bpo-33767: Fix improper use of SystemError by mmap.mmap objects (GH-7381)

Raise TypeError instead of SystemError for unsupported operations. (cherry picked from commit e9e3976) Co-authored-by: Zackery Spytz <zspytz@gmail.com>

Author: miss-islington

Lib/test/test_mmap.py

@@ -734,6 +734,13 @@ def test_resize_past_pos(self):
  self.assertRaises(ValueError, m.write_byte, 42)
  self.assertRaises(ValueError, m.write, b'abc')
 
+ def test_concat_repeat_exception(self):
+ m = mmap.mmap(-1, 16)
+ with self.assertRaises(TypeError):
+ m + m
+ with self.assertRaises(TypeError):
+ m * 2
+
 
 class LargeMmapTests(unittest.TestCase):
 

Misc/NEWS.d/next/Library/2018-06-03-22-41-59.bpo-33767.2e82g3.rst

@@ -0,0 +1,3 @@
+The concatenation (``+``) and repetition (``*``) sequence operations now
+raise :exc:`TypeError` instead of :exc:`SystemError` when performed on
+:class:`mmap.mmap` objects. Patch by Zackery Spytz.

Modules/mmapmodule.c

@@ -812,24 +812,6 @@ mmap_subscript(mmap_object *self, PyObject *item)
  }
 }
 
-static PyObject *
-mmap_concat(mmap_object *self, PyObject *bb)
-{
- CHECK_VALID(NULL);
- PyErr_SetString(PyExc_SystemError,
- "mmaps don't support concatenation");
- return NULL;
-}
-
-static PyObject *
-mmap_repeat(mmap_object *self, Py_ssize_t n)
-{
- CHECK_VALID(NULL);
- PyErr_SetString(PyExc_SystemError,
- "mmaps don't support repeat operation");
- return NULL;
-}
-
 static int
 mmap_ass_item(mmap_object *self, Py_ssize_t i, PyObject *v)
 {
@@ -949,8 +931,8 @@ mmap_ass_subscript(mmap_object *self, PyObject *item, PyObject *value)
 
 static PySequenceMethods mmap_as_sequence = {
  (lenfunc)mmap_length, /*sq_length*/
- (binaryfunc)mmap_concat, /*sq_concat*/
- (ssizeargfunc)mmap_repeat, /*sq_repeat*/
+ 0,  /*sq_concat*/
+ 0,  /*sq_repeat*/
  (ssizeargfunc)mmap_item, /*sq_item*/
  0, /*sq_slice*/
  (ssizeobjargproc)mmap_ass_item, /*sq_ass_item*/