Re: [PATCH 2/8] repository, setup: introduce the_cwd

[Elijah Newren <newren@gmail.com>]

On Sun, Nov 21, 2021 at 12:56 AM René Scharfe <l.s.r@web.de> wrote:
>
> Am 21.11.21 um 01:46 schrieb Elijah Newren via GitGitGadget:
> > From: Elijah Newren <newren@gmail.com>
> >
> > Removing the current working directory causes all subsequent git
> > commands (and likely a number of non-git commands) run from that
> > directory to get confused and fail with a message about being unable to
> > read the current working directory.  That confuses end users,
> > particularly since the command they get the error from is not the one
> > that caused the problem; the problem came from the side-effect of some
> > previous command.
> >
> > We would like to avoid removing the current working directory;
>
> A worthy goal.
>
> > towards
> > this end, introduce a new the_cwd variable that tracks the current
> > working directory.  Subsequent commits will make use of this new
> > variable.
>
> Why make it a global variable instead of getting the working directory
> in the places that try to delete directories?  (Honest question, not a
> suggestion.)

As I mentioned in my response to Junio, I need to be clearer that what
I want to protect is the current working directory as of the startup
of the git process, as a proxy for the current working directory of
the parent process, so that subsequent commands started from the
parent process don't get confused.

As such, we don't want to get the working directory again later,
because that'd give us the wrong thing.  Also, setup.c has some nice
massaging of getcwd() from an absolute path into a relative path that
is much more convenient for us to do our later comparisons, and we'd
rather not do those additional tweaks with every check.  Since the
relative path from the project root to the _original_ current working
directory is a single value, a global seemed to make sense for saving
it.  Perhaps I should tweak it to be const as well.

>
> >
> > Signed-off-by: Elijah Newren <newren@gmail.com>
> > ---
> >  repository.c | 1 +
> >  repository.h | 1 +
> >  setup.c      | 2 ++
> >  3 files changed, 4 insertions(+)
> >
> > diff --git a/repository.c b/repository.c
> > index c5b90ba93ea..69a106c553c 100644
> > --- a/repository.c
> > +++ b/repository.c
> > @@ -17,6 +17,7 @@
> >  static struct repository the_repo;
> >  struct repository *the_repository;
> >  struct index_state the_index;
> > +char *the_cwd;
> >
> >  void initialize_the_repository(void)
> >  {
> > diff --git a/repository.h b/repository.h
> > index a057653981c..45de85d18ef 100644
> > --- a/repository.h
> > +++ b/repository.h
> > @@ -147,6 +147,7 @@ struct repository {
> >  };
> >
> >  extern struct repository *the_repository;
> > +extern char *the_cwd;
> >
> >  /*
> >   * Define a custom repository layout. Any field can be NULL, which
> > diff --git a/setup.c b/setup.c
> > index 347d7181ae9..4466fa55af3 100644
> > --- a/setup.c
> > +++ b/setup.c
> > @@ -887,6 +887,7 @@ static const char *setup_explicit_git_dir(const char *gitdirenv,
> >               set_git_dir(gitdirenv, 1);
> >               if (chdir(worktree))
> >                       die_errno(_("cannot chdir to '%s'"), worktree);
> > +             the_cwd = xstrdup(cwd->buf + offset);
> >               strbuf_addch(cwd, '/');
> >               free(gitfile);
> >               return cwd->buf + offset;
> > @@ -940,6 +941,7 @@ static const char *setup_discovered_git_dir(const char *gitdir,
> >       /* Make "offset" point past the '/' (already the case for root dirs) */
> >       if (offset != offset_1st_component(cwd->buf))
> >               offset++;
> > +     the_cwd = xstrdup(cwd->buf + offset);
> >       /* Add a '/' at the end */
> >       strbuf_addch(cwd, '/');
> >       return cwd->buf + offset;
> >
>