// Don't bail on the first error, but remember the worst one.
let mut worst = 0;
for file in files {
    if let Err(e) = chmod_one(file) {
        worst = worst.max(e.exit_code());
    }
}
process::exit(worst);

This is not rustic, I feel.

files.iter()
  .map(chmod_one)
  .filter_map(Result::err)

is more like it.

From there, you can next() for first error, last() for last error, or fold() for max error, or collect() if you need to save all errors.

And no, static compilation doesn’t help here, because get_user_by_name goes through NSS, which dlopens libnss_* modules at runtime regardless of whether your binary is statically linked.

This is not true in musl systems. I just quickly checked in a Chimera rootfs (which has a system dynamic musl libc btw).

I believe the described dlopening is one of the well known reasons why GNU libc is not suitable for static linking, unlike musl!

In Arch, this indeed loads /usr/lib/libnss_systemd.so.2.

Everyone can test this with strace id 2>&1 | egrep 'open.*\.so'.