.\" Copyright (c) 1996 John Birrell <email@example.com>. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by John Birrell. .\" 4. Neither the name of the author nor the names of any co-contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $FreeBSD: src/lib/libc_r/man/pthread_once.3,v 184.108.40.206 2001/08/17 15:42:52 ru Exp $ .\" .Dd April 4, 1996 .Dt PTHREAD_ONCE 3 .Os .Sh NAME .Nm pthread_once .Nd dynamic package initialization .Sh SYNOPSIS .Fd #include <pthread.h> .Pp pthread_once_t .Fa once_control = PTHREAD_ONCE_INIT; .Ft int .Fn pthread_once "pthread_once_t *once_control" "void (*init_routine)(void)" .Sh DESCRIPTION The first call to .Fn pthread_once by any thread in a process, with a given .Fa once_control , will call the .Fn init_routine with no arguments. Subsequent calls to .Fn pthread_once with the same .Fa once_control will not call the .Fn init_routine . On return from .Fn pthread_once , it is guaranteed that .Fn init_routine has completed. The .Fa once_control parameter is used to determine whether the associated initialization routine has been called. .Pp The function .Fn pthread_once is not a cancellation point. However, if .Fn init_routine is a cancellation point and is cancelled, the effect on .Fa once_control is as if .Fn pthread_once was never called. .Pp The constant .Fa PTHREAD_ONCE_INIT is defined by header .Aq Pa pthread.h . .Pp The behavior of .Fn pthread_once is undefined if .Fa once_control has automatic storage duration or is not initialized by .Fa PTHREAD_ONCE_INIT . .Sh RETURN VALUES If successful, the .Fn pthread_once function will return zero. Otherwise an error number will be returned to indicate the error. .Sh ERRORS None. .Sh STANDARDS .Fn pthread_once conforms to .St -p1003.1-96 .