freebsd-dev/share/man/man9/VOP_OPENCLOSE.9
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.\" -*- nroff -*-
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.\" Copyright (c) 1996 Doug Rabson
.\"
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.\" $FreeBSD$
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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 thread *td" "int fdidx"
.Ft int
.Fn VOP_CLOSE "struct vnode *vp" "int mode" "struct ucred *cred" "struct thread *td"
.Sh DESCRIPTION
The
.Fn VOP_OPEN
entry point is called before a file is accessed by a process and the
.Fn VOP_CLOSE
entry point is called after a file is finished with by the process.
.Pp
The arguments are:
.Bl -tag -width mode
.It Fa vp
the vnode of the file
.It Fa mode
the access mode required by the calling process
.It Fa td
the thread which is accessing the file
.El
.Pp
Additionally,
.Fn VOP_OPEN
can accept a file descriptor number in
.Fa fdidx ;
this is useful for file systems which require such information, e.g.,
.Xr fdesc 5 .
.Pp
The access mode is a set of flags, including
.Dv FREAD ,
.Dv FWRITE ,
.Dv O_NONBLOCK ,
.Dv O_APPEND .
.Sh LOCKS
.Fn VOP_OPEN
expects
.Fa vp
to be locked on entry and will leave it locked on return.
.Pp
.Fn VOP_CLOSE
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 IMPLEMENTATION NOTES
The
.Fa fdidx
argument to
.Fn VOP_OPEN
is currently unused, use
.Ql \-1
for the meantime; however, this will change in future.
.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 thread *td)
{
/*
* Most file systems 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 .