gh-102192: Replace PyErr_Fetch/Restore etc by more efficient alternatives in _ctypes (#102477)

Author: iritkatriel

Modules/_ctypes/_ctypes.c

@@ -2200,7 +2200,6 @@ PyCSimpleType_from_param(PyObject *type, PyObject *value)
  struct fielddesc *fd;
  PyObject *as_parameter;
  int res;
- PyObject *exc, *val, *tb;
 
  /* If the value is already an instance of the requested type,
  we can use it as is */
@@ -2234,33 +2233,27 @@ PyCSimpleType_from_param(PyObject *type, PyObject *value)
  parg->obj = fd->setfunc(&parg->value, value, 0);
  if (parg->obj)
  return (PyObject *)parg;
- PyErr_Fetch(&exc, &val, &tb);
+ PyObject *exc = PyErr_GetRaisedException();
  Py_DECREF(parg);
 
  if (_PyObject_LookupAttr(value, &_Py_ID(_as_parameter_), &as_parameter) < 0) {
  Py_XDECREF(exc);
- Py_XDECREF(val);
- Py_XDECREF(tb);
  return NULL;
  }
  if (as_parameter) {
  if (_Py_EnterRecursiveCall("while processing _as_parameter_")) {
  Py_DECREF(as_parameter);
  Py_XDECREF(exc);
- Py_XDECREF(val);
- Py_XDECREF(tb);
  return NULL;
  }
  value = PyCSimpleType_from_param(type, as_parameter);
  _Py_LeaveRecursiveCall();
  Py_DECREF(as_parameter);
  Py_XDECREF(exc);
- Py_XDECREF(val);
- Py_XDECREF(tb);
  return value;
  }
  if (exc) {
- PyErr_Restore(exc, val, tb);
+ PyErr_SetRaisedException(exc);
  }
  else {
  PyErr_SetString(PyExc_TypeError, "wrong type");

Modules/_ctypes/callproc.c

@@ -1013,41 +1013,43 @@ static PyObject *GetResult(PyObject *restype, void *result, PyObject *checker)
 void _ctypes_extend_error(PyObject *exc_class, const char *fmt, ...)
 {
  va_list vargs;
- PyObject *tp, *v, *tb, *s, *cls_str, *msg_str;
 
  va_start(vargs, fmt);
- s = PyUnicode_FromFormatV(fmt, vargs);
+ PyObject *s = PyUnicode_FromFormatV(fmt, vargs);
  va_end(vargs);
- if (!s)
+ if (s == NULL) {
  return;
+ }
 
- PyErr_Fetch(&tp, &v, &tb);
- PyErr_NormalizeException(&tp, &v, &tb);
- if (PyType_Check(tp))
- cls_str = PyType_GetName((PyTypeObject *)tp);
- else
- cls_str = PyObject_Str(tp);
+ assert(PyErr_Occurred());
+ PyObject *exc = PyErr_GetRaisedException();
+ assert(exc != NULL);
+ PyObject *cls_str = PyType_GetName(Py_TYPE(exc));
  if (cls_str) {
  PyUnicode_AppendAndDel(&s, cls_str);
  PyUnicode_AppendAndDel(&s, PyUnicode_FromString(": "));
- if (s == NULL)
+ if (s == NULL) {
  goto error;
- } else
+ }
+ }
+ else {
  PyErr_Clear();
- msg_str = PyObject_Str(v);
- if (msg_str)
+ }
+
+ PyObject *msg_str = PyObject_Str(exc);
+ if (msg_str) {
  PyUnicode_AppendAndDel(&s, msg_str);
+ }
  else {
  PyErr_Clear();
  PyUnicode_AppendAndDel(&s, PyUnicode_FromString("???"));
  }
- if (s == NULL)
+ if (s == NULL) {
  goto error;
+ }
  PyErr_SetObject(exc_class, s);
 error:
- Py_XDECREF(tp);
- Py_XDECREF(v);
- Py_XDECREF(tb);
+ Py_XDECREF(exc);
  Py_XDECREF(s);
 }