tests/setitimer.c

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#include "test_skel.h"

int main(int argc, char *argv[]) {
  // We need an invalid timer value. The assert()'s below should
  // be static asserts but it is not avalible in older C versions.
#define kInvalidTimer 9999
  assert(kInvalidTimer != ITIMER_REAL);
  assert(kInvalidTimer != ITIMER_VIRTUAL);
  assert(kInvalidTimer != ITIMER_PROF);

  // Invalid timer returns EINVAL.
  assert(sys_setitimer(kInvalidTimer, NULL, NULL) == -1);
  assert(errno == EINVAL);

  const int kSignal = SIGALRM;
  const size_t kSigsetSize = sizeof(struct kernel_sigset_t);

  // Block SIGALRM.
  struct kernel_sigset_t sigalarm_only;
  struct kernel_sigset_t old_sigset;
  assert(sys_sigemptyset(&sigalarm_only) == 0);
  assert(sys_sigaddset(&sigalarm_only, kSignal) == 0);
  assert(sys_rt_sigprocmask(SIG_BLOCK, &sigalarm_only, &old_sigset,
                            kSigsetSize) == 0);

  // Set up a real time timer.
  struct kernel_itimerval new_itimer = {};
  const long kIntervalUSec = 123;
  new_itimer.it_interval.tv_sec = 0;
  new_itimer.it_interval.tv_usec = kIntervalUSec;
  new_itimer.it_value = new_itimer.it_interval;
  assert(sys_setitimer(ITIMER_REAL, &new_itimer, NULL) == 0);

  // Wait for alarm.
  struct timespec timeout;
  const unsigned long kNanoSecsPerSec = 1000000000;
  const unsigned long kNanoSecsPerMicroSec = 1000;

  // Use a timeout 3 times of the timer interval.
  unsigned long duration_ns = kIntervalUSec * kNanoSecsPerMicroSec * 3;
  timeout.tv_sec = duration_ns / kNanoSecsPerSec ;
  timeout.tv_nsec = duration_ns % kNanoSecsPerSec;

  int sig;
  do {
    sig = sys_sigtimedwait(&sigalarm_only, NULL, &timeout);
  } while (sig == -1 && errno == EINTR);
  assert(sig == kSignal);

  // Disable timer, check saving of old timer value.
  struct kernel_itimerval empty_itimer = {};
  struct kernel_itimerval old_itimer;
  empty_itimer.it_interval.tv_sec = 0;
  empty_itimer.it_interval.tv_usec = 0;
  empty_itimer.it_value = empty_itimer.it_interval;

  assert(sys_setitimer(ITIMER_REAL, &empty_itimer, &old_itimer) == 0);
  assert(kernel_timeval_eq(&old_itimer.it_interval, &new_itimer.it_interval));

  return 0;
}