python
diff --git a/‎Lib/test/test_mmap.py
Copy file name to clipboardExpand all lines: Lib/test/test_mmap.py
+38Lines changed: 38 additions & 0 deletions b/‎Lib/test/test_mmap.py
Copy file name to clipboardExpand all lines: Lib/test/test_mmap.py
+38Lines changed: 38 additions & 0 deletions
diff --git a/‎Modules/mmapmodule.c
Copy file name to clipboardExpand all lines: Modules/mmapmodule.c
+25-1Lines changed: 25 additions & 1 deletion b/‎Modules/mmapmodule.c
Copy file name to clipboardExpand all lines: Modules/mmapmodule.c
+25-1Lines changed: 25 additions & 1 deletion
@@ -1058,6 +1058,44 @@ def __exit__(self, exc_type, exc_value, traceback):
                 with self.assertRaisesRegex(ValueError, "mmap closed or invalid"):
                     m.write_byte(X())
 
+    @unittest.skipUnless(os.name == 'nt', 'requires Windows')
+    def test_access_violations(self):
+        PAGE_NOACCESS = 0x01
+
+        with open(TESTFN, 'bw+') as f:
+            f.write(b'\0'* PAGESIZE)
+            f.flush()
+
+            m = mmap.mmap(f.fileno(), PAGESIZE)
+            m._protect(PAGE_NOACCESS, 0, PAGESIZE)
+            with self.assertRaises(OSError):
+                m.read(PAGESIZE)
+            with self.assertRaises(OSError):
+                m.read_byte()
+            with self.assertRaises(OSError):
+                m.readline()
+            with self.assertRaises(OSError):
+                m.write(b'\0'* PAGESIZE)
+            with self.assertRaises(OSError):
+                m.write_byte(0)
+            with self.assertRaises(OSError):
+                m[0]  # test mmap_subscript
+            with self.assertRaises(OSError):
+                m[0:10]  # test mmap_subscript
+            with self.assertRaises(OSError):
+                m[0:10:2]  # test mmap_subscript
+            with self.assertRaises(OSError):
+                m[0] = 1
+            with self.assertRaises(OSError):
+                m[0:10] = b'\0'* 10
+            with self.assertRaises(OSError):
+                m[0:10:2] = b'\0'* 5
+            with self.assertRaises(OSError):
+                m.move(0, 10, 1)
+            with self.assertRaises(OSError):
+                list(m)  # test mmap_item
+
+
 class LargeMmapTests(unittest.TestCase):
 
     def setUp(self):
 
@@ -1000,6 +1000,27 @@ mmap__sizeof__method(mmap_object *self, void *Py_UNUSED(ignored))
 }
 #endif
 
+#if defined(MS_WINDOWS) && defined(Py_DEBUG)
+static PyObject *
+mmap_protect_method(mmap_object *self, PyObject *args) {
+    DWORD flNewProtect, flOldProtect;
+    Py_ssize_t start, length;
+
+    CHECK_VALID(NULL);
+
+    if (!PyArg_ParseTuple(args, "Inn:protect", &flNewProtect, &start, &length)) {
+        return NULL;
+    }
+
+    if (VirtualProtect((void *) (self->data + start), length, flNewProtect, &flOldProtect) == 0) {
+        PyErr_SetFromWindowsErr(GetLastError());
+        return NULL;
+    }
+
+    Py_RETURN_NONE;
+}
+#endif
+
 #ifdef HAVE_MADVISE
 static PyObject *
 mmap_madvise_method(mmap_object *self, PyObject *args)
@@ -1069,7 +1090,10 @@ static struct PyMethodDef mmap_object_methods[] = {
     {"__exit__",        (PyCFunction) mmap__exit__method,       METH_VARARGS},
 #ifdef MS_WINDOWS
     {"__sizeof__",      (PyCFunction) mmap__sizeof__method,     METH_NOARGS},
-#endif
+#ifdef Py_DEBUG
+    {"_protect",        (PyCFunction) mmap_protect_method,      METH_VARARGS},
+#endif // Py_DEBUG
+#endif // MS_WINDOWS
     {NULL,         NULL}       /* sentinel */
 };