1
2 /* ====================================================================
3 Licensed to the Apache Software Foundation (ASF) under one or more
4 contributor license agreements. See the NOTICE file distributed with
5 this work for additional information regarding copyright ownership.
6 The ASF licenses this file to You under the Apache License, Version 2.0
7 (the "License"); you may not use this file except in compliance with
8 the License. You may obtain a copy of the License at
9
10 http://www.apache.org/licenses/LICENSE-2.0
11
12 Unless required by applicable law or agreed to in writing, software
13 distributed under the License is distributed on an "AS IS" BASIS,
14 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 See the License for the specific language governing permissions and
16 limitations under the License.
17 ==================================================================== */
18
19
20 package org.apache.poi.poifs.storage;
21
22 import java.io;
23
24 import org.apache.poi.poifs.common.POIFSConstants;
25 import org.apache.poi.poifs.filesystem.OfficeXmlFileException;
26 import org.apache.poi.util.IOUtils;
27 import org.apache.poi.util.IntegerField;
28 import org.apache.poi.util.LittleEndian;
29 import org.apache.poi.util.LittleEndianConsts;
30 import org.apache.poi.util.LongField;
31
32 /**
33 * The block containing the archive header
34 *
35 * @author Marc Johnson (mjohnson at apache dot org)
36 */
37
38 public class HeaderBlockReader
39 implements HeaderBlockConstants
40 {
41 /**
42 * What big block size the file uses. Most files
43 * use 512 bytes, but a few use 4096
44 */
45 private int bigBlockSize = POIFSConstants.BIG_BLOCK_SIZE;
46
47 // number of big block allocation table blocks (int)
48 private IntegerField _bat_count;
49
50 // start of the property set block (int index of the property set
51 // chain's first big block)
52 private IntegerField _property_start;
53
54 // start of the small block allocation table (int index of small
55 // block allocation table's first big block)
56 private IntegerField _sbat_start;
57
58 // big block index for extension to the big block allocation table
59 private IntegerField _xbat_start;
60 private IntegerField _xbat_count;
61 private byte[] _data;
62
63 /**
64 * create a new HeaderBlockReader from an InputStream
65 *
66 * @param stream the source InputStream
67 *
68 * @exception IOException on errors or bad data
69 */
70
71 public HeaderBlockReader(final InputStream stream)
72 throws IOException
73 {
74 // At this point, we don't know how big our
75 // block sizes are
76 // So, read the first 32 bytes to check, then
77 // read the rest of the block
78 byte[] blockStart = new byte[32];
79 int bsCount = IOUtils.readFully(stream, blockStart);
80 if(bsCount != 32) {
81 alertShortRead(bsCount);
82 }
83
84 // Figure out our block size
85 if(blockStart[30] == 12) {
86 bigBlockSize = POIFSConstants.LARGER_BIG_BLOCK_SIZE;
87 }
88 _data = new byte[ bigBlockSize ];
89 System.arraycopy(blockStart, 0, _data, 0, blockStart.length);
90
91 // Now we can read the rest of our header
92 int byte_count = IOUtils.readFully(stream, _data, blockStart.length, _data.length - blockStart.length);
93 if (byte_count+bsCount != bigBlockSize) {
94 alertShortRead(byte_count);
95 }
96
97 // verify signature
98 LongField signature = new LongField(_signature_offset, _data);
99
100 if (signature.get() != _signature)
101 {
102 // Is it one of the usual suspects?
103 byte[] OOXML_FILE_HEADER = POIFSConstants.OOXML_FILE_HEADER;
104 if(_data[0] == OOXML_FILE_HEADER[0] &&
105 _data[1] == OOXML_FILE_HEADER[1] &&
106 _data[2] == OOXML_FILE_HEADER[2] &&
107 _data[3] == OOXML_FILE_HEADER[3]) {
108 throw new OfficeXmlFileException("The supplied data appears to be in the Office 2007+ XML. POI only supports OLE2 Office documents");
109 }
110
111 // Give a generic error
112 throw new IOException("Invalid header signature; read "
113 + signature.get() + ", expected "
114 + _signature);
115 }
116 _bat_count = new IntegerField(_bat_count_offset, _data);
117 _property_start = new IntegerField(_property_start_offset, _data);
118 _sbat_start = new IntegerField(_sbat_start_offset, _data);
119 _xbat_start = new IntegerField(_xbat_start_offset, _data);
120 _xbat_count = new IntegerField(_xbat_count_offset, _data);
121 }
122
123 private void alertShortRead(int read) throws IOException {
124 if (read == -1)
125 //Cant have -1 bytes read in the error message!
126 read = 0;
127 String type = " byte" + ((read == 1) ? ("")
128 : ("s"));
129
130 throw new IOException("Unable to read entire header; "
131 + read + type + " read; expected "
132 + bigBlockSize + " bytes");
133 }
134
135 /**
136 * get start of Property Table
137 *
138 * @return the index of the first block of the Property Table
139 */
140 public int getPropertyStart()
141 {
142 return _property_start.get();
143 }
144
145 /**
146 * @return start of small block allocation table
147 */
148
149 public int getSBATStart()
150 {
151 return _sbat_start.get();
152 }
153
154 /**
155 * @return number of BAT blocks
156 */
157
158 public int getBATCount()
159 {
160 return _bat_count.get();
161 }
162
163 /**
164 * @return BAT array
165 */
166
167 public int [] getBATArray()
168 {
169 int[] result = new int[ _max_bats_in_header ];
170 int offset = _bat_array_offset;
171
172 for (int j = 0; j < _max_bats_in_header; j++)
173 {
174 result[ j ] = LittleEndian.getInt(_data, offset);
175 offset += LittleEndianConsts.INT_SIZE;
176 }
177 return result;
178 }
179
180 /**
181 * @return XBAT count
182 */
183
184 public int getXBATCount()
185 {
186 return _xbat_count.get();
187 }
188
189 /**
190 * @return XBAT index
191 */
192
193 public int getXBATIndex()
194 {
195 return _xbat_start.get();
196 }
197
198 /**
199 * @return The Big Block size, normally 512 bytes, sometimes 4096 bytes
200 */
201 public int getBigBlockSize() {
202 return bigBlockSize;
203 }
204 } // end public class HeaderBlockReader
205
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