The implementation of sem_timedwait which is in semaphore.c, is not POSIX 
compliant in regards to returning errors.  It is supposed to return 0 or -1, and 
put the error in errno, which it doesn't do, but instead returns the error 
directly.  Below is the patch to the latest in CVS.

--- semaphore.c.orig    2004-04-26 14:29:11.000000000 -0400
+++ semaphore.c 2004-04-26 14:30:19.000000000 -0400
@@ -225,7 +225,8 @@
     /* The standard requires that if the function would block and the
        time value is illegal, the function returns with an error.  */
     __pthread_unlock(&sem->__sem_lock);
-    return EINVAL;
+    errno = EINVAL;
+    return -1;
   }

   /* Set up extrication interface */
@@ -263,7 +264,8 @@

        if (was_on_queue) {
          __pthread_set_own_extricate_if(self, 0);
-         return ETIMEDOUT;
+        errno = ETIMEDOUT;
+        return -1;
        }

        /* Eat the outstanding restart() from the signaller */