On 22-Jul-2021, at 18:43, Tom Cook <tom.k.cook@xxxxxxxxx> wrote: > On Wed, Jul 21, 2021 at 11:59 PM brian m. carlson > <sandals@xxxxxxxxxxxxxxxxxxxx> wrote: >> >> On 2021-07-21 at 09:17:36, Tom Cook wrote: >>> What did you do before the bug happened? (Steps to reproduce your issue) >>> >>> Add a git submodule to a git repository. >>> Overlay-mount that submodule to another place in the filesystem. >>> Attempt any git operation in the overlay-mounted path. >> >> I'm not sure about what you mean by an overlay-mount operation. Can you >> provide some specific commands that we can run at a shell that reproduce >> the issue? >> -- >> brian m. carlson (he/him or they/them) >> Toronto, Ontario, CA > > The easiest way to reproduce it is this: > > $ mkdir test > $ cd test > $ echo "gitdir: /foo/bar" > .git > $ git ls-remote https://github.com/torvalds/linux > > We happen to use overlay mounts in our build system in a way that maps > a git submodule from one place to another so that its "gitdir" is > invalid and then attempt a `git ls-remote` from that location which > unexpectedly fails. But the above reproduces the problem well enough. 'ls-remote' needs a valid git directory for the case where the URL is not explicitly supplied (to read the git config and learn the default remote). Making a special case for when an explicit URL is not given is not as straightforward as it seems, because by the time 'ls-remote' even knows about its arguments, it already takes a worktree prefix and sets up the environment, for which a valid Git repository path is required. I am not too familiar with this area, and I don't know how feasible it is to delay setting up the environment until after looking at the 'ls-remote' arguments. At a cursory glance, it looks difficult to do without large structural changes to the code. This might have been less of a problem with old-form submodules, where '.git' was an actual directory, rather than a text file pointer [1], but newer versions of Git discourage their usage. [1] https://git-scm.com/docs/gitsubmodules#_forms PS: we prefer bottom posting or inline replies :) --- Pointers for others who might be interested in looking into this: The immediate cause of this seems to be 'setup.c:setup_gitdir_gently()' [2] which calls 'setup_gitdir_gently_1()' with the 'die_on_error' argument set to true. This function then calls 'read_gitfile_gently()' with the same flag, which errors out when it runs 'is_git_directory()' [3], because the path in the gitfile is not a valid repository. [2] https://github.com/git/git/blob/eb27b338a3e71c7c4079fbac8aeae3f8fbb5c687/setup.c#L1234 [3] https://github.com/git/git/blob/eb27b338a3e71c7c4079fbac8aeae3f8fbb5c687/setup.c#L784-L799 --- Atharva Raykar ಅಥರ್ವ ರಾಯ್ಕರ್ अथर्व रायकर
