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 * @since 1.1
41 */
42 public
43 class InflaterInputStream extends FilterInputStream {
44 /**
45 * Decompressor for this stream.
46 */
47 protected Inflater inf;
48
49 /**
50 * Input buffer for decompression.
51 */
52 protected byte[] buf;
53
54 /**
55 * Length of input buffer.
56 */
57 protected int len;
58
59 private boolean closed = false;
60 // this flag is set to true after EOF has reached
61 private boolean reachEOF = false;
62
63 /**
64 * Check to make sure that this stream has not been closed
65 */
66 private void ensureOpen() throws IOException {
67 if (closed) {
68 throw new IOException("Stream closed");
69 }
70 }
71
72
73 /**
74 * Creates a new input stream with the specified decompressor and
75 * buffer size.
76 * @param in the input stream
77 * @param inf the decompressor ("inflater")
78 * @param size the input buffer size
79 * @exception IllegalArgumentException if {@code size <= 0}
80 */
81 public InflaterInputStream(InputStream in, Inflater inf, int size) {
82 super(in);
83 if (in == null || inf == null) {
84 throw new NullPointerException();
85 } else if (size <= 0) {
86 throw new IllegalArgumentException("buffer size <= 0");
87 }
88 this.inf = inf;
89 buf = new byte[size];
90 }
91
92 /**
93 * Creates a new input stream with the specified decompressor and a
94 * default buffer size.
95 * @param in the input stream
96 * @param inf the decompressor ("inflater")
97 */
98 public InflaterInputStream(InputStream in, Inflater inf) {
99 this(in, inf, 512);
100 }
101
102 boolean usesDefaultInflater = false;
103
104 /**
105 * Creates a new input stream with a default decompressor and buffer size.
106 * @param in the input stream
107 */
108 public InflaterInputStream(InputStream in) {
109 this(in, new Inflater());
110 usesDefaultInflater = true;
111 }
112
113 private byte[] singleByteBuf = new byte[1];
114
115 /**
116 * Reads a byte of uncompressed data. This method will block until
117 * enough input is available for decompression.
118 * @return the byte read, or -1 if end of compressed input is reached
119 * @exception IOException if an I/O error has occurred
120 */
121 public int read() throws IOException {
122 ensureOpen();
123 return read(singleByteBuf, 0, 1) == -1 ? -1 : Byte.toUnsignedInt(singleByteBuf[0]);
124 }
125
126 /**
127 * Reads uncompressed data into an array of bytes. If <code>len</code> is not
128 * zero, the method will block until some input can be decompressed; otherwise,
129 * no bytes are read and <code>0</code> is returned.
130 * @param b the buffer into which the data is read
131 * @param off the start offset in the destination array <code>b</code>
132 * @param len the maximum number of bytes read
133 * @return the actual number of bytes read, or -1 if the end of the
134 * compressed input is reached or a preset dictionary is needed
135 * @exception NullPointerException If <code>b</code> is <code>null</code>.
136 * @exception IndexOutOfBoundsException If <code>off</code> is negative,
137 * <code>len</code> is negative, or <code>len</code> is greater than
138 * <code>b.length - off</code>
139 * @exception ZipException if a ZIP format error has occurred
140 * @exception IOException if an I/O error has occurred
141 */
142 public int read(byte[] b, int off, int len) throws IOException {
143 ensureOpen();
144 if (b == null) {
145 throw new NullPointerException();
146 } else if (off < 0 || len < 0 || len > b.length - off) {
147 throw new IndexOutOfBoundsException();
148 } else if (len == 0) {
149 return 0;
150 }
151 try {
152 int n;
153 while ((n = inf.inflate(b, off, len)) == 0) {
154 if (inf.finished() || inf.needsDictionary()) {
155 reachEOF = true;
156 return -1;
157 }
158 if (inf.needsInput()) {
159 fill();
160 }
161 }
162 return n;
163 } catch (DataFormatException e) {
164 String s = e.getMessage();
165 throw new ZipException(s != null ? s : "Invalid ZLIB data format");
166 }
167 }
168
169 /**
170 * Returns 0 after EOF has been reached, otherwise always return 1.
171 * <p>
172 * Programs should not count on this method to return the actual number
173 * of bytes that could be read without blocking.
174 *
175 * @return 1 before EOF and 0 after EOF.
176 * @exception IOException if an I/O error occurs.
177 *
178 */
179 public int available() throws IOException {
180 ensureOpen();
181 if (reachEOF) {
182 return 0;
183 } else if (inf.finished()) {
184 // the end of the compressed data stream has been reached
185 reachEOF = true;
186 return 0;
187 } else {
188 return 1;
189 }
190 }
191
192 private byte[] b = new byte[512];
193
194 /**
195 * Skips specified number of bytes of uncompressed data.
196 * @param n the number of bytes to skip
197 * @return the actual number of bytes skipped.
198 * @exception IOException if an I/O error has occurred
199 * @exception IllegalArgumentException if {@code n < 0}
200 */
201 public long skip(long n) throws IOException {
202 if (n < 0) {
203 throw new IllegalArgumentException("negative skip length");
204 }
205 ensureOpen();
206 int max = (int)Math.min(n, Integer.MAX_VALUE);
207 int total = 0;
208 while (total < max) {
209 int len = max - total;
210 if (len > b.length) {
211 len = b.length;
212 }
213 len = read(b, 0, len);
214 if (len == -1) {
215 reachEOF = true;
216 break;
217 }
218 total += len;
219 }
220 return total;
221 }
222
223 /**
224 * Closes this input stream and releases any system resources associated
225 * with the stream.
226 * @exception IOException if an I/O error has occurred
227 */
228 public void close() throws IOException {
229 if (!closed) {
230 if (usesDefaultInflater)
231 inf.end();
232 in.close();
233 closed = true;
234 }
235 }
236
237 /**
238 * Fills input buffer with more data to decompress.
239 * @exception IOException if an I/O error has occurred
240 */
241 protected void fill() throws IOException {
242 ensureOpen();
243 len = in.read(buf, 0, buf.length);
244 if (len == -1) {
245 throw new EOFException("Unexpected end of ZLIB input stream");
246 }
247 inf.setInput(buf, 0, len);
248 }
249
250 /**
251 * Tests if this input stream supports the <code>mark</code> and
252 * <code>reset</code> methods. The <code>markSupported</code>
253 * method of <code>InflaterInputStream</code> returns
254 * <code>false</code>.
255 *
256 * @return a <code>boolean</code> indicating if this stream type supports
257 * the <code>mark</code> and <code>reset</code> methods.
258 * @see java.io.InputStream#mark(int)
259 * @see java.io.InputStream#reset()
260 */
261 public boolean markSupported() {
262 return false;
263 }
264
265 /**
266 * Marks the current position in this input stream.
267 *
268 * <p> The <code>mark</code> method of <code>InflaterInputStream</code>
269 * does nothing.
270 *
271 * @param readlimit the maximum limit of bytes that can be read before
272 * the mark position becomes invalid.
273 * @see java.io.InputStream#reset()
274 */
275 public synchronized void mark(int readlimit) {
276 }
277
278 /**
279 * Repositions this stream to the position at the time the
280 * <code>mark</code> method was last called on this input stream.
281 *
282 * <p> The method <code>reset</code> for class
283 * <code>InflaterInputStream</code> does nothing except throw an
284 * <code>IOException</code>.
285 *
286 * @exception IOException if this method is invoked.
287 * @see java.io.InputStream#mark(int)
288 * @see java.io.IOException
289 */
290 public synchronized void reset() throws IOException {
291 throw new IOException("mark/reset not supported");
292 }
293 }