Allow session lock if existing session lock is no longer valid

This makes it possible to handle a crash in the session lock client by
restarting it, for instance. This is similar to how Sway behaves.

src/state.rs

@@ -50,6 +50,7 @@ use smithay::{
     output::{Mode as OutputMode, Output, Scale},
     reexports::{
         calloop::{LoopHandle, LoopSignal},
+        wayland_protocols::ext::session_lock::v1::server::ext_session_lock_v1::ExtSessionLockV1,
         wayland_protocols_misc::server_decoration::server::org_kde_kwin_server_decoration_manager::Mode,
         wayland_server::{
             backend::{ClientData, ClientId, DisconnectReason},
@@ -189,6 +190,7 @@ pub struct SurfaceDmabufFeedback {
 
 #[derive(Debug)]
 pub struct SessionLock {
+    pub ext_session_lock: ExtSessionLockV1,
     pub surfaces: HashMap<Output, LockSurface>,
 }
 

src/wayland/handlers/session_lock.rs

@@ -7,7 +7,7 @@ use crate::{
 use smithay::{
     delegate_session_lock,
     output::Output,
-    reexports::wayland_server::protocol::wl_output::WlOutput,
+    reexports::wayland_server::{protocol::wl_output::WlOutput, Resource},
     utils::Size,
     wayland::session_lock::{
         LockSurface, SessionLockHandler, SessionLockManagerState, SessionLocker,
@@ -21,12 +21,24 @@ impl SessionLockHandler for State {
     }
 
     fn lock(&mut self, locker: SessionLocker) {
-        if self.common.session_lock.is_none() {
-            locker.lock();
-            self.common.session_lock = Some(SessionLock {
-                surfaces: HashMap::new(),
-            });
+        // Reject lock if sesion lock exists and is still valid
+        if let Some(session_lock) = self.common.session_lock.as_ref() {
+            if self
+                .common
+                .display_handle
+                .get_client(session_lock.ext_session_lock.id())
+                .is_ok()
+            {
+                return;
+            }
         }
+
+        let ext_session_lock = locker.ext_session_lock().clone();
+        locker.lock();
+        self.common.session_lock = Some(SessionLock {
+            ext_session_lock,
+            surfaces: HashMap::new(),
+        });
     }
 
     fn unlock(&mut self) {