launcher: Add back support for specifying VT to run on

This is only available when running weston directly as root typically for
ssh logins.  It's a somewhat destructive option, as it will take over any
existing VT completely, unless there's already an display server running
there.

https://bugs.freedesktop.org/show_bug.cgi?id=69731

src/compositor-drm.c

@@ -2564,7 +2564,7 @@ drm_compositor_create(struct wl_display *display,
 	}
 
 	/* Check if we run drm-backend using weston-launch */
-	ec->base.launcher = weston_launcher_connect(&ec->base);
+	ec->base.launcher = weston_launcher_connect(&ec->base, tty);
 	if (ec->base.launcher == NULL) {
 		weston_log("fatal: drm backend should be run "
 			   "using weston-launch binary or as root\n");

src/compositor-fbdev.c

@@ -880,7 +880,8 @@ fbdev_compositor_create(struct wl_display *display, int *argc, char *argv[],
 		goto out_free;
 
 	/* Check if we run fbdev-backend using weston-launch */
-	compositor->base.launcher = weston_launcher_connect(&compositor->base);
+	compositor->base.launcher =
+		weston_launcher_connect(&compositor->base, param->tty);
 	if (compositor->base.launcher == NULL && geteuid() != 0) {
 		weston_log("fatal: fbdev backend should be run "
 			   "using weston-launch binary or as root\n");
@@ -897,7 +898,8 @@ fbdev_compositor_create(struct wl_display *display, int *argc, char *argv[],
 	compositor->session_listener.notify = session_notify;
 	wl_signal_add(&compositor->base.session_signal,
 		      &compositor->session_listener);
-	compositor->base.launcher = weston_launcher_connect(&compositor->base);
+	compositor->base.launcher =
+		weston_launcher_connect(&compositor->base, param->tty);
 	if (!compositor->base.launcher) {
 		weston_log("Failed to set up launcher.\n");
 		goto out_udev;

src/compositor-rpi.c

@@ -751,7 +751,8 @@ rpi_compositor_create(struct wl_display *display, int *argc, char *argv[],
 	compositor->session_listener.notify = session_notify;
 	wl_signal_add(&compositor->base.session_signal,
 		      &compositor ->session_listener);
-	compositor->base.launcher = weston_launcher_connect(&compositor->base);
+	compositor->base.launcher =
+		weston_launcher_connect(&compositor->base, param->tty);
 	if (!compositor->base.launcher) {
 		weston_log("Failed to initialize tty.\n");
 		goto out_udev;

src/launcher-util.c

@@ -247,22 +247,50 @@ vt_handler(int signal_number, void *data)
 }
 
 static int
-setup_tty(struct weston_launcher *launcher)
+setup_tty(struct weston_launcher *launcher, int tty)
 {
 	struct wl_event_loop *loop;
 	struct vt_mode mode = { 0 };
 	struct stat buf;
-	int ret;
+	char tty_device[32] ="<stdin>";
+	int ret, kd_mode;
 
-	if (fstat(STDIN_FILENO, &buf) == -1 ||
+	if (tty == 0) {
+		launcher->tty = tty;
+	} else {
+		snprintf(tty_device, sizeof tty_device, "/dev/tty%d", tty);
+		launcher->tty = open(tty_device, O_RDWR | O_CLOEXEC);
+		if (launcher->tty == -1) {
+			weston_log("couldn't open tty %s: %m\n", tty_device);
+			return -1;
+		}
+	}
+
+	if (fstat(launcher->tty, &buf) == -1 ||
 	    major(buf.st_rdev) != TTY_MAJOR || minor(buf.st_rdev) == 0) {
-		weston_log("stdin not a vt\n");
+		weston_log("%s not a vt\n", tty_device);
 		weston_log("if running weston from ssh, "
 			   "use --tty to specify a tty\n");
 		return -1;
 	}
 
-	launcher->tty = STDIN_FILENO;
+	ret = ioctl(launcher->tty, KDGETMODE, &kd_mode);
+	if (ret) {
+		weston_log("failed to get VT mode: %m\n");
+		return -1;
+	}
+	if (kd_mode != KD_TEXT) {
+		weston_log("%s is already in graphics mode, "
+			   "is another display server running?\n", tty_device);
+		return -1;
+	}
+
+	ret = ioctl(launcher->tty, VT_ACTIVATE, minor(buf.st_rdev));
+	weston_log("VT_ACTIVATE ret=%d, %m vt\n", ret);
+
+	ret = ioctl(launcher->tty, VT_WAITACTIVE, minor(buf.st_rdev));
+	weston_log("VT_WAITACTIVE ret=%d, %m vt\n", ret);
+
 	if (ioctl(launcher->tty, KDGKBMODE, &launcher->kb_mode)) {
 		weston_log("failed to read keyboard mode: %m\n");
 		return -1;
@@ -304,7 +332,7 @@ weston_launcher_activate_vt(struct weston_launcher *launcher, int vt)
 }
 
 struct weston_launcher *
-weston_launcher_connect(struct weston_compositor *compositor)
+weston_launcher_connect(struct weston_compositor *compositor, int tty)
 {
 	struct weston_launcher *launcher;
 	struct wl_event_loop *loop;
@@ -328,7 +356,7 @@ weston_launcher_connect(struct weston_compositor *compositor)
 			return NULL;
 		}
 	} else if (geteuid() == 0) {
-		if (setup_tty(launcher) == -1) {
+		if (setup_tty(launcher, tty) == -1) {
 			free(launcher);
 			return NULL;
 		}

src/launcher-util.h

@@ -30,7 +30,7 @@
 struct weston_launcher;
 
 struct weston_launcher *
-weston_launcher_connect(struct weston_compositor *compositor);
+weston_launcher_connect(struct weston_compositor *compositor, int tty);
 
 void
 weston_launcher_destroy(struct weston_launcher *launcher);