1 /*
2 * Copyright 1996-2006 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any 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 size is <= 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 : singleByteBuf[0] & 0xff;
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 {
183 return 1;
184 }
185 }
186
187 private byte[] b = new byte[512];
188
189 /**
190 * Skips specified number of bytes of uncompressed data.
191 * @param n the number of bytes to skip
192 * @return the actual number of bytes skipped.
193 * @exception IOException if an I/O error has occurred
194 * @exception IllegalArgumentException if n < 0
195 */
196 public long skip(long n) throws IOException {
197 if (n < 0) {
198 throw new IllegalArgumentException("negative skip length");
199 }
200 ensureOpen();
201 int max = (int)Math.min(n, Integer.MAX_VALUE);
202 int total = 0;
203 while (total < max) {
204 int len = max - total;
205 if (len > b.length) {
206 len = b.length;
207 }
208 len = read(b, 0, len);
209 if (len == -1) {
210 reachEOF = true;
211 break;
212 }
213 total += len;
214 }
215 return total;
216 }
217
218 /**
219 * Closes this input stream and releases any system resources associated
220 * with the stream.
221 * @exception IOException if an I/O error has occurred
222 */
223 public void close() throws IOException {
224 if (!closed) {
225 if (usesDefaultInflater)
226 inf.end();
227 in.close();
228 closed = true;
229 }
230 }
231
232 /**
233 * Fills input buffer with more data to decompress.
234 * @exception IOException if an I/O error has occurred
235 */
236 protected void fill() throws IOException {
237 ensureOpen();
238 len = in.read(buf, 0, buf.length);
239 if (len == -1) {
240 throw new EOFException("Unexpected end of ZLIB input stream");
241 }
242 inf.setInput(buf, 0, len);
243 }
244
245 /**
246 * Tests if this input stream supports the <code>mark</code> and
247 * <code>reset</code> methods. The <code>markSupported</code>
248 * method of <code>InflaterInputStream</code> returns
249 * <code>false</code>.
250 *
251 * @return a <code>boolean</code> indicating if this stream type supports
252 * the <code>mark</code> and <code>reset</code> methods.
253 * @see java.io.InputStream#mark(int)
254 * @see java.io.InputStream#reset()
255 */
256 public boolean markSupported() {
257 return false;
258 }
259
260 /**
261 * Marks the current position in this input stream.
262 *
263 * <p> The <code>mark</code> method of <code>InflaterInputStream</code>
264 * does nothing.
265 *
266 * @param readlimit the maximum limit of bytes that can be read before
267 * the mark position becomes invalid.
268 * @see java.io.InputStream#reset()
269 */
270 public synchronized void mark(int readlimit) {
271 }
272
273 /**
274 * Repositions this stream to the position at the time the
275 * <code>mark</code> method was last called on this input stream.
276 *
277 * <p> The method <code>reset</code> for class
278 * <code>InflaterInputStream</code> does nothing except throw an
279 * <code>IOException</code>.
280 *
281 * @exception IOException if this method is invoked.
282 * @see java.io.InputStream#mark(int)
283 * @see java.io.IOException
284 */
285 public synchronized void reset() throws IOException {
286 throw new IOException("mark/reset not supported");
287 }
288 }
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