Prevent ioctl op codes from being sign extended from int to unsigned long

when used on platforms that actually define ioctl as taking an unsigned long.
(the BSDs and OS X / Darwin)

Adds a unittest for fcntl.ioctl that tests what happens with both positive and
negative numbers.

This was done because of issue1471 but I'm not able to reproduce -that- problem
in the first place on Linux 32bit or 64bit or OS X 10.4 & 10.5 32bit or 64 bit.

1 files changed, 2 insertions, 0 deletions

diff --git a/Doc/library/fcntl.rst b/Doc/library/fcntl.rst
index 5050a7f..b3b977f 100644
--- a/Doc/library/fcntl.rst
+++ b/Doc/library/fcntl.rst
@@ -50,6 +50,8 @@ The module defines the following functions:
    operations are typically defined in the library module :mod:`termios` and the
    argument handling is even more complicated.
 
+   The op parameter is limited to values that can fit in 32-bits.
+
    The parameter *arg* can be one of an integer, absent (treated identically to the
    integer ``0``), an object supporting the read-only buffer interface (most likely
    a plain Python string) or an object supporting the read-write buffer interface.