cpython/Lib/test/test_json/test_speedups.py

from test.test_json import CTest
from test.support import gc_collect


class BadBool:
    def __bool__(self):
        1/0


class TestSpeedups(CTest):
    def test_scanstring(self):
        self.assertEqual(self.json.decoder.scanstring.__module__, "_json")
        self.assertIs(self.json.decoder.scanstring, self.json.decoder.c_scanstring)

    def test_encode_basestring_ascii(self):
        self.assertEqual(self.json.encoder.encode_basestring_ascii.__module__,
                         "_json")
        self.assertIs(self.json.encoder.encode_basestring_ascii,
                      self.json.encoder.c_encode_basestring_ascii)


class TestDecode(CTest):
    def test_make_scanner(self):
        self.assertRaises(AttributeError, self.json.scanner.c_make_scanner, 1)

    def test_bad_bool_args(self):
        def test(value):
            self.json.decoder.JSONDecoder(strict=BadBool()).decode(value)
        self.assertRaises(ZeroDivisionError, test, '""')
        self.assertRaises(ZeroDivisionError, test, '{}')


class TestEncode(CTest):
    def test_make_encoder(self):
        # bpo-6986: The interpreter shouldn't crash in case c_make_encoder()
        # receives invalid arguments.
        self.assertRaises(TypeError, self.json.encoder.c_make_encoder,
            (True, False),
            b"\xCD\x7D\x3D\x4E\x12\x4C\xF9\x79\xD7\x52\xBA\x82\xF2\x27\x4A\x7D\xA0\xCA\x75",
            None)

    def test_bad_str_encoder(self):
        # Issue #31505: There shouldn't be an assertion failure in case
        # c_make_encoder() receives a bad encoder() argument.
        def bad_encoder1(*args):
            return None
        enc = self.json.encoder.c_make_encoder(None, lambda obj: str(obj),
                                               bad_encoder1, None, ': ', ', ',
                                               False, False, False)
        with self.assertRaises(TypeError):
            enc('spam', 4)
        with self.assertRaises(TypeError):
            enc({'spam': 42}, 4)

        def bad_encoder2(*args):
            1/0
        enc = self.json.encoder.c_make_encoder(None, lambda obj: str(obj),
                                               bad_encoder2, None, ': ', ', ',
                                               False, False, False)
        with self.assertRaises(ZeroDivisionError):
            enc('spam', 4)

    def test_bad_markers_argument_to_encoder(self):
        # https://bugs.python.org/issue45269
        with self.assertRaisesRegex(
            TypeError,
            r'make_encoder\(\) argument 1 must be dict or None, not int',
        ):
            self.json.encoder.c_make_encoder(1, None, None, None, ': ', ', ',
                                             False, False, False)

    def test_bad_bool_args(self):
        def test(name):
            self.json.encoder.JSONEncoder(**{name: BadBool()}).encode({'a': 1})
        self.assertRaises(ZeroDivisionError, test, 'skipkeys')
        self.assertRaises(ZeroDivisionError, test, 'ensure_ascii')
        self.assertRaises(ZeroDivisionError, test, 'check_circular')
        self.assertRaises(ZeroDivisionError, test, 'allow_nan')
        self.assertRaises(ZeroDivisionError, test, 'sort_keys')

    def test_unsortable_keys(self):
        with self.assertRaises(TypeError):
            self.json.encoder.JSONEncoder(sort_keys=True).encode({'a': 1, 1: 'a'})

    def test_mutate_dict_items_during_encode(self):
        # gh-142831: Clearing the items list via a re-entrant key encoder
        # must not cause a use-after-free.  BadDict.items() returns a
        # mutable list; encode_str clears it while iterating.
        items = None

        class BadDict(dict):
            def items(self):
                nonlocal items
                items = [("boom", object())]
                return items

        cleared = False
        def encode_str(obj):
            nonlocal items, cleared
            if items is not None:
                items.clear()
                items = None
                cleared = True
                gc_collect()
            return '"x"'

        encoder = self.json.encoder.c_make_encoder(
            None, lambda o: "null",
            encode_str, None,
            ": ", ", ", False,
            False, True
        )

        # Must not crash (use-after-free under ASan before fix)
        encoder(BadDict(real=1), 0)
        self.assertTrue(cleared)

    def test_mutate_list_during_encode(self):
        # gh-142831: Clearing a list mid-iteration via the default
        # callback must not cause a use-after-free.
        call_count = 0
        lst = [object() for _ in range(10)]

        def default(obj):
            nonlocal call_count
            call_count += 1
            if call_count == 3:
                lst.clear()
                gc_collect()
            return None

        encoder = self.json.encoder.c_make_encoder(
            None, default,
            self.json.encoder.c_encode_basestring, None,
            ": ", ", ", False,
            False, True
        )

        # Must not crash (use-after-free under ASan before fix)
        encoder(lst, 0)
        # Verify the mutation path was actually hit and the loop
        # stopped iterating after the list was cleared.
        self.assertEqual(call_count, 3)