18e234adfSJason Evans.\" Copyright (C) 2000 Jason Evans <jasone@freebsd.org>. 2b0a1b4f8SJason Evans.\" All rights reserved. 3b0a1b4f8SJason Evans.\" 4b0a1b4f8SJason Evans.\" Redistribution and use in source and binary forms, with or without 5b0a1b4f8SJason Evans.\" modification, are permitted provided that the following conditions 6b0a1b4f8SJason Evans.\" are met: 7b0a1b4f8SJason Evans.\" 1. Redistributions of source code must retain the above copyright 8b0a1b4f8SJason Evans.\" notice(s), this list of conditions and the following disclaimer as 9b0a1b4f8SJason Evans.\" the first lines of this file unmodified other than the possible 10b0a1b4f8SJason Evans.\" addition of one or more copyright notices. 11b0a1b4f8SJason Evans.\" 2. Redistributions in binary form must reproduce the above copyright 12b0a1b4f8SJason Evans.\" notice(s), this list of conditions and the following disclaimer in 13b0a1b4f8SJason Evans.\" the documentation and/or other materials provided with the 14b0a1b4f8SJason Evans.\" distribution. 15b0a1b4f8SJason Evans.\" 16b0a1b4f8SJason Evans.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 17b0a1b4f8SJason Evans.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18b0a1b4f8SJason Evans.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19b0a1b4f8SJason Evans.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE 20b0a1b4f8SJason Evans.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21b0a1b4f8SJason Evans.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22b0a1b4f8SJason Evans.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 23b0a1b4f8SJason Evans.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 24b0a1b4f8SJason Evans.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 25b0a1b4f8SJason Evans.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 26b0a1b4f8SJason Evans.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27b0a1b4f8SJason Evans.\" 28b0a1b4f8SJason Evans.\" $FreeBSD$ 29b0a1b4f8SJason Evans.Dd February 15, 2000 30b0a1b4f8SJason Evans.Dt SEM_POST 3 31b0a1b4f8SJason Evans.Os 32b0a1b4f8SJason Evans.Sh NAME 33b0a1b4f8SJason Evans.Nm sem_post 34b0a1b4f8SJason Evans.Nd increment (unlock) a semaphore 35d8a78688SAlexey Zelkin.Sh LIBRARY 36d8a78688SAlexey Zelkin.Lb libc_r 37b0a1b4f8SJason Evans.Sh SYNOPSIS 38b0a1b4f8SJason Evans.Fd #include <semaphore.h> 39b0a1b4f8SJason Evans.Ft int 40b0a1b4f8SJason Evans.Fn sem_post "sem_t *sem" 41b0a1b4f8SJason Evans.Sh DESCRIPTION 42b0a1b4f8SJason EvansThe 43b0a1b4f8SJason Evans.Fn sem_post 44b0a1b4f8SJason Evansfunction increments (unlocks) the semaphore pointed to by 45b0a1b4f8SJason Evans.Fa sem . 46b0a1b4f8SJason EvansIf there are threads blocked on the semaphore when 47b0a1b4f8SJason Evans.Fn sem_post 48b0a1b4f8SJason Evansis called, then the highest priority thread that has been blocked the longest on 49b0a1b4f8SJason Evansthe semaphore will be allowed to return from 50b0a1b4f8SJason Evans.Fn sem_wait . 51b167c9a5SJason Evans.Pp 52b167c9a5SJason Evans.Fn sem_post 53b167c9a5SJason Evansis signal-reentrant and may be called within signal handlers. 54b0a1b4f8SJason Evans.Sh RETURN VALUES 55b0a1b4f8SJason EvansIf successful, 56b0a1b4f8SJason Evans.Fn sem_post 57b0a1b4f8SJason Evansreturns 0. Otherwise, -1 is returned and 58b0a1b4f8SJason Evans.Va errno 59b0a1b4f8SJason Evansis set to indicate the type of 60b0a1b4f8SJason Evanserror. 61b0a1b4f8SJason Evans.Sh ERRORS 62b0a1b4f8SJason Evans.Fn sem_post 63b0a1b4f8SJason Evanswill fail if: 64b0a1b4f8SJason Evans.Bl -tag -width Er 65b0a1b4f8SJason Evans.It Bq Er EINVAL 66b0a1b4f8SJason Evans.Fa sem 67b0a1b4f8SJason Evanspoints to an invalid semaphore. 68b0a1b4f8SJason Evans.El 69b0a1b4f8SJason Evans.Sh SEE ALSO 7082db3da3SJason Evans.Xr sem_trywait 3 , 7182db3da3SJason Evans.Xr sem_wait 3 72b0a1b4f8SJason Evans.Sh STANDARDS 73b0a1b4f8SJason Evans.Fn sem_post 74b0a1b4f8SJason Evansconforms to ISO/IEC 9945-1 ANSI/IEEE 75b0a1b4f8SJason Evans.Pq Dq Tn POSIX 76b0a1b4f8SJason EvansStd 1003.1 1996 Edition. 77