Mosh: Mosh Server Suddenly Exits when Starting Fish Shell

[vy-let]

I'm experiencing an issue that appears similar to #667, but without any intentionally malicious output. To debug, I'm ssh'ing in and doing

mosh-server new -v

then, from my Mac,

MOSH_KEY=<the key> mosh-client <server ip> 60001

I get to bash inside the mosh session, everything works great. Then I go to launch fish (just fish), and the debug output instantly logs

mosh-server: terminalframebuffer.cc:500: void Terminal::Renditions::set_rendition(Terminal::color_type): Assertion `false' failed.

I have the full mosh-server output, as well as a capture of what fish prints, here. I read out the capture from less, so escape characters are expanded and visible (as ESC, ^M, and ^G). I don't have the technical understanding to debug those control sequences.

I'd really appreciate any guidance you could provide.

---

Miscellaneous Info

• Mosh-server is mosh-1.3.2-32-g6f9de49 on Arch.
• Mosh-client is mosh 1.3.2 on Mac.
• Fish on the server is version 2.6.0.
• Before each try, I deleted .config/fish and .local/share/fish to reset the shell to stock configuration.
• Terminal emulator doesn't appear to be relevant (Tested iTerm Build 3.1.beta.6, and macOS Sierra Terminal)

[keithw]

Nice catch, thanks! This is also triggered by running src/examples/termemu and then fish -- a little easier to iterate than mosh-server/mosh-client.

git bisect points to the first bad commit being 4835dcf5eed93f8dee44e5d1932c38b1cd243d41.

[keithw]

Thanks again! Please let us know if this doesn't fix it for you.

[vy-let]

Works perfectly. To my surprise, all it took was pacaur -Syy mosh-git, and that did it!

Thanks, Keith, you're the best!

[rapha8l]

Hi,

I'm experimenting the same problem on Void linux version 1.3.2

• if I mosh from 1.3.2 to 1.3.2 and start fish 3.0.2 (Void on both), it disconnects
• if I do it from OpenBSD version 1.3.2 or Debian version 1.2.6, and starts fish 3.0.2, it disconnects
• if I connect from any of mosh version to an host and run fish version 2.*, then no problem

I don't know if it's a Mosh of a Fish problem (maybe I can open it on fish repo too)

Thanks

[cgull]

@rapha8l, this is fixed in Mosh source, but not in an official release yet. If you can, build Mosh from Github source on your server, that should cure your problem.

[rapha8l]

Thanks !