bpo-36389: _PyObject_IsFreed() now also detects uninitialized memory (GH-12770)
Replace _PyMem_IsFreed() function with _PyMem_IsPtrFreed() inline
function. The function is now way more efficient, it became a simple
comparison on integers, rather than a short loop. It detects also
uninitialized bytes and "forbidden bytes" filled by debug hooks
on memory allocators.
Add unit tests on _PyObject_IsFreed().
diff --git a/Lib/test/test_capi.py b/Lib/test/test_capi.py
index 7c68b2c..3cd39d4 100644
--- a/Lib/test/test_capi.py
+++ b/Lib/test/test_capi.py
@@ -526,6 +526,29 @@
code = 'import _testcapi; _testcapi.pyobject_malloc_without_gil()'
self.check_malloc_without_gil(code)
+ def check_pyobject_is_freed(self, func):
+ code = textwrap.dedent('''
+ import gc, os, sys, _testcapi
+ # Disable the GC to avoid crash on GC collection
+ gc.disable()
+ obj = _testcapi.{func}()
+ error = (_testcapi.pyobject_is_freed(obj) == False)
+ # Exit immediately to avoid a crash while deallocating
+ # the invalid object
+ os._exit(int(error))
+ ''')
+ code = code.format(func=func)
+ assert_python_ok('-c', code, PYTHONMALLOC=self.PYTHONMALLOC)
+
+ def test_pyobject_is_freed_uninitialized(self):
+ self.check_pyobject_is_freed('pyobject_uninitialized')
+
+ def test_pyobject_is_freed_forbidden_bytes(self):
+ self.check_pyobject_is_freed('pyobject_forbidden_bytes')
+
+ def test_pyobject_is_freed_free(self):
+ self.check_pyobject_is_freed('pyobject_freed')
+
class PyMemMallocDebugTests(PyMemDebugTests):
PYTHONMALLOC = 'malloc_debug'