From f36f7279ae8ec87bbccc1cebffd1203a36a67e6e Mon Sep 17 00:00:00 2001 From: Jeffrey Kintscher <49998481+websurfer5@users.noreply.github.com> Date: Mon, 1 Jan 2024 08:24:24 -0800 Subject: [PATCH] gh-62260: Fix ctypes.Structure subclassing with multiple layers (GH-13374) The length field of StgDictObject for Structure class contains now the total number of items in ffi_type_pointer.elements (excluding the trailing null). The old behavior of using the number of elements in the parent class can cause the array to be truncated when it is copied, especially when there are multiple layers of subclassing. Co-authored-by: Serhiy Storchaka --- Lib/test/test_ctypes/test_structures.py | 63 ++++++++++++++++++- .../2019-05-17-07-22-33.bpo-18060.5mqTQM.rst | 2 + Modules/_ctypes/_ctypes.c | 10 +-- Modules/_ctypes/stgdict.c | 2 +- 4 files changed, 70 insertions(+), 7 deletions(-) create mode 100644 Misc/NEWS.d/next/Library/2019-05-17-07-22-33.bpo-18060.5mqTQM.rst diff --git a/Lib/test/test_ctypes/test_structures.py b/Lib/test/test_ctypes/test_structures.py index 21039f049475077..3eafc77ca70aead 100644 --- a/Lib/test/test_ctypes/test_structures.py +++ b/Lib/test/test_ctypes/test_structures.py @@ -1,5 +1,5 @@ import _ctypes_test -import platform +from platform import architecture as _architecture import struct import sys import unittest @@ -8,6 +8,7 @@ c_uint8, c_uint16, c_uint32, c_short, c_ushort, c_int, c_uint, c_long, c_ulong, c_longlong, c_ulonglong, c_float, c_double) +from ctypes.util import find_library from struct import calcsize from collections import namedtuple from test import support @@ -472,6 +473,66 @@ class X(Structure): self.assertEqual(s.first, got.first) self.assertEqual(s.second, got.second) + def _test_issue18060(self, Vector): + # The call to atan2() should succeed if the + # class fields were correctly cloned in the + # subclasses. Otherwise, it will segfault. + if sys.platform == 'win32': + libm = CDLL(find_library('msvcrt.dll')) + else: + libm = CDLL(find_library('m')) + + libm.atan2.argtypes = [Vector] + libm.atan2.restype = c_double + + arg = Vector(y=0.0, x=-1.0) + self.assertAlmostEqual(libm.atan2(arg), 3.141592653589793) + + @unittest.skipIf(_architecture() == ('64bit', 'WindowsPE'), "can't test Windows x64 build") + @unittest.skipUnless(sys.byteorder == 'little', "can't test on this platform") + def test_issue18060_a(self): + # This test case calls + # PyCStructUnionType_update_stgdict() for each + # _fields_ assignment, and PyCStgDict_clone() + # for the Mid and Vector class definitions. + class Base(Structure): + _fields_ = [('y', c_double), + ('x', c_double)] + class Mid(Base): + pass + Mid._fields_ = [] + class Vector(Mid): pass + self._test_issue18060(Vector) + + @unittest.skipIf(_architecture() == ('64bit', 'WindowsPE'), "can't test Windows x64 build") + @unittest.skipUnless(sys.byteorder == 'little', "can't test on this platform") + def test_issue18060_b(self): + # This test case calls + # PyCStructUnionType_update_stgdict() for each + # _fields_ assignment. + class Base(Structure): + _fields_ = [('y', c_double), + ('x', c_double)] + class Mid(Base): + _fields_ = [] + class Vector(Mid): + _fields_ = [] + self._test_issue18060(Vector) + + @unittest.skipIf(_architecture() == ('64bit', 'WindowsPE'), "can't test Windows x64 build") + @unittest.skipUnless(sys.byteorder == 'little', "can't test on this platform") + def test_issue18060_c(self): + # This test case calls + # PyCStructUnionType_update_stgdict() for each + # _fields_ assignment. + class Base(Structure): + _fields_ = [('y', c_double)] + class Mid(Base): + _fields_ = [] + class Vector(Mid): + _fields_ = [('x', c_double)] + self._test_issue18060(Vector) + def test_array_in_struct(self): # See bpo-22273 diff --git a/Misc/NEWS.d/next/Library/2019-05-17-07-22-33.bpo-18060.5mqTQM.rst b/Misc/NEWS.d/next/Library/2019-05-17-07-22-33.bpo-18060.5mqTQM.rst new file mode 100644 index 000000000000000..3fefbc3efb63c08 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2019-05-17-07-22-33.bpo-18060.5mqTQM.rst @@ -0,0 +1,2 @@ +Fixed a class inheritance issue that can cause segfaults when deriving two or more levels of subclasses from a base class of Structure or Union. + diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c index f909a9496b6526e..fc16b9176fd1c0a 100644 --- a/Modules/_ctypes/_ctypes.c +++ b/Modules/_ctypes/_ctypes.c @@ -4354,10 +4354,10 @@ _init_pos_args(PyObject *self, PyTypeObject *type, return index; } - for (i = 0; - i < dict->length && (i+index) < PyTuple_GET_SIZE(args); + for (i = index; + i < dict->length && i < PyTuple_GET_SIZE(args); ++i) { - PyObject *pair = PySequence_GetItem(fields, i); + PyObject *pair = PySequence_GetItem(fields, i - index); PyObject *name, *val; int res; if (!pair) @@ -4367,7 +4367,7 @@ _init_pos_args(PyObject *self, PyTypeObject *type, Py_DECREF(pair); return -1; } - val = PyTuple_GET_ITEM(args, i + index); + val = PyTuple_GET_ITEM(args, i); if (kwds) { res = PyDict_Contains(kwds, name); if (res != 0) { @@ -4388,7 +4388,7 @@ _init_pos_args(PyObject *self, PyTypeObject *type, if (res == -1) return -1; } - return index + dict->length; + return dict->length; } static int diff --git a/Modules/_ctypes/stgdict.c b/Modules/_ctypes/stgdict.c index dfdb96b0e7258a7..fb3e20e8db3e27e 100644 --- a/Modules/_ctypes/stgdict.c +++ b/Modules/_ctypes/stgdict.c @@ -695,7 +695,7 @@ PyCStructUnionType_update_stgdict(PyObject *type, PyObject *fields, int isStruct stgdict->size = aligned_size; stgdict->align = total_align; - stgdict->length = len; /* ADD ffi_ofs? */ + stgdict->length = ffi_ofs + len; /* * The value of MAX_STRUCT_SIZE depends on the platform Python is running on.