2001-08-13 16:33:00 +00:00
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.\" Copyright (C) 2000 Jason Evans <jasone@FreeBSD.org>.
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2000-02-16 19:31:53 +00:00
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.\" All rights reserved.
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2001-07-15 07:53:42 +00:00
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.\"
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2000-02-16 19:31:53 +00:00
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice(s), this list of conditions and the following disclaimer as
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.\" the first lines of this file unmodified other than the possible
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.\" addition of one or more copyright notices.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice(s), this list of conditions and the following disclaimer in
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.\" the documentation and/or other materials provided with the
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.\" distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
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.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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2004-07-02 16:45:56 +00:00
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.\"
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2015-01-28 22:42:56 +00:00
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.Dd January 28, 2015
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.Dt SEM_POST 3
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.Os
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.Sh NAME
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.Nm sem_post
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.Nd increment (unlock) a semaphore
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2000-04-22 15:50:29 +00:00
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.Sh LIBRARY
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2004-01-14 20:54:16 +00:00
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.Lb libc
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.Sh SYNOPSIS
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2001-10-01 16:09:29 +00:00
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.In 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
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.Fn sem_post
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function increments (unlocks) the semaphore pointed to by
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.Fa sem .
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If there are threads blocked on the semaphore when
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.Fn sem_post
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is called, then the highest priority thread that has been blocked the longest on
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the semaphore will be allowed to return from
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.Fn sem_wait .
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.Pp
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2003-06-08 10:13:50 +00:00
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The
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.Fn sem_post
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function is signal-reentrant and may be called within signal handlers.
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.Sh RETURN VALUES
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2001-08-09 13:32:13 +00:00
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.Rv -std sem_post
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.Sh ERRORS
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2003-06-08 10:13:50 +00:00
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The
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.Fn sem_post
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The
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.Fa sem
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argument
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points to an invalid semaphore.
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.It Bq Er EOVERFLOW
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The semaphore value would exceed
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.Dv SEM_VALUE_MAX .
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.El
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.Sh SEE ALSO
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2005-07-13 13:15:22 +00:00
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.Xr sem_getvalue 3 ,
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.Xr sem_trywait 3 ,
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.Xr sem_wait 3
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.Sh STANDARDS
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The
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.Fn sem_post
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function conforms to
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2001-02-26 15:16:43 +00:00
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.St -p1003.1-96 .
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