xref: /freebsd-src/share/man/man3/pthread_atfork.3 (revision fa9896e082a1046ff4fbc75fcba4d18d1f2efc19)

.\" Copyright (c) 2004 Alex Vasylenko <lxv@omut.org>
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.\" Portions of this text are reprinted and reproduced in electronic form
.\" from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology --
.\" Portable Operating System Interface (POSIX), The Open Group Base
.\" Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of
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.\" event of any discrepancy between this version and the original IEEE and
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.Dd June 21, 2004
.Dt PTHREAD_ATFORK 3
.Os
.Sh NAME
.Nm pthread_atfork
.Nd register fork handlers
.Sh LIBRARY
.Lb libpthread
.Sh SYNOPSIS
.In pthread.h
.Ft int
.Fo pthread_atfork
.Fa "void \*[lp]*prepare\*[rp]\*[lp]void\*[rp]"
.Fa "void \*[lp]*parent\*[rp]\*[lp]void\*[rp]"
.Fa "void \*[lp]*child\*[rp]\*[lp]void\*[rp]"
.Fc
.Sh DESCRIPTION
The
.Fn pthread_atfork
function declares fork handlers to be called before and after
.Xr fork 2 ,
in the context of the thread that called
.Xr fork 2 .
.Pp
The handlers registered with
.Fn pthread_atfork
are called at the moments in time described below:
.Bl -tag -width ".Fa prepare"
.It Fa prepare
Before
.Xr fork 2
processing commences in the parent process.
If more than one
.Fa prepare
handler is registered they will be called in the opposite order
they were registered.
.It Fa parent
After
.Xr fork 2
completes in the parent process.
If more than one
.Fa parent
handler is registered they will be called in the same order
they were registered.
.It Fa child
After
.Xr fork 2
processing completes in the child process.
If more than one
.Fa child
handler is registered they will be called in the same order
they were registered.
.El
.Pp
If no handling is desired at one or more of these three points,
a null pointer may be passed as the corresponding fork handler.
.Sh RETURN VALUES
If successful, the
.Fn pthread_atfork
function will return zero.
Otherwise an error number will be returned to indicate the error.
.Sh ERRORS
The
.Fn pthread_atfork
function will fail if:
.Bl -tag -width Er
.It Bq Er ENOMEM
Insufficient table space exists to record the fork handler addresses.
.El
.Sh SEE ALSO
.Xr fork 2 ,
.Xr pthread 3
.Sh STANDARDS
The
.Fn pthread_atfork
function is expected to conform to
.St -p1003.1 .
.Sh AUTHORS
This manpage was written by
.An Alex Vasylenko Aq Mt lxv@omut.org .