[PATCH] Avoid undefined behavior in __FD_MASK

[Ondřej Bílka]

On Fri, Apr 12, 2013 at 10:29:33AM +0200, Florian Weimer wrote:
> On 04/11/2013 10:32 PM, Roland McGrath wrote:
> >>__fd_mask
> >>should really be an unsigned type, but changing that is more risky.
> >
> >That really is the right fix (and then your change is unnecessary).
> >What risks do you imagine with the type change?
> 
> The fd_bits member used to be part of the public API in the 90s, and
> someone might point a long * variable to it.  There's also a
> comment:
> 
> /* The fd_set member is required to be an array of longs.  */
> typedef long int __fd_mask;
> 
> If someone still has the discussion to Austin group issue
> bwg2001-005 (which led to the removal of the fd_bits member), it
> might shed some light onto this.
> 
> But I'm probably overly conservative here.
> 
Besides select.h files I can find fd_mask only in
sunrpc/svc.c, how would unsigned change this.

I am ok with this patch.