aa12cea2cc
Although groff_mdoc(7) gives another impression, this is the ordering most widely used and also required by mdocml/mandoc. Reviewed by: ru Approved by: philip, ed (mentors)
105 lines
3.2 KiB
Groff
105 lines
3.2 KiB
Groff
.\" -*- nroff -*-
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.\"
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.\" Copyright (c) 1996 Doug Rabson
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.\"
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.\" All rights reserved.
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.\"
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.\" This program is free software.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd July 24, 1996
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.Dt VOP_RDWR 9
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.Os
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.Sh NAME
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.Nm VOP_READ ,
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.Nm VOP_WRITE
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.Nd read or write a file
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.Sh SYNOPSIS
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.In sys/param.h
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.In sys/vnode.h
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.In sys/uio.h
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.Ft int
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.Fn VOP_READ "struct vnode *vp" "struct uio *uio" "int ioflag" "struct ucred *cred"
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.Ft int
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.Fn VOP_WRITE "struct vnode *vp" "struct uio *uio" "int ioflag" "struct ucred *cred"
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.Sh DESCRIPTION
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These entry points read or write the contents of a file
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.Pp
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The arguments are:
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.Bl -tag -width ioflag
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.It Fa vp
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The vnode of the file.
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.It Fa uio
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The location of the data to be read or written.
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.It Fa ioflag
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Various flags.
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.It Fa cnp
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The credentials of the caller.
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.El
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.Pp
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The
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.Fa ioflag
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argument is used to give directives and hints to the file system.
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When attempting a read, the high 16 bits are used to provide a
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read-ahead hint (in units of file system blocks) that the file system
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should attempt.
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The low 16 bits are a bit mask which can contain
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the following flags:
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.Bl -tag -width ".Dv IO_NODELOCKED"
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.It Dv IO_UNIT
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Do I/O as atomic unit.
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.It Dv IO_APPEND
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Append write to end.
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.It Dv IO_SYNC
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Do I/O synchronously.
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.It Dv IO_NODELOCKED
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Underlying node already locked.
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.It Dv IO_NDELAY
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.Dv FNDELAY
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flag set in file table.
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.It Dv IO_VMIO
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Data already in VMIO space.
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.El
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.Sh LOCKS
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The file should be locked on entry and will still be locked on exit.
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.Sh RETURN VALUES
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Zero is returned on success, otherwise an error code is returned.
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.Sh ERRORS
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.Bl -tag -width Er
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.It Bq Er EFBIG
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An attempt was made to write a file that exceeds the process's file size
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limit or the maximum file size.
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.It Bq Er ENOSPC
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The file system is full.
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.It Bq Er EPERM
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An append-only flag is set on the file, but the caller is attempting to
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write before the current end of file.
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.El
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.Sh SEE ALSO
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.Xr uiomove 9 ,
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.Xr vnode 9
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.Sh AUTHORS
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This manual page was written by
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.An Doug Rabson .
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