From 9dbf5d3bc2033940cdca35440cf08814544f81e4 Mon Sep 17 00:00:00 2001
From: Vinay Sajip <vinay_sajip@yahoo.co.uk>
Date: Sun, 12 Jan 2020 20:55:54 +0000
Subject: [PATCH] [3.7] bpo-16575: Disabled checks for union types being passed
by value. (GH-17960) (GH-17970)
Although the underlying libffi issue remains open, adding these
checks have caused problems in third-party projects which are in
widespread use. See the issue for examples.
The corresponding tests have also been skipped.
(cherry picked from commit c12440c371025bea9c3bfb94945f006c486c2c01)
---
Lib/ctypes/test/test_structures.py | 3 ++-
Modules/_ctypes/_ctypes.c | 19 +++++++++++++++++++
2 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/Lib/ctypes/test/test_structures.py b/Lib/ctypes/test/test_structures.py
index c129377041f03..2eb057a9f3009 100644
--- a/Lib/ctypes/test/test_structures.py
+++ b/Lib/ctypes/test/test_structures.py
@@ -532,6 +532,7 @@ class U(Union):
self.assertEqual(f2, [0x4567, 0x0123, 0xcdef, 0x89ab,
0x3210, 0x7654, 0xba98, 0xfedc])
+ @unittest.skipIf(True, 'Test disabled for now - see bpo-16575/bpo-16576')
def test_union_by_value(self):
# See bpo-16575
@@ -612,7 +613,7 @@ class Test5(Structure):
self.assertEqual(test5.nested.an_int, 0)
self.assertEqual(test5.another_int, 0)
- #@unittest.skipIf('s390' in MACHINE, 'Test causes segfault on S390')
+ @unittest.skipIf(True, 'Test disabled for now - see bpo-16575/bpo-16576')
def test_bitfield_by_value(self):
# See bpo-16576
diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
index c8fed44599543..dd0c61fd8a9a9 100644
--- a/Modules/_ctypes/_ctypes.c
+++ b/Modules/_ctypes/_ctypes.c
@@ -2277,6 +2277,23 @@ converters_from_argtypes(PyObject *ob)
for (i = 0; i < nArgs; ++i) {
PyObject *tp = PyTuple_GET_ITEM(ob, i);
PyObject *cnv;
+/*
+ * The following checks, relating to bpo-16575 and bpo-16576, have been
+ * disabled. The reason is that, although there is a definite problem with
+ * how libffi handles unions (https://github.com/libffi/libffi/issues/33),
+ * there are numerous libraries which pass structures containing unions
+ * by values - especially on Windows but examples also exist on Linux
+ * (https://bugs.python.org/msg359834).
+ *
+ * It may not be possible to get proper support for unions and bitfields
+ * until support is forthcoming in libffi, but for now, adding the checks
+ * has caused problems in otherwise-working software, which suggests it
+ * is better to disable the checks.
+ *
+ * Although specific examples reported relate specifically to unions and
+ * not bitfields, the bitfields check is also being disabled as a
+ * precaution.
+
StgDictObject *stgdict = PyType_stgdict(tp);
if (stgdict != NULL) {
@@ -2304,6 +2321,8 @@ converters_from_argtypes(PyObject *ob)
return NULL;
}
}
+ */
+
cnv = PyObject_GetAttrString(tp, "from_param");
if (!cnv)
goto argtypes_error_1;