Various issues related to clipboard relaying

[ehfd]

xclip apparently works on Xorg from the client to the host, but not from the host to the client. Both directions work using Xvfb.

This is reproducible on https://github.com/selkies-project/docker-nvidia-glx-desktop (where Xorg is used) and works correctly both directions on https://github.com/selkies-project/docker-nvidia-egl-desktop.

This might be limited to https://github.com/selkies-project/docker-nvidia-glx-desktop and not on bare metal remote hosts.

Note: Works and does not work for me now randomly with an unknown reason.

[totaam]

@ehfd Xpra-org/xpra#4007 (reply in thread)
Can't explain it, but a CUDA update fixed the clipboard here. Could be the same thing?

[ehfd]

Interesting. We'll take a look.

[ehfd]

Strange. It works now with an unknown condition.
Need to identify what's happening.

[ehfd]

It does not work in most times and works seldomly. Need to find the cause.

[ehfd]

Related error message:

[18:27:40] [webrtc] Failed to read clipboard contents: InvalidCharacterError: Failed to execute 'btoa' on 'Window': The string to be encoded contains characters outside of the Latin1 range.

[12:6:23] [webrtc] Failed to read clipboard contents: NotAllowedError: Document is not focused.

[ehfd]

I'm adding this to the list of urgent issues. @danisla

[ehfd]

I feel that the core issue of this problem is that the clipboard is set multiple times to the same value repeatedly when it should be only set one time, masking the new clipboard value that is supposed to be set, and there is nothing to prevent this phenomenon. It also seems to frequently prioritize the clipboard value of the client instead of bringing the host clipboard value to the client.

Some kind of control is required to not make xclip do that.

[ehfd]

I think it's a bit better because of some unknown reason, but not too sure.

[ehfd]

Possibly related to m1k1o/neko#192?

[ehfd]

May be addressed in conjunction to #74.

[ehfd]

I think that inbound works pretty okay, but there is an evident issue with outbound, where the clipboard data doesn't come to the client in certain situations.

[ehfd]

Part of the fix for #84 ?

[ehfd]

International clipboard also fixed by #149.

[ehfd]

Please reopen if issue comes out again.

[ehfd]

xclip seems to hang in certain situations, and seems to be a common issue when piping is used.

https://stackoverflow.com/questions/44553539/python-script-using-subprocess-and-xclip-hangs-if-piped-in-bash
asweigart/pyperclip#116
https://www.reddit.com/r/linuxquestions/comments/hk72dy/xclip_in_selection_clipboard_1devstdin_hanging/?rdt=33144
https://emacs.stackexchange.com/questions/39019/xclip-hangs-shell-command

xsel is a viable alternative. Meanwhile, interventions are required to fix xclip from working erratically.

[ehfd]

Remaining issues are fixed by using xsel.

[ehfd]

xsel also has the same issues as xclip where the clipboard retrieval output hangs with sufficiently large data.

Added a three-second timeout to exit when the subprocess hangs instead of having a zombie process obstructing future clipboard retrieval for now.

[ehfd]

It seems that KasmVNC has the same issues. Might be an issue with Xvfb.