1.\" Copyright (C) 2000 Jason Evans <jasone@FreeBSD.org>. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as --- 11 unchanged lines hidden (view full) --- 20.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 23.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 24.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 25.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 26.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27.\" |
28.\" $FreeBSD: head/lib/libc/gen/sem_getvalue.3 112542 2003-03-24 16:05:24Z charnier $ |
29.Dd February 15, 2000 30.Dt SEM_GETVALUE 3 31.Os 32.Sh NAME 33.Nm sem_getvalue 34.Nd get the value of a semaphore 35.Sh LIBRARY 36.Lb libc_r --- 9 unchanged lines hidden (view full) --- 46to the current value of the semaphore pointed to by 47.Fa sem , 48as of the time that the call to 49.Fn sem_getvalue 50is actually run. 51.Sh RETURN VALUES 52.Rv -std sem_getvalue 53.Sh ERRORS |
54The |
55.Fn sem_getvalue |
56function will 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.Xr sem 4 67.Sh STANDARDS |
68The |
69.Fn sem_getvalue |
70function conforms to |
71.St -p1003.1-96 . 72.Pp 73The value of the semaphore is never negative, even if there are threads blocked 74on the semaphore. POSIX is somewhat ambiguous in its wording with regard to 75what the value of the semaphore should be if there are blocked waiting threads, 76but this behavior is conformant, given the wording of the specification. |