.\" -*- nroff -*-
.\"
.\" Copyright (c) 2000 Jonathan M. Bresler
.\"
.\" All rights reserved.
.\"
.\" This program is free software.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd January 14, 2000
.Dt KASSERT 9
.Os
.Sh NAME
.Nm KASSERT
.Nd kernel expression verification macro
.Sh SYNOPSIS
.Cd "options INVARIANTS"
.Pp
.In sys/param.h
.In sys/systm.h
.Fn KASSERT expression msg
.Sh DESCRIPTION
In a kernel compiled with
.Cd "options INVARIANTS" ,
the
.Fn KASSERT
macro tests the given
.Fa expression
and if it is false,
calls the
.Xr panic 9
function, terminating the running system.
.Pp
In a kernel that does not have
.Cd "options INVARIANTS" ,
the
.Fn KASSERT
macro is defined to be a no-op.
The
second argument is a
.Xr printf 9
format string and its arguments,
enclosed in parentheses.
.Sh EXAMPLES
The kernel function
.Fn vput
must not be called with a
.Dv NULL
pointer.
.Bd -literal -offset indent
void
vput(vp)
        struct vnode *vp;
{
	struct proc *p = curproc;
	KASSERT(vp != NULL, ("vput: null vp"));
	...
}
.Ed
.Sh SEE ALSO
.Xr config 8 ,
.Xr panic 9
.Sh AUTHORS
This manual page was written by
.An Jonathan M. Bresler
.Aq jmb@FreeBSD.org .