Re: [Plplot-devel] gd driver and dlopen() flags

[Alan W. I. <ir...@be...>]

On Mon, 16 Sep 2002, [iso-8859-1] Jo=E3o Cardoso wrote:

>
> Hi,
>
> In the current cvs I can't use the png driver:
>
> [jcard@feup] ./x01c -dev png -o po.png -debug
> Plplot library version: 5.1.0
> plLoadDriver: Device not loaded!
> plLoadDriver: tag=3Dpng, drvidx=3D4
> plLoadDriver: Trying to load gdd_drv.so on ./drivers/gdd_drv.so
> plLoadDriver: Trying to load at
> /usr/local/lib/plplot5.1.0/data/../drivers/gdd_drv.so
> Unable to load driver: gdd_drv.so.
> Reason: /usr/local/lib/plplot5.1.0/data/../drivers/gdd_drv.so: cannot
> open shared object file: No such file or directory

This misleading error message from the wrong (second) dlerror has been
annoying me for a while so I just fixed it in CVS.  Could you please try
this again after cvs update?  That should give you both the first and secon=
d
dlerror error messages with the -debug option (and no dlerror error message=
s
if you don't specify -debug).

Once the first dlerror message is output, I suspect you will get an error
message about no access to a symbol in one of our libraries.  If so, could
you try to fix it by setting LD_LIBRARY_PATH to point to the directory
(./ in this case) where our libraries have been built?


> If I change in plcore.c, line 1855, RTLD_NOW to RTLD_LAZY, it works:
>
> [jcard@feup] ./x01c -dev png -o po.png -debug
> Plplot library version: 5.1.0
> plLoadDriver: Device not loaded!
> plLoadDriver: tag=3Dpng, drvidx=3D4
> plLoadDriver: Trying to load gdd_drv.so on ./drivers/gdd_drv.so
> Opened po.png
> Segmentation fault
>
> Oops... at home it worked (exactly same environement). Nevertheless, now
> the driver is opened and the output file created and partly filled, so
> there is some problem here.

I don't need the RTLD_LAZY (or LD_LIBRARY_PATH under Debian), but I do
confirm the second error you have just found.  Something is now wrong with
the gd device driver if you don't specify -drvopt text.  I will look into i=
t
further.

From=20the Linux dlopen man page at
http://nodevice.com/sections/ManIndex/man0254.html, I don't see how
RTLD_LAZY will fix the problem.  It will, however, delay the problem until
you actually try to use the symbols, and you may have encountered the secon=
d
error (see above) before that happened.  Once you re-run with the proper
dlerror message and RTLD_NOW, we will know more.

Alan