From 626bff856840f471e98ec627043f780c111a063d Mon Sep 17 00:00:00 2001 From: Victor Stinner Date: Thu, 25 Oct 2018 17:31:10 +0200 Subject: bpo-9263: Dump Python object on GC assertion failure (GH-10062) Changes: * Add _PyObject_AssertFailed() function. * Add _PyObject_ASSERT() and _PyObject_ASSERT_WITH_MSG() macros. * gc_decref(): replace assert() with _PyObject_ASSERT_WITH_MSG() to dump the faulty object if the assertion fails. _PyObject_AssertFailed() calls: * _PyMem_DumpTraceback(): try to log the traceback where the object memory has been allocated if tracemalloc is enabled. * _PyObject_Dump(): log repr(obj). * Py_FatalError(): log the current Python traceback. _PyObject_AssertFailed() uses _PyObject_IsFreed() heuristic to check if the object memory has been freed by a debug hook on Python memory allocators. Initial patch written by David Malcolm. Co-Authored-By: David Malcolm --- Modules/gcmodule.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) (limited to 'Modules/gcmodule.c') diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c index 7cddabafbc..2e19fe4b36 100644 --- a/Modules/gcmodule.c +++ b/Modules/gcmodule.c @@ -62,6 +62,12 @@ module gc // most gc_list_* functions for it. #define NEXT_MASK_UNREACHABLE (1) +/* Get an object's GC head */ +#define AS_GC(o) ((PyGC_Head *)(o)-1) + +/* Get the object given the GC head */ +#define FROM_GC(g) ((PyObject *)(((PyGC_Head *)g)+1)) + static inline int gc_is_collecting(PyGC_Head *g) { @@ -98,16 +104,12 @@ gc_reset_refs(PyGC_Head *g, Py_ssize_t refs) static inline void gc_decref(PyGC_Head *g) { - assert(gc_get_refs(g) > 0); + _PyObject_ASSERT_WITH_MSG(FROM_GC(g), + gc_get_refs(g) > 0, + "refcount is too small"); g->_gc_prev -= 1 << _PyGC_PREV_SHIFT; } -/* Get an object's GC head */ -#define AS_GC(o) ((PyGC_Head *)(o)-1) - -/* Get the object given the GC head */ -#define FROM_GC(g) ((PyObject *)(((PyGC_Head *)g)+1)) - /* Python string to use if unhandled exception occurs */ static PyObject *gc_str = NULL; -- cgit v1.2.1