Change in policy: when a slot_tp_xxx function looks for the __xxx__ method,

don't use getattr, but only look in the dict of the type and base types.
This prevents picking up all sorts of weird stuff, including things defined
by the metaclass when the object is a class (type).

For this purpose, a helper function lookup_method() was added.  One or two
other places also use this.

1 files changed, 57 insertions, 15 deletions

diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 5cc4161..7fb6c8a 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -289,6 +289,36 @@ PyType_IsSubtype(PyTypeObject *a, PyTypeObject *b)
 	}
 }
 
+/* Internal routine to do a method lookup in the type
+   without looking in the instance dictionary
+   (so we can't use PyObject_GetAttr) but still binding
+   it to the instance.  The arguments are the object,
+   the method name as a C string, and the address of a
+   static variable used to cache the interned Python string. */
+
+static PyObject *
+lookup_method(PyObject *self, char *attrstr, PyObject **attrobj)
+{
+	PyObject *res;
+
+	if (*attrobj == NULL) {
+		*attrobj = PyString_InternFromString(attrstr);
+		if (*attrobj == NULL)
+			return NULL;
+	}
+	res = _PyType_Lookup(self->ob_type, *attrobj);
+	if (res == NULL)
+		PyErr_SetObject(PyExc_AttributeError, *attrobj);
+	else {
+		descrgetfunc f;
+		if ((f = res->ob_type->tp_descr_get) == NULL)
+			Py_INCREF(res);
+		else
+			res = f(res, self, (PyObject *)(self->ob_type));
+	}
+	return res;
+}
+
 /* Method resolution order algorithm from "Putting Metaclasses to Work"
    by Forman and Danforth (Addison-Wesley 1999). */
 
@@ -399,7 +429,8 @@ mro_internal(PyTypeObject *type)
 		result = mro_implementation(type);
 	}
 	else {
-		mro = PyObject_GetAttrString((PyObject *)type, "mro");
+		static PyObject *mro_str;
+		mro = lookup_method((PyObject *)type, "mro", &mro_str);
 		if (mro == NULL)
 			return -1;
 		result = PyObject_CallObject(mro, NULL);
@@ -2405,8 +2436,9 @@ static int
 slot_sq_contains(PyObject *self, PyObject *value)
 {
 	PyObject *func, *res, *args;
+	static PyObject *contains_str;
 
-	func = PyObject_GetAttrString(self, "__contains__");
+	func = lookup_method(self, "__contains__", &contains_str);
 
 	if (func != NULL) {
 		args = Py_BuildValue("(O)", value);
@@ -2479,11 +2511,12 @@ static int
 slot_nb_nonzero(PyObject *self)
 {
 	PyObject *func, *res;
+	static PyObject *nonzero_str, *len_str;
 
-	func = PyObject_GetAttrString(self, "__nonzero__");
+	func = lookup_method(self, "__nonzero__", &nonzero_str);
 	if (func == NULL) {
 		PyErr_Clear();
-		func = PyObject_GetAttrString(self, "__len__");
+		func = lookup_method(self, "__len__", &len_str);
 	}
 
 	if (func != NULL) {
@@ -2532,9 +2565,10 @@ static int
 half_compare(PyObject *self, PyObject *other)
 {
 	PyObject *func, *args, *res;
+	static PyObject *cmp_str;
 	int c;
 
-	func = PyObject_GetAttrString(self, "__cmp__");
+	func = lookup_method(self, "__cmp__", &cmp_str);
 	if (func == NULL) {
 		PyErr_Clear();
 	}
@@ -2585,8 +2619,9 @@ static PyObject *
 slot_tp_repr(PyObject *self)
 {
 	PyObject *func, *res;
+	static PyObject *repr_str;
 
-	func = PyObject_GetAttrString(self, "__repr__");
+	func = lookup_method(self, "__repr__", &repr_str);
 	if (func != NULL) {
 		res = PyEval_CallObject(func, NULL);
 		Py_DECREF(func);
@@ -2601,8 +2636,9 @@ static PyObject *
 slot_tp_str(PyObject *self)
 {
 	PyObject *func, *res;
+	static PyObject *str_str;
 
-	func = PyObject_GetAttrString(self, "__str__");
+	func = lookup_method(self, "__str__", &str_str);
 	if (func != NULL) {
 		res = PyEval_CallObject(func, NULL);
 		Py_DECREF(func);
@@ -2618,9 +2654,11 @@ static long
 slot_tp_hash(PyObject *self)
 {
 	PyObject *func, *res;
+	static PyObject *hash_str, *eq_str, *cmp_str;
+
 	long h;
 
-	func = PyObject_GetAttrString(self, "__hash__");
+	func = lookup_method(self, "__hash__", &hash_str);
 
 	if (func != NULL) {
 		res = PyEval_CallObject(func, NULL);
@@ -2631,10 +2669,10 @@ slot_tp_hash(PyObject *self)
 	}
 	else {
 		PyErr_Clear();
-		func = PyObject_GetAttrString(self, "__eq__");
+		func = lookup_method(self, "__eq__", &eq_str);
 		if (func == NULL) {
 			PyErr_Clear();
-			func = PyObject_GetAttrString(self, "__cmp__");
+			func = lookup_method(self, "__cmp__", &cmp_str);
 		}
 		if (func != NULL) {
 			Py_DECREF(func);
@@ -2652,7 +2690,8 @@ slot_tp_hash(PyObject *self)
 static PyObject *
 slot_tp_call(PyObject *self, PyObject *args, PyObject *kwds)
 {
-	PyObject *meth = PyObject_GetAttrString(self, "__call__");
+	static PyObject *call_str;
+	PyObject *meth = lookup_method(self, "__call__", &call_str);
 	PyObject *res;
 
 	if (meth == NULL)
@@ -2714,8 +2753,9 @@ static PyObject *
 half_richcompare(PyObject *self, PyObject *other, int op)
 {
 	PyObject *func, *args, *res;
+	static PyObject *op_str[6];
 
-	func = PyObject_GetAttrString(self, name_op[op]);
+	func = lookup_method(self, name_op[op], &op_str[op]);
 	if (func == NULL) {
 		PyErr_Clear();
 		Py_INCREF(Py_NotImplemented);
@@ -2761,15 +2801,16 @@ static PyObject *
 slot_tp_iter(PyObject *self)
 {
 	PyObject *func, *res;
+	static PyObject *iter_str, *getitem_str;
 
-	func = PyObject_GetAttrString(self, "__iter__");
+	func = lookup_method(self, "__iter__", &iter_str);
 	if (func != NULL) {
 		 res = PyObject_CallObject(func, NULL);
 		 Py_DECREF(func);
 		 return res;
 	}
 	PyErr_Clear();
-	func = PyObject_GetAttrString(self, "__getitem__");
+	func = lookup_method(self, "__getitem__", &getitem_str);
 	if (func == NULL) {
 		PyErr_SetString(PyExc_TypeError, "iter() of non-sequence");
 		return NULL;
@@ -2830,7 +2871,8 @@ slot_tp_descr_set(PyObject *self, PyObject *target, PyObject *value)
 static int
 slot_tp_init(PyObject *self, PyObject *args, PyObject *kwds)
 {
-	PyObject *meth = PyObject_GetAttrString(self, "__init__");
+	static PyObject *init_str;
+	PyObject *meth = lookup_method(self, "__init__", &init_str);
 	PyObject *res;
 
 	if (meth == NULL)