xwayland: refactor selection code

include/xwayland/selection.h

@@ -0,0 +1,72 @@
+#ifndef XWAYLAND_SELECTION_H
+#define XWAYLAND_SELECTION_H
+
+#include <xcb/xfixes.h>
+
+#define INCR_CHUNK_SIZE (64 * 1024)
+
+#define XDND_VERSION 5
+
+struct wlr_xwm_selection;
+
+struct wlr_xwm_selection_transfer {
+	struct wlr_xwm_selection *selection;
+
+	bool incr;
+	bool flush_property_on_delete;
+	bool property_set;
+	struct wl_array source_data;
+	int source_fd;
+	struct wl_event_source *source;
+
+	// when sending to x11
+	xcb_selection_request_event_t request;
+	struct wl_list outgoing_link;
+
+	// when receiving from x11
+	int property_start;
+	xcb_get_property_reply_t *property_reply;
+};
+
+struct wlr_xwm_selection {
+	struct wlr_xwm *xwm;
+	xcb_atom_t atom;
+	xcb_window_t window;
+	xcb_window_t owner;
+	xcb_timestamp_t timestamp;
+
+	struct wlr_xwm_selection_transfer incoming;
+	struct wl_list outgoing;
+};
+
+void xwm_selection_transfer_remove_source(
+	struct wlr_xwm_selection_transfer *transfer);
+void xwm_selection_transfer_close_source_fd(
+	struct wlr_xwm_selection_transfer *transfer);
+void xwm_selection_transfer_destroy_property_reply(
+	struct wlr_xwm_selection_transfer *transfer);
+
+xcb_atom_t xwm_mime_type_to_atom(struct wlr_xwm *xwm, char *mime_type);
+char *xwm_mime_type_from_atom(struct wlr_xwm *xwm, xcb_atom_t atom);
+struct wlr_xwm_selection *xwm_get_selection(struct wlr_xwm *xwm,
+	xcb_atom_t selection_atom);
+
+void xwm_send_incr_chunk(struct wlr_xwm_selection_transfer *transfer);
+void xwm_handle_selection_request(struct wlr_xwm *xwm,
+	xcb_selection_request_event_t *req);
+
+void xwm_get_incr_chunk(struct wlr_xwm_selection_transfer *transfer);
+void xwm_handle_selection_notify(struct wlr_xwm *xwm,
+	xcb_selection_notify_event_t *event);
+int xwm_handle_xfixes_selection_notify(struct wlr_xwm *xwm,
+	xcb_xfixes_selection_notify_event_t *event);
+bool wlr_data_source_is_xwayland_data_source(struct wlr_data_source *wlr_source);
+bool wlr_primary_selection_source_is_xwayland_primary_selection_source(
+	struct wlr_primary_selection_source *wlr_source);
+
+void xwm_seat_handle_start_drag(struct wlr_xwm *xwm, struct wlr_drag *drag);
+
+void xwm_selection_init(struct wlr_xwm *xwm);
+void xwm_selection_finish(struct wlr_xwm *xwm);
+
+#endif

include/xwayland/xwm.h

@@ -5,13 +5,18 @@
 #include <wlr/config.h>
 #include <wlr/xwayland.h>
 #include <xcb/render.h>
-
 #ifdef WLR_HAS_XCB_ICCCM
-	#include <xcb/xcb_icccm.h>
+#include <xcb/xcb_icccm.h>
 #endif
 #ifdef WLR_HAS_XCB_ERRORS
-	#include <xcb/xcb_errors.h>
+#include <xcb/xcb_errors.h>
 #endif
+#include "xwayland/selection.h"
+
+/* This is in xcb/xcb_event.h, but pulling xcb-util just for a constant
+ * others redefine anyway is meh
+ */
+#define XCB_EVENT_RESPONSE_TYPE_MASK (0x7f)
 
 enum atom_name {
 	WL_SURFACE_ID,
@@ -79,40 +84,6 @@ enum net_wm_state_action {
 	NET_WM_STATE_TOGGLE = 2,
 };
 
-#define XDND_VERSION 5
-
-struct wlr_xwm_selection;
-
-struct wlr_xwm_selection_transfer {
-	struct wlr_xwm_selection *selection;
-
-	bool incr;
-	bool flush_property_on_delete;
-	bool property_set;
-	struct wl_array source_data;
-	int source_fd;
-	struct wl_event_source *source;
-
-	// when sending to x11
-	xcb_selection_request_event_t request;
-	struct wl_list outgoing_link;
-
-	// when receiving from x11
-	int property_start;
-	xcb_get_property_reply_t *property_reply;
-};
-
-struct wlr_xwm_selection {
-	struct wlr_xwm *xwm;
-	xcb_atom_t atom;
-	xcb_window_t window;
-	xcb_window_t owner;
-	xcb_timestamp_t timestamp;
-
-	struct wlr_xwm_selection_transfer incoming;
-	struct wl_list outgoing;
-};
-
 struct wlr_xwm {
 	struct wlr_xwayland *xwayland;
 	struct wl_event_source *event_source;
@@ -168,15 +139,12 @@ void xwm_set_cursor(struct wlr_xwm *xwm, const uint8_t *pixels, uint32_t stride,
 
 int xwm_handle_selection_event(struct wlr_xwm *xwm, xcb_generic_event_t *event);
 int xwm_handle_selection_client_message(struct wlr_xwm *xwm,
-		xcb_client_message_event_t *ev);
-
-void xwm_selection_init(struct wlr_xwm *xwm);
-void xwm_selection_finish(struct wlr_xwm *xwm);
+	xcb_client_message_event_t *ev);
 
 void xwm_set_seat(struct wlr_xwm *xwm, struct wlr_seat *seat);
 
 char *xwm_get_atom_name(struct wlr_xwm *xwm, xcb_atom_t atom);
 bool xwm_atoms_contains(struct wlr_xwm *xwm, xcb_atom_t *atoms,
-		size_t num_atoms, enum atom_name needle);
+	size_t num_atoms, enum atom_name needle);
 
 #endif

xwayland/meson.build

@@ -1,7 +1,10 @@
 lib_wlr_xwayland = static_library(
 	'wlr_xwayland',
 	files(
-		'selection.c',
+		'selection/dnd.c',
+		'selection/incoming.c',
+		'selection/outgoing.c',
+		'selection/selection.c',
 		'sockets.c',
 		'xwayland.c',
 		'xwm.c',

xwayland/selection/dnd.c

@@ -0,0 +1,340 @@
+#define _XOPEN_SOURCE 700
+#include <assert.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <wlr/types/wlr_data_device.h>
+#include <wlr/types/wlr_primary_selection.h>
+#include <wlr/util/log.h>
+#include <xcb/xfixes.h>
+#include "xwayland/xwm.h"
+#include "xwayland/selection.h"
+
+static xcb_atom_t data_device_manager_dnd_action_to_atom(
+		struct wlr_xwm *xwm, enum wl_data_device_manager_dnd_action action) {
+	if (action & WL_DATA_DEVICE_MANAGER_DND_ACTION_COPY) {
+		return xwm->atoms[DND_ACTION_COPY];
+	} else if (action & WL_DATA_DEVICE_MANAGER_DND_ACTION_MOVE) {
+		return xwm->atoms[DND_ACTION_MOVE];
+	} else if (action & WL_DATA_DEVICE_MANAGER_DND_ACTION_ASK) {
+		return xwm->atoms[DND_ACTION_ASK];
+	}
+	return XCB_ATOM_NONE;
+}
+
+static enum wl_data_device_manager_dnd_action
+		data_device_manager_dnd_action_from_atom(struct wlr_xwm *xwm,
+		enum atom_name atom) {
+	if (atom == xwm->atoms[DND_ACTION_COPY] ||
+			atom == xwm->atoms[DND_ACTION_PRIVATE]) {
+		return WL_DATA_DEVICE_MANAGER_DND_ACTION_COPY;
+	} else if (atom == xwm->atoms[DND_ACTION_MOVE]) {
+		return WL_DATA_DEVICE_MANAGER_DND_ACTION_MOVE;
+	} else if (atom == xwm->atoms[DND_ACTION_ASK]) {
+		return WL_DATA_DEVICE_MANAGER_DND_ACTION_ASK;
+	}
+	return WL_DATA_DEVICE_MANAGER_DND_ACTION_NONE;
+}
+
+static void xwm_dnd_send_event(struct wlr_xwm *xwm, xcb_atom_t type,
+		xcb_client_message_data_t *data) {
+	struct wlr_xwayland_surface *dest = xwm->drag_focus;
+	assert(dest != NULL);
+
+	xcb_client_message_event_t event = {
+		.response_type = XCB_CLIENT_MESSAGE,
+		.format = 32,
+		.sequence = 0,
+		.window = dest->window_id,
+		.type = type,
+		.data = *data,
+	};
+
+	xcb_send_event(xwm->xcb_conn,
+		0, // propagate
+		dest->window_id,
+		XCB_EVENT_MASK_NO_EVENT,
+		(const char *)&event);
+	xcb_flush(xwm->xcb_conn);
+}
+
+static void xwm_dnd_send_enter(struct wlr_xwm *xwm) {
+	struct wlr_drag *drag = xwm->drag;
+	assert(drag != NULL);
+	struct wl_array *mime_types = &drag->source->mime_types;
+
+	xcb_client_message_data_t data = { 0 };
+	data.data32[0] = xwm->dnd_window;
+	data.data32[1] = XDND_VERSION << 24;
+
+	// If we have 3 MIME types or less, we can send them directly in the
+	// DND_ENTER message
+	size_t n = mime_types->size / sizeof(char *);
+	if (n <= 3) {
+		size_t i = 0;
+		char **mime_type_ptr;
+		wl_array_for_each(mime_type_ptr, mime_types) {
+			char *mime_type = *mime_type_ptr;
+			data.data32[2+i] = xwm_mime_type_to_atom(xwm, mime_type);
+			++i;
+		}
+	} else {
+		// Let the client know that targets are not contained in the message
+		// data and must be retrieved with the DND_TYPE_LIST property
+		data.data32[1] |= 1;
+
+		xcb_atom_t targets[n];
+		size_t i = 0;
+		char **mime_type_ptr;
+		wl_array_for_each(mime_type_ptr, mime_types) {
+			char *mime_type = *mime_type_ptr;
+			targets[i] = xwm_mime_type_to_atom(xwm, mime_type);
+			++i;
+		}
+
+		xcb_change_property(xwm->xcb_conn,
+			XCB_PROP_MODE_REPLACE,
+			xwm->dnd_window,
+			xwm->atoms[DND_TYPE_LIST],
+			XCB_ATOM_ATOM,
+			32, // format
+			n, targets);
+	}
+
+	xwm_dnd_send_event(xwm, xwm->atoms[DND_ENTER], &data);
+}
+
+static void xwm_dnd_send_position(struct wlr_xwm *xwm, uint32_t time, int16_t x,
+		int16_t y) {
+	struct wlr_drag *drag = xwm->drag;
+	assert(drag != NULL);
+
+	xcb_client_message_data_t data = { 0 };
+	data.data32[0] = xwm->dnd_window;
+	data.data32[2] = (x << 16) | y;
+	data.data32[3] = time;
+	data.data32[4] =
+		data_device_manager_dnd_action_to_atom(xwm, drag->source->actions);
+
+	xwm_dnd_send_event(xwm, xwm->atoms[DND_POSITION], &data);
+}
+
+static void xwm_dnd_send_drop(struct wlr_xwm *xwm, uint32_t time) {
+	struct wlr_drag *drag = xwm->drag;
+	assert(drag != NULL);
+	struct wlr_xwayland_surface *dest = xwm->drag_focus;
+	assert(dest != NULL);
+
+	xcb_client_message_data_t data = { 0 };
+	data.data32[0] = xwm->dnd_window;
+	data.data32[2] = time;
+
+	xwm_dnd_send_event(xwm, xwm->atoms[DND_DROP], &data);
+}
+
+static void xwm_dnd_send_leave(struct wlr_xwm *xwm) {
+	struct wlr_drag *drag = xwm->drag;
+	assert(drag != NULL);
+	struct wlr_xwayland_surface *dest = xwm->drag_focus;
+	assert(dest != NULL);
+
+	xcb_client_message_data_t data = { 0 };
+	data.data32[0] = xwm->dnd_window;
+
+	xwm_dnd_send_event(xwm, xwm->atoms[DND_LEAVE], &data);
+}
+
+/*static void xwm_dnd_send_finished(struct wlr_xwm *xwm) {
+	struct wlr_drag *drag = xwm->drag;
+	assert(drag != NULL);
+	struct wlr_xwayland_surface *dest = xwm->drag_focus;
+	assert(dest != NULL);
+
+	xcb_client_message_data_t data = { 0 };
+	data.data32[0] = xwm->dnd_window;
+	data.data32[1] = drag->source->accepted;
+
+	if (drag->source->accepted) {
+		data.data32[2] = data_device_manager_dnd_action_to_atom(xwm,
+			drag->source->current_dnd_action);
+	}
+
+	xwm_dnd_send_event(xwm, xwm->atoms[DND_FINISHED], &data);
+}*/
+
+int xwm_handle_selection_client_message(struct wlr_xwm *xwm,
+		xcb_client_message_event_t *ev) {
+	if (ev->type == xwm->atoms[DND_STATUS]) {
+		if (xwm->drag == NULL) {
+			wlr_log(L_DEBUG, "ignoring XdndStatus client message because "
+				"there's no drag");
+			return 1;
+		}
+
+		xcb_client_message_data_t *data = &ev->data;
+		xcb_window_t target_window = data->data32[0];
+		bool accepted = data->data32[1] & 1;
+		xcb_atom_t action_atom = data->data32[4];
+
+		if (xwm->drag_focus == NULL ||
+				target_window != xwm->drag_focus->window_id) {
+			wlr_log(L_DEBUG, "ignoring XdndStatus client message because "
+				"it doesn't match the current drag focus window ID");
+			return 1;
+		}
+
+		enum wl_data_device_manager_dnd_action action =
+			data_device_manager_dnd_action_from_atom(xwm, action_atom);
+
+		struct wlr_drag *drag = xwm->drag;
+		assert(drag != NULL);
+
+		drag->source->accepted = accepted;
+		wlr_data_source_dnd_action(drag->source, action);
+
+		wlr_log(L_DEBUG, "DND_STATUS window=%d accepted=%d action=%d",
+			target_window, accepted, action);
+		return 1;
+	} else if (ev->type == xwm->atoms[DND_FINISHED]) {
+		// This should only happen after the drag has ended, but before the drag
+		// source is destroyed
+		if (xwm->seat == NULL || xwm->seat->drag_source == NULL ||
+				xwm->drag != NULL) {
+			wlr_log(L_DEBUG, "ignoring XdndFinished client message because "
+				"there's no finished drag");
+			return 1;
+		}
+
+		struct wlr_data_source *source = xwm->seat->drag_source;
+
+		xcb_client_message_data_t *data = &ev->data;
+		xcb_window_t target_window = data->data32[0];
+		bool performed = data->data32[1] & 1;
+		xcb_atom_t action_atom = data->data32[2];
+
+		if (xwm->drag_focus == NULL ||
+				target_window != xwm->drag_focus->window_id) {
+			wlr_log(L_DEBUG, "ignoring XdndFinished client message because "
+				"it doesn't match the finished drag focus window ID");
+			return 1;
+		}
+
+		enum wl_data_device_manager_dnd_action action =
+			data_device_manager_dnd_action_from_atom(xwm, action_atom);
+
+		if (performed) {
+			wlr_data_source_dnd_finish(source);
+		}
+
+		wlr_log(L_DEBUG, "DND_FINISH window=%d performed=%d action=%d",
+			target_window, performed, action);
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+static void seat_handle_drag_focus(struct wl_listener *listener, void *data) {
+	struct wlr_drag *drag = data;
+	struct wlr_xwm *xwm = wl_container_of(listener, xwm, seat_drag_focus);
+
+	struct wlr_xwayland_surface *focus = NULL;
+	if (drag->focus != NULL) {
+		// TODO: check for subsurfaces?
+		struct wlr_xwayland_surface *surface;
+		wl_list_for_each(surface, &xwm->surfaces, link) {
+			if (surface->surface == drag->focus) {
+				focus = surface;
+				break;
+			}
+		}
+	}
+
+	if (focus == xwm->drag_focus) {
+		return;
+	}
+
+	if (xwm->drag_focus != NULL) {
+		wlr_data_source_dnd_action(drag->source,
+			WL_DATA_DEVICE_MANAGER_DND_ACTION_NONE);
+		xwm_dnd_send_leave(xwm);
+	}
+
+	xwm->drag_focus = focus;
+
+	if (xwm->drag_focus != NULL) {
+		xwm_dnd_send_enter(xwm);
+	}
+}
+
+static void seat_handle_drag_motion(struct wl_listener *listener, void *data) {
+	struct wlr_xwm *xwm = wl_container_of(listener, xwm, seat_drag_motion);
+	struct wlr_drag_motion_event *event = data;
+	struct wlr_xwayland_surface *surface = xwm->drag_focus;
+
+	if (surface == NULL) {
+		return; // No xwayland surface focused
+	}
+
+	xwm_dnd_send_position(xwm, event->time, surface->x + (int16_t)event->sx,
+		surface->y + (int16_t)event->sy);
+}
+
+static void seat_handle_drag_drop(struct wl_listener *listener, void *data) {
+	struct wlr_xwm *xwm = wl_container_of(listener, xwm, seat_drag_drop);
+	struct wlr_drag_drop_event *event = data;
+
+	if (xwm->drag_focus == NULL) {
+		return; // No xwayland surface focused
+	}
+
+	wlr_log(L_DEBUG, "Wayland drag dropped over an Xwayland window");
+	xwm_dnd_send_drop(xwm, event->time);
+}
+
+static void seat_handle_drag_destroy(struct wl_listener *listener, void *data) {
+	struct wlr_xwm *xwm = wl_container_of(listener, xwm, seat_drag_destroy);
+
+	// Don't reset drag focus yet because the target will read the drag source
+	// right after
+	if (xwm->drag_focus != NULL && !xwm->drag->source->accepted) {
+		wlr_log(L_DEBUG, "Wayland drag cancelled over an Xwayland window");
+		xwm_dnd_send_leave(xwm);
+	}
+
+	wl_list_remove(&xwm->seat_drag_focus.link);
+	wl_list_remove(&xwm->seat_drag_motion.link);
+	wl_list_remove(&xwm->seat_drag_drop.link);
+	wl_list_remove(&xwm->seat_drag_destroy.link);
+	xwm->drag = NULL;
+}
+
+static void seat_handle_drag_source_destroy(struct wl_listener *listener,
+		void *data) {
+	struct wlr_xwm *xwm =
+		wl_container_of(listener, xwm, seat_drag_source_destroy);
+
+	wl_list_remove(&xwm->seat_drag_source_destroy.link);
+	xwm->drag_focus = NULL;
+}
+
+void xwm_seat_handle_start_drag(struct wlr_xwm *xwm, struct wlr_drag *drag) {
+	xwm->drag = drag;
+	xwm->drag_focus = NULL;
+
+	if (drag != NULL) {
+		wl_signal_add(&drag->events.focus, &xwm->seat_drag_focus);
+		xwm->seat_drag_focus.notify = seat_handle_drag_focus;
+		wl_signal_add(&drag->events.motion, &xwm->seat_drag_motion);
+		xwm->seat_drag_motion.notify = seat_handle_drag_motion;
+		wl_signal_add(&drag->events.drop, &xwm->seat_drag_drop);
+		xwm->seat_drag_drop.notify = seat_handle_drag_drop;
+		wl_signal_add(&drag->events.destroy, &xwm->seat_drag_destroy);
+		xwm->seat_drag_destroy.notify = seat_handle_drag_destroy;
+
+		wl_signal_add(&drag->source->events.destroy,
+			&xwm->seat_drag_source_destroy);
+		xwm->seat_drag_source_destroy.notify = seat_handle_drag_source_destroy;
+	}
+}

xwayland/selection/incoming.c

@@ -0,0 +1,461 @@
+#define _XOPEN_SOURCE 700
+#include <assert.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <wlr/types/wlr_data_device.h>
+#include <wlr/types/wlr_primary_selection.h>
+#include <wlr/util/log.h>
+#include <xcb/xfixes.h>
+#include "xwayland/xwm.h"
+#include "xwayland/selection.h"
+
+/**
+ * Write the X11 selection to a Wayland client.
+ */
+static int xwm_data_source_write(int fd, uint32_t mask, void *data) {
+	struct wlr_xwm_selection_transfer *transfer = data;
+	struct wlr_xwm *xwm = transfer->selection->xwm;
+
+	char *property = xcb_get_property_value(transfer->property_reply);
+	int remainder = xcb_get_property_value_length(transfer->property_reply) -
+		transfer->property_start;
+
+	ssize_t len = write(fd, property + transfer->property_start, remainder);
+	if (len == -1) {
+		xwm_selection_transfer_destroy_property_reply(transfer);
+		xwm_selection_transfer_remove_source(transfer);
+		xwm_selection_transfer_close_source_fd(transfer);
+		wlr_log(L_ERROR, "write error to target fd: %m");
+		return 1;
+	}
+
+	wlr_log(L_DEBUG, "wrote %ld (chunk size %ld) of %d bytes",
+		transfer->property_start + len,
+		len, xcb_get_property_value_length(transfer->property_reply));
+
+	transfer->property_start += len;
+	if (len == remainder) {
+		xwm_selection_transfer_destroy_property_reply(transfer);
+		xwm_selection_transfer_remove_source(transfer);
+
+		if (transfer->incr) {
+			wlr_log(L_DEBUG, "deleting property");
+			xcb_delete_property(xwm->xcb_conn, transfer->selection->window,
+				xwm->atoms[WL_SELECTION]);
+			xcb_flush(xwm->xcb_conn);
+		} else {
+			wlr_log(L_DEBUG, "transfer complete");
+			xwm_selection_transfer_close_source_fd(transfer);
+		}
+	}
+
+	return 1;
+}
+
+static void xwm_write_property(struct wlr_xwm_selection_transfer *transfer,
+		xcb_get_property_reply_t *reply) {
+	struct wlr_xwm *xwm = transfer->selection->xwm;
+
+	transfer->property_start = 0;
+	transfer->property_reply = reply;
+
+	xwm_data_source_write(transfer->source_fd, WL_EVENT_WRITABLE, transfer);
+
+	if (transfer->property_reply != NULL) {
+		struct wl_event_loop *loop =
+			wl_display_get_event_loop(xwm->xwayland->wl_display);
+		transfer->source = wl_event_loop_add_fd(loop,
+			transfer->source_fd, WL_EVENT_WRITABLE, xwm_data_source_write,
+			transfer);
+	}
+}
+
+void xwm_get_incr_chunk(struct wlr_xwm_selection_transfer *transfer) {
+	struct wlr_xwm *xwm = transfer->selection->xwm;
+	wlr_log(L_DEBUG, "xwm_get_incr_chunk");
+
+	xcb_get_property_cookie_t cookie = xcb_get_property(xwm->xcb_conn,
+		0, // delete
+		transfer->selection->window,
+		xwm->atoms[WL_SELECTION],
+		XCB_GET_PROPERTY_TYPE_ANY,
+		0, // offset
+		0x1fffffff // length
+		);
+
+	xcb_get_property_reply_t *reply =
+		xcb_get_property_reply(xwm->xcb_conn, cookie, NULL);
+	if (reply == NULL) {
+		wlr_log(L_ERROR, "cannot get selection property");
+		return;
+	}
+	//dump_property(xwm, xwm->atoms[WL_SELECTION], reply);
+
+	if (xcb_get_property_value_length(reply) > 0) {
+		/* Reply's ownership is transferred to xwm, which is responsible
+		 * for freeing it */
+		xwm_write_property(transfer, reply);
+	} else {
+		wlr_log(L_DEBUG, "transfer complete");
+		xwm_selection_transfer_close_source_fd(transfer);
+		free(reply);
+	}
+}
+
+static void xwm_selection_get_data(struct wlr_xwm_selection *selection) {
+	struct wlr_xwm *xwm = selection->xwm;
+
+	xcb_get_property_cookie_t cookie = xcb_get_property(xwm->xcb_conn,
+		1, // delete
+		selection->window,
+		xwm->atoms[WL_SELECTION],
+		XCB_GET_PROPERTY_TYPE_ANY,
+		0, // offset
+		0x1fffffff // length
+		);
+
+	xcb_get_property_reply_t *reply =
+		xcb_get_property_reply(xwm->xcb_conn, cookie, NULL);
+	if (reply == NULL) {
+		wlr_log(L_ERROR, "Cannot get selection property");
+		return;
+	}
+
+	struct wlr_xwm_selection_transfer *transfer = &selection->incoming;
+	if (reply->type == xwm->atoms[INCR]) {
+		transfer->incr = true;
+		free(reply);
+	} else {
+		transfer->incr = false;
+		// reply's ownership is transferred to wm, which is responsible
+		// for freeing it
+		xwm_write_property(transfer, reply);
+	}
+}
+
+static void source_send(struct wlr_xwm_selection *selection,
+		struct wl_array *mime_types, struct wl_array *mime_types_atoms,
+		const char *requested_mime_type, int32_t fd) {
+	struct wlr_xwm *xwm = selection->xwm;
+	struct wlr_xwm_selection_transfer *transfer = &selection->incoming;
+
+	xcb_atom_t *atoms = mime_types_atoms->data;
+	bool found = false;
+	xcb_atom_t mime_type_atom;
+	char **mime_type_ptr;
+	size_t i = 0;
+	wl_array_for_each(mime_type_ptr, mime_types) {
+		char *mime_type = *mime_type_ptr;
+		if (strcmp(mime_type, requested_mime_type) == 0) {
+			found = true;
+			mime_type_atom = atoms[i];
+			break;
+		}
+		++i;
+	}
+	if (!found) {
+		wlr_log(L_DEBUG, "Cannot send X11 selection to Wayland: "
+			"unsupported MIME type");
+		return;
+	}
+
+	xcb_convert_selection(xwm->xcb_conn,
+		selection->window,
+		selection->atom,
+		mime_type_atom,
+		xwm->atoms[WL_SELECTION],
+		XCB_TIME_CURRENT_TIME);
+
+	xcb_flush(xwm->xcb_conn);
+
+	fcntl(fd, F_SETFL, O_WRONLY | O_NONBLOCK);
+	transfer->source_fd = fd;
+}
+
+struct x11_data_source {
+	struct wlr_data_source base;
+	struct wlr_xwm_selection *selection;
+	struct wl_array mime_types_atoms;
+};
+
+static const struct wlr_data_source_impl data_source_impl;
+
+bool wlr_data_source_is_xwayland_data_source(
+		struct wlr_data_source *wlr_source) {
+	return wlr_source->impl == &data_source_impl;
+}
+
+static struct x11_data_source *data_source_from_wlr_data_source(
+		struct wlr_data_source *wlr_source) {
+	assert(wlr_data_source_is_xwayland_data_source(wlr_source));
+	return (struct x11_data_source *)wlr_source;
+}
+
+static void data_source_send(struct wlr_data_source *wlr_source,
+		const char *mime_type, int32_t fd) {
+	struct x11_data_source *source =
+		data_source_from_wlr_data_source(wlr_source);
+	struct wlr_xwm_selection *selection = source->selection;
+
+	source_send(selection, &wlr_source->mime_types, &source->mime_types_atoms,
+		mime_type, fd);
+}
+
+static void data_source_cancel(struct wlr_data_source *wlr_source) {
+	struct x11_data_source *source =
+		data_source_from_wlr_data_source(wlr_source);
+	wlr_data_source_finish(&source->base);
+	wl_array_release(&source->mime_types_atoms);
+	free(source);
+}
+
+static const struct wlr_data_source_impl data_source_impl = {
+	.send = data_source_send,
+	.cancel = data_source_cancel,
+};
+
+struct x11_primary_selection_source {
+	struct wlr_primary_selection_source base;
+	struct wlr_xwm_selection *selection;
+	struct wl_array mime_types_atoms;
+};
+
+static void primary_selection_source_cancel(
+	struct wlr_primary_selection_source *wlr_source);
+
+bool wlr_primary_selection_source_is_xwayland_primary_selection_source(
+		struct wlr_primary_selection_source *wlr_source) {
+	return wlr_source->cancel == primary_selection_source_cancel;
+}
+
+static void primary_selection_source_send(
+		struct wlr_primary_selection_source *wlr_source, const char *mime_type,
+		int32_t fd) {
+	struct x11_primary_selection_source *source =
+		(struct x11_primary_selection_source *)wlr_source;
+	struct wlr_xwm_selection *selection = source->selection;
+
+	source_send(selection, &wlr_source->mime_types, &source->mime_types_atoms,
+		mime_type, fd);
+}
+
+static void primary_selection_source_cancel(
+		struct wlr_primary_selection_source *wlr_source) {
+	struct x11_primary_selection_source *source =
+		(struct x11_primary_selection_source *)wlr_source;
+	wlr_primary_selection_source_finish(&source->base);
+	wl_array_release(&source->mime_types_atoms);
+	free(source);
+}
+
+static bool source_get_targets(struct wlr_xwm_selection *selection,
+		struct wl_array *mime_types, struct wl_array *mime_types_atoms) {
+	struct wlr_xwm *xwm = selection->xwm;
+
+	xcb_get_property_cookie_t cookie = xcb_get_property(xwm->xcb_conn,
+		1, // delete
+		selection->window,
+		xwm->atoms[WL_SELECTION],
+		XCB_GET_PROPERTY_TYPE_ANY,
+		0, // offset
+		4096 // length
+		);
+
+	xcb_get_property_reply_t *reply =
+		xcb_get_property_reply(xwm->xcb_conn, cookie, NULL);
+	if (reply == NULL) {
+		return false;
+	}
+
+	if (reply->type != XCB_ATOM_ATOM) {
+		free(reply);
+		return false;
+	}
+
+	xcb_atom_t *value = xcb_get_property_value(reply);
+	for (uint32_t i = 0; i < reply->value_len; i++) {
+		char *mime_type = NULL;
+
+		if (value[i] == xwm->atoms[UTF8_STRING]) {
+			mime_type = strdup("text/plain;charset=utf-8");
+		} else if (value[i] == xwm->atoms[TEXT]) {
+			mime_type = strdup("text/plain");
+		} else if (value[i] != xwm->atoms[TARGETS] &&
+				value[i] != xwm->atoms[TIMESTAMP]) {
+			xcb_get_atom_name_cookie_t name_cookie =
+				xcb_get_atom_name(xwm->xcb_conn, value[i]);
+			xcb_get_atom_name_reply_t *name_reply =
+				xcb_get_atom_name_reply(xwm->xcb_conn, name_cookie, NULL);
+			if (name_reply == NULL) {
+				continue;
+			}
+			size_t len = xcb_get_atom_name_name_length(name_reply);
+			char *name = xcb_get_atom_name_name(name_reply); // not a C string
+			if (memchr(name, '/', len) != NULL) {
+				mime_type = malloc((len + 1) * sizeof(char));
+				if (mime_type == NULL) {
+					free(name_reply);
+					continue;
+				}
+				memcpy(mime_type, name, len);
+				mime_type[len] = '\0';
+			}
+			free(name_reply);
+		}
+
+		if (mime_type != NULL) {
+			char **mime_type_ptr =
+				wl_array_add(mime_types, sizeof(*mime_type_ptr));
+			if (mime_type_ptr == NULL) {
+				break;
+			}
+			*mime_type_ptr = mime_type;
+
+			xcb_atom_t *atom_ptr =
+				wl_array_add(mime_types_atoms, sizeof(*atom_ptr));
+			if (atom_ptr == NULL) {
+				break;
+			}
+			*atom_ptr = value[i];
+		}
+	}
+
+	free(reply);
+	return true;
+}
+
+static void xwm_selection_get_targets(struct wlr_xwm_selection *selection) {
+	// set the wayland selection to the X11 selection
+	struct wlr_xwm *xwm = selection->xwm;
+
+	if (selection == &xwm->clipboard_selection) {
+		struct x11_data_source *source =
+			calloc(1, sizeof(struct x11_data_source));
+		if (source == NULL) {
+			return;
+		}
+		wlr_data_source_init(&source->base, &data_source_impl);
+
+		source->selection = selection;
+		wl_array_init(&source->mime_types_atoms);
+
+		bool ok = source_get_targets(selection, &source->base.mime_types,
+			&source->mime_types_atoms);
+		if (ok) {
+			wlr_seat_set_selection(xwm->seat, &source->base,
+				wl_display_next_serial(xwm->xwayland->wl_display));
+		} else {
+			wlr_data_source_cancel(&source->base);
+		}
+	} else if (selection == &xwm->primary_selection) {
+		struct x11_primary_selection_source *source =
+			calloc(1, sizeof(struct x11_primary_selection_source));
+		if (source == NULL) {
+			return;
+		}
+		wlr_primary_selection_source_init(&source->base);
+		source->base.send = primary_selection_source_send;
+		source->base.cancel = primary_selection_source_cancel;
+
+		source->selection = selection;
+		wl_array_init(&source->mime_types_atoms);
+
+		bool ok = source_get_targets(selection, &source->base.mime_types,
+			&source->mime_types_atoms);
+		if (ok) {
+			wlr_seat_set_primary_selection(xwm->seat, &source->base,
+				wl_display_next_serial(xwm->xwayland->wl_display));
+		} else {
+			source->base.cancel(&source->base);
+		}
+	} else if (selection == &xwm->dnd_selection) {
+		// TODO
+	}
+}
+
+void xwm_handle_selection_notify(struct wlr_xwm *xwm,
+		xcb_selection_notify_event_t *event) {
+	wlr_log(L_DEBUG, "XCB_SELECTION_NOTIFY (selection=%u, property=%u, target=%u)",
+		event->selection, event->property,
+		event->target);
+
+	struct wlr_xwm_selection *selection =
+		xwm_get_selection(xwm, event->selection);
+	if (selection == NULL) {
+		return;
+	}
+
+	if (event->property == XCB_ATOM_NONE) {
+		wlr_log(L_ERROR, "convert selection failed");
+	} else if (event->target == xwm->atoms[TARGETS]) {
+		// No xwayland surface focused, deny access to clipboard
+		if (xwm->focus_surface == NULL) {
+			wlr_log(L_DEBUG, "denying write access to clipboard: "
+				"no xwayland surface focused");
+			return;
+		}
+
+		// This sets the Wayland clipboard (by calling wlr_seat_set_selection)
+		xwm_selection_get_targets(selection);
+	} else {
+		xwm_selection_get_data(selection);
+	}
+}
+
+int xwm_handle_xfixes_selection_notify(struct wlr_xwm *xwm,
+		xcb_xfixes_selection_notify_event_t *event) {
+	wlr_log(L_DEBUG, "XCB_XFIXES_SELECTION_NOTIFY (selection=%u, owner=%u)",
+		event->selection, event->owner);
+
+	struct wlr_xwm_selection *selection =
+		xwm_get_selection(xwm, event->selection);
+	if (selection == NULL) {
+		return 0;
+	}
+
+	if (event->owner == XCB_WINDOW_NONE) {
+		if (selection->owner != selection->window) {
+			// A real X client selection went away, not our
+			// proxy selection
+			if (selection == &xwm->clipboard_selection) {
+				wlr_seat_set_selection(xwm->seat, NULL,
+					wl_display_next_serial(xwm->xwayland->wl_display));
+			} else if (selection == &xwm->primary_selection) {
+				wlr_seat_set_primary_selection(xwm->seat, NULL,
+					wl_display_next_serial(xwm->xwayland->wl_display));
+			} else if (selection == &xwm->dnd_selection) {
+				// TODO: DND
+			} else {
+				wlr_log(L_DEBUG, "X11 selection has been cleared, but cannot "
+					"clear Wayland selection");
+			}
+		}
+
+		selection->owner = XCB_WINDOW_NONE;
+		return 1;
+	}
+
+	selection->owner = event->owner;
+
+	// We have to use XCB_TIME_CURRENT_TIME when we claim the
+	// selection, so grab the actual timestamp here so we can
+	// answer TIMESTAMP conversion requests correctly.
+	if (event->owner == selection->window) {
+		selection->timestamp = event->timestamp;
+		return 1;
+	}
+
+	struct wlr_xwm_selection_transfer *transfer = &selection->incoming;
+	transfer->incr = false;
+	// doing this will give a selection notify where we actually handle the sync
+	xcb_convert_selection(xwm->xcb_conn, selection->window,
+		selection->atom,
+		xwm->atoms[TARGETS],
+		xwm->atoms[WL_SELECTION],
+		event->timestamp);
+	xcb_flush(xwm->xcb_conn);
+
+	return 1;
+}

xwayland/selection/outgoing.c

@@ -0,0 +1,420 @@
+#define _XOPEN_SOURCE 700
+#include <assert.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <wlr/types/wlr_data_device.h>
+#include <wlr/types/wlr_primary_selection.h>
+#include <wlr/util/log.h>
+#include <xcb/xfixes.h>
+#include "xwayland/xwm.h"
+#include "xwayland/selection.h"
+
+static void xwm_selection_send_notify(struct wlr_xwm *xwm,
+		xcb_selection_request_event_t *req, bool success) {
+	xcb_selection_notify_event_t selection_notify = {
+		.response_type = XCB_SELECTION_NOTIFY,
+		.sequence = 0,
+		.time = req->time,
+		.requestor = req->requestor,
+		.selection = req->selection,
+		.target = req->target,
+		.property = success ? req->property : XCB_ATOM_NONE,
+	};
+
+	wlr_log(L_DEBUG, "SendEvent destination=%d SelectionNotify(31) time=%d "
+		"requestor=%d selection=%d target=%d property=%d", req->requestor,
+		req->time, req->requestor, req->selection, req->target,
+		selection_notify.property);
+	xcb_send_event(xwm->xcb_conn,
+		0, // propagate
+		req->requestor,
+		XCB_EVENT_MASK_NO_EVENT,
+		(const char *)&selection_notify);
+	xcb_flush(xwm->xcb_conn);
+}
+
+static int xwm_selection_flush_source_data(
+		struct wlr_xwm_selection_transfer *transfer) {
+	xcb_change_property(transfer->selection->xwm->xcb_conn,
+		XCB_PROP_MODE_REPLACE,
+		transfer->request.requestor,
+		transfer->request.property,
+		transfer->request.target,
+		8, // format
+		transfer->source_data.size,
+		transfer->source_data.data);
+	xcb_flush(transfer->selection->xwm->xcb_conn);
+	transfer->property_set = true;
+	size_t length = transfer->source_data.size;
+	transfer->source_data.size = 0;
+	return length;
+}
+
+static void xwm_selection_transfer_start_outgoing(
+		struct wlr_xwm_selection_transfer *transfer);
+
+static void xwm_selection_transfer_destroy_outgoing(
+		struct wlr_xwm_selection_transfer *transfer) {
+	wl_list_remove(&transfer->outgoing_link);
+
+	// Start next queued transfer
+	struct wlr_xwm_selection_transfer *first = NULL;
+	if (!wl_list_empty(&transfer->selection->outgoing)) {
+		first = wl_container_of(transfer->selection->outgoing.prev, first,
+			outgoing_link);
+		xwm_selection_transfer_start_outgoing(first);
+	}
+
+	xwm_selection_transfer_remove_source(transfer);
+	xwm_selection_transfer_close_source_fd(transfer);
+	wl_array_release(&transfer->source_data);
+	free(transfer);
+}
+
+static int xwm_data_source_read(int fd, uint32_t mask, void *data) {
+	struct wlr_xwm_selection_transfer *transfer = data;
+	struct wlr_xwm *xwm = transfer->selection->xwm;
+
+	void *p;
+	size_t current = transfer->source_data.size;
+	if (transfer->source_data.size < INCR_CHUNK_SIZE) {
+		p = wl_array_add(&transfer->source_data, INCR_CHUNK_SIZE);
+		if (p == NULL) {
+			wlr_log(L_ERROR, "Could not allocate selection source_data");
+			goto error_out;
+		}
+	} else {
+		p = (char *)transfer->source_data.data + transfer->source_data.size;
+	}
+
+	size_t available = transfer->source_data.alloc - current;
+	ssize_t len = read(fd, p, available);
+	if (len == -1) {
+		wlr_log(L_ERROR, "read error from data source: %m");
+		goto error_out;
+	}
+
+	wlr_log(L_DEBUG, "read %ld bytes (available %zu, mask 0x%x)", len,
+		available, mask);
+
+	transfer->source_data.size = current + len;
+	if (transfer->source_data.size >= INCR_CHUNK_SIZE) {
+		if (!transfer->incr) {
+			wlr_log(L_DEBUG, "got %zu bytes, starting incr",
+				transfer->source_data.size);
+
+			size_t incr_chunk_size = INCR_CHUNK_SIZE;
+			xcb_change_property(xwm->xcb_conn,
+				XCB_PROP_MODE_REPLACE,
+				transfer->request.requestor,
+				transfer->request.property,
+				xwm->atoms[INCR],
+				32, /* format */
+				1, &incr_chunk_size);
+			transfer->incr = true;
+			transfer->property_set = true;
+			transfer->flush_property_on_delete = true;
+			xwm_selection_transfer_remove_source(transfer);
+			xwm_selection_send_notify(xwm, &transfer->request, true);
+		} else if (transfer->property_set) {
+			wlr_log(L_DEBUG, "got %zu bytes, waiting for property delete",
+				transfer->source_data.size);
+
+			transfer->flush_property_on_delete = true;
+			xwm_selection_transfer_remove_source(transfer);
+		} else {
+			wlr_log(L_DEBUG, "got %zu bytes, property deleted, setting new "
+				"property", transfer->source_data.size);
+			xwm_selection_flush_source_data(transfer);
+		}
+	} else if (len == 0 && !transfer->incr) {
+		wlr_log(L_DEBUG, "non-incr transfer complete");
+		xwm_selection_flush_source_data(transfer);
+		xwm_selection_send_notify(xwm, &transfer->request, true);
+		xwm_selection_transfer_destroy_outgoing(transfer);
+	} else if (len == 0 && transfer->incr) {
+		wlr_log(L_DEBUG, "incr transfer complete");
+
+		transfer->flush_property_on_delete = true;
+		if (transfer->property_set) {
+			wlr_log(L_DEBUG, "got %zu bytes, waiting for property delete",
+				transfer->source_data.size);
+		} else {
+			wlr_log(L_DEBUG, "got %zu bytes, property deleted, setting new "
+				"property", transfer->source_data.size);
+			xwm_selection_flush_source_data(transfer);
+		}
+		xwm_selection_transfer_remove_source(transfer);
+		xwm_selection_transfer_close_source_fd(transfer);
+	} else {
+		wlr_log(L_DEBUG, "nothing happened, buffered the bytes");
+	}
+
+	return 1;
+
+error_out:
+	xwm_selection_send_notify(xwm, &transfer->request, false);
+	xwm_selection_transfer_destroy_outgoing(transfer);
+	return 0;
+}
+
+void xwm_send_incr_chunk(struct wlr_xwm_selection_transfer *transfer) {
+	wlr_log(L_DEBUG, "property deleted");
+
+	transfer->property_set = false;
+	if (transfer->flush_property_on_delete) {
+		wlr_log(L_DEBUG, "setting new property, %zu bytes",
+			transfer->source_data.size);
+		transfer->flush_property_on_delete = false;
+		int length = xwm_selection_flush_source_data(transfer);
+
+		if (transfer->source_fd >= 0) {
+			xwm_selection_transfer_start_outgoing(transfer);
+		} else if (length > 0) {
+			/* Transfer is all done, but queue a flush for
+			 * the delete of the last chunk so we can set
+			 * the 0 sized property to signal the end of
+			 * the transfer. */
+			transfer->flush_property_on_delete = true;
+			wl_array_release(&transfer->source_data);
+			wl_array_init(&transfer->source_data);
+		} else {
+			xwm_selection_transfer_destroy_outgoing(transfer);
+		}
+	}
+}
+
+static void xwm_selection_source_send(struct wlr_xwm_selection *selection,
+		const char *mime_type, int32_t fd) {
+	if (selection == &selection->xwm->clipboard_selection) {
+		struct wlr_data_source *source =
+			selection->xwm->seat->selection_source;
+		if (source != NULL) {
+			wlr_data_source_send(source, mime_type, fd);
+			return;
+		}
+	} else if (selection == &selection->xwm->primary_selection) {
+		struct wlr_primary_selection_source *source =
+			selection->xwm->seat->primary_selection_source;
+		if (source != NULL) {
+			source->send(source, mime_type, fd);
+			return;
+		}
+	} else if (selection == &selection->xwm->dnd_selection) {
+		struct wlr_data_source *source =
+			selection->xwm->seat->drag_source;
+		if (source != NULL) {
+			wlr_data_source_send(source, mime_type, fd);
+			return;
+		}
+	}
+
+	wlr_log(L_DEBUG, "not sending selection: no selection source available");
+}
+
+static void xwm_selection_transfer_start_outgoing(
+		struct wlr_xwm_selection_transfer *transfer) {
+	struct wlr_xwm *xwm = transfer->selection->xwm;
+	struct wl_event_loop *loop =
+		wl_display_get_event_loop(xwm->xwayland->wl_display);
+	transfer->source = wl_event_loop_add_fd(loop, transfer->source_fd,
+		WL_EVENT_READABLE, xwm_data_source_read, transfer);
+}
+
+static struct wl_array *xwm_selection_source_get_mime_types(
+		struct wlr_xwm_selection *selection) {
+	if (selection == &selection->xwm->clipboard_selection) {
+		struct wlr_data_source *source =
+			selection->xwm->seat->selection_source;
+		if (source != NULL) {
+			return &source->mime_types;
+		}
+	} else if (selection == &selection->xwm->primary_selection) {
+		struct wlr_primary_selection_source *source =
+			selection->xwm->seat->primary_selection_source;
+		if (source != NULL) {
+			return &source->mime_types;
+		}
+	} else if (selection == &selection->xwm->dnd_selection) {
+		struct wlr_data_source *source =
+			selection->xwm->seat->drag_source;
+		if (source != NULL) {
+			return &source->mime_types;
+		}
+	}
+	return NULL;
+}
+
+/**
+ * Read the Wayland selection and send it to an Xwayland client.
+ */
+static void xwm_selection_send_data(struct wlr_xwm_selection *selection,
+		xcb_selection_request_event_t *req, const char *mime_type) {
+	// Check MIME type
+	struct wl_array *mime_types =
+		xwm_selection_source_get_mime_types(selection);
+	if (mime_types == NULL) {
+		wlr_log(L_ERROR, "not sending selection: no MIME type list available");
+		xwm_selection_send_notify(selection->xwm, req, false);
+		return;
+	}
+
+	bool found = false;
+	char **mime_type_ptr;
+	wl_array_for_each(mime_type_ptr, mime_types) {
+		char *t = *mime_type_ptr;
+		if (strcmp(t, mime_type) == 0) {
+			found = true;
+			break;
+		}
+	}
+	if (!found) {
+		wlr_log(L_ERROR, "not sending selection: "
+			"requested an unsupported MIME type %s", mime_type);
+		xwm_selection_send_notify(selection->xwm, req, false);
+		return;
+	}
+
+	struct wlr_xwm_selection_transfer *transfer =
+		calloc(1, sizeof(struct wlr_xwm_selection_transfer));
+	if (transfer == NULL) {
+		wlr_log(L_ERROR, "Allocation failed");
+		return;
+	}
+	transfer->selection = selection;
+	transfer->request = *req;
+	wl_array_init(&transfer->source_data);
+
+	int p[2];
+	if (pipe(p) == -1) {
+		wlr_log(L_ERROR, "pipe() failed: %m");
+		xwm_selection_send_notify(selection->xwm, req, false);
+		return;
+	}
+	fcntl(p[0], F_SETFD, FD_CLOEXEC);
+	fcntl(p[0], F_SETFL, O_NONBLOCK);
+	fcntl(p[1], F_SETFD, FD_CLOEXEC);
+	fcntl(p[1], F_SETFL, O_NONBLOCK);
+
+	transfer->source_fd = p[0];
+
+	wlr_log(L_DEBUG, "Sending Wayland selection %u to Xwayland window with "
+		"MIME type %s, target %u", req->target, mime_type, req->target);
+	xwm_selection_source_send(selection, mime_type, p[1]);
+
+	wl_list_insert(&selection->outgoing, &transfer->outgoing_link);
+
+	// We can only handle one transfer at a time
+	if (wl_list_length(&selection->outgoing) == 1) {
+		xwm_selection_transfer_start_outgoing(transfer);
+	}
+}
+
+static void xwm_selection_send_targets(struct wlr_xwm_selection *selection,
+		xcb_selection_request_event_t *req) {
+	struct wlr_xwm *xwm = selection->xwm;
+
+	struct wl_array *mime_types =
+		xwm_selection_source_get_mime_types(selection);
+	if (mime_types == NULL) {
+		wlr_log(L_ERROR, "not sending selection targets: "
+			"no selection source available");
+		xwm_selection_send_notify(selection->xwm, req, false);
+		return;
+	}
+
+	size_t n = 2 + mime_types->size / sizeof(char *);
+	xcb_atom_t targets[n];
+	targets[0] = xwm->atoms[TIMESTAMP];
+	targets[1] = xwm->atoms[TARGETS];
+
+	size_t i = 0;
+	char **mime_type_ptr;
+	wl_array_for_each(mime_type_ptr, mime_types) {
+		char *mime_type = *mime_type_ptr;
+		targets[2+i] = xwm_mime_type_to_atom(xwm, mime_type);
+		++i;
+	}
+
+	xcb_change_property(xwm->xcb_conn,
+		XCB_PROP_MODE_REPLACE,
+		req->requestor,
+		req->property,
+		XCB_ATOM_ATOM,
+		32, // format
+		n, targets);
+
+	xwm_selection_send_notify(selection->xwm, req, true);
+}
+
+static void xwm_selection_send_timestamp(struct wlr_xwm_selection *selection,
+		xcb_selection_request_event_t *req) {
+	xcb_change_property(selection->xwm->xcb_conn,
+		XCB_PROP_MODE_REPLACE,
+		req->requestor,
+		req->property,
+		XCB_ATOM_INTEGER,
+		32, // format
+		1, &selection->timestamp);
+
+	xwm_selection_send_notify(selection->xwm, req, true);
+}
+
+void xwm_handle_selection_request(struct wlr_xwm *xwm,
+		xcb_selection_request_event_t *req) {
+	wlr_log(L_DEBUG, "XCB_SELECTION_REQUEST (time=%u owner=%u, requestor=%u "
+		"selection=%u, target=%u, property=%u)",
+		req->time, req->owner, req->requestor, req->selection, req->target,
+		req->property);
+
+	if (req->selection == xwm->atoms[CLIPBOARD_MANAGER]) {
+		// The wlroots clipboard should already have grabbed the first target,
+		// so just send selection notify now. This isn't synchronized with the
+		// clipboard finishing getting the data, so there's a race here.
+		xwm_selection_send_notify(xwm, req, true);
+		return;
+	}
+
+	struct wlr_xwm_selection *selection =
+		xwm_get_selection(xwm, req->selection);
+	if (selection == NULL) {
+		wlr_log(L_DEBUG, "received selection request for unknown selection");
+		return;
+	}
+
+	if (selection->window != req->owner) {
+		wlr_log(L_DEBUG, "received selection request with invalid owner");
+		return;
+	}
+
+	// No xwayland surface focused, deny access to clipboard
+	if (xwm->focus_surface == NULL && xwm->drag_focus == NULL) {
+		char *selection_name = xwm_get_atom_name(xwm, selection->atom);
+		wlr_log(L_DEBUG, "denying read access to selection %u (%s): "
+			"no xwayland surface focused", selection->atom, selection_name);
+		free(selection_name);
+		xwm_selection_send_notify(xwm, req, false);
+		return;
+	}
+
+	if (req->target == xwm->atoms[TARGETS]) {
+		xwm_selection_send_targets(selection, req);
+	} else if (req->target == xwm->atoms[TIMESTAMP]) {
+		xwm_selection_send_timestamp(selection, req);
+	} else if (req->target == xwm->atoms[DELETE]) {
+		xwm_selection_send_notify(selection->xwm, req, true);
+	} else {
+		// Send data
+		char *mime_type = xwm_mime_type_from_atom(xwm, req->target);
+		if (mime_type == NULL) {
+			wlr_log(L_ERROR, "ignoring selection request: unknown atom %u",
+				req->target);
+			xwm_selection_send_notify(xwm, req, false);
+			return;
+		}
+		xwm_selection_send_data(selection, req, mime_type);
+		free(mime_type);
+	}
+}

xwayland/selection/selection.c

@@ -0,0 +1,319 @@
+#define _XOPEN_SOURCE 700
+#include <assert.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <wlr/types/wlr_data_device.h>
+#include <wlr/types/wlr_primary_selection.h>
+#include <wlr/util/log.h>
+#include <xcb/xfixes.h>
+#include "xwayland/xwm.h"
+#include "xwayland/selection.h"
+
+void xwm_selection_transfer_remove_source(
+		struct wlr_xwm_selection_transfer *transfer) {
+	if (transfer->source != NULL) {
+		wl_event_source_remove(transfer->source);
+		transfer->source = NULL;
+	}
+}
+
+void xwm_selection_transfer_close_source_fd(
+		struct wlr_xwm_selection_transfer *transfer) {
+	if (transfer->source_fd >= 0) {
+		close(transfer->source_fd);
+		transfer->source_fd = -1;
+	}
+}
+
+void xwm_selection_transfer_destroy_property_reply(
+		struct wlr_xwm_selection_transfer *transfer) {
+	free(transfer->property_reply);
+	transfer->property_reply = NULL;
+}
+
+xcb_atom_t xwm_mime_type_to_atom(struct wlr_xwm *xwm, char *mime_type) {
+	if (strcmp(mime_type, "text/plain;charset=utf-8") == 0) {
+		return xwm->atoms[UTF8_STRING];
+	} else if (strcmp(mime_type, "text/plain") == 0) {
+		return xwm->atoms[TEXT];
+	}
+
+	xcb_intern_atom_cookie_t cookie =
+		xcb_intern_atom(xwm->xcb_conn, 0, strlen(mime_type), mime_type);
+	xcb_intern_atom_reply_t *reply =
+		xcb_intern_atom_reply(xwm->xcb_conn, cookie, NULL);
+	if (reply == NULL) {
+		return XCB_ATOM_NONE;
+	}
+	xcb_atom_t atom = reply->atom;
+	free(reply);
+	return atom;
+}
+
+char *xwm_mime_type_from_atom(struct wlr_xwm *xwm, xcb_atom_t atom) {
+	if (atom == xwm->atoms[UTF8_STRING]) {
+		return strdup("text/plain;charset=utf-8");
+	} else if (atom == xwm->atoms[TEXT]) {
+		return strdup("text/plain");
+	} else {
+		return xwm_get_atom_name(xwm, atom);
+	}
+}
+
+struct wlr_xwm_selection *xwm_get_selection(struct wlr_xwm *xwm,
+		xcb_atom_t selection_atom) {
+	if (selection_atom == xwm->atoms[CLIPBOARD]) {
+		return &xwm->clipboard_selection;
+	} else if (selection_atom == xwm->atoms[PRIMARY]) {
+		return &xwm->primary_selection;
+	} else if (selection_atom == xwm->atoms[DND_SELECTION]) {
+		return &xwm->dnd_selection;
+	} else {
+		return NULL;
+	}
+}
+
+static int xwm_handle_selection_property_notify(struct wlr_xwm *xwm,
+		xcb_property_notify_event_t *event) {
+	struct wlr_xwm_selection *selections[] = {
+		&xwm->clipboard_selection,
+		&xwm->primary_selection,
+		&xwm->dnd_selection,
+	};
+
+	for (size_t i = 0; i < sizeof(selections)/sizeof(selections[0]); ++i) {
+		struct wlr_xwm_selection *selection = selections[i];
+
+		if (event->window == selection->window) {
+			if (event->state == XCB_PROPERTY_NEW_VALUE &&
+					event->atom == xwm->atoms[WL_SELECTION] &&
+					selection->incoming.incr) {
+				xwm_get_incr_chunk(&selection->incoming);
+			}
+			return 1;
+		}
+
+		struct wlr_xwm_selection_transfer *outgoing;
+		wl_list_for_each(outgoing, &selection->outgoing, outgoing_link) {
+			if (event->window == outgoing->request.requestor) {
+				if (event->state == XCB_PROPERTY_DELETE &&
+						event->atom == outgoing->request.property &&
+						outgoing->incr) {
+					xwm_send_incr_chunk(outgoing);
+				}
+				return 1;
+			}
+		}
+	}
+
+	return 0;
+}
+
+int xwm_handle_selection_event(struct wlr_xwm *xwm,
+		xcb_generic_event_t *event) {
+	if (xwm->seat == NULL) {
+		wlr_log(L_DEBUG, "not handling selection events: "
+			"no seat assigned to xwayland");
+		return 0;
+	}
+
+	switch (event->response_type & XCB_EVENT_RESPONSE_TYPE_MASK) {
+	case XCB_SELECTION_NOTIFY:
+		xwm_handle_selection_notify(xwm, (xcb_selection_notify_event_t *)event);
+		return 1;
+	case XCB_PROPERTY_NOTIFY:
+		return xwm_handle_selection_property_notify(xwm,
+			(xcb_property_notify_event_t *)event);
+	case XCB_SELECTION_REQUEST:
+		xwm_handle_selection_request(xwm,
+			(xcb_selection_request_event_t *)event);
+		return 1;
+	}
+
+	switch (event->response_type - xwm->xfixes->first_event) {
+	case XCB_XFIXES_SELECTION_NOTIFY:
+		// an X11 window has copied something to the clipboard
+		return xwm_handle_xfixes_selection_notify(xwm,
+			(xcb_xfixes_selection_notify_event_t *)event);
+	}
+
+	return 0;
+}
+
+static void selection_init(struct wlr_xwm *xwm,
+		struct wlr_xwm_selection *selection, xcb_atom_t atom) {
+	selection->xwm = xwm;
+	selection->atom = atom;
+	selection->window = xwm->selection_window;
+	selection->incoming.selection = selection;
+	wl_list_init(&selection->outgoing);
+
+	uint32_t mask =
+		XCB_XFIXES_SELECTION_EVENT_MASK_SET_SELECTION_OWNER |
+		XCB_XFIXES_SELECTION_EVENT_MASK_SELECTION_WINDOW_DESTROY |
+		XCB_XFIXES_SELECTION_EVENT_MASK_SELECTION_CLIENT_CLOSE;
+	xcb_xfixes_select_selection_input(xwm->xcb_conn, selection->window,
+		selection->atom, mask);
+}
+
+void xwm_selection_init(struct wlr_xwm *xwm) {
+	// Clipboard and primary selection
+	uint32_t selection_values[] = {
+		XCB_EVENT_MASK_SUBSTRUCTURE_NOTIFY | XCB_EVENT_MASK_PROPERTY_CHANGE
+	};
+	xwm->selection_window = xcb_generate_id(xwm->xcb_conn);
+	xcb_create_window(xwm->xcb_conn,
+		XCB_COPY_FROM_PARENT,
+		xwm->selection_window,
+		xwm->screen->root,
+		0, 0,
+		10, 10,
+		0,
+		XCB_WINDOW_CLASS_INPUT_OUTPUT,
+		xwm->screen->root_visual,
+		XCB_CW_EVENT_MASK, selection_values);
+
+	xcb_set_selection_owner(xwm->xcb_conn,
+		xwm->selection_window,
+		xwm->atoms[CLIPBOARD_MANAGER],
+		XCB_TIME_CURRENT_TIME);
+
+	selection_init(xwm, &xwm->clipboard_selection, xwm->atoms[CLIPBOARD]);
+	selection_init(xwm, &xwm->primary_selection, xwm->atoms[PRIMARY]);
+
+	// Drag'n'drop
+	uint32_t dnd_values[] = {
+		XCB_EVENT_MASK_SUBSTRUCTURE_NOTIFY | XCB_EVENT_MASK_PROPERTY_CHANGE
+	};
+	xwm->dnd_window = xcb_generate_id(xwm->xcb_conn);
+	xcb_create_window(xwm->xcb_conn,
+		XCB_COPY_FROM_PARENT,
+		xwm->dnd_window,
+		xwm->screen->root,
+		0, 0,
+		8192, 8192,
+		0,
+		XCB_WINDOW_CLASS_INPUT_ONLY,
+		xwm->screen->root_visual,
+		XCB_CW_EVENT_MASK, dnd_values);
+
+	uint32_t version = XDND_VERSION;
+	xcb_change_property(xwm->xcb_conn,
+		XCB_PROP_MODE_REPLACE,
+		xwm->dnd_window,
+		xwm->atoms[DND_AWARE],
+		XCB_ATOM_ATOM,
+		32, // format
+		1, &version);
+
+	selection_init(xwm, &xwm->dnd_selection, xwm->atoms[DND_SELECTION]);
+}
+
+void xwm_selection_finish(struct wlr_xwm *xwm) {
+	if (!xwm) {
+		return;
+	}
+	if (xwm->selection_window) {
+		xcb_destroy_window(xwm->xcb_conn, xwm->selection_window);
+	}
+	if (xwm->dnd_window) {
+		xcb_destroy_window(xwm->xcb_conn, xwm->dnd_window);
+	}
+	if (xwm->seat) {
+		if (xwm->seat->selection_source &&
+				wlr_data_source_is_xwayland_data_source(
+					xwm->seat->selection_source)) {
+			wlr_seat_set_selection(xwm->seat, NULL,
+				wl_display_next_serial(xwm->xwayland->wl_display));
+		}
+		if (xwm->seat->primary_selection_source &&
+				wlr_primary_selection_source_is_xwayland_primary_selection_source(
+					xwm->seat->primary_selection_source)) {
+			wlr_seat_set_primary_selection(xwm->seat, NULL,
+				wl_display_next_serial(xwm->xwayland->wl_display));
+		}
+		wlr_xwayland_set_seat(xwm->xwayland, NULL);
+	}
+}
+
+static void xwm_selection_set_owner(struct wlr_xwm_selection *selection,
+		bool set) {
+	if (set) {
+		xcb_set_selection_owner(selection->xwm->xcb_conn,
+			selection->window,
+			selection->atom,
+			XCB_TIME_CURRENT_TIME);
+	} else {
+		if (selection->owner == selection->window) {
+			xcb_set_selection_owner(selection->xwm->xcb_conn,
+				XCB_WINDOW_NONE,
+				selection->atom,
+				selection->timestamp);
+		}
+	}
+}
+
+static void seat_handle_selection(struct wl_listener *listener,
+		void *data) {
+	struct wlr_seat *seat = data;
+	struct wlr_xwm *xwm =
+		wl_container_of(listener, xwm, seat_selection);
+	struct wlr_data_source *source = seat->selection_source;
+
+	if (source != NULL && wlr_data_source_is_xwayland_data_source(source)) {
+		return;
+	}
+
+	xwm_selection_set_owner(&xwm->clipboard_selection, source != NULL);
+}
+
+static void seat_handle_primary_selection(struct wl_listener *listener,
+		void *data) {
+	struct wlr_seat *seat = data;
+	struct wlr_xwm *xwm =
+		wl_container_of(listener, xwm, seat_primary_selection);
+	struct wlr_primary_selection_source *source = seat->primary_selection_source;
+
+	if (source != NULL &&
+			wlr_primary_selection_source_is_xwayland_primary_selection_source(
+				source)) {
+		return;
+	}
+
+	xwm_selection_set_owner(&xwm->primary_selection, source != NULL);
+}
+
+static void seat_handle_start_drag(struct wl_listener *listener, void *data) {
+	struct wlr_xwm *xwm = wl_container_of(listener, xwm, seat_start_drag);
+	struct wlr_drag *drag = data;
+
+	xwm_selection_set_owner(&xwm->dnd_selection, drag != NULL);
+	xwm_seat_handle_start_drag(xwm, drag);
+}
+
+void xwm_set_seat(struct wlr_xwm *xwm, struct wlr_seat *seat) {
+	if (xwm->seat != NULL) {
+		wl_list_remove(&xwm->seat_selection.link);
+		wl_list_remove(&xwm->seat_primary_selection.link);
+		wl_list_remove(&xwm->seat_start_drag.link);
+		xwm->seat = NULL;
+	}
+
+	if (seat == NULL) {
+		return;
+	}
+
+	xwm->seat = seat;
+
+	wl_signal_add(&seat->events.selection, &xwm->seat_selection);
+	xwm->seat_selection.notify = seat_handle_selection;
+	wl_signal_add(&seat->events.primary_selection, &xwm->seat_primary_selection);
+	xwm->seat_primary_selection.notify = seat_handle_primary_selection;
+	wl_signal_add(&seat->events.start_drag, &xwm->seat_start_drag);
+	xwm->seat_start_drag.notify = seat_handle_start_drag;
+
+	seat_handle_selection(&xwm->seat_selection, seat);
+	seat_handle_primary_selection(&xwm->seat_primary_selection, seat);
+}

xwayland/xwm.c

@@ -1055,10 +1055,6 @@ static void xwm_handle_unhandled_event(struct wlr_xwm *xwm, xcb_generic_event_t
 #endif
 }
 
-/* This is in xcb/xcb_event.h, but pulling xcb-util just for a constant
- * others redefine anyway is meh
- */
-#define XCB_EVENT_RESPONSE_TYPE_MASK (0x7f)
 static int x11_event_handler(int fd, uint32_t mask, void *data) {
 	int count = 0;
 	xcb_generic_event_t *event;