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115 lines
3.3 KiB
Groff
115 lines
3.3 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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.Os
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.Dt VOP_OPEN 9
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.Sh NAME
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.Nm VOP_OPEN ,
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.Nm VOP_CLOSE
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.Nd open or close 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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.Ft int
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.Fn VOP_OPEN "struct vnode *vp" "int mode" "struct ucred *cred" "struct thread *td" "int fdidx"
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.Ft int
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.Fn VOP_CLOSE "struct vnode *vp" "int mode" "struct ucred *cred" "struct thread *td"
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.Sh DESCRIPTION
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The
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.Fn VOP_OPEN
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entry point is called before a file is accessed by a process and the
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.Fn VOP_CLOSE
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entry point is called after a file is finished with by the process.
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.Pp
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The arguments are:
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.Bl -tag -width mode
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.It Fa vp
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The vnode of the file.
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.It Fa mode
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The access mode required by the calling process.
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.It Fa td
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The thread which is accessing the file.
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.El
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.Pp
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Additionally,
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.Fn VOP_OPEN
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can accept a file descriptor number in
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.Fa fdidx ;
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this is useful for file systems which require such information, e.g.,
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.Xr fdescfs 5 .
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.Pp
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The access mode is a set of flags, including
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.Dv FREAD ,
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.Dv FWRITE ,
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.Dv O_NONBLOCK ,
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.Dv O_APPEND .
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.Sh LOCKS
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.Fn VOP_OPEN
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expects
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.Fa vp
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to be locked on entry and will leave it locked on return.
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.Pp
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.Fn VOP_CLOSE
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expects at least a reference to be associated with the vnode and does not
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care whether the vnode is locked or not.
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The lock and reference state is left unchanged on return.
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Note that
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.Fa vn_close
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expects an unlocked, referenced vnode and will dereference the vnode prior
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to returning.
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.Sh IMPLEMENTATION NOTES
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The
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.Fa fdidx
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argument to
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.Fn VOP_OPEN
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is currently unused, use
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.Ql \-1
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for the meantime; however, this will change in future.
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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 PSEUDOCODE
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.Bd -literal
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int
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vop_open(struct vnode *vp, int mode, struct ucred *cred, struct thread *td)
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{
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/*
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* Most file systems don't do much here.
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*/
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return 0;
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}
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.Ed
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.Sh SEE ALSO
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.Xr vnode 9 ,
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.Xr VOP_LOOKUP 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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