cbm.c

/*
	cbm.c (09.11.10)
	Clusters Bitmap creation code.

	Free exFAT implementation.
	Copyright (C) 2011-2018  Andrew Nayenko

	This program 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 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; if not, write to the Free Software Foundation, Inc.,
	51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include "cbm.h"
#include "fat.h"
#include "uct.h"
#include "rootdir.h"
#include <limits.h>
#include <string.h>

static off_t cbm_alignment(void)
{
	return get_cluster_size();
}

static off_t cbm_size(void)
{
	return DIV_ROUND_UP(
			(get_volume_size() - get_position(&cbm)) / get_cluster_size(),
			CHAR_BIT);
}

static int cbm_write(struct exfat_dev* dev)
{
	uint32_t allocated_clusters =
			DIV_ROUND_UP(cbm.get_size(), get_cluster_size()) +
			DIV_ROUND_UP(uct.get_size(), get_cluster_size()) +
			DIV_ROUND_UP(rootdir.get_size(), get_cluster_size());
	size_t bitmap_size = ROUND_UP(allocated_clusters, CHAR_BIT);
	bitmap_t* bitmap = malloc(BMAP_SIZE(bitmap_size));
	size_t i;

	if (bitmap == NULL)
	{
		exfat_error("failed to allocate bitmap of %zu bytes",
				BMAP_SIZE(bitmap_size));
		return 1;
	}
	memset(bitmap, 0, BMAP_SIZE(bitmap_size));

	for (i = 0; i < bitmap_size; i++)
		if (i < allocated_clusters)
			BMAP_SET(bitmap, i);
	if (exfat_write(dev, bitmap, bitmap_size / CHAR_BIT) < 0)
	{
		free(bitmap);
		exfat_error("failed to write bitmap of %zu bytes",
				bitmap_size / CHAR_BIT);
		return 1;
	}
	free(bitmap);
	return 0;
}

const struct fs_object cbm =
{
	.get_alignment = cbm_alignment,
	.get_size = cbm_size,
	.write = cbm_write,
};