u-boot/fs/ext2/dev.c
Anton Staaf d961c188b2 ext2: Simplify partial sector access logic
Previously reading or writing zero full sectors (reading the end of
one sector and the beginning of the next for example) was special
cased and involved stack allocating a second sector buffer.  This
change uses the same code path for this case as well as when there
are a non-zero number of full sectors to access.  The result is
easier to read and reduces the maximum stack used.

Signed-off-by: Anton Staaf <robotboy@chromium.org>
Cc: Andy Fleming <afleming@freescale.com>
Acked-by: Detlev Zundel <dzu@denx.de>
2011-07-28 15:36:32 +02:00

131 lines
3.4 KiB
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 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;
}