Ever wish your life was more full of tarballs? Especially in your Nix store? We have the solution for you! Introducing, tarnix!
Tarnix is the only solution to the problem, and works on the most
modern versions of both Lix and Nix! No more fussing about with
input-addressed builtin:fetchurl being patched, this solution will
stand the test of time.
..Okay, but like. This exists because of a lack of a primitive in Nix, and this is a terrifying workaround for it:
Text paths that reference non-text paths.
nix-repl> builtins.toFile "test" "hi ${pkgs.hello}"
error:
… while calling the 'toFile' builtin
at «string»:1:1:
1| builtins.toFile "test" "hi ${pkgs.hello}"
| ^
error: files created by builtins.toFile may not reference derivations, but test references !out!af3rc6phyv80h7aq4y3d08awnq2ja8fp-hello-2.12.1.drv
To fix this, nixpkgs has writeTextFile. But this is a massive hammer,
and I don't want to use nixpkgs when not necessary. So, instead, I
decided to grab that massive hammer and point it directly at Nix
itself.
After a while, we figured out a solution that was reasonable, but had
its limits: Generating a NAR file, and then using an input-addressed
builtin:fetchurl derivation. However, this was broken unceremoniously
by CppNix, due to an apparent "vulnerability", which was actually a bug
in the Nix sandbox on macOS, which was fixed 8.5 months after the Nix
team was made aware of it in February.
In my search for a modern alternative, I found out about
builtin:unpack-channel. It uses libarchive to unpack archives at
build time, which means it can reference the outputs of derivations!
So, what one can do, is ....
nix-repl> :b let tar = builtins.toFile "a" (lib.makeTar [(lib.dir "meow") (lib.file "meow/uwu" false "hi!\n")]);
in derivation { name = "a"; system = "a"; builder = "builtin:unpack-channel"; src = "${tar}"; channelName = "meow"; }
This derivation produced the following outputs:
out -> /nix/store/vpx98lid40kd4k18ksrpzcqsvdblhdhk-a
puckipedia@marisa ~/tarnix> cat /nix/store/vpx98lid40kd4k18ksrpzcqsvdblhdhk-a/meow/uwu
hi!
..now, this isn't the full extent of our crimes (a good magician
witch keeps some spare tricks up her sleeves~), but they're out there :3