66 lines
1.8 KiB
Groff
66 lines
1.8 KiB
Groff
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.\" $Darwin$
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.\"
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.\" Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
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.\"
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.\" @APPLE_LICENSE_HEADER_START@
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.\"
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.\" The contents of this file constitute Original Code as defined in and
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.\" are subject to the Apple Public Source License Version 1.1 (the
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.\" "License"). You may not use this file except in compliance with the
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.\" License. Please obtain a copy of the License at
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.\" http://www.apple.com/publicsource and read it before using this file.
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.\"
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.\" This Original Code and all software distributed under the License are
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.\" distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
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.\" EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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.\" INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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.\" FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
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.\" License for the specific language governing rights and limitations
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.\" under the License.
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.\"
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.\" @APPLE_LICENSE_HEADER_END@
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.\"
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.Dd June 8, 2000
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.Dt SEM_POST 2
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.Os Darwin
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.Sh NAME
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.Nm sem_post
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.Nd unlock a semaphore
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.Sh SYNOPSIS
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.Fd #include <semaphore.h>
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.Ft int
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.Fn sem_post "sem_t *sem"
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.Sh DESCRIPTION
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The semaphore referenced by
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.Fa sem
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is unlocked, the value of the semaphore is incremented, and all
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threads which are waiting on the semaphore are awakened.
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.Pp
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.Fn sem_post
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is reentrant with respect to signals and may be called from within a
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signal hanlder.
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.Pp
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If successful,
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.Fn sem_post
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will return 0. Otherwise, -1 is returned and
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.Va errno
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is set.
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.Sh ERRORS
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.Fn sem_post
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succeeds unless:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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.Fa sem
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is not a valid semaphore descriptor.
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.El
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.Sh SEE ALSO
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.Xr sem_open 2 ,
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.Xr sem_trywait 2 ,
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.Xr sem_wait 2 ,
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.Xr semctl 2 ,
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.Xr semget 2 ,
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.Xr semop 2
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.Sh HISTORY
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.Fn sem_post
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is specified in the POSIX Realtime Extension (1003.1b-1993/1003.1i-1995).
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