From 8d998cb79ebea348a8f5258b642a1f772ecd93b8 Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@redhat.com>
Date: Tue, 3 Jul 2018 16:01:37 +0200
Subject: [PATCH] Fix #131: Port to Py3.7: handle tstate->exc_info

Fix Python 3.7 support: handle also tstate->exc_info, not only
tstate->exc_state.
---
 greenlet.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++--------------
 greenlet.h |  9 +++++++++
 2 files changed, 59 insertions(+), 14 deletions(-)

diff --git a/greenlet.c b/greenlet.c
index 0c85dd8..541efda 100644
--- a/greenlet.c
+++ b/greenlet.c
@@ -153,6 +153,21 @@ static PyObject* ts_empty_dict;
 #define GREENLET_tp_is_gc 0
 #endif /* !GREENLET_USE_GC */
 
+static void green_clear_exc(PyGreenlet *g)
+{
+#ifdef GREENLET_USE_EXC_INFO
+	g->exc_info = NULL;
+	g->exc_state.exc_type = NULL;
+	g->exc_state.exc_value = NULL;
+	g->exc_state.exc_traceback = NULL;
+	g->exc_state.previous_item = NULL;
+#else
+	g->exc_type = NULL;
+	g->exc_value = NULL;
+	g->exc_traceback = NULL;
+#endif
+}
+
 static PyGreenlet* green_create_main(void)
 {
 	PyGreenlet* gmain;
@@ -460,10 +475,9 @@ static int g_switchstack(void)
 		PyThreadState* tstate = PyThreadState_GET();
 		current->recursion_depth = tstate->recursion_depth;
 		current->top_frame = tstate->frame;
-#if PY_VERSION_HEX >= 0x030700A3
-		current->exc_type = tstate->exc_state.exc_type;
-		current->exc_value = tstate->exc_state.exc_value;
-		current->exc_traceback = tstate->exc_state.exc_traceback;
+#ifdef GREENLET_USE_EXC_INFO
+		current->exc_info = tstate->exc_info;
+		current->exc_state = tstate->exc_state;
 #else
 		current->exc_type = tstate->exc_type;
 		current->exc_value = tstate->exc_value;
@@ -474,9 +488,13 @@ static int g_switchstack(void)
 	if (err < 0) {   /* error */
 		PyGreenlet* current = ts_current;
 		current->top_frame = NULL;
+#ifdef GREENLET_USE_EXC_INFO
+		green_clear_exc(current);
+#else
 		current->exc_type = NULL;
 		current->exc_value = NULL;
 		current->exc_traceback = NULL;
+#endif
 
 		assert(ts_origin == NULL);
 		ts_target = NULL;
@@ -488,18 +506,20 @@ static int g_switchstack(void)
 		tstate->recursion_depth = target->recursion_depth;
 		tstate->frame = target->top_frame;
 		target->top_frame = NULL;
-#if PY_VERSION_HEX >= 0x030700A3
-		tstate->exc_state.exc_type = target->exc_type;
-		tstate->exc_state.exc_value = target->exc_value;
-		tstate->exc_state.exc_traceback = target->exc_traceback;
+#ifdef GREENLET_USE_EXC_INFO
+		tstate->exc_state = target->exc_state;
+		if (target->exc_info != NULL) {
+			tstate->exc_info = target->exc_info;
+		}
+		else {
+			tstate->exc_info = &tstate->exc_state;
+		}
 #else
 		tstate->exc_type = target->exc_type;
 		tstate->exc_value = target->exc_value;
 		tstate->exc_traceback = target->exc_traceback;
 #endif
-		target->exc_type = NULL;
-		target->exc_value = NULL;
-		target->exc_traceback = NULL;
+		green_clear_exc(target);
 
 		assert(ts_origin == NULL);
 		Py_INCREF(target);
@@ -752,9 +772,7 @@ static int GREENLET_NOINLINE(g_initialstub)(void* mark)
 		self->stack_prev = ts_current;
 	}
 	self->top_frame = NULL;
-	self->exc_type = NULL;
-	self->exc_value = NULL;
-	self->exc_traceback = NULL;
+	green_clear_exc(self);
 	self->recursion_depth = PyThreadState_GET()->recursion_depth;
 
 	/* restore arguments in case they are clobbered */
@@ -935,9 +953,15 @@ green_traverse(PyGreenlet *self, visitproc visit, void *arg)
 	   - frames are not visited: alive greenlets are not garbage collected anyway */
 	Py_VISIT((PyObject*)self->parent);
 	Py_VISIT(self->run_info);
+#ifdef GREENLET_USE_EXC_INFO
+	Py_VISIT(self->exc_state.exc_type);
+	Py_VISIT(self->exc_state.exc_value);
+	Py_VISIT(self->exc_state.exc_traceback);
+#else
 	Py_VISIT(self->exc_type);
 	Py_VISIT(self->exc_value);
 	Py_VISIT(self->exc_traceback);
+#endif
 	Py_VISIT(self->dict);
 	return 0;
 }
@@ -961,9 +985,15 @@ static int green_clear(PyGreenlet* self)
 	   so even if it switches we are relatively safe. */
 	Py_CLEAR(self->parent);
 	Py_CLEAR(self->run_info);
+#ifdef GREENLET_USE_EXC_INFO
+	Py_CLEAR(self->exc_state.exc_type);
+	Py_CLEAR(self->exc_state.exc_value);
+	Py_CLEAR(self->exc_state.exc_traceback);
+#else
 	Py_CLEAR(self->exc_type);
 	Py_CLEAR(self->exc_value);
 	Py_CLEAR(self->exc_traceback);
+#endif
 	Py_CLEAR(self->dict);
 	return 0;
 }
@@ -1030,9 +1060,15 @@ static void green_dealloc(PyGreenlet* self)
 		PyObject_ClearWeakRefs((PyObject *) self);
 	Py_CLEAR(self->parent);
 	Py_CLEAR(self->run_info);
+#ifdef GREENLET_USE_EXC_INFO
+	Py_CLEAR(self->exc_state.exc_type);
+	Py_CLEAR(self->exc_state.exc_value);
+	Py_CLEAR(self->exc_state.exc_traceback);
+#else
 	Py_CLEAR(self->exc_type);
 	Py_CLEAR(self->exc_value);
 	Py_CLEAR(self->exc_traceback);
+#endif
 	Py_CLEAR(self->dict);
 	Py_TYPE(self)->tp_free((PyObject*) self);
 }
diff --git a/greenlet.h b/greenlet.h
index 6c9b8ee..995f500 100644
--- a/greenlet.h
+++ b/greenlet.h
@@ -13,6 +13,10 @@ extern "C" {
 
 #define GREENLET_VERSION "0.4.13"
 
+#if PY_VERSION_HEX >= 0x030700A3
+#  define GREENLET_USE_EXC_INFO
+#endif
+
 typedef struct _greenlet {
 	PyObject_HEAD
 	char* stack_start;
@@ -25,9 +29,14 @@ typedef struct _greenlet {
 	struct _frame* top_frame;
 	int recursion_depth;
 	PyObject* weakreflist;
+#ifdef GREENLET_USE_EXC_INFO
+	_PyErr_StackItem *exc_info;
+	_PyErr_StackItem exc_state;
+#else
 	PyObject* exc_type;
 	PyObject* exc_value;
 	PyObject* exc_traceback;
+#endif
 	PyObject* dict;
 } PyGreenlet;