[PATCH] ccan: Fix calling memset with zero length parameter.

[Andreas Schneider]

On Thursday 11 July 2013 13:47:46 Volker Lendecke wrote:
> On Thu, Jul 11, 2013 at 01:36:54PM +0200, Andreas Schneider wrote:
> > Signed-off-by: Andreas Schneider <asn at samba.org>
> > ---
> > 
> >  lib/ccan/tally/tally.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/lib/ccan/tally/tally.c b/lib/ccan/tally/tally.c
> > index 774373c..395c17c 100644
> > --- a/lib/ccan/tally/tally.c
> > +++ b/lib/ccan/tally/tally.c
> > @@ -510,7 +510,9 @@ char *tally_histogram(const struct tally *tally,
> > 
> >  			count = 0;
> >  		
> >  		}
> > 
> > -		memset(p, '*', count);
> > +		if (count > 0) {
> > +			memset(p, '*', count);
> > +		}
> > 
> >  		p += count;
> >  		*p = '\n';
> >  		p++;
> 
> Hmmm. That's not allowed?
> 
> Volker

VERIFY	 	Build Log	 	the build on i686 reports a broken memset() call at 
line 2385 of the build log:

  2381                   from ../lib/ccan/likely/likely.h:5,
  2382                   from ../lib/ccan/tally/tally.c:4:
  2383  In function 'memset',
  2384      inlined from 'tally_histogram' at ../lib/ccan/tally/tally.c:513:9:
  2385  /usr/include/bits/string3.h:81:30: warning: call to 
'__warn_memset_zero_len' declared with attribute warning: memset used with 
constant zero length parameter; this could be due to transposed parameters 
[enabled by default]
  2386         __warn_memset_zero_len ();
  2387                                ^

I didn't see how could could be always 0 here but probably count = 0 is what 
the compiler sees and warns about.


	-- andreas

-- 
Andreas Schneider                   GPG-ID: F33E3FC6
Samba Team                             asn at samba.org
www.samba.org