xwayland: add wlr_xwayland_server_options.terminate_delay

This allows users to specify a delay after which the Xwayland process
terminates itself when there are no more X11 clients connected.

include/wlr/xwayland.h

@@ -24,6 +24,7 @@ struct wlr_xwayland_server_options {
 	bool lazy;
 	bool enable_wm;
 	bool no_touch_pointer_emulation;
+	int terminate_delay; // in seconds, 0 to terminate immediately
 };
 
 struct wlr_xwayland_server {

include/xwayland/meson.build

@@ -1,11 +1,13 @@
 have_listenfd = false
 have_no_touch_pointer_emulation = false
+have_terminate_delay = false
 if xwayland.found()
 	xwayland_path = xwayland.get_variable('xwayland')
 	have_listenfd = xwayland.get_variable('have_listenfd',
 		default_value: 'false') == 'true'
 	have_no_touch_pointer_emulation = xwayland.get_variable(
 		'have_no_touch_pointer_emulation', default_value: 'false') == 'true'
+	have_terminate_delay = xwayland.get_variable(pkgconfig: 'have_terminate_delay') == 'true'
 else
 	xwayland_path = xwayland_prog.full_path()
 endif
@@ -14,6 +16,7 @@ xwayland_config_data = configuration_data()
 xwayland_config_data.set_quoted('XWAYLAND_PATH', xwayland_path)
 xwayland_config_data.set10('HAVE_XWAYLAND_LISTENFD', have_listenfd)
 xwayland_config_data.set10('HAVE_XWAYLAND_NO_TOUCH_POINTER_EMULATION', have_no_touch_pointer_emulation)
+xwayland_config_data.set10('HAVE_XWAYLAND_TERMINATE_DELAY', have_terminate_delay)
 configure_file(
 	output: 'config.h',
 	configuration: xwayland_config_data,

xwayland/server.c

@@ -49,9 +49,18 @@ noreturn static void exec_xwayland(struct wlr_xwayland_server *server,
 	argv[i++] = "Xwayland";
 	argv[i++] = server->display_name;
 	argv[i++] = "-rootless";
-	argv[i++] = "-terminate";
 	argv[i++] = "-core";
 
+	argv[i++] = "-terminate";
+#if HAVE_XWAYLAND_TERMINATE_DELAY
+	char terminate_delay[16];
+	if (server->options.terminate_delay > 0) {
+		snprintf(terminate_delay, sizeof(terminate_delay), "%d",
+			server->options.terminate_delay);
+		argv[i++] = terminate_delay;
+	}
+#endif
+
 #if HAVE_XWAYLAND_LISTENFD
 	argv[i++] = "-listenfd";
 	argv[i++] = listenfd0;
@@ -436,6 +445,10 @@ struct wlr_xwayland_server *wlr_xwayland_server_create(
 	server->wl_display = wl_display;
 	server->options = *options;
 
+#if !HAVE_XWAYLAND_TERMINATE_DELAY
+	server->options.terminate_delay = 0;
+#endif
+
 	server->x_fd[0] = server->x_fd[1] = -1;
 	server->wl_fd[0] = server->wl_fd[1] = -1;
 	server->wm_fd[0] = server->wm_fd[1] = -1;