freebsd-skq/lib/libc/sys/fhopen.2

.\"	$NetBSD: fhopen.2,v 1.1 1999/06/30 01:32:15 wrstuden Exp $
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.\" This software was written by William Studenmund of the
.\" Numerical Aerospace Simulation Facility, NASA Ames Research Center.
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.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is no longer valid.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 .