backport of ee5a8cf9, still under the mit x11 license.

mono/mini/exceptions-amd64.c

@@ -38,10 +38,12 @@ static MonoW32ExceptionHandler fpe_handler;
 static MonoW32ExceptionHandler ill_handler;
 static MonoW32ExceptionHandler segv_handler;
 
-static LPTOP_LEVEL_EXCEPTION_FILTER old_handler;
+LPTOP_LEVEL_EXCEPTION_FILTER mono_old_win_toplevel_exception_filter;
+guint64 mono_win_chained_exception_filter_result;
+gboolean mono_win_chained_exception_filter_didrun;
 
 #define W32_SEH_HANDLE_EX(_ex) \
-	if (_ex##_handler) _ex##_handler(0, er, sctx)
+	if (_ex##_handler) _ex##_handler(0, ep, sctx)
 
 /*
  * Unhandled Exception Filter
@@ -54,6 +56,7 @@ LONG CALLBACK seh_handler(EXCEPTION_POINTERS* ep)
 	MonoContext* sctx;
 	LONG res;
 
+	mono_win_chained_exception_filter_didrun = FALSE;
 	res = EXCEPTION_CONTINUE_EXECUTION;
 
 	er = ep->ExceptionRecord;
@@ -114,17 +117,20 @@ LONG CALLBACK seh_handler(EXCEPTION_POINTERS* ep)
 
 	g_free (sctx);
 
+	if (mono_win_chained_exception_filter_didrun)
+		res = mono_win_chained_exception_filter_result;
+
 	return res;
 }
 
 void win32_seh_init()
 {
-	old_handler = SetUnhandledExceptionFilter(seh_handler);
+	mono_old_win_toplevel_exception_filter = SetUnhandledExceptionFilter(seh_handler);
 }
 
 void win32_seh_cleanup()
 {
-	if (old_handler) SetUnhandledExceptionFilter(old_handler);
+	if (mono_old_win_toplevel_exception_filter) SetUnhandledExceptionFilter(mono_old_win_toplevel_exception_filter);
 }
 
 void win32_seh_set_handler(int type, MonoW32ExceptionHandler handler)

mono/mini/exceptions-x86.c

@@ -39,14 +39,16 @@ static MonoW32ExceptionHandler fpe_handler;
 static MonoW32ExceptionHandler ill_handler;
 static MonoW32ExceptionHandler segv_handler;
 
-static LPTOP_LEVEL_EXCEPTION_FILTER old_handler;
+LPTOP_LEVEL_EXCEPTION_FILTER mono_old_win_toplevel_exception_filter;
+guint64 mono_win_chained_exception_filter_result;
+gboolean mono_win_chained_exception_filter_didrun;
 
 #ifndef PROCESS_CALLBACK_FILTER_ENABLED
 #	define PROCESS_CALLBACK_FILTER_ENABLED 1
 #endif
 
 #define W32_SEH_HANDLE_EX(_ex) \
-	if (_ex##_handler) _ex##_handler(0, er, sctx)
+	if (_ex##_handler) _ex##_handler(0, ep, sctx)
 
 /*
  * mono_win32_get_handle_stackoverflow (void):
@@ -176,6 +178,7 @@ LONG CALLBACK seh_handler(EXCEPTION_POINTERS* ep)
 	struct sigcontext* sctx;
 	LONG res;
 
+	mono_win_chained_exception_filter_didrun = FALSE;
 	res = EXCEPTION_CONTINUE_EXECUTION;
 
 	er = ep->ExceptionRecord;
@@ -228,6 +231,9 @@ LONG CALLBACK seh_handler(EXCEPTION_POINTERS* ep)
 
 	g_free (sctx);
 
+	if (mono_win_chained_exception_filter_didrun)
+		res = mono_win_chained_exception_filter_result;
+
 	return res;
 }
 
@@ -237,12 +243,12 @@ void win32_seh_init()
 	if (!restore_stack)
 		restore_stack = mono_win32_get_handle_stackoverflow ();
 
-	old_handler = SetUnhandledExceptionFilter(seh_handler);
+	mono_old_win_toplevel_exception_filter = SetUnhandledExceptionFilter(seh_handler);
 }
 
 void win32_seh_cleanup()
 {
-	if (old_handler) SetUnhandledExceptionFilter(old_handler);
+	if (mono_old_win_toplevel_exception_filter) SetUnhandledExceptionFilter(mono_old_win_toplevel_exception_filter);
 }
 
 void win32_seh_set_handler(int type, MonoW32ExceptionHandler handler)

mono/mini/mini-windows.c

@@ -50,6 +50,10 @@
 
 #include "jit-icalls.h"
 
+extern LPTOP_LEVEL_EXCEPTION_FILTER mono_old_win_toplevel_exception_filter;
+extern guint64 mono_win_chained_exception_filter_result;
+extern gboolean mono_win_chained_exception_filter_didrun;
+
 void
 mono_runtime_install_handlers (void)
 {
@@ -71,9 +75,24 @@ mono_runtime_cleanup_handlers (void)
 #endif
 }
 
+
+/* mono_chain_signal:
+ *
+ *   Call the original signal handler for the signal given by the arguments, which
+ * should be the same as for a signal handler. Returns TRUE if the original handler
+ * was called, false otherwise.
+ */
 gboolean
 SIG_HANDLER_SIGNATURE (mono_chain_signal)
 {
+	int signal = _dummy;
+	GET_CONTEXT;
+
+	if (mono_old_win_toplevel_exception_filter) {
+		mono_win_chained_exception_filter_didrun = TRUE;
+		mono_win_chained_exception_filter_result = (*mono_old_win_toplevel_exception_filter)(info);
+		return TRUE;
+	}
 	return FALSE;
 }
 

mono/mini/mini-x86.c

@@ -6444,7 +6444,8 @@ gboolean
 mono_arch_is_single_step_event (void *info, void *sigctx)
 {
 #ifdef TARGET_WIN32
-	EXCEPTION_RECORD* einfo = (EXCEPTION_RECORD*)info;	/* Sometimes the address is off by 4 */
+	EXCEPTION_RECORD* einfo = ((EXCEPTION_POINTERS*)info)->ExceptionRecord;	/* Sometimes the address is off by 4 */
+
 	if ((einfo->ExceptionInformation[1] >= ss_trigger_page && (guint8*)einfo->ExceptionInformation[1] <= (guint8*)ss_trigger_page + 128))
 		return TRUE;
 	else
@@ -6463,7 +6464,7 @@ gboolean
 mono_arch_is_breakpoint_event (void *info, void *sigctx)
 {
 #ifdef TARGET_WIN32
-	EXCEPTION_RECORD* einfo = (EXCEPTION_RECORD*)info;	/* Sometimes the address is off by 4 */
+	EXCEPTION_RECORD* einfo = ((EXCEPTION_POINTERS*)info)->ExceptionRecord;	/* Sometimes the address is off by 4 */
 	if ((einfo->ExceptionInformation[1] >= bp_trigger_page && (guint8*)einfo->ExceptionInformation[1] <= (guint8*)bp_trigger_page + 128))
 		return TRUE;
 	else

mono/mini/mini-x86.h

@@ -31,7 +31,8 @@ struct sigcontext {
 	unsigned int eip;
 };
 
-typedef void (* MonoW32ExceptionHandler) (int _dummy, EXCEPTION_RECORD *info, void *context);
+typedef void (* MonoW32ExceptionHandler) (int _dummy, EXCEPTION_POINTERS *info, void *context);
+
 void win32_seh_init(void);
 void win32_seh_cleanup(void);
 void win32_seh_set_handler(int type, MonoW32ExceptionHandler handler);

mono/mini/mini.h

@@ -2421,7 +2421,7 @@ gboolean mono_gdb_render_native_backtraces (void) MONO_INTERNAL;
 #define SIG_HANDLER_SIGNATURE(ftn) ftn (int _dummy, siginfo_t *info, void *context)
 #define SIG_HANDLER_PARAMS _dummy, info, context
 #elif defined(HOST_WIN32)
-#define SIG_HANDLER_SIGNATURE(ftn) ftn (int _dummy, EXCEPTION_RECORD *info, void *context)
+#define SIG_HANDLER_SIGNATURE(ftn) ftn (int _dummy, EXCEPTION_POINTERS *info, void *context)
 #define SIG_HANDLER_PARAMS _dummy, info, context
 #elif defined(__HAIKU__)
 #define SIG_HANDLER_SIGNATURE(ftn) ftn (int _dummy, void *userData, vregs regs)