xwayland/selection: refactor remaining incremental transfer code

include/xwayland/selection.h

@@ -47,6 +47,7 @@ void xwm_selection_transfer_close_wl_client_fd(
 	struct wlr_xwm_selection_transfer *transfer);
 void xwm_selection_transfer_destroy_property_reply(
 	struct wlr_xwm_selection_transfer *transfer);
+void xwm_selection_transfer_finish(struct wlr_xwm_selection_transfer *transfer);
 bool xwm_selection_transfer_get_selection_property(
 	struct wlr_xwm_selection_transfer *transfer, bool delete);
 

xwayland/selection/incoming.c

@@ -15,16 +15,22 @@ static void xwm_notify_ready_for_next_incr_chunk(
 		struct wlr_xwm_selection_transfer *transfer) {
 	struct wlr_xwm *xwm = transfer->selection->xwm;
 	assert(transfer->incr);
+
 	wlr_log(WLR_DEBUG, "deleting property");
 	xcb_delete_property(xwm->xcb_conn, transfer->selection->window,
 		xwm->atoms[WL_SELECTION]);
 	xcb_flush(xwm->xcb_conn);
+
+	xwm_selection_transfer_remove_event_source(transfer);
+	xwm_selection_transfer_destroy_property_reply(transfer);
 }
 
 /**
- * Write the X11 selection to a Wayland client.
+ * Write the X11 selection to a Wayland client. Returns a nonzero value if the
+ * Wayland client might become writeable again in the future.
  */
-static int xwm_data_source_write(int fd, uint32_t mask, void *data) {
+static int write_selection_property_to_wl_client(int fd, uint32_t mask,
+		void *data) {
 	struct wlr_xwm_selection_transfer *transfer = data;
 
 	char *property = xcb_get_property_value(transfer->property_reply);
@@ -34,74 +40,68 @@ static int xwm_data_source_write(int fd, uint32_t mask, void *data) {
 	ssize_t len = write(fd, property + transfer->property_start, remainder);
 	if (len == -1) {
 		wlr_log_errno(WLR_ERROR, "write error to target fd %d", fd);
-		xwm_selection_transfer_destroy_property_reply(transfer);
-		xwm_selection_transfer_remove_event_source(transfer);
-		xwm_selection_transfer_close_wl_client_fd(transfer);
+		xwm_selection_transfer_finish(transfer);
 		return 0;
 	}
 
-	wlr_log(WLR_DEBUG, "wrote %zd (chunk size %zd) of %d bytes",
-		transfer->property_start + len,
-		len, xcb_get_property_value_length(transfer->property_reply));
+	wlr_log(WLR_DEBUG,
+		"wrote %zd (total %zd, remaining %d) of %d bytes to fd %d",
+		len, transfer->property_start + len, remainder,
+		xcb_get_property_value_length(transfer->property_reply), fd);
 
 	if (len < remainder) {
 		transfer->property_start += len;
-	} else {
-		xwm_selection_transfer_destroy_property_reply(transfer);
-		xwm_selection_transfer_remove_event_source(transfer);
-
-		if (transfer->incr) {
+		return 1;
+	} else if (transfer->incr) {
 		xwm_notify_ready_for_next_incr_chunk(transfer);
 	} else {
 		wlr_log(WLR_DEBUG, "transfer complete");
-			xwm_selection_transfer_close_wl_client_fd(transfer);
-		}
+		xwm_selection_transfer_finish(transfer);
 	}
 
-	return 1;
+	return 0;
 }
 
-static void xwm_write_property(struct wlr_xwm_selection_transfer *transfer) {
-	struct wlr_xwm *xwm = transfer->selection->xwm;
+static void xwm_write_selection_property_to_wl_client(
+		struct wlr_xwm_selection_transfer *transfer) {
+	if (transfer->incr && transfer->wl_client_fd < 0) {
+		// Wayland client closed its pipe prematurely before the X11 client finished
+		// its incremental transfer. Continue draining the X11 client.
+		xwm_notify_ready_for_next_incr_chunk(transfer);
+		return;
+	}
 
-	bool wl_client_finished_consuming =
-		!xwm_data_source_write(transfer->wl_client_fd, WL_EVENT_WRITABLE, transfer);
+	bool wl_client_finished_consuming = !write_selection_property_to_wl_client(
+			transfer->wl_client_fd, WL_EVENT_WRITABLE, transfer);
 	if (!wl_client_finished_consuming) {
 		// Wrote out part of the property to the Wayland client, but the client was
 		// unable to accept all of it. Schedule an event to asynchronously complete
 		// the transfer.
 		struct wl_event_loop *loop =
-			wl_display_get_event_loop(xwm->xwayland->wl_display);
+			wl_display_get_event_loop(transfer->selection->xwm->xwayland->wl_display);
 		transfer->event_source = wl_event_loop_add_fd(loop,
-			transfer->wl_client_fd, WL_EVENT_WRITABLE, xwm_data_source_write,
-			transfer);
+			transfer->wl_client_fd, WL_EVENT_WRITABLE,
+			write_selection_property_to_wl_client, transfer);
 	}
 }
 
 void xwm_get_incr_chunk(struct wlr_xwm_selection_transfer *transfer) {
 	wlr_log(WLR_DEBUG, "xwm_get_incr_chunk");
 
+	if (transfer->property_reply) {
+		wlr_log(WLR_ERROR, "X11 client offered a new property before we deleted");
+		return;
+	}
+
 	if (!xwm_selection_transfer_get_selection_property(transfer, false)) {
 		return;
 	}
 
 	if (xcb_get_property_value_length(transfer->property_reply) > 0) {
-		// Reply's ownership is transferred to xwm, which is responsible
-		// for freeing it.
-		if (transfer->wl_client_fd >= 0) {
-			// Wayland client is alive, property will be freed once it has finished
-			// reading it.
-			xwm_write_property(transfer);
-		} else {
-			// Wayland client closed its pipe prematurely (or died). Continue draining
-			// the X11 client.
-			xwm_notify_ready_for_next_incr_chunk(transfer);
-			xwm_selection_transfer_destroy_property_reply(transfer);
-		}
+		xwm_write_selection_property_to_wl_client(transfer);
 	} else {
+		xwm_selection_transfer_finish(transfer);
 		wlr_log(WLR_DEBUG, "incremental transfer complete");
-		xwm_selection_transfer_close_wl_client_fd(transfer);
-		xwm_selection_transfer_destroy_property_reply(transfer);
 	}
 }
 
@@ -118,9 +118,9 @@ static void xwm_selection_get_data(struct wlr_xwm_selection *selection) {
 		xwm_selection_transfer_destroy_property_reply(transfer);
 	} else {
 		transfer->incr = false;
-		// reply's ownership is transferred to wm, which is responsible
-		// for freeing it
-		xwm_write_property(transfer);
+		// Reply's ownership is transferred to wm, which is responsible for freeing
+		// it.
+		xwm_write_selection_property_to_wl_client(transfer);
 	}
 }
 

xwayland/selection/selection.c

@@ -33,6 +33,13 @@ void xwm_selection_transfer_destroy_property_reply(
 	transfer->property_reply = NULL;
 }
 
+void xwm_selection_transfer_finish(
+		struct wlr_xwm_selection_transfer *transfer) {
+	xwm_selection_transfer_destroy_property_reply(transfer);
+	xwm_selection_transfer_remove_event_source(transfer);
+	xwm_selection_transfer_close_wl_client_fd(transfer);
+}
+
 bool xwm_selection_transfer_get_selection_property(
 		struct wlr_xwm_selection_transfer *transfer, bool delete) {
 	struct wlr_xwm *xwm = transfer->selection->xwm;