[Python-checkins] bpo-34068: _io__IOBase_close_impl could call _PyObject_SetAttrId with an exception set (GH-8282). (GH-8312)

[Serhiy Storchaka]

https://github.com/python/cpython/commit/cc13016658a9ed86d0b702ab6c251ad5952a952f
commit: cc13016658a9ed86d0b702ab6c251ad5952a952f
branch: 3.6
author: Serhiy Storchaka <storchaka at gmail.com>
committer: GitHub <noreply at github.com>
date: 2018-07-17T10:33:14+03:00
summary:

bpo-34068: _io__IOBase_close_impl could call _PyObject_SetAttrId with an exception set (GH-8282). (GH-8312)

(cherry picked from commit 28f07364f066792ceee93231dbb80ae8ad98b2bb)

Co-authored-by: Zackery Spytz <zspytz at gmail.com>

files:
A Misc/NEWS.d/next/Core and Builtins/2018-07-14-08-58-46.bpo-34068.9xfM55.rst
M Lib/test/test_io.py
M Modules/_io/iobase.c

diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 88fd6ce4a6be..f306917ca7da 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -957,6 +957,16 @@ def read1(self, size):
                 self.assertSequenceEqual(buffer[result:], unused)
                 self.assertEqual(len(reader.avail), avail - result)
 
+    def test_close_assert(self):
+        class R(self.IOBase):
+            def __setattr__(self, name, value):
+                pass
+            def flush(self):
+                raise OSError()
+        f = R()
+        # This would cause an assertion failure.
+        self.assertRaises(OSError, f.close)
+
 
 class CIOTest(IOTest):
 
diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-07-14-08-58-46.bpo-34068.9xfM55.rst b/Misc/NEWS.d/next/Core and Builtins/2018-07-14-08-58-46.bpo-34068.9xfM55.rst
new file mode 100644
index 000000000000..0ed8ff91925a
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2018-07-14-08-58-46.bpo-34068.9xfM55.rst	
@@ -0,0 +1,3 @@
+In :meth:`io.IOBase.close`, ensure that the :attr:`~io.IOBase.closed`
+attribute is not set with a live exception.  Patch by Zackery Spytz and Serhiy
+Storchaka.
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
index c8642040ae42..f5c82c14096c 100644
--- a/Modules/_io/iobase.c
+++ b/Modules/_io/iobase.c
@@ -210,16 +210,19 @@ static PyObject *
 _io__IOBase_close_impl(PyObject *self)
 /*[clinic end generated code: output=63c6a6f57d783d6d input=f4494d5c31dbc6b7]*/
 {
-    PyObject *res;
+    PyObject *res, *exc, *val, *tb;
+    int rc;
 
     if (IS_CLOSED(self))
         Py_RETURN_NONE;
 
     res = PyObject_CallMethodObjArgs(self, _PyIO_str_flush, NULL);
 
-    if (_PyObject_SetAttrId(self, &PyId___IOBase_closed, Py_True) < 0) {
-        Py_XDECREF(res);
-        return NULL;
+    PyErr_Fetch(&exc, &val, &tb);
+    rc = _PyObject_SetAttrId(self, &PyId___IOBase_closed, Py_True);
+    _PyErr_ChainExceptions(exc, val, tb);
+    if (rc < 0) {
+        Py_CLEAR(res);
     }
 
     if (res == NULL)