minix/lib/libc/sys/posix_fadvise.2
Ben Gras 2fe8fb192f Full switch to clang/ELF. Drop ack. Simplify.
There is important information about booting non-ack images in
docs/UPDATING. ack/aout-format images can't be built any more, and
booting clang/ELF-format ones is a little different. Updating to the
new boot monitor is recommended.

Changes in this commit:

	. drop boot monitor -> allowing dropping ack support
	. facility to copy ELF boot files to /boot so that old boot monitor
	  can still boot fairly easily, see UPDATING
	. no more ack-format libraries -> single-case libraries
	. some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases
	. drop several ack toolchain commands, but not all support
	  commands (e.g. aal is gone but acksize is not yet).
	. a few libc files moved to netbsd libc dir
	. new /bin/date as minix date used code in libc/
	. test compile fix
	. harmonize includes
	. /usr/lib is no longer special: without ack, /usr/lib plays no
	  kind of special bootstrapping role any more and bootstrapping
	  is done exclusively through packages, so releases depend even
	  less on the state of the machine making them now.
	. rename nbsd_lib* to lib*
	. reduce mtree
2012-02-14 14:52:02 +01:00

102 lines
3.2 KiB
Groff

.\" $NetBSD: posix_fadvise.2,v 1.3 2009/06/09 11:21:33 yamt 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 June 9, 2009
.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 sys/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.