On Sat, Feb 24, 2024 at 07:36:21AM +0100, Patrick Steinhardt wrote: > Thanks for your report! > > This has to be because we now initialize the refdb at a later point. The > problem here was that before my change, we initialized the refdb at a > point when it wasn't clear what the remote actually used as the object > format. The consequence was twofold: > > - Cloning a repository with bundles was broken in case the remote uses > the SHA256 object format. > > - Cloning into a repository that uses reftables when the remote uses > the SHA256 object format was broken, too. > > Both of these have the same root cause: because we didn't connect to the > remote yet we had no idea what object format the remote uses. And as we > initialized the refdb early, it was then initialized with the default > object format, which is SHA1. > > The change was to move initialization of the refdb to a later point in > time where we know what object format the remote uses. By necessity, > this has to be _after_ we have connected to the remote, because there is > no way to learn about it without connecting to it. > > One consequence of initializing the refdb at a later point in time is > that we have no "HEAD" yet, and a repo without the "HEAD" file is not > considered to be a repo. Thus, git-config(1) would now rightfully fail. > > I assume that you discovered it via a remote helper that does something > more interesting than git-config(1). Indeed, my own usecase is a remote helper that uses libgit.a and uses is_git_directory indirectly, but I could imagine other remote helpers that could be using other git commands that rely on is_git_directory returning true. > I have to wonder whether we ever > really specified what the environment of a remote helper should look > like when used during cloning. Conceptually it doesn't feel _wrong_ to > have a not-yet-initialized repo during clone. How about this: it should look like what you'd get from `git init $repo`. > But on the other hand, regressing functionality like this is of course > bad. I was wondering whether we can get around this issue by setting > e.g. GIT_DIR explicitly when spawning the remote helper, but I don't > think it's as easy as that. GIT_DIR is already set when spawning the remote helper. My remote helper is using setup_git_directory_gently and uses the value of nongit_ok for the cases where the executable is used without being wrapped by git (it provides extra commands), I guess I could use whether GIT_DIR is set as a workaround. > Another idea would be to simply pre-create HEAD regardless of the ref > format, pointing to an invalid ref "refs/heads/.invalid". This is the > same trick we use for the reftable backend, and should likely address > your issue. The interesting thing is that `git init $repo` does give you an invalid HEAD (and that's what would happen during git clone too), with either ``` ref: refs/heads/master ``` or ``` ref: refs/heads/main ``` depending on configuration. Mike
