ioctl
POSIX specification:
http://www.opengroup.org/onlinepubs/9699919799/functions/ioctl.html
Gnulib module: ioctl
Portability problems fixed by Gnulib:
ioctl is called
ioctlsocket, and error codes for this function are not placed in
errno, and WSAGetLastError must be used instead.
unsigned long
rather than int.
Portability problems not fixed by Gnulib:
ioctl requests are platform and hardware specific.