sessionLock: send locked instead of denied when missing a lock frame for 5 seconds (#14271)

The protocol seems to allow this, because it explicitly mentions either
session lock surface or compositor blanking the output in this sentence:

> The locked event must not be sent until a new "locked" frame
  (either from a session lock surface or the compositor blanking the output)
  has been presented on all outputs and no security sensitive normal/unlocked
  content is possibly visible.

Since `locked_screen_delay` is capped to 5 seconds,
after the 5 seconds this timer is registered for, we assume that
all outputs are covered either by lockedead or by an actual lock frame.
Thus sending locked is ok.

2 files changed, 16 insertions, 21 deletions

diff --git a/src/managers/SessionLockManager.cpp b/src/managers/SessionLockManager.cpp
index 8890e2e0..6e45c923 100644
--- a/src/managers/SessionLockManager.cpp
+++ b/src/managers/SessionLockManager.cpp
@@ -105,8 +105,10 @@ void CSessionLockManager::onNewSessionLock(SP<CSessionLock> pLock) {
         return;
     }
 
-    m_sessionLock->sendDeniedTimer = makeShared<CEventLoopTimer>(
-        // Within this arbitrary amount of time, a session-lock client is expected to create and commit a lock surface for each output. If the client fails to do that, it will be denied.
+    m_sessionLock->sendLockedTimer = makeShared<CEventLoopTimer>(
+        // Clients get sent the "locked" event after they submitted a lock frame for each output.
+        // If they fail to do this, we send the "locked" event after a fixed amount of time here.
+        // Previously we sent denied after this timeout, but that forcefully makes the client exit and the protocol doesn't require that anyways.
         std::chrono::seconds(5),
         [](auto, auto) {
             if (!g_pSessionLockManager || g_pSessionLockManager->clientLocked() || g_pSessionLockManager->clientDenied())
@@ -115,29 +117,22 @@ void CSessionLockManager::onNewSessionLock(SP<CSessionLock> pLock) {
             if (!g_pSessionLockManager->m_sessionLock || !g_pSessionLockManager->m_sessionLock->lock)
                 return;
 
-            if (g_pCompositor->m_unsafeState || !g_pCompositor->m_aqBackend->hasSession() || !g_pCompositor->m_aqBackend->session->active) {
-                // Because the session is inactive, there is a good reason for why the client did't manage to render to all outputs.
-                // We send locked, although this could lead to imperfect frames when we start to render again.
-                g_pSessionLockManager->m_sessionLock->lock->sendLocked();
-                g_pSessionLockManager->m_sessionLock->hasSentLocked = true;
-                return;
-            }
-
-            LOGM(Log::WARN, "Kicking lockscreen client, because it failed to render to all outputs within 5 seconds");
-            g_pSessionLockManager->m_sessionLock->lock->sendDenied();
-            g_pSessionLockManager->m_sessionLock->hasSentDenied = true;
+            LOGM(Log::WARN,
+                 "Sending locked after a 5 second timeout. This happens when we failed to render a lock frame from the client for every output. Lockdead frames may be shown.");
+            g_pSessionLockManager->m_sessionLock->lock->sendLocked();
+            g_pSessionLockManager->m_sessionLock->hasSentLocked = true;
         },
         nullptr);
 
-    g_pEventLoopManager->addTimer(m_sessionLock->sendDeniedTimer);
+    g_pEventLoopManager->addTimer(m_sessionLock->sendLockedTimer);
 }
 
-void CSessionLockManager::removeSendDeniedTimer() {
-    if (!m_sessionLock || !m_sessionLock->sendDeniedTimer)
+void CSessionLockManager::removeSendLockedTimer() {
+    if (!m_sessionLock || !m_sessionLock->sendLockedTimer)
         return;
 
-    g_pEventLoopManager->removeTimer(m_sessionLock->sendDeniedTimer);
-    m_sessionLock->sendDeniedTimer.reset();
+    g_pEventLoopManager->removeTimer(m_sessionLock->sendLockedTimer);
+    m_sessionLock->sendLockedTimer.reset();
 }
 
 bool CSessionLockManager::isSessionLocked() {
@@ -169,7 +164,7 @@ void CSessionLockManager::onLockscreenRenderedOnMonitor(uint64_t id) {
         std::ranges::all_of(g_pCompositor->m_monitors, [this](auto m) { return !m->m_enabled || !m->m_dpmsStatus || m_sessionLock->lockedMonitors.contains(m->m_id); });
 
     if (LOCKED && m_sessionLock->lock->good()) {
-        removeSendDeniedTimer();
+        removeSendLockedTimer();
         m_sessionLock->lock->sendLocked();
         m_sessionLock->hasSentLocked = true;
     }
diff --git a/src/managers/SessionLockManager.hpp b/src/managers/SessionLockManager.hpp
index efcaf09a..dba2758e 100644
--- a/src/managers/SessionLockManager.hpp
+++ b/src/managers/SessionLockManager.hpp
@@ -31,7 +31,7 @@ struct SSessionLockSurface {
 struct SSessionLock {
     WP<CSessionLock>                     lock;
     CTimer                               lockTimer;
-    SP<CEventLoopTimer>                  sendDeniedTimer;
+    SP<CEventLoopTimer>                  sendLockedTimer;
 
     std::vector<SP<SSessionLockSurface>> vSessionLockSurfaces;
 
@@ -73,7 +73,7 @@ class CSessionLockManager {
     } m_listeners;
 
     void onNewSessionLock(SP<CSessionLock> pWlrLock);
-    void removeSendDeniedTimer();
+    void removeSendLockedTimer();
 };
 
 inline UP<CSessionLockManager> g_pSessionLockManager;