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bpo-29753: revert 0d7ad9f (GH-19850) #27085

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Merged
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Jul 11, 2021
Merged

bpo-29753: revert 0d7ad9f (GH-19850) #27085

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63 changes: 0 additions & 63 deletions Lib/ctypes/test/test_bitfields.py
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Original file line number Diff line number Diff line change
Expand Up @@ -233,69 +233,6 @@ class X(Structure):
else:
self.assertEqual(sizeof(X), sizeof(c_int) * 2)

@unittest.skipIf(os.name == 'nt', reason='Posix only')
def test_packed_posix(self):
test_cases = {
(
("a", c_uint8, 4),
("b", c_uint8, 4),
): 1,
(
("a", c_uint8, 1),
("b", c_uint16, 1),
("c", c_uint32, 1),
("d", c_uint64, 1),
): 1,
(
("a", c_uint8, 8),
("b", c_uint16, 1),
("c", c_uint32, 1),
("d", c_uint64, 1),
): 2,
(
("a", c_uint32, 9),
("b", c_uint16, 10),
("c", c_uint32, 25),
("d", c_uint64, 1),
): 6,
(
("a", c_uint32, 9),
("b", c_uint16, 10),
("c", c_uint32, 25),
("d", c_uint64, 5),
): 7,
(
("a", c_uint16),
("b", c_uint16, 9),
("c", c_uint16, 1),
("d", c_uint16, 1),
("e", c_uint16, 1),
("f", c_uint16, 1),
("g", c_uint16, 3),
("h", c_uint32, 10),
("i", c_uint32, 20),
("j", c_uint32, 2),
): 8,
(
("a", c_uint16, 9),
("b", c_uint16, 10),
("d", c_uint16),
("c", c_uint8, 8),
): 6,
(
("a", c_uint32, 9),
("b", c_uint32),
("c", c_uint32, 8),
): 7,
}

for fields, size in test_cases.items():
with self.subTest(fields=fields):
class X(Structure):
_pack_ = 1
_fields_ = list(fields)
self.assertEqual(sizeof(X), size)

def test_anon_bitfields(self):
# anonymous bit-fields gave a strange error message
class X(Structure):
Expand Down
35 changes: 8 additions & 27 deletions Modules/_ctypes/cfield.c
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Original file line number Diff line number Diff line change
Expand Up @@ -71,18 +71,6 @@ PyCField_FromDesc(PyObject *desc, Py_ssize_t index,
Py_DECREF(self);
return NULL;
}

#ifndef MS_WIN32
/* if we have a packed bitfield, calculate the minimum number of bytes we
need to fit it. otherwise use the specified size. */
if (pack && bitsize) {
size = (bitsize - 1) / 8 + 1;
} else
#endif
size = dict->size;

proto = desc;

if (bitsize /* this is a bitfield request */
&& *pfield_size /* we have a bitfield open */
#ifdef MS_WIN32
Expand All @@ -99,26 +87,25 @@ PyCField_FromDesc(PyObject *desc, Py_ssize_t index,
} else if (bitsize /* this is a bitfield request */
&& *pfield_size /* we have a bitfield open */
&& dict->size * 8 >= *pfield_size
/* if this is a packed bitfield, always expand it.
otherwise calculate if we need to expand it. */
&& (((*pbitofs + bitsize) <= dict->size * 8) || pack)) {
&& (*pbitofs + bitsize) <= dict->size * 8) {
/* expand bit field */
fieldtype = EXPAND_BITFIELD;
#endif
} else if (bitsize) {
/* start new bitfield */
fieldtype = NEW_BITFIELD;
*pbitofs = 0;
/* use our calculated size (size) instead of type size (dict->size),
which can be different for packed bitfields */
*pfield_size = size * 8;
*pfield_size = dict->size * 8;
} else {
/* not a bit field */
fieldtype = NO_BITFIELD;
*pbitofs = 0;
*pfield_size = 0;
}

size = dict->size;
proto = desc;

/* Field descriptors for 'c_char * n' are be scpecial cased to
return a Python string instead of an Array object instance...
*/
Expand Down Expand Up @@ -183,16 +170,10 @@ PyCField_FromDesc(PyObject *desc, Py_ssize_t index,
break;

case EXPAND_BITFIELD:
/* increase the size if it is a packed bitfield.
EXPAND_BITFIELD should not be selected for non-packed fields if the
current size isn't already enough. */
if (pack)
size = (*pbitofs + bitsize - 1) / 8 + 1;

*poffset += size - *pfield_size/8;
*psize += size - *pfield_size/8;
*poffset += dict->size - *pfield_size/8;
*psize += dict->size - *pfield_size/8;

*pfield_size = size * 8;
*pfield_size = dict->size * 8;

if (big_endian)
self->size = (bitsize << 16) + *pfield_size - *pbitofs - bitsize;
Expand Down