.\"	$NetBSD: fdatasync.2,v 1.1 1998/06/05 20:48:59 kleink Exp $
.\"
.\" Copyright (c) 1998 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Klaus Klein.
.\"
.\" 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. 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.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
.\"
.Dd May 30, 1998
.Dt FDATASYNC 2
.Os NetBSD 1.4
.Sh NAME
.Nm fdatasync
.Nd synchronise the data of a file
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fn fdatasync "int filedes"
.Sh DESCRIPTION
The
.Fn fdatasync
function forces all currently queued I/O operations associated with
the file indicated by the file descriptor
.Fa filedes
to the synchronised I/O completition state.
.Pp
The functionality is as described for
.Xr fsync 2 ,
with the exception that all I/O  operations are completed as defined
for synchronised I/O data integrity completion.
.Pp
.Sh RETURN VALUES
If successful, the
.Fn fdatasync
function returns the value 0.  Otherwise, the function returns the
value -1 and sets
.Dv errno
to indicate the error. If the
.Fn fdatasync
function fails, outstanding I/O operations are not
guaranteed to have been completed.
.Sh ERRORS
The
.Fn fdatasync
function will fail if:
.Bl -tag -width Er
.It Bq Er EBADF
The
.Fa filedes
argument is not a valid file descriptor.
.It Bq Er EINVAL
This implementation does not support syncronised I/O for this file.
.It Bq Er ENOSYS
The function
.Fn fdatasync
is not supported by this implementation.
.El
.Pp
In the event that any of the queued I/O operations fail,
.Fn fdatasync
returns the eror conditions defined for
.Xr read 2
and
.Xr write 2 .
.Sh SEE ALSO
.Xr fsync 2 ,
.Xr open 2 ,
.Xr read 2 ,
.Xr write 2
.Sh STANDARDS
The
.Fn fdatasync
function conforms to
.St -p1003.1b-93 .