Mercurial > hg4j

comparison hg4j/src/main/java/org/tmatesoft/hg/internal/InflaterDataAccess.java @ 213:6ec4af642ba8 gradle

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Project uses Gradle for build - actual changes
author Alexander Kitaev <kitaev@gmail.com>
date Tue, 10 May 2011 10:52:53 +0200
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212:edb2e2829352 213:6ec4af642ba8
1 /*
2 * Copyright (c) 2011 TMate Software Ltd
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; version 2 of the License.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * For information on how to redistribute this software under
14 * the terms of a license other than GNU General Public License
15 * contact TMate Software at support@hg4j.com
16 */
17 package org.tmatesoft.hg.internal;
18
19 import java.io.EOFException;
20 import java.io.IOException;
21 import java.util.zip.DataFormatException;
22 import java.util.zip.Inflater;
23 import java.util.zip.ZipException;
24
25 import org.tmatesoft.hg.core.HgBadStateException;
26
27
28 /**
29 * DataAccess counterpart for InflaterInputStream.
30 * XXX is it really needed to be subclass of FilterDataAccess?
31 *
32 * @author Artem Tikhomirov
33 * @author TMate Software Ltd.
34 */
35 public class InflaterDataAccess extends FilterDataAccess {
36
37 private final Inflater inflater;
38 private final byte[] buffer;
39 private final byte[] singleByte = new byte[1];
40 private int decompressedPos = 0;
41 private int decompressedLength;
42
43 public InflaterDataAccess(DataAccess dataAccess, int offset, int compressedLength) {
44 this(dataAccess, offset, compressedLength, -1, new Inflater(), 512);
45 }
46
47 public InflaterDataAccess(DataAccess dataAccess, int offset, int compressedLength, int actualLength) {
48 this(dataAccess, offset, compressedLength, actualLength, new Inflater(), 512);
49 }
50
51 public InflaterDataAccess(DataAccess dataAccess, int offset, int compressedLength, int actualLength, Inflater inflater, int bufSize) {
52 super(dataAccess, offset, compressedLength);
53 this.inflater = inflater;
54 this.decompressedLength = actualLength;
55 buffer = new byte[bufSize];
56 }
57
58 @Override
59 public InflaterDataAccess reset() throws IOException {
60 super.reset();
61 inflater.reset();
62 decompressedPos = 0;
63 return this;
64 }
65
66 @Override
67 protected int available() {
68 return length() - decompressedPos;
69 }
70
71 @Override
72 public boolean isEmpty() {
73 // can't use super.available() <= 0 because even when 0 < super.count < 6(?)
74 // decompressedPos might be already == length()
75 return available() <= 0;
76 }
77
78 @Override
79 public int length() {
80 if (decompressedLength != -1) {
81 return decompressedLength;
82 }
83 decompressedLength = 0; // guard to avoid endless loop in case length() would get invoked from below.
84 int c = 0;
85 try {
86 int oldPos = decompressedPos;
87 byte[] dummy = new byte[buffer.length];
88 int toRead;
89 while ((toRead = super.available()) > 0) {
90 if (toRead > buffer.length) {
91 toRead = buffer.length;
92 }
93 super.readBytes(buffer, 0, toRead);
94 inflater.setInput(buffer, 0, toRead);
95 try {
96 while (!inflater.needsInput()) {
97 c += inflater.inflate(dummy, 0, dummy.length);
98 }
99 } catch (DataFormatException ex) {
100 throw new HgBadStateException(ex);
101 }
102 }
103 decompressedLength = c + oldPos;
104 reset();
105 seek(oldPos);
106 return decompressedLength;
107 } catch (IOException ex) {
108 decompressedLength = -1; // better luck next time?
109 throw new HgBadStateException(ex); // XXX perhaps, checked exception
110 }
111 }
112
113 @Override
114 public void seek(int localOffset) throws IOException {
115 if (localOffset < 0 /* || localOffset >= length() */) {
116 throw new IllegalArgumentException();
117 }
118 if (localOffset >= decompressedPos) {
119 skip((int) (localOffset - decompressedPos));
120 } else {
121 reset();
122 skip((int) localOffset);
123 }
124 }
125
126 @Override
127 public void skip(int bytes) throws IOException {
128 if (bytes < 0) {
129 bytes += decompressedPos;
130 if (bytes < 0) {
131 throw new IOException("Underflow. Rewind past start of the slice.");
132 }
133 reset();
134 // fall-through
135 }
136 while (!isEmpty() && bytes > 0) {
137 readByte();
138 bytes--;
139 }
140 if (bytes != 0) {
141 throw new IOException("Underflow. Rewind past end of the slice");
142 }
143 }
144
145 @Override
146 public byte readByte() throws IOException {
147 readBytes(singleByte, 0, 1);
148 return singleByte[0];
149 }
150
151 @Override
152 public void readBytes(byte[] b, int off, int len) throws IOException {
153 try {
154 int n;
155 while (len > 0) {
156 while ((n = inflater.inflate(b, off, len)) == 0) {
157 // FIXME few last bytes (checksum?) may be ignored by inflater, thus inflate may return 0 in
158 // perfectly legal conditions (when all data already expanded, but there are still some bytes
159 // in the input stream
160 if (inflater.finished() || inflater.needsDictionary()) {
161 throw new EOFException();
162 }
163 if (inflater.needsInput()) {
164 // fill:
165 int toRead = super.available();
166 if (toRead > buffer.length) {
167 toRead = buffer.length;
168 }
169 super.readBytes(buffer, 0, toRead);
170 inflater.setInput(buffer, 0, toRead);
171 }
172 }
173 off += n;
174 len -= n;
175 decompressedPos += n;
176 if (len == 0) {
177 return; // filled
178 }
179 }
180 } catch (DataFormatException e) {
181 String s = e.getMessage();
182 throw new ZipException(s != null ? s : "Invalid ZLIB data format");
183 }
184 }
185 }