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: rtcwake.rs
    path of file: ./repos/rustybox/util_linux
    
    the code of the file until where you have to start completion: use libc;
use libc::printf;
use libc::ssize_t;
use libc::strcmp;
use libc::sync;
use libc::time;
use libc::time_t;
use libc::tm;
use libc::useconds_t;
extern "C" {

  #[no_mangle]
  fn snprintf(
    _: *mut libc::c_char,
    _: libc::c_ulong,
    _: *const libc::c_char,
    _: ...
  ) -> libc::c_int;
  #[no_mangle]
  fn usleep(__useconds: useconds_t) -> libc::c_int;

  #[no_mangle]
  fn localtime(__timer: *const time_t) -> *mut tm;
  #[no_mangle]
  fn ctime(__timer: *const time_t) -> *mut libc::c_char;

/*
 * Common defines/structures/etc... for applets that need to work with the RTC.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

}

/*
 * Everything below this point has been copied from linux/rtc.h
 * to eliminate the kernel header dependency
 */

#[repr(C)]
#[derive(Copy, Clone)]
pub struct linux_rtc_time {
  pub tm_sec: libc::c_int,
  pub tm_min: libc::c_int,
  pub tm_hour: libc::c_int,
  pub tm_mday: libc::c_int,
  pub tm_mon: libc::c_int,
  pub tm_year: libc::c_int,
  pub tm_wday: libc::c_int,
  pub tm_yday: libc::c_int,
  pub tm_isdst: libc::c_int,
}

#[repr(C)]
#[derive(Copy, Clone)]
pub struct linux_rtc_wkalrm {
    
unsafe fn setup_alarm(mut fd: libc::c_int, mut wakeup: *mut time_t, mut rtc_time: time_t) {
  let mut ptm: *mut tm = std::ptr::null_mut();
  let mut wake: linux_rtc_wkalrm = linux_rtc_wkalrm {
    enabled: 0,
    pending: 0,
    time: linux_rtc_time {
      tm_sec: 0,
      tm_min: 0,
      tm_hour: 0,
      tm_mday: 0,
      tm_mon: 0,
      tm_year: 0,
      tm_wday: 0,
      tm_yday: 0,
      tm_isdst: 0,
    },
  };
  /* The wakeup time is in POSIX time (more or less UTC).
   * Ideally RTCs use that same time; but PCs can't do that
   * if they need to boot MS-Windows.  Messy...
   *
   * When running in utc mode this process's timezone is UTC,
   * so we'll pass a UTC date to the RTC.
   *
   * Else mode is local so the time given to the RTC
   * will instead use the local time zone.
   */
  ptm = localtime(wakeup);
  wake.time.tm_sec = (*ptm).tm_sec;
  wake.time.tm_min = (*ptm).tm_min;
  wake.time.tm_hour = (*ptm).tm_hour;
  wake.time.tm_mday = (*ptm).tm_mday;
  wake.time.tm_mon = (*ptm).tm_mon;
  wake.time.tm_year = (*ptm).tm_year;
  /* wday, yday, and isdst fields are unused by Linux */
  wake.time.tm_wday = -1i32;
  wake.time.tm_yday = -1i32;
  wake.time.tm_isdst = -1i32;
  /* many rtc alarms only support up to 24 hours from 'now',
   * so use the "more than 24 hours" request only if we must
   */
  if rtc_time + (24i32 * 60i32 * 60i32) as libc::c_long > *wakeup {
    crate::libbb::xfuncs_printf::bb_xioctl(
      fd,
      ((1u32 << 0 + 8i32 + 8i32 + 14i32
        | (('p' as i32) << 0 + 8i32) as libc::c_uint
        | (0x7i32 << 0) as libc::c_uint) as libc::c_ulong
        | (::std::mem::size_of::<linux_rtc_time>() as libc::c_ulong) << 0 + 8i32 + 8i32)
        as libc::c_uint,
      &mut wake.time as *mut linux_rtc_time as *mut libc::c_void,
      b"RTC_ALM_SET\x00" as *const u8 as *const libc::c_char,
    );
    crate::libbb::xfuncs_printf::bb_xioctl(
      fd,
      0u32 << 0 + 8i32 + 8i32 + 14i32
        | (('p' as i32) << 0 + 8i32) as libc::c_uint
        | (0x1i32 << 0) as libc::c_uint
        | (0i32 << 0 + 8i32 + 8i32) as libc::c_uint,
      0 as *mut libc::c_void,
      b"RTC_AIE_ON\x00" as *const u8 as *const libc::c_char,
    );
  } else {
    /* avoid an extra AIE_ON call */
    wake.enabled = 1i32 as libc::c_uchar; /* for compiler */
    crate::libbb::xfuncs_printf::bb_xioctl(
      fd,
      ((1u32 << 0 + 8i32 + 8i32 + 14i32
        | (('p' as i32) << 0 + 8i32) as libc::c_uint
        | (0xfi32 << 0) as libc::c_uint) as libc::c_ulong
        | (::std::mem::size_of::<linux_rtc_wkalrm>() as libc::c_ulong) << 0 + 8i32 + 8i32)
        as libc::c_uint,
      &mut wake as *mut linux_rtc_wkalrm as *mut libc::c_void,
      b"RTC_WKALM_SET\x00" as *const u8 as *const libc::c_char,
    );
  };
}