comparison src/treeVnc/InStream.java @ 0:756bfaf731f3

create new repository
author Yu Taninari <you@cr.ie.u-ryukyu.ac.jp>
date Tue, 21 Feb 2012 04:10:12 +0900
parents
children
comparison
equal deleted inserted replaced
-1:000000000000 0:756bfaf731f3
1 package treeVnc;
2 /* Copyright (C) 2002-2005 RealVNC Ltd. All Rights Reserved.
3 *
4 * This is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This software is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this software; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
17 * USA.
18 */
19
20 //
21 // rdr::InStream marshalls data from a buffer stored in RDR (RFB Data
22 // Representation).
23 //
24
25 abstract public class InStream {
26
27 // check() ensures there is buffer data for at least one item of size
28 // itemSize bytes. Returns the number of items in the buffer (up to a
29 // maximum of nItems).
30
31 public final int check(int itemSize, int nItems) throws Exception {
32 if (ptr + itemSize * nItems > end) {
33 if (ptr + itemSize > end)
34 return overrun(itemSize, nItems);
35
36 nItems = (end - ptr) / itemSize;
37 }
38 return nItems;
39 }
40
41 public final void check(int itemSize) throws Exception {
42 if (ptr + itemSize > end)
43 overrun(itemSize, 1);
44 }
45
46 // readU/SN() methods read unsigned and signed N-bit integers.
47
48 public final int readS8() throws Exception {
49 check(1); return b[ptr++];
50 }
51
52 public final int readS16() throws Exception {
53 check(2); int b0 = b[ptr++];
54 int b1 = b[ptr++] & 0xff; return b0 << 8 | b1;
55 }
56
57 public final int readS32() throws Exception {
58 check(4); int b0 = b[ptr++];
59 int b1 = b[ptr++] & 0xff;
60 int b2 = b[ptr++] & 0xff;
61 int b3 = b[ptr++] & 0xff;
62 return b0 << 24 | b1 << 16 | b2 << 8 | b3;
63 }
64
65 public final int readU8() throws Exception {
66 return readS8() & 0xff;
67 }
68
69 public final int readU16() throws Exception {
70 return readS16() & 0xffff;
71 }
72
73 public final int readU32() throws Exception {
74 return readS32() & 0xffffffff;
75 }
76
77 // readString() reads a string - a U32 length followed by the data.
78
79 public final String readString() throws Exception {
80 int len = readU32();
81 if (len > maxStringLength)
82 throw new Exception("InStream max string length exceeded");
83
84 char[] str = new char[len];
85 int i = 0;
86 while (i < len) {
87 int j = i + check(1, len - i);
88 while (i < j) {
89 str[i++] = (char)b[ptr++];
90 }
91 }
92
93 return new String(str);
94 }
95
96 // maxStringLength protects against allocating a huge buffer. Set it
97 // higher if you need longer strings.
98
99 public static int maxStringLength = 65535;
100
101 public final void skip(int bytes) throws Exception {
102 while (bytes > 0) {
103 int n = check(1, bytes);
104 ptr += n;
105 bytes -= n;
106 }
107 }
108
109 // readBytes() reads an exact number of bytes into an array at an offset.
110
111 public void readBytes(byte[] data, int offset, int length) throws Exception {
112 int offsetEnd = offset + length;
113 while (offset < offsetEnd) {
114 int n = check(1, offsetEnd - offset);
115 System.arraycopy(b, ptr, data, offset, n);
116 ptr += n;
117 offset += n;
118 }
119 }
120
121 // readOpaqueN() reads a quantity "without byte-swapping". Because java has
122 // no byte-ordering, we just use big-endian.
123
124 public final int readOpaque8() throws Exception {
125 return readU8();
126 }
127
128 public final int readOpaque16() throws Exception {
129 return readU16();
130 }
131
132 public final int readOpaque32() throws Exception {
133 return readU32();
134 }
135
136 public final int readOpaque24A() throws Exception {
137 check(3); int b0 = b[ptr++];
138 int b1 = b[ptr++]; int b2 = b[ptr++];
139 return b0 << 24 | b1 << 16 | b2 << 8;
140 }
141
142 public final int readOpaque24B() throws Exception {
143 check(3); int b0 = b[ptr++];
144 int b1 = b[ptr++]; int b2 = b[ptr++];
145 return b0 << 16 | b1 << 8 | b2;
146 }
147
148 // pos() returns the position in the stream.
149
150 abstract public int pos();
151
152 // bytesAvailable() returns true if at least one byte can be read from the
153 // stream without blocking. i.e. if false is returned then readU8() would
154 // block.
155
156 public boolean bytesAvailable() { return end != ptr; }
157
158 // getbuf(), getptr(), getend() and setptr() are "dirty" methods which allow
159 // you to manipulate the buffer directly. This is useful for a stream which
160 // is a wrapper around an underlying stream.
161
162 public final byte[] getbuf() { return b; }
163 public final int getptr() { return ptr; }
164 public final int getend() { return end; }
165 public final void setptr(int p) { ptr = p; }
166
167 // overrun() is implemented by a derived class to cope with buffer overrun.
168 // It ensures there are at least itemSize bytes of buffer data. Returns
169 // the number of items in the buffer (up to a maximum of nItems). itemSize
170 // is supposed to be "small" (a few bytes).
171
172 abstract protected int overrun(int itemSize, int nItems) throws Exception;
173
174 protected InStream() {}
175 protected byte[] b;
176 protected int ptr;
177 protected int end;
178 }