Function posish::fs::copy_file_range

pub fn copy_file_range<InRawFd: AsRawFd, OutRawFd: AsRawFd>(
    fd_in: &InRawFd, 
    off_in: Option<&mut u64>, 
    fd_out: &OutRawFd, 
    off_out: Option<&mut u64>, 
    len: u64
) -> Result<u64>

copy_file_range(fd_in, off_in, fd_out, off_out, len, 0)