vop_attrib(9)

NAME

VOP_GETATTR, VOP_SETATTR - get and set attributes on a file

or directory

SYNOPSIS

#include <sys/param.h>
#include <sys/vnode.h>
int
VOP_GETATTR(struct  vnode  *vp,  struct  vattr  *vap, struct
ucred *cred,
        struct thread *td);
int
VOP_SETATTR(struct vnode  *vp,  struct  vattr  *vap,  struct
ucred *cred,
        struct thread *td);

DESCRIPTION

These entry points manipulate various attributes of a file

or directory,
including file permissions, owner, group, size, access time

and modification time.

The arguments are:

vp The vnode of the file.

vap The attributes of the file.

cred The user credentials of the calling process.

td The thread.

Attributes which are not being modified by VOP_SETATTR()

should be set to
the value VNOVAL; VATTR_NULL() may be used to clear all the

values, and
should generally be used to reset the contents of *vap prior

to setting
specific values.

LOCKS

VOP_GETATTR() expects the vnode to be locked on entry and

will leave the
vnode locked on return. The lock type can be either shared

or exclusive.

VOP_SETATTR() expects the vnode to be locked on entry and

will leave the
vnode locked on return. The lock type must be exclusive.

RETURN VALUES

VOP_GETATTR() returns 0 if it was able to retrieve the at

tribute data via
*vap, otherwise an appropriate error is returned.

VOP_SETATTR

zero if the attributes were changed successfully, otherwise

an appropriate error is returned.

PSEUDOCODE

int
vop_getattr(struct vnode *vp, struct vattr *vap,

struct ucred *cred, struct thread *td)

{

/*

* Fill in the contents of *vap with information from
* the file system.
*/

...;

return 0;

}

int
vop_setattr(struct vnode *vp, struct vattr *vap,

struct ucred *cred, struct thread *td)

{

/*

* Check for unsettable attributes.
*/

if ((vap->va_type != VNON) || (vap->va_nlink != VNOVAL)

(vap->va_fsid != VNOVAL) || (vap->va_fileid != VNO

VAL)
(vap->va_blocksize != VNOVAL) || (vap->va_rdev !=

VNOVAL)
((int)vap->va_bytes != VNOVAL) || (vap->va_gen !=

VNOVAL)) {
return (EINVAL);

}

if (vap->va_flags != VNOVAL) {

/*

* Set the immutable and append flags of the file.
*/

}

if (vap->va_uid != (uid_t)VNOVAL || vap->va_gid !=

(gid_t)VNOVAL) {

/*

* Change owner and/or group of the file.
*/

}

if (vap->va_size != VNOVAL) {

/*

* Truncate the file to the specified size.
*/

}

if (vap->va_atime.tv_sec != VNOVAL

vap->va_mtime.tv_sec != VNOVAL) {

/*

* Change access and/or modification time of file.
*/

}

if (vap->va_mode != (mode_t)VNOVAL) {

/*

* Change permissions of file.
*/

}

return 0;

}

ERRORS

[EPERM] The file is immutable.

[EACCES] The caller does not have permission to

modify the file

or directory attributes.

[EROFS] The file system is read-only.

SEE ALSO

VFS(9), vnode(9), VOP_ACCESS(9)

AUTHORS

This manual page was written by Doug Rabson.

BSD July 24, 1996

BSD