Re: CVS commit: src/sys/ufs/lfs

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Mon, Mar 20, 2006 at 01:17:09AM +1100, Tyler Retzlaff wrote:
> >Then maybe NULL should be defined to something else than 0 on those
> >platforms ? I wonder how much things will break if we have NULL != 0
> >though ...
> >
> > 
> >
> my guess is more things would break, just think of all the code that does:
> char * ptr;
> ptr = NULL;
> .
> .
> if (ptr)
>    ...;
> 
> Of course good practice is to compare against NULL (as is documented in 
> misc/style).
> 
> I was merely presenting it as a way to catch derefs of bad pointers at a 
> more convenient time.  If I wrote code with this kind of bug I'd want it 
> to crash sooner and give me a useful backtrace rather than later and 
> possibly a misleading backtrace.
> 
> Even on ARM the early init to NULL would likely be better given it would 
> at least die on the next page fault as Ben says it would.
> 
> Anyway, at this point I guess I just shouldn't have made the change.

I agree with your point and I think the change is fine. I'm doing such
things in my code as well, precisely to catch use of uninitialized or
freed pointers (eventually under DIAGNOSTIC for time-critical code).

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--