feat: support custom $GIT_DIR

[zhimsel]

About

While rarely used, it's possible to set the $GIT_DIR environment variable to instruct git to use a directory other than .git.

This checks if that environment variable is set; if it is, the plugin will watch that directory. If it's not set, it'll fall back to the default .git directory.

Why?

I use a non-standard .git folder in my home directory for my dotfiles (~/.git_dotfiles). If I have $GIT_DIR set in my env to work on my dotfiles and open up nvim-tree, it'll detect that we're "in a git repo".

Prior to this change, it would produce an error that it can't watch the .git directory (since it doesn't exist). With this change, it produces no error and correctly watches the $GIT_DIR directory.

Testing

I tested this in my environment by opening up nvim and nvim-tree in various scenarios, ensuring that no errors are produced and git changes are correctly detected (or correctly absent):

• Not in a git repo and $GIT_DIR unset
• In a git repo with a .git directory and $GIT_DIR unset
• In a git repo with a non-standard git-dir and $GIT_DIR unset
• In a git repo with a non-standard git-dir and $GIT_DIR set to that directory

[alex-courtis]

We added such functionality in #2012 however that resulted in a regression and was backed out.

There's a PR open now to reintroduce that functionality #2194

This does seem a lot simpler: just using $GIT_DIR when set. In the previous PR we checked git -C /path/to/repo rev-parse --absolute-git-dir

I'm not sure how this works in test case 3; I'll test it out.

[alex-courtis]

Unfortunately there are also extra regular file system watchers created for the custom git directory.

Example with GIT_DIR=/home/alex/2263/nvt/.cgd

You can see two watchers for .cgd. The first one is the desired one, with the filtered set of files.

[2023-06-12 15:35:52] [watcher] Watcher:new '/home/alex/2263/nvt' nil
[2023-06-12 15:35:52] [watcher] Event:new '/home/alex/2263/nvt'
[2023-06-12 15:35:52] [watcher] Event:start '/home/alex/2263/nvt'
[2023-06-12 15:35:52] [git] { "git", "-C", "/home/alex/2263/nvt", "rev-parse", "--show-toplevel" }
/home/alex/2263/nvt
[2023-06-12 15:35:52] [git] { "git", "-C", "/home/alex/2263/nvt", "config", "status.showUntrackedFiles" }
[2023-06-12 15:35:52] [git] running job with timeout 400ms
[2023-06-12 15:35:52] [git] git --no-optional-locks status --porcelain=v1 -z --ignored=matching -u
 M .editorconfig
?? .cgd/HEAD
?? .cgd/config
?? .cgd/description
?? .cgd/hooks/applypatch-msg.sample
?? .cgd/hooks/commit-msg.sample
?? .cgd/hooks/fsmonitor-watchman.sample
?? .cgd/hooks/post-update.sample
?? .cgd/hooks/pre-applypatch.sample
?? .cgd/hooks/pre-commit.sample
?? .cgd/hooks/pre-merge-commit.sample
?? .cgd/hooks/pre-push.sample
?? .cgd/hooks/pre-rebase.sample
?? .cgd/hooks/pre-receive.sample
?? .cgd/hooks/prepare-commit-msg.sample
?? .cgd/hooks/push-to-checkout.sample
?? .cgd/hooks/sendemail-validate.sample
?? .cgd/hooks/update.sample
?? .cgd/index
?? .cgd/info/exclude
?? .cgd/logs/HEAD
?? .cgd/logs/refs/heads/master
?? .cgd/logs/refs/remotes/origin/HEAD
?? .cgd/objects/pack/pack-86c3790f9768d4f5a4503823707e87ab8adfaea4.idx
?? .cgd/objects/pack/pack-86c3790f9768d4f5a4503823707e87ab8adfaea4.pack
?? .cgd/objects/pack/pack-86c3790f9768d4f5a4503823707e87ab8adfaea4.rev
?? .cgd/packed-refs
?? .cgd/refs/heads/master
?? .cgd/refs/remotes/origin/HEAD
!! .cgd/refs/tags/
[2023-06-12 15:35:52] [git] done
[2023-06-12 15:35:52] [git] job success    /home/alex/2263/nvt nil
[2023-06-12 15:35:52] [watcher] git start
[2023-06-12 15:35:52] [watcher] Watcher:new '/home/alex/2263/nvt/.cgd' { "FETCH_HEAD", "HEAD", "HEAD.lock", "config", "index" }
[2023-06-12 15:35:52] [watcher] Event:new '/home/alex/2263/nvt/.cgd'
[2023-06-12 15:35:52] [watcher] Event:start '/home/alex/2263/nvt/.cgd'
[2023-06-12 15:35:52] [watcher] Watcher:new '/home/alex/2263/nvt/.cgd' nil
[2023-06-12 15:35:52] [watcher] Watcher:new '/home/alex/2263/nvt/.github' nil
[2023-06-12 15:35:52] [watcher] Event:new '/home/alex/2263/nvt/.github'
[2023-06-12 15:35:52] [watcher] Event:start '/home/alex/2263/nvt/.github'
[2023-06-12 15:35:52] [watcher] Watcher:new '/home/alex/2263/nvt/.hooks' nil
[2023-06-12 15:35:52] [watcher] Event:new '/home/alex/2263/nvt/.hooks'
[2023-06-12 15:35:52] [watcher] Event:start '/home/alex/2263/nvt/.hooks'
[2023-06-12 15:35:52] [watcher] Watcher:new '/home/alex/2263/nvt/doc' nil
[2023-06-12 15:35:52] [watcher] Event:new '/home/alex/2263/nvt/doc'
[2023-06-12 15:35:52] [watcher] Event:start '/home/alex/2263/nvt/doc'

Maybe take a look at #2194 and see if you can pull something from there.

[zhimsel]

^ rebase on latest master.

[zhimsel]

Unfortunately there are also extra regular file system watchers created for the custom git directory.
You can see two watchers for .cgd. The first one is the desired one, with the filtered set of files.

@alex-courtis you're referring to these two lines?

[2023-06-12 15:35:52] [watcher] Watcher:new '/home/alex/2263/nvt/.cgd' { "FETCH_HEAD", "HEAD", "HEAD.lock", "config", "index" }
[2023-06-12 15:35:52] [watcher] Watcher:new '/home/alex/2263/nvt/.cgd' nil

I'm guessing that second one is created just by the fact that it's a file in the current directory? I suppose we could have it ignore any files that are the value of $GIT_DIR if it's set...

[zhimsel]

@alex-courtis I modified the "is this a git dir?" function for the file ignores to account for $GIT_DIR being set, as well as accounting for possibly non-absolute $GIT_DIR values.

I tested it on my machine with various scenarios of $GIT_DIR being set and unset, being relative and absolute, and being in and out of git repos. Seems to work as expected with no duplicate watchers.

[alex-courtis]

Thanks for the updates @zhimsel

I'll get to review and test this weekend.

[alex-courtis]

I don't have permission to rebase; I'll leave that to you. There look to be no conflicts.

[alex-courtis]

This works for the following case:

:; export GIT_DIR=~/2263/cgd
:; export GIT_WORK_TREE=~/2263/nvt
:; cd ~/2263
:; mkdir nvt
:; cd nvt
:; echo bar > foo
:; git add foo
:; git commit -a -m "initial commit"

:; git rev-parse --show-toplevel
/home/alex/2263/nvt

:; git rev-parse --git-dir
/home/alex/2263/cgd

$GIT_WORK_TREE set or unset
$GIT_DIR set

My git knowledge is insufficient to test cloning an existing repo with non-standard --git-dir however it should behave in a similar manner.

• Please rebase.

[zhimsel]

Please rebase.

Done! Sidenote: I renamed the original commit to use feat: to match your reclassification of this PR.

My git knowledge is insufficient to test cloning an existing repo with non-standard --git-dir however it should behave in a similar manner.

It's as simple as just setting $GIT_DIR in your shell and cloning! Git will use that directory instead of .git. The --git-dir command argument should work as well, it just has to be set for every command against your cloned repo, including anything like shell prompts and vim plugins. You can find an example in the #Install section here.

[zhimsel]

Whoops, ignore that closure. I somehow managed to target the "close with comment" button with my keyboard.

[alex-courtis]

Many thanks for pushing this difficult one through.

[zhimsel]

No problem! Thanks for reviewing and merging.