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fix quadratic backtracking in timestamp parse regex #1308

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fix quadratic backtracking in timestamp parse regex #1308

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2 changes: 1 addition & 1 deletion arrow/parser.py
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Original file line number Diff line number Diff line change
Expand Up @@ -166,7 +166,7 @@ class DateTimeParser:
_TZ_NAME_RE: ClassVar[Pattern[str]] = re.compile(r"\w[\w+\-/]+")
# NOTE: timestamps cannot be parsed from natural language strings (by removing the ^...$) because it will
# break cases like "15 Jul 2000" and a format list (see issue #447)
_TIMESTAMP_RE: ClassVar[Pattern[str]] = re.compile(r"^\-?\d+\.?\d+$")
_TIMESTAMP_RE: ClassVar[Pattern[str]] = re.compile(r"^\-?(?:\d+\.\d+|\d{2,})$")
_TIMESTAMP_EXPANDED_RE: ClassVar[Pattern[str]] = re.compile(r"^\-?\d+$")
_TIME_RE: ClassVar[Pattern[str]] = re.compile(
r"^(\d{2})(?:\:?(\d{2}))?(?:\:?(\d{2}))?(?:([\.\,])(\d+))?$"
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9 changes: 9 additions & 0 deletions tests/test_parser.py
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Expand Up @@ -244,6 +244,15 @@ def test_parse_timestamp(self):
with pytest.raises(ParserError):
self.parser.parse(".1565982019", "X")

def test_parse_timestamp_long_invalid_input(self):
# a long digit run followed by a non-digit character used to trigger
# quadratic backtracking in the timestamp regex (_TIMESTAMP_RE)
malformed = "9" * 50000 + "!"
start = time.perf_counter()
with pytest.raises(ParserError):
self.parser.parse(malformed, "X")
assert time.perf_counter() - start < 1.0

# NOTE: negative timestamps cannot be handled by datetime on Windows
# Must use timedelta to handle them: https://stackoverflow.com/questions/36179914
@pytest.mark.skipif(
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