# HG changeset patch

# User Benjamin Peterson <benjamin@python.org>

# Date 1403579547 25200

# Node ID 8d963c7db507be561e26bbbb852e3a2be3327c3f

# Parent  8e0b7393e921fb5e05c40265f9272dec90512ef6

avoid overflow with large buffer sizes and/or offsets (closes #21831)

diff --git a/Lib/test/test_buffer.py b/Lib/test/test_buffer.py

--- a/Lib/test/test_buffer.py

+++ b/Lib/test/test_buffer.py

@@ -4,6 +4,7 @@ For now, tests just new or changed funct

 """

+import sys

 import unittest

 from test import test_support

@@ -29,6 +30,11 @@ class BufferTests(unittest.TestCase):

         m = memoryview(b) # Should not raise an exception

         self.assertEqual(m.tobytes(), s)

+    def test_large_buffer_size_and_offset(self):

+        data = bytearray('hola mundo')

+        buf = buffer(data, sys.maxsize, sys.maxsize)

+        self.assertEqual(buf[:4096], "")

+

 def test_main():

     with test_support.check_py3k_warnings(("buffer.. not supported",

diff --git a/Objects/bufferobject.c b/Objects/bufferobject.c

--- a/Objects/bufferobject.c

+++ b/Objects/bufferobject.c

@@ -88,7 +88,7 @@ get_buf(PyBufferObject *self, void **ptr

             *size = count;

         else

             *size = self->b_size;

-        if (offset + *size > count)

+        if (*size > count - offset)

             *size = count - offset;

     }

     return 1;

@@ -875,4 +875,4 @@ PyTypeObject PyBuffer_Type = {

     0,                                          /* tp_init */

     0,                                          /* tp_alloc */

     buffer_new,                                 /* tp_new */

-};

\ No newline at end of file

+};