| SEM_GETVALUE(3) | Library Functions Manual | SEM_GETVALUE(3) | 
sem_getvalue —
#include <semaphore.h>
int
  
  sem_getvalue(sem_t
    * restrict sem, int *
    restrict sval);
sem_getvalue() function sets the variable pointed to
  by sval to the current value of the semaphore pointed to
  by sem, as of the time that the call to
  sem_getvalue() is actually run.
sem_getvalue() function returns the value 0
  if successful; otherwise the value -1 is returned and the global
  variable errno is set to indicate the error.
sem_getvalue() will fail if:
EINVAL]sem_getvalue() conforms to ISO/IEC
  9945-1:1996 (“POSIX.1”).
The value of the semaphore is never negative, even if there are threads blocked on the semaphore. POSIX is somewhat ambiguous in its wording with regard to what the value of the semaphore should be if there are blocked waiting threads, but this behavior is conformant, given the wording of the specification.
| February 29, 2012 | NetBSD 9.4 |