bpo-16865: Support arrays >=2GB in ctypes. (GH-3006)

Author: segevfiner

Lib/ctypes/test/test_arrays.py

@@ -1,4 +1,6 @@
 import unittest
+from test.support import bigmemtest, _2G
+import sys
 from ctypes import *
 
 from ctypes.test import need_symbol
@@ -181,5 +183,10 @@ class T(Array):
                 _type_ = c_int
                 _length_ = 1.87
 
+    @unittest.skipUnless(sys.maxsize > 2**32, 'requires 64bit platform')
+    @bigmemtest(size=_2G, memuse=1, dry_run=False)
+    def test_large_array(self, size):
+        c_char * size
+
 if __name__ == '__main__':
     unittest.main()

Misc/NEWS.d/next/Library/2017-09-29-16-40-38.bpo-16865.l-f6I_.rst

@@ -0,0 +1 @@
+Support arrays >=2GiB in :mod:`ctypes`.  Patch by Segev Finer.

Modules/_ctypes/_ctypes.c

@@ -1390,8 +1390,7 @@ PyCArrayType_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
     StgDictObject *stgdict;
     StgDictObject *itemdict;
     PyObject *length_attr, *type_attr;
-    long length;
-    int overflow;
+    Py_ssize_t length;
     Py_ssize_t itemsize, itemalign;
 
     /* create the new instance (which is a class,
@@ -1413,14 +1412,15 @@ PyCArrayType_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
         Py_XDECREF(length_attr);
         goto error;
     }
-    length = PyLong_AsLongAndOverflow(length_attr, &overflow);
-    if (overflow) {
-        PyErr_SetString(PyExc_OverflowError,
-                        "The '_length_' attribute is too large");
-        Py_DECREF(length_attr);
+    length = PyLong_AsSsize_t(length_attr);
+    Py_DECREF(length_attr);
+    if (length == -1 && PyErr_Occurred()) {
+        if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
+            PyErr_SetString(PyExc_OverflowError,
+                            "The '_length_' attribute is too large");
+        }
         goto error;
     }
-    Py_DECREF(length_attr);
 
     type_attr = PyObject_GetAttrString((PyObject *)result, "_type_");
     if (!type_attr) {