- unsigned block_len;
- int log2blksz = ext4fs_block_dev_desc->log2blksz;
- ALLOC_CACHE_ALIGN_BUFFER(char, sec_buf, (ext4fs_block_dev_desc ?
- ext4fs_block_dev_desc->blksz :
- 0));
- if (ext4fs_block_dev_desc == NULL) {
- printf("** Invalid Block Device Descriptor (NULL)\n");
- return 0;
- }
-
- /* Check partition boundaries */
- if ((sector < 0) ||
- ((sector + ((byte_offset + byte_len - 1) >> log2blksz))
- >= part_info->size)) {
- printf("%s read outside partition %d\n", __func__, sector);
- return 0;
- }
-
- /* Get the read to the beginning of a partition */
- sector += byte_offset >> log2blksz;
- byte_offset &= ext4fs_block_dev_desc->blksz - 1;
-
- debug(" <%d, %d, %d>\n", sector, byte_offset, byte_len);
-
- if (byte_offset != 0) {
- /* read first part which isn't aligned with start of sector */
- if (ext4fs_block_dev_desc->
- block_read(ext4fs_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(ext4fs_block_dev_desc->blksz
- - byte_offset, byte_len));
- buf += min(ext4fs_block_dev_desc->blksz
- - byte_offset, byte_len);
- byte_len -= min(ext4fs_block_dev_desc->blksz
- - byte_offset, byte_len);
- sector++;
- }
-
- if (byte_len == 0)
- return 1;
-
- /* read sector aligned part */
- block_len = byte_len & ~(ext4fs_block_dev_desc->blksz - 1);
-
- if (block_len == 0) {
- ALLOC_CACHE_ALIGN_BUFFER(u8, p, ext4fs_block_dev_desc->blksz);
-
- block_len = ext4fs_block_dev_desc->blksz;
- ext4fs_block_dev_desc->block_read(ext4fs_block_dev_desc->dev,
- part_info->start + sector,
- 1, (unsigned long *)p);
- memcpy(buf, p, byte_len);
- return 1;
- }
-
- if (ext4fs_block_dev_desc->block_read(ext4fs_block_dev_desc->dev,
- part_info->start + sector,
- block_len >> log2blksz,
- (unsigned long *) buf) !=
- block_len >> log2blksz) {
- printf(" ** %s read error - block\n", __func__);
- return 0;
- }
- block_len = byte_len & ~(ext4fs_block_dev_desc->blksz - 1);
- buf += block_len;
- byte_len -= block_len;
- sector += block_len / ext4fs_block_dev_desc->blksz;
-
- if (byte_len != 0) {
- /* read rest of data which are not in whole sector */
- if (ext4fs_block_dev_desc->
- block_read(ext4fs_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;