https://github.com/python/cpython/commit/0b541f64c472976b2fee1ec9919bc7b02a798242
commit: 0b541f64c472976b2fee1ec9919bc7b02a798242
branch: main
author: Sheidan <[email protected]>
committer: serhiy-storchaka <[email protected]>
date: 2024-01-17T18:20:39Z
summary:
gh-105102: Fix nested unions in structures when the system byteorder is the
opposite (GH-105106)
files:
A Misc/NEWS.d/next/Library/2023-05-30-18-30-11.gh-issue-105102.SnpK04.rst
M Lib/ctypes/_endian.py
M Lib/test/test_ctypes/test_byteswap.py
diff --git a/Lib/ctypes/_endian.py b/Lib/ctypes/_endian.py
index 3febb3118b8230..6382dd22b8acc8 100644
--- a/Lib/ctypes/_endian.py
+++ b/Lib/ctypes/_endian.py
@@ -15,8 +15,8 @@ def _other_endian(typ):
# if typ is array
if isinstance(typ, _array_type):
return _other_endian(typ._type_) * typ._length_
- # if typ is structure
- if issubclass(typ, Structure):
+ # if typ is structure or union
+ if issubclass(typ, (Structure, Union)):
return typ
raise TypeError("This type does not support other endian: %s" % typ)
diff --git a/Lib/test/test_ctypes/test_byteswap.py
b/Lib/test/test_ctypes/test_byteswap.py
index b97b57646ecd71..78eff0392c4548 100644
--- a/Lib/test/test_ctypes/test_byteswap.py
+++ b/Lib/test/test_ctypes/test_byteswap.py
@@ -363,6 +363,24 @@ class TestUnion(parent):
self.assertEqual(s.point.x, 1)
self.assertEqual(s.point.y, 2)
+ def test_build_struct_union_opposite_system_byteorder(self):
+ # gh-105102
+ if sys.byteorder == "little":
+ _Structure = BigEndianStructure
+ _Union = BigEndianUnion
+ else:
+ _Structure = LittleEndianStructure
+ _Union = LittleEndianUnion
+
+ class S1(_Structure):
+ _fields_ = [("a", c_byte), ("b", c_byte)]
+
+ class U1(_Union):
+ _fields_ = [("s1", S1), ("ab", c_short)]
+
+ class S2(_Structure):
+ _fields_ = [("u1", U1), ("c", c_byte)]
+
if __name__ == "__main__":
unittest.main()
diff --git
a/Misc/NEWS.d/next/Library/2023-05-30-18-30-11.gh-issue-105102.SnpK04.rst
b/Misc/NEWS.d/next/Library/2023-05-30-18-30-11.gh-issue-105102.SnpK04.rst
new file mode 100644
index 00000000000000..7ca21afefa3132
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-05-30-18-30-11.gh-issue-105102.SnpK04.rst
@@ -0,0 +1,2 @@
+Allow :class:`ctypes.Union` to be nested in :class:`ctypes.Structure` when
+the system endianness is the opposite of the classes.
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