source: trunk/vnc/vnc_javasrc/ZlibInStream.java @ 164

Last change on this file since 164 was 66, checked in by quentin, 17 years ago

Initial checkin of modified Java VNC viewer for use as remote console

File size: 3.1 KB
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1/* Copyright (C) 2002-2005 RealVNC Ltd.  All Rights Reserved.
2 *
3 * This is free software; you can redistribute it and/or modify
4 * it under the terms of the GNU General Public License as published by
5 * the Free Software Foundation; either version 2 of the License, or
6 * (at your option) any later version.
7 *
8 * This software 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 * You should have received a copy of the GNU General Public License
14 * along with this software; if not, write to the Free Software
15 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
16 * USA.
17 */
18
19//
20// A ZlibInStream reads from a zlib.io.InputStream
21//
22
23public class ZlibInStream extends InStream {
24
25  static final int defaultBufSize = 16384;
26
27  public ZlibInStream(int bufSize_) {
28    bufSize = bufSize_;
29    b = new byte[bufSize];
30    ptr = end = ptrOffset = 0;
31    inflater = new java.util.zip.Inflater();
32  }
33
34  public ZlibInStream() { this(defaultBufSize); }
35
36  public void setUnderlying(InStream is, int bytesIn_) {
37    underlying = is;
38    bytesIn = bytesIn_;
39    ptr = end = 0;
40  }
41
42  public void reset() throws Exception {
43    ptr = end = 0;
44    if (underlying == null) return;
45
46    while (bytesIn > 0) {
47      decompress();
48      end = 0; // throw away any data
49    }
50    underlying = null;
51  }
52
53  public int pos() { return ptrOffset + ptr; }
54
55  protected int overrun(int itemSize, int nItems) throws Exception {
56    if (itemSize > bufSize)
57      throw new Exception("ZlibInStream overrun: max itemSize exceeded");
58    if (underlying == null)
59      throw new Exception("ZlibInStream overrun: no underlying stream");
60
61    if (end - ptr != 0)
62      System.arraycopy(b, ptr, b, 0, end - ptr);
63
64    ptrOffset += ptr;
65    end -= ptr;
66    ptr = 0;
67
68    while (end < itemSize) {
69      decompress();
70    }
71
72    if (itemSize * nItems > end)
73      nItems = end / itemSize;
74
75    return nItems;
76  }
77
78  // decompress() calls the decompressor once.  Note that this won't
79  // necessarily generate any output data - it may just consume some input
80  // data.  Returns false if wait is false and we would block on the underlying
81  // stream.
82
83  private void decompress() throws Exception {
84    try {
85      underlying.check(1);
86      int avail_in = underlying.getend() - underlying.getptr();
87      if (avail_in > bytesIn)
88        avail_in = bytesIn;
89
90      if (inflater.needsInput()) {
91        inflater.setInput(underlying.getbuf(), underlying.getptr(), avail_in);
92      }
93
94      int n = inflater.inflate(b, end, bufSize - end); 
95
96      end += n;
97      if (inflater.needsInput()) {
98        bytesIn -= avail_in;
99        underlying.setptr(underlying.getptr() + avail_in);
100      }
101    } catch (java.util.zip.DataFormatException e) {
102      throw new Exception("ZlibInStream: inflate failed");
103    }
104  }
105
106  private InStream underlying;
107  private int bufSize;
108  private int ptrOffset;
109  private java.util.zip.Inflater inflater;
110  private int bytesIn;
111}
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