You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: sync.rs
    path of file: ./repos/rustybox/coreutils
    
    the code of the file until where you have to start completion: use libc;
use libc::close;
use libc::sync;
extern "C" {
  #[no_mangle]
  static mut optind: libc::c_int;
  #[no_mangle]
  fn fsync(__fd: libc::c_int) -> libc::c_int
    
pub unsafe fn sync_main(mut _argc: libc::c_int, mut argv: *mut *mut libc::c_char) -> libc::c_int {
  let mut opts: libc::c_uint = crate::libbb::getopt32::getopt32(
    argv,
    b"^df\x00d--f:f--d\x00" as *const u8 as *const libc::c_char,
  );
  argv = argv.offset(optind as isize);
  if (*argv.offset(0)).is_null() {
    sync();
    return 0;
  }
  return sync_common(opts as libc::c_int, argv);
}