.\"	$NetBSD: fhopen.2,v 1.1 1999/06/30 01:32:15 wrstuden Exp $
.\"
.\" Copyright (c) 1999 National Aeronautics & Space Administration
.\" All rights reserved.
.\"
.\" This software was written by William Studenmund of the
.\" Numerical Aerospace Simulation Facility, NASA Ames Research Center.
.\"
.\" 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.
.\" 3. Neither the name of the National Aeronautics & Space Administration
.\"    nor the names of its contributors may be used to endorse or promote
.\"    products derived from this software without specific prior written
.\"    permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NATIONAL AERONAUTICS & SPACE ADMINISTRATION
.\" ``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 ADMINISTRATION OR CONTRIB-
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.\" OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\"
.\" $FreeBSD: head/lib/libc/sys/fhopen.2 147700 2005-06-30 13:18:15Z hmp $
.\"
.Dd June 29, 1999
.Dt FHOPEN 2
.Os
.Sh NAME
.Nm fhopen ,
.Nm fhstat ,
.Nm fhstatfs
.Nd access file via file handle
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/param.h
.In sys/mount.h
.In sys/stat.h
.Ft int
.Fn fhopen "const fhandle_t *fhp" "int flags"
.Ft int
.Fn fhstat "const fhandle_t *fhp" "struct stat *sb"
.Ft int
.Fn fhstatfs "const fhandle_t *fhp" "struct statfs *buf"
.Sh DESCRIPTION
These system calls provide a means to access a file given the file handle
.Fa fhp .
As this method bypasses directory access restrictions, these calls are
restricted to the superuser.
.Pp
The
.Fn fhopen
system call
opens the file referenced by
.Fa fhp
for reading and/or writing as specified by the argument
.Fa flags
and returns the file descriptor to the calling process.
The
.Fa flags
argument
is specified by
.Em or Ns 'ing
together the flags used for the
.Xr open 2
system call.
All said flags are valid except for
.Dv O_CREAT .
.Pp
The
.Fn fhstat
and
.Fn fhstatfs
system calls
provide the functionality of the
.Xr fstat 2
and
.Xr fstatfs 2
calls except that they return information for the file referred to by
.Fa fhp
rather than an open file.
.Sh RETURN VALUES
Upon successful completion,
.Fn fhopen
returns the file descriptor for the opened file;
otherwise the value \-1 is returned and the global variable
.Va errno
is set to indicate the error.
.Pp
.Rv -std fhstat fhstatfs
.Sh ERRORS
In addition to the errors returned by
.Xr open 2 ,
.Xr fstat 2 ,
and
.Xr fstatfs 2
respectively,
.Fn fhopen ,
.Fn fhstat ,
and
.Fn fhstatfs
will return
.Bl -tag -width Er
.It Bq Er EINVAL
Calling
.Fn fhopen
with
.Dv O_CREAT
set.
.It Bq Er ESTALE
The file handle
.Fa fhp
is no longer valid.
.El
.Sh SEE ALSO
.Xr fstat 2 ,
.Xr fstatfs 2 ,
.Xr getfh 2 ,
.Xr open 2
.Sh HISTORY
The
.Fn fhopen ,
.Fn fhstat ,
and
.Fn fhstatfs
system calls first appeared in
.Nx 1.5
and were adapted to
.Fx 4.0
by
.An Alfred Perlstein .
.Sh AUTHORS
This manual page was written by
.An William Studenmund
for
.Nx .