watchdog: add flag to mark handler as disabled

Adds flags that marks WinCtrlCHandlerRoutine as disabled instead of
removing it. Trying to remove the controller from the controller
handle itself leads to deadlock.

PR-URL: https://github.com/nodejs/node/pull/10248
Reviewed-By: Anna Henningsen <anna@addaleax.net>

src/node_watchdog.cc

@@ -150,7 +150,8 @@ void SigintWatchdogHelper::HandleSignal(int signum) {
 // Windows starts a separate thread for executing the handler, so no extra
 // helper thread is required.
 BOOL WINAPI SigintWatchdogHelper::WinCtrlCHandlerRoutine(DWORD dwCtrlType) {
-  if (dwCtrlType == CTRL_C_EVENT || dwCtrlType == CTRL_BREAK_EVENT) {
+  if (!instance.watchdog_disabled_ &&
+      (dwCtrlType == CTRL_C_EVENT || dwCtrlType == CTRL_BREAK_EVENT)) {
     InformWatchdogsAboutSignal();
 
     // Return true because the signal has been handled.
@@ -207,7 +208,11 @@ int SigintWatchdogHelper::Start() {
 
   RegisterSignalHandler(SIGINT, HandleSignal);
 #else
-  SetConsoleCtrlHandler(WinCtrlCHandlerRoutine, TRUE);
+  if (watchdog_disabled_) {
+    watchdog_disabled_ = false;
+  } else {
+    SetConsoleCtrlHandler(WinCtrlCHandlerRoutine, TRUE);
+  }
 #endif
 
   return 0;
@@ -251,7 +256,7 @@ bool SigintWatchdogHelper::Stop() {
 
   RegisterSignalHandler(SIGINT, SignalExit, true);
 #else
-  SetConsoleCtrlHandler(WinCtrlCHandlerRoutine, FALSE);
+  watchdog_disabled_ = true;
 #endif
 
   had_pending_signal = has_pending_signal_;
@@ -292,6 +297,8 @@ SigintWatchdogHelper::SigintWatchdogHelper()
   has_running_thread_ = false;
   stopping_ = false;
   CHECK_EQ(0, uv_sem_init(&sem_, 0));
+#else
+  watchdog_disabled_ = false;
 #endif
 }
 

src/node_watchdog.h

@@ -91,6 +91,7 @@ class SigintWatchdogHelper {
   static void* RunSigintWatchdog(void* arg);
   static void HandleSignal(int signum);
 #else
+  bool watchdog_disabled_;
   static BOOL WINAPI WinCtrlCHandlerRoutine(DWORD dwCtrlType);
 #endif
 };