[Kst] Crash trace...

George Staikos staikos at kde.org
Wed Mar 16 21:04:14 CET 2005

On Wednesday 16 March 2005 14:34, Andrew Walker wrote:
> As before, create a plot in a window, set number of columns to 10, shrink
> window in horizontal direction, crash...
> On Wednesday 16 March 2005 11:33 am, George Staikos wrote:
> > Which of your testcases caused this? (Or was it a different one?)
> >
> > On Wednesday 16 March 2005 14:28, Andrew Walker wrote:
> > > Here's a trace of the crash (caused by the newly introduced assert)
> > > when the pixmap size goes to zero:
> > > [KCrash handler]
> > > #4  0xf6fe97a2 in _dl_sysinfo_int80 () from /lib/ld-linux.so.2
> > > #5  0xf5b0e955 in raise () from /lib/tls/libc.so.6
> > > #6  0xf5b10319 in abort () from /lib/tls/libc.so.6
> > > #7  0xf5b07f41 in __assert_fail () from /lib/tls/libc.so.6
> > > #8  0x080adde3 in Kst2DPlot::draw (this=0x9c9c260) at qpixmap.h:271

  Ok got it.  The problem is having more plots than there are pixels in a 
given dimension.  This can be a problem for the layout algorithm too, so 
let's prevent it.  (It's a nonsensical case anyway, so there's no issue with 
preventing it, as you already identified with the cap.)  The view widget 
should have a minimum size too.

  Now we also have the issue of resizing and moving plots manually, ie: not in 
columns.  It should be impossible to resize a plot smaller than 1x1 already.  
However the regrid code could be abused also.  A user could create 1000 plots 
and then regrid with a minimum size window.  Again, it's absurd and that 
itself should probably be guarded against.

  The problem with a null pixmap is that it implies view objects that can't be 
manipulated.  I think it's completely wrong to have this happen, ever.  I 
think a good start is:

- Set maximum number of columns (done)
- Set minimum size of kstviewwidget to at least 40x25
- Set maximum number of 2dplot children of any view object to 200

This still doesn't deal with the nested view object case, but I think it 
mostly covers us.  A kst file or dcop call that tries to create a null view 
object should trigger an error and refuse to load further.

George Staikos
KDE Developer				http://www.kde.org/
Staikos Computing Services Inc.		http://www.staikos.net/

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