Provide fix for #81093 - "Mono does not emit ProcessExit event on SIG…

…TERM" (#100056)

* src/mono/mono/mini/mini-posix.c
  - Add signal handler for SIGTERM

* src/mono/mono/mini/mini-windows.c
  - Add signal handler for SIGTERM
  - Use the correct signal for handler

* src/mono/mono/mini/mini-runtime.c
  - Add mono_sigterm_signal_handler to process SIGTERM that will set a global variable
    to be monitored by the GC finalizer thread
  - Set a default exit code before setting the term_signaled variable that gets checked in gc

* src/mono/mono/mini/mini-runtime.h
  - Define prototype for mono_sigterm_signal_handler()

* src/mono/mono/metadata/gc.c
  - Monitor for sigterm and kick off the shutdown process when encountered by calling mono_runtime_try_shutdown().
  - Exit with either the user set exitcode (System.Environment.ExitCode) or SIGTERM + 128.
  - Simplify use of exit code now that a default is being set
  - Rename term_signaled to match mono style
  - Remove volatile attribute
  - Move testing of shutdown until after the sem wait

* src/libraries/System.Runtime/tests/System/ExitCodeTests.Unix.cs
  - Re-enable ExitCodeTests for mono

* src/mono/mono/mini/exceptions-amd64.c
  src/mono/mono/mini/exceptions-x86.c
  - Add control event handling for windows

Co-authored-by: Jo Shields <directhex@apebox.org>

src/libraries/System.Runtime/tests/System.Runtime.Tests/System/ExitCodeTests.Unix.cs

@@ -16,7 +16,6 @@ public class ExitCodeTests
         private static extern int kill(int pid, int sig);
 
         [ConditionalTheory(typeof(RemoteExecutor), nameof(RemoteExecutor.IsSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/31656", TestRuntimes.Mono)]
         [InlineData(null)]
         [InlineData(0)]
         [InlineData(42)]

src/mono/mono/metadata/gc.c

@@ -24,6 +24,7 @@
 #include <mono/metadata/class-internals.h>
 #include <mono/metadata/metadata-internals.h>
 #include <mono/metadata/threads-types.h>
+#include <mono/metadata/runtime.h>
 #include <mono/sgen/sgen-conf.h>
 #include <mono/sgen/sgen-gc.h>
 #include <mono/utils/mono-logger-internals.h>
@@ -63,6 +64,8 @@ static gboolean gc_disabled;
 
 static gboolean finalizing_root_domain;
 
+extern gboolean mono_term_signaled;
+
 gboolean mono_log_finalizers;
 gboolean mono_do_not_finalize;
 static volatile gboolean suspend_finalizers;
@@ -852,6 +855,7 @@ finalizer_thread (gpointer unused)
 	mono_hazard_pointer_install_free_queue_size_callback (hazard_free_queue_is_too_big);
 
 	while (!finished) {
+
 		/* Wait to be notified that there's at least one
 		 * finaliser to run
 		 */
@@ -865,6 +869,12 @@ finalizer_thread (gpointer unused)
 		}
 		wait = TRUE;
 
+		/* Just in case we've received a SIGTERM */
+		if (mono_term_signaled) {
+			mono_runtime_try_shutdown();
+			exit(mono_environment_exitcode_get());
+		}
+
 		mono_thread_info_set_flags (MONO_THREAD_INFO_FLAGS_NONE);
 
 		/* The Finalizer thread doesn't initialize during creation because base managed

src/mono/mono/mini/exceptions-amd64.c

@@ -45,10 +45,14 @@
 #include "mono/utils/mono-tls-inline.h"
 
 #ifdef TARGET_WIN32
+#include <windows.h>
 static void (*restore_stack) (void);
 static MonoW32ExceptionHandler fpe_handler;
 static MonoW32ExceptionHandler ill_handler;
 static MonoW32ExceptionHandler segv_handler;
+static MonoW32ExceptionHandler term_handler = NULL;
+
+extern gboolean mono_term_signaled;
 
 LPTOP_LEVEL_EXCEPTION_FILTER mono_old_win_toplevel_exception_filter;
 void *mono_win_vectored_exception_handle;
@@ -214,6 +218,31 @@ void win32_seh_cleanup(void)
 	g_assert (ret);
 }
 
+BOOL WINAPI mono_win_ctrl_handler(DWORD fdwCtrlType)
+{
+	switch (fdwCtrlType) {
+	case CTRL_C_EVENT:
+		if (term_handler != NULL)
+			term_handler(0, NULL, NULL);
+		return TRUE;
+		break;
+	case CTRL_CLOSE_EVENT:
+		return TRUE;
+		break;
+	case CTRL_BREAK_EVENT:
+		return FALSE;
+		break;
+	case CTRL_LOGOFF_EVENT:
+		return FALSE;
+		break;
+	case CTRL_SHUTDOWN_EVENT:
+		return FALSE;
+		break;
+	default:
+		return FALSE;
+	}
+}
+
 void win32_seh_set_handler(int type, MonoW32ExceptionHandler handler)
 {
 	switch (type) {
@@ -226,6 +255,11 @@ void win32_seh_set_handler(int type, MonoW32ExceptionHandler handler)
 	case SIGSEGV:
 		segv_handler = handler;
 		break;
+	case SIGTERM:
+		term_handler = handler;
+		if (!SetConsoleCtrlHandler(mono_win_ctrl_handler, TRUE))
+			fprintf(stderr,"Cannot set control handler\n");
+		break;
 	default:
 		break;
 	}

src/mono/mono/mini/exceptions-x86.c

@@ -47,6 +47,7 @@ static void (*restore_stack) (void *);
 static MonoW32ExceptionHandler fpe_handler;
 static MonoW32ExceptionHandler ill_handler;
 static MonoW32ExceptionHandler segv_handler;
+static MonoW32ExceptionHandler term_handler = NULL;
 
 LPTOP_LEVEL_EXCEPTION_FILTER mono_old_win_toplevel_exception_filter;
 gpointer mono_win_vectored_exception_handle;
@@ -260,6 +261,31 @@ void win32_seh_cleanup(void)
 	RemoveVectoredExceptionHandler (mono_win_vectored_exception_handle);
 }
 
+BOOL WINAPI mono_win_ctrl_handler(DWORD fdwCtrlType)
+{
+	switch (fdwCtrlType) {
+	case CTRL_C_EVENT:
+		if (term_handler != NULL)
+			term_handler(0, NULL, NULL);
+		return TRUE;
+		break;
+	case CTRL_CLOSE_EVENT:
+		return TRUE;
+		break;
+	case CTRL_BREAK_EVENT:
+		return FALSE;
+		break;
+	case CTRL_LOGOFF_EVENT:
+		return FALSE;
+		break;
+	case CTRL_SHUTDOWN_EVENT:
+		return FALSE;
+		break;
+	default:
+		return FALSE;
+	}
+}
+
 void win32_seh_set_handler(int type, MonoW32ExceptionHandler handler)
 {
 	switch (type) {
@@ -272,6 +298,11 @@ void win32_seh_set_handler(int type, MonoW32ExceptionHandler handler)
 	case SIGSEGV:
 		segv_handler = handler;
 		break;
+	case SIGTERM:
+		term_handler = handler;
+		if (!SetConsoleCtrlHandler(mono_win_ctrl_handler, TRUE))
+			fprintf(stderr,"Cannot set control handler\n");
+		break;
 	default:
 		break;
 	}

src/mono/mono/mini/mini-posix.c

@@ -390,6 +390,8 @@ mono_runtime_posix_install_handlers (void)
 	sigaddset (&signal_set, SIGFPE);
 	add_signal_handler (SIGQUIT, sigquit_signal_handler, SA_RESTART);
 	sigaddset (&signal_set, SIGQUIT);
+	add_signal_handler (SIGTERM, mono_sigterm_signal_handler, SA_RESTART);
+	sigaddset (&signal_set, SIGTERM);
 	add_signal_handler (SIGILL, mono_crashing_signal_handler, 0);
 	sigaddset (&signal_set, SIGILL);
 	add_signal_handler (SIGBUS, mono_sigsegv_signal_handler, 0);

src/mono/mono/mini/mini-runtime.c

@@ -119,6 +119,7 @@ const char *mono_build_date;
 gboolean mono_do_signal_chaining;
 gboolean mono_do_crash_chaining;
 int mini_verbose = 0;
+gboolean mono_term_signaled = FALSE;
 
 /*
  * This flag controls whenever the runtime uses LLVM for JIT compilation, and whenever
@@ -3758,6 +3759,17 @@ MONO_SIG_HANDLER_FUNC (, mono_crashing_signal_handler)
 	}
 }
 
+MONO_SIG_HANDLER_FUNC (, mono_sigterm_signal_handler)
+{
+	mono_environment_exitcode_set(128+SIGTERM);	/* Set default exit code */
+
+	mono_term_signaled = TRUE;
+
+	mono_gc_finalize_notify ();
+
+	mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
+}
+
 #if defined(MONO_ARCH_USE_SIGACTION) || defined(HOST_WIN32)
 
 #define HAVE_SIG_INFO

src/mono/mono/mini/mini-runtime.h

@@ -676,6 +676,7 @@ void MONO_SIG_HANDLER_SIGNATURE (mono_sigfpe_signal_handler) ;
 void MONO_SIG_HANDLER_SIGNATURE (mono_crashing_signal_handler) ;
 void MONO_SIG_HANDLER_SIGNATURE (mono_sigsegv_signal_handler);
 void MONO_SIG_HANDLER_SIGNATURE (mono_sigint_signal_handler) ;
+void MONO_SIG_HANDLER_SIGNATURE (mono_sigterm_signal_handler) ;
 gboolean MONO_SIG_HANDLER_SIGNATURE (mono_chain_signal);
 
 #if defined (HOST_WASM)

src/mono/mono/mini/mini-windows.c

@@ -188,6 +188,7 @@ mono_runtime_install_handlers (void)
 	win32_seh_set_handler(SIGFPE, mono_sigfpe_signal_handler);
 	win32_seh_set_handler(SIGILL, mono_crashing_signal_handler);
 	win32_seh_set_handler(SIGSEGV, mono_sigsegv_signal_handler);
+	win32_seh_set_handler(SIGTERM, mono_sigterm_signal_handler);
 	if (mini_debug_options.handle_sigint)
 		win32_seh_set_handler(SIGINT, mono_sigint_signal_handler);
 #endif