Re: git complains packed-refs is not a directory when used with GIT_DIR and GIT_WORK_TREE envvars.

On Tue, Mar 27, 2018 at 8:31 AM, Jeff King <peff@peff.net> wrote:

It is papering over the problem in my opinion. setup_work_tree() is involved here and when it moves cwd around, it re-init git-dir (and all other paths). Before my patch we call git_path() only when we need it and git-dir is likely already updated by setup_work_tree(). After this patch, the path is set in stone before setup_work_tree() kicks in. Once it moves cwd, relative paths all become invalid.

The way setup_work_tree() does it is just bad to me. When it calls set_git_dir() again, the assumption is the new path is exactly the same as the old one. The only difference is relative vs absolute. But this is super hard to see from set_git_dir implementation. The new struct repository design also inherits this (i.e. allowing to call set_git_dir multiple times, which really does not make sense), but this won't fly long term. When cwd moves, all cached relative paths must be adjusted, we need a better mechanism to tell everybody that, not just do it for $GIT_DIR and related paths.

I am planning to fix this. This is part of the "setup cleanup" effort to keep repository.c design less messy and hopefully unify how the main repo and submodule repo are created/set up. But frankly that may take a long while before I could submit anything substantial (I also have the "report multiple worktree's HEADs correctly and make fsck count all HEADs" task, which is not small and to me have higher priority).

So I would not mind papering over it right now (with an understanding that absolute path pays some more overhead in path walking, which was th reason we tried to avoid it in setup code). A slightly better patch is trigger this path absolutization from setup_work_tree(), near set_git_dir(). But then you face some ugliness there: how to find out all ref stores to update, or just update the main ref store alone.