1.\" $NetBSD: pthread_once.3,v 1.7 2010/07/09 08:51:28 jruoho Exp $ 2.\" 3.\" Copyright (c) 2002 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 15.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 16.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 17.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 18.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 19.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 20.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 21.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 22.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 23.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 24.\" POSSIBILITY OF SUCH DAMAGE. 25.\" 26.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>. 27.\" All rights reserved. 28.\" 29.\" Redistribution and use in source and binary forms, with or without 30.\" modification, are permitted provided that the following conditions 31.\" are met: 32.\" 1. Redistributions of source code must retain the above copyright 33.\" notice, this list of conditions and the following disclaimer. 34.\" 2. Redistributions in binary form must reproduce the above copyright 35.\" notice, this list of conditions and the following disclaimer in the 36.\" documentation and/or other materials provided with the distribution. 37.\" 3. All advertising materials mentioning features or use of this software 38.\" must display the following acknowledgement: 39.\" This product includes software developed by John Birrell. 40.\" 4. Neither the name of the author nor the names of any co-contributors 41.\" may be used to endorse or promote products derived from this software 42.\" without specific prior written permission. 43.\" 44.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND 45.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 46.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 47.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 48.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 49.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 50.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 51.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 52.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 53.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 54.\" SUCH DAMAGE. 55.\" 56.\" $FreeBSD: src/lib/libpthread/man/pthread_once.3,v 1.14 2002/09/16 19:29:29 mini Exp $ 57.\" 58.Dd July 9, 2010 59.Dt PTHREAD_ONCE 3 60.Os 61.Sh NAME 62.Nm pthread_once 63.Nd dynamic package initialization 64.Sh LIBRARY 65.Lb libpthread 66.Sh SYNOPSIS 67.In pthread.h 68.Ft int 69.Fn pthread_once "pthread_once_t *once_control" "void (*init_routine)(void)" 70.Pp 71.Va pthread_once_t once_control = Dv PTHREAD_ONCE_INIT; 72.Sh DESCRIPTION 73The first call to 74.Fn pthread_once 75by any thread in a process, with a given 76.Fa once_control , 77will call the 78.Fn init_routine 79with no arguments. 80Subsequent calls to 81.Fn pthread_once 82with the same 83.Fa once_control 84will not call the 85.Fn init_routine . 86On return from 87.Fn pthread_once , 88it is guaranteed that 89.Fn init_routine 90has completed. 91The 92.Fa once_control 93parameter is used to determine whether the associated initialization 94routine has been called. 95.Pp 96The function 97.Fn pthread_once 98is not a cancellation point. 99However, if 100.Fn init_routine 101is a cancellation point and is cancelled, the effect on 102.Fa once_control 103is as if 104.Fn pthread_once 105was never called. 106.Pp 107The constant 108.Dv PTHREAD_ONCE_INIT 109initializes the static once synchronization control structure 110.Fa once_control 111to be used with 112.Fn pthread_once . 113The behavior of 114.Fn pthread_once 115is undefined if 116.Fa once_control 117has automatic storage duration or is not initialized by 118.Dv PTHREAD_ONCE_INIT . 119.Sh RETURN VALUES 120If successful, the 121.Fn pthread_once 122function will return zero. 123Otherwise an error number will be returned to 124indicate the error. 125.Sh ERRORS 126None. 127.Sh STANDARDS 128The function conforms to 129.St -p1003.1-2001 . 130