[issue4681] mmap offset should be off_t instead of ssize_t, and size calculation needs corrected

[Nadeem Vawda]

Changes by Nadeem Vawda <nadeem.vawda at gmail.com>:


----------
nosy: +nvawda

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue4681>
_______________________________________