self-hosting git clone support

[shazow]

Primarily for the lols, but it would be really cool to be able to do:

$ git clone ssh://chat.shazow.net

to get the source code of the current version running there.

Related tweet: https://twitter.com/shazow/status/1004078941349601281

v1 of this feature:

• Bundle a snapshot of the source code as an asset in the built binary (probably the output of git archive, or whatever format is most convenient for streaming out to clone requests)
• Setup the proper response for the git clone request. IIRC it calls it as a subsystem exec and just stream something like a tarball¹ a blob back? Would require a bit of research but the final implementation shouldn't be too bad. Worst case there are lots of pure-go git implementations that could be leveraged, but I'm not sure that would even be necessary.

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1. Edited for compliance with @tpope. ↩

[dmitshur]

In case it's helpful as a reference, here's a proof of concept git server over SSH protocol.

It uses git-upload-pack and git-receive-pack binaries (just git-upload-pack is sufficient for read access).

[shazow]

@shurcooL Ah perfect, thank you! Here's the meat of what we'd need: https://github.com/shurcooL/play/blob/master/231/sshgit/sshgit.go#L158