vop_open(9)

NAME

VOP_OPEN, VOP_CLOSE - open or close a file

SYNOPSIS

#include <sys/param.h>
#include <sys/vnode.h>
int
VOP_OPEN(struct vnode *vp, int mode, struct ucred *cred,
        struct thread *td, int fdidx);
int
VOP_CLOSE(struct vnode *vp, int mode, struct ucred *cred,
        struct thread *td);

DESCRIPTION

The VOP_OPEN() entry point is called before a file is ac

cessed by a process and the VOP_CLOSE() entry point is called after a file

is finished
with by the process.

The arguments are:

vp The vnode of the file.

mode The access mode required by the calling process.

td The thread which is accessing the file.

Additionally, VOP_OPEN() can accept a file descriptor number

in fdidx;
this is useful for file systems which require such informa

tion, e.g.,
fdescfs(5).

The access mode is a set of flags, including FREAD, FWRITE,

O_NONBLOCK,
O_APPEND.

LOCKS

VOP_OPEN() expects vp to be locked on entry and will leave

it locked on
return.

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

vn_close expects an
unlocked, referenced vnode and will dereference the vnode

prior to
returning.

IMPLEMENTATION NOTES

The fdidx argument to VOP_OPEN() is currently unused, use

`-1' for the
meantime; however, this will change in future.

RETURN VALUES

Zero is returned on success, otherwise an error code is re

turned.

PSEUDOCODE

int
vop_open(struct vnode *vp, int mode, struct ucred *cred,

struct thread *td)
{

/*

* Most file systems don't do much here.
*/

return 0;

}

SEE ALSO

vnode(9), VOP_LOOKUP(9)

AUTHORS

This manual page was written by Doug Rabson.

BSD July 24, 1996

BSD