bpo-45711: use exc_value instead of exc_type to determine if exc_info is valid. Add more assertions. (GH-29627)

This commit is contained in:
Irit Katriel 2021-11-25 09:41:28 +00:00 committed by GitHub
parent 24c10d2943
commit c456dfafe9
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GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 93 additions and 36 deletions

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@ -28,6 +28,8 @@ static inline void _PyErr_ClearExcState(_PyErr_StackItem *exc_state)
Py_XDECREF(tb);
}
PyAPI_FUNC(PyObject*) _PyErr_StackItemToExcInfoTuple(
_PyErr_StackItem *err_info);
PyAPI_FUNC(void) _PyErr_Fetch(
PyThreadState *tstate,

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@ -1102,7 +1102,7 @@ static void
_assert_exception_type_is_redundant(PyObject* type, PyObject* val)
{
if (type == NULL || type == Py_None) {
assert(val == NULL || val == Py_None);
assert(val == type);
}
else {
assert(PyExceptionInstance_Check(val));
@ -3738,7 +3738,9 @@ check_eval_breaker:
TARGET(JUMP_IF_NOT_EXC_MATCH) {
PyObject *right = POP();
PyObject *left = TOP();
ASSERT_EXC_TYPE_IS_REDUNDANT(TOP(), SECOND());
PyObject *left = SECOND();
assert(PyExceptionInstance_Check(left));
if (check_except_type_valid(tstate, right) < 0) {
Py_DECREF(right);
goto error;
@ -4198,7 +4200,13 @@ check_eval_breaker:
ASSERT_EXC_TYPE_IS_REDUNDANT(type, value);
_PyErr_StackItem *exc_info = tstate->exc_info;
SET_THIRD(exc_info->exc_traceback);
if (exc_info->exc_value != NULL) {
SET_SECOND(exc_info->exc_value);
}
else {
Py_INCREF(Py_None);
SET_SECOND(Py_None);
}
if (exc_info->exc_type != NULL) {
SET_TOP(exc_info->exc_type);
}
@ -5916,7 +5924,9 @@ do_raise(PyThreadState *tstate, PyObject *exc, PyObject *cause)
type = exc_info->exc_type;
value = exc_info->exc_value;
tb = exc_info->exc_traceback;
if (Py_IsNone(type) || type == NULL) {
assert(((Py_IsNone(value) || value == NULL)) ==
((Py_IsNone(type) || type == NULL)));
if (Py_IsNone(value) || value == NULL) {
_PyErr_SetString(tstate, PyExc_RuntimeError,
"No active exception to reraise");
return 0;

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@ -79,11 +79,16 @@ _PyErr_StackItem *
_PyErr_GetTopmostException(PyThreadState *tstate)
{
_PyErr_StackItem *exc_info = tstate->exc_info;
while ((exc_info->exc_type == NULL || exc_info->exc_type == Py_None) &&
assert(exc_info);
while ((exc_info->exc_value == NULL || exc_info->exc_value == Py_None) &&
exc_info->previous_item != NULL)
{
assert(exc_info->exc_type == NULL || exc_info->exc_type == Py_None);
exc_info = exc_info->previous_item;
}
assert(exc_info->previous_item == NULL ||
(exc_info->exc_type != NULL && exc_info->exc_type != Py_None));
return exc_info;
}
@ -471,10 +476,20 @@ _PyErr_GetExcInfo(PyThreadState *tstate,
PyObject **p_type, PyObject **p_value, PyObject **p_traceback)
{
_PyErr_StackItem *exc_info = _PyErr_GetTopmostException(tstate);
*p_type = exc_info->exc_type;
*p_value = exc_info->exc_value;
*p_traceback = exc_info->exc_traceback;
if (*p_value == NULL || *p_value == Py_None) {
assert(exc_info->exc_type == NULL || exc_info->exc_type == Py_None);
*p_type = Py_None;
}
else {
assert(PyExceptionInstance_Check(*p_value));
assert(exc_info->exc_type == PyExceptionInstance_Class(*p_value));
*p_type = PyExceptionInstance_Class(*p_value);
}
Py_XINCREF(*p_type);
Py_XINCREF(*p_value);
Py_XINCREF(*p_traceback);
@ -507,42 +522,66 @@ PyErr_SetExcInfo(PyObject *p_type, PyObject *p_value, PyObject *p_traceback)
Py_XDECREF(oldtraceback);
}
PyObject*
_PyErr_StackItemToExcInfoTuple(_PyErr_StackItem *err_info)
{
PyObject *exc_value = err_info->exc_value;
if (exc_value == NULL) {
exc_value = Py_None;
}
assert(exc_value == Py_None || PyExceptionInstance_Check(exc_value));
PyObject *exc_type = PyExceptionInstance_Check(exc_value) ?
PyExceptionInstance_Class(exc_value) :
Py_None;
return Py_BuildValue(
"(OOO)",
exc_type,
exc_value,
err_info->exc_traceback != NULL ?
err_info->exc_traceback : Py_None);
}
/* Like PyErr_Restore(), but if an exception is already set,
set the context associated with it.
The caller is responsible for ensuring that this call won't create
any cycles in the exception context chain. */
void
_PyErr_ChainExceptions(PyObject *exc, PyObject *val, PyObject *tb)
_PyErr_ChainExceptions(PyObject *typ, PyObject *val, PyObject *tb)
{
if (exc == NULL)
if (typ == NULL)
return;
PyThreadState *tstate = _PyThreadState_GET();
if (!PyExceptionClass_Check(exc)) {
if (!PyExceptionClass_Check(typ)) {
_PyErr_Format(tstate, PyExc_SystemError,
"_PyErr_ChainExceptions: "
"exception %R is not a BaseException subclass",
exc);
typ);
return;
}
if (_PyErr_Occurred(tstate)) {
PyObject *exc2, *val2, *tb2;
_PyErr_Fetch(tstate, &exc2, &val2, &tb2);
_PyErr_NormalizeException(tstate, &exc, &val, &tb);
PyObject *typ2, *val2, *tb2;
_PyErr_Fetch(tstate, &typ2, &val2, &tb2);
_PyErr_NormalizeException(tstate, &typ, &val, &tb);
if (tb != NULL) {
PyException_SetTraceback(val, tb);
Py_DECREF(tb);
}
Py_DECREF(exc);
_PyErr_NormalizeException(tstate, &exc2, &val2, &tb2);
Py_DECREF(typ);
_PyErr_NormalizeException(tstate, &typ2, &val2, &tb2);
PyException_SetContext(val2, val);
_PyErr_Restore(tstate, exc2, val2, tb2);
_PyErr_Restore(tstate, typ2, val2, tb2);
}
else {
_PyErr_Restore(tstate, exc, val, tb);
_PyErr_Restore(tstate, typ, val, tb);
}
}
@ -567,7 +606,11 @@ _PyErr_ChainStackItem(_PyErr_StackItem *exc_info)
} else {
exc_info_given = 1;
}
if (exc_info->exc_type == NULL || exc_info->exc_type == Py_None) {
assert( (exc_info->exc_type == NULL || exc_info->exc_type == Py_None) ==
(exc_info->exc_value == NULL || exc_info->exc_value == Py_None) );
if (exc_info->exc_value == NULL || exc_info->exc_value == Py_None) {
return;
}
@ -579,21 +622,32 @@ _PyErr_ChainStackItem(_PyErr_StackItem *exc_info)
tstate->exc_info = exc_info;
}
PyObject *exc, *val, *tb;
_PyErr_Fetch(tstate, &exc, &val, &tb);
PyObject *typ, *val, *tb;
_PyErr_Fetch(tstate, &typ, &val, &tb);
PyObject *exc2, *val2, *tb2;
exc2 = exc_info->exc_type;
PyObject *typ2, *val2, *tb2;
typ2 = exc_info->exc_type;
val2 = exc_info->exc_value;
tb2 = exc_info->exc_traceback;
_PyErr_NormalizeException(tstate, &exc2, &val2, &tb2);
#ifdef Py_DEBUG
PyObject *typ2_before = typ2;
PyObject *val2_before = val2;
PyObject *tb2_before = tb2;
#endif
_PyErr_NormalizeException(tstate, &typ2, &val2, &tb2);
#ifdef Py_DEBUG
/* exc_info should already be normalized */
assert(typ2 == typ2_before);
assert(val2 == val2_before);
assert(tb2 == tb2_before);
#endif
if (tb2 != NULL) {
PyException_SetTraceback(val2, tb2);
}
/* _PyErr_SetObject sets the context from PyThreadState. */
_PyErr_SetObject(tstate, exc, val);
Py_DECREF(exc); // since _PyErr_Occurred was true
_PyErr_SetObject(tstate, typ, val);
Py_DECREF(typ); // since _PyErr_Occurred was true
Py_XDECREF(val);
Py_XDECREF(tb);

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@ -1341,11 +1341,7 @@ _PyThread_CurrentExceptions(void)
if (id == NULL) {
goto fail;
}
PyObject *exc_info = PyTuple_Pack(
3,
err_info->exc_type != NULL ? err_info->exc_type : Py_None,
err_info->exc_value != NULL ? err_info->exc_value : Py_None,
err_info->exc_traceback != NULL ? err_info->exc_traceback : Py_None);
PyObject *exc_info = _PyErr_StackItemToExcInfoTuple(err_info);
if (exc_info == NULL) {
Py_DECREF(id);
goto fail;

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@ -785,12 +785,7 @@ sys_exc_info_impl(PyObject *module)
/*[clinic end generated code: output=3afd0940cf3a4d30 input=b5c5bf077788a3e5]*/
{
_PyErr_StackItem *err_info = _PyErr_GetTopmostException(_PyThreadState_GET());
return Py_BuildValue(
"(OOO)",
err_info->exc_type != NULL ? err_info->exc_type : Py_None,
err_info->exc_value != NULL ? err_info->exc_value : Py_None,
err_info->exc_traceback != NULL ?
err_info->exc_traceback : Py_None);
return _PyErr_StackItemToExcInfoTuple(err_info);
}