.\"	$NetBSD: revoke.2,v 1.3 1995/10/12 15:41:11 jtc Exp $
.\"
.\" Copyright (c) 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Berkeley Software Design, Inc.
.\"
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.\" modification, are permitted provided that the following conditions
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.\"    must display the following acknowledgement:
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.\"	California, Berkeley and its contributors.
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.\"     @(#)revoke.2	8.1 (Berkeley) 6/4/93
.\"
.Dd June 4, 1993
.Dt REVOKE 2
.Os
.Sh NAME
.Nm revoke
.Nd revoke file access
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fn revoke "const char *path"
.Sh DESCRIPTION
The
.Nm revoke
function invalidates all current open file descriptors in the system
for the file named by
.Fa path .
Subsequent operations on any such descriptors
fail, with the exceptions that a
.Fn read
from a character device file which has been revoked
returns a count of zero (end of file),
and a
.Fn close
call will succeed.
If the file is a special file for a device which is open,
the device close function
is called as if all open references to the file had been closed.
.Pp
Access to a file may be revoked only by its owner or the super user.
The
.Nm revoke
function is currently supported only for block and character special
device files.
It is normally used to prepare a terminal device for a new login session,
preventing any access by a previous user of the terminal.
.Sh RETURN VALUES
A 0 value indicated that the call succeeded.  A \-1 return value
indicates an error occurred and
.Va errno
is set to indicated the reason.
.Sh ERRORS
Access to the named file is revoked unless one of the following:
.Bl -tag -width Er
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded 255 characters,
or an entire path name exceeded 1024 characters.
.It Bq Er ENOENT
The named file or a component of the path name does not exist.
.It Bq Er EACCES
Search permission is denied for a component of the path prefix.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er EFAULT
.Fa Path
points outside the process's allocated address space.
.It Bq Er EINVAL
The named file is neither a character special or block
special file.
.It Bq Er EPERM
The caller is neither the owner of the file nor the super user.
.It Bq Er ENOTSUP
The path does not represent a block or character device.
.It Bq Er EBUSY
The path represents a block device which is providing the backing for a mounted volume. 
.El
.Sh SEE ALSO
.Xr close 2
.Sh HISTORY
The
.Nm revoke
function was introduced in
.Bx 4.3 Reno .