109 lines
3.2 KiB
Groff
109 lines
3.2 KiB
Groff
.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>.
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.\" All rights reserved.
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.\"
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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, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by John Birrell.
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.\" 4. Neither the name of the author nor the names of any co-contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd April 4, 1996
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.Dt PTHREAD_ONCE 3
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.Os BSD 4
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.Sh NAME
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.Nm pthread_once
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.Nd dynamic package initialization
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.Sh LIBRARY
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.Lb libc_r
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.Sh SYNOPSIS
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.Fd #include <pthread.h>
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.Pp
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pthread_once_t
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.Fa once_control
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= PTHREAD_ONCE_INIT;
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.Ft int
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.Fn pthread_once "pthread_once_t *once_control" "void (*init_routine)(void)"
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.Sh DESCRIPTION
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The first call to
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.Fn pthread_once
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by any thread in a process, with a given
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.Fa once_control ,
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will call the
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.Fn init_routine
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with no arguments.
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Subsequent calls to
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.Fn pthread_once
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with the same
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.Fa once_control
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will not call the
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.Fn init_routine .
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On return from
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.Fn pthread_once ,
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it is guaranteed that
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.Fn init_routine
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has completed.
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The
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.Fa once_control
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parameter is used to determine whether the associated initialization
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routine has been called.
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.Pp
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The function
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.Fn pthread_once
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is not a cancellation point.
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However, if
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.Fn init_routine
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is a cancellation point and is cancelled, the effect on
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.Fa once_control is as if
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.Fn pthread_once
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was never called.
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.Pp
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The constant
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.Fa PTHREAD_ONCE_INIT
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is defined by header
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.Aq Pa pthread.h .
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.Pp
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The behavior of
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.Fn pthread_once
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is undefined if
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.Fa once_control
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has automatic storage duration or is not initialized by
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.Fa PTHREAD_ONCE_INIT .
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.Pp
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.Sh RETURN VALUES
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If successful, the
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.Fn pthread_once
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function will return zero.
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Otherwise an error number will be returned to
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indicate the error.
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.Sh ERRORS
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None.
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.Pp
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.Sh STANDARDS
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.Fn pthread_once
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conforms to ISO/IEC 9945-1 ANSI/IEEE
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.Pq Dq Tn POSIX
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Std 1003.1 Second Edition 1996-07-12.
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