SUSv3 who for Busybox

[Vladimir Dronnikov]

>> # (cd coreutils; ../scripts/objsizes | grep who)
>
> IMHO this is only useful if you plan to compare against something.
>

Indeed! Get the result for your current code. Your starting point will
be that "something". Then try to make it less.

>> Then consider replacing excessive use of option_mask32 with a local
>> unsigned opt (which can be optimized to be register).
>>
> the mask is global and used in one subroutine.

But more than once. Global would result in accessing data segment.
Local could be cached in a register. AFAI can remember. Just try.

>> Why does es exists at all if it is useless?

Just suppose you have a subroutine whose behavior depends on flags
obtained in main(). Then instead of introducing a parameter you could
refer global flags.

Regards,
--
Vladimir