1.\" -*- nroff -*- 2.\" 3.\" Copyright (c) 1996 Doug Rabson 4.\" 5.\" All rights reserved. 6.\" 7.\" This program is free software. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 19.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 22.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28.\" 29.\" $FreeBSD$ 30.\" 31.Dd July 24, 1996 32.Dt VOP_RDWR 9 33.Os 34.Sh NAME 35.Nm VOP_READ , 36.Nm VOP_WRITE 37.Nd read or write a file 38.Sh SYNOPSIS 39.In sys/param.h 40.In sys/vnode.h 41.In sys/uio.h 42.Ft int 43.Fn VOP_READ "struct vnode *vp" "struct uio *uio" "int ioflag" "struct ucred *cred" 44.Ft int 45.Fn VOP_WRITE "struct vnode *vp" "struct uio *uio" "int ioflag" "struct ucred *cred" 46.Sh DESCRIPTION 47These entry points read or write the contents of a file. 48.Pp 49The arguments are: 50.Bl -tag -width ioflag 51.It Fa vp 52The vnode of the file. 53.It Fa uio 54The location of the data to be read or written. 55.It Fa ioflag 56Various flags. 57.It Fa cnp 58The credentials of the caller. 59.El 60.Pp 61The 62.Fa ioflag 63argument is used to give directives and hints to the file system. 64When attempting a read, the high 16 bits are used to provide a 65read-ahead hint (in units of file system blocks) that the file system 66should attempt. 67The low 16 bits are a bit mask which can contain 68the following flags: 69.Bl -tag -width "IO_NODELOCKED" 70.It Dv IO_UNIT 71Do I/O as atomic unit. 72.It Dv IO_APPEND 73Append write to end. 74.It Dv IO_SYNC 75Do I/O synchronously. 76.It Dv IO_NODELOCKED 77Underlying node already locked. 78.It Dv IO_NDELAY 79.Dv FNDELAY 80flag set in file table. 81.It Dv IO_VMIO 82Data already in VMIO space. 83.El 84.Sh LOCKS 85The file should be locked on entry and will still be locked on exit. 86Rangelock covering the whole i/o range should be owned around the call. 87.Sh RETURN VALUES 88Zero is returned on success, otherwise an error code is returned. 89.Sh ERRORS 90.Bl -tag -width Er 91.It Bq Er EFBIG 92An attempt was made to write a file that exceeds the process's file size 93limit or the maximum file size. 94.It Bq Er ENOSPC 95The file system is full. 96.It Bq Er EPERM 97An append-only flag is set on the file, but the caller is attempting to 98write before the current end of file. 99.El 100.Sh SEE ALSO 101.Xr uiomove 9 , 102.Xr vnode 9 103.Sh AUTHORS 104This manual page was written by 105.An Doug Rabson . 106