Make sure that the current exception is always normalized.

python · markshannon · Feb 8, 2023 · Feb 6, 2023 · Feb 6, 2023 · Feb 6, 2023
commit 87889bcbbd3eab8daaad6480f4943bedd8af8743
diff --git a/Include/internal/pycore_pyerrors.h b/Include/internal/pycore_pyerrors.h
@@ -37,10 +37,16 @@ PyAPI_FUNC(void) _PyErr_Fetch(
     PyObject **value,
     PyObject **traceback);
 
+extern PyObject *
+_PyErr_Fetch1(PyThreadState *tstate);
+
 PyAPI_FUNC(int) _PyErr_ExceptionMatches(
     PyThreadState *tstate,
     PyObject *exc);
 
+void
+_PyErr_Restore1(PyThreadState *tstate, PyObject *exc);
+
 PyAPI_FUNC(void) _PyErr_Restore(
     PyThreadState *tstate,
     PyObject *type,

diff --git a/Include/pyerrors.h b/Include/pyerrors.h
@@ -18,6 +18,8 @@ PyAPI_FUNC(PyObject *) PyErr_Occurred(void);
 PyAPI_FUNC(void) PyErr_Clear(void);
 PyAPI_FUNC(void) PyErr_Fetch(PyObject **, PyObject **, PyObject **);
 PyAPI_FUNC(void) PyErr_Restore(PyObject *, PyObject *, PyObject *);
+PyAPI_FUNC(PyObject *) PyErr_Fetch1(void);
+PyAPI_FUNC(void) PyErr_Restore1(PyObject *);
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030b0000
 PyAPI_FUNC(PyObject*) PyErr_GetHandledException(void);
 PyAPI_FUNC(void) PyErr_SetHandledException(PyObject *);
@@ -51,6 +53,10 @@ PyAPI_FUNC(void) PyException_SetCause(PyObject *, PyObject *);
 PyAPI_FUNC(PyObject *) PyException_GetContext(PyObject *);
 PyAPI_FUNC(void) PyException_SetContext(PyObject *, PyObject *);
 
+
+PyAPI_FUNC(PyObject *) PyException_GetArgs(PyObject *);
+PyAPI_FUNC(void) PyException_SetArgs(PyObject *, PyObject *);
+
 /* */
 
 #define PyExceptionClass_Check(x)                                       \

@@ -347,6 +347,7 @@ def test_capi2():
                 _testcapi.raise_exception(BadException, 0)
             except RuntimeError as err:
                 exc, err, tb = sys.exc_info()
+                tb = tb.tb_next
                 co = tb.tb_frame.f_code
                 self.assertEqual(co.co_name, "__init__")
                 self.assertTrue(co.co_filename.endswith('test_exceptions.py'))
@@ -1415,8 +1416,8 @@ def gen():
     @cpython_only
     def test_recursion_normalizing_infinite_exception(self):
         # Issue #30697. Test that a RecursionError is raised when
-        # PyErr_NormalizeException() maximum recursion depth has been
-        # exceeded.
+        # maximum recursion depth has been exceeded when creating
+        # an exception
         code = """if 1:
             import _testcapi
             try:
@@ -1426,8 +1427,7 @@ def test_recursion_normalizing_infinite_exception(self):
         """
         rc, out, err = script_helper.assert_python_failure("-c", code)
         self.assertEqual(rc, 1)
-        self.assertIn(b'RecursionError: maximum recursion depth exceeded '
-                      b'while normalizing an exception', err)
+        self.assertIn(b'RecursionError: maximum recursion depth exceeded', err)
         self.assertIn(b'Done.', out)
 
 

diff --git a/Modules/_testcapi/heaptype.c b/Modules/_testcapi/heaptype.c
@@ -116,10 +116,9 @@ test_from_spec_invalid_metatype_inheritance(PyObject *self, PyObject *Py_UNUSED(
     PyObject *bases = NULL;
     PyObject *new = NULL;
     PyObject *meta_error_string = NULL;
-    PyObject *exc_type = NULL;
-    PyObject *exc_value = NULL;
-    PyObject *exc_traceback = NULL;
+    PyObject *exc = NULL;
     PyObject *result = NULL;
+    PyObject *message = NULL;
 
     metaclass_a = PyType_FromSpecWithBases(&MinimalMetaclass_spec, (PyObject*)&PyType_Type);
     if (metaclass_a == NULL) {
@@ -156,13 +155,19 @@ test_from_spec_invalid_metatype_inheritance(PyObject *self, PyObject *Py_UNUSED(
 
     // Assert that the correct exception was raised
     if (PyErr_ExceptionMatches(PyExc_TypeError)) {
-        PyErr_Fetch(&exc_type, &exc_value, &exc_traceback);
-
+        exc = PyErr_Fetch1();
+        PyObject *args = PyException_GetArgs(exc);
+        if (!PyTuple_Check(args) || PyTuple_Size(args) != 1) {
+            PyErr_SetString(PyExc_AssertionError,
+                    "TypeError args are not a one-tuple");
+            goto finally;
+        }
+        PyObject *message = Py_NewRef(PyTuple_GET_ITEM(args, 0));
         meta_error_string = PyUnicode_FromString("metaclass conflict:");
         if (meta_error_string == NULL) {
             goto finally;
         }
-        int res = PyUnicode_Contains(exc_value, meta_error_string);
+        int res = PyUnicode_Contains(message, meta_error_string);
         if (res < 0) {
             goto finally;
         }
@@ -179,9 +184,8 @@ test_from_spec_invalid_metatype_inheritance(PyObject *self, PyObject *Py_UNUSED(
     Py_XDECREF(bases);
     Py_XDECREF(new);
     Py_XDECREF(meta_error_string);
-    Py_XDECREF(exc_type);
-    Py_XDECREF(exc_value);
-    Py_XDECREF(exc_traceback);
+    Py_XDECREF(exc);
+    Py_XDECREF(message);
     Py_XDECREF(class_a);
     Py_XDECREF(class_b);
     return result;

@@ -8,6 +8,7 @@
 #include <Python.h>
 #include <stdbool.h>
 #include "pycore_ceval.h"         // _Py_EnterRecursiveCall
+#include "pycore_pyerrors.h"      // struct _PyErr_Restore1
 #include "pycore_exceptions.h"    // struct _Py_exc_state
 #include "pycore_initconfig.h"
 #include "pycore_object.h"
@@ -288,13 +289,17 @@ BaseException_set_tb(PyBaseExceptionObject *self, PyObject *tb, void *Py_UNUSED(
         PyErr_SetString(PyExc_TypeError, "__traceback__ may not be deleted");
         return -1;
     }
-    else if (!(tb == Py_None || PyTraceBack_Check(tb))) {
+    if (PyTraceBack_Check(tb)) {
+        Py_XSETREF(self->traceback, Py_NewRef(tb));
+    }
+    else if (tb == Py_None) {
+        Py_CLEAR(self->traceback);
+    }
+    else {
         PyErr_SetString(PyExc_TypeError,
                         "__traceback__ must be a traceback or None");
         return -1;
     }
-
-    Py_XSETREF(self->traceback, Py_NewRef(tb));
     return 0;
 }
 
@@ -413,6 +418,20 @@ PyException_SetContext(PyObject *self, PyObject *context)
     Py_XSETREF(_PyBaseExceptionObject_cast(self)->context, context);
 }
 
+PyObject *
+PyException_GetArgs(PyObject *self)
+{
+    PyObject *args = _PyBaseExceptionObject_cast(self)->args;
+    return Py_NewRef(args);
+}
+
+void
+PyException_SetArgs(PyObject *self, PyObject *args)
+{
+    Py_INCREF(args);
+    Py_XSETREF(_PyBaseExceptionObject_cast(self)->args, args);
+}
+
 const char *
 PyExceptionClass_Name(PyObject *ob)
 {
@@ -3188,20 +3207,19 @@ SimpleExtendsException(PyExc_Exception, ReferenceError,
 
 #define MEMERRORS_SAVE 16
 
+static PyBaseExceptionObject last_resort_memory_error;
+
 static PyObject *
-MemoryError_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+get_memory_error(int allow_allocation, PyObject *args, PyObject *kwds)
 {
     PyBaseExceptionObject *self;
-
-    /* If this is a subclass of MemoryError, don't use the freelist
-     * and just return a fresh object */
-    if (type != (PyTypeObject *) PyExc_MemoryError) {
-        return BaseException_new(type, args, kwds);
-    }
-
     struct _Py_exc_state *state = get_exc_state();
     if (state->memerrors_freelist == NULL) {
-        return BaseException_new(type, args, kwds);
+        if (!allow_allocation) {
+            return Py_NewRef(&last_resort_memory_error);
+        }
+        PyObject *result = BaseException_new((PyTypeObject *)PyExc_MemoryError, args, kwds);
+        return result;
     }
 
     /* Fetch object from freelist and revive it */
@@ -3221,6 +3239,35 @@ MemoryError_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
        return (PyObject *)self;
 }
 
+static PyBaseExceptionObject last_resort_memory_error;
+
+static PyObject *
+MemoryError_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    /* If this is a subclass of MemoryError, don't use the freelist
+     * and just return a fresh object */
+    if (type != (PyTypeObject *) PyExc_MemoryError) {
+        return BaseException_new(type, args, kwds);
+    }
+    return get_memory_error(1, args, kwds);
+}
+
+PyObject *
+_PyErr_NoMemory(PyThreadState *tstate)
+{
+    if (Py_IS_TYPE(PyExc_MemoryError, NULL)) {
+        /* PyErr_NoMemory() has been called before PyExc_MemoryError has been
+           initialized by _PyExc_Init() */
+        Py_FatalError("Out of memory and PyExc_MemoryError is not "
+                      "initialized yet");
+    }
+    PyObject *err = get_memory_error(0, NULL, NULL);
+    if (err != NULL) {
+        _PyErr_Restore1(tstate, err);
+    }
+    return NULL;
+}
+
 static void
 MemoryError_dealloc(PyBaseExceptionObject *self)
 {
@@ -3252,6 +3299,7 @@ preallocate_memerrors(void)
     /* We create enough MemoryErrors and then decref them, which will fill
        up the freelist. */
     int i;
+
     PyObject *errors[MEMERRORS_SAVE];
     for (i = 0; i < MEMERRORS_SAVE; i++) {
         errors[i] = MemoryError_new((PyTypeObject *) PyExc_MemoryError,
@@ -3291,6 +3339,9 @@ static PyTypeObject _PyExc_MemoryError = {
 };
 PyObject *PyExc_MemoryError = (PyObject *) &_PyExc_MemoryError;
 
+static PyBaseExceptionObject last_resort_memory_error = {
+    _PyObject_IMMORTAL_INIT(&_PyExc_MemoryError)
+};
 
 /*
  *    BufferError extends Exception

@@ -2905,25 +2905,23 @@ format_kwargs_error(PyThreadState *tstate, PyObject *func, PyObject *kwargs)
         }
     }
     else if (_PyErr_ExceptionMatches(tstate, PyExc_KeyError)) {
-        PyObject *exc, *val, *tb;
-        _PyErr_Fetch(tstate, &exc, &val, &tb);
-        if (val && PyTuple_Check(val) && PyTuple_GET_SIZE(val) == 1) {
+        PyObject *exc = _PyErr_Fetch1(tstate);
+        PyObject *args = ((PyBaseExceptionObject *)exc)->args;
+        if (exc && PyTuple_Check(args) && PyTuple_GET_SIZE(args) == 1) {
             _PyErr_Clear(tstate);
             PyObject *funcstr = _PyObject_FunctionStr(func);
             if (funcstr != NULL) {
-                PyObject *key = PyTuple_GET_ITEM(val, 0);
+                PyObject *key = PyTuple_GET_ITEM(args, 0);
                 _PyErr_Format(
                     tstate, PyExc_TypeError,
                     "%U got multiple values for keyword argument '%S'",
                     funcstr, key);
                 Py_DECREF(funcstr);
             }
             Py_XDECREF(exc);
-            Py_XDECREF(val);
-            Py_XDECREF(tb);
         }
         else {
-            _PyErr_Restore(tstate, exc, val, tb);
+            _PyErr_Restore1(tstate, exc);
         }
     }
 }