poifsfilesystem.java

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/* ====================================================================
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
==================================================================== */
        

package org.apache.poi.poifs.filesystem;

import java.io.ByteArrayInputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PushbackInputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import org.apache.poi.poifs.common.POIFSConstants;
import org.apache.poi.poifs.dev.POIFSViewable;
import org.apache.poi.poifs.property.DirectoryProperty;
import org.apache.poi.poifs.property.Property;
import org.apache.poi.poifs.property.PropertyTable;
import org.apache.poi.poifs.storage.BATBlock;
import org.apache.poi.poifs.storage.BlockAllocationTableReader;
import org.apache.poi.poifs.storage.BlockAllocationTableWriter;
import org.apache.poi.poifs.storage.BlockList;
import org.apache.poi.poifs.storage.BlockWritable;
import org.apache.poi.poifs.storage.HeaderBlockConstants;
import org.apache.poi.poifs.storage.HeaderBlockReader;
import org.apache.poi.poifs.storage.HeaderBlockWriter;
import org.apache.poi.poifs.storage.RawDataBlockList;
import org.apache.poi.poifs.storage.SmallBlockTableReader;
import org.apache.poi.poifs.storage.SmallBlockTableWriter;
import org.apache.poi.util.IOUtils;
import org.apache.poi.util.LongField;
import org.apache.poi.util.POILogFactory;
import org.apache.poi.util.POILogger;

/**
 * This is the main class of the POIFS system; it manages the entire
 * life cycle of the filesystem.
 *
 * @author Marc Johnson (mjohnson at apache dot org)
 */

public class POIFSFileSystem
    implements POIFSViewable
{
	private static final POILogger _logger =
		POILogFactory.getLogger(POIFSFileSystem.class);
    
    private static final class CloseIgnoringInputStream extends InputStream {

        private final InputStream _is;
        public CloseIgnoringInputStream(InputStream is) {
            _is = is;
        }
        public int read() throws IOException {
            return _is.read();
        }
        public int read(byte[] b, int off, int len) throws IOException {
            return _is.read(b, off, len);
        }
        public void close() {
            // do nothing
        }
    }
    
    /**
     * Convenience method for clients that want to avoid the auto-close behaviour of the constructor.
     */
    public static InputStream createNonClosingInputStream(InputStream is) {
        return new CloseIgnoringInputStream(is);
    }
    
    private PropertyTable _property_table;
    private List          _documents;
    private DirectoryNode _root;
    
    /**
     * What big block size the file uses. Most files
     *  use 512 bytes, but a few use 4096
     */
    private int bigBlockSize = POIFSConstants.BIG_BLOCK_SIZE;

    /**
     * Constructor, intended for writing
     */
    public POIFSFileSystem()
    {
        _property_table = new PropertyTable();
        _documents      = new ArrayList();
        _root           = null;
    }

    /**
     * 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 POIFSFileSystem(InputStream stream)
        throws IOException
    {
        this();
        boolean success = false;

        HeaderBlockReader header_block_reader;
        RawDataBlockList data_blocks;
        try {
            // read the header block from the stream
            header_block_reader = new HeaderBlockReader(stream);
            bigBlockSize = header_block_reader.getBigBlockSize();
            
            // read the rest of the stream into blocks
            data_blocks = new RawDataBlockList(stream, bigBlockSize);
            success = true;
        } finally {
            closeInputStream(stream, success);
        }
        

        // set up the block allocation table (necessary for the
        // data_blocks to be manageable
        new BlockAllocationTableReader(header_block_reader.getBATCount(),
                                       header_block_reader.getBATArray(),
                                       header_block_reader.getXBATCount(),
                                       header_block_reader.getXBATIndex(),
                                       data_blocks);

        // get property table from the document
        PropertyTable properties =
            new PropertyTable(header_block_reader.getPropertyStart(),
                              data_blocks);

        // init documents
        processProperties(SmallBlockTableReader
            .getSmallDocumentBlocks(data_blocks, properties
                .getRoot(), header_block_reader
                    .getSBATStart()), data_blocks, properties.getRoot()
                        .getChildren(), null);
    }
    /**
     * @param stream the stream to be closed
     * @param success <code>false</code> if an exception is currently being thrown in the calling method
     */
    private void closeInputStream(InputStream stream, boolean success) {
        
        if(stream.markSupported() && !(stream instanceof ByteArrayInputStream)) {
            String msg = "POIFS is closing the supplied input stream of type (" 
                    + stream.getClass().getName() + ") which supports mark/reset.  "
                    + "This will be a problem for the caller if the stream will still be used.  "
                    + "If that is the case the caller should wrap the input stream to avoid this close logic.  "
                    + "This warning is only temporary and will not be present in future versions of POI.";
            _logger.log(POILogger.WARN, msg);
        }
        try {
            stream.close();
        } catch (IOException e) {
            if(success) {
                throw new RuntimeException(e);
            }
            // else not success? Try block did not complete normally 
            // just print stack trace and leave original ex to be thrown
            e.printStackTrace();
        }
    }

    /**
     * Checks that the supplied InputStream (which MUST
     *  support mark and reset, or be a PushbackInputStream) 
     *  has a POIFS (OLE2) header at the start of it.
     * If your InputStream does not support mark / reset,
     *  then wrap it in a PushBackInputStream, then be
     *  sure to always use that, and not the original!
     * @param inp An InputStream which supports either mark/reset, or is a PushbackInputStream 
     */
    public static boolean hasPOIFSHeader(InputStream inp) throws IOException {
        // We want to peek at the first 8 bytes 
        inp.mark(8);

        byte[] header = new byte[8];
        IOUtils.readFully(inp, header);
        LongField signature = new LongField(HeaderBlockConstants._signature_offset, header);

        // Wind back those 8 bytes
        if(inp instanceof PushbackInputStream) {
            PushbackInputStream pin = (PushbackInputStream)inp;
            pin.unread(header);
        } else {
            inp.reset();
        }
        
        // Did it match the signature?
        return (signature.get() == HeaderBlockConstants._signature);
    }

    /**
     * Create a new document to be added to the root directory
     *
     * @param stream the InputStream from which the document's data
     *               will be obtained
     * @param name the name of the new POIFSDocument
     *
     * @return the new DocumentEntry
     *
     * @exception IOException on error creating the new POIFSDocument
     */

    public DocumentEntry createDocument(final InputStream stream,
                                        final String name)
        throws IOException
    {
        return getRoot().createDocument(name, stream);
    }

    /**
     * create a new DocumentEntry in the root entry; the data will be
     * provided later
     *
     * @param name the name of the new DocumentEntry
     * @param size the size of the new DocumentEntry
     * @param writer the writer of the new DocumentEntry
     *
     * @return the new DocumentEntry
     *
     * @exception IOException
     */

    public DocumentEntry createDocument(final String name, final int size,
                                        final POIFSWriterListener writer)
        throws IOException
    {
        return getRoot().createDocument(name, size, writer);
    }

    /**
     * create a new DirectoryEntry in the root directory
     *
     * @param name the name of the new DirectoryEntry
     *
     * @return the new DirectoryEntry
     *
     * @exception IOException on name duplication
     */

    public DirectoryEntry createDirectory(final String name)
        throws IOException
    {
        return getRoot().createDirectory(name);
    }
    
    /**
     * Write the filesystem out
     *
     * @param stream the OutputStream to which the filesystem will be
     *               written
     *
     * @exception IOException thrown on errors writing to the stream
     */

    public void writeFilesystem(final OutputStream stream)
        throws IOException
    {

        // get the property table ready
        _property_table.preWrite();

        // create the small block store, and the SBAT