[New-bugs-announce] [issue16865] ctypes arrays >=2GB in length causes exception

Jeffrey Bush report at bugs.python.org
Fri Jan 4 22:28:18 CET 2013

New submission from Jeffrey Bush:

The environment is Windows 8 Pro 64-bit running Python 64-bit in the WinPython distribution. Python is v2.7.3 built on Apr 10 2012. I first found this with create_string_buffer however I found out that it happens with an even simpler example.

The following code throws an AttributeException: class must define a _length_ attribute, which must be a positive integer.

import ctypes
c_char * int(2*1024*1024*1024) # 2GB, also fails with long() instead of int()

However the following works

import ctypes
c_char * int(2*1024*1024*1024-1) # 1 byte less than 2GB

This is the same with the other c_ types (not limited to size of memory since c_int * int(2*1024*1024*1024-1) works and would be nearly 4 times the size of the failed c_char one).

components: ctypes
messages: 179080
nosy: coderforlife
priority: normal
severity: normal
status: open
title: ctypes arrays >=2GB in length causes exception
type: behavior
versions: Python 2.7

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