1.\" $NetBSD: pthread_once.3,v 1.2 2003/06/08 06:44:32 thorpej 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.\" 3. Neither the name of The NetBSD Foundation nor the names of its 14.\" contributors may be used to endorse or promote products derived 15.\" from this software without specific prior written permission. 16.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26.\" POSSIBILITY OF SUCH DAMAGE. 27.\" 28.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>. 29.\" All rights reserved. 30.\" 31.\" Redistribution and use in source and binary forms, with or without 32.\" modification, are permitted provided that the following conditions 33.\" are met: 34.\" 1. Redistributions of source code must retain the above copyright 35.\" notice, this list of conditions and the following disclaimer. 36.\" 2. Redistributions in binary form must reproduce the above copyright 37.\" notice, this list of conditions and the following disclaimer in the 38.\" documentation and/or other materials provided with the distribution. 39.\" 3. All advertising materials mentioning features or use of this software 40.\" must display the following acknowledgement: 41.\" This product includes software developed by John Birrell. 42.\" 4. Neither the name of the author nor the names of any co-contributors 43.\" may be used to endorse or promote products derived from this software 44.\" without specific prior written permission. 45.\" 46.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND 47.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 48.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 49.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 50.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 51.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 52.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 53.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 54.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 55.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 56.\" SUCH DAMAGE. 57.\" 58.\" $FreeBSD: src/lib/libpthread/man/pthread_once.3,v 1.14 2002/09/16 19:29:29 mini Exp $ 59.\" 60.Dd January 30, 2003 61.Dt PTHREAD_ONCE 3 62.Os 63.Sh NAME 64.Nm pthread_once 65.Nd dynamic package initialization 66.Sh LIBRARY 67.Lb libpthread 68.Sh SYNOPSIS 69.In pthread.h 70.Pp 71pthread_once_t 72.Fa once_control 73= PTHREAD_ONCE_INIT; 74.Ft int 75.Fn pthread_once "pthread_once_t *once_control" "void (*init_routine)(void)" 76.Sh DESCRIPTION 77The first call to 78.Fn pthread_once 79by any thread in a process, with a given 80.Fa once_control , 81will call the 82.Fn init_routine 83with no arguments. 84Subsequent calls to 85.Fn pthread_once 86with the same 87.Fa once_control 88will not call the 89.Fn init_routine . 90On return from 91.Fn pthread_once , 92it is guaranteed that 93.Fn init_routine 94has completed. 95The 96.Fa once_control 97parameter is used to determine whether the associated initialization 98routine has been called. 99.Pp 100The function 101.Fn pthread_once 102is not a cancellation point. 103However, if 104.Fn init_routine 105is a cancellation point and is cancelled, the effect on 106.Fa once_control 107is as if 108.Fn pthread_once 109was never called. 110.Pp 111The constant 112.Fa PTHREAD_ONCE_INIT 113is defined by header 114.Aq Pa pthread.h . 115.Pp 116The behavior of 117.Fn pthread_once 118is undefined if 119.Fa once_control 120has automatic storage duration or is not initialized by 121.Fa PTHREAD_ONCE_INIT . 122.Sh RETURN VALUES 123If successful, the 124.Fn pthread_once 125function will return zero. 126Otherwise an error number will be returned to 127indicate the error. 128.Sh ERRORS 129None. 130.Sh STANDARDS 131.Fn pthread_once 132conforms to 133.St -p1003.1-96 . 134