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.\" Copyright (c) 1996 Doug Rabson
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.Dd July 24, 1996
.Os
.Dt VOP_OPEN 9
.Sh NAME
.Nm VOP_OPEN ,
.Nm VOP_CLOSE
.Nd open or close a file
.Sh SYNOPSIS
.In sys/param.h
.In sys/vnode.h
.Ft int
.Fn VOP_OPEN "struct vnode *vp" "int mode" "struct ucred *cred" "struct proc *p"
.Ft int
.Fn VOP_CLOSE "struct vnode *vp" "int mode" "struct ucred *cred" "struct proc *p"
.Sh DESCRIPTION
The
.Xr VOP_OPEN 9
entry point is called before a file is accessed by a process and the
.Xr VOP_CLOSE 9
entry point is called after a file is finished with by the process.
.Pp
The arguments are:
.Bl -tag -width mode
.It Ar vp
the vnode of the file
.It Ar mode
the access mode required by the calling process
.It Ar p
the process which is accessing the file
.El
.Pp
The access mode is a set of flags, including
.Dv FREAD ,
.Dv FWRITE ,
.Dv O_NONBLOCK ,
.Dv O_APPEND .
.Sh LOCKS
.Xr VOP_OPEN 9
expects
.Fa vp
to be locked on entry and will leave it locked on return.
.Pp
.Xr VOP_CLOSE 9
expects at least a reference to be associated with the vnode and does not
care whether the vnode is locked or not.  The lock and reference state is
left unchanged on return.  Note that
.Fa vn_close
expects an unlocked, referenced vnode and will dereference the vnode prior
to returning.
.Sh RETURN VALUES
Zero is returned on success, otherwise an error code is returned.
.Sh PSEUDOCODE
.Bd -literal
int
vop_open(struct vnode *vp, int mode, struct ucred *cred, struct proc *p)
{
    /*
     * Most filesystems don't do much here.
     */
    return 0;
}
.Ed
.Sh SEE ALSO
.Xr vnode 9 ,
.Xr VOP_LOOKUP 9
.Sh AUTHORS
This man page was written by
.An Doug Rabson .