.\"
.\" Copyright (c) 2001 Dima Dorfman <dd@FreeBSD.org>
.\" All rights reserved.
.\"
.\" 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 AUTHOR AND CONTRIBUTORS ``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 AUTHOR OR CONTRIBUTORS 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 June 24, 2001
.Dt EXTATTR 3
.Os
.Sh NAME
.Nm extattr_namespace_to_string ,
.Nm extattr_string_to_namespace
.Nd convert an extended attribute namespace identifier to a string and
vice versa
.Sh LIBRARY
.Lb libutil
.Sh SYNOPSIS
.In sys/extattr.h
.In libutil.h
.Ft int
.Fn extattr_namespace_to_string "int attrnamespace" "char **string"
.Ft int
.Fn extattr_string_to_namespace "const char *string" "int *attrnamespace"
.Sh DESCRIPTION
The
.Fn extattr_namespace_to_string
function converts a VFS extended attribute identifier to a human-readable
string;
the
.Fn extattr_string_to_namespace
function undoes the aforementioned operation,
and converts a human-readable string representing a namespace to a
namespace identifier.
Although a file system may implement arbitrary namespaces,
these functions only support the
.Dv EXTATTR_NAMESPACE_USER
.Pq Dq user
and
.Dv EXTATTR_NAMESPACE_SYSTEM
.Pq Dq system
namespaces,
which are defined in
.Xr extattr 9 .
.Pp
These functions are meant to be used in error reporting and other
interactive tasks.
For example,
instead of printing the integer identifying an extended attribute in
an error message,
a program might use
.Fn extattr_namespace_to_string
to obtain a human-readable representation.
Likewise,
instead of requiring a user to enter the integer representing a namespace,
an interactive program might ask for a name and use
.Fn extattr_string_to_namespace
to get the desired identifier.
.Sh RETURN VALUES
If any of the calls are unsuccessful, the value \-1 is returned
and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EINVAL
The requested namespace could not be identified.
.El
.Sh SEE ALSO
.Xr extattr 2 ,
.Xr getextattr 8 ,
.Xr setextattr 8 ,
.Xr extattr 9
.Sh HISTORY
Extended attribute support was developed as part of the
.Tn TrustedBSD
Project, and introduced in
.Fx 5.0 .
It was developed to support security extensions requiring additional labels
to be associated with each file or directory.