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bpo-40334: Improvements to error-handling code in the PEG parser (GH-20003) 

The following improvements are implemented in this commit:
- `p->error_indicator` is set, in case malloc or realloc fail.
- Avoid memory leaks in the case that realloc fails.
- Call `PyErr_NoMemory()` instead of `PyErr_Format()`, because it requires no memory.

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
This commit is contained in:
Lysandros Nikolaou 2020-05-17 06:19:23 +03:00 committed by GitHub
parent 6341fc7257
commit 2c8cd06afe
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 669 additions and 386 deletions
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1022
Parser/pegen/parse.c
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33
Tools/peg_generator/pegen/c_generator.py
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@ -320,24 +320,21 @@ class CParserGenerator(ParserGenerator, GrammarVisitor):
def out_of_memory_return(
self,
expr: str,
returnval: str,
message: str = "Parser out of memory",
cleanup_code: Optional[str] = None,
) -> None:
self.print(f"if ({expr}) {{")
with self.indent():
self.print(f'PyErr_Format(PyExc_MemoryError, "{message}");')
if cleanup_code is not None:
self.print(cleanup_code)
self.print(f"return {returnval};")
self.print("p->error_indicator = 1;")
self.print("PyErr_NoMemory();");
self.print("return NULL;")
self.print(f"}}")
def out_of_memory_goto(
self, expr: str, goto_target: str, message: str = "Parser out of memory"
) -> None:
def out_of_memory_goto(self, expr: str, goto_target: str) -> None:
self.print(f"if ({expr}) {{")
with self.indent():
self.print(f'PyErr_Format(PyExc_MemoryError, "{message}");')
self.print("PyErr_NoMemory();")
self.print(f"goto {goto_target};")
self.print(f"}}")
@ -487,7 +484,7 @@ class CParserGenerator(ParserGenerator, GrammarVisitor):
rhs,
is_loop=False,
is_gather=node.is_gather(),
rulename=node.name if memoize else None,
rulename=node.name,
)
if self.debug:
self.print('fprintf(stderr, "Fail at %d: {node.name}\\n", p->mark);')
@ -515,7 +512,7 @@ class CParserGenerator(ParserGenerator, GrammarVisitor):
self.print("int _mark = p->mark;")
self.print("int _start_mark = p->mark;")
self.print("void **_children = PyMem_Malloc(sizeof(void *));")
self.out_of_memory_return(f"!_children", "NULL")
self.out_of_memory_return(f"!_children")
self.print("ssize_t _children_capacity = 1;")
self.print("ssize_t _n = 0;")
if any(alt.action and "EXTRA" in alt.action for alt in rhs.alts):
@ -524,7 +521,7 @@ class CParserGenerator(ParserGenerator, GrammarVisitor):
rhs,
is_loop=True,
is_gather=node.is_gather(),
rulename=node.name if memoize else None,
rulename=node.name,
)
if is_repeat1:
self.print("if (_n == 0 || p->error_indicator) {")
@ -533,12 +530,7 @@ class CParserGenerator(ParserGenerator, GrammarVisitor):
self.print("return NULL;")
self.print("}")
self.print("asdl_seq *_seq = _Py_asdl_seq_new(_n, p->arena);")
self.out_of_memory_return(
"!_seq",
"NULL",
message=f"asdl_seq_new {node.name}",
cleanup_code="PyMem_Free(_children);",
)
self.out_of_memory_return(f"!_seq", cleanup_code="PyMem_Free(_children);")
self.print("for (int i = 0; i < _n; i++) asdl_seq_SET(_seq, i, _children[i]);")
self.print("PyMem_Free(_children);")
if node.name:
@ -682,10 +674,9 @@ class CParserGenerator(ParserGenerator, GrammarVisitor):
self.print("if (_n == _children_capacity) {")
with self.indent():
self.print("_children_capacity *= 2;")
self.print(
"_children = PyMem_Realloc(_children, _children_capacity*sizeof(void *));"
)
self.out_of_memory_return(f"!_children", "NULL", message=f"realloc {rulename}")
self.print("void **_new_children = PyMem_Realloc(_children, _children_capacity*sizeof(void *));")
self.out_of_memory_return(f"!_new_children")
self.print("_children = _new_children;")
self.print("}")
self.print("_children[_n++] = _res;")
self.print("_mark = p->mark;")