+typedef struct xbt_os_sem_ {
+#ifndef HAVE_SEM_INIT
+ char *name;
+#endif
+ sem_t s;
+ sem_t *ps;
+} s_xbt_os_sem_t;
+
+#ifndef SEM_FAILED
+#define SEM_FAILED (-1)
+#endif
+
+xbt_os_sem_t xbt_os_sem_init(unsigned int value)
+{
+ xbt_os_sem_t res = xbt_new(s_xbt_os_sem_t, 1);
+
+ /* On some systems (MAC OS X), only the stub of sem_init is to be found.
+ * Any attempt to use it leads to ENOSYS (function not implemented).
+ * If such a prehistoric system is detected, do the job with sem_open instead
+ */
+#ifdef HAVE_SEM_INIT
+ if (sem_init(&(res->s), 0, value) != 0)
+ THROWF(system_error, errno, "sem_init() failed: %s", strerror(errno));
+ res->ps = &(res->s);
+
+#else /* damn, no sem_init(). Reimplement it */
+
+ xbt_os_mutex_acquire(next_sem_ID_lock);
+ res->name = bprintf("/%d", ++next_sem_ID);
+ xbt_os_mutex_release(next_sem_ID_lock);
+
+ res->ps = sem_open(res->name, O_CREAT, 0644, value);
+ if ((res->ps == (sem_t *) SEM_FAILED) && (errno == ENAMETOOLONG)) {
+ /* Old darwins only allow 13 chars. Did you create *that* amount of semaphores? */
+ res->name[13] = '\0';
+ res->ps = sem_open(res->name, O_CREAT, 0644, value);
+ }
+ if ((res->ps == (sem_t *) SEM_FAILED))
+ THROWF(system_error, errno, "sem_open() failed: %s", strerror(errno));
+
+ /* Remove the name from the semaphore namespace: we never join on it */
+ if (sem_unlink(res->name) < 0)
+ THROWF(system_error, errno, "sem_unlink() failed: %s",
+ strerror(errno));
+
+#endif
+
+ return res;
+}
+
+void xbt_os_sem_acquire(xbt_os_sem_t sem)
+{
+ if (!sem)
+ THROWF(arg_error, EINVAL, "Cannot acquire of the NULL semaphore");
+ if (sem_wait(sem->ps) < 0)
+ THROWF(system_error, errno, "sem_wait() failed: %s", strerror(errno));
+}
+
+void xbt_os_sem_timedacquire(xbt_os_sem_t sem, double delay)
+{
+ int errcode;
+
+ if (!sem)
+ THROWF(arg_error, EINVAL, "Cannot acquire of the NULL semaphore");
+
+ if (delay < 0) {
+ xbt_os_sem_acquire(sem);
+ } else if (delay == 0) {
+ errcode = sem_trywait(sem->ps);
+
+ switch (errcode) {
+ case 0:
+ return;
+ case ETIMEDOUT:
+ THROWF(timeout_error, 0, "semaphore %p not ready", sem);
+ default:
+ THROWF(system_error, errcode,
+ "xbt_os_sem_timedacquire(%p) failed: %s", sem,
+ strerror(errcode));
+ }
+
+ } else {
+#ifdef HAVE_SEM_WAIT
+ struct timespec ts_end;
+ double end = delay + xbt_os_time();
+
+ ts_end.tv_sec = (time_t) floor(end);
+ ts_end.tv_nsec = (long) ((end - ts_end.tv_sec) * 1000000000);
+ XBT_DEBUG("sem_timedwait(%p,%p)", sem->ps, &ts_end);
+ errcode = sem_timedwait(sem->s, &ts_end);
+
+#else /* Okay, reimplement this function then */
+ double start = xbt_os_time();
+ do {
+ errcode = sem_trywait(sem->ps);
+ if (errcode == EBUSY)
+ xbt_os_thread_yield();
+ } while (errcode == EBUSY && xbt_os_time() - start < delay);
+
+ if (errcode == EBUSY)
+ errcode = ETIMEDOUT;
+#endif
+
+ switch (errcode) {
+ case 0:
+ return;
+
+ case ETIMEDOUT:
+ THROWF(timeout_error, delay,
+ "semaphore %p wasn't signaled before timeout (%f)", sem,
+ delay);
+
+ default:
+ THROWF(system_error, errcode, "sem_timedwait(%p,%f) failed: %s", sem,
+ delay, strerror(errcode));
+ }
+ }
+}
+
+void xbt_os_sem_release(xbt_os_sem_t sem)
+{
+ if (!sem)
+ THROWF(arg_error, EINVAL, "Cannot release of the NULL semaphore");
+
+ if (sem_post(sem->ps) < 0)
+ THROWF(system_error, errno, "sem_post() failed: %s", strerror(errno));
+}
+
+void xbt_os_sem_destroy(xbt_os_sem_t sem)
+{
+ if (!sem)
+ THROWF(arg_error, EINVAL, "Cannot destroy the NULL sempahore");
+
+#ifdef HAVE_SEM_INIT
+ if (sem_destroy(sem->ps) < 0)
+ THROWF(system_error, errno, "sem_destroy() failed: %s",
+ strerror(errno));
+#else
+ if (sem_close(sem->ps) < 0)
+ THROWF(system_error, errno, "sem_close() failed: %s", strerror(errno));
+ xbt_free(sem->name);
+
+#endif
+ xbt_free(sem);
+}
+
+void xbt_os_sem_get_value(xbt_os_sem_t sem, int *svalue)
+{
+ if (!sem)
+ THROWF(arg_error, EINVAL,
+ "Cannot get the value of the NULL semaphore");
+
+ if (sem_getvalue(&(sem->s), svalue) < 0)
+ THROWF(system_error, errno, "sem_getvalue() failed: %s",
+ strerror(errno));