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From: "Martin Ågren" <martin.agren@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: "brian m. carlson" <sandals@crustytoothpaste.net>,
	Git Mailing List <git@vger.kernel.org>,
	Derrick Stolee <stolee@gmail.com>
Subject: Re: [PATCH 3/5] protocol-capabilities.txt: clarify "allow-x-sha1-in-want" re SHA-256
Date: Fri, 14 Aug 2020 22:35:10 +0200	[thread overview]
Message-ID: <CAN0heSpv5L67hYSX44LkwQ1pJ+_px_W=FQ4piXKS1anpMi0n2w@mail.gmail.com> (raw)
In-Reply-To: <xmqqft8pxhd9.fsf@gitster.c.googlers.com>

On Fri, 14 Aug 2020 at 19:33, Junio C Hamano <gitster@pobox.com> wrote:
>
> Martin Ågren <martin.agren@gmail.com> writes:
>
> > Two of our extensions contain "sha1" in their names, but that's
> > historical. The "want"s will take object names that are not necessarily
> > SHA-1s. Make this clear, but also make it clear how there's still just
> > one correct hash algo: These extensions don't somehow make the "want"s
> > take object names derived using *any* hash algorithm.
> >
> > Signed-off-by: Martin Ågren <martin.agren@gmail.com>
> > ---
> >  Documentation/technical/protocol-capabilities.txt | 11 +++++++----
> >  1 file changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/Documentation/technical/protocol-capabilities.txt b/Documentation/technical/protocol-capabilities.txt
> > index 36ccd14f97..47f1b30090 100644
> > --- a/Documentation/technical/protocol-capabilities.txt
> > +++ b/Documentation/technical/protocol-capabilities.txt
> > @@ -324,15 +324,18 @@ allow-tip-sha1-in-want
> >  ----------------------
> >
> >  If the upload-pack server advertises this capability, fetch-pack may
> > -send "want" lines with SHA-1s that exist at the server but are not
> > -advertised by upload-pack.
> > +send "want" lines with object names that exist at the server but are not
> > +advertised by upload-pack. (Note that the name of the capability
> > +contains "sha1", but that it's more general than that: in SHA-1
> > +repositories, the "want" lines provide SHA-1 values, but in SHA-256
> > +repositories, they provide SHA-256 values.)
>
> I think we should have either a new sha256 capability or a more
> generic hash-algo capability whose value can be set to sha256.
> Neither the connection initiators or the acceptors should talk
> in sha256 until both ends agreed to do so.

I think we should, and I think we do. I haven't dug into the details,
but "object-format" looks like it's just that.

Maybe instead of SHA-1 and SHA-256, this should talk about "whatever has
been negotiated through 'object-format', or SHA-1", similar to brian's
suggestion elsewhere.

> I do not think of any other way to make sure hosting sites to serve
> projects that migrate at different pace.  Per project, you might be
> able to have a flag day.  You cannot have a flag day that spans the
> world.

Yeah, that makes sense.


Martin

  reply	other threads:[~2020-08-14 20:35 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-13 22:48 [PATCH 0/2] Documentation updates for SHA-256 brian m. carlson
2020-08-13 22:49 ` [PATCH 1/2] docs: document SHA-256 pack and indices brian m. carlson
2020-08-14  2:26   ` Derrick Stolee
2020-08-13 22:49 ` [PATCH 2/2] docs: fix step in transition plan brian m. carlson
2020-08-14 12:21   ` Martin Ågren
2020-08-14  2:33 ` [PATCH 0/2] Documentation updates for SHA-256 Derrick Stolee
2020-08-14  4:47   ` Junio C Hamano
2020-08-14 20:20     ` brian m. carlson
2020-08-14 20:25       ` Junio C Hamano
2020-08-14 12:21 ` [PATCH 0/5] more SHA-256 documentation Martin Ågren
2020-08-14 12:21   ` [PATCH 1/5] http-protocol.txt: document SHA-256 "want"/"have" format Martin Ågren
2020-08-14 17:28     ` Junio C Hamano
2020-08-14 20:23       ` brian m. carlson
2020-08-14 20:32         ` Martin Ågren
2020-08-14 20:39         ` Junio C Hamano
2020-08-14 20:47           ` Junio C Hamano
2020-08-14 12:21   ` [PATCH 2/5] index-format.txt: document SHA-256 index format Martin Ågren
2020-08-14 12:28     ` Derrick Stolee
2020-08-14 14:05       ` Martin Ågren
2020-08-14 12:21   ` [PATCH 3/5] protocol-capabilities.txt: clarify "allow-x-sha1-in-want" re SHA-256 Martin Ågren
2020-08-14 12:31     ` Derrick Stolee
2020-08-14 14:05       ` Martin Ågren
2020-08-14 17:33     ` Junio C Hamano
2020-08-14 20:35       ` Martin Ågren [this message]
2020-08-14 20:43         ` Junio C Hamano
2020-08-14 12:21   ` [PATCH 4/5] shallow.txt: document SHA-256 shallow format Martin Ågren
2020-08-14 12:21   ` [PATCH 5/5] commit-graph-format.txt: fix "Hash Version" description Martin Ågren
2020-08-14 12:37     ` Derrick Stolee
2020-08-14 14:10       ` Martin Ågren
2020-08-14 20:28   ` [PATCH 0/5] more SHA-256 documentation brian m. carlson
2020-08-15 16:05   ` [PATCH v2 0/4] " Martin Ågren
2020-08-15 16:05     ` [PATCH v2 1/4] http-protocol.txt: document SHA-256 "want"/"have" format Martin Ågren
2020-08-15 16:06     ` [PATCH v2 2/4] index-format.txt: document SHA-256 index format Martin Ågren
2020-08-15 16:06     ` [PATCH v2 3/4] protocol-capabilities.txt: clarify "allow-x-sha1-in-want" re SHA-256 Martin Ågren
2020-08-15 16:06     ` [PATCH v2 4/4] shallow.txt: document SHA-256 shallow format Martin Ågren

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