|File: [cvs.NetBSD.org] / src / lib / libc / gen / pthread_atfork.3 (download)
Revision 126.96.36.199, Sat Jun 18 11:02:47 2005 UTC (14 years, 5 months ago) by tron
CVS Tags: netbsd-3-1-RELEASE, netbsd-3-1-RC4, netbsd-3-1-RC3, netbsd-3-1-RC2, netbsd-3-1-RC1, netbsd-3-1-1-RELEASE, netbsd-3-1, netbsd-3-0-RELEASE, netbsd-3-0-RC6, netbsd-3-0-RC5, netbsd-3-0-RC4, netbsd-3-0-RC3, netbsd-3-0-RC2, netbsd-3-0-RC1, netbsd-3-0-3-RELEASE, netbsd-3-0-2-RELEASE, netbsd-3-0-1-RELEASE, netbsd-3-0
Changes since 1.3: +3 -3
Pull up revision 1.4 (requested by peter in ticket #473):
Fix some spelling errors.
From Igor Sobrado in PR/29997.
.\" $NetBSD: pthread_atfork.3,v 188.8.131.52 2005/06/18 11:02:47 tron Exp $
.\" Copyright (c) 2003 The NetBSD Foundation, Inc.
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Nathan J. Williams.
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.Dd February 12, 2003
.Dt PTHREAD_ATFORK 3
.Nd register handlers to be called when process forks
.Fn pthread_atfork "void (*prepare)(void)" "void (*parent)(void)" "void (*child)(void)"
function registers the provided handler functions to be called when the
.Xr fork 2
function is called.
Each of the three handlers is called at a different place in the
.Xr fork 2
handler is called in the parent process before the fork happens, the
handler is called in the parent process after the fork has happened, and the
handler is called in the child process after the fork has happened.
handlers are called in the order in which they were registered, while the
handlers are called in reverse of the order in which they were registered.
Any of the handlers given may be
.Dv NULL .
The intended use of
is to provide a consistent state to a child process from a multithreaded parent
process where locks may be acquired and released asynchronously with respect to the
.Xr fork 2
Each subsystem with locks that are used in a child process should register
that acquires those locks in the
handler and releases them in the
.Sh RETURN VALUES
function returns 0 on success and an error number on failure.
The following error code may be returned:
.Bl -tag -width Er
.It Bq Er ENOMEM
Insufficient memory exists to register the fork handlers.
.Sh SEE ALSO
.Xr fork 2
function conforms to
.St -p1003.1c-95 .
function first appeared in
.Nx 2.0 .
.Xr fork 2
from a multithreaded process, it is only safe to call
async-signal-safe functions until calling one of the
.Xr exec 3
functions are not async-signal-safe, so it is not safe to use such functions
There is no way to unregister a handler registered with
.Fn pthread_atfork .