[Python-checkins] bpo-45711: use exc_value instead of exc_type to determine if exc_info is valid. Add more assertions. (GH-29627)
iritkatriel
webhook-mailer at python.org
Thu Nov 25 04:41:42 EST 2021
https://github.com/python/cpython/commit/c456dfafe9f9f6614fbcf2213a93707f0e101f4e
commit: c456dfafe9f9f6614fbcf2213a93707f0e101f4e
branch: main
author: Irit Katriel <1055913+iritkatriel at users.noreply.github.com>
committer: iritkatriel <1055913+iritkatriel at users.noreply.github.com>
date: 2021-11-25T09:41:28Z
summary:
bpo-45711: use exc_value instead of exc_type to determine if exc_info is valid. Add more assertions. (GH-29627)
files:
M Include/internal/pycore_pyerrors.h
M Python/ceval.c
M Python/errors.c
M Python/pystate.c
M Python/sysmodule.c
diff --git a/Include/internal/pycore_pyerrors.h b/Include/internal/pycore_pyerrors.h
index 0f4d41c7e0bab..14ea182f4f47a 100644
--- a/Include/internal/pycore_pyerrors.h
+++ b/Include/internal/pycore_pyerrors.h
@@ -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,
diff --git a/Python/ceval.c b/Python/ceval.c
index 0aec5aa7fb9b0..9beb1a4368226 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -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 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
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 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, InterpreterFrame *frame, int thr
ASSERT_EXC_TYPE_IS_REDUNDANT(type, value);
_PyErr_StackItem *exc_info = tstate->exc_info;
SET_THIRD(exc_info->exc_traceback);
- SET_SECOND(exc_info->exc_value);
+ 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;
diff --git a/Python/errors.c b/Python/errors.c
index cb3938d20856f..6e74d19b78ef3 100644
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -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);
diff --git a/Python/pystate.c b/Python/pystate.c
index 56db095d24b8a..ba14c9d8af9fb 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -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;
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 3e2091e70ab8a..13fae797b29c2 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -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);
}
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