File: DeflaterOutputStream.cs

package info (click to toggle)
mono 4.6.2.7+dfsg-1
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 778,148 kB
  • ctags: 914,052
  • sloc: cs: 5,779,509; xml: 2,773,713; ansic: 432,645; sh: 14,749; makefile: 12,361; perl: 2,488; python: 1,434; cpp: 849; asm: 531; sql: 95; sed: 16; php: 1
file content (471 lines) | stat: -rw-r--r-- 13,523 bytes parent folder | download | duplicates (2)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
// DeflaterOutputStream.cs
//
// Copyright (C) 2001 Mike Krueger
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 2001 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
// 
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module.  An independent module is a module which is not derived from
// or based on this library.  If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so.  If you do not wish to do so, delete this
// exception statement from your version.

using System;
using System.IO;
using ICSharpCode.SharpZipLib.Checksums;
using ICSharpCode.SharpZipLib.Zip.Compression;

namespace ICSharpCode.SharpZipLib.Zip.Compression.Streams 
{

	/// <summary>
	/// A special stream deflating or compressing the bytes that are
	/// written to it.  It uses a Deflater to perform actual deflating.<br/>
	/// Authors of the original java version : Tom Tromey, Jochen Hoenicke 
	/// </summary>
	public class DeflaterOutputStream : Stream
	{
		/// <summary>
		/// This buffer is used temporarily to retrieve the bytes from the
		/// deflater and write them to the underlying output stream.
		/// </summary>
		protected byte[] buf;
		
		/// <summary>
		/// The deflater which is used to deflate the stream.
		/// </summary>
		protected Deflater def;
		
		/// <summary>
		/// Base stream the deflater depends on.
		/// </summary>
		protected Stream baseOutputStream;

		bool isClosed = false;
		bool isStreamOwner = true;
		
		/// <summary>
		/// Get/set flag indicating ownership of underlying stream.
		/// When the flag is true <see cref="Close"></see> will close the underlying stream also.
		/// </summary>
		public bool IsStreamOwner
		{
			get { return isStreamOwner; }
			set { isStreamOwner = value; }
		}
		
		///	<summary>
		/// Allows client to determine if an entry can be patched after its added
		/// </summary>
		public bool CanPatchEntries {
			get { 
				return baseOutputStream.CanSeek; 
			}
		}
		
		/// <summary>
		/// Gets value indicating stream can be read from
		/// </summary>
		public override bool CanRead {
			get {
				return baseOutputStream.CanRead;
			}
		}
		
		/// <summary>
		/// Gets a value indicating if seeking is supported for this stream
		/// This property always returns false
		/// </summary>
		public override bool CanSeek {
			get {
				return false;
			}
		}
		
		/// <summary>
		/// Get value indicating if this stream supports writing
		/// </summary>
		public override bool CanWrite {
			get {
				return baseOutputStream.CanWrite;
			}
		}
		
		/// <summary>
		/// Get current length of stream
		/// </summary>
		public override long Length {
			get {
				return baseOutputStream.Length;
			}
		}
		
		/// <summary>
		/// The current position within the stream.
		/// Always throws a NotSupportedExceptionNotSupportedException
		/// </summary>
		/// <exception cref="NotSupportedException">Any attempt to set position</exception>
		public override long Position {
			get {
				return baseOutputStream.Position;
			}
			set {
				throw new NotSupportedException("DefalterOutputStream Position not supported");
			}
		}
		
		/// <summary>
		/// Sets the current position of this stream to the given value. Not supported by this class!
		/// </summary>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override long Seek(long offset, SeekOrigin origin)
		{
			throw new NotSupportedException("DeflaterOutputStream Seek not supported");
		}
		
		/// <summary>
		/// Sets the length of this stream to the given value. Not supported by this class!
		/// </summary>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override void SetLength(long val)
		{
			throw new NotSupportedException("DeflaterOutputStream SetLength not supported");
		}
		
		/// <summary>
		/// Read a byte from stream advancing position by one
		/// </summary>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override int ReadByte()
		{
			throw new NotSupportedException("DeflaterOutputStream ReadByte not supported");
		}
		
		/// <summary>
		/// Read a block of bytes from stream
		/// </summary>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override int Read(byte[] b, int off, int len)
		{
			throw new NotSupportedException("DeflaterOutputStream Read not supported");
		}
		
		/// <summary>
		/// Asynchronous reads are not supported a NotSupportedException is always thrown
		/// </summary>
		/// <param name="buffer"></param>
		/// <param name="offset"></param>
		/// <param name="count"></param>
		/// <param name="callback"></param>
		/// <param name="state"></param>
		/// <returns></returns>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
		{
			throw new NotSupportedException("DeflaterOutputStream BeginRead not currently supported");
		}
		
		/// <summary>
		/// Asynchronous writes arent supported, a NotSupportedException is always thrown
		/// </summary>
		/// <param name="buffer"></param>
		/// <param name="offset"></param>
		/// <param name="count"></param>
		/// <param name="callback"></param>
		/// <param name="state"></param>
		/// <returns></returns>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
		{
			throw new NotSupportedException("DeflaterOutputStream BeginWrite not currently supported");
		}
		
		/// <summary>
		/// Deflates everything in the input buffers.  This will call
		/// <code>def.deflate()</code> until all bytes from the input buffers
		/// are processed.
		/// </summary>
		protected void Deflate()
		{
			while (!def.IsNeedingInput) {
				int len = def.Deflate(buf, 0, buf.Length);
				
				if (len <= 0) {
					break;
				}
				
				if (this.keys != null) {
					this.EncryptBlock(buf, 0, len);
				}
				
				baseOutputStream.Write(buf, 0, len);
			}
			
			if (!def.IsNeedingInput) {
				throw new SharpZipBaseException("DeflaterOutputStream can't deflate all input?");
			}
		}
		
		/// <summary>
		/// Creates a new DeflaterOutputStream with a default Deflater and default buffer size.
		/// </summary>
		/// <param name="baseOutputStream">
		/// the output stream where deflated output should be written.
		/// </param>
		public DeflaterOutputStream(Stream baseOutputStream) : this(baseOutputStream, new Deflater(), 512)
		{
		}
		
		/// <summary>
		/// Creates a new DeflaterOutputStream with the given Deflater and
		/// default buffer size.
		/// </summary>
		/// <param name="baseOutputStream">
		/// the output stream where deflated output should be written.
		/// </param>
		/// <param name="defl">
		/// the underlying deflater.
		/// </param>
		public DeflaterOutputStream(Stream baseOutputStream, Deflater defl) : this(baseOutputStream, defl, 512)
		{
		}
		
		/// <summary>
		/// Creates a new DeflaterOutputStream with the given Deflater and
		/// buffer size.
		/// </summary>
		/// <param name="baseOutputStream">
		/// The output stream where deflated output is written.
		/// </param>
		/// <param name="deflater">
		/// The underlying deflater to use
		/// </param>
		/// <param name="bufsize">
		/// The buffer size to use when deflating
		/// </param>
		/// <exception cref="ArgumentOutOfRangeException">
		/// bufsize is less than or equal to zero.
		/// </exception>
		/// <exception cref="ArgumentException">
		/// baseOutputStream does not support writing
		/// </exception>
		/// <exception cref="ArgumentNullException">
		/// deflater instance is null
		/// </exception>
		public DeflaterOutputStream(Stream baseOutputStream, Deflater deflater, int bufsize)
		{
			if (baseOutputStream.CanWrite == false) {
				throw new ArgumentException("baseOutputStream", "must support writing");
			}

			if (deflater == null) {
				throw new ArgumentNullException("deflater");
			}
			
			if (bufsize <= 0) {
				throw new ArgumentOutOfRangeException("bufsize");
			}
			
			this.baseOutputStream = baseOutputStream;
			buf = new byte[bufsize];
			def = deflater;
		}
		
		/// <summary>
		/// Flushes the stream by calling flush() on the deflater and then
		/// on the underlying stream.  This ensures that all bytes are
		/// flushed.
		/// </summary>
		public override void Flush()
		{
			def.Flush();
			Deflate();
			baseOutputStream.Flush();
		}
		
		/// <summary>
		/// Finishes the stream by calling finish() on the deflater. 
		/// </summary>
		/// <exception cref="SharpZipBaseException">
		/// Not all input is deflated
		/// </exception>
		public virtual void Finish()
		{
			def.Finish();
			while (!def.IsFinished)  {
				int len = def.Deflate(buf, 0, buf.Length);
				if (len <= 0) {
					break;
				}
				
				if (this.keys != null) {
					this.EncryptBlock(buf, 0, len);
				}
				
				baseOutputStream.Write(buf, 0, len);
			}
			if (!def.IsFinished) {
				throw new SharpZipBaseException("Can't deflate all input?");
			}
			baseOutputStream.Flush();
			keys = null;
		}
		
		/// <summary>
		/// Calls finish() and closes the underlying
		/// stream when <see cref="IsStreamOwner"></see> is true.
		/// </summary>
		public override void Close()
		{
			if ( !isClosed ) {
				isClosed = true;
				Finish();
				if ( isStreamOwner ) {
					baseOutputStream.Close();
				}
			}
		}
		
		/// <summary>
		/// Writes a single byte to the compressed output stream.
		/// </summary>
		/// <param name="bval">
		/// The byte value.
		/// </param>
		public override void WriteByte(byte bval)
		{
			byte[] b = new byte[1];
			b[0] = bval;
			Write(b, 0, 1);
		}
		
		/// <summary>
		/// Writes bytes from an array to the compressed stream.
		/// </summary>
		/// <param name="buf">
		/// The byte array
		/// </param>
		/// <param name="off">
		/// The offset into the byte array where to start.
		/// </param>
		/// <param name="len">
		/// The number of bytes to write.
		/// </param>
		public override void Write(byte[] buf, int off, int len)
		{
			def.SetInput(buf, off, len);
			Deflate();
		}
		
		#region Encryption
		
		// TODO:  Refactor this code.  The presence of Zip specific code in this low level class is wrong
		string password = null;
		uint[] keys     = null;
		
		/// <summary>
		/// Get/set the password used for encryption.  When null no encryption is performed
		/// </summary>
		public string Password {
			get { 
				return password; 
			}
			set {
				if ( value != null && value.Length == 0 ) {
					password = null;
				} else {
					password = value; 
				}
			}
		}
		
		
		/// <summary>
		/// Encrypt a single byte 
		/// </summary>
		/// <returns>
		/// The encrypted value
		/// </returns>
		protected byte EncryptByte()
		{
			uint temp = ((keys[2] & 0xFFFF) | 2);
			return (byte)((temp * (temp ^ 1)) >> 8);
		}
		
		
		/// <summary>
		/// Encrypt a block of data
		/// </summary>
		/// <param name="buffer">
		/// Data to encrypt.  NOTE the original contents of the buffer are lost
		/// </param>
		/// <param name="offset">
		/// Offset of first byte in buffer to encrypt
		/// </param>
		/// <param name="length">
		/// Number of bytes in buffer to encrypt
		/// </param>
		protected void EncryptBlock(byte[] buffer, int offset, int length)
		{
			// TODO: refactor to use crypto transform
			for (int i = offset; i < offset + length; ++i) {
				byte oldbyte = buffer[i];
				buffer[i] ^= EncryptByte();
				UpdateKeys(oldbyte);
			}
		}
		
		/// <summary>
		/// Initializes encryption keys based on given password
		/// </summary>
		protected void InitializePassword(string password) {
			keys = new uint[] {
				0x12345678,
				0x23456789,
				0x34567890
			};
			
			for (int i = 0; i < password.Length; ++i) {
				UpdateKeys((byte)password[i]);
			}
		}

		/// <summary>
		/// Update encryption keys 
		/// </summary>		
		protected void UpdateKeys(byte ch)
		{
			keys[0] = Crc32.ComputeCrc32(keys[0], ch);
			keys[1] = keys[1] + (byte)keys[0];
			keys[1] = keys[1] * 134775813 + 1;
			keys[2] = Crc32.ComputeCrc32(keys[2], (byte)(keys[1] >> 24));
		}
		#endregion
	}
}