compositor-drm: Add proper error handling to init

This way, if initialisation fails (say, udev or Mesa are broken, or we
couldn't find any devices), we'll at least take you back to where you
were, rather than leave you at a totally broken VT you can't escape
from.

Signed-off-by: Daniel Stone <daniel@fooishbar.org>

src/compositor-drm.c

@@ -1767,6 +1767,7 @@ drm_compositor_create(struct wl_display *display,
 	struct udev_device *device, *drm_device;
 	const char *path, *device_seat;
 	struct wl_event_loop *loop;
+	struct weston_seat *weston_seat, *next;
 	uint32_t key;
 
 	weston_log("initializing drm backend\n");
@@ -1777,21 +1778,22 @@ drm_compositor_create(struct wl_display *display,
 	memset(ec, 0, sizeof *ec);
 
 	if (weston_compositor_init(&ec->base, display, argc, argv,
-				   config_file) < 0)
-		return NULL;
+				   config_file) < 0) {
+		weston_log("weston_compositor_init failed\n");
+		goto err_base;
+	}
 
 	ec->udev = udev_new();
 	if (ec->udev == NULL) {
 		weston_log("failed to initialize udev context\n");
-		return NULL;
+		goto err_compositor;
 	}
 
 	ec->base.wl_display = display;
 	ec->tty = tty_create(&ec->base, vt_func, tty);
 	if (!ec->tty) {
 		weston_log("failed to initialize tty\n");
-		free(ec);
-		return NULL;
+		goto err_udev;
 	}
 
 	e = udev_enumerate_new(ec->udev);
@@ -1816,12 +1818,12 @@ drm_compositor_create(struct wl_display *display,
 
 	if (drm_device == NULL) {
 		weston_log("no drm device found\n");
-		return NULL;
+		goto err_udev_enum;
 	}
 
 	if (init_egl(ec, drm_device) < 0) {
 		weston_log("failed to initialize egl\n");
-		return NULL;
+		goto err_udev_dev;
 	}
 
 	ec->base.destroy = drm_destroy;
@@ -1831,7 +1833,7 @@ drm_compositor_create(struct wl_display *display,
 	ec->prev_state = WESTON_COMPOSITOR_ACTIVE;
 
 	if (weston_compositor_init_gl(&ec->base) < 0)
-		return NULL;
+		goto err_egl;
 
 	for (key = KEY_F1; key < KEY_F9; key++)
 		weston_compositor_add_key_binding(&ec->base, key,
@@ -1843,11 +1845,9 @@ drm_compositor_create(struct wl_display *display,
 
 	if (create_outputs(ec, connector, drm_device) < 0) {
 		weston_log("failed to create output for %s\n", path);
-		return NULL;
+		goto err_sprite;
 	}
 
-	udev_device_unref(drm_device);
-	udev_enumerate_unref(e);
 	path = NULL;
 
 	evdev_input_create(&ec->base, ec->udev, seat);
@@ -1860,7 +1860,7 @@ drm_compositor_create(struct wl_display *display,
 	ec->udev_monitor = udev_monitor_new_from_netlink(ec->udev, "udev");
 	if (ec->udev_monitor == NULL) {
 		weston_log("failed to intialize udev monitor\n");
-		return NULL;
+		goto err_drm_source;
 	}
 	udev_monitor_filter_add_match_subsystem_devtype(ec->udev_monitor,
 							"drm", NULL);
@@ -1871,10 +1871,41 @@ drm_compositor_create(struct wl_display *display,
 
 	if (udev_monitor_enable_receiving(ec->udev_monitor) < 0) {
 		weston_log("failed to enable udev-monitor receiving\n");
-		return NULL;
+		goto err_udev_monitor;
 	}
 
+	udev_device_unref(drm_device);
+	udev_enumerate_unref(e);
+
 	return &ec->base;
+
+err_udev_monitor:
+	wl_event_source_remove(ec->udev_drm_source);
+	udev_monitor_unref(ec->udev_monitor);
+err_drm_source:
+	wl_event_source_remove(ec->drm_source);
+	wl_list_for_each_safe(weston_seat, next, &ec->base.seat_list, link)
+		evdev_input_destroy(weston_seat);
+err_sprite:
+	destroy_sprites(ec);
+err_egl:
+	eglMakeCurrent(ec->base.egl_display, EGL_NO_SURFACE, EGL_NO_SURFACE,
+		       EGL_NO_CONTEXT);
+	eglTerminate(ec->base.egl_display);
+	eglReleaseThread();
+	gbm_device_destroy(ec->gbm);
+err_udev_dev:
+	udev_device_unref(drm_device);
+err_udev_enum:
+	udev_enumerate_unref(e);
+	tty_destroy(ec->tty);
+err_udev:
+	udev_unref(ec->udev);
+err_compositor:
+	weston_compositor_shutdown(&ec->base);
+err_base:
+	free(ec);
+	return NULL;
 }
 
 WL_EXPORT struct weston_compositor *