bpo-45711: use exc_value instead of exc_type to determine if exc_info is valid. Add...

diff --git a/Include/internal/pycore_pyerrors.h b/Include/internal/pycore_pyerrors.h
index 0f4d41c7e0bab8e368a0e9e1909f97fb15c78d00..14ea182f4f47aa5620486231415eb2522a514f4e 100644 (file)
--- 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 0aec5aa7fb9b0164eb128f5432c6c31cf1c3c825..9beb1a4368226c3ae5022b7ac4035069b0805247 100644 (file)
--- 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 @@ 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);
-            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 cb3938d20856fc23da8c330a389ae86defe20ea7..6e74d19b78ef338cf02536848ba22f314dc7034d 100644 (file)
--- 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 56db095d24b8ab94f98d721f912b6c9458352452..ba14c9d8af9fb707156ca50ff0cc462b8fd98a40 100644 (file)
--- 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 3e2091e70ab8a6e0fe0a9e707cd986d7ecc6b8c5..13fae797b29c2ca5c61e16adc1fa088585252c72 100644 (file)
--- 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);
 }