhibit-shortcuts.h"
 #include "meta-wayland-inhibit-shortcuts-dialog.h"
 
+#include "main-private.h"
+
 static MetaWaylandCompositor _meta_wayland_compositor;
 static char *_display_name_override;
 
@@ -362,7 +364,8 @@ meta_wayland_init (void)
   meta_wayland_keyboard_shortcuts_inhibit_init (compositor);
   meta_wayland_surface_inhibit_shortcuts_dialog_init ();
 
-  if (!meta_xwayland_start (&compositor->xwayland_manager, compositor->wayland_display))
+  if (meta_should_autostart_x11_display () &&
+      !meta_xwayland_start (&compositor->xwayland_manager, compositor->wayland_display))
     g_error ("Failed to start X Wayland");
 
   if (_display_name_override)
@@ -383,7 +386,9 @@ meta_wayland_init (void)
         g_error ("Failed to create socket");
     }
 
-  set_gnome_env ("DISPLAY", meta_wayland_get_xwayland_display_name (compositor));
+  if (meta_should_autostart_x11_display ())
+    set_gnome_env ("DISPLAY", meta_wayland_get_xwayland_display_name (compositor));
+
   set_gnome_env ("WAYLAND_DISPLAY", meta_wayland_get_wayland_display_name (compositor));
 }