test.c

#include <pthread.h>
#include <semaphore.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>

static void* worker(void* arg) {
  int ret = sem_post((sem_t*) arg);
  if (ret == -1) {
    perror("sem_post() failed");
    abort();
  }
  return NULL;
}

static void test() {
  int nthreads = 4;
  int i, ret;
  pthread_t* threads = malloc(sizeof(pthread_t) * nthreads);
  sem_t sem;
  ret = sem_init(&sem, 0, 0);
  if (ret == -1) {
    perror("sem_init() failed");
    abort();
  }
  for (i = 0; i < nthreads; ++i) {
    ret = pthread_create(threads + i, NULL, worker, &sem);
    if (ret != 0) {
      errno = ret;
      perror("pthread_create() failed");
      abort();
    }
  }
  for (i = 0; i < nthreads; ++i) {
    do {
      ret = sem_wait(&sem);
    } while (ret == -1 && errno == EINTR);

    if (ret == -1) {
      perror("sem_wait() failed");
      abort();
    }
  }
  ret = sem_destroy(&sem);
  if (ret == -1) {
    perror("sem_destroy() failed");
    abort();
  }
  memset(&sem, 0xac, sizeof(sem));
  for (i = 0; i < nthreads; ++i) {
    ret = pthread_join(threads[i], NULL);
    if (ret != 0) {
      errno = ret;
      perror("pthread_join() failed");
      abort();
    }
  }
  free(threads);
}

int main() {
  int i;
  for (i = 0; i < 100000; ++i)
    test();
  return 0;
}