fs/ext2/dev.c

/*
 * (C) Copyright 2004
 *  esd gmbh <www.esd-electronics.com>
 *  Reinhard Arlt <reinhard.arlt@esd-electronics.com>
 *
 *  based on code of fs/reiserfs/dev.c by
 *
 *  (C) Copyright 2003 - 2004
 *  Sysgo AG, <www.elinos.com>, Pavel Bartusek <pba@sysgo.com>
 *
 *  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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */


#include <common.h>
#include <config.h>
#include <ext2fs.h>

static block_dev_desc_t *ext2fs_block_dev_desc;
static disk_partition_t part_info;

int ext2fs_set_blk_dev(block_dev_desc_t *rbdd, int part)
{
	ext2fs_block_dev_desc = rbdd;

	if (part == 0) {
		/* disk doesn't use partition table */
		part_info.start = 0;
		part_info.size = rbdd->lba;
		part_info.blksz = rbdd->blksz;
	} else {
		if (get_partition_info
		    (ext2fs_block_dev_desc, part, &part_info)) {
			return 0;
		}
	}
	return part_info.size;
}


int ext2fs_devread(int sector, int byte_offset, int byte_len, char *buf)
{
	ALLOC_CACHE_ALIGN_BUFFER(char, sec_buf, SECTOR_SIZE);
	unsigned sectors;

	/*
	 *  Check partition boundaries
	 */
	if ((sector < 0) ||
	    ((sector + ((byte_offset + byte_len - 1) >> SECTOR_BITS)) >=
		part_info.size)) {
		/* errnum = ERR_OUTSIDE_PART; */
		printf(" ** %s read outside partition sector %d\n",
		       __func__,
		       sector);
		return 0;
	}

	/*
	 *  Get the read to the beginning of a partition.
	 */
	sector += byte_offset >> SECTOR_BITS;
	byte_offset &= SECTOR_SIZE - 1;

	debug(" <%d, %d, %d>\n", sector, byte_offset, byte_len);

	if (ext2fs_block_dev_desc == NULL) {
		printf(" ** %s Invalid Block Device Descriptor (NULL)\n",
		       __func__);
		return 0;
	}

	if (byte_offset != 0) {
		/* read first part which isn't aligned with start of sector */
		if (ext2fs_block_dev_desc->
		    block_read(ext2fs_block_dev_desc->dev,
			       part_info.start + sector, 1,
			       (unsigned long *) sec_buf) != 1) {
			printf(" ** %s read error **\n", __func__);
			return 0;
		}
		memcpy(buf, sec_buf + byte_offset,
		       min(SECTOR_SIZE - byte_offset, byte_len));
		buf += min(SECTOR_SIZE - byte_offset, byte_len);
		byte_len -= min(SECTOR_SIZE - byte_offset, byte_len);
		sector++;
	}

	/*  read sector aligned part */
	sectors = byte_len / SECTOR_SIZE;

	if (sectors > 0) {
		if (ext2fs_block_dev_desc->block_read(
			ext2fs_block_dev_desc->dev,
			part_info.start + sector,
			sectors,
			(unsigned long *) buf) != sectors) {
			printf(" ** %s read error - block\n", __func__);
			return 0;
		}

		buf += sectors * SECTOR_SIZE;
		byte_len -= sectors * SECTOR_SIZE;
		sector += sectors;
	}

	if (byte_len != 0) {
		/* read rest of data which are not in whole sector */
		if (ext2fs_block_dev_desc->
		    block_read(ext2fs_block_dev_desc->dev,
			       part_info.start + sector, 1,
			       (unsigned long *) sec_buf) != 1) {
			printf(" ** %s read error - last part\n", __func__);
			return 0;
		}
		memcpy(buf, sec_buf, byte_len);
	}
	return 1;
}