minix/lib/libc/sys/posix_fadvise.2
Lionel Sambuc 84d9c625bf Synchronize on NetBSD-CVS (2013/12/1 12:00:00 UTC)
- Fix for possible unset uid/gid in toproto
 - Fix for default mtree style
 - Update libelf
 - Importing libexecinfo
 - Resynchronize GCC, mpc, gmp, mpfr
 - build.sh: Replace params with show-params.
     This has been done as the make target has been renamed in the same
     way, while a new target named params has been added. This new
     target generates a file containing all the parameters, instead of
     printing it on the console.
 - Update test48 with new etc/services (Fix by Ben Gras <ben@minix3.org)
     get getservbyport() out of the inner loop

Change-Id: Ie6ad5226fa2621ff9f0dee8782ea48f9443d2091
2014-07-28 17:05:06 +02:00

102 lines
3.1 KiB
Groff

.\" $NetBSD: posix_fadvise.2,v 1.5 2013/02/04 20:03:11 wiz Exp $
.\"
.\" Copyright (c)2006,2009 YAMAMOTO Takashi,
.\" 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.
.\"
.\" ------------------------------------------------------------
.Dd February 4, 2013
.Dt POSIX_FADVISE 2
.Os
.Sh NAME
.Nm posix_fadvise
.Nd hint at the future access pattern of a file
.\" ------------------------------------------------------------
.Sh LIBRARY
.Lb libc
.\" ------------------------------------------------------------
.Sh SYNOPSIS
.In fcntl.h
.Ft int
.Fn posix_fadvise "int fd" "off_t offset" "off_t size" "int hint"
.\" ------------------------------------------------------------
.Sh DESCRIPTION
.Fn posix_fadvise
hints at the application's access pattern to the file and range
given by
the file descriptor,
.Fa fd ,
and
.Fa offset
and
.Fa size .
If
.Fa size
is zero, it means to the end of file.
.Pp
.Fa hint
should be one of the followings.
.Pp
.Bl -tag -offset indent -width POSIX_FADV_SEQUENTIAL -compact
.It POSIX_FADV_NORMAL
No hint.
(default)
.It POSIX_FADV_RANDOM
Random access.
.It POSIX_FADV_SEQUENTIAL
Sequential access.
(from lower offset to higher offset.)
.It POSIX_FADV_WILLNEED
Will be accessed.
.It POSIX_FADV_DONTNEED
Will not be accessed.
.It POSIX_FADV_NOREUSE
Will be accessed just once.
.El
.Pp
Calling
.Fn posix_fadvise
doesn't alter the semantics of the operations,
it is only a matter of performance.
.\" ------------------------------------------------------------
.Sh RETURN VALUES
On success,
.Fn posix_fadvise
returns 0.
Otherwise, it returns an error number.
.\" ------------------------------------------------------------
.Sh SEE ALSO
.Xr errno 2 ,
.Xr madvise 2
.\" ------------------------------------------------------------
.Sh BUGS
For
.Dv POSIX_FADV_NORMAL ,
.Dv POSIX_FADV_RANDOM ,
and
.Dv POSIX_FADV_SEQUENTIAL ,
the current implementation ignores
.Fa offset
and
.Fa size ,
and applies the hint to the whole file.