Re: gdk_draw_segments crash the application when called with more than 32767 segments.

["Matthias Clasen" <maclas gmx de>]

> On Mon, Feb 16, 2004 at 07:19:18PM -0500, Owen Taylor wrote:
> > On Mon, 2004-02-16 at 19:07, James Willcox wrote:
> > > On Mon, 2004-02-02 at 14:11, David Odin wrote:
> > > >   Hi,
> > > > 
> > > > As bug #122026 states, gdk_draw_segments crashes the application
> when
> > > > called with more than 32767, due to a X protocol limitation.
> > > > 
> > > > Imho, an application shouldn't have to care about this.
> > > > The report in bugzilla fixes this at gdk level.
> > > > 
> > > >   Can I commit?
> > > 
> > > Was this patch approved?  You apparently commited it today, and it
> broke
> > > the build.
> > 
> > Indeed, the patch wasn't approved yet, leaving aside issues of build
> > breakage, there is one obvious problem with the patch, and two
> > issues that needed to be researched (questions I don't know the
> > answers to offhand)
> >
>   I hadn't any positive or negative response in more than two weeks.  Now
> this bug seems to have more interest.  I admit that this isn't a good
> method, but at least, now I am more confident this will be fixed soon.
> 

A little impatient, aren't you ? Two weeks is nothing compared to the age of
some of our bugs.

> >  - The patch patches the wrong file, since it is dealing with
> >    X11-specific limitations, it should be patching X specific files
> > 
>   Well spotted. See my new patch in bugzilla. But are you really sure
> this limitation isn't there in the others gdk backend?

Each backend has to deal with its own limitations.

> >  - What's the interaction of XDrawSegments with, say, a XOR mode
> >    if the segments overlap? 
> > 
>   Do you really think this is a problem with that much segments anyway?
> Beside, apart from recoding the whole thing, I don't see how to solve
> this issue. And really, I don't think this will worth it.
> 
> By the way, the man page says: "If lines intersect, the intersecting
> pixels are drawn multiple times.", so the XOR problem looks like a
> non-issue to me;
>        
> >
> >  - What's the interaction of this with maximum request sizes? Is 
> >    32767 really the right figure here or just an approximation 
> >    that works on your system?
> > 
>   The error message I got told me this should be a 16 bits value...

Having only 16 bits to store the length is one thing (which gives you an
upper bound of
32767), but the X protocol also has a maximal request size, which can vary
from server to server. So even if the X protocol may allow an XDrawSegments
request with 32767 segments, it may be too large for the server you're talking
with.

Matthias

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