Re: [PATCH v2 2/2] setup: allow Git.pm to do unsafe repo checking

From: Jeff King <peff@peff.net>
Date: Oct 22, 2022, 21:18 UTC
Message-ID: <Y1ReKB701QXRv64A@coredump.intra.peff.net>
In-Reply-To: <xmqq1qr0ifya.fsf@gitster.g>

On Fri, Oct 21, 2022 at 10:29:33PM -0700, Junio C Hamano wrote:

Show 11 quoted lines

> I also have to wonder (and this is *not* a suggestion for inventing
> an alternative fix for perl/Git.pm) if we were creating perl/Git.pm
> from scratch today, we even need to be worried about this issue.  We
> may have Git::repo_path() helper but if we call it in a natural way
> (read: as if an interactive end-user would type commands), it is
> likely that we would run "git rev-parse --git-dir" or something
> without setting GIT_DIR, and when we need to run "git" command, say
> "git diff", we would also run "git diff" as if the end user would
> type from within their interactive session and without setting
> GIT_DIR, and everything should work.  IOW, why do we even setting
> and exporting the auto-detected value in GIT_DIR?

I think it has to in order to avoid surprises. If I do this:

  perl -MGit -e '
    my $r = Git->repository;
    chdir("/somewhere/else");
    $r->git_command(...);
  '

that command ought to run in the repository I opened earlier. So I think to keep the illusion of a lib-ified object, creating that object has to lock in the path.

But it really seems like we should be asking rev-parse what that path is, not trying to do any magic ourselves.

-Peff