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Fix a catastrophic backtracking bug in JavaLexer #1594

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merged 2 commits into from
Nov 9, 2020
Merged

Fix a catastrophic backtracking bug in JavaLexer #1594

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d06e8a4
JavaLexer: Demonstrate a catastrophic backtracking bug
kurtmckee Nov 9, 2020
8a505c8
JavaLexer: Fix a catastrophic backtracking bug
kurtmckee Nov 9, 2020
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9 changes: 8 additions & 1 deletion pygments/lexers/jvm.py
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,7 @@ class JavaLexer(RegexLexer):
'var'),
(r'(import(?:\s+static)?)(\s+)', bygroups(Keyword.Namespace, Text),
'import'),
(r'"(\\\\|\\"|[^"])*"', String),
(r'"', String, 'string'),
(r"'\\.'|'[^\\]'|'\\u[0-9a-fA-F]{4}'", String.Char),
(r'(\.)((?:[^\W\d]|\$)[\w$]*)', bygroups(Punctuation,
Name.Attribute)),
Expand Down Expand Up @@ -96,6 +96,13 @@ class JavaLexer(RegexLexer):
'import': [
(r'[\w.]+\*?', Name.Namespace, '#pop')
],
'string': [
(r'[^\\"]+', String),
(r'\\\\', String), # Escaped backslash
(r'\\"', String), # Escaped quote
(r'\\', String), # Bare backslash
(r'"', String, '#pop'), # Closing quote
],
}


Expand Down
25 changes: 24 additions & 1 deletion tests/test_java.py
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Expand Up @@ -7,9 +7,11 @@
:license: BSD, see LICENSE for details.
"""

import time

import pytest

from pygments.token import Text, Name, Punctuation, Keyword, Number
from pygments.token import Keyword, Name, Number, Punctuation, String, Text
from pygments.lexers import JavaLexer


Expand Down Expand Up @@ -76,3 +78,24 @@ def test_numeric_literals(lexer):
(Text, '\n')
]
assert list(lexer.get_tokens(fragment)) == tokens


@pytest.mark.parametrize(
'text',
(
'""', '"abc"', '"ひらがな"', '"123"',
'"\\\\"', '"\\t"' '"\\""',
),
)
def test_string_literals_positive_match(lexer, text):
"""Test positive matches for string literals."""
tokens = list(lexer.get_tokens_unprocessed(text))
assert all([token is String for _, token, _ in tokens])
assert ''.join([value for _, _, value in tokens]) == text


def test_string_literals_backtracking(lexer):
"""Test catastrophic backtracking for string literals."""
start_time = time.time()
list(lexer.get_tokens_unprocessed('"' + '\\' * 100))
assert time.time() - start_time < 1, 'possible backtracking bug'