#include <unistd.h>
#include <signal.h>

static void sig_alrm(int signo) {

}

unsigned int sleep(unsigned int seconds) {
  struct sigaction newact, oldact;
  sigset_t newmask, oldmask, suspmask;
  unsigned int unslept;

  newact.sa_handler = sig_alrm;
  sigemptyset(&newact.sa_mask);
  newact.sa_flags = 0;
  sigaction(SIGALRM, &newact, &oldact);

  sigemptyset(&newmask);
  sigaddset(&newmask, SIGALRM);
  sigprocmask(SIG_BLOCK, &newmask, &oldmask);

  alarm(seconds);
  suspmask = oldmask;

  sigdelset(&suspmask, SIGALRM);
  sigsuspend(&suspmask);
  unslept = alarm(0);
  
  sigaction(SIGALRM, &oldact, NULL);

  sigprocmask(SIG_SETMASK, &oldmask, NULL);
  return unslept;

}

int main(void) {
  return sleep(5);
}