.\" Copyright (c) 2007 The DragonFly Project.  All rights reserved.
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.\" This code is derived from software contributed to The DragonFly Project
.\" by Simon 'corecode' Schubert <corecode@fs.ei.tum.de>
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.\" $DragonFly: src/lib/libc/sys/extexit.2,v 1.5 2008/05/02 02:05:04 swildner Exp $
.\"
.Dd February 24, 2007
.Dt EXTEXIT 2
.Os
.Sh NAME
.Nm extexit
.Nd terminate the calling lwp or process and perform action
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft void
.Fn extexit "int how" "int status" "void *addr"
.Sh DESCRIPTION
The
.Fn extexit
function terminates a lwp or process and performs an action.
This is a low level service routine not intended to be used
from common user code.
.Pp
The
.Fn extexit
function can be used to either exit a lwp or a complete process.
This is done by specifying either
.Dv EXTEXIT_PROC
or
.Dv EXTEXIT_LWP
in
.Fa how .
If exiting the process or if exiting the last lwp of a process,
.Fn extexit
behaves like
.Xr _exit 2
called with the
.Fa status
argument.
.Pp
Additionally,
.Fn extexit
can be used to perform certain actions when exiting.
The following actions can be specified by
.Em or Ns 'ing
these values in the
.Fa how
argument:
.Bl -tag -width ".Dv EXTEXIT_SIMPLE"
.It Dv EXTEXIT_SETINT
Set the integer variable pointer to by
.Fa addr
to the value of
.Fa status .
This is intended to enable other threads or processes to
detect the termination of the calling lwp or process.
.El
.Sh RETURN VALUES
The
.Fn extexit
function will only return if it was invoked
with invalid arguments.  In this case,
.Va errno
will be set to
.Er EINVAL .
In the case of a successful invocation,
.Fn extexit
will not return.
.Pp
In case of an error, the action specified in
.Fa how
will not be performed.
If an error occurs while performing an action, the results are
undefined.
However,
.Fn extexit
will try hard to avoid such a situation.
In any case, if an error occurs while performing an action,
.Fn extexit
will return.
.Sh SEE ALSO
.Xr _exit 2 ,
.Xr wait 2 ,
.Xr exit 3
.Sh HISTORY
The
.Fn extexit
function first appeared in
.Dx 1.9 .