text: Switch to weston_client_start instead of weston_client_launch

We really don't want to deal with sighups and pids.  It's far easier
to just deal with the client destroyed signal to respawn the input method.

Inspiration taken from Pekka's commit 826dc14ec4

This fixes a potential crash on shutdown.  If the input method client
pointer is still set (sighup handler hasn't run) but the client is
already destroyed, a call to text_backend_destroy() will try to destroy
the client a second time resulting in a segfault.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>

src/text-backend.c

@@ -100,13 +100,13 @@ struct text_backend {
 
 	struct {
 		char *path;
-		struct weston_process process;
 		struct wl_client *client;
 
 		unsigned deathcount;
 		uint32_t deathstamp;
 	} input_method;
 
+	struct wl_listener client_listener;
 	struct wl_listener seat_created_listener;
 };
 
@@ -922,14 +922,9 @@ input_method_init_seat(struct weston_seat *seat)
 static void launch_input_method(struct text_backend *text_backend);
 
 static void
-handle_input_method_sigchld(struct weston_process *process, int status)
+respawn_input_method_process(struct text_backend *text_backend)
 {
 	uint32_t time;
-	struct text_backend *text_backend =
-		container_of(process, struct text_backend, input_method.process);
-
-	text_backend->input_method.process.pid = 0;
-	text_backend->input_method.client = NULL;
 
 	/* if input_method dies more than 5 times in 10 seconds, give up */
 	time = weston_compositor_get_time();
@@ -940,14 +935,26 @@ handle_input_method_sigchld(struct weston_process *process, int status)
 
 	text_backend->input_method.deathcount++;
 	if (text_backend->input_method.deathcount > 5) {
-		weston_log("input_method died, giving up.\n");
+		weston_log("input_method disconnected, giving up.\n");
 		return;
 	}
 
-	weston_log("input_method died, respawning...\n");
+	weston_log("input_method disconnected, respawning...\n");
 	launch_input_method(text_backend);
 }
 
+static void
+input_method_client_notifier(struct wl_listener *listener, void *data)
+{
+	struct text_backend *text_backend;
+
+	text_backend = container_of(listener, struct text_backend,
+				    client_listener);
+
+	text_backend->input_method.client = NULL;
+	respawn_input_method_process(text_backend);
+}
+
 static void
 launch_input_method(struct text_backend *text_backend)
 {
@@ -957,18 +964,19 @@ launch_input_method(struct text_backend *text_backend)
 	if (strcmp(text_backend->input_method.path, "") == 0)
 		return;
 
-	if (text_backend->input_method.process.pid != 0)
-		return;
-
 	text_backend->input_method.client =
-		weston_client_launch(text_backend->compositor,
-				     &text_backend->input_method.process,
-				     text_backend->input_method.path,
-				     handle_input_method_sigchld);
+		weston_client_start(text_backend->compositor,
+				    text_backend->input_method.path);
 
-	if (!text_backend->input_method.client)
+	if (!text_backend->input_method.client) {
 		weston_log("not able to start %s\n",
 			   text_backend->input_method.path);
+		return;
+	}
+
+	text_backend->client_listener.notify = input_method_client_notifier;
+	wl_client_add_destroy_listener(text_backend->input_method.client,
+				       &text_backend->client_listener);
 }
 
 static void
@@ -1031,8 +1039,11 @@ text_backend_configuration(struct text_backend *text_backend)
 WL_EXPORT void
 text_backend_destroy(struct text_backend *text_backend)
 {
-	if (text_backend->input_method.client)
+	if (text_backend->input_method.client) {
+		/* disable respawn */
+		wl_list_remove(&text_backend->client_listener.link);
 		wl_client_destroy(text_backend->input_method.client);
+	}
 
 	free(text_backend->input_method.path);
 	free(text_backend);