VOP_OPEN(9) MidnightBSD Kernel Developer’s Manual 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, struct file *fp);

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 accessed 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.

fp

The file being opened.

Pointer to the file fp is useful for file systems which require such information, e.g., fdescfs(5). Use ‘NULL’ as fp argument to VOP_OPEN() for in-kernel opens.

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.

RETURN VALUES

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

PSEUDOCODE

int
vop_open(struct vnode *vp, int mode, struct ucred *cred, struct thread *td,
struct file *fp)
{
/*
* 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.

MidnightBSD 0.3 June 5, 2007 MidnightBSD 0.3