1.\" $NetBSD: pthread_once.3,v 1.3 2008/05/02 18:11:04 martin 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 January 30, 2003 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.Pp 69pthread_once_t 70.Fa once_control 71= PTHREAD_ONCE_INIT; 72.Ft int 73.Fn pthread_once "pthread_once_t *once_control" "void (*init_routine)(void)" 74.Sh DESCRIPTION 75The first call to 76.Fn pthread_once 77by any thread in a process, with a given 78.Fa once_control , 79will call the 80.Fn init_routine 81with no arguments. 82Subsequent calls to 83.Fn pthread_once 84with the same 85.Fa once_control 86will not call the 87.Fn init_routine . 88On return from 89.Fn pthread_once , 90it is guaranteed that 91.Fn init_routine 92has completed. 93The 94.Fa once_control 95parameter is used to determine whether the associated initialization 96routine has been called. 97.Pp 98The function 99.Fn pthread_once 100is not a cancellation point. 101However, if 102.Fn init_routine 103is a cancellation point and is cancelled, the effect on 104.Fa once_control 105is as if 106.Fn pthread_once 107was never called. 108.Pp 109The constant 110.Fa PTHREAD_ONCE_INIT 111is defined by header 112.Aq Pa pthread.h . 113.Pp 114The behavior of 115.Fn pthread_once 116is undefined if 117.Fa once_control 118has automatic storage duration or is not initialized by 119.Fa PTHREAD_ONCE_INIT . 120.Sh RETURN VALUES 121If successful, the 122.Fn pthread_once 123function will return zero. 124Otherwise an error number will be returned to 125indicate the error. 126.Sh ERRORS 127None. 128.Sh STANDARDS 129.Fn pthread_once 130conforms to 131.St -p1003.1-96 . 132