vulkan-cts: --deqp-vk-library-path=... unreliable (sensitive to LD_LIBRARY_PATH).

[eddyb]

Describe the bug

The deqp-vk executable of the vulkan-cts package is pretty much guaranteed to not work if LD_LIBRARY_PATH is set (and doesn't include vulkan-loader specifically).

Steps To Reproduce

Steps to reproduce the behavior:

$ cd $(mktemp -d) && LD_LIBRARY_PATH= nix-shell -p vulkan-cts --run deqp-vk
Writing test log into TestResults.qpa
dEQP Core unknown (0xcafebabe) starting..
  target implementation = 'Default'
FATAL ERROR: Failed to open dynamic library: '/nix/store/fr89g4mi5zsplmjfl56y0ckl7pzzdskq-vulkan-loader-1.3.283.0/lib/libvulkan.so'
/tmp/nix-shell-1315847-0/rc: line 3: 1319655 Killed                  deqp-vk

(as per KhronosGroup/VK-GL-CTS#479, it actually tries dlopen("libvulkan.so") - more precisely, dlopen(basename("/nix/store/.../libvulkan.so")), throwing away absolute paths)

Expected behavior

deqp-vk should work regardless of the ambient value of LD_LIBRARY_PATH.

Additional context

I've filed an upstream report for the bizarre sensitivity to LD_LIBRARY_PATH:

• deDynamicLibrary_open intentionally(?) truncates its argument when LD_LIBRARY_PATH is set. KhronosGroup/VK-GL-CTS#479

Might make sense to patch it in nixpkgs than trying to work around it by e.g. appending ${vulkan-loader}/lib to LD_LIBRARY_PATH etc. (even if that might be easier for now - locally I just unset LD_LIBRARY_PATH before running deqp-vk).

Notify maintainers

cc @Flakebi

Metadata

$ nix-shell -p nix-info --run "nix-info -m"
 - system: `"x86_64-linux"`
 - host os: `Linux 6.8.12, NixOS, 24.11 (Vicuna), 24.11pre662544.cb9a96f23c49`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Lix, like Nix) 2.90.0`
 - channels(root): `"nixos"`
 - nixpkgs: `/nix/var/nix/profiles/per-user/root/channels/nixos`

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