Re: [PATCH] Preserve cwd in setup_git_directory()

From: Nguyen Thai Ngoc Duy <pclouds@gmail.com>
Date: Jul 24, 2008, 18:37 UTC
Message-ID: <fcaeb9bf0807241137h65292d7egad8cc5f797114607@mail.gmail.com>
In-Reply-To: <alpine.DEB.1.00.0807241506340.8986@racer>

On 7/24/08, Johannes Schindelin <Johannes.Schindelin@gmx.de> wrote:

Show 33 quoted lines

> Hi,
>
>  On Thu, 24 Jul 2008, Nguyen Thai Ngoc Duy wrote:
>
>  > On 7/24/08, Johannes Schindelin <Johannes.Schindelin@gmx.de> wrote:
>  >
>
> > >  On Thu, 24 Jul 2008, Nguyen Thai Ngoc Duy wrote:
>  > >
>  > >  > When GIT_DIR is not set, cwd is used to determine where .git is. If
>  > >  > core.worktree is set, setup_git_directory() needs to jump back to
>  > >  > the original cwd in order to calculate worktree, this leads to
>  > >  > incorrect .git location later in setup_work_tree().
>  > >
>  > > I do not understand.  core.worktree is either absolute, in which case
>  > > there is no problem.  Or it is relative to where the config lives, no?
>  >
>  > The problem is GIT_DIR is not absolute in this case. So cwd must stay
>  > where git dir is until it is absolute-ized by setup_work_tree().
>
>
> I do not see GIT_DIR being set in your test case at all.
>
>  I do not see how get_git_work_tree() ro get_relative_cwd() should ever be
>  allowed to chdir().
>
>  _If_ they were (which I strongly doubt), they should chdir() back
>  themselves.
>
>  I now wasted easily 30 minutes just trying to make sense of your patch and
>  your response.  And I am still puzzled.
>
>  Your commit message was of no help.

Alright, let's look at the code.

 1. cwd is moved to toplevel working directory by setup_git_directory_gently()
 2. setup_git_env() by default will set git_dir variable as ".git" as
part of check_repository_format_gently()
 3. now in setup_git_directory() finds out core.worktree, it chdir()
to get relative prefix
 4. setup_work_tree() sees that git_dir is not absolute path, it makes
git_dir absolute

If in step 3, it does not chdir(), step 4 will be right. In this case, step 3 does chdir() and not going back, access to git repository will fail as Geoff Russell discovered.

-- 
Duy