Subject: Re: [PATCH] setup: set env $GIT_WORK_TREE when work tree is set, like $GIT_DIR

From: Junio C Hamano <[email-masked]>
Date: Fri, 26 Jun 2015 10:15:21 -0700

Nguyễn Thái Ngọc Duy  <[email-masked]> writes:

> Bottom line is, when $GIT_DIR is set, $GIT_WORK_TREE should be set too
> unless there's no work tree. But setting $GIT_WORK_TREE inside
> set_git_dir() may backfire. We don't know at that point if work tree is
> already configured by the caller. So set it when work tree is
> detected. It does not harm if $GIT_WORK_TREE is set while $GIT_DIR is
> not.

Hmmm, setting GIT_WORK_TREE locally without exporting it to our
subprocesses would not hurt even when we do not see GIT_DIR, so I
agree "It does not harm" is true for _us_, the process that runs
this code itself.

But I am not sure if it is true for our children (e.g. hooks,
filters etc. that is spawned by us).  With this change, they inherit
GIT_WORK_TREE and no GIT_DIR, in such a case.  If they set GIT_DIR
themselves for their own use, perhaps arranging to work in somewhere
else they know by chdir'ing there, they did not have to set
GIT_WORK_TREE=. before runing git in there, but now they do, because
we start exporting GIT_WORK_TREE to interfere what they have been
doing.

"It does not harm" is probably false for our children, I would
think.  The children can do new things to avoid the harm, though.

> Reported-by: Bjørnar Snoksrud <[email-masked]>
> Signed-off-by: Nguyễn Thái Ngọc Duy <[email-masked]>
> ---
>  environment.c      |  2 ++
>  t/t0002-gitfile.sh | 17 +++++++++++++++++
>  2 files changed, 19 insertions(+)
>
> diff --git a/environment.c b/environment.c
> index 61c685b..8f1b249 100644
> --- a/environment.c
> +++ b/environment.c
> @@ -231,6 +231,8 @@ void set_git_work_tree(const char *new_work_tree)
>  	}
>  	git_work_tree_initialized = 1;
>  	work_tree = xstrdup(real_path(new_work_tree));
> +	if (setenv(GIT_WORK_TREE_ENVIRONMENT, work_tree, 1))
> +		error("Could not set GIT_WORK_TREE to '%s'", work_tree);
>  }
>  
>  const char *get_git_work_tree(void)
> diff --git a/t/t0002-gitfile.sh b/t/t0002-gitfile.sh
> index 37e9396..9393322 100755
> --- a/t/t0002-gitfile.sh
> +++ b/t/t0002-gitfile.sh
> @@ -99,4 +99,21 @@ test_expect_success 'check rev-list' '
>  	test "$SHA" = "$(git rev-list HEAD)"
>  '
>  
> +test_expect_success 'setup_git_dir twice in subdir' '
> +	git init sgd &&
> +	(
> +		cd sgd &&
> +		git config alias.lsfi ls-files &&
> +		mv .git .realgit &&
> +		echo "gitdir: .realgit" >.git &&
> +		mkdir subdir &&
> +		cd subdir &&
> +		>foo &&
> +		git add foo &&
> +		git lsfi >actual &&
> +		echo foo >expected &&
> +		test_cmp expected actual
> +	)
> +'
> +
>  test_done