.\"	$NetBSD: access.9,v 1.1 1996/06/16 10:38:35 pk Exp $
.\"
.\" Copyright (c) 1996 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Paul Kranenburg.
.\"
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.\" modification, are permitted provided that the following conditions
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.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"        This product includes software developed by the NetBSD
.\"        Foundation, Inc. and its contributors.
.\" 4. Neither the name of The NetBSD Foundation nor the names of its
.\"    contributors may be used to endorse or promote products derived
.\"    from this software without specific prior written permission.
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" $FreeBSD: src/share/man/man9/kernacc.9,v 1.7.2.4 2001/12/17 11:30:18 ru Exp $
.\" $DragonFly: src/share/man/man9/kernacc.9,v 1.2 2003/06/17 04:37:01 dillon Exp $
.\"
.Dd June 16, 1996
.Dt KERNACC 9
.Os
.Sh NAME
.Nm kernacc ,
.Nm useracc
.Nd check memory regions for accessibility
.Sh SYNOPSIS
.In sys/types.h
.In vm/vm.h
.In vm/vm_extern.h
.Ft int
.Fn kernacc "caddr_t addr" "int len" "int rw"
.Ft int
.Fn useracc "caddr_t addr" "int len" "int rw"
.Sh DESCRIPTION
The
.Fn kernacc
and
.Fn useracc
functions check whether operations of the type specified in
.Fa rw
are permitted in the range of virtual addresses given by
.Fa addr
and
.Fa len .
The possible values of
.Fa rw
are any bitwise combination of
.Dv VM_PROT_READ ,
.Dv VM_PROT_WRITE
and
.Dv VM_PROT_EXECUTE .
.Fn kernacc
checks addresses in the kernel address space, while
.Fn useracc
considers
.Fa addr
to represent an user space address.
The process context to use for this
operation is taken from the global variable
.Va curproc .
.Sh RETURN VALUES
Both functions return boolean true if the type of access specified
by
.Fa rw
is permitted.
Otherwise boolean false is returned.
.Sh BUGS
The process pointer should be passed in as an argument to
.Fn useracc .