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.Dd April 4, 1996 32.Dt PTHREAD_ONCE 3 33.Os 34.Sh NAME 35.Nm pthread_once 36.Nd dynamic package initialization 37.Sh LIBRARY 38.Lb libpthread 39.Sh SYNOPSIS 40.In pthread.h 41.Pp 42pthread_once_t 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. 55Subsequent calls to 56.Fn pthread_once 57with the same 58.Fa once_control 59will not call the 60.Fn init_routine . 61On return from 62.Fn pthread_once , 63it is guaranteed that 64.Fn init_routine 65has completed. 66The 67.Fa once_control 68parameter is used to determine whether the associated initialization 69routine has been called. 70.Pp 71The function 72.Fn pthread_once 73is not a cancellation point. 74However, if 75.Fn init_routine 76is a cancellation point and is cancelled, the effect on 77.Fa once_control 78is as if 79.Fn pthread_once 80was never called. 81.Pp 82The constant 83.Fa PTHREAD_ONCE_INIT 84is defined by header 85.In pthread.h . 86.Pp 87The behavior of 88.Fn pthread_once 89is undefined if 90.Fa once_control 91has automatic storage duration or is not initialized by 92.Fa PTHREAD_ONCE_INIT . 93.Sh RETURN VALUES 94If successful, the 95.Fn pthread_once 96function will return zero. 97Otherwise an error number will be returned to 98indicate the error. 99.Sh ERRORS 100None. 101.Sh STANDARDS 102The 103.Fn pthread_once 104function conforms to 105.St -p1003.1-96 . 106