Antoine Pitrou <report@bugs.python.org> wrote: > Well, if it doesn't crash, it's probably ok ;) > Perhaps check modstate->atexit_callbacks for non-NULL? > Or do we trust free() to do the right thing? I was initially surprised by this, but the docs state that it's safe: http://docs.python.org/dev/c-api/memory.html?highlight=pymem_free#PyMem_Free The I searched a bit and it appears that free() crashing on NULL is a pre-ANSI thing.
Actually _iomodule.c already has a freefunc with the same signature. atexit_free() is properly called in: static void module_dealloc(PyModuleObject *m) { PyObject_GC_UnTrack(m); if (m->md_def && m->md_def->m_free) m->md_def->m_free(m); if (m->md_dict != NULL) { _PyModule_Clear((PyObject *)m); Py_DECREF(m->md_dict); } if (m->md_state != NULL) PyMem_FREE(m->md_state); Py_TYPE(m)->tp_free((PyObject *)m); } So my only worry is if there's a way to exploit the fact that _PyModule_Clear() is called after atexit_free(). I tried things like: >>> import atexit >>> def g(): pass ... >>> class silly: ... def __del__(self): atexit.register(g) ... >>> atexit.x = silly() >>> atexit.register(g) <function g at 0x7fe7ebb83a68> >>> Exception AttributeError: "'NoneType' object has no attribute 'register'" in <bound method silly.__del__ of <__main__.silly object at 0x153fc50>> ignored But I haven't been able to break anything, so I think I'll go ahead and commit if there aren't any protests.
