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 36.Sh NAME 37.Nm pthread_once 38.Nd dynamic package initialization 39.Sh LIBRARY 40.Lb libc_r 41.Lb libpthread 42.Sh SYNOPSIS 43.In pthread.h 44.Pp 45pthread_once_t 46.Fa once_control 47= PTHREAD_ONCE_INIT; 48.Ft int 49.Fn pthread_once "pthread_once_t *once_control" "void (*init_routine)(void)" 50.Sh DESCRIPTION 51The first call to 52.Fn pthread_once 53by any thread in a process, with a given 54.Fa once_control , 55will call the 56.Fn init_routine 57with no arguments. 58Subsequent calls to 59.Fn pthread_once 60with the same 61.Fa once_control 62will not call the 63.Fn init_routine . 64On return from 65.Fn pthread_once , 66it is guaranteed that 67.Fn init_routine 68has completed. 69The 70.Fa once_control 71parameter is used to determine whether the associated initialization 72routine has been called. 73.Pp 74The function 75.Fn pthread_once 76is not a cancellation point. 77However, if 78.Fn init_routine 79is a cancellation point and is cancelled, the effect on 80.Fa once_control is as if 81.Fn pthread_once 82was never called. 83.Pp 84The constant 85.Fa PTHREAD_ONCE_INIT 86is defined by header 87.In pthread.h . 88.Pp 89The behavior of 90.Fn pthread_once 91is undefined if 92.Fa once_control 93has automatic storage duration or is not initialized by 94.Fa PTHREAD_ONCE_INIT . 95.Sh RETURN VALUES 96If successful, the 97.Fn pthread_once 98function will return zero. 99Otherwise an error number will be returned to 100indicate the error. 101.Sh ERRORS 102None. 103.Sh STANDARDS 104The 105.Fn pthread_once 106function conforms to 107.St -p1003.1-96 . 108