Add SIGTERM handling logic that properly shuts down the EE.

Author: adityamandaleeka

src/pal/inc/pal.h

@@ -6490,6 +6490,7 @@ struct PAL_SEHException
 
 typedef VOID (PALAPI *PHARDWARE_EXCEPTION_HANDLER)(PAL_SEHException* ex);
 typedef BOOL (PALAPI *PHARDWARE_EXCEPTION_SAFETY_CHECK_FUNCTION)(PCONTEXT contextRecord, PEXCEPTION_RECORD exceptionRecord);
+typedef VOID (PALAPI *PTERMINATION_REQUEST_HANDLER)();
 typedef DWORD (PALAPI *PGET_GCMARKER_EXCEPTION_CODE)(LPVOID ip);
 
 PALIMPORT
@@ -6512,6 +6513,12 @@ PAL_ThrowExceptionFromContext(
     IN CONTEXT* context,
     IN PAL_SEHException* ex);
 
+PALIMPORT
+VOID
+PALAPI
+PAL_SetTerminationRequestHandler(
+    IN PTERMINATION_REQUEST_HANDLER terminationRequestHandler);
+
 //
 // This holder is used to indicate that a hardware
 // exception should be raised as a C++ exception

src/pal/src/exception/signal.cpp

@@ -72,6 +72,7 @@ static void sigtrap_handler(int code, siginfo_t *siginfo, void *context);
 static void sigbus_handler(int code, siginfo_t *siginfo, void *context);
 static void sigint_handler(int code, siginfo_t *siginfo, void *context);
 static void sigquit_handler(int code, siginfo_t *siginfo, void *context);
+static void sigterm_handler(int code, siginfo_t *siginfo, void *context);
 
 static void common_signal_handler(int code, siginfo_t *siginfo, void *sigcontext, int numParams, ...);
 
@@ -91,7 +92,7 @@ struct sigaction g_previous_sigbus;
 struct sigaction g_previous_sigsegv;
 struct sigaction g_previous_sigint;
 struct sigaction g_previous_sigquit;
-
+struct sigaction g_previous_sigterm;
 
 /* public function definitions ************************************************/
 
@@ -131,6 +132,7 @@ BOOL SEHInitializeSignals()
     handle_signal(SIGSEGV, sigsegv_handler, &g_previous_sigsegv);
     handle_signal(SIGINT, sigint_handler, &g_previous_sigint);
     handle_signal(SIGQUIT, sigquit_handler, &g_previous_sigquit);
+    handle_signal(SIGTERM, sigterm_handler, &g_previous_sigterm);
 
 #ifdef INJECT_ACTIVATION_SIGNAL
     handle_signal(INJECT_ACTIVATION_SIGNAL, inject_activation_handler, NULL);
@@ -178,6 +180,7 @@ void SEHCleanupSignals()
     restore_signal(SIGSEGV, &g_previous_sigsegv);
     restore_signal(SIGINT, &g_previous_sigint);
     restore_signal(SIGQUIT, &g_previous_sigquit);
+    restore_signal(SIGTERM, &g_previous_sigterm);
 }
 
 /* internal function definitions **********************************************/
@@ -384,6 +387,35 @@ static void sigquit_handler(int code, siginfo_t *siginfo, void *context)
     kill(gPID, code);
 }
 
+/*++
+Function :
+    sigterm_handler
+
+    handle SIGTERM signal
+
+Parameters :
+    POSIX signal handler parameter list ("man sigaction" for details)
+
+    (no return value)
+--*/
+static void sigterm_handler(int code, siginfo_t *siginfo, void *context)
+{
+    if (PALIsInitialized())
+    {
+        // g_pSynchronizationManager shouldn't be null if PAL is initialized.
+        _ASSERTE(g_pSynchronizationManager != nullptr);
+
+        g_pSynchronizationManager->SendTerminationRequestToWorkerThread();
+    }
+    else
+    {
+        if (g_previous_sigterm.sa_sigaction != NULL)
+        {
+            g_previous_sigterm.sa_sigaction(code, siginfo, context);
+        }
+    }
+}
+
 #ifdef INJECT_ACTIVATION_SIGNAL
 /*++
 Function :

src/pal/src/include/pal/corunix.hpp

@@ -1124,6 +1124,10 @@ namespace CorUnix
             CPalThread *pThread
             ) = 0;
 
+        virtual
+        PAL_ERROR
+        SendTerminationRequestToWorkerThread() = 0;
+
         //
         // This routine is primarily meant for use by WaitForMultipleObjects[Ex].
         // The caller must individually release each of the returned controller