cpython/Lib/test/test_structseq.py
Sam Gross 1bfb58cf2f
[3.12] gh-122527: Fix a crash on deallocation of PyStructSequence (GH-122577) (#122626)
The `PyStructSequence` destructor would crash if it was deallocated after
its type's dictionary was cleared by the GC, because it couldn't compute
the "real size" of the instance. This could occur with relatively
straightforward code in the free-threaded build or with a reference
cycle involving the type in the default build, due to differing orders
in which `tp_clear()` was called.

Account for the non-sequence fields in `tp_basicsize` and use that,
along with `Py_SIZE()`, to compute the "real" size of a
`PyStructSequence` in the dealloc function. This avoids the accesses to
the type's dictionary during dealloc, which were unsafe.
(cherry picked from commit 4b63cd170e)
2024-09-06 15:46:56 +02:00

222 lines
7.7 KiB
Python

import copy
import os
import pickle
import textwrap
import time
import unittest
from test.support import script_helper
class StructSeqTest(unittest.TestCase):
def test_tuple(self):
t = time.gmtime()
self.assertIsInstance(t, tuple)
astuple = tuple(t)
self.assertEqual(len(t), len(astuple))
self.assertEqual(t, astuple)
# Check that slicing works the same way; at one point, slicing t[i:j] with
# 0 < i < j could produce NULLs in the result.
for i in range(-len(t), len(t)):
self.assertEqual(t[i:], astuple[i:])
for j in range(-len(t), len(t)):
self.assertEqual(t[i:j], astuple[i:j])
for j in range(-len(t), len(t)):
self.assertEqual(t[:j], astuple[:j])
self.assertRaises(IndexError, t.__getitem__, -len(t)-1)
self.assertRaises(IndexError, t.__getitem__, len(t))
for i in range(-len(t), len(t)-1):
self.assertEqual(t[i], astuple[i])
def test_repr(self):
t = time.gmtime()
self.assertTrue(repr(t))
t = time.gmtime(0)
self.assertEqual(repr(t),
"time.struct_time(tm_year=1970, tm_mon=1, tm_mday=1, tm_hour=0, "
"tm_min=0, tm_sec=0, tm_wday=3, tm_yday=1, tm_isdst=0)")
# os.stat() gives a complicated struct sequence.
st = os.stat(__file__)
rep = repr(st)
self.assertTrue(rep.startswith("os.stat_result"))
self.assertIn("st_mode=", rep)
self.assertIn("st_ino=", rep)
self.assertIn("st_dev=", rep)
def test_concat(self):
t1 = time.gmtime()
t2 = t1 + tuple(t1)
for i in range(len(t1)):
self.assertEqual(t2[i], t2[i+len(t1)])
def test_repeat(self):
t1 = time.gmtime()
t2 = 3 * t1
for i in range(len(t1)):
self.assertEqual(t2[i], t2[i+len(t1)])
self.assertEqual(t2[i], t2[i+2*len(t1)])
def test_contains(self):
t1 = time.gmtime()
for item in t1:
self.assertIn(item, t1)
self.assertNotIn(-42, t1)
def test_hash(self):
t1 = time.gmtime()
self.assertEqual(hash(t1), hash(tuple(t1)))
def test_cmp(self):
t1 = time.gmtime()
t2 = type(t1)(t1)
self.assertEqual(t1, t2)
self.assertTrue(not (t1 < t2))
self.assertTrue(t1 <= t2)
self.assertTrue(not (t1 > t2))
self.assertTrue(t1 >= t2)
self.assertTrue(not (t1 != t2))
def test_fields(self):
t = time.gmtime()
self.assertEqual(len(t), t.n_sequence_fields)
self.assertEqual(t.n_unnamed_fields, 0)
self.assertEqual(t.n_fields, time._STRUCT_TM_ITEMS)
def test_constructor(self):
t = time.struct_time
self.assertRaises(TypeError, t)
self.assertRaises(TypeError, t, None)
self.assertRaises(TypeError, t, "123")
self.assertRaises(TypeError, t, "123", dict={})
self.assertRaises(TypeError, t, "123456789", dict=None)
s = "123456789"
self.assertEqual("".join(t(s)), s)
def test_eviltuple(self):
class Exc(Exception):
pass
# Devious code could crash structseqs' constructors
class C:
def __getitem__(self, i):
raise Exc
def __len__(self):
return 9
self.assertRaises(Exc, time.struct_time, C())
def test_pickling(self):
t = time.gmtime()
for proto in range(pickle.HIGHEST_PROTOCOL + 1):
p = pickle.dumps(t, proto)
t2 = pickle.loads(p)
self.assertEqual(t2.__class__, t.__class__)
self.assertEqual(t2, t)
self.assertEqual(t2.tm_year, t.tm_year)
self.assertEqual(t2.tm_zone, t.tm_zone)
def test_pickling_with_unnamed_fields(self):
assert os.stat_result.n_unnamed_fields > 0
r = os.stat_result(range(os.stat_result.n_sequence_fields),
{'st_atime': 1.0, 'st_atime_ns': 2.0})
for proto in range(pickle.HIGHEST_PROTOCOL + 1):
p = pickle.dumps(r, proto)
r2 = pickle.loads(p)
self.assertEqual(r2.__class__, r.__class__)
self.assertEqual(r2, r)
self.assertEqual(r2.st_mode, r.st_mode)
self.assertEqual(r2.st_atime, r.st_atime)
self.assertEqual(r2.st_atime_ns, r.st_atime_ns)
def test_copying(self):
n_fields = time.struct_time.n_fields
t = time.struct_time([[i] for i in range(n_fields)])
t2 = copy.copy(t)
self.assertEqual(t2.__class__, t.__class__)
self.assertEqual(t2, t)
self.assertEqual(t2.tm_year, t.tm_year)
self.assertEqual(t2.tm_zone, t.tm_zone)
self.assertIs(t2[0], t[0])
self.assertIs(t2.tm_year, t.tm_year)
t3 = copy.deepcopy(t)
self.assertEqual(t3.__class__, t.__class__)
self.assertEqual(t3, t)
self.assertEqual(t3.tm_year, t.tm_year)
self.assertEqual(t3.tm_zone, t.tm_zone)
self.assertIsNot(t3[0], t[0])
self.assertIsNot(t3.tm_year, t.tm_year)
def test_copying_with_unnamed_fields(self):
assert os.stat_result.n_unnamed_fields > 0
n_sequence_fields = os.stat_result.n_sequence_fields
r = os.stat_result([[i] for i in range(n_sequence_fields)],
{'st_atime': [1.0], 'st_atime_ns': [2.0]})
r2 = copy.copy(r)
self.assertEqual(r2.__class__, r.__class__)
self.assertEqual(r2, r)
self.assertEqual(r2.st_mode, r.st_mode)
self.assertEqual(r2.st_atime, r.st_atime)
self.assertEqual(r2.st_atime_ns, r.st_atime_ns)
self.assertIs(r2[0], r[0])
self.assertIs(r2.st_mode, r.st_mode)
self.assertIs(r2.st_atime, r.st_atime)
self.assertIs(r2.st_atime_ns, r.st_atime_ns)
r3 = copy.deepcopy(r)
self.assertEqual(r3.__class__, r.__class__)
self.assertEqual(r3, r)
self.assertEqual(r3.st_mode, r.st_mode)
self.assertEqual(r3.st_atime, r.st_atime)
self.assertEqual(r3.st_atime_ns, r.st_atime_ns)
self.assertIsNot(r3[0], r[0])
self.assertIsNot(r3.st_mode, r.st_mode)
self.assertIsNot(r3.st_atime, r.st_atime)
self.assertIsNot(r3.st_atime_ns, r.st_atime_ns)
def test_extended_getslice(self):
# Test extended slicing by comparing with list slicing.
t = time.gmtime()
L = list(t)
indices = (0, None, 1, 3, 19, 300, -1, -2, -31, -300)
for start in indices:
for stop in indices:
# Skip step 0 (invalid)
for step in indices[1:]:
self.assertEqual(list(t[start:stop:step]),
L[start:stop:step])
def test_match_args(self):
expected_args = ('tm_year', 'tm_mon', 'tm_mday', 'tm_hour', 'tm_min',
'tm_sec', 'tm_wday', 'tm_yday', 'tm_isdst')
self.assertEqual(time.struct_time.__match_args__, expected_args)
def test_match_args_with_unnamed_fields(self):
expected_args = ('st_mode', 'st_ino', 'st_dev', 'st_nlink', 'st_uid',
'st_gid', 'st_size')
self.assertEqual(os.stat_result.n_unnamed_fields, 3)
self.assertEqual(os.stat_result.__match_args__, expected_args)
def test_reference_cycle(self):
# gh-122527: Check that a structseq that's part of a reference cycle
# with its own type doesn't crash. Previously, if the type's dictionary
# was cleared first, the structseq instance would crash in the
# destructor.
script_helper.assert_python_ok("-c", textwrap.dedent(r"""
import time
t = time.gmtime()
type(t).refcyle = t
"""))
if __name__ == "__main__":
unittest.main()