1.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by John Birrell. 15.\" 4. Neither the name of the author nor the names of any co-contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" $FreeBSD$ 32.\" 33.Dd April 4, 1996 34.Dt PTHREAD_ONCE 3 35.Os BSD 4 36.Sh NAME 37.Nm pthread_once 38.Nd dynamic package initialization 39.Sh SYNOPSIS 40.Fd #include <pthread.h> 41.Pp 42pthread_once 43.Fa once_control 44= PTHREAD_ONCE_INIT; 45.Ft int 46.Fn pthread_once "pthread_once_t *once_control" "void (*init_routine)(void)" 47.Sh DESCRIPTION 48The first call to 49.Fn pthread_once 50by any thread in a process, with a given 51.Fa once_control , 52will call the 53.Fn init_routine 54with no arguments. Subsequent calls to 55.Fn pthread_once 56with the same 57.Fa once_control 58will not call the 59.Fn init_routine . 60On return from 61.Fn pthread_once , 62it is guaranteed that 63.Fn init_routine 64has completed. The 65.Fa once_control 66parameter is used to determine whether the associated initialization 67routine has been called. 68.Pp 69The function 70.Fn pthread_once 71is not a cancellation point. However, if 72.Fn init_routine 73is a cancellation point and is cancelled, the effect on 74.Fa once_control is as if 75.Fn pthread_once 76was never called. 77.Pp 78The constant 79.Fa PTHREAD_ONCE_INIT 80is defined by header 81.Aq Pa pthread.h . 82.Pp 83The behavior of 84.Fn pthread_once 85is undefined if 86.Fa once_control 87has automatic storage duration or is not initialized by 88.Fa PTHREAD_ONCE_INIT . 89.Pp 90.Sh RETURN VALUES 91If successful, the 92.Fn pthread_once 93function will return zero. Otherwise an error number will be returned to 94indicate the error. 95.Sh ERRORS 96None. 97.Pp 98.Sh STANDARDS 99.Fn pthread_once 100conforms to ISO/IEC 9945-1 ANSI/IEEE 101.Pq Dq Tn POSIX 102Std 1003.1 Second Edition 1996-07-12. 103