fetchTarball fails after downloading proton-ge

[babbaj]

Describe the bug

In my config I've been using fetchTarball to download proton-ge builds but after updating to nix 2.21.0 I am now getting this error from fetchTarball error: adding a file to a tree builder: failed to insert entry: invalid name for a tree entry - .git

Steps To Reproduce

run nix repl --expr 'fetchTarball { url = "https://github.com/GloriousEggroll/proton-ge-custom/releases/download/GE-Proton9-4/GE-Proton9-4.tar.gz"; sha256 = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA="; }' (older versions have the same problem)

Expected behavior

fetchTarball should be able to unpack the tar file with no errors

nix-env --version output

babbaj@nixos:~ ❯ nix --version
nix (Nix) 2.21.0

Additional context

There is a .git folder included in the protonfixes subdirectory which is probably what is triggering the error. I believe the error comes specifically from here https://github.com/NixOS/nix/blob/8c4c2156bd786156a57219e78aa14a363ca8f041/src/libfetchers/git-utils.cc#L820 It doesn't make sense to me why git is involved in fetchTarball when it should and seemingly has been able to unpack any abitrary files in stable releases.

This commit is most likely what introduced this regression. https://github.com/NixOS/nix/commit/cabee9815239af426cece729cb765810b8a716ce

proton-ge was also added to nixpkgs recently and uses fetchzip instead of fetchTarball. Using fetchzip in place of fetchTarball works fine.

Priorities

Add :+1: to issues you find important.

[thufschmitt]

cc @edolstra . I can confirm this, and https://github.com/NixOS/nix/commit/cabee9815239af426cece729cb765810b8a716ce is a very likely culprit indeed. If we want to keep this git hashing thing, we'll need to be able to bail out of work around this kind of file names that aren't accepted by libgit2

[pluiedev]

Evidently this is not limited to fetchTarball... fetchTree also fails, triggered by call-flake.nix:

… in the condition of the assert statement
         at «nix-internal»/call-flake.nix:79:13:
           78|           if node.flake or true then
           79|             assert builtins.isFunction flake.outputs;
             |             ^
           80|             result

       … while calling the 'isFunction' builtin
         at «nix-internal»/call-flake.nix:79:20:
           78|           if node.flake or true then
           79|             assert builtins.isFunction flake.outputs;
             |                    ^
           80|             result

       … while calling the 'import' builtin
         at «nix-internal»/call-flake.nix:54:19:
           53|
           54|           flake = import (outPath + "/flake.nix");
             |                   ^
           55|

       … while realising the context of a path

       … while calling the 'fetchTree' builtin
         at «nix-internal»/call-flake.nix:48:15:
           47|               # FIXME: remove obsolete node.info.
           48|               fetchTree (node.info or {} // removeAttrs node.locked ["dir"]);
             |               ^
           49|

       … while fetching the input 'github:ipetkov/crane/529c1a0b1f29f0d78fa3086b8f6a134c71ef3aaf?narHash=sha256-k3oiD2z2AAwBFLa4%2BxfU%2B7G5fisRXfkvrMTCJrjZzXo%3D'

       error: adding a file to a tree builder: failed to insert entry: invalid object specified - test.yml ```

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/need-help-with-this-git-related-flake-update-error/50538/7