/**
* Read and process the PropertiesTable and the
* FAT / XFAT blocks, so that we're Ready to
* work with the file
*/
private void ReadCoreContents()
{
// Grab the block size
bigBlockSize = _header.BigBlockSize;
// Each block should only ever be used by one of the
// FAT, XFAT or Property Table. Ensure it does
ChainLoopDetector loopDetector = GetChainLoopDetector();
// Read the FAT blocks
foreach (int fatAt in _header.BATArray)
{
ReadBAT(fatAt, loopDetector);
}
// Now read the XFAT blocks, and the FATs within them
BATBlock xfat;
int nextAt = _header.XBATIndex;
for (int i = 0; i < _header.XBATCount; i++)
{
loopDetector.Claim(nextAt);
ByteBuffer fatData = GetBlockAt(nextAt);
xfat = BATBlock.CreateBATBlock(bigBlockSize, fatData);
xfat.OurBlockIndex = nextAt;
nextAt = xfat.GetValueAt(bigBlockSize.GetXBATEntriesPerBlock());
_xbat_blocks.Add(xfat);
for (int j = 0; j < bigBlockSize.GetXBATEntriesPerBlock(); j++)
{
int fatAt = xfat.GetValueAt(j);
if (fatAt == POIFSConstants.UNUSED_BLOCK)
{
break;
}
ReadBAT(fatAt, loopDetector);
}
}
// We're now able to load steams
// Use this to read in the properties
_property_table = new NPropertyTable(_header, this);
// Finally read the Small Stream FAT (SBAT) blocks
BATBlock sfat;
List <BATBlock> sbats = new List <BATBlock>();
_mini_store = new NPOIFSMiniStore(this, _property_table.Root, sbats, _header);
nextAt = _header.SBATStart;
for (int i = 0; i < _header.SBATCount; i++)
{
loopDetector.Claim(nextAt);
ByteBuffer fatData = GetBlockAt(nextAt);
sfat = BATBlock.CreateBATBlock(bigBlockSize, fatData);
sfat.OurBlockIndex = nextAt;
sbats.Add(sfat);
nextAt = GetNextBlock(nextAt);
}
}
private void ReadBAT(int batAt, ChainLoopDetector loopDetector)
{
loopDetector.Claim(batAt);
ByteBuffer fatData = GetBlockAt(batAt);
// byte[] fatData = GetBlockAt(batAt);
BATBlock bat = BATBlock.CreateBATBlock(bigBlockSize, fatData);
bat.OurBlockIndex = batAt;
_bat_blocks.Add(bat);
}
private void free(ChainLoopDetector loopDetector)
{
int nextBlock = startBlock;
while (nextBlock != POIFSConstants.END_OF_CHAIN)
{
int thisBlock = nextBlock;
loopDetector.Claim(thisBlock);
nextBlock = blockStore.GetNextBlock(thisBlock);
blockStore.SetNextBlock(thisBlock, POIFSConstants.UNUSED_BLOCK);
}
this.startBlock = POIFSConstants.END_OF_CHAIN;
}
public StreamBlockByteBufferIterator(BlockStore blockStore, int firstBlock)
{
this.blockStore = blockStore;
this.nextBlock = firstBlock;
try
{
this.loopDetector = blockStore.GetChainLoopDetector();
}
catch (IOException e)
{
//throw new System.RuntimeException(e);
throw new Exception(e.Message);
}
}
/**
* Load the block, extending the underlying stream if needed
*/
public override ByteBuffer CreateBlockIfNeeded(int offset)
{
// Try to Get it without extending the stream
try
{
return(GetBlockAt(offset));
}
catch (IndexOutOfRangeException)
{
// Need to extend the stream
// TODO Replace this with proper append support
// For now, do the extending by hand...
// Ask for another block
int newBigBlock = _filesystem.GetFreeBlock();
_filesystem.CreateBlockIfNeeded(newBigBlock);
// Tack it onto the end of our chain
ChainLoopDetector loopDetector = _filesystem.GetChainLoopDetector();
int block = _mini_stream.GetStartBlock();
while (true)
{
loopDetector.Claim(block);
int next = _filesystem.GetNextBlock(block);
if (next == POIFSConstants.END_OF_CHAIN)
{
break;
}
block = next;
}
_filesystem.SetNextBlock(block, newBigBlock);
_filesystem.SetNextBlock(newBigBlock, POIFSConstants.END_OF_CHAIN);
// Now try again to Get it
return(CreateBlockIfNeeded(offset));
}
}
// TODO Streaming write support
// TODO then convert fixed sized write to use streaming internally
// TODO Append write support (probably streaming)
/**
* Frees all blocks in the stream
*/
public void free()
{
ChainLoopDetector loopDetector = blockStore.GetChainLoopDetector();
free(loopDetector);
}
/**
* Updates the contents of the stream to the new
* Set of bytes.
* Note - if this is property based, you'll still
* need to update the size in the property yourself
*/
public void UpdateContents(byte[] contents)
{
// How many blocks are we going to need?
int blockSize = blockStore.GetBlockStoreBlockSize();
int blocks = (int)Math.Ceiling(((double)contents.Length) / blockSize);
// Make sure we don't encounter a loop whilst overwriting
// the existing blocks
ChainLoopDetector loopDetector = blockStore.GetChainLoopDetector();
// Start writing
int prevBlock = POIFSConstants.END_OF_CHAIN;
int nextBlock = startBlock;
for (int i = 0; i < blocks; i++)
{
int thisBlock = nextBlock;
// Allocate a block if needed, otherwise figure
// out what the next block will be
if (thisBlock == POIFSConstants.END_OF_CHAIN)
{
thisBlock = blockStore.GetFreeBlock();
loopDetector.Claim(thisBlock);
// We're on the end of the chain
nextBlock = POIFSConstants.END_OF_CHAIN;
// Mark the previous block as carrying on to us if needed
if (prevBlock != POIFSConstants.END_OF_CHAIN)
{
blockStore.SetNextBlock(prevBlock, thisBlock);
}
blockStore.SetNextBlock(thisBlock, POIFSConstants.END_OF_CHAIN);
// If we've just written the first block on a
// new stream, save the start block offset
if (this.startBlock == POIFSConstants.END_OF_CHAIN)
{
this.startBlock = thisBlock;
}
}
else
{
loopDetector.Claim(thisBlock);
nextBlock = blockStore.GetNextBlock(thisBlock);
}
// Write it
//byte[] buffer = blockStore.CreateBlockIfNeeded(thisBlock);
ByteBuffer buffer = blockStore.CreateBlockIfNeeded(thisBlock);
int startAt = i * blockSize;
int endAt = Math.Min(contents.Length - startAt, blockSize);
buffer.Write(contents, startAt, endAt);
//for (int index = startAt, j = 0; index < endAt; index++, j++)
// buffer[j] = contents[index];
// Update pointers
prevBlock = thisBlock;
}
int lastBlock = prevBlock;
// If we're overwriting, free any remaining blocks
NPOIFSStream toFree = new NPOIFSStream(blockStore, nextBlock);
toFree.free(loopDetector);
// Mark the end of the stream
blockStore.SetNextBlock(lastBlock, POIFSConstants.END_OF_CHAIN);
}
/**
* Finds a free block, and returns its offset.
* This method will extend the file if needed, and if doing
* so, allocate new FAT blocks to Address the extra space.
*/
public override int GetFreeBlock()
{
int sectorsPerSBAT = _filesystem.GetBigBlockSizeDetails().GetBATEntriesPerBlock();
// First up, do we have any spare ones?
int offset = 0;
for (int i = 0; i < _sbat_blocks.Count; i++)
{
// Check this one
BATBlock sbat = _sbat_blocks[i];
if (sbat.HasFreeSectors)
{
// Claim one of them and return it
for (int j = 0; j < sectorsPerSBAT; j++)
{
int sbatValue = sbat.GetValueAt(j);
if (sbatValue == POIFSConstants.UNUSED_BLOCK)
{
// Bingo
return(offset + j);
}
}
}
// Move onto the next SBAT
offset += sectorsPerSBAT;
}
// If we Get here, then there aren't any
// free sectors in any of the SBATs
// So, we need to extend the chain and add another
// Create a new BATBlock
BATBlock newSBAT = BATBlock.CreateEmptyBATBlock(_filesystem.GetBigBlockSizeDetails(), false);
int batForSBAT = _filesystem.GetFreeBlock();
newSBAT.OurBlockIndex = batForSBAT;
// Are we the first SBAT?
if (_header.SBATCount == 0)
{
_header.SBATStart = batForSBAT;
_header.SBATBlockCount = 1;
}
else
{
// Find the end of the SBAT stream, and add the sbat in there
ChainLoopDetector loopDetector = _filesystem.GetChainLoopDetector();
int batOffset = _header.SBATStart;
while (true)
{
loopDetector.Claim(batOffset);
int nextBat = _filesystem.GetNextBlock(batOffset);
if (nextBat == POIFSConstants.END_OF_CHAIN)
{
break;
}
batOffset = nextBat;
}
// Add it in at the end
_filesystem.SetNextBlock(batOffset, batForSBAT);
// And update the count
_header.SBATBlockCount = _header.SBATCount + 1;
}
// Finish allocating
_filesystem.SetNextBlock(batForSBAT, POIFSConstants.END_OF_CHAIN);
_sbat_blocks.Add(newSBAT);
// Return our first spot
return(offset);
}
