# HG changeset patch
# Parent  9498736fbd8fc06299671aa952a6b9b6b75c089a
Issue #1621: Avoid relying on overflow wrapping in ctypes array creation

diff -r 9498736fbd8f Lib/ctypes/test/test_arrays.py
--- a/Lib/ctypes/test/test_arrays.py	Sat Jul 23 07:32:14 2016 +0300
+++ b/Lib/ctypes/test/test_arrays.py	Sat Jul 23 05:08:25 2016 +0000
@@ -1,3 +1,4 @@
+import sys
 import unittest
 from ctypes import *
 
@@ -161,8 +162,6 @@
         self.assertEqual(Y()._length_, 187)
 
     def test_bad_subclass(self):
-        import sys
-
         with self.assertRaises(AttributeError):
             class T(Array):
                 pass
@@ -181,5 +180,10 @@
                 _type_ = c_int
                 _length_ = 1.87
 
+    def test_size_overflow(self):
+        half_max = (c_char * (sys.maxsize // 2 + 1))
+        with self.assertRaises(OverflowError):
+            half_max * 2
+
 if __name__ == '__main__':
     unittest.main()
diff -r 9498736fbd8f Misc/NEWS
--- a/Misc/NEWS	Sat Jul 23 07:32:14 2016 +0300
+++ b/Misc/NEWS	Sat Jul 23 05:08:25 2016 +0000
@@ -38,7 +38,8 @@
 - Issue #27567: Expose the EPOLLRDHUP and POLLRDHUP constants in the select
   module.
 
-- Issue #1621: Avoid signed int negation overflow in the "audioop" module.
+- Issue #1621: Avoid signed integer overflow in the "audioop" and "ctypes"
+  modules.
 
 - Issue #27533: Release GIL in nt._isdir
 
diff -r 9498736fbd8f Modules/_ctypes/_ctypes.c
--- a/Modules/_ctypes/_ctypes.c	Sat Jul 23 07:32:14 2016 +0300
+++ b/Modules/_ctypes/_ctypes.c	Sat Jul 23 05:08:25 2016 +0000
@@ -1385,7 +1385,7 @@
         sizeof(Py_ssize_t) * (stgdict->ndim - 1));
 
     itemsize = itemdict->size;
-    if (length * itemsize < 0) {
+    if (length > PY_SSIZE_T_MAX / itemsize) {
         PyErr_SetString(PyExc_OverflowError,
                         "array too large");
         goto error;