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) {
	char sec_buf[SECTOR_SIZE];
	unsigned block_len;

/*
 *  Check partition boundaries
 */
	if ((sector < 0)
	    || ((sector + ((byte_offset + byte_len - 1) >> SECTOR_BITS)) >=
		part_info.size)) {
	/*      errnum = ERR_OUTSIDE_PART; */
		printf (" ** ext2fs_devread() read outside partition sector %d\n", 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 ("** Invalid Block Device Descriptor (NULL)\n");
		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 (" ** ext2fs_devread() read error **\n");
			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++;
	}

	if (byte_len == 0)
		return 1;

	/*  read sector aligned part */
	block_len = byte_len & ~(SECTOR_SIZE - 1);

	if (block_len == 0) {
		u8 p[SECTOR_SIZE];

		block_len = SECTOR_SIZE;
		ext2fs_block_dev_desc->block_read(ext2fs_block_dev_desc->dev,
						  part_info.start + sector,
						  1, (unsigned long *)p);
		memcpy(buf, p, byte_len);
		return 1;
	}

	if (ext2fs_block_dev_desc->block_read (ext2fs_block_dev_desc->dev,
					       part_info.start + sector,
					       block_len / SECTOR_SIZE,
					       (unsigned long *) buf) !=
	    block_len / SECTOR_SIZE) {
		printf (" ** ext2fs_devread() read error - block\n");
		return (0);
	}
	block_len = byte_len & ~(SECTOR_SIZE - 1);
	buf += block_len;
	byte_len -= block_len;
	sector += block_len / SECTOR_SIZE;

	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 (" ** ext2fs_devread() read error - last part\n");
			return (0);
		}
		memcpy (buf, sec_buf, byte_len);
	}
	return (1);
}