/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright 2017 Nexenta Systems, Inc.  All rights reserved.
 */

/*	Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved	*/

/*
 * Portions of this source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */

#include <sys/param.h>
#include <sys/isa_defs.h>
#include <sys/types.h>
#include <sys/inttypes.h>
#include <sys/sysmacros.h>
#include <sys/cred.h>
#include <sys/dirent.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/vnode.h>
#include <sys/file.h>
#include <sys/mode.h>
#include <sys/uio.h>
#include <sys/filio.h>
#include <sys/debug.h>
#include <sys/kmem.h>
#include <sys/cmn_err.h>

/*
 * Returns count of dir entries, or -errno
 */
int
fake_getdents(vnode_t *vp, offset_t *offp, void *buf, size_t count)
{
	struct uio auio;
	struct iovec aiov;
	register int error;
	int sink;

	if (count < sizeof (struct dirent64))
		return (-EINVAL);

	/*
	 * Don't let the user overcommit kernel resources.
	 */
	if (count > MAXGETDENTS_SIZE)
		count = MAXGETDENTS_SIZE;

	if (vp->v_type != VDIR) {
		return (-ENOTDIR);
	}

	aiov.iov_base = buf;
	aiov.iov_len = count;
	auio.uio_iov = &aiov;
	auio.uio_iovcnt = 1;
	auio.uio_loffset = *offp;
	auio.uio_segflg = UIO_USERSPACE;
	auio.uio_resid = count;
	auio.uio_fmode = 0;
	auio.uio_extflg = UIO_COPY_CACHED;
	(void) VOP_RWLOCK(vp, V_WRITELOCK_FALSE, NULL);
	error = VOP_READDIR(vp, &auio, CRED(), &sink, NULL, 0);
	VOP_RWUNLOCK(vp, V_WRITELOCK_FALSE, NULL);
	if (error) {
		return (-error);
	}
	count = count - auio.uio_resid;
	*offp = auio.uio_loffset;

	return (count);
}