Add Cred::ssh_key_from_memory

[fooker]

Solves https://github.com/alexcrichton/git2-rs/issues/320.

[alexcrichton]

Thanks! Should the keys though be &[u8] instead of &str?

[fooker]

Not really. They are in the same text format as stored in the file. It's mostly human readable.

[alexcrichton]

Ok great! Could a test be added to ensure that's the case as well?

[agrinman]

@fooker I tried using this but get Error { code: -1, klass: -1, message: "this version of libgit2 was not built with ssh memory credentials.; class=Invalid (3)" }. Looks like libgit2 compilation flags needs to change as well? Not sure how to do this but can look into it.

[fooker]

@alexcrichton can you give me some hints how to implement such a test? I think this would involve some integration testing requiring a existing server to test against.

@agrinman I've seen the error message in several issues before. I don't have that problem on my systems. Looks like this is something platform dependent.

[fooker]

@agrinman look like HAVE_LIBSSH2_MEMORY_CREDENTIALS must be set while building libssh, which is an external library AFAIK.

[alexcrichton]

@fooker oh I'm just thinking of calling this method and asserting it returns a success, no need to conned to a server, basically just feed it a generated SSH certificate

[alexcrichton]

Thanks!