https://github.com/python/cpython/commit/02cdfc93f82fecdb7eae97a868d4ee222b9... commit: 02cdfc93f82fecdb7eae97a868d4ee222b9875d9 branch: master author: Lysandros Nikolaou <lisandrosnik@gmail.com> committer: lysnikolaou <lisandrosnik@gmail.com> date: 2020-10-31T20:31:41+02:00 summary: bpo-42218: Correctly handle errors in left-recursive rules (GH-23065) Left-recursive rules need to check for errors explicitly, since even if the rule returns NULL, the parsing might continue and lead to long-distance failures. Co-authored-by: Pablo Galindo <Pablogsal@gmail.com> files: A Misc/NEWS.d/next/Core and Builtins/2020-10-31-17-50-23.bpo-42218.Dp_Z3v.rst M Lib/test/test_syntax.py M Parser/parser.c M Tools/peg_generator/pegen/c_generator.py diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py index e89d9401f2c39..91ca1db43a74f 100644 --- a/Lib/test/test_syntax.py +++ b/Lib/test/test_syntax.py @@ -972,6 +972,14 @@ def func2(): """ self._check_error(code, "invalid syntax") + def test_invalid_line_continuation_left_recursive(self): + # Check bpo-42218: SyntaxErrors following left-recursive rules + # (t_primary_raw in this case) need to be tested explicitly + self._check_error("A.\u018a\\ ", + "unexpected character after line continuation character") + self._check_error("A.\u03bc\\\n", + "unexpected EOF while parsing") + def test_main(): support.run_unittest(SyntaxTestCase) from test import test_syntax diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-10-31-17-50-23.bpo-42218.Dp_Z3v.rst b/Misc/NEWS.d/next/Core and Builtins/2020-10-31-17-50-23.bpo-42218.Dp_Z3v.rst new file mode 100644 index 0000000000000..a38a310e4b45b --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2020-10-31-17-50-23.bpo-42218.Dp_Z3v.rst @@ -0,0 +1,3 @@ +Fixed a bug in the PEG parser that was causing crashes in debug mode. Now errors are checked +in left-recursive rules to avoid cases where such errors do not get handled in time and appear +as long-distance crashes in other places. diff --git a/Parser/parser.c b/Parser/parser.c index a882a81344cc6..48ebfe65aedaf 100644 --- a/Parser/parser.c +++ b/Parser/parser.c @@ -3461,6 +3461,8 @@ dotted_name_rule(Parser *p) } p->mark = _mark; void *_raw = dotted_name_raw(p); + if (p->error_indicator) + return NULL; if (_raw == NULL || p->mark <= _resmark) break; _resmark = p->mark; @@ -9045,6 +9047,8 @@ bitwise_or_rule(Parser *p) } p->mark = _mark; void *_raw = bitwise_or_raw(p); + if (p->error_indicator) + return NULL; if (_raw == NULL || p->mark <= _resmark) break; _resmark = p->mark; @@ -9159,6 +9163,8 @@ bitwise_xor_rule(Parser *p) } p->mark = _mark; void *_raw = bitwise_xor_raw(p); + if (p->error_indicator) + return NULL; if (_raw == NULL || p->mark <= _resmark) break; _resmark = p->mark; @@ -9273,6 +9279,8 @@ bitwise_and_rule(Parser *p) } p->mark = _mark; void *_raw = bitwise_and_raw(p); + if (p->error_indicator) + return NULL; if (_raw == NULL || p->mark <= _resmark) break; _resmark = p->mark; @@ -9387,6 +9395,8 @@ shift_expr_rule(Parser *p) } p->mark = _mark; void *_raw = shift_expr_raw(p); + if (p->error_indicator) + return NULL; if (_raw == NULL || p->mark <= _resmark) break; _resmark = p->mark; @@ -9540,6 +9550,8 @@ sum_rule(Parser *p) } p->mark = _mark; void *_raw = sum_raw(p); + if (p->error_indicator) + return NULL; if (_raw == NULL || p->mark <= _resmark) break; _resmark = p->mark; @@ -9699,6 +9711,8 @@ term_rule(Parser *p) } p->mark = _mark; void *_raw = term_raw(p); + if (p->error_indicator) + return NULL; if (_raw == NULL || p->mark <= _resmark) break; _resmark = p->mark; @@ -10303,6 +10317,8 @@ primary_rule(Parser *p) } p->mark = _mark; void *_raw = primary_raw(p); + if (p->error_indicator) + return NULL; if (_raw == NULL || p->mark <= _resmark) break; _resmark = p->mark; @@ -13943,6 +13959,8 @@ t_primary_rule(Parser *p) } p->mark = _mark; void *_raw = t_primary_raw(p); + if (p->error_indicator) + return NULL; if (_raw == NULL || p->mark <= _resmark) break; _resmark = p->mark; diff --git a/Tools/peg_generator/pegen/c_generator.py b/Tools/peg_generator/pegen/c_generator.py index 52bdb844e6bdd..6af0d3f7a2a14 100644 --- a/Tools/peg_generator/pegen/c_generator.py +++ b/Tools/peg_generator/pegen/c_generator.py @@ -502,6 +502,9 @@ def _set_up_rule_memoization(self, node: Rule, result_type: str) -> None: ) self.print("p->mark = _mark;") self.print(f"void *_raw = {node.name}_raw(p);") + self.print("if (p->error_indicator)") + with self.indent(): + self.print("return NULL;") self.print("if (_raw == NULL || p->mark <= _resmark)") with self.indent(): self.print("break;")