On Mon, Jul 30, 2012 at 03:42:22PM +0000, Ed Maste wrote:
> I'm working through a handful of unit test failures in the FreeBSD port
> and the first issue I've come across is set_dscp failing - as it turns
> out FreeBSD requires an int value for the setsockopt() call, not a char.
>
> Looking at the Linux ip(7) man page I see the statement "TOS is a byte,"
> but all of the Linux code examples I've found in a quick Google search
> pass an int.
>
> I made the change below to fix the issue on FreeBSD but would like some
> advice on whether it's suitable on Linux (or if I need some separate
> #ifdef'd code).
I remember looking at the manpage when set_dscp() was introduced and
seeing the advice that TOS was a byte, and then insisting that we
actually use a char there.
Now that I look at the Linux source, I see that it actually works OK
with either one (!):
if (optlen >= sizeof(int)) {
if (get_user(val, (int __user *) optval))
return -EFAULT;
} else if (optlen >= sizeof(char)) {
unsigned char ucval;
if (get_user(ucval, (unsigned char __user *) optval))
return -EFAULT;
val = (int) ucval;
}
It's been like that as far back as 2.6.12 and probably farther, so no
historical baggage to worry about either.
IP_TOS doesn't appear to be in SUSv4, so there's no real "standard" to
rely on.
So: let's switch to using "int". If you send a patch with the
changelog updated with the above information then I'll apply it.
Thanks,
Ben.
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