Re: [PATCH v5 3/3] cat-file: add --follow-symlinks to --batch

From: Junio C Hamano <gitster@pobox.com>
Date: May 12, 2015, 20:07 UTC
Message-ID: <xmqqh9rhftlh.fsf@gitster.dls.corp.google.com>
In-Reply-To: <1431455779.16652.20.camel@ubuntu>

David Turner <dturner@twopensource.com> writes:

Show 9 quoted lines

>>  * I am not sure if HEAD:link that points at HEAD:link should be
>>    reported as "missing".  It may be better to report the original
>>    without any dereferencing just like a link that points at outside
>>    the tree? i.e. "symlink 4 LF link".
>
> Unfortunately, a symlink loop might include relative symlinks
> (e.g. ../a).  If we return a relative symlink, the user will
> not be able to distinguish it from a non-loop, out-of-tree symlink.  So
> I think we may not return symlink 4 LF ../a for these cases.

I do not follow.  Let's start from a shared example.

    HEAD:sub/link is a symbolic link whose value is ../nextlink
    HEAD:nextlink is a symbolic link whose value is sub/link

That's a loop.  Now, I think what I am sugesting is

	$ git cat-file --batch-check --follow-symlinks <<\EOF
	HEAD:sub/link
        HEAD:nextlink
	EOF
	symlink ../nextlink
        symlink sub/link

If you asked about sub/link and then got ../nextlink back, then isn't it clear for the reading script that it is about nextlink at the top-level? Why can't it tell it from out-of-tree link?