1sem_getvalue(3C)         Standard C Library Functions         sem_getvalue(3C)
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NAME

6       sem_getvalue - get the value of a semaphore
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SYNOPSIS

9       #include <semaphore.h>
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11       int sem_getvalue(sem_t *restrict sem, int *restrict sval);
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DESCRIPTION

15       The sem_getvalue() function updates the location referenced by the sval
16       argument to have the value of the semaphore referenced by  sem  without
17       affecting  the  state of the semaphore. The updated value represents an
18       actual semaphore value that occurred at some  unspecified  time  during
19       the  call, but it need not be the actual value of the semaphore when it
20       is returned to the calling process.
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23       If sem is locked, then the value returned by sem_getvalue()  is  either
24       zero or a negative number whose absolute value represents the number of
25       processes waiting for the semaphore at some unspecified time during the
26       call.
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29       The  value set in sval may be 0 or positive. If sval is 0, there may be
30       other processes (or LWPs or threads) waiting for the semaphore; if sval
31       is positive, no process is waiting.
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RETURN VALUES

34       Upon  successful  completion,  sem_getvalue()  returns 0. Otherwise, it
35       returns −1 and sets errno to indicate the error.
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ERRORS

38       The  sem_getvalue() function will fail if:
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40       EINVAL     The sem argument does not refer to a valid semaphore.
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43       ENOSYS     The sem_getvalue() function is not supported by the system.
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ATTRIBUTES

47       See attributes(5) for descriptions of the following attributes:
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52       ┌─────────────────────────────┬─────────────────────────────┐
53       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
54       ├─────────────────────────────┼─────────────────────────────┤
55       │Interface Stability          │Committed                    │
56       ├─────────────────────────────┼─────────────────────────────┤
57       │MT-Level                     │MT-Safe                      │
58       ├─────────────────────────────┼─────────────────────────────┤
59       │Standard                     │See standards(5).            │
60       └─────────────────────────────┴─────────────────────────────┘
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SEE ALSO

63       semctl(2),    semget(2),    semop(2),    sem_post(3C),    sem_wait(3C),
64       attributes(5), standards(5)
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68SunOS 5.11                        5 Feb 2008                  sem_getvalue(3C)
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