VNC server thoughts

ttcoder at ttcoder at
Mon May 15 20:46:04 CEST 2023

Thank you for your response Johannes,
> > It seems to require a one-liner patch though, otherwise it crashes with a 
> "invalid zero alloc" style message.
> > So I just went ahead and hardcoded a non-empty initial _area (setting it 
> to 320,200) on the first line of this constructor here (_area gets set to 
> the correct screen size later in the code path anyway). Seems leaving it set 
> to "capture.screensize" sets it to an empty area otherwise.
> > 
> >
> 8e40470556b/vnc_server/src/vnc_output.h#L162
> In what scenario have you encountered the zero-alloc crash? In goa? On 
> Sculpt? I've been recently made aware of the zero-screensize-issue by 
> the screenshot component but haven't seen any issue with the vnc server 
> so far.

Neither, actually I build vnc_server manually, and then integrate it into my proprietary "software suite" using my Jam scripts.
But today I've prepared a way to replicate the problem by compiling/building from my publically available repo on,
or even simply with the actual contents of the config file I provide in the ticket below.

> > Will look into adding password support etc but I'm already quite a happy 
> camper at any rate, this propels me way ahead.
> Password support would be a very welcome contribution.

Then I should probably open a ticket to coordinate/upstream my changes if I can pull that off. Won't happen for a few months yet though.

> Thanks for the feedback. I already fixed the example.o issue [1] and 
> will be looking into the zero-alloc crash once I'm able to reproduce it.
> [1]

Filed ticket #328 on genode-world. See you there when you have spare time (this issue can wait) :-)


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