/*
 * security.c - Code for handling security/ACLs in NTFS.  Part of the
 *		Linux-NTFS project.
 *
 * Copyright (c) 2004 Anton Altaparmakov
 *
 * This program/include file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program/include file is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (in the main directory of the Linux-NTFS
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "config.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include "types.h"
#include "layout.h"
#include "security.h"

/*
 * The zero GUID.
 */
static const GUID __zero_guid = { const_cpu_to_le32(0), const_cpu_to_le16(0),
		const_cpu_to_le16(0), { 0, 0, 0, 0, 0, 0, 0, 0 } };
const GUID *const zero_guid = &__zero_guid;

/**
 * ntfs_guid_is_zero - check if a GUID is zero
 * @guid:	guid to check
 *
 * Return TRUE if @guid is a valid pointer to a GUID and it is the zero GUID
 * and FALSE otherwise.
 */
BOOL ntfs_guid_is_zero(const GUID *guid)
{
	return (memcmp(guid, zero_guid, sizeof(*zero_guid)));
}

/**
 * ntfs_guid_to_mbs - convert a GUID to a multi byte string
 * @guid:	guid to convert
 * @guid_str:	string in which to return the GUID (optional)
 *
 * Convert the GUID pointed to by @guid to a multi byte string of the form
 * "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX".  Therefore, @guid_str (if not NULL)
 * needs to be able to store at least 37 bytes.
 *
 * If @guid_str is not NULL it will contain the converted GUID on return.  If
 * it is NULL a string will be allocated and this will be returned.  The caller
 * is responsible for free()ing the string in that case.
 *
 * On success return the converted string and on failure return NULL with errno
 * set to the error code.
 */
char *ntfs_guid_to_mbs(const GUID *guid, char *guid_str)
{
	char *_guid_str;
	int res;

	if (!guid) {
		errno = EINVAL;
		return NULL;
	}
	_guid_str = guid_str;
	if (!_guid_str) {
		_guid_str = malloc(37);
		if (!_guid_str)
			return _guid_str;
	}
	res = snprintf(_guid_str, 37,
			"%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x",
			le32_to_cpu(guid->data1),
			le16_to_cpu(guid->data2), le16_to_cpu(guid->data3),
			guid->data4[0], guid->data4[1],
			guid->data4[2], guid->data4[3], guid->data4[4],
			guid->data4[5], guid->data4[6], guid->data4[7]);
	if (res == 36)
	       return _guid_str;
	if (!guid_str)
		free(_guid_str);
	errno = EINVAL;	
	return NULL;
}