1 files changed, 91 insertions, 0 deletions
diff --git a/test/test_timer.rs b/test/test_timer.rs
new file mode 100644
index 00000000..31a740b0
--- /dev/null
+++ b/test/test_timer.rs
@@ -0,0 +1,91 @@
+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();
+
+    //
+    // 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(Duration::from_millis(250).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(Duration::from_millis(500));
+        if ALARM_CALLED.load(Ordering::Acquire) {
+            break;
+        }
+        if starttime.elapsed() > Duration::from_secs(3) {
+            panic!("Timeout waiting for SIGALRM");
+        }
+    }
+
+    // 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.
+    unsafe {
+        sigaction(SIG, &old_handler).expect("unable to reset signal handler");
+    }
+}