destroy an unnamed semaphore
function destroys the unnamed semaphore pointed to by
sem. After a successful call to
sem_destroy(), sem is unusable
until re-initialized by another call to
sem_destroy() function returns the
value 0 if successful; otherwise the value -1 is returned and
the global variable errno is set to indicate the
sem_destroy() will fail if:
- sem points to an invalid semaphore.
- There are currently threads blocked on the semaphore that sem points to.
sem_getvalue(3), sem_init(3), sem_open(3), sem_post(3), sem_wait(3)
sem_destroy() conforms to
ISO/IEC 9945-1:1996 (“POSIX.1”).
POSIX does not define the behavior of
sem_destroy() if called while there are threads
blocked on sem, but this implementation is guaranteed
to return -1 and set errno to
EBUSY if there are threads blocked on