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"); } }