Nix 2.27.0 released

elikoga · March 21, 2025, 6:49pm

https://github.com/NixOS/nix/issue/11503
https://github.com/NixOS/nix/issue/12443

should be

github.com/NixOS/nix

`builtins.path` and `builtins.filterSource` use wrong filter paths with `--store` argument

opened 05:30PM - 15 Sep 24 UTC

closed 12:47AM - 20 Feb 25 UTC

Yarny0

bug

**Describe the bug** The built-in functions `builtins.path` or `builtins.filt…erSource` both accept a root path and a filter function. The filter function is then called with subpaths of the root path as argument. Under certain circumstances, those subpaths are in fact *not* subpaths of the root path. As far as I could investigate, this happens if * the `--store` argument is used to point to another store that is not the "canonical" store ("canonical" usually is `/nix/store`), * the nix file that is evaluate and that contains the call to a built-in function is itself positioned in the "canonical" nix store, * the root directory points to `./.`, and * the derivation that contains the nix file is also present in the other nix store. Note that these circumstances are usually given when you install NixOS from a live iso with `nixos-install`: Most nix files involved are contained in the `nixos` channel, which is somewhere in `/nix/store`. This channel is copied to `/mnt/nix/store` by `nixos-install` before anything else is done. **Steps To Reproduce** Put these two files in the same directory, then execute `test.sh` (this expects Nix to be installed and accessible, but no root privileges): <details> <summary><code>test.nix</code></summary> ```nix let root = ./.; filter = path: type: let rootStr = builtins.toString ./.; in if builtins.substring 0 (builtins.stringLength rootStr) (builtins.toString path) == rootStr then true else builtins.throw "root path\n${rootStr}\nnot prefix of path\n${builtins.toString path}"; in # each one will demonstrate the problem!: #builtins.path { name="name"; path=root; inherit filter; } builtins.filterSource filter root ``` </details> <details> <summary><code>test.sh</code></summary> ```shell #! /usr/bin/env bash tmpdir=$(mktemp -d) mkdir $tmpdir/directory cp test.nix $tmpdir/directory/default.nix result=$(nix-store --add-fixed --recursive sha256 $tmpdir/directory) nix-instantiate --eval $result nix-instantiate --eval $result --store $tmpdir/2nd-store nix-store --add-fixed --recursive sha256 $tmpdir/directory --store $tmpdir/2nd-store echo this will fail... nix-instantiate --eval $result --store $tmpdir/2nd-store ``` </details> The final `nix-instantiate` will trigger the `throw` from `text.nix` -- apparently `filterSource` confuses the store paths: ``` error: root path /nix/store/dv15ix385vx19wxac0v5h5n7x8i5iwgp-directory not prefix of path /tmp/tmp.f3xsGxSb42/2nd-store/nix/store/dv15ix385vx19wxac0v5h5n7x8i5iwgp-directory/default.nix ``` **Expected behavior** The final `nix-instantiate` invocation should succeed. **`nix-env --version` output** nix-env (Nix) 2.18.5 **Additional context** Nixpkgs contains many instances of `src = lib.fileset.toSouce { root = ./.; fileset = ..something..; }` which are liable to trigger this bug if evaluated from within `nixos-install`; in that case `src` ends up as empty directory because the filter function from the fileset library constantly returns `false`. One such instance is documented (with steps to reproduce with `nixos-install`) in https://github.com/NixOS/nixpkgs/issues/334098 . **Priorities** Add :+1: to [issues you find important](https://github.com/NixOS/nix/issues?q=is%3Aissue+is%3Aopen+sort%3Areactions-%2B1-desc).

github.com/NixOS/nix

nix flake prefetch: Add --out-link option

NixOS:master ← DeterminateSystems:prefetch-out-link

opened 04:54PM - 10 Feb 25 UTC

edolstra

+30 -8

## Motivation This makes `nix flake prefetch` more useful for scripting and prevents the result from being GC'ed prematurely. ## Context --- Add :+1: to [pull requests you find important](https://github.com/NixOS/nix/pulls?q=is%3Aopen+sort%3Areactions-%2B1-desc). The Nix maintainer team uses a [GitHub project board](https://github.com/orgs/NixOS/projects/19) to [schedule and track reviews](https://github.com/NixOS/nix/tree/master/maintainers#project-board-protocol).

I believe? The link is broken due to linking to github issue rather than pull