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VOP_SETATTR
VOP_ATTRIB(9) FreeBSD Kernel Developer's Manual 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 modifica-
tion 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 attribute data via
*vap, otherwise an appropriate error is returned. VOP_SETATTR() returns
zero if the attributes were changed successfully, otherwise an appropri-
ate 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 != VNOVAL) ||
(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.
FreeBSD 6.2 July 24, 1996 FreeBSD 6.2
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