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comparison src/com/trilead/ssh2/compression/Zlib.java @ 0:0ce5cc452d02

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initial version
author Carl Byington <carl@five-ten-sg.com>
date Thu, 22 May 2014 10:41:19 -0700
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-1:000000000000 0:0ce5cc452d02
1 /*
2 * ConnectBot: simple, powerful, open-source SSH client for Android
3 * Copyright 2007 Kenny Root, Jeffrey Sharkey
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package com.trilead.ssh2.compression;
19
20 import com.jcraft.jzlib.JZlib;
21 import com.jcraft.jzlib.ZStream;
22
23 /**
24 * @author Kenny Root
25 *
26 */
27 public class Zlib implements ICompressor {
28 static private final int DEFAULT_BUF_SIZE = 4096;
29 static private final int LEVEL = 5;
30
31 private ZStream deflate;
32 private byte[] deflate_tmpbuf;
33
34 private ZStream inflate;
35 private byte[] inflate_tmpbuf;
36 private byte[] inflated_buf;
37
38 public Zlib() {
39 deflate = new ZStream();
40 inflate = new ZStream();
41 deflate.deflateInit(LEVEL);
42 inflate.inflateInit();
43 deflate_tmpbuf = new byte[DEFAULT_BUF_SIZE];
44 inflate_tmpbuf = new byte[DEFAULT_BUF_SIZE];
45 inflated_buf = new byte[DEFAULT_BUF_SIZE];
46 }
47
48 public boolean canCompressPreauth() {
49 return true;
50 }
51
52 public int getBufferSize() {
53 return DEFAULT_BUF_SIZE;
54 }
55
56 public int compress(byte[] buf, int start, int len, byte[] output) {
57 deflate.next_in = buf;
58 deflate.next_in_index = start;
59 deflate.avail_in = len - start;
60
61 if ((buf.length + 1024) > deflate_tmpbuf.length) {
62 deflate_tmpbuf = new byte[buf.length + 1024];
63 }
64
65 deflate.next_out = deflate_tmpbuf;
66 deflate.next_out_index = 0;
67 deflate.avail_out = output.length;
68
69 if (deflate.deflate(JZlib.Z_PARTIAL_FLUSH) != JZlib.Z_OK) {
70 System.err.println("compress: compression failure");
71 }
72
73 if (deflate.avail_in > 0) {
74 System.err.println("compress: deflated data too large");
75 }
76
77 int outputlen = output.length - deflate.avail_out;
78 System.arraycopy(deflate_tmpbuf, 0, output, 0, outputlen);
79 return outputlen;
80 }
81
82 public byte[] uncompress(byte[] buffer, int start, int[] length) {
83 int inflated_end = 0;
84 inflate.next_in = buffer;
85 inflate.next_in_index = start;
86 inflate.avail_in = length[0];
87
88 while (true) {
89 inflate.next_out = inflate_tmpbuf;
90 inflate.next_out_index = 0;
91 inflate.avail_out = DEFAULT_BUF_SIZE;
92 int status = inflate.inflate(JZlib.Z_PARTIAL_FLUSH);
93
94 switch (status) {
95 case JZlib.Z_OK:
96 if (inflated_buf.length < inflated_end + DEFAULT_BUF_SIZE
97 - inflate.avail_out) {
98 byte[] foo = new byte[inflated_end + DEFAULT_BUF_SIZE
99 - inflate.avail_out];
100 System.arraycopy(inflated_buf, 0, foo, 0, inflated_end);
101 inflated_buf = foo;
102 }
103
104 System.arraycopy(inflate_tmpbuf, 0, inflated_buf, inflated_end,
105 DEFAULT_BUF_SIZE - inflate.avail_out);
106 inflated_end += (DEFAULT_BUF_SIZE - inflate.avail_out);
107 length[0] = inflated_end;
108 break;
109
110 case JZlib.Z_BUF_ERROR:
111 if (inflated_end > buffer.length - start) {
112 byte[] foo = new byte[inflated_end + start];
113 System.arraycopy(buffer, 0, foo, 0, start);
114 System.arraycopy(inflated_buf, 0, foo, start, inflated_end);
115 buffer = foo;
116 }
117 else {
118 System.arraycopy(inflated_buf, 0, buffer, start,
119 inflated_end);
120 }
121
122 length[0] = inflated_end;
123 return buffer;
124
125 default:
126 System.err.println("uncompress: inflate returnd " + status);
127 return null;
128 }
129 }
130 }
131 }