So it sounds like you don’t get the exact version you want because metadata is thrown away.
replyIt's a checksum not the content itself
replyYeah, Nix-like distributions (e.g. guix, lix) do for Linux systems what some language package managers (e.g. cargo) do for individual projects.
replyAre the xattr / chattr / umask checksums rolled into the main data fork content or are they hashed separately (or not at all)?
replyIIRC Nix is checksummed in the hash of the source of the content, not the results.
replyHash of a normalization of the derivation, so this roughly means source, dependencies and the ‘build recipe’. The exception are fixed-output derivations, which are typically content-hashed.
replyThat said, a lot of work is done in content-addressed hashing, but AFAIK it’s not the default yet.