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([2600:1700:e72:80a0:7dfc:cd76:faf5:aaad]) by smtp.gmail.com with ESMTPSA id s30sm8922490qtc.87.2020.08.13.19.33.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 13 Aug 2020 19:33:20 -0700 (PDT) Subject: Re: [PATCH 0/2] Documentation updates for SHA-256 To: "brian m. carlson" , git@vger.kernel.org Cc: =?UTF-8?Q?Martin_=c3=85gren?= References: <20200813224901.2652387-1-sandals@crustytoothpaste.net> From: Derrick Stolee Message-ID: Date: Thu, 13 Aug 2020 22:33:20 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:80.0) Gecko/20100101 Thunderbird/80.0 MIME-Version: 1.0 In-Reply-To: <20200813224901.2652387-1-sandals@crustytoothpaste.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On 8/13/2020 6:48 PM, brian m. carlson wrote: > As was pointed out recently, some of our documentation doesn't properly > reflect the new support for SHA-256. Just to bring up some subtlety in Martin's message [1], there is some valid concern that the existing file formats are not correctly versioned "in a vacuum." When they are in a repository that has SHA-256 set as its hash algorithm, Git interprets these file formats correctly, but if a *.pack file (and its *.idx) happened to be copied into the pack directory of a Git repository still in SHA-1 mode, then Git would get confused and probably fail miserably. Is that really a concern? Maybe, but also Git will never move data like that. The main thing is to focus on compatibility of the .git directory as a whole (and the protocol, as we move into inter-operability mode). [1] https://lore.kernel.org/git/CAN0heSptiJL9d86ZeNPMUaZeTA68juwTyf3K-uWR=K-vt=1Hrg@mail.gmail.com/ > This series updates the pack and > index documentation to reflect that these formats can handle SHA-256, > and updates the transition plan to reflect what we've implemented and > what the next steps are. These patches are good to help clarify these formats in the new world. Thanks, -Stolee