Re: qt error trapping

[<pl...@pi...>]

On 30/11/15 08:30, Daniel J Sebald wrote:
> 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
>

Just to clarify my original error , I was su into a  normal user account 
. Gnuplot works correctly for that user account when logged in directly. 
  Whatever happened before, both qt and wxt are functional in the same 
context now.

I switch user with :  su -  username

I think the error is reproduced by $DISPLAY being undefined.  This is a 
new installation where I have been doing some configuration changes so 
it may well have been that for some reason the user account was not 
properly configured when I initially hit this problem.

I think your 'root without i ' test is also creating a context where 
$DISPLAY is undefined.

Having determined that, it still comes back to some poor error trapping 
that maybe ought to be reviewed.


The libGL errors I'm now getting from qt are a bit odd because both drm 
and nouveau are loaded already. The nouveau driver has been default on 
Fedora for quite a while, it is not really that 'experimental' any more.

modprobe nouveau returns zero ( no error ) so it's odd , firstly that 
something is trying load it at this stage ( Xwindow server running ) and 
secondly that it somehow reports an error when trying.


Again this may be an invitation to check over the error trapping.

Thanks for taking an interest.

Peter.