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From: Junio C Hamano <gitster@pobox•com>
To: David Turner <dturner@twopensource•com>
Cc: git@vger•kernel.org, David Turner <dturner@twitter•com>
Subject: Re: [PATCH v5 3/3] cat-file: add --follow-symlinks to --batch
Date: Tue, 12 May 2015 13:22:15 -0700	[thread overview]
Message-ID: <xmqqd225fsw8.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <xmqqlhgtftw0.fsf@gitster.dls.corp.google.com> (Junio C. Hamano's message of "Tue, 12 May 2015 13:00:47 -0700")

Junio C Hamano <gitster@pobox•com> writes:

> Ahh, that would also give us "missing", so in that sense you are
> being consistent.
>
> But I do not think that consistency is useful.  Showing just
> "missing" instead is losing information and that is what bothers me.
>
> Showing "symlink 6 nosuch" to this "link points at a target that
> would be in-tree but there is no such object in the tree" symbolic
> link instead of "missing" would make it more useful, and I do not
> offhand think of a downside, but maybe I am missing something.
>
> For a link that points outside, the code already gives
>
>     $ ln -s ../outside outlink
>     $ git add outlink
>     $ echo "$(git write-tree):outlink" |
>       git cat-file --batch --follow-symlinks
>
> "symlink ../outside", so the script reading from the batch output
> already has to be prepared to handle "symlink" and understand it as
> saying "the link does not point an object that is inside the tree".

Having said all that, I think we can make readers' life easier by
classifying various reasons why --follow-symlinks cannot pretend
as if the in-tree pointee were given as its input and signal it
differently:

 * A link points outside the original tree (or the index, once we
   support "cat-file :RelNotes").

   I think your "symlink <size> LF <target> LF" already does this.

 * A link points (directly or indirectly) at itself.

   This would be your "loop <size> LF <target> LF", which I think is
   good.

 * A link does not step outside the original tree, but the pointee
   does not exist in the original tree.

   I think you currently say "<object name for HEAD:link> missing",
   but I do not think it is useful.  That object does exist, but it
   merely cannot be dereferenced.  Perhaps introducing a new one,
   e.g. "dangling <size> LF <target> LF" similar to symlink/loop,
   would help the reader better?

Are there other cases?  The only other case I think of is when the
link resolves cleanly inside the tree, which you already handle.

Thanks.

next prev parent reply	other threads:[~2015-05-12 20:22 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-11 22:50 [PATCH v5 0/3] cat-file --follow-symlinks dturner
2015-05-11 22:50 ` [PATCH v5 1/3] tree-walk: learn get_tree_entry_follow_symlinks dturner
2015-05-12 17:29   ` Johannes Sixt
2015-05-11 22:50 ` [PATCH v5 2/3] sha1_name: get_sha1_with_context learns to follow symlinks dturner
2015-05-11 22:50 ` [PATCH v5 3/3] cat-file: add --follow-symlinks to --batch dturner
2015-05-12 17:34   ` Johannes Sixt
2015-05-12 18:07   ` Junio C Hamano
2015-05-12 18:36     ` David Turner
2015-05-12 18:43       ` Junio C Hamano
2015-05-12 18:55         ` David Turner
2015-05-12 20:00           ` Junio C Hamano
2015-05-12 20:22             ` Junio C Hamano [this message]
2015-05-12 22:36               ` David Turner
2015-05-12 23:02                 ` Junio C Hamano
2015-05-12 23:06                   ` Junio C Hamano
2015-05-12 20:07       ` Junio C Hamano
2015-05-12 21:37         ` David Turner
2015-05-12 21:42           ` Junio C Hamano
2015-05-12 21:53             ` David Turner
2015-05-14 20:06       ` Junio C Hamano

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