Re: A bug in git-add with GIT_DIR?

[Jeff King <peff@peff.net>]

On Thu, Dec 20, 2018 at 10:37:21AM +0200, Orgad Shaneh wrote:

> I played around with t5403-post-checkout-hook, and noticed that its
> state is not exactly what I'd expect it to be.
> 
> The test setup is:
> echo Data for commit0. >a &&
> echo Data for commit0. >b &&
> git update-index --add a &&
> git update-index --add b &&
> tree0=$(git write-tree) &&
> commit0=$(echo setup | git commit-tree $tree0) &&
> git update-ref refs/heads/master $commit0 &&
> git clone ./. clone1 &&
> git clone ./. clone2 &&
> GIT_DIR=clone2/.git git branch new2 &&
> echo Data for commit1. >clone2/b &&
> GIT_DIR=clone2/.git git add clone2/b &&
> GIT_DIR=clone2/.git git commit -m new2
> 
> Now, the line before the last one executes git add clone2/b with GIT_DIR set.

When GIT_DIR is set but not GIT_WORK_TREE, the current directory is
taken as the working tree.

So that will find clone2/b (from the current directory, which is a real
file), and add an index entry with that path "clone2/b" and the sha1 of
that content.

But when commands are run from inside "clone2", they will naturally
treat "clone2" as the working tree. And since "clone2/b" does not exist
inside there, they will say "oops, it looks like this file has been
deleted".

> I'd expect that to add b inside clone2, but instead it adds an
> inexistent clone2/clone2/b, and if I stop at this line, then the
> status shows:

Sort of. It never sees the path "clone2/clone2/b", but the path in the
index coupled with the working tree being inside clone2 means that it
would look for such a file.

> On branch master
> Your branch is up to date with 'origin/master'.
> 
> Changes to be committed:
>   (use "git reset HEAD <file>..." to unstage)
> 
>         new file:   clone2/b
> 
> Changes not staged for commit:
>   (use "git add/rm <file>..." to update what will be committed)
>   (use "git checkout -- <file>..." to discard changes in working directory)
> 
>         modified:   b
>         deleted:    clone2/b
> 
> Is this the intended behavior? It looks like that's not what the test
> meant to do anyway...

This is the expected behavior if you did "cd clone2 && git status".
Looking at the test, I don't think it quite meant to do this. It looks
like it predates "git -C", but for some reason did not want to "cd" in a
subshell.

I think it would be better written as:

  git -C clone2 add b &&
  git -C clone2 commit -m new2

or:

  (
	cd clone2 &&
	git add b &&
	git commit -m new2
  )

And ditto for all of the other uses of $GIT_DIR in that script. E.g.,
the ones that do:

  GIT_DIR=clone1/.git git checkout master

are likely writing the contents of clone1's master branch to the
_current_ directory (not the working tree in clone1).

> And if I change it to (cd clone2 && git add b), then the commits look
> reasonable, but step 6 fails.

You probably just need to update the other calls, too, so they all
match.

-Peff