From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christopher Lemmer Webber Subject: Re: Graft hooks Date: Sun, 12 Aug 2018 20:28:00 -0400 Message-ID: <87ftzjf6un.fsf@dustycloud.org> References: <87k1ovbc0t.fsf@ngyro.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Return-path: Received: from eggs.gnu.org ([2001:4830:134:3::10]:39475) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fp0iL-0004CW-B9 for guix-devel@gnu.org; Sun, 12 Aug 2018 20:28:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fp0iI-0000JE-6e for guix-devel@gnu.org; Sun, 12 Aug 2018 20:28:05 -0400 Received: from dustycloud.org ([50.116.34.160]:52188) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fp0iI-0000J4-1K for guix-devel@gnu.org; Sun, 12 Aug 2018 20:28:02 -0400 In-reply-to: <87k1ovbc0t.fsf@ngyro.com> List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org Sender: "Guix-devel" To: Timothy Sample Cc: guix-devel@gnu.org Timothy Sample writes: > Hi Guix, > > I just submitted a patch for , but now I=E2= =80=99m > wondering if there isn=E2=80=99t a more general way to solve the problem. > > The bug has to do with grafting and checksums. I know three bugs that > follow this theme: the one above (Racket), > (GDB), and (Go). The basic problem is that > these packages store checksums of files during build time. If they get > updated due to grafting, the files change, but the checksums do not. > The checksums become invalid, which causes other problems like trying to > update files in the store or asserting that debugging information is > invalid. > > The patch I submitted makes Racket assume that files in the store are > good. It patches Racket to skip checksum validation if it is checking a > file in the store. A similar approach could be taken for GDB and Go. > > It occurs to me that if we had some way to run package-specific code > during grafting we could solve problems like this easily and without > patching software that is not broken. > > The basic idea would be to add a field (or use a property) to the > package record. Let=E2=80=99s call it =E2=80=9Cgraft-hook=E2=80=9D. It = would be Scheme code > that gets run after grafting takes place, giving us a chance to patch > special things like checksums. The hook would be passed the list of > files that were been modified during grafting. Then, in the Racket > package for example, I could write a graft-hook that updates the SHA-1 > hash of each of the modified source files. This seems like a really good approach to me and seems also much nicer / safer in the long run than the solution in #30680 since it wouldn't just patch out the package in question's checks, it would correct them. That seems very good indeed to me. > Since grafting is done at the derivation level, the hook code would have > to be propagated down from the package level. I haven=E2=80=99t looked a= t all > the details yet, because maybe this is a bad idea and I shouldn=E2=80=99t= waste > my time! :) My first impression is that it is not too tricky. > > Are these problems too specialized to deserve a general mechanism like > this? Let me know what you think! > > > -- Tim As said, it seems good to me. But I would be interested in what Mark would think, since he is mostly responsible for the grafts design.