source: trunk/packages/invirt-vnc-client/ZlibInStream.java @ 2101

Last change on this file since 2101 was 1334, checked in by broder, 16 years ago

sipb-xen-vnc-client -> invirt-vnc-client

File size: 3.1 KB
Line 
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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