protocol: add ei_connection.invalid_object

This event is to notify the client that an object used in a request was
unknown. This allows the client to work around race conditions like
binding to a seat that was removed.

This is currently the server-side only which is probably enough for now.
The only client-side created objects we have are the callbacks.

proto/protocol.xml

@@ -337,6 +337,17 @@
       <arg name="seat" type="new_id" interface="ei_seat"/>
       <arg name="version" type="uint" summary="the interface version"/>
     </event>
+
+    <event name="invalid_object" since="1">
+      <description summary="Invalid object in request notification">
+        Notification that an object ID used in a prior request was
+        invalid and does not exist.
+
+        This event is sent by the EIS implementation when an object that
+        does not exist as seen by the EIS implementation.
+      </description>
+      <arg name="invalid_id" type="uint" />
+    </event>
   </interface>
 
   <interface name="ei_callback" version="1">

src/brei-shared.c

@@ -291,6 +291,10 @@ brei_dispatch(struct brei_context *brei,
 		/* Find the object, it is stored in the ei/eis context  */
 		struct brei_object *object = NULL;
 		rc = lookup_object(object_id, &object, user_data);
+		if (rc == -ENOENT) {
+			iobuf_pop(buf, msglen);
+			continue;
+		}
 		if (rc < 0)
 			goto error;
 

src/libei.c

@@ -647,7 +647,8 @@ ei_connected(struct ei *ei)
 	}
 }
 
-static int handle_msg_disconnected(struct ei_connection *connection, uint32_t reason, const char *explanation)
+static int
+handle_msg_disconnected(struct ei_connection *connection, uint32_t reason, const char *explanation)
 {
 	struct ei *ei = ei_connection_get_context(connection);
 
@@ -659,6 +660,16 @@ static int handle_msg_disconnected(struct ei_connection *connection, uint32_t re
 	return -ECANCELED;
 }
 
+static int
+handle_msg_invalid_object(struct ei_connection *connection, uint32_t object)
+{
+	struct ei *ei = ei_connection_get_context(connection);
+
+	log_bug(ei, "Invalid object %#x, I don't yet know how to handle that", object);
+
+	return 0;
+}
+
 #define DISCONNECT_IF_SENDER_CONTEXT(ei_) do {\
 	if (ei_->is_sender) { \
 		log_bug_client(ei_, "Invalid event from receiver EIS context. Disconnecting"); \
@@ -669,6 +680,7 @@ static int handle_msg_disconnected(struct ei_connection *connection, uint32_t re
 static const struct ei_connection_interface interface = {
 	.disconnected = handle_msg_disconnected,
 	.seat = handle_msg_seat,
+	.invalid_object = handle_msg_invalid_object,
 };
 
 const struct ei_connection_interface *

src/libeis-client.c

@@ -321,6 +321,8 @@ lookup_object(uint32_t object_id, struct brei_object **object, void *userdata)
 	}
 
 	log_debug(eis_client_get_context(client), "Failed to find object %#x", object_id);
+	if (client->connection)
+		eis_connection_event_invalid_object(client->connection, object_id);
 
 	return -ENOENT;
 }