{
  closureInfo, runCommand,
  e2fsprogs,
  pigeon-disc-size ? "1G",
  pigeon-toolchain,
  pigeon-init,
  pigeon-run
}:

let
  closure = closureInfo { rootPaths = [ pigeon-toolchain ]; };
in
  runCommand "pigeon-rootfs" { nativeBuildInputs = [ e2fsprogs ]; } ''
    mkdir -p rootfs && cd rootfs
    mkdir -p dev proc sys tmp usr nix/store root/student root/grader root/results
    chmod 700 root

    for FILE in $(cat ${closure}/store-paths); do
      cp -a "$FILE" nix/store
    done
    ln -s ${pigeon-toolchain}/bin bin
    ln -s ${pigeon-toolchain}/bin usr/bin
    install -m 755 ${pigeon-init}/bin/pigeon-init init
    install -m 755 ${pigeon-run}/bin/pigeon-run run

    cd ..
    mkfs.ext4 -q -F -d rootfs $out ${pigeon-disc-size}
  ''