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gh-102381: don't call watcher callback with dead object (#102382)

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Co-authored-by: T. Wouters <thomas@python.org>
This commit is contained in:
Carl Meyer 2023-03-07 17:10:58 -07:00 • committed by GitHub
parent a33ca2ad1f
commit 1e703a4733
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GPG key ID: 4AEE18F83AFDEB23
12 changed files with 243 additions and 38 deletions
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38
Objects/funcobject.c
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@ -8,6 +8,20 @@
#include "pycore_pyerrors.h" // _PyErr_Occurred()
#include "structmember.h" // PyMemberDef
static PyObject* func_repr(PyFunctionObject *op);
static const char *
func_event_name(PyFunction_WatchEvent event) {
switch (event) {
#define CASE(op) \
case PyFunction_EVENT_##op: \
return "PyFunction_EVENT_" #op;
PY_FOREACH_FUNC_EVENT(CASE)
#undef CASE
}
Py_UNREACHABLE();
}
static void
notify_func_watchers(PyInterpreterState *interp, PyFunction_WatchEvent event,
PyFunctionObject *func, PyObject *new_value)
@ -21,7 +35,21 @@ notify_func_watchers(PyInterpreterState *interp, PyFunction_WatchEvent event,
// callback must be non-null if the watcher bit is set
assert(cb != NULL);
if (cb(event, func, new_value) < 0) {
PyErr_WriteUnraisable((PyObject *) func);
// Don't risk resurrecting the func if an unraisablehook keeps a
// reference; pass a string as context.
PyObject *context = NULL;
PyObject *repr = func_repr(func);
if (repr != NULL) {
context = PyUnicode_FromFormat(
"%s watcher callback for %U",
func_event_name(event), repr);
Py_DECREF(repr);
}
if (context == NULL) {
context = Py_NewRef(Py_None);
}
PyErr_WriteUnraisable(context);
Py_DECREF(context);
}
}
i++;
@ -33,6 +61,7 @@ static inline void
handle_func_event(PyFunction_WatchEvent event, PyFunctionObject *func,
PyObject *new_value)
{
assert(Py_REFCNT(func) > 0);
PyInterpreterState *interp = _PyInterpreterState_GET();
assert(interp->_initialized);
if (interp->active_func_watchers) {
@ -766,7 +795,14 @@ func_clear(PyFunctionObject *op)
static void
func_dealloc(PyFunctionObject *op)
{
assert(Py_REFCNT(op) == 0);
Py_SET_REFCNT(op, 1);
handle_func_event(PyFunction_EVENT_DESTROY, op, NULL);
if (Py_REFCNT(op) > 1) {
Py_SET_REFCNT(op, Py_REFCNT(op) - 1);
return;
}
Py_SET_REFCNT(op, 0);
_PyObject_GC_UNTRACK(op);
if (op->func_weakreflist != NULL) {
PyObject_ClearWeakRefs((PyObject *) op);