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.Lb libthr 43.Sh SYNOPSIS 44.In pthread.h 45.Pp 46pthread_once_t 47.Fa once_control 48= PTHREAD_ONCE_INIT; 49.Ft int 50.Fn pthread_once "pthread_once_t *once_control" "void (*init_routine)(void)" 51.Sh DESCRIPTION 52The first call to 53.Fn pthread_once 54by any thread in a process, with a given 55.Fa once_control , 56will call the 57.Fn init_routine 58with no arguments. 59Subsequent calls to 60.Fn pthread_once 61with the same 62.Fa once_control 63will not call the 64.Fn init_routine . 65On return from 66.Fn pthread_once , 67it is guaranteed that 68.Fn init_routine 69has completed. 70The 71.Fa once_control 72parameter is used to determine whether the associated initialization 73routine has been called. 74.Pp 75The function 76.Fn pthread_once 77is not a cancellation point. 78However, if 79.Fn init_routine 80is a cancellation point and is cancelled, the effect on 81.Fa once_control 82is as if 83.Fn pthread_once 84was never called. 85.Pp 86The constant 87.Fa PTHREAD_ONCE_INIT 88is defined by header 89.In pthread.h . 90.Pp 91The behavior of 92.Fn pthread_once 93is undefined if 94.Fa once_control 95has automatic storage duration or is not initialized by 96.Fa PTHREAD_ONCE_INIT . 97.Sh RETURN VALUES 98If successful, the 99.Fn pthread_once 100function will return zero. 101Otherwise an error number will be returned to 102indicate the error. 103.Sh ERRORS 104None. 105.Sh STANDARDS 106The 107.Fn pthread_once 108function conforms to 109.St -p1003.1-96 . 110