Re: [PATCH v2] receive-pack: purge temporary data if no command is ready to run

[Bojun Chen <bojun.cbj@gmail.com>]

Junio C Hamano <gitster@pobox.com> 于2022年2月2日周三 06:51写道：
>
> Chen BoJun <bojun.cbj@gmail.com> writes:
>
> > From: Chen Bojun <bojun.cbj@alibaba-inc.com>
> >
> > When pushing a hidden ref, e.g.:
> >
> >     $ git push origin HEAD:refs/hidden/foo
> >
> > "receive-pack" will reject our request with an error message like this:
> >
> >     ! [remote rejected] HEAD -> refs/hidden/foo (deny updating a hidden ref)
> >
> > The remote side ("git-receive-pack") will not create the hidden ref as
> > expected, but the pack file sent by "git-send-pack" is left inside the
> > remote repository. I.e. the quarantine directory is not purged as it
> > should be.
>
> I was puzzled by the reference to "pushing a hidden ref" at the
> beginning of the proposed log message, as it wasn't quite clear that
> it was merely an easy-to-reproduce recipe to fall into such a
> situation where all ref updates are rejected.
>

Thanks for the suggestion. Do I have to rewrite this commit message on the v3?

> But the code change makes the function leave before the object
> migration out of the quarantine when no ref updates are done for any
> reason, andit makes perfect sense.  The title reflects it very well.
>
> > Add a checkpoint before calling "tmp_objdir_migrate()" and after calling
> > the "pre-receive" hook to purge that temporary data in the quarantine
> > area when there is no command ready to run.
>
> OK.
>
> I wondered how this should interact with the "proc_receive_ref"
> stuff, but existing code makes proc_receive_ref ignored when
> pre-receive rejects, so doing the same would be OK.
>
> > index 9f4a0b816c..a0b193ab3f 100644
> > --- a/builtin/receive-pack.c
> > +++ b/builtin/receive-pack.c
> > @@ -1971,6 +1971,15 @@ static void execute_commands(struct command *commands,
> >               return;
> >       }
>
> With the new logic, "return;" we see above becomes unnecessary.  I
> wonder if it is a good idea to keep it or remove it.
>
> > +     /*
> > +      * If there is no command ready to run, should return directly to destroy
> > +      * temporary data in the quarantine area.
> > +      */
> > +     for (cmd = commands; cmd && cmd->error_string; cmd = cmd->next)
> > +             ; /* nothing */
> > +     if (!cmd)
> > +             return;
> > +
> >       /*
> >        * Now we'll start writing out refs, which means the objects need
> >        * to be in their final positions so that other processes can see them.
> > diff --git a/t/t5516-fetch-push.sh b/t/t5516-fetch-push.sh
> > index 2f04cf9a1c..da70c45857 100755
> > --- a/t/t5516-fetch-push.sh
> > +++ b/t/t5516-fetch-push.sh
> > @@ -1809,4 +1809,12 @@ test_expect_success 'refuse fetch to current branch of bare repository worktree'
> >       git -C bare.git fetch -u .. HEAD:wt
> >  '
> >
> > +test_expect_success 'refuse to push a hidden ref, and make sure do not pollute the repository' '
> > +     mk_empty testrepo &&
> > +     git -C testrepo config receive.hiderefs refs/hidden &&
> > +     git -C testrepo config receive.unpackLimit 1 &&
> > +     test_must_fail git push testrepo HEAD:refs/hidden/foo &&
> > +     test_dir_is_empty testrepo/.git/objects/pack
> > +'
> > +
> >  test_done

Thanks for your thorough comments. It's really helpful.