Re: vnc clipboard support

[BALATON Zoltan <balaton@eik.bme.hu>]

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On Fri, 29 Jan 2021, Marc-André Lureau wrote:
> I also had recently some thoughts about how to implement clipboard sharing
> in a more general way for QEMU.
>
> I admit I like Christophe's suggestion ("it's somebody else problem"), but
> it falls short to me as I don't know of a common open-source remoting
> solution for various operating systems, and I don't see how it could
> integrate well with our UI and remote protocols. Or look at reusing some
> VirtualBox code perhaps?

I also thought about VirtualBox may worth a look at as that supports 
clipboard sharing and there's also Synergy 
[https://en.wikipedia.org/wiki/Synergy_(software)] that I don't know much 
but it's cross platform and may support clipboard sharing. It seems to 
have an open source fork called Barrier: 
https://github.com/debauchee/barrier

Regards,
BALATON Zoltan

> Some things I keep in mind:
> - the spice protocol had a number of iterations to fix some races. It would
> be great not to repeat the same mistakes, and I don't know if VNC have the
> same flaws or not.
> - the spice agent design isn't great: the system agent proxies messages to
> the active session. It would be nice if the new solution didn't have such a
> middle-man.
> - with wayland, clipboard sharing isn't really possible. Or not in a
> seamless way at least. Today it kinda works with some X11 compatibility
> extensions, but this will eventually go away or change behaviour.
> - the GNOME desktop is working on remoting using RDP, and they are
> implementing a DBus interface for it (
> https://gitlab.gnome.org/jadahl/mutter/-/commits/wip/remote-desktop-clipboard
> )
> - it's not just about clipboard. We would also want to have some kind of
> drag and drop (even if limited to files like Spice atm). We may want some
> windowing integration. We may also want to have access to some desktop
> services: apps, documents etc.. And what's not.
>
> That leads me to think that virtio-serial is not very well suited, as it
> doesn't allow various services / processes to come and go. I see vsock as a
> much better alternative. (I also wonder if it handles control flow any
> better btw)
>
> I think we shoud work on getting the free desktops our best-class support.
> To me, this means we need to speak the lingua franca, which is DBus. The
> great thing is that DBus is also equipped to handle services that come and
> go, handling discovery, introspection etc. Various services are already
> available. As mentioned earlier, that's what the GNOME desktop will offer
> for clipboard sharing. There are good chances other desktops will follow if
> that design works, as it should be easy for them to implement the same
> service. That means good reuse of existing desktop code. Speaking DBus on
> Windows, MacOS or Android isn't an issue. However, vsock support may be a
> bit tricky atm.
>
> Fwiw, DBus doesn't yet officially support vsock connections:
> https://gitlab.freedesktop.org/dbus/dbus/-/merge_requests/200. This a minor
> detail, as once you give it a fd for transport, it doesn't really care (I
> also took care of glib!1892 and Rust zbus)
>
> Oh and of course, since this is a new daemon, it would be really a shame
> not to write it in a modern language (hint! ;-).
>
> Hope that helps,
>
>