Re: qt error trapping

[Daniel J S. <dan...@ie...>]

On 11/30/2015 02:09 AM, pl...@pi... wrote:
> On 30/11/15 04:01, Daniel J Sebald wrote:
>> On 11/29/2015 03:38 PM, pl...@pi... wrote:
>>> Hi,
>>>
>>> I just ran current cvs gnuplot while su as another user. This meant that
>>> gnuplot could not find the DISPLAY to connect to. However this failure
>>> was not correctly ( at all ) trapped and I needed to ^C out to get back
>>> to the gnupplot prompt.
>>>
>>> I would expect it to drop out instantly , preferably with an error
>>> message.
>>>
>>>
>>> gnuplot> plot [-pi:pi] sin(x)
>>> QXcbConnection: Could not connect to display
>>> q
>>>
>>> quit
>>> ^C
>>> gnuplot>
>>>
>>>
>>> Presumably there are other reasons qt may fail to open the plot window
>>> and this rather unusual situation probably highlights poor error
>>> trapping here.
>>>
>>> Regards, Peter.
>>
>> Please create a bug report on the bug tracker with this message if you
>> haven't done so already. The Qt terminal is pretty good, but I'm sure
>> there are some things not done just right. Be sure to repeat what you
>> are doing with something like the WXT terminal which also uses the
>> graphics framework, and check if that hangs as well. Thanks.
>>
>> If you want to run under the root, there is "su -l" option.
>>
>> Dan
>>
>
> Thanks Dan,
>
> I tired wxt and threw a seg. fault . However, after rebooting both
> terminals seem to act correctly. There may have been some libraries
> still in memory from before a routine update. I probably had not power
> cycled the machine for about a week and there had been updates.
>
> I just tried to repeat this to get more detail and it seems to be
> trapped correctly:
>
>
> gnuplot> plot [-pi:pi] sin(x)
> libGL error: failed to open drm device: Permission denied
> libGL error: failed to load driver: nouveau
> gnuplot>
>
>
> Unless I see something similar again, I would conclude it was a one-off
> error, probably due to mixed library modules lurking in memory.
>
> Sorry for the noise.
>
> Peter.

I don't know what to conclude from that.  The first error

>>> QXcbConnection: Could not connect to display

looks like something that would happen if the gnome (or similar) 
framework is not initialized, as the root has by default.  On the other 
hand, the second case looks like libGL errors.  Nouveau is an 
experimental libGL driver intended for Nvidia cards.

I think I'm able to replicate what you originally saw, just by running 
from root without the -l option.  The error I get is:

Terminal type set to 'qt'
gnuplot> plot x
**
GLib-GIO:ERROR:gdbusconnection.c:2270:initable_init: assertion failed: 
(connection->initialization_error == NULL)

exit
^C
gnuplot> exit

Dan