| |
| /* ==================================================================== |
| 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.storage; |
| |
| import java.io.*; |
| |
| import org.apache.poi.poifs.common.POIFSConstants; |
| import org.apache.poi.poifs.filesystem.OfficeXmlFileException; |
| import org.apache.poi.util.IOUtils; |
| import org.apache.poi.util.IntegerField; |
| import org.apache.poi.util.LittleEndian; |
| import org.apache.poi.util.LittleEndianConsts; |
| import org.apache.poi.util.LongField; |
| |
| /** |
| * The block containing the archive header |
| * |
| * @author Marc Johnson (mjohnson at apache dot org) |
| */ |
| |
| public class HeaderBlockReader |
| implements HeaderBlockConstants |
| { |
| /** |
| * What big block size the file uses. Most files |
| * use 512 bytes, but a few use 4096 |
| */ |
| private int bigBlockSize = POIFSConstants.BIG_BLOCK_SIZE; |
| |
| // number of big block allocation table blocks (int) |
| private IntegerField _bat_count; |
| |
| // start of the property set block (int index of the property set |
| // chain's first big block) |
| private IntegerField _property_start; |
| |
| // start of the small block allocation table (int index of small |
| // block allocation table's first big block) |
| private IntegerField _sbat_start; |
| |
| // big block index for extension to the big block allocation table |
| private IntegerField _xbat_start; |
| private IntegerField _xbat_count; |
| private byte[] _data; |
| |
| /** |
| * create a new HeaderBlockReader from an InputStream |
| * |
| * @param stream the source InputStream |
| * |
| * @exception IOException on errors or bad data |
| */ |
| |
| public HeaderBlockReader(final InputStream stream) |
| throws IOException |
| { |
| // At this point, we don't know how big our |
| // block sizes are |
| // So, read the first 32 bytes to check, then |
| // read the rest of the block |
| byte[] blockStart = new byte[32]; |
| int bsCount = IOUtils.readFully(stream, blockStart); |
| if(bsCount != 32) { |
| alertShortRead(bsCount); |
| } |
| |
| // Figure out our block size |
| if(blockStart[30] == 12) { |
| bigBlockSize = POIFSConstants.LARGER_BIG_BLOCK_SIZE; |
| } |
| _data = new byte[ bigBlockSize ]; |
| System.arraycopy(blockStart, 0, _data, 0, blockStart.length); |
| |
| // Now we can read the rest of our header |
| int byte_count = IOUtils.readFully(stream, _data, blockStart.length, _data.length - blockStart.length); |
| if (byte_count+bsCount != bigBlockSize) { |
| alertShortRead(byte_count); |
| } |
| |
| // verify signature |
| LongField signature = new LongField(_signature_offset, _data); |
| |
| if (signature.get() != _signature) |
| { |
| // Is it one of the usual suspects? |
| byte[] OOXML_FILE_HEADER = POIFSConstants.OOXML_FILE_HEADER; |
| if(_data[0] == OOXML_FILE_HEADER[0] && |
| _data[1] == OOXML_FILE_HEADER[1] && |
| _data[2] == OOXML_FILE_HEADER[2] && |
| _data[3] == OOXML_FILE_HEADER[3]) { |
| throw new OfficeXmlFileException("The supplied data appears to be in the Office 2007+ XML. POI only supports OLE2 Office documents"); |
| } |
| |
| // Give a generic error |
| throw new IOException("Invalid header signature; read " |
| + signature.get() + ", expected " |
| + _signature); |
| } |
| _bat_count = new IntegerField(_bat_count_offset, _data); |
| _property_start = new IntegerField(_property_start_offset, _data); |
| _sbat_start = new IntegerField(_sbat_start_offset, _data); |
| _xbat_start = new IntegerField(_xbat_start_offset, _data); |
| _xbat_count = new IntegerField(_xbat_count_offset, _data); |
| } |
| |
| private void alertShortRead(int read) throws IOException { |
| if (read == -1) |
| //Cant have -1 bytes read in the error message! |
| read = 0; |
| String type = " byte" + ((read == 1) ? ("") |
| : ("s")); |
| |
| throw new IOException("Unable to read entire header; " |
| + read + type + " read; expected " |
| + bigBlockSize + " bytes"); |
| } |
| |
| /** |
| * get start of Property Table |
| * |
| * @return the index of the first block of the Property Table |
| */ |
| public int getPropertyStart() |
| { |
| return _property_start.get(); |
| } |
| |
| /** |
| * @return start of small block allocation table |
| */ |
| |
| public int getSBATStart() |
| { |
| return _sbat_start.get(); |
| } |
| |
| /** |
| * @return number of BAT blocks |
| */ |
| |
| public int getBATCount() |
| { |
| return _bat_count.get(); |
| } |
| |
| /** |
| * @return BAT array |
| */ |
| |
| public int [] getBATArray() |
| { |
| int[] result = new int[ _max_bats_in_header ]; |
| int offset = _bat_array_offset; |
| |
| for (int j = 0; j < _max_bats_in_header; j++) |
| { |
| result[ j ] = LittleEndian.getInt(_data, offset); |
| offset += LittleEndianConsts.INT_SIZE; |
| } |
| return result; |
| } |
| |
| /** |
| * @return XBAT count |
| */ |
| |
| public int getXBATCount() |
| { |
| return _xbat_count.get(); |
| } |
| |
| /** |
| * @return XBAT index |
| */ |
| |
| public int getXBATIndex() |
| { |
| return _xbat_start.get(); |
| } |
| |
| /** |
| * @return The Big Block size, normally 512 bytes, sometimes 4096 bytes |
| */ |
| public int getBigBlockSize() { |
| return bigBlockSize; |
| } |
| } // end public class HeaderBlockReader |
| |