/**
* Load the block, extending the underlying stream if needed
*/
public override ByteBuffer CreateBlockIfNeeded(int offset)
{
bool firstInStore = false;
// If we are the first block to be allocated, initialise the stream
if (_mini_stream.GetStartBlock() == POIFSConstants.END_OF_CHAIN)
{
firstInStore = true;
}
// Try to Get it without extending the stream
if (!firstInStore)
{
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);
// If we are the first block to be allocated, initialise the stream
if (firstInStore)
{
_filesystem.PropertyTable.Root.StartBlock = (newBigBlock);
_mini_stream = new NPOIFSStream(_filesystem, newBigBlock);
}
else
{
// 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 the real small block
return(CreateBlockIfNeeded(offset));
}
/**
* 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));
}
}
