freebsd-dev/share/man/man9/at_fork.9

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.\"
.\" Copyright (c) 1996 Julian Elischer
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.\" $Id: at_fork.9,v 1.5 1997/02/22 13:26:22 peter Exp $
.\" "
.Dd August 15, 1996
.Os
.Dt AT_FORK 9
.Sh NAME
.Nm at_fork ,
.Nm rm_at_fork
.Nd ask that a function be run at fork.
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/systm.h>
.Ft typedef void \*(lp*forklist_fn\*(rp \*(lpstruct proc*, struct proc*, int\*(rp;
.Ft int
.Fn at_fork "forklist_fn func"
.Ft int
.Fn rm_at_fork "forklist_fn func"
.Sh DESCRIPTION
The
.Nm at_fork
facility allows a kernel module to ensure that it is notified
at any process fork.
The function
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.Fa func
is called with the a pointer to the forking process's proc structure,
a pointer to the child's process structure and a flag word,
as used in
.Xr rfork 2
to indicate the type of fork.
.Pp
If the requirement for notification is removed, then the function
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.Fn rm_at_fork
must be called with the exact
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.Fa func
argument as the corresponding call to
.Fn at_fork .
.Pp
.Sh RETURN VALUES
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.Fn at_fork
returns an errno, 0 meaning success.
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.Fn rm_at_fork
returns the number of items removed (should be 0 or 1).
.Sh SEE ALSO
.Xr fork 2
.Sh HISTORY
The
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.Fn at_fork
function appeared in
.Fx 2.2 .
.Sh BUGS
Since the fork queue is not sorted
and items are added to the head, order of execution
is reversed to that of insertion.
.Sh AUTHORS
The function was written by
.ie Julian Elischer (julian@freebsd.org)
.el Julian Elischer (julian@freebsd.org)