001 /*
002 * Copyright 1996-2006 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package java.util.zip;
027
028 import java.io.FilterInputStream;
029 import java.io.InputStream;
030 import java.io.IOException;
031 import java.io.EOFException;
032
033 /**
034 * This class implements a stream filter for uncompressing data in the
035 * "deflate" compression format. It is also used as the basis for other
036 * decompression filters, such as GZIPInputStream.
037 *
038 * @see Inflater
039 * @version 1.46, 05/05/07
040 * @author David Connelly
041 */
042 public class InflaterInputStream extends FilterInputStream {
043 /**
044 * Decompressor for this stream.
045 */
046 protected Inflater inf;
047
048 /**
049 * Input buffer for decompression.
050 */
051 protected byte[] buf;
052
053 /**
054 * Length of input buffer.
055 */
056 protected int len;
057
058 private boolean closed = false;
059 // this flag is set to true after EOF has reached
060 private boolean reachEOF = false;
061
062 /**
063 * Check to make sure that this stream has not been closed
064 */
065 private void ensureOpen() throws IOException {
066 if (closed) {
067 throw new IOException("Stream closed");
068 }
069 }
070
071 /**
072 * Creates a new input stream with the specified decompressor and
073 * buffer size.
074 * @param in the input stream
075 * @param inf the decompressor ("inflater")
076 * @param size the input buffer size
077 * @exception IllegalArgumentException if size is <= 0
078 */
079 public InflaterInputStream(InputStream in, Inflater inf, int size) {
080 super (in);
081 if (in == null || inf == null) {
082 throw new NullPointerException();
083 } else if (size <= 0) {
084 throw new IllegalArgumentException("buffer size <= 0");
085 }
086 this .inf = inf;
087 buf = new byte[size];
088 }
089
090 /**
091 * Creates a new input stream with the specified decompressor and a
092 * default buffer size.
093 * @param in the input stream
094 * @param inf the decompressor ("inflater")
095 */
096 public InflaterInputStream(InputStream in, Inflater inf) {
097 this (in, inf, 512);
098 }
099
100 boolean usesDefaultInflater = false;
101
102 /**
103 * Creates a new input stream with a default decompressor and buffer size.
104 * @param in the input stream
105 */
106 public InflaterInputStream(InputStream in) {
107 this (in, new Inflater());
108 usesDefaultInflater = true;
109 }
110
111 private byte[] singleByteBuf = new byte[1];
112
113 /**
114 * Reads a byte of uncompressed data. This method will block until
115 * enough input is available for decompression.
116 * @return the byte read, or -1 if end of compressed input is reached
117 * @exception IOException if an I/O error has occurred
118 */
119 public int read() throws IOException {
120 ensureOpen();
121 return read(singleByteBuf, 0, 1) == -1 ? -1
122 : 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
165 : "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 {
184 return 1;
185 }
186 }
187
188 private byte[] b = new byte[512];
189
190 /**
191 * Skips specified number of bytes of uncompressed data.
192 * @param n the number of bytes to skip
193 * @return the actual number of bytes skipped.
194 * @exception IOException if an I/O error has occurred
195 * @exception IllegalArgumentException if n < 0
196 */
197 public long skip(long n) throws IOException {
198 if (n < 0) {
199 throw new IllegalArgumentException("negative skip length");
200 }
201 ensureOpen();
202 int max = (int) Math.min(n, Integer.MAX_VALUE);
203 int total = 0;
204 while (total < max) {
205 int len = max - total;
206 if (len > b.length) {
207 len = b.length;
208 }
209 len = read(b, 0, len);
210 if (len == -1) {
211 reachEOF = true;
212 break;
213 }
214 total += len;
215 }
216 return total;
217 }
218
219 /**
220 * Closes this input stream and releases any system resources associated
221 * with the stream.
222 * @exception IOException if an I/O error has occurred
223 */
224 public void close() throws IOException {
225 if (!closed) {
226 if (usesDefaultInflater)
227 inf.end();
228 in.close();
229 closed = true;
230 }
231 }
232
233 /**
234 * Fills input buffer with more data to decompress.
235 * @exception IOException if an I/O error has occurred
236 */
237 protected void fill() throws IOException {
238 ensureOpen();
239 len = in.read(buf, 0, buf.length);
240 if (len == -1) {
241 throw new EOFException(
242 "Unexpected end of ZLIB input stream");
243 }
244 inf.setInput(buf, 0, len);
245 }
246
247 /**
248 * Tests if this input stream supports the <code>mark</code> and
249 * <code>reset</code> methods. The <code>markSupported</code>
250 * method of <code>InflaterInputStream</code> returns
251 * <code>false</code>.
252 *
253 * @return a <code>boolean</code> indicating if this stream type supports
254 * the <code>mark</code> and <code>reset</code> methods.
255 * @see java.io.InputStream#mark(int)
256 * @see java.io.InputStream#reset()
257 */
258 public boolean markSupported() {
259 return false;
260 }
261
262 /**
263 * Marks the current position in this input stream.
264 *
265 * <p> The <code>mark</code> method of <code>InflaterInputStream</code>
266 * does nothing.
267 *
268 * @param readlimit the maximum limit of bytes that can be read before
269 * the mark position becomes invalid.
270 * @see java.io.InputStream#reset()
271 */
272 public synchronized void mark(int readlimit) {
273 }
274
275 /**
276 * Repositions this stream to the position at the time the
277 * <code>mark</code> method was last called on this input stream.
278 *
279 * <p> The method <code>reset</code> for class
280 * <code>InflaterInputStream</code> does nothing except throw an
281 * <code>IOException</code>.
282 *
283 * @exception IOException if this method is invoked.
284 * @see java.io.InputStream#mark(int)
285 * @see java.io.IOException
286 */
287 public synchronized void reset() throws IOException {
288 throw new IOException("mark/reset not supported");
289 }
290 }
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