Timothy Sample writes: > Hi Guix, > > I just submitted a patch for <https://bugs.gnu.org/30680>, but now I’m > wondering if there isn’t 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), <https://bugs.gnu.org/19973> > (GDB), and <https://bugs.gnu.org/25752> (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’s call it “graft-hook”. 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’t looked at all > the details yet, because maybe this is a bad idea and I shouldn’t 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.
