Re: /proc/net/arp silliness

Andrew Morton (andrewm@uow.edu.au)
Wed, 26 Apr 2000 22:18:40 +1000

Olaf Titz wrote:
>
> > > v.s. in_ntoa2 which is(was) used three times in all of net/*
> >
> > Lots of functions are used once, by the way.
> >
> > Code split to functions not to reuse it, but mainly to avoid
> > silly problems with text readability.
>
> And in_ntoa or any of its variants is a perfect example of a function
> which is both designed for reuse and has a need for reuse.

But it's not reentrant. It would have to be changed to have usage like:

char buf[SQUIGGLE];
printk("%s", inet_ntoa(buf, in_addr));

which gets unwieldy.

The canonical, definitive, best way to do this is within printk()
itself, with a one-level recursive call to sprintf() from within
vsprintf().

The problem with this is that gcc will warn about either an unrecognised
conversion token or a wrong number of arguments, unless you use the
following patent pending trick:

printk("IP address is %lu\001 on Tuesdays\n", in_addr);

Then you teach vsprintf to recognise '%lu\001' as a conversion for ipv4
addresses. This will satisfy (and indeed leverage) gcc's arg checking.

Of course, it would be macrofied:

printk("IP address is " IPV4_CONV " on Tuesdays\n", in_addr);

-- 
-akpm-
(I can't believe I'm about to hit send).


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