cp -pr --reflink=auto -- /nix/store/dl6ahdcycmw4yry2zpmslq7w7i2mdlvk-source source
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }', src/uu/cp/src/cp.rs:1257:10
stack backtrace:
   0: rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::result::unwrap_failed
   3: uu_cp::copy_helper
   4: uu_cp::copy_file
   5: uu_cp::copy
   6: uu_cp::uumain
   7: coreutils::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

result/bin/uutils-cp -r --reflink=auto /nix/store/dvh1x2m7gvp1iv5jjlvrf5ry5g3ay23k-source source
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 13, kind: PermissionDenied, message: "Permission denied" }', src/uu/cp/src/cp.rs:1257:10
stack backtrace:
   0:     0x626c2f3f510c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h579b28686b409bee
   1:     0x626c2f41f10f - core::fmt::write::h177edd21b8369127
   2:     0x626c2f3f4666 - std::io::Write::write_fmt::haa2ae72671ba5de2
   3:     0x626c2f3d4a85 - std::panicking::default_hook::{{closure}}::h71a46c54ea32ce02
   4:     0x626c2f3d4653 - std::panicking::default_hook::h562e9028aa910d56
   5:     0x626c2f3d50ea - std::panicking::rust_panic_with_hook::hb6c7abba650d43fa
   6:     0x626c2f3f5597 - std::panicking::begin_panic_handler::{{closure}}::h477cfd41c4af51c1
   7:     0x626c2f3f524c - std::sys_common::backtrace::__rust_end_short_backtrace::h2441af18d2e25caa
   8:     0x626c2f3d4c62 - rust_begin_unwind
   9:     0x626c2f422381 - core::panicking::panic_fmt::h517c1ed6f8518cd6
  10:     0x626c2f427953 - core::result::unwrap_failed::h441cbb6e6d50fbfd
  11:     0x626c2f32a62e - uu_cp::copy_helper::h0d6f49dd6ece054a
  12:     0x626c2f327b35 - uu_cp::copy_file::h61df3196d7a7b976
  13:     0x626c2f325c32 - uu_cp::copy::h8f71f7611c902b71
  14:     0x626c2f01006a - uu_cp::uumain::h95ac159c93136cc4
  15:     0x626c2efe15e0 - coreutils::main::h034f826d5af37e42
  16:     0x626c2efdc2d3 - std::sys_common::backtrace::__rust_begin_short_backtrace::h612ef4d5ed08f219
  17:     0x626c2f084ac9 - std::rt::lang_start::{{closure}}::h9f84df5707532228
  18:     0x626c2f3d547a - std::rt::lang_start_internal::h8fef16c8ee038552
  19:     0x626c2efe1862 - main
  20:     0x71921ff86ded - __libc_start_main
  21:     0x626c2efb41ea - _start
  22:                0x0 - <unknown>

sudo tar --same-owner --preserve-permissions -xf source.tar.gz
sudo chmod 400 nix -R
sudo chown root:root nix -R
uutils-cp -r --reflink=auto nix/store/dvh1x2m7gvp1iv5jjlvrf5ry5g3ay23k-source source