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VOP_OPEN (9) | Kernel routines | Unix Manual Pages | :man▋

NAME

VOP_OPEN, VOP_CLOSE - open or close a file

CONTENTS

Synopsis
Description
Locks
Implementation Notes
Return Values
Pseudocode
See Also
Authors

SYNOPSIS


.In sys/param.h
.In 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 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.

Additionally, VOP_OPEN can accept a file descriptor number in fdidx; this is useful for file systems which require such information, 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 returned.

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

 
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