mcs/class/ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib/Tar/TarBuffer.cs

   1 // TarBuffer.cs
   2 // Copyright (C) 2001 Mike Krueger
   3 //
   4 // This program is free software; you can redistribute it and/or
   5 // modify it under the terms of the GNU General Public License
   6 // as published by the Free Software Foundation; either version 2
   7 // of the License, or (at your option) any later version.
   8 //
   9 // This program 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 program; if not, write to the Free Software
  16 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  17 //
  18 // Linking this library statically or dynamically with other modules is
  19 // making a combined work based on this library.  Thus, the terms and
  20 // conditions of the GNU General Public License cover the whole
  21 // combination.
  22 //
  23 // As a special exception, the copyright holders of this library give you
  24 // permission to link this library with independent modules to produce an
  25 // executable, regardless of the license terms of these independent
  26 // modules, and to copy and distribute the resulting executable under
  27 // terms of your choice, provided that you also meet, for each linked
  28 // independent module, the terms and conditions of the license of that
  29 // module.  An independent module is a module which is not derived from
  30 // or based on this library.  If you modify this library, you may extend
  31 // this exception to your version of the library, but you are not
  32 // obligated to do so.  If you do not wish to do so, delete this
  33 // exception statement from your version.
  34
  35 using System;
  36 using System.IO;
  37 using System.Text;
  38
  39 namespace ICSharpCode.SharpZipLib.Tar
  40 {
  41
  42         /// <summary>
  43         /// The TarBuffer class implements the tar archive concept
  44         /// of a buffered input stream. This concept goes back to the
  45         /// days of blocked tape drives and special io devices. In the
  46         /// C# universe, the only real function that this class
  47         /// performs is to ensure that files have the correct "record"
  48         /// size, or other tars will complain.
  49         /// <p>
  50         /// You should never have a need to access this class directly.
  51         /// TarBuffers are created by Tar IO Streams.
  52         /// </p>
  53         /// </summary>
  54         public class TarBuffer
  55         {
  56
  57 /* A quote from GNU tar man file on blocking and records
  58    A `tar' archive file contains a series of blocks.  Each block
  59 contains `BLOCKSIZE' bytes.  Although this format may be thought of as
  60 being on magnetic tape, other media are often used.
  61
  62    Each file archived is represented by a header block which describes
  63 the file, followed by zero or more blocks which give the contents of
  64 the file.  At the end of the archive file there may be a block filled
  65 with binary zeros as an end-of-file marker.  A reasonable system should
  66 write a block of zeros at the end, but must not assume that such a
  67 block exists when reading an archive.
  68
  69    The blocks may be "blocked" for physical I/O operations.  Each
  70 record of N blocks (where N is set by the `--blocking-factor=512-SIZE'
  71 (`-b 512-SIZE') option to `tar') is written with a single `write ()'
  72 operation.  On magnetic tapes, the result of such a write is a single
  73 record.  When writing an archive, the last record of blocks should be
  74 written at the full size, with blocks after the zero block containing
  75 all zeros.  When reading an archive, a reasonable system should
  76 properly handle an archive whose last record is shorter than the rest,
  77 or which contains garbage records after a zero block.
  78 */
  79
  80 //      public static readonly int DEFAULT_RCDSIZE = 512;
  81 //      public const int DEFAULT_BLOCKFACTOR = 20;
  82 //           public static readonly int DEFAULT_BLKSIZE = DEFAULT_RCDSIZE * DEFAULT_BLOCKFACTOR;
  83
  84       public static readonly int BlockSize = 512;
  85       public static readonly int DefaultBlockFactor = 20;
  86       public static readonly int DefaultRecordSize = BlockSize * DefaultBlockFactor;
  87
  88                 Stream inputStream;
  89                 Stream outputStream;
  90
  91                 byte[] recordBuffer;
  92                 int    currentBlockIndex;
  93                 int    currentRecordIndex;
  94
  95                 int    recordSize = DefaultRecordSize;
  96       public int RecordSize
  97       {
  98          get { return recordSize; }
  99       }
 100
 101       int    blockFactor = DefaultBlockFactor;
 102
 103       public int BlockFactor
 104       {
 105          get { return blockFactor; }
 106       }
 107
 108                 bool   debug = false;
 109
 110       /// <summary>
 111       /// Set the debugging flag for the buffer.
 112       /// </summary>
 113       public void SetDebug(bool debug)
 114       {
 115          this.debug = debug;
 116       }
 117
 118
 119                 protected TarBuffer()
 120                 {
 121                 }
 122
 123                 public static TarBuffer CreateInputTarBuffer(Stream inputStream)
 124                 {
 125                         return CreateInputTarBuffer(inputStream, TarBuffer.DefaultBlockFactor);
 126                 }
 127
 128                 public static TarBuffer CreateInputTarBuffer(Stream inputStream, int blockFactor)
 129                 {
 130                         TarBuffer tarBuffer = new TarBuffer();
 131                         tarBuffer.inputStream  = inputStream;
 132                         tarBuffer.outputStream = null;
 133                         tarBuffer.Initialize(blockFactor);
 134
 135                         return tarBuffer;
 136                 }
 137
 138                 public static TarBuffer CreateOutputTarBuffer(Stream outputStream)
 139                 {
 140                         return CreateOutputTarBuffer(outputStream, TarBuffer.DefaultBlockFactor);
 141                 }
 142
 143                 public static TarBuffer CreateOutputTarBuffer(Stream outputStream, int blockFactor)
 144                 {
 145                         TarBuffer tarBuffer = new TarBuffer();
 146                         tarBuffer.inputStream  = null;
 147                         tarBuffer.outputStream = outputStream;
 148                         tarBuffer.Initialize(blockFactor);
 149
 150                         return tarBuffer;
 151                 }
 152
 153                 /// <summary>
 154                 /// Initialization common to all constructors.
 155                 /// </summary>
 156                 void Initialize(int blockFactor)
 157                 {
 158                         this.debug        = false;
 159          this.blockFactor  = blockFactor;
 160          this.recordSize   = blockFactor * BlockSize;
 161
 162                         this.recordBuffer  = new byte[RecordSize];
 163
 164                         if (inputStream != null)
 165                         {
 166                                 this.currentRecordIndex = -1;
 167                                 this.currentBlockIndex = BlockFactor;
 168                         }
 169                         else
 170                         {
 171             this.currentRecordIndex = 0;
 172             this.currentBlockIndex = 0;
 173                         }
 174                 }
 175
 176                 /// <summary>
 177                 /// Get the TAR Buffer's block factor
 178                 /// </summary>
 179                 public int GetBlockFactor()
 180                 {
 181                         return this.blockFactor;
 182                 }
 183
 184                 /// <summary>
 185                 /// Get the TAR Buffer's record size.
 186                 /// </summary>
 187                 public int GetRecordSize()
 188                 {
 189                         return this.recordSize;
 190                 }
 191
 192                 /// <summary>
 193                 /// Determine if an archive block indicates End of Archive. End of
 194                 /// archive is indicated by a block that consists entirely of null bytes.
 195                 /// All remaining blocks for the record should also be null's
 196                 /// However some older tars only do a couple of null blocks (Old GNU tar for one)
 197                 /// and also partial records
 198                 /// </summary>
 199                 /// <param name = "block">
 200                 /// The block data to check.
 201                 /// </param>
 202                 public bool IsEOFBlock(byte[] block)
 203                 {
 204                         for (int i = 0, sz = BlockSize; i < sz; ++i)
 205                         {
 206                                 if (block[i] != 0)
 207                                 {
 208                                         return false;
 209                                 }
 210                         }
 211
 212                         return true;
 213                 }
 214
 215                 /// <summary>
 216                 /// Skip over a block on the input stream.
 217                 /// </summary>
 218                 public void SkipBlock()
 219                 {
 220                         if (this.debug)
 221                         {
 222                                 //Console.WriteLine.WriteLine("SkipBlock: recIdx = " + this.currentRecordIndex + " blkIdx = " + this.currentBlockIndex);
 223                         }
 224
 225                         if (this.inputStream == null)
 226                         {
 227                                 throw new System.IO.IOException("no input stream defined");
 228                         }
 229
 230                         if (this.currentBlockIndex >= this.BlockFactor)
 231                         {
 232                                 if (!this.ReadRecord())
 233                                 {
 234                                         return; // UNDONE
 235                                 }
 236                         }
 237
 238                         this.currentBlockIndex++;
 239                 }
 240
 241                 /// <summary>
 242                 /// Read a block from the input stream and return the data.
 243                 /// </summary>
 244                 /// <returns>
 245                 /// The block data.
 246                 /// </returns>
 247                 public byte[] ReadBlock()
 248                 {
 249                         if (this.debug)
 250                         {
 251                                 //Console.WriteLine.WriteLine( "ReadBlock: blockIndex = " + this.currentBlockIndex + " recordIndex = " + this.currentRecordIndex );
 252                         }
 253
 254                         if (this.inputStream == null)
 255                         {
 256                                 throw new ApplicationException("TarBuffer.ReadBlock - no input stream defined");
 257                         }
 258
 259                         if (this.currentBlockIndex >= this.BlockFactor)
 260                         {
 261                                 if (!this.ReadRecord())
 262                                 {
 263                                         return null;
 264                                 }
 265                         }
 266
 267                         byte[] result = new byte[BlockSize];
 268
 269                         Array.Copy(this.recordBuffer, (this.currentBlockIndex * BlockSize), result, 0, BlockSize );
 270                         this.currentBlockIndex++;
 271                         return result;
 272                 }
 273
 274                 /// <returns>
 275                 /// false if End-Of-File, else true
 276                 /// </returns>
 277                 bool ReadRecord()
 278                 {
 279                         if (this.debug)
 280                         {
 281                                 //Console.WriteLine.WriteLine("ReadRecord: recordIndex = " + this.currentRecordIndex);
 282                         }
 283
 284                         if (this.inputStream == null)
 285                         {
 286                                 throw new System.IO.IOException("no input stream stream defined");
 287                         }
 288
 289                         this.currentBlockIndex = 0;
 290
 291                         int offset = 0;
 292                         int bytesNeeded = RecordSize;
 293
 294                         while (bytesNeeded > 0)
 295                         {
 296                                 long numBytes = this.inputStream.Read(this.recordBuffer, offset, bytesNeeded);
 297
 298                                 //
 299                                 // NOTE
 300                                 // We have found EOF, and the record is not full!
 301                                 //
 302                                 // This is a broken archive. It does not follow the standard
 303                                 // blocking algorithm. However, because we are generous, and
 304                                 // it requires little effort, we will simply ignore the error
 305                                 // and continue as if the entire record were read. This does
 306                                 // not appear to break anything upstream. We used to return
 307                                 // false in this case.
 308                                 //
 309                                 // Thanks to 'Yohann.Roussel@alcatel.fr' for this fix.
 310                                 //
 311                                 if (numBytes <= 0)
 312                                 {
 313                                         break;
 314                                 }
 315
 316                                 offset      += (int)numBytes;
 317                                 bytesNeeded -= (int)numBytes;
 318                                 if (numBytes != RecordSize)
 319                                 {
 320                                         if (this.debug)
 321                                         {
 322                                                 //Console.WriteLine.WriteLine("ReadRecord: INCOMPLETE READ " + numBytes + " of " + this.blockSize + " bytes read.");
 323                                         }
 324                                 }
 325                         }
 326
 327                         this.currentRecordIndex++;
 328                         return true;
 329                 }
 330
 331                 /// <summary>
 332                 /// Get the current block number, within the current record, zero based.
 333                 /// </summary>
 334                 /// <returns>
 335                 /// The current zero based block number.
 336                 /// </returns>
 337                 public int GetCurrentBlockNum()
 338                 {
 339                         return this.currentBlockIndex;
 340                 }
 341
 342                 /// <summary>
 343                 /// Get the current record number
 344                 /// Absolute block number in file = (currentRecordNum * block factor) + currentBlockNum.
 345                 /// </summary>
 346                 /// <returns>
 347                 /// The current zero based record number.
 348                 /// </returns>
 349                 public int GetCurrentRecordNum()
 350                 {
 351                         return this.currentRecordIndex;
 352                 }
 353
 354                 /// <summary>
 355                 /// Write an archive block to the archive.
 356                 /// </summary>
 357                 /// <param name="block">
 358                 /// The data to write to the archive.
 359                 /// </param>
 360                 ///
 361                 public void WriteBlock(byte[] block)
 362                 {
 363                         if (this.debug)
 364                         {
 365                                 //Console.WriteLine.WriteLine("WriteRecord: recIdx = " + this.currentRecordIndex + " blkIdx = " + this.currentBlockIndex );
 366                         }
 367
 368                         if (this.outputStream == null)
 369                         {
 370                                 throw new ApplicationException("TarBuffer.WriteBlock - no output stream defined");
 371                         }
 372
 373                         if (block.Length != BlockSize)
 374                         {
 375                                 throw new ApplicationException("TarBuffer.WriteBlock - block to write has length '" + block.Length + "' which is not the block size of '" + BlockSize + "'" );
 376                         }
 377
 378                         if (this.currentBlockIndex >= BlockFactor)
 379                         {
 380                                 this.WriteRecord();
 381                         }
 382
 383                         Array.Copy(block, 0, this.recordBuffer, (this.currentBlockIndex * BlockSize), BlockSize);
 384                         this.currentBlockIndex++;
 385                 }
 386
 387                 /// <summary>
 388                 /// Write an archive record to the archive, where the record may be
 389                 /// inside of a larger array buffer. The buffer must be "offset plus
 390                 /// record size" long.
 391                 /// </summary>
 392                 /// <param name="buf">
 393                 /// The buffer containing the record data to write.
 394                 /// </param>
 395                 /// <param name="offset">
 396                 /// The offset of the record data within buf.
 397                 /// </param>
 398                 public void WriteBlock(byte[] buf, int offset)
 399                 {
 400                         if (this.debug)
 401                         {
 402                                 //Console.WriteLine.WriteLine("WriteBlock: recIdx = " + this.currentRecordIndex + " blkIdx = " + this.currentBlockIndex );
 403                         }
 404
 405                         if (this.outputStream == null)
 406                         {
 407                                 throw new ApplicationException("TarBuffer.WriteBlock - no output stream stream defined");
 408                         }
 409
 410                         if ((offset + BlockSize) > buf.Length)
 411                         {
 412                                 throw new ApplicationException("TarBuffer.WriteBlock - record has length '" + buf.Length + "' with offset '" + offset + "' which is less than the record size of '" + this.recordSize + "'" );
 413                         }
 414
 415                         if (this.currentBlockIndex >= this.BlockFactor)
 416                         {
 417                                 this.WriteRecord();
 418                         }
 419
 420                         Array.Copy(buf, offset, this.recordBuffer, (this.currentBlockIndex * BlockSize), BlockSize);
 421
 422                         this.currentBlockIndex++;
 423                 }
 424
 425                 /// <summary>
 426                 /// Write a TarBuffer record to the archive.
 427                 /// </summary>
 428                 void WriteRecord()
 429                 {
 430                         if (this.debug)
 431                         {
 432                                 //Console.WriteLine.WriteLine("Writerecord: record index = " + this.currentRecordIndex);
 433                         }
 434
 435                         if (this.outputStream == null)
 436                         {
 437                                 throw new ApplicationException("TarBuffer.WriteRecord no output stream defined");
 438                         }
 439
 440                         this.outputStream.Write(this.recordBuffer, 0, RecordSize);
 441                         this.outputStream.Flush();
 442
 443          this.currentBlockIndex = 0;
 444          this.currentRecordIndex++;
 445                 }
 446
 447                 /// <summary>
 448                 /// Flush the current data block if it has any data in it.
 449                 /// </summary>
 450                 void Flush()
 451                 {
 452                         if (this.debug)
 453                         {
 454                                 //Console.WriteLine.WriteLine("TarBuffer.FlushBlock() called.");
 455                         }
 456
 457                         if (this.outputStream == null)
 458                         {
 459                                 throw new ApplicationException("TarBuffer.Flush no output stream defined");
 460                         }
 461
 462                         if (this.currentBlockIndex > 0)
 463                         {
 464                                 this.WriteRecord();
 465                         }
 466                         outputStream.Flush();
 467                 }
 468
 469                 /// <summary>
 470                 /// Close the TarBuffer. If this is an output buffer, also flush the
 471                 /// current block before closing.
 472                 /// </summary>
 473                 public void Close()
 474                 {
 475                         if (this.debug)
 476                         {
 477                                 //Console.WriteLine.WriteLine("TarBuffer.Close().");
 478                         }
 479
 480                         if (outputStream != null)
 481                         {
 482                                 Flush();
 483
 484                                 outputStream.Close();
 485                                 outputStream = null;
 486                         }
 487                         else if (inputStream != null)
 488                         {
 489                                 inputStream.Close();
 490                                 inputStream = null;
 491                         }
 492                 }
 493         }
 494 }
 495
 496 /* The original Java file had this header:
 497         *
 498         ** Authored by Timothy Gerard Endres
 499         ** <mailto:time@gjt.org>  <http://www.trustice.com>
 500         **
 501         ** This work has been placed into the public domain.
 502         ** You may use this work in any way and for any purpose you wish.
 503         **
 504         ** THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY OF ANY KIND,
 505         ** NOT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY. THE AUTHOR
 506         ** OF THIS SOFTWARE, ASSUMES _NO_ RESPONSIBILITY FOR ANY
 507         ** CONSEQUENCE RESULTING FROM THE USE, MODIFICATION, OR
 508         ** REDISTRIBUTION OF THIS SOFTWARE.
 509         **
 510         */