mcs/class/System.Web/System.Web/HttpResponseStream.cs

   1 //
   2 // System.Web.HttpResponseStream.cs
   3 //
   4 //
   5 // Author:
   6 //      Miguel de Icaza (miguel@novell.com)
   7 //      Ben Maurer (bmaurer@ximian.com)
   8 //
   9 //
  10 // Copyright (C) 2005 Novell, Inc (http://www.novell.com)
  11 //
  12 // Permission is hereby granted, free of charge, to any person obtaining
  13 // a copy of this software and associated documentation files (the
  14 // "Software"), to deal in the Software without restriction, including
  15 // without limitation the rights to use, copy, modify, merge, publish,
  16 // distribute, sublicense, and/or sell copies of the Software, and to
  17 // permit persons to whom the Software is furnished to do so, subject to
  18 // the following conditions:
  19 //
  20 // The above copyright notice and this permission notice shall be
  21 // included in all copies or substantial portions of the Software.
  22 //
  23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  27 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  28 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  29 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  30 //
  31
  32 using System;
  33 using System.IO;
  34 using System.Text;
  35 using System.Globalization;
  36 using System.Runtime.InteropServices;
  37
  38 namespace System.Web {
  39
  40         //
  41         // HttpResponseStream implements the "OutputStream" from HttpResponse
  42         //
  43         // The MS implementation is broken in that it does not hook up this
  44         // to HttpResponse, so calling "Flush" on Response.OutputStream does not
  45         // flush the contents and produce the headers.
  46         //
  47         // You must call HttpResponse.Flush which does the actual header generation
  48         // and actual data flushing
  49         //
  50         internal class HttpResponseStream : Stream {
  51                 Bucket first_bucket;
  52                 Bucket cur_bucket;
  53                 HttpResponse response;
  54                 internal long total;
  55                 Stream filter;
  56                 byte [] chunk_buffer = new byte [24];
  57
  58                 public HttpResponseStream (HttpResponse response)
  59                 {
  60                         this.response = response;
  61                 }
  62
  63                 internal bool HaveFilter {
  64                         get { return filter != null; }
  65                 }
  66
  67                 public Stream Filter {
  68                         get {
  69                                 if (filter == null)
  70                                         filter = new OutputFilterStream (this);
  71                                 return filter;
  72                         }
  73                         set {
  74                                 filter = value;
  75                         }
  76                 }
  77 #if TARGET_JVM
  78
  79                 class BlockManager {
  80                         const int PreferredLength = 16 * 1024;
  81                         static readonly byte[] EmptyBuffer = new byte[0];
  82
  83                         byte[] buffer = EmptyBuffer;
  84                         int position;
  85
  86                         public BlockManager () {
  87                         }
  88
  89                         public int Position {
  90                                 get { return position; }
  91                         }
  92
  93                         void EnsureCapacity (int capacity) {
  94                                 if (buffer.Length >= capacity)
  95                                         return;
  96
  97                                 capacity += PreferredLength;
  98                                 capacity = (capacity / PreferredLength) * PreferredLength;
  99                                 byte[] temp = new byte[capacity];
 100                                 Array.Copy(buffer, 0, temp, 0, buffer.Length);
 101                                 buffer = temp;
 102                         }
 103
 104                         public void Write (byte [] buffer, int offset, int count) {
 105                                 if (count == 0)
 106                                         return;
 107
 108                                 EnsureCapacity (position + count);
 109                                 Array.Copy(buffer, offset, this.buffer, position, count);
 110                                 position += count;
 111                         }
 112
 113                         public void Send (HttpWorkerRequest wr, int start, int end) {
 114                                 int length = end - start;
 115                                 if (length <= 0)
 116                                         return;
 117
 118                                 if (length > buffer.Length - start)
 119                                         length = buffer.Length - start;
 120
 121                                 if (start > 0) {
 122                                         byte[] temp = new byte[length];
 123                                         Array.Copy(buffer, start, temp, 0, length);
 124                                         buffer = temp;
 125                                 }
 126                                 wr.SendResponseFromMemory(buffer, length);
 127                         }
 128
 129                         public void Send (Stream stream, int start, int end) {
 130                                 int length = end - start;
 131                                 if (length <= 0)
 132                                         return;
 133
 134                                 if (length > buffer.Length - start)
 135                                         length = buffer.Length - start;
 136
 137                                 stream.Write(buffer, start, length);
 138                         }
 139
 140                         public void Dispose () {
 141                                 buffer = null;
 142                         }
 143                 }
 144
 145 #else // TARGET_JVM
 146                 unsafe sealed class BlockManager {
 147                         const int PreferredLength = 128 * 1024;
 148                         byte *data;
 149                         int position;
 150                         int block_size;
 151
 152                         public BlockManager ()
 153                         {
 154                         }
 155
 156                         public int Position {
 157                                 get { return position; }
 158                         }
 159
 160                         void EnsureCapacity (int capacity)
 161                         {
 162                                 if (block_size >= capacity)
 163                                         return;
 164
 165                                 capacity += PreferredLength;
 166                                 capacity = (capacity / PreferredLength) * PreferredLength;
 167
 168                                 data = data == null
 169                                         ? (byte *) Marshal.AllocHGlobal (capacity)
 170                                         : (byte *) Marshal.ReAllocHGlobal ((IntPtr) data, (IntPtr) capacity);
 171                                 block_size = capacity;
 172                         }
 173
 174                         public void Write (byte [] buffer, int offset, int count)
 175                         {
 176                                 if (count == 0)
 177                                         return;
 178
 179                                 EnsureCapacity (position + count);
 180                                 Marshal.Copy (buffer, offset, (IntPtr) (data + position), count);
 181                                 position += count;
 182                         }
 183
 184                         public void Write (IntPtr ptr, int count)
 185                         {
 186                                 if (count == 0)
 187                                         return;
 188
 189                                 EnsureCapacity (position + count);
 190                                 byte *src = (byte *) ptr.ToPointer ();
 191                                 memcpy (data + position, src, count);
 192                                 position += count;
 193                         }
 194
 195                         public void Send (HttpWorkerRequest wr, int start, int end)
 196                         {
 197                                 if (end - start <= 0)
 198                                         return;
 199
 200                                 wr.SendResponseFromMemory ((IntPtr) (data + start), end - start);
 201                         }
 202
 203                         public void Send (Stream stream, int start, int end)
 204                         {
 205                                 int len = end - start;
 206                                 if (len <= 0)
 207                                         return;
 208
 209                                 byte [] buffer = new byte [Math.Min (len, 32 * 1024)];
 210                                 int size = buffer.Length;
 211                                 while (len > 0) {
 212                                         Marshal.Copy ((IntPtr) (data + start), buffer, 0, size);
 213                                         stream.Write (buffer, 0, size);
 214                                         start += size;
 215                                         len -= size;
 216                                         if (len > 0 && len < size)
 217                                                 size = len;
 218                                 }
 219                         }
 220
 221                         public void Dispose ()
 222                         {
 223                                 if ((IntPtr) data != IntPtr.Zero) {
 224                                         Marshal.FreeHGlobal ((IntPtr) data);
 225                                         data = (byte *) IntPtr.Zero;
 226                                 }
 227                         }
 228                 }
 229
 230 #endif
 231                 abstract class Bucket {
 232                         public Bucket Next;
 233
 234                         public virtual void Dispose ()
 235                         {
 236                         }
 237
 238                         public abstract void Send (HttpWorkerRequest wr);
 239                         public abstract void Send (Stream stream);
 240                         public abstract int Length { get; }
 241                 }
 242
 243 #if !TARGET_JVM
 244                 unsafe
 245 #endif
 246                 class ByteBucket : Bucket {
 247                         int start;
 248                         int length;
 249                         public BlockManager blocks;
 250                         public bool Expandable = true;
 251
 252                         public ByteBucket () : this (null)
 253                         {
 254                         }
 255
 256                         public ByteBucket (BlockManager blocks)
 257                         {
 258                                 if (blocks == null)
 259                                         blocks = new BlockManager ();
 260
 261                                 this.blocks = blocks;
 262                                 start = blocks.Position;
 263                         }
 264
 265                         public override int Length {
 266                                 get { return length; }
 267                         }
 268
 269                         public int Write (byte [] buf, int offset, int count)
 270                         {
 271                                 if (Expandable == false)
 272                                         throw new Exception ("This should not happen.");
 273
 274                                 blocks.Write (buf, offset, count);
 275                                 length += count;
 276                                 return count;
 277                         }
 278
 279                         public int Write (IntPtr ptr, int count)
 280                         {
 281                                 if (Expandable == false)
 282                                         throw new Exception ("This should not happen.");
 283
 284                                 blocks.Write (ptr, count);
 285                                 length += count;
 286                                 return count;
 287                         }
 288
 289                         public override void Dispose ()
 290                         {
 291                                 blocks.Dispose ();
 292                         }
 293
 294                         public override void Send (HttpWorkerRequest wr)
 295                         {
 296                                 if (length == 0)
 297                                         return;
 298
 299                                 blocks.Send (wr, start, length);
 300                         }
 301
 302                         public override void Send (Stream stream)
 303                         {
 304                                 if (length == 0)
 305                                         return;
 306
 307                                 blocks.Send (stream, start, length);
 308                         }
 309                 }
 310
 311                 class BufferedFileBucket : Bucket {
 312                         string file;
 313                         long offset;
 314                         long length;
 315
 316                         public BufferedFileBucket (string f, long off, long len)
 317                         {
 318                                 file = f;
 319                                 offset = off;
 320                                 length = len;
 321                         }
 322
 323                         public override int Length {
 324                                 get { return (int) length; }
 325                         }
 326
 327                         public override void Send (HttpWorkerRequest wr)
 328                         {
 329                                 wr.SendResponseFromFile (file, offset, length);
 330                         }
 331
 332                         public override void Send (Stream stream)
 333                         {
 334                                 using (FileStream fs = File.OpenRead (file)) {
 335                                         byte [] buffer = new byte [Math.Min (fs.Length, 32*1024)];
 336
 337                                         long remain = fs.Length;
 338                                         int n;
 339                                         while (remain > 0 && (n = fs.Read (buffer, 0, (int) Math.Min (remain, 32*1024))) != 0){
 340                                                 remain -= n;
 341                                                 stream.Write (buffer, 0, n);
 342                                         }
 343                                 }
 344                         }
 345
 346                         public override string ToString ()
 347                         {
 348                                 return "file " + file + " " + length.ToString () + " bytes from position " + offset.ToString ();
 349                         }
 350                 }
 351
 352                 void AppendBucket (Bucket b)
 353                 {
 354                         if (first_bucket == null) {
 355                                 cur_bucket = first_bucket = b;
 356                                 return;
 357                         }
 358
 359                         cur_bucket.Next = b;
 360                         cur_bucket = b;
 361                 }
 362
 363                 //
 364                 // Nothing happens here, broken by requirement.
 365                 // See note at the start
 366                 //
 367                 public override void Flush ()
 368                 {
 369                 }
 370
 371                 void SendChunkSize (long l, bool last)
 372                 {
 373                         if (l == 0 && !last)
 374                                 return;
 375
 376                         int i = 0;
 377                         if (l >= 0) {
 378                                 string s = l.ToString ("x");
 379                                 for (; i < s.Length; i++)
 380                                         chunk_buffer [i] = (byte) s [i];
 381                         }
 382
 383                         chunk_buffer [i++] = 13;
 384                         chunk_buffer [i++] = 10;
 385                         if (last) {
 386                                 chunk_buffer [i++] = 13;
 387                                 chunk_buffer [i++] = 10;
 388                         }
 389
 390                         response.WorkerRequest.SendResponseFromMemory (chunk_buffer, i);
 391                 }
 392
 393                 internal void Flush (HttpWorkerRequest wr, bool final_flush)
 394                 {
 395                         if (total == 0 && !final_flush)
 396                                 return;
 397
 398                         if (response.use_chunked)
 399                                 SendChunkSize (total, false);
 400
 401                         for (Bucket b = first_bucket; b != null; b = b.Next) {
 402                                 b.Send (wr);
 403                         }
 404
 405                         if (response.use_chunked) {
 406                                 SendChunkSize (-1, false);
 407                                 if (final_flush)
 408                                         SendChunkSize (0, true);
 409                         }
 410
 411                         wr.FlushResponse (final_flush);
 412
 413                         Clear ();
 414                 }
 415
 416                 internal int GetTotalLength ()
 417                 {
 418                         int size = 0;
 419                         for (Bucket b = first_bucket; b != null; b = b.Next)
 420                                 size += b.Length;
 421
 422                         return size;
 423                 }
 424
 425                 internal MemoryStream GetData ()
 426                 {
 427                         MemoryStream stream = new MemoryStream ();
 428                         for (Bucket b = first_bucket; b != null; b = b.Next)
 429                                 b.Send (stream);
 430                         return stream;
 431                 }
 432
 433                 public void WriteFile (string f, long offset, long length)
 434                 {
 435                         if (length == 0)
 436                                 return;
 437
 438                         ByteBucket bb = cur_bucket as ByteBucket;
 439
 440                         if (bb != null) {
 441                                 bb.Expandable = false;
 442                                 bb = new ByteBucket (bb.blocks);
 443                         }
 444
 445                         total += length;
 446
 447                         AppendBucket (new BufferedFileBucket (f, offset, length));
 448                         if (bb != null)
 449                                 AppendBucket (bb);
 450                         // Flush () is called from HttpResponse if needed (WriteFile/TransmitFile)
 451                 }
 452
 453                 bool filtering;
 454                 internal void ApplyFilter (bool close)
 455                 {
 456                         if (filter == null)
 457                                 return;
 458
 459                         filtering = true;
 460                         Bucket one = first_bucket;
 461                         first_bucket = null; // This will recreate new buckets for the filtered content
 462                         cur_bucket = null;
 463                         total = 0;
 464                         for (Bucket b = one; b != null; b = b.Next)
 465                                 b.Send (filter);
 466
 467                         for (Bucket b = one; b != null; b = b.Next)
 468                                 b.Dispose ();
 469
 470                         if (close) {
 471                                 filter.Flush ();
 472                                 filter.Close ();
 473                                 filter = null;
 474                         } else {
 475                                 filter.Flush ();
 476                         }
 477                         filtering = false;
 478                 }
 479
 480                 public void WritePtr (IntPtr ptr, int length)
 481                 {
 482                         if (length == 0)
 483                                 return;
 484
 485                         bool buffering = response.BufferOutput;
 486
 487                         if (buffering) {
 488                                 // It does not matter whether we're in ApplyFilter or not
 489                                 AppendBuffer (ptr, length);
 490                         } else if (filter == null || filtering) {
 491                                 response.WriteHeaders (false);
 492                                 HttpWorkerRequest wr = response.WorkerRequest;
 493                                 // Direct write because not buffering
 494                                 wr.SendResponseFromMemory (ptr, length);
 495                                 wr.FlushResponse (false);
 496                         } else {
 497                                 // Write to the filter, which will call us back, and then Flush
 498                                 filtering = true;
 499                                 try {
 500                                         byte [] bytes = new byte [length];
 501                                         Marshal.Copy (ptr, bytes, 0, length);
 502                                         filter.Write (bytes, 0, length);
 503                                         bytes = null;
 504                                 } finally {
 505                                         filtering = false;
 506                                 }
 507                                 Flush (response.WorkerRequest, false);
 508                         }
 509
 510                 }
 511
 512                 public override void Write (byte [] buffer, int offset, int count)
 513                 {
 514                         bool buffering = response.BufferOutput;
 515
 516                         if (buffering) {
 517                                 // It does not matter whether we're in ApplyFilter or not
 518                                 AppendBuffer (buffer, offset, count);
 519                         } else if (filter == null || filtering) {
 520                                 response.WriteHeaders (false);
 521                                 HttpWorkerRequest wr = response.WorkerRequest;
 522                                 // Direct write because not buffering
 523                                 if (offset == 0) {
 524                                         wr.SendResponseFromMemory (buffer, count);
 525                                 } else {
 526                                         UnsafeWrite (wr, buffer, offset, count);
 527                                 }
 528                                 wr.FlushResponse (false);
 529                         } else {
 530                                 // Write to the filter, which will call us back, and then Flush
 531                                 filtering = true;
 532                                 try {
 533                                         filter.Write (buffer, offset, count);
 534                                 } finally {
 535                                         filtering = false;
 536                                 }
 537                                 Flush (response.WorkerRequest, false);
 538                         }
 539                 }
 540
 541 #if TARGET_JVM
 542                 void UnsafeWrite (HttpWorkerRequest wr, byte [] buffer, int offset, int count)
 543                 {
 544                         if (count <= 0)
 545                                 return;
 546
 547                         byte[] copy = new byte[count];
 548                         Array.Copy(buffer, offset, copy, 0, count);
 549                         wr.SendResponseFromMemory (copy, count);
 550                 }
 551 #else
 552                 unsafe void UnsafeWrite (HttpWorkerRequest wr, byte [] buffer, int offset, int count)
 553                 {
 554                         fixed (byte *ptr = buffer) {
 555                                 wr.SendResponseFromMemory ((IntPtr) (ptr + offset), count);
 556                         }
 557                 }
 558 #endif
 559                 void AppendBuffer (byte [] buffer, int offset, int count)
 560                 {
 561                         if (!(cur_bucket is ByteBucket))
 562                                 AppendBucket (new ByteBucket ());
 563
 564                         total += count;
 565                         ((ByteBucket) cur_bucket).Write (buffer, offset, count);
 566                 }
 567
 568                 void AppendBuffer (IntPtr ptr, int count)
 569                 {
 570                         if (!(cur_bucket is ByteBucket))
 571                                 AppendBucket (new ByteBucket ());
 572
 573                         total += count;
 574                         ((ByteBucket) cur_bucket).Write (ptr, count);
 575                 }
 576
 577                 //
 578                 // This should not flush/close or anything else, its called
 579                 // just to free any memory we might have allocated (when we later
 580                 // implement something with unmanaged memory).
 581                 //
 582                 internal void ReleaseResources (bool close_filter)
 583                 {
 584                         if (close_filter && filter != null) {
 585                                 filter.Close ();
 586                                 filter = null;
 587                         }
 588
 589                         for (Bucket b = first_bucket; b != null; b = b.Next)
 590                                 b.Dispose ();
 591
 592                         first_bucket = null;
 593                         cur_bucket = null;
 594                 }
 595
 596                 public void Clear ()
 597                 {
 598                         //
 599                         // IMPORTANT: you must dispose *AFTER* using all the buckets Byte chunks might be
 600                         // split across two buckets if there is a file between the data.
 601                         //
 602                         ReleaseResources (false);
 603                         total = 0;
 604                 }
 605
 606                 // Do not use directly. Use memcpy.
 607                 static unsafe void memcpy4 (byte *dest, byte *src, int size) {
 608                         /*while (size >= 32) {
 609                                 // using long is better than int and slower than double
 610                                 // FIXME: enable this only on correct alignment or on platforms
 611                                 // that can tolerate unaligned reads/writes of doubles
 612                                 ((double*)dest) [0] = ((double*)src) [0];
 613                                 ((double*)dest) [1] = ((double*)src) [1];
 614                                 ((double*)dest) [2] = ((double*)src) [2];
 615                                 ((double*)dest) [3] = ((double*)src) [3];
 616                                 dest += 32;
 617                                 src += 32;
 618                                 size -= 32;
 619                         }*/
 620                         while (size >= 16) {
 621                                 ((int*)dest) [0] = ((int*)src) [0];
 622                                 ((int*)dest) [1] = ((int*)src) [1];
 623                                 ((int*)dest) [2] = ((int*)src) [2];
 624                                 ((int*)dest) [3] = ((int*)src) [3];
 625                                 dest += 16;
 626                                 src += 16;
 627                                 size -= 16;
 628                         }
 629                         while (size >= 4) {
 630                                 ((int*)dest) [0] = ((int*)src) [0];
 631                                 dest += 4;
 632                                 src += 4;
 633                                 size -= 4;
 634                         }
 635                         while (size > 0) {
 636                                 ((byte*)dest) [0] = ((byte*)src) [0];
 637                                 dest += 1;
 638                                 src += 1;
 639                                 --size;
 640                         }
 641                 }
 642
 643                 // Do not use directly. Use memcpy.
 644                 static unsafe void memcpy2 (byte *dest, byte *src, int size) {
 645                         while (size >= 8) {
 646                                 ((short*)dest) [0] = ((short*)src) [0];
 647                                 ((short*)dest) [1] = ((short*)src) [1];
 648                                 ((short*)dest) [2] = ((short*)src) [2];
 649                                 ((short*)dest) [3] = ((short*)src) [3];
 650                                 dest += 8;
 651                                 src += 8;
 652                                 size -= 8;
 653                         }
 654                         while (size >= 2) {
 655                                 ((short*)dest) [0] = ((short*)src) [0];
 656                                 dest += 2;
 657                                 src += 2;
 658                                 size -= 2;
 659                         }
 660                         if (size > 0)
 661                                 ((byte*)dest) [0] = ((byte*)src) [0];
 662                 }
 663
 664                 // Do not use directly. Use memcpy.
 665                 static unsafe void memcpy1 (byte *dest, byte *src, int size) {
 666                         while (size >= 8) {
 667                                 ((byte*)dest) [0] = ((byte*)src) [0];
 668                                 ((byte*)dest) [1] = ((byte*)src) [1];
 669                                 ((byte*)dest) [2] = ((byte*)src) [2];
 670                                 ((byte*)dest) [3] = ((byte*)src) [3];
 671                                 ((byte*)dest) [4] = ((byte*)src) [4];
 672                                 ((byte*)dest) [5] = ((byte*)src) [5];
 673                                 ((byte*)dest) [6] = ((byte*)src) [6];
 674                                 ((byte*)dest) [7] = ((byte*)src) [7];
 675                                 dest += 8;
 676                                 src += 8;
 677                                 size -= 8;
 678                         }
 679                         while (size >= 2) {
 680                                 ((byte*)dest) [0] = ((byte*)src) [0];
 681                                 ((byte*)dest) [1] = ((byte*)src) [1];
 682                                 dest += 2;
 683                                 src += 2;
 684                                 size -= 2;
 685                         }
 686                         if (size > 0)
 687                                 ((byte*)dest) [0] = ((byte*)src) [0];
 688                 }
 689
 690                 static unsafe void memcpy (byte *dest, byte *src, int size) {
 691                         // FIXME: if pointers are not aligned, try to align them
 692                         // so a faster routine can be used. Handle the case where
 693                         // the pointers can't be reduced to have the same alignment
 694                         // (just ignore the issue on x86?)
 695                         if ((((int)dest | (int)src) & 3) != 0) {
 696                                 if (((int)dest & 1) != 0 && ((int)src & 1) != 0 && size >= 1) {
 697                                         dest [0] = src [0];
 698                                         ++dest;
 699                                         ++src;
 700                                         --size;
 701                                 }
 702                                 if (((int)dest & 2) != 0 && ((int)src & 2) != 0 && size >= 2) {
 703                                         ((short*)dest) [0] = ((short*)src) [0];
 704                                         dest += 2;
 705                                         src += 2;
 706                                         size -= 2;
 707                                 }
 708                                 if ((((int)dest | (int)src) & 1) != 0) {
 709                                         memcpy1 (dest, src, size);
 710                                         return;
 711                                 }
 712                                 if ((((int)dest | (int)src) & 2) != 0) {
 713                                         memcpy2 (dest, src, size);
 714                                         return;
 715                                 }
 716                         }
 717                         memcpy4 (dest, src, size);
 718                 }
 719
 720                 public override bool CanRead {
 721                         get {
 722                                 return false;
 723                         }
 724                 }
 725
 726                 public override bool CanSeek {
 727                         get {
 728                                 return false;
 729                         }
 730                 }
 731                 public override bool CanWrite {
 732                         get {
 733                                 return true;
 734                         }
 735                 }
 736
 737                 const string notsupported = "HttpResponseStream is a forward, write-only stream";
 738
 739                 public override long Length {
 740                         get {
 741                                 throw new InvalidOperationException (notsupported);
 742                         }
 743                 }
 744
 745                 public override long Position {
 746                         get {
 747                                 throw new InvalidOperationException (notsupported);
 748                         }
 749                         set {
 750                                 throw new InvalidOperationException (notsupported);
 751                         }
 752                 }
 753
 754                 public override long Seek (long offset, SeekOrigin origin)
 755                 {
 756                         throw new InvalidOperationException (notsupported);
 757                 }
 758
 759                 public override void SetLength (long value)
 760                 {
 761                         throw new InvalidOperationException (notsupported);
 762                 }
 763
 764                 public override int Read (byte [] buffer, int offset, int count)
 765                 {
 766                         throw new InvalidOperationException (notsupported);
 767                 }
 768         }
 769 }
 770