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1 /* Copyright (C) 2002-2005 RealVNC Ltd. All Rights Reserved.
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2 *
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3 * This is free software; you can redistribute it and/or modify
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4 * it under the terms of the GNU General Public License as published by
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5 * the Free Software Foundation; either version 2 of the License, or
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6 * (at your option) any later version.
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7 *
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8 * This software is distributed in the hope that it will be useful,
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9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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11 * GNU General Public License for more details.
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12 *
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13 * You should have received a copy of the GNU General Public License
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14 * along with this software; if not, write to the Free Software
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15 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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16 * USA.
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17 */
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18
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19 //
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20 // A ZlibInStream reads from a zlib.io.InputStream
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21 //
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22
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23 public class ZlibInStream extends InStream {
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24
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25 static final int defaultBufSize = 16384;
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26
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27 public ZlibInStream(int bufSize_) {
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28 bufSize = bufSize_;
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29 b = new byte[bufSize];
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30 ptr = end = ptrOffset = 0;
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31 inflater = new java.util.zip.Inflater();
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32 }
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33
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34 public ZlibInStream() { this(defaultBufSize); }
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35
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36 public void setUnderlying(InStream is, int bytesIn_) {
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37 underlying = is;
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38 bytesIn = bytesIn_;
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39 ptr = end = 0;
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40 }
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41
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42 public void reset() throws Exception {
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43 ptr = end = 0;
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44 if (underlying == null) return;
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45
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46 while (bytesIn > 0) {
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47 decompress();
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48 end = 0; // throw away any data
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49 }
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50 underlying = null;
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51 }
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52
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53 public int pos() { return ptrOffset + ptr; }
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54
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55 protected int overrun(int itemSize, int nItems) throws Exception {
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56 if (itemSize > bufSize)
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57 throw new Exception("ZlibInStream overrun: max itemSize exceeded");
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58 if (underlying == null)
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59 throw new Exception("ZlibInStream overrun: no underlying stream");
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60
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61 if (end - ptr != 0)
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62 System.arraycopy(b, ptr, b, 0, end - ptr);
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63
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64 ptrOffset += ptr;
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65 end -= ptr;
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66 ptr = 0;
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67
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68 while (end < itemSize) {
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69 decompress();
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70 }
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71
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72 if (itemSize * nItems > end)
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73 nItems = end / itemSize;
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74
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75 return nItems;
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76 }
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77
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78 // decompress() calls the decompressor once. Note that this won't
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79 // necessarily generate any output data - it may just consume some input
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80 // data. Returns false if wait is false and we would block on the underlying
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81 // stream.
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82
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83 private void decompress() throws Exception {
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84 try {
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85 underlying.check(1);
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86 int avail_in = underlying.getend() - underlying.getptr();
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87 if (avail_in > bytesIn)
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88 avail_in = bytesIn;
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89
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90 if (inflater.needsInput()) {
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91 inflater.setInput(underlying.getbuf(), underlying.getptr(), avail_in);
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92 }
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93
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94 int n = inflater.inflate(b, end, bufSize - end);
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95
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96 end += n;
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97 if (inflater.needsInput()) {
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98 bytesIn -= avail_in;
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99 underlying.setptr(underlying.getptr() + avail_in);
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100 }
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101 } catch (java.util.zip.DataFormatException e) {
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102 throw new Exception("ZlibInStream: inflate failed");
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103 }
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104 }
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105
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106 private InStream underlying;
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107 private int bufSize;
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108 private int ptrOffset;
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109 private java.util.zip.Inflater inflater;
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110 private int bytesIn;
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111 }
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