Re: [gpsd-dev] wsg_separation Issue

[Gary E. Miller]

Yo Beat!

I like it.  Patch is now in git head.

On Sun, 06 May 2012 14:14:10 +0200
Beat Bolli <address@hidden> wrote:

> On 06.05.12 02:13, Gary E. Miller wrote:
> > Yo Beat!
> > 
> > On Sat, 05 May 2012 23:23:13 +0200
> > Beat Bolli <address@hidden> wrote:
> > 
> >> On 05.05.12 21:38, Gary E. Miller wrote:
> >>> On Fri, 4 May 2012 09:51:38 -0400
> >>> "Bywater, Rick (SA-1)" <address@hidden> wrote:
> >>>
> >>>> I was running Coverity on gpsd-2.39 and it complained about an
> >>>> array-bounds issue in geoid.c in the function wsg84_separation.
> > 
> >> The current code is still wrong IMO:
> >>
> >>     ilat = (int)floor((90. + lat) / 10);
> >>     ilon = (int)floor((180. + lon) / 10);
> >>
> >>     /* sanity checks to prevent segfault on bad data */
> >>     if ((ilat > 90) || (ilat < -90)) {
> >>         return 0.0;
> >>     }
> >>     if ((ilon > 180) || (ilon < -180)) {
> >>         return 0.0;
> >>     }
> >>
> >> ilat and ilon are offset so as to be >= 0, but the subsequent test
> >> checks the original degree range without offset or divisor.
> >> Checking lat and lon above the i{lat,lon} calculation should work.
> > 
> > Seems to me that keeping the sanity test on the integer, rather
> > than, the float, is the way to go.  So I think you are suggesting
> > the test should be:
> > 
> >      if ((ilat > 18) || (ilat < 0)) {
> >          return 0.0;
> >      }
> >      if ((ilon > 36) || (ilon < 0)) {
> >          return 0.0;
> >      }
> > 
> > Do I have it right?
> 
> I'd reuse the GEOID_ROW and GEOID_COL constants and merge the two ifs:
> 
>     /* sanity checks to prevent segfault on bad data */
>     if ((ilat >= GEOID_ROW) || (ilat < 0) ||
>         (ilon >= GEOID_COL) || (ilon < 0))
>         return 0.0;
> 
> But other than that, it looks fine.
> 
> Regards,
> Beat




RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
        address@hidden  Tel:+1(541)382-8588

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