[Python-checkins] bpo-26491 Defer DECREFs until enumobject is in a consistent state (#3747)

Mon Sep 25 05:15:57 EDT 2017

https://github.com/python/cpython/commit/8110dbd470f3daa4de58dda66d360e3c26d3b94f
commit: 8110dbd470f3daa4de58dda66d360e3c26d3b94f
branch: master
author: Raymond Hettinger <rhettinger at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2017年09月25日T02:15:53-07:00
summary:
bpo-26491 Defer DECREFs until enumobject is in a consistent state (#3747)
files:
M Objects/enumobject.c

diff --git a/Objects/enumobject.c b/Objects/enumobject.c
index 3eb1736200c..154d901e86d 100644
--- a/Objects/enumobject.c
+++ b/Objects/enumobject.c
@@ -103,6 +103,8 @@ enum_next_long(enumobject *en, PyObject* next_item)
 PyObject *result = en->en_result;
 PyObject *next_index;
 PyObject *stepped_up;
+ PyObject *old_index;
+ PyObject *old_item;
 
 if (en->en_longindex == NULL) {
 en->en_longindex = PyLong_FromSsize_t(PY_SSIZE_T_MAX);
@@ -118,15 +120,19 @@ enum_next_long(enumobject *en, PyObject* next_item)
 
 if (result->ob_refcnt == 1) {
 Py_INCREF(result);
- Py_DECREF(PyTuple_GET_ITEM(result, 0));
- Py_DECREF(PyTuple_GET_ITEM(result, 1));
- } else {
- result = PyTuple_New(2);
- if (result == NULL) {
- Py_DECREF(next_index);
- Py_DECREF(next_item);
- return NULL;
- }
+ old_index = PyTuple_GET_ITEM(result, 0);
+ old_item = PyTuple_GET_ITEM(result, 1);
+ PyTuple_SET_ITEM(result, 0, next_index);
+ PyTuple_SET_ITEM(result, 1, next_item);
+ Py_DECREF(old_index);
+ Py_DECREF(old_item);
+ return result;
+ }
+ result = PyTuple_New(2);
+ if (result == NULL) {
+ Py_DECREF(next_index);
+ Py_DECREF(next_item);
+ return NULL;
 }
 PyTuple_SET_ITEM(result, 0, next_index);
 PyTuple_SET_ITEM(result, 1, next_item);
@@ -140,6 +146,8 @@ enum_next(enumobject *en)
 PyObject *next_item;
 PyObject *result = en->en_result;
 PyObject *it = en->en_sit;
+ PyObject *old_index;
+ PyObject *old_item;
 
 next_item = (*Py_TYPE(it)->tp_iternext)(it);
 if (next_item == NULL)
@@ -157,15 +165,19 @@ enum_next(enumobject *en)
 
 if (result->ob_refcnt == 1) {
 Py_INCREF(result);
- Py_DECREF(PyTuple_GET_ITEM(result, 0));
- Py_DECREF(PyTuple_GET_ITEM(result, 1));
- } else {
- result = PyTuple_New(2);
- if (result == NULL) {
- Py_DECREF(next_index);
- Py_DECREF(next_item);
- return NULL;
- }
+ old_index = PyTuple_GET_ITEM(result, 0);
+ old_item = PyTuple_GET_ITEM(result, 1);
+ PyTuple_SET_ITEM(result, 0, next_index);
+ PyTuple_SET_ITEM(result, 1, next_item);
+ Py_DECREF(old_index);
+ Py_DECREF(old_item);
+ return result;
+ }
+ result = PyTuple_New(2);
+ if (result == NULL) {
+ Py_DECREF(next_index);
+ Py_DECREF(next_item);
+ return NULL;
 }
 PyTuple_SET_ITEM(result, 0, next_index);
 PyTuple_SET_ITEM(result, 1, next_item);
