From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Mike Hommey <mh@glandium.org>
Cc: Jeff King <peff@peff.net>, Shawn Pearce <spearce@spearce.org>,
Jonathan Tan <jonathantanmy@google.com>,
git <git@vger.kernel.org>
Subject: Re: [PATCH] fetch-pack: always allow fetching of literal SHA1s
Date: Wed, 10 May 2017 19:50:01 +0200 [thread overview]
Message-ID: <CACBZZX4AnmP2N_-WLtqQncUDCZDeWS3LFomZrWLYP6iW-hL5KA@mail.gmail.com> (raw)
In-Reply-To: <20170510044626.g4dwcujfr7vhv55d@glandium.org>
On Wed, May 10, 2017 at 6:46 AM, Mike Hommey <mh@glandium.org> wrote:
> On Wed, May 10, 2017 at 12:33:44AM -0400, Jeff King wrote:
>> On Tue, May 09, 2017 at 09:22:11PM -0700, Shawn Pearce wrote:
>>
>> > > Hmm. That makes sense generally, as the request should succeed. But it
>> > > seems like we're creating a client that will sometimes succeed and
>> > > sometimes fail, and the reasoning will be somewhat opaque to the user.
>> > > I have a feeling I'm missing some context on when you'd expect this to
>> > > kick in.
>> >
>> > Specifically, someone I know was looking at building an application
>> > that is passed only a SHA-1 for the tip of a ref on a popular hosting
>> > site[1]. They wanted to run `git fetch URL SHA1`, but this failed
>> > because the site doesn't have upload.allowtipsha1inwant enabled.
>> > However the SHA1 was clearly in the output of git ls-remote.
>>
>> OK. So this is basically a case where we expect that the user knows what
>> they're doing.
>>
>> > For various reasons they expected this to work, because it works
>> > against other sites that do have upload.allowtipsha1inwant enabled.
>> > And I personally just expected it to work because the fetch client
>> > accepts SHA-1s, and the wire protocol uses "want SHA1" not "want ref",
>> > and the SHA-1 passed on the command line was currently in the
>> > advertisement when the connection opened, so its certainly something
>> > the server is currently willing to serve.
>>
>> Right, makes sense. I wondered if GitHub should be turning on
>> allowTipSHA1InWant, but it really doesn't make sense to. We _do_ hide
>> some internal refs[1], and they're things that users wouldn't want to
>> fetch. The problem for your case really is just on the client side, and
>> this patch fixes it.
>
> More broadly, I think it is desirable that any commit that can be
> reached from public refs can be fetched by an explicit sha1 without
> allowTipSHA1InWant.
Just a side question, what are the people who use this feature using
it for? The only thing I can think of myself is some out of band ref
advertisement because you've got squillions of refs as a hack around
git's limitations in that area.
Are there other use-cases for this? All the commits[1] that touched
this feature just explain what, not why.
1. git log --reverse -p -i -Gallowtipsha1inwant
next prev parent reply other threads:[~2017-05-10 17:50 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-09 18:20 [PATCH] fetch-pack: always allow fetching of literal SHA1s Jonathan Tan
2017-05-09 22:16 ` Jeff King
2017-05-10 4:22 ` Shawn Pearce
2017-05-10 4:33 ` Jeff King
2017-05-10 4:46 ` Mike Hommey
2017-05-10 17:50 ` Ævar Arnfjörð Bjarmason [this message]
2017-05-10 18:20 ` Jonathan Nieder
2017-05-10 18:48 ` Martin Fick
2017-05-10 18:54 ` Jonathan Nieder
2017-05-10 4:57 ` Shawn Pearce
2017-05-10 17:00 ` Jonathan Nieder
2017-05-10 18:55 ` Sebastian Schuberth
2017-05-11 9:59 ` Jeff King
2017-05-11 19:03 ` Jonathan Nieder
2017-05-11 21:04 ` Jeff King
2017-05-10 16:44 ` [PATCH v2] " Jonathan Tan
2017-05-10 18:01 ` Jonathan Nieder
2017-05-10 22:11 ` [PATCH v3] " Jonathan Tan
2017-05-10 23:22 ` Jonathan Nieder
2017-05-11 9:46 ` Jeff King
2017-05-11 17:51 ` Jonathan Tan
2017-05-11 20:52 ` Jeff King
2017-05-11 10:05 ` Jeff King
2017-05-11 17:00 ` Brandon Williams
2017-05-13 9:29 ` Jeff King
2017-05-11 21:14 ` [PATCH v4] " Jonathan Tan
2017-05-11 21:35 ` Jonathan Nieder
2017-05-11 21:59 ` Jeff King
2017-05-11 22:30 ` [PATCH v5] " Jonathan Tan
2017-05-11 22:46 ` Jonathan Nieder
2017-05-12 2:59 ` Jeff King
2017-05-12 6:01 ` Junio C Hamano
2017-05-12 7:59 ` Jeff King
2017-05-12 8:14 ` Jeff King
2017-05-12 18:00 ` Jonathan Tan
2017-05-13 8:30 ` Jeff King
2017-05-12 18:09 ` Jonathan Tan
2017-05-12 19:06 ` Jonathan Nieder
2017-05-12 3:06 ` Jeff King
2017-05-12 20:45 ` Jonathan Tan
2017-05-12 20:46 ` [PATCH v6] " Jonathan Tan
2017-05-12 22:28 ` Jonathan Nieder
2017-05-13 8:36 ` Jeff King
2017-05-15 1:26 ` Junio C Hamano
2017-05-15 17:32 ` [PATCH v7] " Jonathan Tan
2017-05-15 17:46 ` Jonathan Nieder
2017-05-15 22:10 ` Jeff King
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