gh-97588: Fix ctypes structs

Include/internal/pycore_global_strings.h

@@ -258,6 +258,7 @@ struct _Py_global_strings {
         STRUCT_FOR_ID(_limbo)
         STRUCT_FOR_ID(_lock_unlock_module)
         STRUCT_FOR_ID(_loop)
+        STRUCT_FOR_ID(_ms_struct_)
         STRUCT_FOR_ID(_needs_com_addref_)
         STRUCT_FOR_ID(_pack_)
         STRUCT_FOR_ID(_restype_)

Lib/test/test_ctypes/test_bitfields.py

@@ -1,9 +1,10 @@
 import os
+import sys
 import unittest
 from ctypes import (CDLL, Structure, sizeof, POINTER, byref, alignment,
                     LittleEndianStructure, BigEndianStructure,
                     c_byte, c_ubyte, c_char, c_char_p, c_void_p, c_wchar,
-                    c_uint32, c_uint64,
+                    c_uint8, c_uint16, c_uint32, c_uint64,
                     c_short, c_ushort, c_int, c_uint, c_long, c_ulong, c_longlong, c_ulonglong)
 from test import support
 from test.support import import_helper
@@ -33,6 +34,30 @@ class BITS(Structure):
 func.argtypes = POINTER(BITS), c_char
 
 
+class BITS_msvc(Structure):
+    _ms_struct_ = 1
+    _fields_ = [("A", c_int, 1),
+                ("B", c_int, 2),
+                ("C", c_int, 3),
+                ("D", c_int, 4),
+                ("E", c_int, 5),
+                ("F", c_int, 6),
+                ("G", c_int, 7),
+                ("H", c_int, 8),
+                ("I", c_int, 9),
+
+                ("M", c_short, 1),
+                ("N", c_short, 2),
+                ("O", c_short, 3),
+                ("P", c_short, 4),
+                ("Q", c_short, 5),
+                ("R", c_short, 6),
+                ("S", c_short, 7)]
+
+func_msvc = CDLL(_ctypes_test.__file__).unpack_bitfields_msvc
+func_msvc.argtypes = POINTER(BITS_msvc), c_char
+
+
 class C_Test(unittest.TestCase):
 
     def test_ints(self):
@@ -42,18 +67,43 @@ def test_ints(self):
                 setattr(b, name, i)
                 self.assertEqual(getattr(b, name), func(byref(b), name.encode('ascii')))
 
-    # bpo-46913: _ctypes/cfield.c h_get() has an undefined behavior
-    @support.skip_if_sanitizer(ub=True)
     def test_shorts(self):
         b = BITS()
         name = "M"
+        # See Modules/_ctypes/_ctypes_test.c for where the magic 999 comes from.
         if func(byref(b), name.encode('ascii')) == 999:
+            # unpack_bitfields and unpack_bitfields_msvc in
+            # Modules/_ctypes/_ctypes_test.c return 999 to indicate
+            # an invalid name. 'M' is only valid, if signed short bitfields
+            # are supported by the C compiler.
             self.skipTest("Compiler does not support signed short bitfields")
         for i in range(256):
             for name in "MNOPQRS":
                 b = BITS()
                 setattr(b, name, i)
-                self.assertEqual(getattr(b, name), func(byref(b), name.encode('ascii')))
+                self.assertEqual(
+                    getattr(b, name),
+                    func(byref(b), (name.encode('ascii'))),
+                    (name, i))
+
+    def test_shorts_msvc_mode(self):
+        b = BITS_msvc()
+        name = "M"
+        # See Modules/_ctypes/_ctypes_test.c for where the magic 999 comes from.
+        if func_msvc(byref(b), name.encode('ascii')) == 999:
+            # unpack_bitfields and unpack_bitfields_msvc in
+            # Modules/_ctypes/_ctypes_test.c return 999 to indicate
+            # an invalid name. 'M' is only valid, if signed short bitfields
+            # are supported by the C compiler.
+            self.skipTest("Compiler does not support signed short bitfields")
+        for i in range(256):
+            for name in "MNOPQRS":
+                b = BITS_msvc()
+                setattr(b, name, i)
+                self.assertEqual(
+                    getattr(b, name),
+                    func_msvc(byref(b), name.encode('ascii')),
+                    (name, i))
 
 
 signed_int_types = (c_byte, c_short, c_int, c_long, c_longlong)
@@ -236,6 +286,157 @@ class X(Structure):
         else:
             self.assertEqual(sizeof(X), sizeof(c_int) * 2)
 
+    def test_mixed_5(self):
+        class X(Structure):
+            _fields_ = [
+                ('A', c_uint, 1),
+                ('B', c_ushort, 16)]
+        a = X()
+        a.A = 0
+        a.B = 1
+        self.assertEqual(1, a.B)
+
+    def test_mixed_6(self):
+        class X(Structure):
+            _fields_ = [
+                ('A', c_ulonglong, 1),
+                ('B', c_uint, 32)]
+        a = X()
+        a.A = 0
+        a.B = 1
+        self.assertEqual(1, a.B)
+
+    def test_mixed_7(self):
+        class X(Structure):
+            _fields_ = [
+                ("A", c_uint),
+                ('B', c_uint, 20),
+                ('C', c_ulonglong, 24)]
+        self.assertEqual(16, sizeof(X))
+
+    def test_mixed_8(self):
+        class Foo(Structure):
+            _fields_ = [
+                ("A", c_uint),
+                ("B", c_uint, 32),
+                ("C", c_ulonglong, 1),
+                ]
+
+        class Bar(Structure):
+            _fields_ = [
+                ("A", c_uint),
+                ("B", c_uint),
+                ("C", c_ulonglong, 1),
+                ]
+        self.assertEqual(sizeof(Foo), sizeof(Bar))
+
+    def test_mixed_9(self):
+        class X(Structure):
+            _fields_ = [
+                ("A", c_uint8),
+                ("B", c_uint, 1),
+                ]
+        if sys.platform == 'win32':
+            self.assertEqual(8, sizeof(X))
+        else:
+            self.assertEqual(4, sizeof(X))
+
+    def test_mixed_10(self):
+        class X(Structure):
+            _fields_ = [
+                ("A", c_uint32, 1),
+                ("B", c_uint64, 1),
+                ]
+        if sys.platform == 'win32':
+            self.assertEqual(8, alignment(X))
+            self.assertEqual(16, sizeof(X))
+        else:
+            self.assertEqual(8, alignment(X))
+            self.assertEqual(8, sizeof(X))
+
+    def test_gh_95496(self):
+        for field_width in range(1, 33):
+            class TestStruct(Structure):
+                _fields_ = [
+                    ("Field1", c_uint32, field_width),
+                    ("Field2", c_uint8, 8)
+                ]
+
+            cmd = TestStruct()
+            cmd.Field2 = 1
+            self.assertEqual(1, cmd.Field2)
+
+    def test_gh_84039(self):
+        class Bad(Structure):
+            _pack_ = 1
+            _fields_ = [
+                ("a0", c_uint8, 1),
+                ("a1", c_uint8, 1),
+                ("a2", c_uint8, 1),
+                ("a3", c_uint8, 1),
+                ("a4", c_uint8, 1),
+                ("a5", c_uint8, 1),
+                ("a6", c_uint8, 1),
+                ("a7", c_uint8, 1),
+                ("b0", c_uint16, 4),
+                ("b1", c_uint16, 12),
+            ]
+
+
+        class GoodA(Structure):
+            _pack_ = 1
+            _fields_ = [
+                ("a0", c_uint8, 1),
+                ("a1", c_uint8, 1),
+                ("a2", c_uint8, 1),
+                ("a3", c_uint8, 1),
+                ("a4", c_uint8, 1),
+                ("a5", c_uint8, 1),
+                ("a6", c_uint8, 1),
+                ("a7", c_uint8, 1),
+            ]
+
+
+        class Good(Structure):
+            _pack_ = 1
+            _fields_ = [
+                ("a", GoodA),
+                ("b0", c_uint16, 4),
+                ("b1", c_uint16, 12),
+            ]
+
+        self.assertEqual(3, sizeof(Bad))
+        self.assertEqual(3, sizeof(Good))
+
+    def test_gh_73939(self):
+        class MyStructure(Structure):
+            _pack_      = 1
+            _fields_    = [
+                            ("P",       c_uint16),
+                            ("L",       c_uint16, 9),
+                            ("Pro",     c_uint16, 1),
+                            ("G",       c_uint16, 1),
+                            ("IB",      c_uint16, 1),
+                            ("IR",      c_uint16, 1),
+                            ("R",       c_uint16, 3),
+                            ("T",       c_uint32, 10),
+                            ("C",       c_uint32, 20),
+                            ("R2",      c_uint32, 2)
+                        ]
+        self.assertEqual(8, sizeof(MyStructure))
+
+    def test_gh_86098(self):
+        class X(Structure):
+            _fields_ = [
+                ("a", c_uint8, 8),
+                ("b", c_uint8, 8),
+                ("c", c_uint32, 16)
+            ]
+        if sys.platform == 'win32':
+            self.assertEqual(8, sizeof(X))
+        else:
+            self.assertEqual(4, sizeof(X))
+
     def test_anon_bitfields(self):
         # anonymous bit-fields gave a strange error message
         class X(Structure):

Lib/test/test_ctypes/test_structures.py

@@ -881,6 +881,29 @@ class Test8(Union):
         self.assertEqual(ctx.exception.args[0], 'item 1 in _argtypes_ passes '
                          'a union by value, which is unsupported.')
 
+    def test_bitfield_matches_c(self):
+        class Test9(Structure):
+            _pack_ = 1
+            _fields_ = (('A', c_uint16),     # 2 bytes
+                        ('B', c_uint16, 9),
+                        ('C', c_uint16, 1),
+                        ('D', c_uint16, 1),
+                        ('E', c_uint16, 1),
+                        ('F', c_uint16, 1),
+                        ('G', c_uint16, 3),  # 4 bytes
+                        ('H', c_uint32, 10),
+                        ('I', c_uint32, 20),
+                        ('J', c_uint32, 2))  # 8 bytes
+        dll = CDLL(_ctypes_test.__file__)
+        func = dll._testfunc_bitfield_by_reference3
+        func.restype = c_long
+        func.argtypes = (POINTER(Test9),c_long,)
+        ind = 0
+        for field in Test9._fields_:
+            test9 = Test9()
+            setattr(test9,field[0], 1)
+            self.assertEqual(func(test9, ind), 1)
+            ind += 1
 
 class PointerMemberTestCase(unittest.TestCase):
 

Misc/NEWS.d/next/C API/2022-10-01-09-56-27.gh-issue-97588.Gvg54o.rst

@@ -0,0 +1 @@
+Fix ctypes construction of structs from description.