cp: inconvenient err message at echo 1|cp /dev/stdin /dev/full

[oech3]

$ echo 1 | uu-cp /dev/stdin /dev/full
cp: '/dev/stdin' -> '/dev/full': other error
$ echo 1 | gnu-cp /dev/stdin /dev/full
cp: error writing '/dev/full': No space left on device

while uu-cp /etc/pacman.conf /dev/full has convenient message.

[max-amb]

Ok, so I have tried to work on this but I am a bit lost, so hopefully someone else can advise/continue.
The pattern matching could be done at line 253 of src/platform/linux.rs:

    let num_bytes_copied = buf_copy::copy_stream(&mut src_file, &mut dst_file)
        .map_err(|_| std::io::Error::from(std::io::ErrorKind::Other))?;

copy_stream returns a UResult<64> meaning the error is of the form Box<dyn UError + 'static>:

[src/uu/cp/src/platform/linux.rs:254:24] e = UIoError {
    context: None,
    inner: Os {
        code: 28,
        kind: StorageFull,
        message: "No space left on device",
    },
}

I am not sure how to get the data out to pattern match, probably due to inexperience with rust.
If it is urgent a very hacky fix could be in buf_copy/linux.rs line 138 in copy_exact where we could pattern match to nix::errno::Errno::ENOSPC and panic (or anywhere else up the stack).

Anyway, hope this helps someone or someone can help me 😃