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annotate src/ch/ethz/ssh2/compression/Zlib.java @ 380:162c001c8142

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fix url link in help file
author Carl Byington <carl@five-ten-sg.com>
date Mon, 04 Aug 2014 15:25:34 -0700
parents 9a657362519c
children
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1 /*
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2 * ConnectBot: simple, powerful, open-source SSH client for Android
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3 * Copyright 2007 Kenny Root, Jeffrey Sharkey
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4 *
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5 * Licensed under the Apache License, Version 2.0 (the "License");
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6 * you may not use this file except in compliance with the License.
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7 * You may obtain a copy of the License at
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8 *
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9 * http://www.apache.org/licenses/LICENSE-2.0
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10 *
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11 * Unless required by applicable law or agreed to in writing, software
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12 * distributed under the License is distributed on an "AS IS" BASIS,
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13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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14 * See the License for the specific language governing permissions and
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15 * limitations under the License.
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16 */
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17
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18 package ch.ethz.ssh2.compression;
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19
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20 import com.jcraft.jzlib.JZlib;
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21 import com.jcraft.jzlib.ZStream;
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22
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23 /**
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24 * @author Kenny Root
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25 *
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26 */
327
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27 public class Zlib implements Compressor {
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28 static private final int DEFAULT_BUF_SIZE = 4096;
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29 static private final int LEVEL = 5;
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30
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31 private ZStream deflate;
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32 private byte[] deflate_tmpbuf;
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33
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34 private ZStream inflate;
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35 private byte[] inflate_tmpbuf;
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36 private byte[] inflated_buf;
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37
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38 public Zlib() {
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39 deflate = new ZStream();
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40 inflate = new ZStream();
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41 deflate.deflateInit(LEVEL);
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42 inflate.inflateInit();
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43 deflate_tmpbuf = new byte[DEFAULT_BUF_SIZE];
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44 inflate_tmpbuf = new byte[DEFAULT_BUF_SIZE];
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45 inflated_buf = new byte[DEFAULT_BUF_SIZE];
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46 }
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47
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48 public boolean canCompressPreauth() {
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49 return true;
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50 }
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51
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52 public int getBufferSize() {
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53 return DEFAULT_BUF_SIZE;
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54 }
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55
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56 public int compress(byte[] buf, int start, int len, byte[] output) {
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57 deflate.next_in = buf;
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58 deflate.next_in_index = start;
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59 deflate.avail_in = len - start;
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60
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61 if ((buf.length + 1024) > deflate_tmpbuf.length) {
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62 deflate_tmpbuf = new byte[buf.length + 1024];
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63 }
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64
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65 deflate.next_out = deflate_tmpbuf;
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66 deflate.next_out_index = 0;
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67 deflate.avail_out = output.length;
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68
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69 if (deflate.deflate(JZlib.Z_PARTIAL_FLUSH) != JZlib.Z_OK) {
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70 System.err.println("compress: compression failure");
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71 }
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72
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73 if (deflate.avail_in > 0) {
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74 System.err.println("compress: deflated data too large");
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75 }
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76
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77 int outputlen = output.length - deflate.avail_out;
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78 System.arraycopy(deflate_tmpbuf, 0, output, 0, outputlen);
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79 return outputlen;
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80 }
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81
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82 public byte[] uncompress(byte[] buffer, int start, int[] length) {
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83 int inflated_end = 0;
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84 inflate.next_in = buffer;
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85 inflate.next_in_index = start;
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86 inflate.avail_in = length[0];
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87
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88 while (true) {
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89 inflate.next_out = inflate_tmpbuf;
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90 inflate.next_out_index = 0;
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91 inflate.avail_out = DEFAULT_BUF_SIZE;
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92 int status = inflate.inflate(JZlib.Z_PARTIAL_FLUSH);
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93
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94 switch (status) {
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95 case JZlib.Z_OK:
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96 if (inflated_buf.length < inflated_end + DEFAULT_BUF_SIZE
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97 - inflate.avail_out) {
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98 byte[] foo = new byte[inflated_end + DEFAULT_BUF_SIZE
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99 - inflate.avail_out];
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100 System.arraycopy(inflated_buf, 0, foo, 0, inflated_end);
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101 inflated_buf = foo;
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102 }
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103
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104 System.arraycopy(inflate_tmpbuf, 0, inflated_buf, inflated_end,
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105 DEFAULT_BUF_SIZE - inflate.avail_out);
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106 inflated_end += (DEFAULT_BUF_SIZE - inflate.avail_out);
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107 length[0] = inflated_end;
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108 break;
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109
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110 case JZlib.Z_BUF_ERROR:
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111 if (inflated_end > buffer.length - start) {
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112 byte[] foo = new byte[inflated_end + start];
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113 System.arraycopy(buffer, 0, foo, 0, start);
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114 System.arraycopy(inflated_buf, 0, foo, start, inflated_end);
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115 buffer = foo;
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116 }
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117 else {
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118 System.arraycopy(inflated_buf, 0, buffer, start,
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119 inflated_end);
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120 }
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121
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122 length[0] = inflated_end;
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123 return buffer;
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124
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125 default:
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126 System.err.println("uncompress: inflate returnd " + status);
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127 return null;
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128 }
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129 }
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130 }
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131 }