[OE-core] [RFC][PATCH 2/2] buildhistory: support generating md5sum of files

[Richard Purdie]

On Mon, 2019-01-07 at 10:38 +0100, Jacob Kroon wrote:
> On Mon, Jan 7, 2019 at 12:09 AM André Draszik <git at andred.net> wrote:
> > I don't know what the intended use-case of the md5 files is, but
> > could
> > sha256 or similar maybe be more appropriate?
> 
> I thought it would be a good idea to store some sort of checksum of
> files in the
> buildhistory when doing reproducible builds, so that it is easier to
> detect
> when a rebuild produces changed files, but perhaps there is some way
> to do
> this already that I am missing ?
> 
> But I have no real motivation for choosing md5, other than that I
> assumed it would be less
> cpu intensive than sha256, and the fact I'm not too worried about
> collisions.

I used to lean that way as well however there is a fair bit of
negativity associated with *any* use of md5 so I'm tempted to say use
sha256 as we don't know how these checksums may be used in the future.

I'd note there is some overlap here with the sstate hash equivalency
work where we build a hash representing a tasks complete output. Can
you reuse any of the functions there?

Cheers,

Richard