Function nc::copy_file_range

pub fn copy_file_range(
    fd_in: i32, 
    off_in: &mut loff_t, 
    fd_out: i32, 
    off_out: &mut loff_t, 
    len: size_t, 
    flags: u32
) -> Result<ssize_t, Errno>

Copy a range of data from one file to another.

let path_in = "/etc/passwd";
let fd_in = nc::openat(nc::AT_FDCWD, path_in, nc::O_RDONLY, 0);
assert!(fd_in.is_ok());
let fd_in = fd_in.unwrap();
let path_out = "/tmp/nc-copy-file-range";
let fd_out = nc::openat(nc::AT_FDCWD, path_out, nc::O_WRONLY | nc::O_CREAT, 0o644);
assert!(fd_out.is_ok());
let fd_out = fd_out.unwrap();
let mut off_in = 0;
let mut off_out = 0;
let copy_len = 64;
let ret = nc::copy_file_range(fd_in, &mut off_in, fd_out, &mut off_out, copy_len, 0);
assert!(ret.is_ok());
assert_eq!(ret, Ok(copy_len as nc::ssize_t));
assert!(nc::close(fd_in).is_ok());
assert!(nc::close(fd_out).is_ok());
assert!(nc::unlinkat(nc::AT_FDCWD, path_out, 0).is_ok());