I'm working on a project where I'm using libgit2 and I need to support mutual TLS auth. So validating the server certificate (which I have figured out) but also passing a TLS cert for the user to the server for authentication (which I have not figured out).

This works from the git command line with the following options:

http.sslCAInfo = <path to system cA>
http.sslKey = <path to user private key>
http.sslCert = <path to user public key>

I found the GIT_SET_SSL_CERT_LOCATIONS where I set the path for sslCAInfo (I'm setting a file, setting directory to null).
But I don't see any where to set the user public/private key. I'm hoping support for something like this is here and I just can't find the correct way to set things up.

I have messed with the certificate_check callback and see it getting called to validate the server CA (it does set 'valid=1' after I used the GIT_SET_SSL_CERT_LOCATIONS). I also added a callback for 'credentials' (which it doesn't get that far before failing).

On the http server, I see the error:
(mod_openssl.c) SSL: 1 error: 0A000C7:SSL routines::peer did not return a certificate.

So, it did connected, but I'm not sure were to have the cert sent.

For reference I'm using RHEL9 provided libgit2 (from rpm) which is version 1.7.2.