freebsd-skq/share/man/man9/at_fork.9
2001-04-18 15:54:10 +00:00

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.\" Copyright (c) 1996 Julian Elischer
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.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" ( *forklist_fn )
.Fa ( "struct proc*" , "struct proc*" , int ) ;
.Pp
.Ft int
.Fn at_fork "forklist_fn func"
.Ft int
.Fn rm_at_fork "forklist_fn func"
.Sh DESCRIPTION
The
.Nm
facility allows a kernel module to ensure that it is notified
at any process fork.
The function
.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
.Fn rm_at_fork
must be called with the exact
.Fa func
argument as the corresponding call to
.Fn at_fork .
.Pp
.Sh RETURN VALUES
.Fn at_fork
returns an errno, 0 meaning success.
.Fn rm_at_fork
returns the number of items removed (should be 0 or 1).
.Sh SEE ALSO
.Xr fork 2
.Sh HISTORY
The
.Fn at_fork
function appeared in
.Fx 2.2 .
.Sh AUTHORS
The function was written by
.An Julian Elischer Aq julian@FreeBSD.org .