xwayland: kill xwayland when wayland connection fails

src/client.rs

@@ -19,6 +19,7 @@ use {
             numcell::NumCell,
             pending_serial::PendingSerial,
             pid_info::{PidInfo, get_pid_info, get_socket_creds},
+            pidfd_send_signal::pidfd_send_signal,
         },
         wire::WlRegistryId,
     },
@@ -251,6 +252,13 @@ impl Drop for ClientHolder {
         self.data.surfaces_by_xwayland_serial.clear();
         self.data.remove_activation_tokens();
         self.data.commit_timelines.clear();
+        if self.data.is_xwayland {
+            if let Some(pidfd) = self.data.state.xwayland.pidfd.get() {
+                if let Err(e) = pidfd_send_signal(&pidfd, c::SIGKILL) {
+                    log::error!("Could not kill Xwayland: {}", ErrorFmt(e));
+                }
+            }
+        }
     }
 }
 

src/compositor.rs

@@ -218,6 +218,7 @@ fn start_compositor2(
         run_args,
         xwayland: XWaylandState {
             enabled: Cell::new(true),
+            pidfd: Default::default(),
             handler: Default::default(),
             queue: Default::default(),
             ipc_device_ids: Default::default(),

src/state.rs

@@ -121,6 +121,7 @@ use {
         time::Duration,
     },
     thiserror::Error,
+    uapi::OwnedFd,
 };
 
 pub struct State {
@@ -261,6 +262,7 @@ pub struct ScreenlockState {
 
 pub struct XWaylandState {
     pub enabled: Cell<bool>,
+    pub pidfd: CloneCell<Option<Rc<OwnedFd>>>,
     pub handler: RefCell<Option<SpawnedFuture<()>>>,
     pub queue: Rc<AsyncQueue<XWaylandEvent>>,
     pub ipc_device_ids: XIpcDeviceIds,

src/utils.rs

@@ -43,6 +43,7 @@ pub mod oserror;
 pub mod page_size;
 pub mod pending_serial;
 pub mod pid_info;
+pub mod pidfd_send_signal;
 pub mod process_name;
 pub mod ptr_ext;
 pub mod queue;

src/utils/pidfd_send_signal.rs

@@ -0,0 +1,23 @@
+use {
+    crate::utils::oserror::OsError,
+    c::{c_int, syscall},
+    std::{ptr, rc::Rc},
+    uapi::{
+        OwnedFd,
+        c::{self, SYS_pidfd_send_signal, siginfo_t},
+        map_err,
+    },
+};
+
+pub fn pidfd_send_signal(pidfd: &Rc<OwnedFd>, signal: c_int) -> Result<(), OsError> {
+    let res = unsafe {
+        syscall(
+            SYS_pidfd_send_signal,
+            pidfd.raw(),
+            signal,
+            ptr::null_mut::<siginfo_t>(),
+            0,
+        )
+    };
+    map_err!(res).map(drop).map_err(|e| e.into())
+}

src/xwayland.rs

@@ -14,7 +14,9 @@ use {
         io_uring::IoUringError,
         state::State,
         user_session::import_environment,
-        utils::{buf::Buf, errorfmt::ErrorFmt, line_logger::log_lines, oserror::OsError},
+        utils::{
+            buf::Buf, errorfmt::ErrorFmt, line_logger::log_lines, on_drop::OnDrop, oserror::OsError,
+        },
         wire::WlSurfaceId,
         xcon::XconError,
         xwayland::{
@@ -185,6 +187,10 @@ async fn run(
     state.update_xwayland_wire_scale();
     state.ring.readable(&Rc::new(dfdread)).await?;
     state.xwayland.queue.clear();
+    state.xwayland.pidfd.set(Some(pidfd.clone()));
+    let _remove_pidfd = OnDrop(|| {
+        state.xwayland.pidfd.take();
+    });
     {
         let shared = Rc::new(XwmShared::default());
         let wm = match Wm::get(state, client, wm1, &shared).await {