In trying to use the mmap offset to allow me to work with a 12GB file, I
encountered the fact that the new offset parameter was a ssize_t, which
is only 32 bits on my platform (OS X). The mmap offset in C is defined
to be an off_t
(http://opengroup.org/onlinepubs/007908775/xsh/mmap.html), which is 64
bits on my platform. The attached patch attempts to fix the non-Windows
code to have an off_t offset parameter and allows my code to access all
12 GB of my file. As a warning, this is the first time I've even looked
at the Python source, and wouldn't even consider myself a Python coder;
I just use Python every few months. Review the patch carefully.