/// <summary>
/// create a BlockAllocationTableReader for an existing filesystem. Side
/// effect: when this method finishes, the BAT blocks will have
/// been Removed from the raw block list, and any blocks labeled as
/// 'unused' in the block allocation table will also have been
/// Removed from the raw block list. </summary>
/// <param name="bigBlockSizse">the poifs bigBlockSize</param>
/// <param name="block_count">the number of BAT blocks making up the block allocation table</param>
/// <param name="block_array">the array of BAT block indices from the
/// filesystem's header</param>
/// <param name="xbat_count">the number of XBAT blocks</param>
/// <param name="xbat_index">the index of the first XBAT block</param>
/// <param name="raw_block_list">the list of RawDataBlocks</param>
public BlockAllocationTableReader(POIFSBigBlockSize bigBlockSizse,
int block_count,
int[] block_array,
int xbat_count,
int xbat_index,
BlockList raw_block_list)
: this(bigBlockSizse)
{
SanityCheckBlockCount(block_count);
RawDataBlock[] blocks = new RawDataBlock[block_count];
int limit = Math.Min(block_count, block_array.Length);
int block_index;
for (block_index = 0; block_index < limit; block_index++)
{
int nextOffset = block_array[block_index];
if (nextOffset > raw_block_list.BlockCount())
{
throw new IOException("Your file contains " + raw_block_list.BlockCount() +
" sectors, but the initial DIFAT array at index " + block_index +
" referenced block # " + nextOffset + ". This isn't allowed and " +
" your file is corrupt");
}
blocks[block_index] = (RawDataBlock)raw_block_list.Remove(nextOffset);
}
if (block_index < block_count)
{
// must have extended blocks
if (xbat_index < 0)
{
throw new IOException(
"BAT count exceeds limit, yet XBAT index indicates no valid entries");
}
int chain_index = xbat_index;
int max_entries_per_block = BATBlock.EntriesPerXBATBlock;
int chain_index_offset = BATBlock.XBATChainOffset;
// Each XBAT block contains either:
// (maximum number of sector indexes) + index of next XBAT
// some sector indexes + FREE sectors to max # + EndOfChain
for (int j = 0; j < xbat_count; j++)
{
limit = Math.Min(block_count - block_index,
max_entries_per_block);
byte[] data = raw_block_list.Remove(chain_index).Data;
int offset = 0;
for (int k = 0; k < limit; k++)
{
blocks[block_index++] =
(RawDataBlock)raw_block_list.Remove(LittleEndian.GetInt(data, offset));
offset += LittleEndianConsts.INT_SIZE;
}
chain_index = LittleEndian.GetInt(data, chain_index_offset);
if (chain_index == POIFSConstants.END_OF_CHAIN)
{
break;
}
}
}
if (block_index != block_count)
{
throw new IOException("Could not find all blocks");
}
// now that we have all of the raw data blocks, go through and
// create the indices
SetEntries((ListManagedBlock[])blocks, raw_block_list);
}
/// <summary>
/// create a BlockAllocationTableReader for an existing filesystem. Side
/// effect: when this method finishes, the BAT blocks will have
/// been Removed from the raw block list, and any blocks labeled as
/// 'unused' in the block allocation table will also have been
/// Removed from the raw block list. </summary>
/// <param name="bigBlockSizse">the poifs bigBlockSize</param>
/// <param name="block_count">the number of BAT blocks making up the block allocation table</param>
/// <param name="block_array">the array of BAT block indices from the
/// filesystem's header</param>
/// <param name="xbat_count">the number of XBAT blocks</param>
/// <param name="xbat_index">the index of the first XBAT block</param>
/// <param name="raw_block_list">the list of RawDataBlocks</param>
public BlockAllocationTableReader(POIFSBigBlockSize bigBlockSizse,
int block_count,
int[] block_array,
int xbat_count,
int xbat_index,
BlockList raw_block_list)
: this(bigBlockSizse)
{
SanityCheckBlockCount(block_count);
RawDataBlock[] blocks = new RawDataBlock[block_count];
int limit = Math.Min(block_count, block_array.Length);
int block_index;
for (block_index = 0; block_index < limit; block_index++)
{
int nextOffset = block_array[block_index];
if (nextOffset > raw_block_list.BlockCount())
{
throw new IOException("Your file contains " + raw_block_list.BlockCount() +
" sectors, but the initial DIFAT array at index " + block_index +
" referenced block # " + nextOffset + ". This isn't allowed and " +
" your file is corrupt");
}
blocks[block_index] = (RawDataBlock)raw_block_list.Remove(nextOffset);
}
if (block_index < block_count)
{
// must have extended blocks
if (xbat_index < 0)
{
throw new IOException(
"BAT count exceeds limit, yet XBAT index indicates no valid entries");
}
int chain_index = xbat_index;
int max_entries_per_block = BATBlock.EntriesPerXBATBlock;
int chain_index_offset = BATBlock.XBATChainOffset;
// Each XBAT block contains either:
// (maximum number of sector indexes) + index of next XBAT
// some sector indexes + FREE sectors to max # + EndOfChain
for (int j = 0; j < xbat_count; j++)
{
limit = Math.Min(block_count - block_index,
max_entries_per_block);
byte[] data = raw_block_list.Remove(chain_index).Data;
int offset = 0;
for (int k = 0; k < limit; k++)
{
blocks[block_index++] =
(RawDataBlock)raw_block_list.Remove(LittleEndian.GetInt(data, offset));
offset += LittleEndianConsts.INT_SIZE;
}
chain_index = LittleEndian.GetInt(data, chain_index_offset);
if (chain_index == POIFSConstants.END_OF_CHAIN)
{
break;
}
}
}
if (block_index != block_count)
{
throw new IOException("Could not find all blocks");
}
// now that we have all of the raw data blocks, go through and
// create the indices
SetEntries((ListManagedBlock[])blocks, raw_block_list);
}
