Re: [Plplot-devel] Segfault problems solved (sort of) [was X20c.c]

[Andrew R. <ar...@ge...>]

Hello,

First, back to the original SEGFP errors I was getting with X20c. I have
compiled x20c WITHOUT any GD driver at all, and I still get the same SEGFP
errors, so it isn't anything new introduced in the GD driver changed. I
know it is related to the plimage command, but where in it I don't know. 

>> I only actually added about 8 new lines to the driver, so the differences
>> are minimal, and there would seem to be little to go wrong there.
>
>Hmmm.  I just tried a test with the old version of gd.c, and all the
>segfaults go away.  With the new gd.c I also overrode GD2_VERS to be 1 and
>the result was no segfaults.  However, if I left it at 2 (i.e., actually
>compile your 3 calls to gdImageSetThickness(dev->im_out, pls->width)), the
>segfaults come back. Either there is something wrong with libgd 2.0.1 or more
>likely dev->im_out or pls->width are not properly set when you make these
>calls. 

pls->width should be set from plplot, and is ok. I don't think the problem
can be there. dev->im_out could have a problem, but that will sadly go back
to GD somewhere. I think something is wrong with libgd 2.0.1 - it is listed
on the gd web site as an "unstable beta", and there is a warning in the
makefile that linking order can be significant. We knew that from the very
first incarnation of the GD driver anyway, but at least for DJGPP, the
linking order has changed AGAIN *sigh*. The last STABLE version of GD is
1.8.4. I strongly suspect the problem is in GD.

>Until you can find the answer, I have overriden GD2_VERS in the interest of
>keeping -dev png operational on CVS head.

Probably a good idea, but there is sadly little I can do, because
unfortunately (fortunately?) it works on my machine and I can't replicate
your problem :-( Wekl actually I CAN replicate it, but I can also FIX it by
changing the linking order, and making sure the maths library links AFTER
libgd.a, libpng.a, and libjpeg.a . Did you try reordering the linking ? 

One other thought. Are you 100% sure that you are linking against the 2.0.1
library and not the 1.8.? library ? You might have the headers for GD 2 but
the library for GD 1 - that would probably cause an error like this.

- Andrew