From: Patrick Steinhardt <ps@pks.im>
To: Junio C Hamano <gitster@pobox.com>
Cc: Karthik Nayak <karthik.188@gmail.com>,
Chris Torek <chris.torek@gmail.com>,
git@vger.kernel.org
Subject: Re: [PATCH 7/8] refs: add 'update-symref' command to 'update-ref'
Date: Wed, 10 Apr 2024 19:31:59 +0200 [thread overview]
Message-ID: <ZhbND7flvT7INnrz@ncase> (raw)
In-Reply-To: <xmqqzfu1w6ay.fsf@gitster.g>
[-- Attachment #1: Type: text/plain, Size: 3533 bytes --]
On Wed, Apr 10, 2024 at 09:06:45AM -0700, Junio C Hamano wrote:
> Patrick Steinhardt <ps@pks.im> writes:
>
> >> > I might have missed it while scanning through this thread, but why
> >> > exactly is the zero OID not a good enough placeholder here to say that
> >> > the ref must not exist? A symref cannot point to a ref named after the
> >> > zero OID anyway.
> >
> >> > In my opinion, "update-symref" with an old-value must be able to accept
> >> > both object IDs and symrefs as old value. Like this it would be possible
> >> > to update a proper ref to a symref in a race-free way. So you can say:
> >> >
> >> > git update-ref SYMREF refs/heads/main 19981daefd7c147444462739375462b49412ce33
> >
> >> > To update "SYRMEF" to "refs/heads/main", but only in case it currently
> >> > is a proper ref that points to 19981daefd7c147444462739375462b49412ce33.
> >> > Similarly...
> >> >
> >> > git update-ref SYMREF refs/heads/main refs/heads/master
> >
> >> > would update "SYMREF" to "refs/heads/main", but only if it currently
> >> > points to the symref "refs/heads/master".
>
> I think that would work well. We need to explicitly forbid a file
> $GIT_DIR/[0-9a-f]{40} to be used as a pseudoref, which I think that
> is an improvement. I do not know how the transition to move to a
> world with a stricter rule would look like, though.
I thought that Git already refuses such refnames anyway. Otherwise it
would be impossible to distinguish a ref called [0-9a-f]{40} from the
actual object hash in much of our tooling. I certainly know that GitLab
does refuse such refnames, and thought that GitHub does, too.
But turns out that at least git-update-ref(1) is happy to write such
refs:
```
$ git update-ref 1111111111111111111111111111111111111111 HEAD
$ cat .git/1111111111111111111111111111111111111111
cf6ba211cd2fce88f5d22d9f036029d502565509
```
What does it resolve to?
```
$ git rev-parse --verify 1111111111111111111111111111111111111111
warning: refname '1111111111111111111111111111111111111111' is ambiguous.
Git normally never creates a ref that ends with 40 hex characters
because it will be ignored when you just specify 40-hex. These refs
may be created by mistake. For example,
git switch -c $br $(git rev-parse ...)
where "$br" is somehow empty and a 40-hex ref is created. Please
examine these refs and maybe delete them. Turn this message off by
running "git config advice.objectNameWarning false"
1111111111111111111111111111111111111111
```
It resolves to 1111111111111111111111111111111111111111 because it's a
valid object ID already. And what if we try to peel it?
```
$ git rev-parse --verify 1111111111111111111111111111111111111111^{commit}
warning: refname '1111111111111111111111111111111111111111' is ambiguous.
Git normally never creates a ref that ends with 40 hex characters
because it will be ignored when you just specify 40-hex. These refs
may be created by mistake. For example,
git switch -c $br $(git rev-parse ...)
where "$br" is somehow empty and a 40-hex ref is created. Please
examine these refs and maybe delete them. Turn this message off by
running "git config advice.objectNameWarning false"
fatal: Needed a single revision
```
Doesn't work.
So these refs essentially cannot be accessed anyway. Restricting
git-update-ref(1) such that it cannot write them in the first place thus
shouldn't be breaking much, I'd claim, and feels like a strict
improvement overall.
Patrick
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
next prev parent reply other threads:[~2024-04-10 17:32 UTC|newest]
Thread overview: 194+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-30 22:46 [PATCH 0/8] update-ref: add support for update-symref option Karthik Nayak
2024-03-30 22:46 ` [PATCH 1/8] files-backend: extract out `create_symref_lock` Karthik Nayak
2024-04-02 12:20 ` Patrick Steinhardt
2024-04-03 14:52 ` Karthik Nayak
2024-03-30 22:46 ` [PATCH 2/8] reftable-backend: extract out `write_symref_with_log` Karthik Nayak
2024-04-02 12:20 ` Patrick Steinhardt
2024-03-30 22:46 ` [PATCH 3/8] reftable-backend: move `write_symref_with_log` up Karthik Nayak
2024-03-30 22:46 ` [PATCH 4/8] refs: accept symref in `ref_transaction_add_update` Karthik Nayak
2024-03-30 22:46 ` [PATCH 5/8] refs/files-backend: add support for symref updates Karthik Nayak
2024-04-02 12:20 ` Patrick Steinhardt
2024-03-30 22:46 ` [PATCH 6/8] refs/reftable-backend: " Karthik Nayak
2024-04-02 12:20 ` Patrick Steinhardt
2024-03-30 22:46 ` [PATCH 7/8] refs: add 'update-symref' command to 'update-ref' Karthik Nayak
2024-03-31 22:08 ` Junio C Hamano
2024-03-31 22:27 ` Chris Torek
2024-03-31 23:14 ` Junio C Hamano
2024-04-01 1:31 ` Junio C Hamano
2024-04-02 12:20 ` Patrick Steinhardt
2024-04-02 16:40 ` Junio C Hamano
2024-04-09 11:55 ` Patrick Steinhardt
2024-04-09 16:15 ` Karthik Nayak
2024-04-10 4:20 ` Patrick Steinhardt
2024-04-10 16:06 ` Junio C Hamano
2024-04-10 17:31 ` Patrick Steinhardt [this message]
2024-04-01 10:38 ` Karthik Nayak
2024-04-01 11:48 ` Karthik Nayak
2024-04-01 16:17 ` Junio C Hamano
2024-04-01 20:40 ` Junio C Hamano
2024-04-01 22:37 ` Karthik Nayak
2024-03-30 22:46 ` [PATCH 8/8] refs: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-04-02 12:20 ` Patrick Steinhardt
2024-04-12 9:59 ` [PATCH v2 0/7] update-ref: add symref oriented commands Karthik Nayak
2024-04-12 9:59 ` [PATCH v2 1/7] refs: accept symref values in `ref_transaction[_add]_update` Karthik Nayak
2024-04-18 14:25 ` Christian Couder
2024-04-19 10:28 ` Karthik Nayak
2024-04-18 15:08 ` Phillip Wood
2024-04-19 9:40 ` Patrick Steinhardt
2024-04-19 15:47 ` Karthik Nayak
2024-05-04 15:15 ` phillip.wood123
2024-04-19 9:40 ` Patrick Steinhardt
2024-04-19 18:09 ` Karthik Nayak
2024-04-23 6:31 ` Patrick Steinhardt
2024-04-23 10:48 ` Karthik Nayak
2024-04-12 9:59 ` [PATCH v2 2/7] update-ref: add support for symref-verify Karthik Nayak
2024-04-18 14:26 ` Christian Couder
2024-04-19 21:21 ` Karthik Nayak
2024-04-19 9:40 ` Patrick Steinhardt
2024-04-19 21:53 ` Karthik Nayak
2024-04-12 9:59 ` [PATCH v2 3/7] update-ref: add support for symref-delete Karthik Nayak
2024-04-18 14:52 ` Christian Couder
2024-04-21 10:43 ` Karthik Nayak
2024-04-19 9:40 ` Patrick Steinhardt
2024-04-21 10:45 ` Karthik Nayak
2024-04-12 9:59 ` [PATCH v2 4/7] files-backend: extract out `create_symref_lock` Karthik Nayak
2024-04-12 9:59 ` [PATCH v2 5/7] update-ref: add support for symref-create Karthik Nayak
2024-04-19 9:40 ` Patrick Steinhardt
2024-04-19 15:48 ` Junio C Hamano
2024-04-21 12:50 ` Karthik Nayak
2024-04-21 15:57 ` Karthik Nayak
2024-04-23 6:39 ` Patrick Steinhardt
2024-04-23 10:52 ` Karthik Nayak
2024-04-12 9:59 ` [PATCH v2 6/7] update-ref: add support for symref-update Karthik Nayak
2024-04-19 9:40 ` Patrick Steinhardt
2024-04-21 19:00 ` Karthik Nayak
2024-04-23 6:49 ` Patrick Steinhardt
2024-04-23 11:30 ` Karthik Nayak
2024-04-12 9:59 ` [PATCH v2 7/7] refs: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-04-12 18:01 ` [PATCH v2 0/7] update-ref: add symref oriented commands Junio C Hamano
2024-04-12 18:49 ` Karthik Nayak
2024-04-18 15:05 ` Christian Couder
2024-04-21 19:06 ` Karthik Nayak
2024-04-20 6:16 ` Patrick Steinhardt
2024-04-21 19:11 ` Karthik Nayak
2024-04-23 21:28 ` [PATCH v3 0/8] refs: add symref support to 'git-update-ref' Karthik Nayak
2024-04-23 21:28 ` [PATCH v3 1/8] refs: accept symref values in `ref_transaction[_add]_update` Karthik Nayak
2024-04-23 21:28 ` [PATCH v3 2/8] update-ref: support parsing ref targets in `parse_next_oid` Karthik Nayak
2024-04-23 21:28 ` [PATCH v3 3/8] files-backend: extract out `create_symref_lock` Karthik Nayak
2024-04-23 21:28 ` [PATCH v3 4/8] update-ref: support symrefs in the verify command Karthik Nayak
2024-04-23 21:28 ` [PATCH v3 5/8] update-ref: support symrefs in the delete command Karthik Nayak
2024-04-23 21:28 ` [PATCH v3 6/8] update-ref: support symrefs in the create command Karthik Nayak
2024-04-23 21:28 ` [PATCH v3 7/8] update-ref: support symrefs in the update command Karthik Nayak
2024-04-23 21:28 ` [PATCH v3 8/8] ref: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-04-23 22:03 ` [PATCH v3 0/8] refs: add symref support to 'git-update-ref' Jeff King
2024-04-24 1:17 ` Junio C Hamano
2024-04-24 16:25 ` Karthik Nayak
2024-04-25 6:40 ` Patrick Steinhardt
2024-04-25 21:12 ` Karthik Nayak
2024-04-25 18:01 ` Junio C Hamano
2024-04-25 21:14 ` Karthik Nayak
2024-04-25 21:55 ` Junio C Hamano
2024-04-26 12:48 ` Karthik Nayak
2024-04-26 20:41 ` Jeff King
2024-04-25 17:09 ` Junio C Hamano
2024-04-25 21:07 ` Karthik Nayak
2024-04-26 15:24 ` [PATCH v4 0/7] add symref-* commands to 'git-update-ref --stdin' Karthik Nayak
2024-04-26 15:24 ` [PATCH v4 1/7] refs: accept symref values in `ref_transaction[_add]_update` Karthik Nayak
2024-04-26 19:31 ` Junio C Hamano
2024-04-26 21:15 ` Jeff King
2024-04-29 7:02 ` Patrick Steinhardt
2024-04-29 7:55 ` Jeff King
2024-04-29 9:29 ` phillip.wood123
2024-04-29 9:32 ` phillip.wood123
2024-04-29 16:18 ` Junio C Hamano
2024-04-30 10:33 ` Jeff King
2024-04-30 10:30 ` Jeff King
2024-04-28 19:36 ` Karthik Nayak
2024-04-29 13:38 ` Phillip Wood
2024-04-29 14:01 ` Karthik Nayak
2024-04-26 15:24 ` [PATCH v4 2/7] files-backend: extract out `create_symref_lock` Karthik Nayak
2024-04-26 21:39 ` Junio C Hamano
2024-04-28 19:57 ` Karthik Nayak
2024-04-26 15:24 ` [PATCH v4 3/7] update-ref: add support for 'symref-verify' command Karthik Nayak
2024-04-26 22:51 ` Junio C Hamano
2024-04-28 22:28 ` Karthik Nayak
2024-04-26 15:24 ` [PATCH v4 4/7] update-ref: add support for 'symref-delete' command Karthik Nayak
2024-04-26 15:24 ` [PATCH v4 5/7] update-ref: add support for 'symref-create' command Karthik Nayak
2024-04-26 15:24 ` [PATCH v4 6/7] update-ref: add support for 'symref-update' command Karthik Nayak
2024-04-26 15:24 ` [PATCH v4 7/7] ref: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-04-30 10:14 ` [PATCH v4 0/7] add symref-* commands to 'git-update-ref --stdin' Karthik Nayak
2024-05-01 20:22 ` [PATCH v5 0/7] refs: add support for transactional symref updates Karthik Nayak
2024-05-01 20:22 ` [PATCH v5 1/7] refs: accept symref values in `ref_transaction_update()` Karthik Nayak
2024-05-01 20:22 ` [PATCH v5 2/7] files-backend: extract out `create_symref_lock()` Karthik Nayak
2024-05-01 22:06 ` Junio C Hamano
2024-05-02 7:47 ` Patrick Steinhardt
2024-05-02 11:05 ` Karthik Nayak
2024-05-02 16:49 ` Junio C Hamano
2024-05-01 20:22 ` [PATCH v5 3/7] refs: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-05-01 23:05 ` Junio C Hamano
2024-05-02 5:32 ` Karthik Nayak
2024-05-01 20:22 ` [PATCH v5 4/7] refs: add support for transactional symref updates Karthik Nayak
2024-05-01 23:52 ` Junio C Hamano
2024-05-02 5:50 ` Karthik Nayak
2024-05-02 7:47 ` Patrick Steinhardt
2024-05-02 11:10 ` Karthik Nayak
2024-05-02 16:51 ` Junio C Hamano
2024-05-02 16:00 ` Junio C Hamano
2024-05-02 17:53 ` Junio C Hamano
2024-05-01 20:22 ` [PATCH v5 5/7] refs: use transaction in `refs_create_symref()` Karthik Nayak
2024-05-02 7:47 ` Patrick Steinhardt
2024-05-01 20:22 ` [PATCH v5 6/7] refs: rename `refs_create_symref()` to `refs_update_symref()` Karthik Nayak
2024-05-02 7:47 ` Patrick Steinhardt
2024-05-02 11:34 ` Karthik Nayak
2024-05-01 20:22 ` [PATCH v5 7/7] refs: remove `create_symref` and associated dead code Karthik Nayak
2024-05-02 7:47 ` Patrick Steinhardt
2024-05-02 16:53 ` Junio C Hamano
2024-05-02 0:20 ` [PATCH v5 0/7] refs: add support for transactional symref updates Junio C Hamano
2024-05-02 5:53 ` Karthik Nayak
2024-05-03 12:41 ` [PATCH v6 " Karthik Nayak
2024-05-03 12:41 ` [PATCH v6 1/7] refs: accept symref values in `ref_transaction_update()` Karthik Nayak
2024-05-04 15:18 ` Phillip Wood
2024-05-05 15:10 ` Karthik Nayak
2024-05-05 15:19 ` phillip.wood123
2024-05-03 12:41 ` [PATCH v6 2/7] files-backend: extract out `create_symref_lock()` Karthik Nayak
2024-05-03 12:41 ` [PATCH v6 3/7] refs: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-05-03 12:41 ` [PATCH v6 4/7] refs: add support for transactional symref updates Karthik Nayak
2024-05-05 14:09 ` Phillip Wood
2024-05-05 16:09 ` Karthik Nayak
2024-05-06 9:35 ` Phillip Wood
2024-05-06 11:19 ` Karthik Nayak
2024-05-06 13:19 ` Phillip Wood
2024-05-06 9:54 ` Phillip Wood
2024-05-06 11:22 ` Karthik Nayak
2024-05-06 13:17 ` Phillip Wood
2024-05-03 12:41 ` [PATCH v6 5/7] refs: use transaction in `refs_create_symref()` Karthik Nayak
2024-05-03 12:41 ` [PATCH v6 6/7] refs: rename `refs_create_symref()` to `refs_update_symref()` Karthik Nayak
2024-05-03 12:41 ` [PATCH v6 7/7] refs: remove `create_symref` and associated dead code Karthik Nayak
2024-05-03 23:09 ` Junio C Hamano
2024-05-04 9:30 ` Karthik Nayak
2024-05-03 16:45 ` [PATCH v6 0/7] refs: add support for transactional symref updates Junio C Hamano
2024-05-06 7:36 ` Patrick Steinhardt
2024-05-07 6:00 ` [PATCH v7 0/8] " Karthik Nayak
2024-05-07 6:00 ` [PATCH v7 1/8] refs: accept symref values in `ref_transaction_update()` Karthik Nayak
2024-05-07 6:00 ` [PATCH v7 2/8] files-backend: extract out `create_symref_lock()` Karthik Nayak
2024-05-07 6:00 ` [PATCH v7 3/8] refs: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-05-07 6:00 ` [PATCH v7 4/8] refs: move `original_update_refname` to 'refs.c' Karthik Nayak
2024-05-07 6:00 ` [PATCH v7 5/8] refs: add support for transactional symref updates Karthik Nayak
2024-05-07 6:00 ` [PATCH v7 6/8] refs: use transaction in `refs_create_symref()` Karthik Nayak
2024-05-07 6:00 ` [PATCH v7 7/8] refs: rename `refs_create_symref()` to `refs_update_symref()` Karthik Nayak
2024-05-07 6:00 ` [PATCH v7 8/8] refs: remove `create_symref` and associated dead code Karthik Nayak
2024-05-07 6:25 ` [PATCH v7 0/8] refs: add support for transactional symref updates Junio C Hamano
2024-05-07 6:31 ` Junio C Hamano
2024-05-07 12:58 ` [PATCH v8 " Karthik Nayak
2024-05-07 12:58 ` [PATCH v8 1/8] refs: accept symref values in `ref_transaction_update()` Karthik Nayak
2024-05-07 12:58 ` [PATCH v8 2/8] files-backend: extract out `create_symref_lock()` Karthik Nayak
2024-05-07 12:58 ` [PATCH v8 3/8] refs: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-05-07 12:58 ` [PATCH v8 4/8] refs: move `original_update_refname` to 'refs.c' Karthik Nayak
2024-05-07 12:58 ` [PATCH v8 5/8] refs: add support for transactional symref updates Karthik Nayak
2024-05-07 12:58 ` [PATCH v8 6/8] refs: use transaction in `refs_create_symref()` Karthik Nayak
2024-05-07 12:58 ` [PATCH v8 7/8] refs: rename `refs_create_symref()` to `refs_update_symref()` Karthik Nayak
2024-05-07 12:58 ` [PATCH v8 8/8] refs: remove `create_symref` and associated dead code Karthik Nayak
2024-05-07 15:50 ` [PATCH v8 0/8] refs: add support for transactional symref updates phillip.wood123
2024-05-07 16:32 ` Junio C Hamano
2024-05-12 17:17 ` Karthik Nayak
2024-05-13 17:15 ` Junio C Hamano
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZhbND7flvT7INnrz@ncase \
--to=ps@pks.im \
--cc=chris.torek@gmail.com \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.com \
--cc=karthik.188@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).