Issue #24102: Fixed exception type checking in standard error handlers.

Lib/test/test_codeccallbacks.py

@@ -961,6 +961,29 @@ class CodecCallbackTest(unittest.TestCase):
                 with self.assertRaises(TypeError):
                     data.decode(encoding, "test.replacing")
 
+    def test_fake_error_class(self):
+        handlers = [
+            codecs.strict_errors,
+            codecs.ignore_errors,
+            codecs.replace_errors,
+            codecs.backslashreplace_errors,
+            codecs.xmlcharrefreplace_errors,
+            codecs.lookup_error('surrogateescape'),
+            codecs.lookup_error('surrogatepass'),
+        ]
+        for cls in UnicodeEncodeError, UnicodeDecodeError, UnicodeTranslateError:
+            class FakeUnicodeError(str):
+                __class__ = cls
+            for handler in handlers:
+                with self.subTest(handler=handler, error_class=cls):
+                    self.assertRaises(TypeError, handler, FakeUnicodeError())
+            class FakeUnicodeError(Exception):
+                __class__ = cls
+            for handler in handlers:
+                with self.subTest(handler=handler, error_class=cls):
+                    with self.assertRaises((TypeError, FakeUnicodeError)):
+                        handler(FakeUnicodeError())
+
 
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS

@@ -10,6 +10,8 @@ Release date: tba
 Core and Builtins
 -----------------
 
+- Issue #24102: Fixed exception type checking in standard error handlers.
+
 - Issue #20274: Remove ignored and erroneous "kwargs" parameters from three
   METH_VARARGS methods on _sqlite.Connection.
 

Python/codecs.c

@@ -661,18 +661,9 @@ PyObject *PyCodec_LookupError(const char *name)
 
 static void wrong_exception_type(PyObject *exc)
 {
-    _Py_IDENTIFIER(__class__);
-    _Py_IDENTIFIER(__name__);
-    PyObject *type = _PyObject_GetAttrId(exc, &PyId___class__);
-    if (type != NULL) {
-        PyObject *name = _PyObject_GetAttrId(type, &PyId___name__);
-        Py_DECREF(type);
-        if (name != NULL) {
-            PyErr_Format(PyExc_TypeError,
-                         "don't know how to handle %S in error callback", name);
-            Py_DECREF(name);
-        }
-    }
+    PyErr_Format(PyExc_TypeError,
+                 "don't know how to handle %.200s in error callback",
+                 exc->ob_type->tp_name);
 }
 
 PyObject *PyCodec_StrictErrors(PyObject *exc)
@@ -688,15 +679,16 @@ PyObject *PyCodec_StrictErrors(PyObject *exc)
 PyObject *PyCodec_IgnoreErrors(PyObject *exc)
 {
     Py_ssize_t end;
-    if (PyObject_IsInstance(exc, PyExc_UnicodeEncodeError)) {
+
+    if (PyObject_TypeCheck(exc, (PyTypeObject *)PyExc_UnicodeEncodeError)) {
         if (PyUnicodeEncodeError_GetEnd(exc, &end))
             return NULL;
     }
-    else if (PyObject_IsInstance(exc, PyExc_UnicodeDecodeError)) {
+    else if (PyObject_TypeCheck(exc, (PyTypeObject *)PyExc_UnicodeDecodeError)) {
         if (PyUnicodeDecodeError_GetEnd(exc, &end))
             return NULL;
     }
-    else if (PyObject_IsInstance(exc, PyExc_UnicodeTranslateError)) {
+    else if (PyObject_TypeCheck(exc, (PyTypeObject *)PyExc_UnicodeTranslateError)) {
         if (PyUnicodeTranslateError_GetEnd(exc, &end))
             return NULL;
     }
@@ -712,7 +704,7 @@ PyObject *PyCodec_ReplaceErrors(PyObject *exc)
 {
     Py_ssize_t start, end, i, len;
 
-    if (PyObject_IsInstance(exc, PyExc_UnicodeEncodeError)) {
+    if (PyObject_TypeCheck(exc, (PyTypeObject *)PyExc_UnicodeEncodeError)) {
         PyObject *res;
         int kind;
         void *data;
@@ -731,14 +723,14 @@ PyObject *PyCodec_ReplaceErrors(PyObject *exc)
         assert(_PyUnicode_CheckConsistency(res, 1));
         return Py_BuildValue("(Nn)", res, end);
     }
-    else if (PyObject_IsInstance(exc, PyExc_UnicodeDecodeError)) {
+    else if (PyObject_TypeCheck(exc, (PyTypeObject *)PyExc_UnicodeDecodeError)) {
         if (PyUnicodeDecodeError_GetEnd(exc, &end))
             return NULL;
         return Py_BuildValue("(Cn)",
                              (int)Py_UNICODE_REPLACEMENT_CHARACTER,
                              end);
     }
-    else if (PyObject_IsInstance(exc, PyExc_UnicodeTranslateError)) {
+    else if (PyObject_TypeCheck(exc, (PyTypeObject *)PyExc_UnicodeTranslateError)) {
         PyObject *res;
         int kind;
         void *data;
@@ -765,7 +757,7 @@ PyObject *PyCodec_ReplaceErrors(PyObject *exc)
 
 PyObject *PyCodec_XMLCharRefReplaceErrors(PyObject *exc)
 {
-    if (PyObject_IsInstance(exc, PyExc_UnicodeEncodeError)) {
+    if (PyObject_TypeCheck(exc, (PyTypeObject *)PyExc_UnicodeEncodeError)) {
         PyObject *restuple;
         PyObject *object;
         Py_ssize_t i;
@@ -863,7 +855,7 @@ PyObject *PyCodec_XMLCharRefReplaceErrors(PyObject *exc)
 
 PyObject *PyCodec_BackslashReplaceErrors(PyObject *exc)
 {
-    if (PyObject_IsInstance(exc, PyExc_UnicodeEncodeError)) {
+    if (PyObject_TypeCheck(exc, (PyTypeObject *)PyExc_UnicodeEncodeError)) {
         PyObject *restuple;
         PyObject *object;
         Py_ssize_t i;
@@ -1007,7 +999,8 @@ PyCodec_SurrogatePassErrors(PyObject *exc)
     Py_ssize_t start;
     Py_ssize_t end;
     PyObject *res;
-    if (PyObject_IsInstance(exc, PyExc_UnicodeEncodeError)) {
+
+    if (PyObject_TypeCheck(exc, (PyTypeObject *)PyExc_UnicodeEncodeError)) {
         unsigned char *outp;
         if (PyUnicodeEncodeError_GetStart(exc, &start))
             return NULL;
@@ -1078,7 +1071,7 @@ PyCodec_SurrogatePassErrors(PyObject *exc)
         Py_DECREF(object);
         return restuple;
     }
-    else if (PyObject_IsInstance(exc, PyExc_UnicodeDecodeError)) {
+    else if (PyObject_TypeCheck(exc, (PyTypeObject *)PyExc_UnicodeDecodeError)) {
         unsigned char *p;
         Py_UCS4 ch = 0;
         if (PyUnicodeDecodeError_GetStart(exc, &start))
@@ -1157,7 +1150,8 @@ PyCodec_SurrogateEscapeErrors(PyObject *exc)
     Py_ssize_t start;
     Py_ssize_t end;
     PyObject *res;
-    if (PyObject_IsInstance(exc, PyExc_UnicodeEncodeError)) {
+
+    if (PyObject_TypeCheck(exc, (PyTypeObject *)PyExc_UnicodeEncodeError)) {
         char *outp;
         if (PyUnicodeEncodeError_GetStart(exc, &start))
             return NULL;
@@ -1188,7 +1182,7 @@ PyCodec_SurrogateEscapeErrors(PyObject *exc)
         Py_DECREF(object);
         return restuple;
     }
-    else if (PyObject_IsInstance(exc, PyExc_UnicodeDecodeError)) {
+    else if (PyObject_TypeCheck(exc, (PyTypeObject *)PyExc_UnicodeDecodeError)) {
         PyObject *str;
         unsigned char *p;
         Py_UCS2 ch[4]; /* decode up to 4 bad bytes. */