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

[David Young <dyoung%pobox.com@localhost>]

On Sun, Mar 19, 2006 at 02:29:26PM +0100, Manuel Bouyer wrote:
> On Sun, Mar 19, 2006 at 12:58:35PM +0000, Ben Harris wrote:
> > In article <441D4EFD.1010507%omicron-persei-8.net@localhost> you write:
> > >YAMAMOTO Takashi wrote:
> > >>what i don't understand here is, why you think NULL initialization is
> > >>better wrt future bugs.
> > >>  
> > >>
> > >Would a dereference of the NULL ptr not cause immediate failure?
> > 
> > Not necessarily.  On older ARM systems, the kernel has a page mapped at 
> > address zero containing the CPU vectors.  Reading through null pointers 
> > works fine, and writing corrupts the vector table, which you'll only 
> > find out about when you next take a page fault, interrupt or whatever.
> 
> 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 ...

Lots will break.  Both sys/net/ and sys/netinet/ are littered with
'ptr = 0'.

Dave

-- 
David Young             OJC Technologies
dyoung%ojctech.com@localhost      Urbana, IL * (217) 278-3933