zellij 0.12 does not respond to input

[cswinter]

I just upgraded to zellij 0.12 and zellij sessions are completely unresponsive to input. None of the commands work, nor do other keys have observable effects. I've tried all of Powershell, Windows Terminal, and WSL Terminal and run zellij both under WSL and in an ssh session on an Ubuntu machine. Downgrading to 0.11 fixes the issue.

OS version:

Linux Nexus 5.4.0-73-generic #82-Ubuntu SMP Wed Apr 14 17:39:42 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

zellij version:

zellij 0.12.0

[imsnif]

Hey @cswinter, sorry for the experience. v0.12 moved to a multi-process model to support session detaching and my guess is that this is somehow related. Since I can't reproduce this issue, would you be willing to do some back-and-forth to help debug this? This would involve me attaching a version of zellij with some debug instructions, asking you to run it, press some keys and then attach a log file it will create.

[kunalmohan]

The problem seems to be with termbg. It's readme says it doesn't support Windows Terminal. But I wasn't sure about whether it works on WSL terminal, so I tried using it and it failed to get the terminal background colours. Moreover, it holds onto the stdin and so zellij can't lock onto stdin and hence doesn't respond.

[imsnif]

Dammit! Good find @kunalmohan !! I take it you're reproducing this issue too?

[kunalmohan]

I couldn't reproduce this on my ubuntu system. But I have windows as well (I barely use it), so I tried running zellij on WSL, and was able to reproduce it there.

[imsnif]

Right... do you think there's a way we can identify windows terminal and not run termbg somehow?

[kunalmohan]

I think we can try reading the environment variable "WT_SESSION". It should return Ok() on windows terminal only.
That's how termbg does it
https://github.com/dalance/termbg/blob/4957dcd7d7492ac130fb9cecf10a0e82d45f394b/src/lib.rs#L95

Edit: I'll try and test it on my system, and update here.

[imsnif]

Much appreciated, @kunalmohan !

[ephemeralriggs]

This is not limited to Windows. I observe the same on FreeBSD.

(Edit: Let me know how I can help debugging this)

[imsnif]

Thanks @riggs- !
Sounds to me like we might want to ditch termbg for now while we sort this out.
@kunalmohan - do you agree? I just want to make sure that if we remove termbg completely the issue is gone. If so I'll issue a hotfix to main and ask all people involved in the thread to test it before I release a patch.

[imsnif]

Also maybe open an issue in termbg. I would guess this loop never ends even after the timeout is reached: https://github.com/dalance/termbg/blob/c451055cdba21219d0cd7d5023fd9603b554124e/src/lib.rs#L211

[kunalmohan]

@imsnif sounds good to me. I just created an issue there: dalance/termbg#5.

[imsnif]

Right, I pushed a hotfix to main. @kunalmohan, @riggs- (and @cswinter if you're around) - could you check to make sure it fixes the issue for you?

[kunalmohan]

@imsnif works for me.

[dalance]

@imsnif I tried to fix termbg. Could you try dalance/termbg@fed9852 ?

[dalance]

@imsnif I released termbg v0.3.0 to fix this issue.

[imsnif]

@dalance - thanks for the quick fix as always :)

Tbh I'm getting a little concerned about encapsulating stdin behind a dependency like this. Do you think it would be possible to get an API that would allow us to do the stdin part ourselves?
Something (roughly) like this:

thread::spawn({
    // wait for stdin and get response ourselves
    termbg::interpret_colors(response_from_stdin);
});

termbg::send_osc();

For the time being to fix this issue, I'm going to release the current patch.

[dalance]

I can provide such API. But I think there are some problems.

• How the user of API judges the end of response_from_stdin. ( termbg checks terminator character by byte )
• termbg supports not only Xterm query but also Windows API. The new API may be inconsistent with Windows API.

I'll consider the API design.

[imsnif]

Fair points. We already handle similar issues with OSC terminators elsewhere, so at least for us this is just a matter of re-using that code.

[imsnif]

@cswinter @riggs- @kebot - this has been fixed in 0.12.1 - apologies for the inconvenience. If you're still having issues, please ping me and I'll re-open and find the cause.

[ephemeralriggs]

@cswinter @riggs- @kebot - this has been fixed in 0.12.1 - apologies for the inconvenience. If you're still having issues, please ping me and I'll re-open and find the cause.

Confirmed: This solves the problem on FreeBSD. Thank you for the quick response and fix!

[cswinter]

Can also confirm this is now working, thanks for the quick fix. So long, tmux!