No support for ~username expansion in `PlainClone`

[janakerman]

Context

The git clone docs state that ~ expansion is valid in a clone URL:

The ssh and git protocols additionally support ~username expansion:

• ssh://[user@]host.xz[:port]/~[user]/path/to/repo.git/
• git://host.xz[:port]/~[user]/path/to/repo.git/
• [user@]host.xz:/~[user]/path/to/repo.git/

Observed

A PlainClone with the following repository URL ssh://git@localhost/~/cluster.git results in the error repository not found, even though git clone ssh://git@localhost/~/cluster.git is successful.

A PlainClone with the full path to the repo works as expected ssh://git@localhost/home/git/cluster.git. (Well, fails with reference not found but I'm sure that's something else.)

I believe this is because the following command is executed over SSH "git-upload-pack '/~/cluster.git'" when it should not have a leading /.

Details

• I'm running a local git server using Docker sudo docker run -p 22:22 -v /tmp/keys:/git-server/keys -v /tmp/repos:/git-server/repos -e REPO=cluster.git -e TAR_URL="https://github.com/stefanprodan/podinfo/archive/3.2.0.tar.gz" fluxcd/gitsrv:latest
  • The container's git user's home dir is /home/git/
  • The repository I'm attempting to close is at /home/git/cluster.git
• I've tested the above theory by exec'ing onto the git server and running git-upload-pack '~/cluster.git' works, but git-upload-pack '/~/cluster.git' does not (note leading / in the path in the latter).

This is reproducible with something like this:

	auth, err := ssh.NewPublicKeysFromFile("git", "/tmp/keys/id_rsa", "")
	if err != nil {
		panic(err)
	}

	_, err = gogit.PlainCloneContext(context.Background(), "/tmp/test", false, &gogit.CloneOptions{
		URL:           "ssh://git@localhost/~/cluster.git",
		Auth:          auth,
		RemoteName:    gogit.DefaultRemoteName,
		ReferenceName: "master",
		SingleBranch:  true,
		NoCheckout:    false,
		Progress:      nil,
		Tags:          gogit.NoTags,
	})
	if err != nil {
		panic(err)
	}

Potential solutions

I've pondered on adding some logic to plumbing/transport/ssh/common.go:endpointToCommand to detect when the first path segment is ~ and remove the leading /. I'd like to write a test for this but I haven't figured out a nice way to do that yet without polluting the current user's home directory.

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