1 /*
2 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.util.zip;
27
28 import java.io.FilterInputStream;
29 import java.io.InputStream;
30 import java.io.IOException;
31 import java.io.EOFException;
32
33 /**
34 * This class implements a stream filter for uncompressing data in the
35 * "deflate" compression format. It is also used as the basis for other
36 * decompression filters, such as GZIPInputStream.
37 *
38 * @see Inflater
39 * @author David Connelly
40 */
41 public
42 class InflaterInputStream extends FilterInputStream {
43 /**
44 * Decompressor for this stream.
45 */
46 protected Inflater inf;
47
48 /**
49 * Input buffer for decompression.
50 */
51 protected byte[] buf;
52
53 /**
54 * Original input buffer.
55 */
56 protected byte[] originBuf;
57
58 /**
59 * Length of input buffer.
60 */
61 protected int len;
62
63 private boolean closed = false;
64 // this flag is set to true after EOF has reached
65 private boolean reachEOF = false;
66
67 private ZipCryption zipCryption;
68
69 /**
70 * Check to make sure that this stream has not been closed
71 */
72 private void ensureOpen() throws IOException {
73 if (closed) {
74 throw new IOException("Stream closed");
75 }
76 }
77
78
79 /**
80 * Creates a new input stream with the specified decompressor and
81 * buffer size.
82 * @param in the input stream
83 * @param inf the decompressor ("inflater")
84 * @param size the input buffer size
85 * @exception IllegalArgumentException if {@code size <= 0}
86 */
87 public InflaterInputStream(InputStream in, Inflater inf, int size) {
88 super(in);
89 if (in == null || inf == null) {
90 throw new NullPointerException();
91 } else if (size <= 0) {
92 throw new IllegalArgumentException("buffer size <= 0");
93 }
94 this.inf = inf;
95 buf = new byte[size];
96 originBuf = new byte[size];
97 }
98
99 /**
100 * Creates a new input stream with the specified decompressor and a
101 * default buffer size.
102 * @param in the input stream
103 * @param inf the decompressor ("inflater")
104 */
105 public InflaterInputStream(InputStream in, Inflater inf) {
106 this(in, inf, 512);
107 }
108
109 boolean usesDefaultInflater = false;
110
111 /**
112 * Creates a new input stream with a default decompressor and buffer size.
113 * @param in the input stream
114 */
115 public InflaterInputStream(InputStream in) {
116 this(in, new Inflater());
117 usesDefaultInflater = true;
118 }
119
120 private byte[] singleByteBuf = new byte[1];
121
122 /**
123 * Reads a byte of uncompressed data. This method will block until
124 * enough input is available for decompression.
125 * @return the byte read, or -1 if end of compressed input is reached
126 * @exception IOException if an I/O error has occurred
127 */
128 public int read() throws IOException {
129 ensureOpen();
130 return read(singleByteBuf, 0, 1) == -1 ? -1 : Byte.toUnsignedInt(singleByteBuf[0]);
131 }
132
133 /**
134 * Reads uncompressed data into an array of bytes. If <code>len</code> is not
135 * zero, the method will block until some input can be decompressed; otherwise,
136 * no bytes are read and <code>0</code> is returned.
137 * @param b the buffer into which the data is read
138 * @param off the start offset in the destination array <code>b</code>
139 * @param len the maximum number of bytes read
140 * @return the actual number of bytes read, or -1 if the end of the
141 * compressed input is reached or a preset dictionary is needed
142 * @exception NullPointerException If <code>b</code> is <code>null</code>.
143 * @exception IndexOutOfBoundsException If <code>off</code> is negative,
144 * <code>len</code> is negative, or <code>len</code> is greater than
145 * <code>b.length - off</code>
146 * @exception ZipException if a ZIP format error has occurred
147 * @exception IOException if an I/O error has occurred
148 */
149 public int read(byte[] b, int off, int len) throws IOException {
150 ensureOpen();
151 if (b == null) {
152 throw new NullPointerException();
153 } else if (off < 0 || len < 0 || len > b.length - off) {
154 throw new IndexOutOfBoundsException();
155 } else if (len == 0) {
156 return 0;
157 }
158 try {
159 int n;
160 while ((n = inf.inflate(b, off, len)) == 0) {
161 if (inf.finished() || inf.needsDictionary()) {
162 reachEOF = true;
163 return -1;
164 }
165 if (inf.needsInput()) {
166 fill();
167 }
168 }
169 return n;
170 } catch (DataFormatException e) {
171 String s = e.getMessage();
172 throw new ZipException(s != null ? s : "Invalid ZLIB data format");
173 }
174 }
175
176 /**
177 * Returns 0 after EOF has been reached, otherwise always return 1.
178 * <p>
179 * Programs should not count on this method to return the actual number
180 * of bytes that could be read without blocking.
181 *
182 * @return 1 before EOF and 0 after EOF.
183 * @exception IOException if an I/O error occurs.
184 *
185 */
186 public int available() throws IOException {
187 ensureOpen();
188 if (reachEOF) {
189 return 0;
190 } else {
191 return 1;
192 }
193 }
194
195 private byte[] b = new byte[512];
196
197 /**
198 * Skips specified number of bytes of uncompressed data.
199 * @param n the number of bytes to skip
200 * @return the actual number of bytes skipped.
201 * @exception IOException if an I/O error has occurred
202 * @exception IllegalArgumentException if {@code n < 0}
203 */
204 public long skip(long n) throws IOException {
205 if (n < 0) {
206 throw new IllegalArgumentException("negative skip length");
207 }
208 ensureOpen();
209 int max = (int)Math.min(n, Integer.MAX_VALUE);
210 int total = 0;
211 while (total < max) {
212 int len = max - total;
213 if (len > b.length) {
214 len = b.length;
215 }
216 len = read(b, 0, len);
217 if (len == -1) {
218 reachEOF = true;
219 break;
220 }
221 total += len;
222 }
223 return total;
224 }
225
226 /**
227 * Closes this input stream and releases any system resources associated
228 * with the stream.
229 * @exception IOException if an I/O error has occurred
230 */
231 public void close() throws IOException {
232 if (!closed) {
233 if (usesDefaultInflater)
234 inf.end();
235 in.close();
236 closed = true;
237 }
238 }
239
240 /**
241 * Fills input buffer with more data to decompress.
242 * @exception IOException if an I/O error has occurred
243 */
244 protected void fill() throws IOException {
245 ensureOpen();
246 len = in.read(buf, 0, buf.length);
247 if (len == -1) {
248 throw new EOFException("Unexpected end of ZLIB input stream");
249 }
250
251 if (zipCryption != null) {
252 System.arraycopy(buf, 0, originBuf, 0, len);
253 zipCryption.decryptBytes(buf, 0, len);
254 }
255
256 inf.setInput(buf, 0, len);
257 }
258
259 /**
260 * Tests if this input stream supports the <code>mark</code> and
261 * <code>reset</code> methods. The <code>markSupported</code>
262 * method of <code>InflaterInputStream</code> returns
263 * <code>false</code>.
264 *
265 * @return a <code>boolean</code> indicating if this stream type supports
266 * the <code>mark</code> and <code>reset</code> methods.
267 * @see java.io.InputStream#mark(int)
268 * @see java.io.InputStream#reset()
269 */
270 public boolean markSupported() {
271 return false;
272 }
273
274 /**
275 * Marks the current position in this input stream.
276 *
277 * <p> The <code>mark</code> method of <code>InflaterInputStream</code>
278 * does nothing.
279 *
280 * @param readlimit the maximum limit of bytes that can be read before
281 * the mark position becomes invalid.
282 * @see java.io.InputStream#reset()
283 */
284 public synchronized void mark(int readlimit) {
285 }
286
287 /**
288 * Repositions this stream to the position at the time the
289 * <code>mark</code> method was last called on this input stream.
290 *
291 * <p> The method <code>reset</code> for class
292 * <code>InflaterInputStream</code> does nothing except throw an
293 * <code>IOException</code>.
294 *
295 * @exception IOException if this method is invoked.
296 * @see java.io.InputStream#mark(int)
297 * @see java.io.IOException
298 */
299 public synchronized void reset() throws IOException {
300 throw new IOException("mark/reset not supported");
301 }
302
303 /**
304 * Set ZIP encryption/decryption engine to this inflater.
305 * @param zipCryption ZIP encrypt/decrypt engine.
306 */
307 public void setZipCryption(ZipCryption zipCryption) {
308 this.zipCryption = zipCryption;
309 }
310 }