gh-135075: Make PyObject_SetAttr() fail with NULL value and exception

Doc/c-api/object.rst

@@ -201,6 +201,9 @@ Object Protocol
    This case can arise from forgetting ``NULL`` checks and would delete the
    attribute.
 
+   .. versionchanged:: next
+      Raise an exception if called with ``NULL`` *v* and an an exception set.
+
 
 .. c:function:: int PyObject_SetAttrString(PyObject *o, const char *attr_name, PyObject *v)
 
@@ -223,6 +226,9 @@ Object Protocol
    For more details, see :c:func:`PyUnicode_InternFromString`, which may be
    used internally to create a key object.
 
+   .. versionchanged:: next
+      Raise an exception if called with ``NULL`` *v* and an an exception set.
+
 .. c:function:: int PyObject_GenericSetAttr(PyObject *o, PyObject *name, PyObject *value)
 
    Generic attribute setter and deleter function that is meant

Lib/test/test_capi/test_object.py

@@ -251,15 +251,27 @@ def test_object_setattr_null_exc(self):
         class Obj:
             pass
         obj = Obj()
-
         obj.attr = 123
-        with self.assertRaises(SystemError):
-            _testcapi.object_setattr_null_exc(obj, 'attr')
-        self.assertTrue(hasattr(obj, 'attr'))
 
-        with self.assertRaises(SystemError):
-            _testcapi.object_setattrstring_null_exc(obj, 'attr')
-        self.assertTrue(hasattr(obj, 'attr'))
+        exc = ValueError("error")
+        with self.assertRaises(SystemError) as cm:
+            _testcapi.object_setattr_null_exc(obj, 'attr', exc)
+        self.assertIs(cm.exception.__context__, exc)
+        self.assertIsNone(cm.exception.__cause__)
+        self.assertHasAttr(obj, 'attr')
+
+        with self.assertRaises(SystemError) as cm:
+            _testcapi.object_setattrstring_null_exc(obj, 'attr', exc)
+        self.assertIs(cm.exception.__context__, exc)
+        self.assertIsNone(cm.exception.__cause__)
+        self.assertHasAttr(obj, 'attr')
+
+        with self.assertRaises(SystemError) as cm:
+            # undecodable name
+            _testcapi.object_setattrstring_null_exc(obj, b'\xff', exc)
+        self.assertIs(cm.exception.__context__, exc)
+        self.assertIsNone(cm.exception.__cause__)
+        self.assertHasAttr(obj, 'attr')
 
 
 if __name__ == "__main__":

Modules/_testcapi/abstract.c

@@ -178,6 +178,42 @@ sequence_fast_get_item(PyObject *self, PyObject *args)
 }
 
 
+static PyObject *
+object_setattr_null_exc(PyObject *self, PyObject *args)
+{
+    PyObject *obj, *name, *exc;
+    if (!PyArg_ParseTuple(args, "OOO", &obj, &name, &exc)) {
+        return NULL;
+    }
+
+    PyErr_SetObject((PyObject*)Py_TYPE(exc), exc);
+    if (PyObject_SetAttr(obj, name, NULL) < 0) {
+        return NULL;
+    }
+    assert(PyErr_Occurred());
+    return NULL;
+}
+
+
+static PyObject *
+object_setattrstring_null_exc(PyObject *self, PyObject *args)
+{
+    PyObject *obj, *exc;
+    const char *name;
+    Py_ssize_t size;
+    if (!PyArg_ParseTuple(args, "Oz#O", &obj, &name, &size, &exc)) {
+        return NULL;
+    }
+
+    PyErr_SetObject((PyObject*)Py_TYPE(exc), exc);
+    if (PyObject_SetAttrString(obj, name, NULL) < 0) {
+        return NULL;
+    }
+    assert(PyErr_Occurred());
+    return NULL;
+}
+
+
 static PyMethodDef test_methods[] = {
     {"object_getoptionalattr", object_getoptionalattr, METH_VARARGS},
     {"object_getoptionalattrstring", object_getoptionalattrstring, METH_VARARGS},
@@ -191,6 +227,8 @@ static PyMethodDef test_methods[] = {
 
     {"sequence_fast_get_size", sequence_fast_get_size, METH_O},
     {"sequence_fast_get_item", sequence_fast_get_item, METH_VARARGS},
+    {"object_setattr_null_exc", object_setattr_null_exc, METH_VARARGS},
+    {"object_setattrstring_null_exc", object_setattrstring_null_exc, METH_VARARGS},
     {NULL},
 };
 

Modules/_testcapi/object.c

@@ -485,41 +485,6 @@ is_uniquely_referenced(PyObject *self, PyObject *op)
 }
 
 
-static PyObject *
-object_setattr_null_exc(PyObject *self, PyObject *args)
-{
-    PyObject *obj, *name;
-    if (!PyArg_ParseTuple(args, "OO", &obj, &name)) {
-        return NULL;
-    }
-
-    PyErr_SetString(PyExc_ValueError, "error");
-    if (PyObject_SetAttr(obj, name, NULL) < 0) {
-        return NULL;
-    }
-    assert(PyErr_Occurred());
-    return NULL;
-}
-
-
-static PyObject *
-object_setattrstring_null_exc(PyObject *self, PyObject *args)
-{
-    PyObject *obj;
-    const char *name;
-    if (!PyArg_ParseTuple(args, "Os", &obj, &name)) {
-        return NULL;
-    }
-
-    PyErr_SetString(PyExc_ValueError, "error");
-    if (PyObject_SetAttrString(obj, name, NULL) < 0) {
-        return NULL;
-    }
-    assert(PyErr_Occurred());
-    return NULL;
-}
-
-
 static PyMethodDef test_methods[] = {
     {"call_pyobject_print", call_pyobject_print, METH_VARARGS},
     {"pyobject_print_null", pyobject_print_null, METH_VARARGS},
@@ -546,8 +511,6 @@ static PyMethodDef test_methods[] = {
     {"test_py_is_funcs", test_py_is_funcs, METH_NOARGS},
     {"clear_managed_dict", clear_managed_dict, METH_O, NULL},
     {"is_uniquely_referenced", is_uniquely_referenced, METH_O},
-    {"object_setattr_null_exc", object_setattr_null_exc, METH_VARARGS},
-    {"object_setattrstring_null_exc", object_setattrstring_null_exc, METH_VARARGS},
     {NULL},
 };