freebsd-dev/share/man/man9/VOP_ATTRIB.9

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.\" Copyright (c) 1996 Doug Rabson
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.\" $Id: VOP_ATTRIB.9,v 1.4 1997/03/07 03:32:21 mpp Exp $
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.Dd July 24, 1996
.Os
.Dt VOP_ATTRIB 9
.Sh NAME
.Nm VOP_GETATTR ,
.Nm VOP_SETATTR
.Nd get and set attributes on a file or directory
.Sh SYNOPSIS
.Fd #include <sys/param.h>
.Fd #include <sys/vnode.h>
.Ft int
.Fn VOP_GETATTR "struct vnode *vp" "struct vattr *vap" "struct ucred *cred" "struct proc *p"
.Ft int
.Fn VOP_SETATTR "struct vnode *vp" "struct vattr *vap" "struct ucred *cred" "struct proc *p"
.Sh DESCRIPTION
These entry points manipulate various attributes of a file or directory,
including file permissions, owner, group, size,
access time and modification time.
.Pp
The arguments are:
.Bl -tag -width cred
.It Ar vp
the vnode of the file
.It Ar vpp
the attributes of the file
.It Ar cred
the user credentials of the calling process
.It Ar p
the process
.El
.Pp
Attributes which are not being modified by
.Xr VOP_SETATTR 9
should be set to the value
.Dv VNOVAL .
.Sh LOCKS
The file should not be locked on entry.
.Sh RETURN VALUES
.Xr VOP_GETATTR 9
returns information about the file in
.Fa *vap .
.Xr VOP_SETATTR 9
returns zero if the attributes were changed successfully, otherwise an
appropriate error is returned.
.Sh PSEUDOCODE
.Bd -literal
int
vop_getattr(struct vnode *vp, struct vattr *vpp,
	    struct ucred *cred, struct proc *p)
{
    /*
     * Fill in the contents of *vpp with information from
     * the filesystem.
     */
    ...;

    return 0;
}

int
vop_setattr(struct vnode *vp, struct vattr *vpp,
	    struct ucred *cred, struct proc *p)
{
    /*
     * 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;
}
.Ed
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EPERM
The file is immutable
.It Bq Er EACCES
Permission denied
.It Bq Er EROFS
The filesystem is readonly
.El
.Sh SEE ALSO
.Xr vnode 9 ,
.Xr VOP_ACCESS 9
.Sh AUTHORS
This man page was written by Doug Rabson.