Function copy_len_with_progress

pub fn copy_len_with_progress<R, W, P>(
    read: R,
    write: W,
    buf: &mut [u8],
    len: u64,
    progress: P,
) -> Result<u64, CopyError<R::Error, W::Error>>
where
    R: Read,
    W: Write,
    P: Fn(u64, u64),