Merge pull request #255224 from Artturin/copybtrfsimp

, lib

# List of derivations to be included

, storePaths

# Whether or not to compress the resulting image with zstd

, compressImage ? false, zstd

# Shell commands to populate the ./files directory.

# All files in that directory are copied to the root of the FS.

, populateImageCommands ? ""

  sdClosureInfo = pkgs.buildPackages.closureInfo { rootPaths = storePaths; };

in

pkgs.stdenv.mkDerivation {

  name = "btrfs-fs.img";

  name = "btrfs-fs.img${lib.optionalString compressImage ".zst"}";

  nativeBuildInputs = [ btrfs-progs ];

  nativeBuildInputs = [ btrfs-progs ] ++ lib.optional compressImage zstd;

  buildCommand =

    ''

      ${if compressImage then "img=temp.img" else "img=$out"}

      set -x

      (

          mkdir -p ./files

          ${populateImageCommands}

      )

      mkdir -p ./files/nix/store

      cp ${sdClosureInfo}/registration ./files/nix-path-registration

      mkdir -p ./rootImage/nix/store

      xargs -I % cp -a --reflink=auto % -t ./rootImage/nix/store/ < ${sdClosureInfo}/store-paths

      (

        GLOBIGNORE=".:.."

        shopt -u dotglob

      # Add the closures of the top-level store objects.

      for p in $(cat ${sdClosureInfo}/store-paths); do

        echo cp -r $p "./files/nix/store"

        for f in ./files/*; do

            cp -a --reflink=auto -t ./rootImage/ "$f"

        done

      )

      cp ${sdClosureInfo}/registration ./rootImage/nix-path-registration

      touch $img

      mkfs.btrfs -L ${volumeLabel} -U ${uuid} -r ./rootImage --shrink $img

      if ! btrfs check $img; then

        echo "--- 'btrfs check' failed for BTRFS image ---"

        return 1

      fi

      touch $out

      mkfs.btrfs -L ${volumeLabel} -U ${uuid} -r ./files --shrink $out

      if [ ${builtins.toString compressImage} ]; then

        echo "Compressing image"

        zstd -v --no-progress ./$img -o $out

      fi

    '';

}