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34 .Nd get the value of a semaphore
38 .Fd #include <semaphore.h>
40 .Fn sem_getvalue "sem_t *sem" "int *sval"
44 function sets the variable pointed to by
46 to the current value of the semaphore pointed to by
48 as of the time that the call to
54 returns 0. Otherwise, -1 is returned and
56 is set to indicate the type of
64 points to an invalid semaphore.
72 conforms to ISO/IEC 9945-1 ANSI/IEEE
74 Std 1003.1 1996 Edition.
76 The value of the semaphore is never negative, even if there are threads blocked
77 on the semaphore. POSIX is somewhat ambiguous in its wording with regard to
78 what the value of the semaphore should be if there are blocked waiting threads,
79 but this behavior is conformant, given the wording of the specification.