Map between X11 Windows and WlSurfaces

Xwayland gives us a mapping between X11 window and WlSurface IDs via
special WL_SURFACE_ID messages. This commit uses these messages to find
the corresponding WlSurface. For this, the new client.get_resource API
from wayland-server is needed.

Signed-off-by: Uli Schlachter <psychon@znc.in>

Cargo.toml

@@ -31,7 +31,7 @@ udev = { version = "0.5", optional = true }
 wayland-commons = { version = "0.28", optional = true }
 wayland-egl = { version = "0.28", optional = true }
 wayland-protocols = { version = "0.28", features = ["unstable_protocols", "server"], optional = true }
-wayland-server = { version = "0.28", optional = true }
+wayland-server = { version = "0.28.3", optional = true }
 wayland-sys = { version = "0.28", optional = true }
 winit = { version = "0.23.0", optional = true }
 xkbcommon = "0.4.0"

anvil/src/shell.rs

@@ -768,6 +768,9 @@ fn surface_commit(
     buffer_utils: &BufferUtils,
     window_map: &RefCell<MyWindowMap>,
 ) {
+    #[cfg(feature = "xwayland")]
+    super::xwayland::commit_hook(surface);
+
     let mut geometry = None;
     let mut min_size = (0, 0);
     let mut max_size = (0, 0);

anvil/src/xwayland/mod.rs

@@ -1,9 +1,9 @@
-use std::{convert::TryFrom, os::unix::net::UnixStream, rc::Rc};
+use std::{cell::RefCell, collections::HashMap, convert::TryFrom, os::unix::net::UnixStream, rc::Rc};
 
 use smithay::{
     reexports::{
         calloop::LoopHandle,
-        wayland_server::Client,
+        wayland_server::{protocol::wl_surface::WlSurface, Client},
     },
     xwayland::XWindowManager,
 };
@@ -15,7 +15,7 @@ use x11rb::{
         composite::{ConnectionExt as _, Redirect},
         xproto::{
             ChangeWindowAttributesAux, ConfigWindow, ConfigureWindowAux, ConnectionExt as _, EventMask,
-            WindowClass,
+            Window, WindowClass,
         },
         Event,
     },
@@ -42,12 +42,15 @@ impl XWm {
 }
 
 impl XWindowManager for XWm {
-    fn xwayland_ready(&mut self, connection: UnixStream, _client: Client) {
+    fn xwayland_ready(&mut self, connection: UnixStream, client: Client) {
-        let (mut wm, source) = X11State::start_wm(connection, self.log.clone()).unwrap();
+        let (wm, source) = X11State::start_wm(connection, self.log.clone()).unwrap();
+        let wm = Rc::new(RefCell::new(wm));
+        client.data_map().insert_if_missing(|| Rc::clone(&wm));
         self.handle
             .insert_source(source, move |events, _, _| {
+                let mut wm = wm.borrow_mut();
                 for event in events.into_iter() {
-                    wm.handle_event(event)?;
+                    wm.handle_event(event, &client)?;
                 }
                 Ok(())
             })
@@ -69,6 +72,7 @@ struct X11State {
     conn: Rc<RustConnection>,
     atoms: Atoms,
     log: slog::Logger,
+    unpaired_surfaces: HashMap<u32, Window>,
 }
 
 impl X11State {
@@ -114,13 +118,14 @@ impl X11State {
         let wm = Self {
             conn: Rc::clone(&conn),
             atoms,
+            unpaired_surfaces: Default::default(),
             log,
         };
 
         Ok((wm, X11Source::new(conn)))
     }
 
-    fn handle_event(&mut self, event: Event) -> Result<(), ReplyOrIdError> {
+    fn handle_event(&mut self, event: Event, client: &Client) -> Result<(), ReplyOrIdError> {
         debug!(self.log, "X11: Got event {:?}", event);
         match event {
             Event::ConfigureRequest(r) => {
@@ -155,15 +160,47 @@ impl X11State {
             }
             Event::ClientMessage(msg) => {
                 if msg.type_ == self.atoms.WL_SURFACE_ID {
+                    // We get a WL_SURFACE_ID message when Xwayland creates a WlSurface for a
+                    // window. Both the creation of the surface and this client message happen at
+                    // roughly the same time and are sent over different sockets (X11 socket and
+                    // wayland socket). Thus, we could receive these two in any order. Hence, it
+                    // can happen that we get None below when X11 was faster than Wayland.
+
                     let id = msg.data.as_data32()[0];
+                    let surface = client.get_resource::<WlSurface>(id);
                     info!(
                         self.log,
-                        "X11 surface {:x?} corresponds to WlSurface {:x}", msg.window, id,
+                        "X11 surface {:x?} corresponds to WlSurface {:x} = {:?}", msg.window, id, surface,
                     );
+                    match surface {
+                        None => {
+                            self.unpaired_surfaces.insert(id, msg.window);
+                        }
+                        Some(surface) => self.new_window(msg.window, surface),
+                    }
                 }
             }
             _ => {}
         }
         Ok(())
     }
+
+    fn new_window(&mut self, window: Window, surface: WlSurface) {
+        debug!(self.log, "Matched X11 surface {:x?} to {:x?}", window, surface);
+    }
+}
+
+// Called when a WlSurface commits.
+pub fn commit_hook(surface: &WlSurface) {
+    // Is this the Xwayland client?
+    if let Some(client) = surface.as_ref().client() {
+        if let Some(x11) = client.data_map().get::<Rc<RefCell<X11State>>>() {
+            let mut inner = x11.borrow_mut();
+            // Is the surface among the unpaired surfaces (see comment next to WL_SURFACE_ID
+            // handling above)
+            if let Some(window) = inner.unpaired_surfaces.remove(&surface.as_ref().id()) {
+                inner.new_window(window, surface.clone());
+            }
+        }
+    }
 }