private void readBAT(int batAt, ChainLoopDetector loopDetector) throws IOException {
loopDetector.claim(batAt);
ByteBuffer fatData = getBlockAt(batAt);
BATBlock bat = BATBlock.createBATBlock(bigBlockSize, fatData);
bat.setOurBlockIndex(batAt);
_bat_blocks.add(bat);
}
private BATBlock createBAT(int offset, boolean isBAT) throws IOException {
// Create a new BATBlock
BATBlock newBAT = BATBlock.createEmptyBATBlock(bigBlockSize, !isBAT);
newBAT.setOurBlockIndex(offset);
// Ensure there's a spot in the file for it
ByteBuffer buffer = ByteBuffer.allocate(bigBlockSize.getBigBlockSize());
int writeTo = (1 + offset) * bigBlockSize.getBigBlockSize(); // Header isn't in BATs
_data.write(buffer, writeTo);
// All done
return newBAT;
}
/** Has our in-memory objects write their state to their backing blocks */
private void syncWithDataSource() throws IOException {
// HeaderBlock
HeaderBlockWriter hbw = new HeaderBlockWriter(_header);
hbw.writeBlock(getBlockAt(-1));
// BATs
for (BATBlock bat : _bat_blocks) {
ByteBuffer block = getBlockAt(bat.getOurBlockIndex());
BlockAllocationTableWriter.writeBlock(bat, block);
}
// SBATs
_mini_store.syncWithDataSource();
// Properties
_property_table.write(new NPOIFSStream(this, _header.getPropertyStart()));
}
/**
* Read and process the PropertiesTable and the FAT / XFAT blocks, so that we're ready to work
* with the file
*/
private void readCoreContents() throws IOException {
// Grab the block size
bigBlockSize = _header.getBigBlockSize();
// 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
for (int fatAt : _header.getBATArray()) {
readBAT(fatAt, loopDetector);
}
// Work out how many FAT blocks remain in the XFATs
int remainingFATs = _header.getBATCount() - _header.getBATArray().length;
// Now read the XFAT blocks, and the FATs within them
BATBlock xfat;
int nextAt = _header.getXBATIndex();
for (int i = 0; i < _header.getXBATCount(); i++) {
loopDetector.claim(nextAt);
ByteBuffer fatData = getBlockAt(nextAt);
xfat = BATBlock.createBATBlock(bigBlockSize, fatData);
xfat.setOurBlockIndex(nextAt);
nextAt = xfat.getValueAt(bigBlockSize.getXBATEntriesPerBlock());
_xbat_blocks.add(xfat);
// Process all the (used) FATs from this XFAT
int xbatFATs = Math.min(remainingFATs, bigBlockSize.getXBATEntriesPerBlock());
for (int j = 0; j < xbatFATs; j++) {
int fatAt = xfat.getValueAt(j);
if (fatAt == POIFSConstants.UNUSED_BLOCK || fatAt == POIFSConstants.END_OF_CHAIN) break;
readBAT(fatAt, loopDetector);
}
remainingFATs -= xbatFATs;
}
// 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 ArrayList<BATBlock>();
_mini_store = new NPOIFSMiniStore(this, _property_table.getRoot(), sbats, _header);
nextAt = _header.getSBATStart();
for (int i = 0; i < _header.getSBATCount(); i++) {
loopDetector.claim(nextAt);
ByteBuffer fatData = getBlockAt(nextAt);
sfat = BATBlock.createBATBlock(bigBlockSize, fatData);
sfat.setOurBlockIndex(nextAt);
sbats.add(sfat);
nextAt = getNextBlock(nextAt);
}
}
/** Constructor, intended for writing */
public NPOIFSFileSystem() {
this(true);
// Mark us as having a single empty BAT at offset 0
_header.setBATCount(1);
_header.setBATArray(new int[] {0});
_bat_blocks.add(BATBlock.createEmptyBATBlock(bigBlockSize, false));
setNextBlock(0, POIFSConstants.FAT_SECTOR_BLOCK);
// Now associate the properties with the empty block
_property_table.setStartBlock(1);
setNextBlock(1, POIFSConstants.END_OF_CHAIN);
}
/**
* Create a POIFSFileSystem from an <tt>InputStream</tt>. Normally the stream is read until EOF.
* The stream is always closed.
*
* <p>Some streams are usable after reaching EOF (typically those that return <code>true</code>
* for <tt>markSupported()</tt>). In the unlikely case that the caller has such a stream
* <i>and</i> needs to use it after this constructor completes, a work around is to wrap the
* stream in order to trap the <tt>close()</tt> call. A convenience method (
* <tt>createNonClosingInputStream()</tt>) has been provided for this purpose:
*
* <pre>
* InputStream wrappedStream = POIFSFileSystem.createNonClosingInputStream(is);
* HSSFWorkbook wb = new HSSFWorkbook(wrappedStream);
* is.reset();
* doSomethingElse(is);
* </pre>
*
* Note also the special case of <tt>ByteArrayInputStream</tt> for which the <tt>close()</tt>
* method does nothing.
*
* <pre>
* ByteArrayInputStream bais = ...
* HSSFWorkbook wb = new HSSFWorkbook(bais); // calls bais.close() !
* bais.reset(); // no problem
* doSomethingElse(bais);
* </pre>
*
* @param stream the InputStream from which to read the data
* @exception IOException on errors reading, or on invalid data
*/
public NPOIFSFileSystem(InputStream stream) throws IOException {
this(false);
ReadableByteChannel channel = null;
boolean success = false;
try {
// Turn our InputStream into something NIO based
channel = Channels.newChannel(stream);
// Get the header
ByteBuffer headerBuffer = ByteBuffer.allocate(POIFSConstants.SMALLER_BIG_BLOCK_SIZE);
IOUtils.readFully(channel, headerBuffer);
// Have the header processed
_header = new HeaderBlock(headerBuffer);
// Sanity check the block count
BlockAllocationTableReader.sanityCheckBlockCount(_header.getBATCount());
// We need to buffer the whole file into memory when
// working with an InputStream.
// The max possible size is when each BAT block entry is used
int maxSize = BATBlock.calculateMaximumSize(_header);
ByteBuffer data = ByteBuffer.allocate(maxSize);
// Copy in the header
headerBuffer.position(0);
data.put(headerBuffer);
data.position(headerBuffer.capacity());
// Now read the rest of the stream
IOUtils.readFully(channel, data);
success = true;
// Turn it into a DataSource
_data = new ByteArrayBackedDataSource(data.array(), data.position());
} finally {
// As per the constructor contract, always close the stream
if (channel != null) channel.close();
closeInputStream(stream, success);
}
// Now process the various entries
readCoreContents();
}
/**
* 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.
*/
@Override
protected int getFreeBlock() throws IOException {
// First up, do we have any spare ones?
int offset = 0;
for (int i = 0; i < _bat_blocks.size(); i++) {
int numSectors = bigBlockSize.getBATEntriesPerBlock();
// Check this one
BATBlock bat = _bat_blocks.get(i);
if (bat.hasFreeSectors()) {
// Claim one of them and return it
for (int j = 0; j < numSectors; j++) {
int batValue = bat.getValueAt(j);
if (batValue == POIFSConstants.UNUSED_BLOCK) {
// Bingo
return offset + j;
}
}
}
// Move onto the next BAT
offset += numSectors;
}
// If we get here, then there aren't any free sectors
// in any of the BATs, so we need another BAT
BATBlock bat = createBAT(offset, true);
bat.setValueAt(0, POIFSConstants.FAT_SECTOR_BLOCK);
_bat_blocks.add(bat);
// Now store a reference to the BAT in the required place
if (_header.getBATCount() >= 109) {
// Needs to come from an XBAT
BATBlock xbat = null;
for (BATBlock x : _xbat_blocks) {
if (x.hasFreeSectors()) {
xbat = x;
break;
}
}
if (xbat == null) {
// Oh joy, we need a new XBAT too...
xbat = createBAT(offset + 1, false);
xbat.setValueAt(0, offset);
bat.setValueAt(1, POIFSConstants.DIFAT_SECTOR_BLOCK);
// Will go one place higher as XBAT added in
offset++;
// Chain it
if (_xbat_blocks.size() == 0) {
_header.setXBATStart(offset);
} else {
_xbat_blocks
.get(_xbat_blocks.size() - 1)
.setValueAt(bigBlockSize.getXBATEntriesPerBlock(), offset);
}
_xbat_blocks.add(xbat);
_header.setXBATCount(_xbat_blocks.size());
}
// Allocate us in the XBAT
for (int i = 0; i < bigBlockSize.getXBATEntriesPerBlock(); i++) {
if (xbat.getValueAt(i) == POIFSConstants.UNUSED_BLOCK) {
xbat.setValueAt(i, offset);
}
}
} else {
// Store us in the header
int[] newBATs = new int[_header.getBATCount() + 1];
System.arraycopy(_header.getBATArray(), 0, newBATs, 0, newBATs.length - 1);
newBATs[newBATs.length - 1] = offset;
_header.setBATArray(newBATs);
}
_header.setBATCount(_bat_blocks.size());
// The current offset stores us, but the next one is free
return offset + 1;
}
/** Returns the BATBlock that handles the specified offset, and the relative index within it */
@Override
protected BATBlockAndIndex getBATBlockAndIndex(final int offset) {
return BATBlock.getBATBlockAndIndex(offset, _header, _bat_blocks);
}
