From bad03394e067eb6ca85523d5a66ac482c4147364 Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Fri, 28 Jul 2023 14:09:51 +0200
Subject: [PATCH] xwayland: introduce wlr_xwm_reply_handler

This is a helper to asynchronously wait for a reply from the X11
server.
---
 include/xwayland/xwm.h | 16 ++++++++++++++++
 xwayland/xwm.c         | 32 +++++++++++++++++++++++++++++++-
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/include/xwayland/xwm.h b/include/xwayland/xwm.h
index 7db5d6cb8..0701d8f66 100644
--- a/include/xwayland/xwm.h
+++ b/include/xwayland/xwm.h
@@ -91,6 +91,17 @@ enum atom_name {
 	ATOM_LAST // keep last
 };
 
+struct wlr_xwm_reply_handler;
+
+typedef void (*xwm_reply_handler_func_t)(struct wlr_xwm *xwm,
+	struct wlr_xwm_reply_handler *reply_handler, xcb_generic_reply_t *reply);
+
+struct wlr_xwm_reply_handler {
+	unsigned int request;
+	xwm_reply_handler_func_t callback;
+	struct wl_list link;
+};
+
 struct wlr_xwm {
 	struct wlr_xwayland *xwayland;
 	struct wl_event_source *event_source;
@@ -106,6 +117,8 @@ struct wlr_xwm {
 	xcb_render_pictformat_t render_format_id;
 	xcb_cursor_t cursor;
 
+	struct wl_list reply_handlers; // wlr_xwm_reply_handler.link
+
 	struct wlr_xwm_selection clipboard_selection;
 	struct wlr_xwm_selection primary_selection;
 	struct wlr_xwm_selection dnd_selection;
@@ -160,4 +173,7 @@ 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);
 
+void xwm_init_reply_handler(struct wlr_xwm *xwm, struct wlr_xwm_reply_handler *handler,
+	unsigned int request, xwm_reply_handler_func_t callback);
+
 #endif
diff --git a/xwayland/xwm.c b/xwayland/xwm.c
index 6597af9ad..405eb32a9 100644
--- a/xwayland/xwm.c
+++ b/xwayland/xwm.c
@@ -16,6 +16,7 @@
 #include <xcb/composite.h>
 #include <xcb/render.h>
 #include <xcb/res.h>
+#include <xcb/xcbext.h>
 #include <xcb/xfixes.h>
 #include "xwayland/xwm.h"
 
@@ -1644,7 +1645,6 @@ static void xwm_handle_unhandled_event(struct wlr_xwm *xwm, xcb_generic_event_t
 
 static int x11_event_handler(int fd, uint32_t mask, void *data) {
 	int count = 0;
-	xcb_generic_event_t *event;
 	struct wlr_xwm *xwm = data;
 
 	if ((mask & WL_EVENT_HANGUP) || (mask & WL_EVENT_ERROR)) {
@@ -1652,6 +1652,18 @@ static int x11_event_handler(int fd, uint32_t mask, void *data) {
 		return 0;
 	}
 
+	struct wlr_xwm_reply_handler *reply_handler, *reply_handler_tmp;
+	wl_list_for_each_safe(reply_handler, reply_handler_tmp, &xwm->reply_handlers, link) {
+		void *reply = NULL;
+		if (!xcb_poll_for_reply(xwm->xcb_conn, reply_handler->request, &reply, NULL)) {
+			break;
+		}
+		wl_list_remove(&reply_handler->link);
+		reply_handler->callback(xwm, reply_handler, reply);
+		free(reply);
+	}
+
+	xcb_generic_event_t *event;
 	while ((event = xcb_poll_for_event(xwm->xcb_conn))) {
 		count++;
 
@@ -1716,6 +1728,18 @@ static int x11_event_handler(int fd, uint32_t mask, void *data) {
 	return count;
 }
 
+void xwm_init_reply_handler(struct wlr_xwm *xwm, struct wlr_xwm_reply_handler *handler,
+		uint32_t request, xwm_reply_handler_func_t callback) {
+	if (request == 0) {
+		// Failed to send the request
+		callback(xwm, handler, NULL);
+		return;
+	}
+	handler->request = request;
+	handler->callback = callback;
+	wl_list_insert(xwm->reply_handlers.prev, &handler->link);
+}
+
 static void handle_compositor_new_surface(struct wl_listener *listener,
 		void *data) {
 	struct wlr_xwm *xwm =
@@ -1887,6 +1911,11 @@ void xwm_destroy(struct wlr_xwm *xwm) {
 	wl_list_for_each_safe(xsurface, tmp, &xwm->unpaired_surfaces, unpaired_link) {
 		xwayland_surface_destroy(xsurface);
 	}
+	struct wlr_xwm_reply_handler *reply_handler, *reply_handler_tmp;
+	wl_list_for_each_safe(reply_handler, reply_handler_tmp, &xwm->reply_handlers, link) {
+		wl_list_remove(&reply_handler->link);
+		reply_handler->callback(xwm, reply_handler, NULL);
+	}
 	wl_list_remove(&xwm->compositor_new_surface.link);
 	wl_list_remove(&xwm->compositor_destroy.link);
 	wl_list_remove(&xwm->shell_v1_new_surface.link);
@@ -2139,6 +2168,7 @@ struct wlr_xwm *xwm_create(struct wlr_xwayland *xwayland, int wm_fd) {
 	wl_list_init(&xwm->surfaces_in_stack_order);
 	wl_list_init(&xwm->unpaired_surfaces);
 	wl_list_init(&xwm->pending_startup_ids);
+	wl_list_init(&xwm->reply_handlers);
 	xwm->ping_timeout = 10000;
 
 	xwm->xcb_conn = xcb_connect_to_fd(wm_fd, NULL);