From: Johannes Sixt <j6t@kdbg.org>
Date: Wed, 12 Sep 2018 20:48:04 GMT
Subject: Re: [Question] Signature calculation ignoring parts of binary files
Message-ID: <4102803b-d5de-5812-4cef-569c9869fed1@kdbg.org>
In-Reply-To: <003901d44acd$12c2bb90$384832b0$@nexbridge.com>

Am 12.09.18 um 21:16 schrieb Randall S. Becker:
> I feel really bad asking this, and I should know the answer, and yet.
> 
> I have a binary file that needs to go into a repo intact (unchanged). I also
> have a program that interprets the contents, like a textconv, that can
> output the relevant portions of the file in whatever format I like - used
> for diff typically, dumps in 1K chunks by file section. What I'm looking for
> is to have the SHA1 signature calculated with just the relevant portions of
> the file so that two actually different files will be considered the same by
> git during a commit or status. In real terms, I'm trying to ignore the
> Creator metadata of a JPG because it is mutable and irrelevant to my repo
> contents.
> 
> I'm sorry to ask, but I thought this was in .gitattributes but I can't
> confirm the SHA1 behaviour.

You are looking for a clean filter. See the 'filter' attribute in 
gitattributes(5). Your clean filter program or script should strip the 
unwanted metadata or set it to a constant known-good value.

(You shouldn't need a smudge filter.)

-- Hannes