In a remoteSSH LiveShare read/write terminal, terminal control applications are blacked out for the guest

[sjdv1982]

Describe what happened:

1. The host opened an SSH remote VSCode session via Remote Explorer.

2. The remote session was LiveShared with a guest.

3. A terminal was opened and shared in read/write mode.

4. A terminal control applications vi, ipython and jupyter console were opened in the shared terminal. In each case:

• For the guest, the application terminal was black. For a a few milliseconds after a key press, it would display correctly, then black out again.
• It didn't matter whether the host or guest launched the terminal control application.
• The application always displayed correctly for the host.
• For read-only terminals, the application displayed correctly for both host and guest

What was your system configuration? Product and Version [VS/VSCode]: VSCode. Host and guest are both running: Version: 1.44.2 Commit: ff915844119ce9485abfe8aa9076ec76b5300ddd Date: 2020-04-16T17:50:03.709Z Electron: 7.1.11 Chrome: 78.0.3904.130 Node.js: 12.8.1 V8: 7.8.279.23-electron.0 OS: Linux x64 4.15.0-96-generic OS Version[macOS/Windows]: Host, remote and guest are both running Kubuntu 18.04.3 LTS Live Share Extension Version: 1.0.2048 Target Platform or Language [e.g. Node.js]: n/a

Steps to Reproduce / Scenario: See above.

Please attach logs to this issue: You can access them via the Live Share: Export Logs command from the command palette (ctrl + shift + p) and attach them to this issue

log.zip Log

[jramsay]

@sjdv1982: thanks for filing this issue!

Assigning to @IlyaBiryukov for further investigation

[IlyaBiryukov]

It must be because of some ANSI-sequences that a guest terminal renderer sends to the terminal process. For read-only terminals we ignore all input from the guests. If we ignore all ANSI-sequences from the guest terminals, this should fix it, and still let guest users participate in the terminals.

I'll have time to get to this issue in a several weeks or later.

[sjdv1982]

@IlyaBiryukov Thank you for looking into it. LiveShare has been great for us already, but shared IPython consoles would be ideal for remote collaboration. We are really looking forward to this fix!

[sjdv1982]

I tried again, and the problem is gone! Did you do something on the LiveShare server side?

[IlyaBiryukov]

It may have been an issue in the renderer in VSCode, and a recent update may have fixed it. We don't do anything with the traffic between collaboration session participants. In fact, we cannot even read it on the server side because it's encrypted end-to-end on the client side with ssh connection.

[sjdv1982]

No recent update for me, it is still 1.44.2, same commit. I hope this isn't a heisenbug?

[github-actions[bot]]

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