Re: weaning distributions off tarballs: extended verification of git tags

From: Sam Vilain <sam@vilain.net>
Date: Mar 2, 2015, 19:38 UTC
Message-ID: <54F4BC18.5060702@vilain.net>
In-Reply-To: <20150302181230.GA31798@kitenet.net>

On 03/02/2015 10:12 AM, Joey Hess wrote:

Show 10 quoted lines

> I support this proposal, as someone who no longer releases tarballs
> of my software, when I can possibly avoid it. I have worried about
> signed tags / commits only being a SHA1 break away from useless.
>
> As to the implementation, checksumming the collection of raw objects is
> certainly superior to tar. Colin had suggested sorting the objects by
> checksum, but I don't think that is necessary. Just stream the commit
> object, then its tree object, followed by the content of each object
> listed in the tree, recursing into subtrees as necessary. That will be a
> stable stream for a given commit, or tree.

I would really just do it exactly the same way that git does: checksum the objects including their headers with the new hashes. I have a hazy recollection of what it would take to replace SHA-1 in git with something else; it should be possible (though tricky) to do it lazily, where a tree entry has bits (eg, some of the currently unused file mode bits) to denotes which hash algorithm is in use for the entry. However I don't think that got past idea stage...

Sam