Move pthread* manpages to lib/libpthread as they are not libc_r specific.
[dragonfly.git] / lib / libpthread / sem_getvalue.3
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28.\" $FreeBSD: src/lib/libc_r/man/sem_getvalue.3,v 1.1.2.7 2001/12/17 10:08:26 ru Exp $
1de703da 29.\" $DragonFly: src/lib/libc_r/man/sem_getvalue.3,v 1.2 2003/06/17 04:26:48 dillon Exp $
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30.Dd February 15, 2000
31.Dt SEM_GETVALUE 3
32.Os
33.Sh NAME
34.Nm sem_getvalue
35.Nd get the value of a semaphore
36.Sh LIBRARY
37.Lb libc_r
38.Sh SYNOPSIS
39.In semaphore.h
40.Ft int
41.Fn sem_getvalue "sem_t *sem" "int *sval"
42.Sh DESCRIPTION
43The
44.Fn sem_getvalue
45function sets the variable pointed to by
46.Fa sval
47to the current value of the semaphore pointed to by
48.Fa sem ,
49as of the time that the call to
50.Fn sem_getvalue
51is actually run.
52.Sh RETURN VALUES
53.Rv -std sem_getvalue
54.Sh ERRORS
55.Fn sem_getvalue
56will fail if:
57.Bl -tag -width Er
58.It Bq Er EINVAL
59.Fa sem
60points to an invalid semaphore.
61.El
62.Sh SEE ALSO
63.Xr sem_post 3 ,
64.Xr sem_trywait 3 ,
65.Xr sem_wait 3
66.Sh STANDARDS
67.Fn sem_getvalue
68conforms to
69.St -p1003.1-96 .
70.Pp
71The value of the semaphore is never negative, even if there are threads blocked
72on the semaphore. POSIX is somewhat ambiguous in its wording with regard to
73what the value of the semaphore should be if there are blocked waiting threads,
74but this behavior is conformant, given the wording of the specification.