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use nix::sys::signal::{
sigaction, SaFlags, SigAction, SigEvent, SigHandler, SigSet, SigevNotify,
Signal,
};
use nix::sys::timer::{Expiration, Timer, TimerSetTimeFlags};
use nix::time::ClockId;
use std::convert::TryFrom;
use std::sync::atomic::{AtomicBool, Ordering};
use std::thread;
use std::time::{Duration, Instant};
const SIG: Signal = Signal::SIGALRM;
static ALARM_CALLED: AtomicBool = AtomicBool::new(false);
pub extern "C" fn handle_sigalarm(raw_signal: libc::c_int) {
let signal = Signal::try_from(raw_signal).unwrap();
if signal == SIG {
ALARM_CALLED.store(true, Ordering::Release);
}
}
#[test]
fn alarm_fires() {
// Avoid interfering with other signal using tests by taking a mutex shared
// among other tests in this crate.
let _m = crate::SIGNAL_MTX.lock();
const TIMER_PERIOD: Duration = Duration::from_millis(100);
//
// Setup
//
// Create a handler for the test signal, `SIG`. The handler is responsible
// for flipping `ALARM_CALLED`.
let handler = SigHandler::Handler(handle_sigalarm);
let signal_action =
SigAction::new(handler, SaFlags::SA_RESTART, SigSet::empty());
let old_handler = unsafe {
sigaction(SIG, &signal_action)
.expect("unable to set signal handler for alarm")
};
// Create the timer. We use the monotonic clock here, though any would do
// really. The timer is set to fire every 250 milliseconds with no delay for
// the initial firing.
let clockid = ClockId::CLOCK_MONOTONIC;
let sigevent = SigEvent::new(SigevNotify::SigevSignal {
signal: SIG,
si_value: 0,
});
let mut timer =
Timer::new(clockid, sigevent).expect("failed to create timer");
let expiration = Expiration::Interval(TIMER_PERIOD.into());
let flags = TimerSetTimeFlags::empty();
timer.set(expiration, flags).expect("could not set timer");
//
// Test
//
// Determine that there's still an expiration tracked by the
// timer. Depending on when this runs either an `Expiration::Interval` or
// `Expiration::IntervalDelayed` will be present. That is, if the timer has
// not fired yet we'll get our original `expiration`, else the one that
// represents a delay to the next expiration. We're only interested in the
// timer still being extant.
match timer.get() {
Ok(Some(exp)) => assert!(matches!(
exp,
Expiration::Interval(..) | Expiration::IntervalDelayed(..)
)),
_ => panic!("timer lost its expiration"),
}
// Wait for 2 firings of the alarm before checking that it has fired and
// been handled at least the once. If we wait for 3 seconds and the handler
// is never called something has gone sideways and the test fails.
let starttime = Instant::now();
loop {
thread::sleep(2 * TIMER_PERIOD);
if ALARM_CALLED.load(Ordering::Acquire) {
break;
}
if starttime.elapsed() > Duration::from_secs(3) {
panic!("Timeout waiting for SIGALRM");
}
}
// Cleanup:
// 1) deregister the OS's timer.
// 2) Wait for a full timer period, since POSIX does not require that
// disabling the timer will clear pending signals, and on NetBSD at least
// it does not.
// 2) Replace the old signal handler now that we've completed the test. If
// the test fails this process panics, so the fact we might not get here
// is okay.
drop(timer);
thread::sleep(TIMER_PERIOD);
unsafe {
sigaction(SIG, &old_handler).expect("unable to reset signal handler");
}
}