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 * Length of input buffer.
55 */
56 protected int len;
57
58 private boolean closed = false;
59 // this flag is set to true after EOF has reached
60 private boolean reachEOF = false;
61
62 /**
63 * Check to make sure that this stream has not been closed
64 */
65 private void ensureOpen() throws IOException {
66 if (closed) {
67 throw new IOException("Stream closed");
68 }
69 }
70
71
72 /**
73 * Creates a new input stream with the specified decompressor and
74 * buffer size.
75 * @param in the input stream
76 * @param inf the decompressor ("inflater")
77 * @param size the input buffer size
78 * @exception IllegalArgumentException if {@code size <= 0}
79 */
80 public InflaterInputStream(InputStream in, Inflater inf, int size) {
81 super(in);
82 if (in == null || inf == null) {
83 throw new NullPointerException();
84 } else if (size <= 0) {
85 throw new IllegalArgumentException("buffer size <= 0");
86 }
87 this.inf = inf;
88 buf = new byte[size];
89 }
90
91 /**
92 * Creates a new input stream with the specified decompressor and a
93 * default buffer size.
94 * @param in the input stream
95 * @param inf the decompressor ("inflater")
96 */
97 public InflaterInputStream(InputStream in, Inflater inf) {
98 this(in, inf, 512);
99 }
100
101 boolean usesDefaultInflater = false;
102
103 /**
104 * Creates a new input stream with a default decompressor and buffer size.
105 * @param in the input stream
106 */
107 public InflaterInputStream(InputStream in) {
108 this(in, new Inflater());
109 usesDefaultInflater = true;
110 }
111
112 private byte[] singleByteBuf = new byte[1];
113
114 /**
115 * Reads a byte of uncompressed data. This method will block until
116 * enough input is available for decompression.
117 * @return the byte read, or -1 if end of compressed input is reached
118 * @exception IOException if an I/O error has occurred
119 */
120 public int read() throws IOException {
121 ensureOpen();
122 return read(singleByteBuf, 0, 1) == -1 ? -1 : Byte.toUnsignedInt(singleByteBuf[0]);
123 }
124
125 /**
126 * Reads uncompressed data into an array of bytes. If <code>len</code> is not
127 * zero, the method will block until some input can be decompressed; otherwise,
128 * no bytes are read and <code>0</code> is returned.
129 * @param b the buffer into which the data is read
130 * @param off the start offset in the destination array <code>b</code>
131 * @param len the maximum number of bytes read
132 * @return the actual number of bytes read, or -1 if the end of the
133 * compressed input is reached or a preset dictionary is needed
134 * @exception NullPointerException If <code>b</code> is <code>null</code>.
135 * @exception IndexOutOfBoundsException If <code>off</code> is negative,
136 * <code>len</code> is negative, or <code>len</code> is greater than
137 * <code>b.length - off</code>
138 * @exception ZipException if a ZIP format error has occurred
139 * @exception IOException if an I/O error has occurred
140 */
141 public int read(byte[] b, int off, int len) throws IOException {
142 ensureOpen();
143 if (b == null) {
144 throw new NullPointerException();
145 } else if (off < 0 || len < 0 || len > b.length - off) {
146 throw new IndexOutOfBoundsException();
147 } else if (len == 0) {
148 return 0;
149 }
150 try {
151 int n;
152 while ((n = inf.inflate(b, off, len)) == 0) {
153 if (inf.finished() || inf.needsDictionary()) {
154 reachEOF = true;
155 return -1;
156 }
157 if (inf.needsInput()) {
158 fill();
159 }
160 }
161 return n;
162 } catch (DataFormatException e) {
163 String s = e.getMessage();
164 throw new ZipException(s != null ? s : "Invalid ZLIB data format");
165 }
166 }
167
168 /**
169 * Returns 0 after EOF has been reached, otherwise always return 1.
170 * <p>
171 * Programs should not count on this method to return the actual number
172 * of bytes that could be read without blocking.
173 *
174 * @return 1 before EOF and 0 after EOF.
175 * @exception IOException if an I/O error occurs.
176 *
177 */
178 public int available() throws IOException {
179 ensureOpen();
180 if (reachEOF) {
181 return 0;
182 } else if (inf.finished()) {
183 // the end of the compressed data stream has been reached
184 reachEOF = true;
185 return 0;
186 } else {
187 return 1;
188 }
189 }
190
191 private byte[] b = new byte[512];
192
193 /**
194 * Skips specified number of bytes of uncompressed data.
195 * @param n the number of bytes to skip
196 * @return the actual number of bytes skipped.
197 * @exception IOException if an I/O error has occurred
198 * @exception IllegalArgumentException if {@code n < 0}
199 */
200 public long skip(long n) throws IOException {
201 if (n < 0) {
202 throw new IllegalArgumentException("negative skip length");
203 }
204 ensureOpen();
205 int max = (int)Math.min(n, Integer.MAX_VALUE);
206 int total = 0;
207 while (total < max) {
208 int len = max - total;
209 if (len > b.length) {
210 len = b.length;
211 }
212 len = read(b, 0, len);
213 if (len == -1) {
214 reachEOF = true;
215 break;
216 }
217 total += len;
218 }
219 return total;
220 }
221
222 /**
223 * Closes this input stream and releases any system resources associated
224 * with the stream.
225 * @exception IOException if an I/O error has occurred
226 */
227 public void close() throws IOException {
228 if (!closed) {
229 if (usesDefaultInflater)
230 inf.end();
231 in.close();
232 closed = true;
233 }
234 }
235
236 /**
237 * Fills input buffer with more data to decompress.
238 * @exception IOException if an I/O error has occurred
239 */
240 protected void fill() throws IOException {
241 ensureOpen();
242 len = in.read(buf, 0, buf.length);
243 if (len == -1) {
244 throw new EOFException("Unexpected end of ZLIB input stream");
245 }
246 inf.setInput(buf, 0, len);
247 }
248
249 /**
250 * Tests if this input stream supports the <code>mark</code> and
251 * <code>reset</code> methods. The <code>markSupported</code>
252 * method of <code>InflaterInputStream</code> returns
253 * <code>false</code>.
254 *
255 * @return a <code>boolean</code> indicating if this stream type supports
256 * the <code>mark</code> and <code>reset</code> methods.
257 * @see java.io.InputStream#mark(int)
258 * @see java.io.InputStream#reset()
259 */
260 public boolean markSupported() {
261 return false;
262 }
263
264 /**
265 * Marks the current position in this input stream.
266 *
267 * <p> The <code>mark</code> method of <code>InflaterInputStream</code>
268 * does nothing.
269 *
270 * @param readlimit the maximum limit of bytes that can be read before
271 * the mark position becomes invalid.
272 * @see java.io.InputStream#reset()
273 */
274 public synchronized void mark(int readlimit) {
275 }
276
277 /**
278 * Repositions this stream to the position at the time the
279 * <code>mark</code> method was last called on this input stream.
280 *
281 * <p> The method <code>reset</code> for class
282 * <code>InflaterInputStream</code> does nothing except throw an
283 * <code>IOException</code>.
284 *
285 * @exception IOException if this method is invoked.
286 * @see java.io.InputStream#mark(int)
287 * @see java.io.IOException
288 */
289 public synchronized void reset() throws IOException {
290 throw new IOException("mark/reset not supported");
291 }
292 }