Support ssh-agent and external sign binaries for commit signing with ssh

[chirpcel]

This Pull Request fixes/closes #2188.

It changes the following:

• Respect configuration for alternative signing binary (for example 1Password ssh agent)
• Using ssh-keygen for ssh signing operation to support ssh-agent
  • additional: sharing same implementation for default & configured binary

I followed the checklist:

• [x] I added unittests
• [x] I ran make check without errors
• [x] I tested the overall application
• [x] I added an appropriate item to the changelog

[chirpcel]

There's one drawback. Like before, we don't support encrypted private keys which are not loaded to agent. The error message isn't as clear as before, but from a functionality point of view it isn't different. I would make a new issue for this behavior and take a look into supporting encrypted private keys.

[extrawurst]

The error message isn't as clear as before

cant we make it as clear as before and then followup

supporting encrypted private keys.

[chirpcel]

Actually I didn't figured out how to capture the passphrase prompt, as it's spawned directly on the tty. But I just have an Idea, maybe we could provide an empty passphrase as arg to skip the password prompt and map the "wrong passphrase" error to the previous error message. I'll take a look at it today.

[chirpcel]

@extrawurst Worked, we now have a meaningful error message. I tested with 1Password SSH-Agent, Default SSH-Agent, non encrypted keys on disk and encrypted keys on disk.

[DaRacci]

Any movement on this?

This would allow me to use gitui without needing to fallback to shell to actually commit.

[chirpcel]

@DaRacci Think maintainer is currently busy as asking for co-maintainers and migrating his repo to an org for better support by more people. For now you can compile yourself with applied pr as I do or wait.

[chirpcel]

Thanks @naseschwarz for your cr! I commited your suggestions and commented on questions. I'll take a look at the remaining annotations of edge cases/optimizations. I'll update the pr soon.

I've tested the implementation on linux and macOS. Windows currently missing, maybe I can test it in a VM. Currently don't know about license/activation. Keep you updated.

[hazzuk]

Would simply like to add that I've been been running a compiled version of gitui with this pull request since August. So far I've had no issues on my Linux setup.

For me, ssh-agent support was critical, so I'd also like to say thank you for this work. I hope we see this merged one day.

[chirpcel]

@hazzuk Me too and I totally forgot that I have this PR open :face_in_clouds:
You just bring back my attention to it. I'll sort out the last open notes and the we should get it merged.

[chirpcel]

Open notes should now been solved. I'll test tomorrow on some machines with different configs and then request an follow-up review.

[chirpcel]

I didn't encounter problems on my machines. Tested on linux with openssh agent and pgp based ssh agent.

[asgeirn]

Tested on MacOS using 1Password signing, worked perfectly!

[chirpcel]

@extrawurst As this initial PR is some months old and it happened much since them, who is currently able to do a review on changes?

[cruessler]

I’ll have a look!

[cruessler]

(Just wanted to let you know that I haven’t forgotten this PR. I hope to be getting to it over the weekend.)