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From: "Martin Ågren" <martin.agren@gmail.com>
To: "brian m. carlson" <sandals@crustytoothpaste.net>
Cc: git@vger.kernel.org, Derrick Stolee <stolee@gmail.com>,
	Junio C Hamano <gitster@pobox.com>
Subject: [PATCH 5/5] commit-graph-format.txt: fix "Hash Version" description
Date: Fri, 14 Aug 2020 14:21:46 +0200	[thread overview]
Message-ID: <bbcd97db8a2c94343950bb0cf8cbd5c9c01b4577.1597406877.git.martin.agren@gmail.com> (raw)
In-Reply-To: <cover.1597406877.git.martin.agren@gmail.com>

We say that value 1 means "SHA-1", but in fact, it means "whatever
the_hash_algo is", see commit c166599862 ("commit-graph: convert to
using the_hash_algo", 2018-11-14).

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
---
 If we want to be more fine-grained in the future, we'll need to say,
 e.g., "2 means SHA-1, 3 means SHA-256" or, perhaps preferrably, bump the
 version number.

 I wonder: Should we instead say "1 means SHA-1, 2 means SHA-256"? It
 could be implemented as "easily" as "if (value_from_header !=
 value_from_the_hash_algo) die(...);" for now. Might that pay off in the
 long run?

 This relates to Stolee's "in a vacuum" comment [1] ... so maybe we're
 fine.

 [1] https://lore.kernel.org/git/da077fb0-14bb-b84f-c526-d759ebc9f5eb@gmail.com/

 Documentation/technical/commit-graph-format.txt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/technical/commit-graph-format.txt b/Documentation/technical/commit-graph-format.txt
index 440541045d..3535426d32 100644
--- a/Documentation/technical/commit-graph-format.txt
+++ b/Documentation/technical/commit-graph-format.txt
@@ -42,8 +42,8 @@ HEADER:
   1-byte version number:
       Currently, the only valid version is 1.
 
-  1-byte Hash Version (1 = SHA-1)
-      We infer the hash length (H) from this value.
+  1-byte Hash Version (1 = SHA-1 in SHA-1 repo, SHA-256 in SHA-256 repo)
+      We infer the hash length (H) from the hash algo derived from this value.
 
   1-byte number (C) of "chunks"
 
-- 
2.28.0.277.g9b3c35fffd


  parent reply	other threads:[~2020-08-14 12:22 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
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   ` Martin Ågren [this message]
2020-08-14 12:37     ` [PATCH 5/5] commit-graph-format.txt: fix "Hash Version" description 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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