// By convention, anything in the bin/ directory of the package is a
        // binary. This is done for some old dists missing the X bits in those dirs
        let is_bin = if let Some(p) = full_path.parent() {
            // An optimisation for efficiency would be to detect this in the
            // components iteration rather than re-calculating path parent() here.
            p.ends_with("bin")
        } else {
            false
        };
        // Directories and any files marked X and anything shipped in bin keep the X bit.
        let needs_x = is_dir || tar_mode & 0o100 == 0o100 || is_bin;
        let mode = if needs_x { 0o755 } else { 0o644 };