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) 2005-2009 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         class HttpResponseStream : Stream
  51         {
  52                 Bucket first_bucket;
  53                 Bucket cur_bucket;
  54                 HttpResponse response;
  55                 internal long total;
  56                 Stream filter;
  57                 byte [] chunk_buffer = new byte [24];
  58
  59                 public HttpResponseStream (HttpResponse response)
  60                 {
  61                         this.response = response;
  62                 }
  63
  64                 internal bool HaveFilter {
  65                         get { return filter != null; }
  66                 }
  67
  68                 public Stream Filter {
  69                         get {
  70                                 if (filter == null)
  71                                         filter = new OutputFilterStream (this);
  72                                 return filter;
  73                         }
  74                         set {
  75                                 filter = value;
  76                         }
  77                 }
  78 #if TARGET_JVM
  79
  80                 class BlockManager {
  81                         const int PreferredLength = 16 * 1024;
  82                         static readonly byte[] EmptyBuffer = new byte[0];
  83
  84                         byte[] buffer = EmptyBuffer;
  85                         int position;
  86
  87                         public BlockManager () {
  88                         }
  89
  90                         public int Position {
  91                                 get { return position; }
  92                         }
  93
  94                         void EnsureCapacity (int capacity) {
  95                                 if (buffer.Length >= capacity)
  96                                         return;
  97
  98                                 capacity += PreferredLength;
  99                                 capacity = (capacity / PreferredLength) * PreferredLength;
 100                                 byte[] temp = new byte[capacity];
 101                                 Array.Copy(buffer, 0, temp, 0, buffer.Length);
 102                                 buffer = temp;
 103                         }
 104
 105                         public void Write (byte [] buffer, int offset, int count) {
 106                                 if (count == 0)
 107                                         return;
 108
 109                                 EnsureCapacity (position + count);
 110                                 Array.Copy(buffer, offset, this.buffer, position, count);
 111                                 position += count;
 112                         }
 113
 114                         public void Send (HttpWorkerRequest wr, int start, int end) {
 115                                 int length = end - start;
 116                                 if (length <= 0)
 117                                         return;
 118
 119                                 if (length > buffer.Length - start)
 120                                         length = buffer.Length - start;
 121
 122                                 if (start > 0) {
 123                                         byte[] temp = new byte[length];
 124                                         Array.Copy(buffer, start, temp, 0, length);
 125                                         buffer = temp;
 126                                 }
 127                                 wr.SendResponseFromMemory(buffer, length);
 128                         }
 129
 130                         public void Send (Stream stream, int start, int end) {
 131                                 int length = end - start;
 132                                 if (length <= 0)
 133                                         return;
 134
 135                                 if (length > buffer.Length - start)
 136                                         length = buffer.Length - start;
 137
 138                                 stream.Write(buffer, start, length);
 139                         }
 140
 141                         public void Dispose () {
 142                                 buffer = null;
 143                         }
 144                 }
 145
 146 #else // TARGET_JVM
 147                 unsafe sealed class BlockManager {
 148                         const int PreferredLength = 128 * 1024;
 149                         byte *data;
 150                         int position;
 151                         int block_size;
 152
 153                         public BlockManager ()
 154                         {
 155                         }
 156
 157                         public int Position {
 158                                 get { return position; }
 159                         }
 160
 161                         void EnsureCapacity (int capacity)
 162                         {
 163                                 if (block_size >= capacity)
 164                                         return;
 165
 166                                 capacity += PreferredLength;
 167                                 capacity = (capacity / PreferredLength) * PreferredLength;
 168
 169                                 data = data == null
 170                                         ? (byte *) Marshal.AllocHGlobal (capacity)
 171                                         : (byte *) Marshal.ReAllocHGlobal ((IntPtr) data, (IntPtr) capacity);
 172                                 block_size = capacity;
 173                         }
 174
 175                         public void Write (byte [] buffer, int offset, int count)
 176                         {
 177                                 if (count == 0)
 178                                         return;
 179
 180                                 EnsureCapacity (position + count);
 181                                 Marshal.Copy (buffer, offset, (IntPtr) (data + position), count);
 182                                 position += count;
 183                         }
 184
 185                         public void Write (IntPtr ptr, int count)
 186                         {
 187                                 if (count == 0)
 188                                         return;
 189
 190                                 EnsureCapacity (position + count);
 191                                 byte *src = (byte *) ptr.ToPointer ();
 192                                 memcpy (data + position, src, count);
 193                                 position += count;
 194                         }
 195
 196                         public void Send (HttpWorkerRequest wr, int start, int end)
 197                         {
 198                                 if (end - start <= 0)
 199                                         return;
 200
 201                                 wr.SendResponseFromMemory ((IntPtr) (data + start), end - start);
 202                         }
 203
 204                         public void Send (Stream stream, int start, int end)
 205                         {
 206                                 int len = end - start;
 207                                 if (len <= 0)
 208                                         return;
 209
 210                                 byte [] buffer = new byte [Math.Min (len, 32 * 1024)];
 211                                 int size = buffer.Length;
 212                                 while (len > 0) {
 213                                         Marshal.Copy ((IntPtr) (data + start), buffer, 0, size);
 214                                         stream.Write (buffer, 0, size);
 215                                         start += size;
 216                                         len -= size;
 217                                         if (len > 0 && len < size)
 218                                                 size = len;
 219                                 }
 220                         }
 221
 222                         public void Dispose ()
 223                         {
 224                                 if ((IntPtr) data != IntPtr.Zero) {
 225                                         Marshal.FreeHGlobal ((IntPtr) data);
 226                                         data = (byte *) IntPtr.Zero;
 227                                 }
 228                         }
 229                 }
 230
 231 #endif
 232                 abstract class Bucket {
 233                         public Bucket Next;
 234
 235                         public virtual void Dispose ()
 236                         {
 237                         }
 238
 239                         public abstract void Send (HttpWorkerRequest wr);
 240                         public abstract void Send (Stream stream);
 241                         public abstract int Length { get; }
 242                 }
 243
 244 #if !TARGET_JVM
 245                 unsafe
 246 #endif
 247                 class ByteBucket : Bucket {
 248                         int start;
 249                         int length;
 250                         public BlockManager blocks;
 251                         public bool Expandable = true;
 252
 253                         public ByteBucket () : this (null)
 254                         {
 255                         }
 256
 257                         public ByteBucket (BlockManager blocks)
 258                         {
 259                                 if (blocks == null)
 260                                         blocks = new BlockManager ();
 261
 262                                 this.blocks = blocks;
 263                                 start = blocks.Position;
 264                         }
 265
 266                         public override int Length {
 267                                 get { return length; }
 268                         }
 269
 270                         public unsafe int Write (byte [] buf, int offset, int count)
 271                         {
 272                                 if (Expandable == false)
 273                                         throw new Exception ("This should not happen.");
 274
 275                                 fixed (byte *p = &buf[0]) {
 276                                         IntPtr p2 = new IntPtr (p + offset);
 277                                         blocks.Write (p2, count);
 278                                 }
 279
 280                                 length += count;
 281                                 return count;
 282                         }
 283
 284                         public int Write (IntPtr ptr, int count)
 285                         {
 286                                 if (Expandable == false)
 287                                         throw new Exception ("This should not happen.");
 288
 289                                 blocks.Write (ptr, count);
 290                                 length += count;
 291                                 return count;
 292                         }
 293
 294                         public override void Dispose ()
 295                         {
 296                                 blocks.Dispose ();
 297                         }
 298
 299                         public override void Send (HttpWorkerRequest wr)
 300                         {
 301                                 if (length == 0)
 302                                         return;
 303
 304                                 blocks.Send (wr, start, length);
 305                         }
 306
 307                         public override void Send (Stream stream)
 308                         {
 309                                 if (length == 0)
 310                                         return;
 311
 312                                 blocks.Send (stream, start, length);
 313                         }
 314                 }
 315
 316                 class BufferedFileBucket : Bucket {
 317                         string file;
 318                         long offset;
 319                         long length;
 320
 321                         public BufferedFileBucket (string f, long off, long len)
 322                         {
 323                                 file = f;
 324                                 offset = off;
 325                                 length = len;
 326                         }
 327
 328                         public override int Length {
 329                                 get { return (int) length; }
 330                         }
 331
 332                         public override void Send (HttpWorkerRequest wr)
 333                         {
 334                                 wr.SendResponseFromFile (file, offset, length);
 335                         }
 336
 337                         public override void Send (Stream stream)
 338                         {
 339                                 using (FileStream fs = File.OpenRead (file)) {
 340                                         byte [] buffer = new byte [Math.Min (fs.Length, 32*1024)];
 341
 342                                         long remain = fs.Length;
 343                                         int n;
 344                                         while (remain > 0 && (n = fs.Read (buffer, 0, (int) Math.Min (remain, 32*1024))) != 0){
 345                                                 remain -= n;
 346                                                 stream.Write (buffer, 0, n);
 347                                         }
 348                                 }
 349                         }
 350
 351                         public override string ToString ()
 352                         {
 353                                 return "file " + file + " " + length.ToString () + " bytes from position " + offset.ToString ();
 354                         }
 355                 }
 356
 357                 void AppendBucket (Bucket b)
 358                 {
 359                         if (first_bucket == null) {
 360                                 cur_bucket = first_bucket = b;
 361                                 return;
 362                         }
 363
 364                         cur_bucket.Next = b;
 365                         cur_bucket = b;
 366                 }
 367
 368                 //
 369                 // Nothing happens here, broken by requirement.
 370                 // See note at the start
 371                 //
 372                 public override void Flush ()
 373                 {
 374                 }
 375
 376                 void SendChunkSize (long l, bool last)
 377                 {
 378                         if (l == 0 && !last)
 379                                 return;
 380
 381                         int i = 0;
 382                         if (l >= 0) {
 383                                 string s = l.ToString ("x");
 384                                 for (; i < s.Length; i++)
 385                                         chunk_buffer [i] = (byte) s [i];
 386                         }
 387
 388                         chunk_buffer [i++] = 13;
 389                         chunk_buffer [i++] = 10;
 390                         if (last) {
 391                                 chunk_buffer [i++] = 13;
 392                                 chunk_buffer [i++] = 10;
 393                         }
 394
 395                         response.WorkerRequest.SendResponseFromMemory (chunk_buffer, i);
 396                 }
 397
 398                 internal void Flush (HttpWorkerRequest wr, bool final_flush)
 399                 {
 400                         if (total == 0 && !final_flush)
 401                                 return;
 402
 403                         if (response.use_chunked)
 404                                 SendChunkSize (total, false);
 405
 406                         for (Bucket b = first_bucket; b != null; b = b.Next) {
 407                                 b.Send (wr);
 408                         }
 409
 410                         if (response.use_chunked) {
 411                                 SendChunkSize (-1, false);
 412                                 if (final_flush)
 413                                         SendChunkSize (0, true);
 414                         }
 415
 416                         wr.FlushResponse (final_flush);
 417
 418                         Clear ();
 419                 }
 420
 421                 internal int GetTotalLength ()
 422                 {
 423                         int size = 0;
 424                         for (Bucket b = first_bucket; b != null; b = b.Next)
 425                                 size += b.Length;
 426
 427                         return size;
 428                 }
 429
 430                 internal MemoryStream GetData ()
 431                 {
 432                         MemoryStream stream = new MemoryStream ();
 433                         for (Bucket b = first_bucket; b != null; b = b.Next)
 434                                 b.Send (stream);
 435                         return stream;
 436                 }
 437
 438                 public void WriteFile (string f, long offset, long length)
 439                 {
 440                         if (length == 0)
 441                                 return;
 442
 443                         ByteBucket bb = cur_bucket as ByteBucket;
 444
 445                         if (bb != null) {
 446                                 bb.Expandable = false;
 447                                 bb = new ByteBucket (bb.blocks);
 448                         }
 449
 450                         total += length;
 451
 452                         AppendBucket (new BufferedFileBucket (f, offset, length));
 453                         if (bb != null)
 454                                 AppendBucket (bb);
 455                         // Flush () is called from HttpResponse if needed (WriteFile/TransmitFile)
 456                 }
 457
 458                 bool filtering;
 459                 internal void ApplyFilter (bool close)
 460                 {
 461                         if (filter == null)
 462                                 return;
 463
 464                         filtering = true;
 465                         Bucket one = first_bucket;
 466                         first_bucket = null; // This will recreate new buckets for the filtered content
 467                         cur_bucket = null;
 468                         total = 0;
 469                         for (Bucket b = one; b != null; b = b.Next)
 470                                 b.Send (filter);
 471
 472                         for (Bucket b = one; b != null; b = b.Next)
 473                                 b.Dispose ();
 474
 475                         if (close) {
 476                                 filter.Flush ();
 477                                 filter.Close ();
 478                                 filter = null;
 479                         } else {
 480                                 filter.Flush ();
 481                         }
 482                         filtering = false;
 483                 }
 484
 485                 public void WritePtr (IntPtr ptr, int length)
 486                 {
 487                         if (length == 0)
 488                                 return;
 489
 490                         bool buffering = response.BufferOutput;
 491
 492                         if (buffering) {
 493                                 // It does not matter whether we're in ApplyFilter or not
 494                                 AppendBuffer (ptr, length);
 495                         } else if (filter == null || filtering) {
 496                                 response.WriteHeaders (false);
 497                                 HttpWorkerRequest wr = response.WorkerRequest;
 498                                 // Direct write because not buffering
 499                                 wr.SendResponseFromMemory (ptr, length);
 500                                 wr.FlushResponse (false);
 501                         } else {
 502                                 // Write to the filter, which will call us back, and then Flush
 503                                 filtering = true;
 504                                 try {
 505                                         byte [] bytes = new byte [length];
 506                                         Marshal.Copy (ptr, bytes, 0, length);
 507                                         filter.Write (bytes, 0, length);
 508                                         bytes = null;
 509                                 } finally {
 510                                         filtering = false;
 511                                 }
 512                                 Flush (response.WorkerRequest, false);
 513                         }
 514
 515                 }
 516
 517                 public override void Write (byte [] buffer, int offset, int count)
 518                 {
 519                         bool buffering = response.BufferOutput;
 520                         if (buffer == null)
 521                                 throw new ArgumentNullException ("buffer");
 522
 523                         int max_count = buffer.Length - offset;
 524                         if (offset < 0 || max_count <= 0)
 525                                 throw new ArgumentOutOfRangeException ("offset");
 526                         if (count < 0)
 527                                 throw new ArgumentOutOfRangeException ("count");
 528                         if (count > max_count)
 529                                 count = max_count;
 530
 531                         if (buffering) {
 532                                 // It does not matter whether we're in ApplyFilter or not
 533                                 AppendBuffer (buffer, offset, count);
 534                         } else if (filter == null || filtering) {
 535                                 response.WriteHeaders (false);
 536                                 HttpWorkerRequest wr = response.WorkerRequest;
 537                                 // Direct write because not buffering
 538                                 if (offset == 0) {
 539                                         wr.SendResponseFromMemory (buffer, count);
 540                                 } else {
 541                                         UnsafeWrite (wr, buffer, offset, count);
 542                                 }
 543                                 wr.FlushResponse (false);
 544                         } else {
 545                                 // Write to the filter, which will call us back, and then Flush
 546                                 filtering = true;
 547                                 try {
 548                                         filter.Write (buffer, offset, count);
 549                                 } finally {
 550                                         filtering = false;
 551                                 }
 552                                 Flush (response.WorkerRequest, false);
 553                         }
 554                 }
 555
 556 #if TARGET_JVM
 557                 void UnsafeWrite (HttpWorkerRequest wr, byte [] buffer, int offset, int count)
 558                 {
 559                         if (count <= 0)
 560                                 return;
 561
 562                         byte[] copy = new byte[count];
 563                         Array.Copy(buffer, offset, copy, 0, count);
 564                         wr.SendResponseFromMemory (copy, count);
 565                 }
 566 #else
 567                 unsafe void UnsafeWrite (HttpWorkerRequest wr, byte [] buffer, int offset, int count)
 568                 {
 569                         fixed (byte *ptr = buffer) {
 570                                 wr.SendResponseFromMemory ((IntPtr) (ptr + offset), count);
 571                         }
 572                 }
 573 #endif
 574                 void AppendBuffer (byte [] buffer, int offset, int count)
 575                 {
 576                         if (!(cur_bucket is ByteBucket))
 577                                 AppendBucket (new ByteBucket ());
 578
 579                         total += count;
 580                         ((ByteBucket) cur_bucket).Write (buffer, offset, count);
 581                 }
 582
 583                 void AppendBuffer (IntPtr ptr, int count)
 584                 {
 585                         if (!(cur_bucket is ByteBucket))
 586                                 AppendBucket (new ByteBucket ());
 587
 588                         total += count;
 589                         ((ByteBucket) cur_bucket).Write (ptr, count);
 590                 }
 591
 592                 //
 593                 // This should not flush/close or anything else, its called
 594                 // just to free any memory we might have allocated (when we later
 595                 // implement something with unmanaged memory).
 596                 //
 597                 internal void ReleaseResources (bool close_filter)
 598                 {
 599                         if (close_filter && filter != null) {
 600                                 filter.Close ();
 601                                 filter = null;
 602                         }
 603
 604                         for (Bucket b = first_bucket; b != null; b = b.Next)
 605                                 b.Dispose ();
 606
 607                         first_bucket = null;
 608                         cur_bucket = null;
 609                 }
 610
 611                 public void Clear ()
 612                 {
 613                         //
 614                         // IMPORTANT: you must dispose *AFTER* using all the buckets Byte chunks might be
 615                         // split across two buckets if there is a file between the data.
 616                         //
 617                         ReleaseResources (false);
 618                         total = 0;
 619                 }
 620
 621                 // Do not use directly. Use memcpy.
 622                 static unsafe void memcpy4 (byte *dest, byte *src, int size) {
 623                         /*while (size >= 32) {
 624                                 // using long is better than int and slower than double
 625                                 // FIXME: enable this only on correct alignment or on platforms
 626                                 // that can tolerate unaligned reads/writes of doubles
 627                                 ((double*)dest) [0] = ((double*)src) [0];
 628                                 ((double*)dest) [1] = ((double*)src) [1];
 629                                 ((double*)dest) [2] = ((double*)src) [2];
 630                                 ((double*)dest) [3] = ((double*)src) [3];
 631                                 dest += 32;
 632                                 src += 32;
 633                                 size -= 32;
 634                         }*/
 635                         while (size >= 16) {
 636                                 ((int*)dest) [0] = ((int*)src) [0];
 637                                 ((int*)dest) [1] = ((int*)src) [1];
 638                                 ((int*)dest) [2] = ((int*)src) [2];
 639                                 ((int*)dest) [3] = ((int*)src) [3];
 640                                 dest += 16;
 641                                 src += 16;
 642                                 size -= 16;
 643                         }
 644                         while (size >= 4) {
 645                                 ((int*)dest) [0] = ((int*)src) [0];
 646                                 dest += 4;
 647                                 src += 4;
 648                                 size -= 4;
 649                         }
 650                         while (size > 0) {
 651                                 ((byte*)dest) [0] = ((byte*)src) [0];
 652                                 dest += 1;
 653                                 src += 1;
 654                                 --size;
 655                         }
 656                 }
 657
 658                 // Do not use directly. Use memcpy.
 659                 static unsafe void memcpy2 (byte *dest, byte *src, int size) {
 660                         while (size >= 8) {
 661                                 ((short*)dest) [0] = ((short*)src) [0];
 662                                 ((short*)dest) [1] = ((short*)src) [1];
 663                                 ((short*)dest) [2] = ((short*)src) [2];
 664                                 ((short*)dest) [3] = ((short*)src) [3];
 665                                 dest += 8;
 666                                 src += 8;
 667                                 size -= 8;
 668                         }
 669                         while (size >= 2) {
 670                                 ((short*)dest) [0] = ((short*)src) [0];
 671                                 dest += 2;
 672                                 src += 2;
 673                                 size -= 2;
 674                         }
 675                         if (size > 0)
 676                                 ((byte*)dest) [0] = ((byte*)src) [0];
 677                 }
 678
 679                 // Do not use directly. Use memcpy.
 680                 static unsafe void memcpy1 (byte *dest, byte *src, int size) {
 681                         while (size >= 8) {
 682                                 ((byte*)dest) [0] = ((byte*)src) [0];
 683                                 ((byte*)dest) [1] = ((byte*)src) [1];
 684                                 ((byte*)dest) [2] = ((byte*)src) [2];
 685                                 ((byte*)dest) [3] = ((byte*)src) [3];
 686                                 ((byte*)dest) [4] = ((byte*)src) [4];
 687                                 ((byte*)dest) [5] = ((byte*)src) [5];
 688                                 ((byte*)dest) [6] = ((byte*)src) [6];
 689                                 ((byte*)dest) [7] = ((byte*)src) [7];
 690                                 dest += 8;
 691                                 src += 8;
 692                                 size -= 8;
 693                         }
 694                         while (size >= 2) {
 695                                 ((byte*)dest) [0] = ((byte*)src) [0];
 696                                 ((byte*)dest) [1] = ((byte*)src) [1];
 697                                 dest += 2;
 698                                 src += 2;
 699                                 size -= 2;
 700                         }
 701                         if (size > 0)
 702                                 ((byte*)dest) [0] = ((byte*)src) [0];
 703                 }
 704
 705                 static unsafe void memcpy (byte *dest, byte *src, int size) {
 706                         // FIXME: if pointers are not aligned, try to align them
 707                         // so a faster routine can be used. Handle the case where
 708                         // the pointers can't be reduced to have the same alignment
 709                         // (just ignore the issue on x86?)
 710                         if ((((int)dest | (int)src) & 3) != 0) {
 711                                 if (((int)dest & 1) != 0 && ((int)src & 1) != 0 && size >= 1) {
 712                                         dest [0] = src [0];
 713                                         ++dest;
 714                                         ++src;
 715                                         --size;
 716                                 }
 717                                 if (((int)dest & 2) != 0 && ((int)src & 2) != 0 && size >= 2) {
 718                                         ((short*)dest) [0] = ((short*)src) [0];
 719                                         dest += 2;
 720                                         src += 2;
 721                                         size -= 2;
 722                                 }
 723                                 if ((((int)dest | (int)src) & 1) != 0) {
 724                                         memcpy1 (dest, src, size);
 725                                         return;
 726                                 }
 727                                 if ((((int)dest | (int)src) & 2) != 0) {
 728                                         memcpy2 (dest, src, size);
 729                                         return;
 730                                 }
 731                         }
 732                         memcpy4 (dest, src, size);
 733                 }
 734
 735                 public override bool CanRead {
 736                         get {
 737                                 return false;
 738                         }
 739                 }
 740
 741                 public override bool CanSeek {
 742                         get {
 743                                 return false;
 744                         }
 745                 }
 746
 747                 public override bool CanWrite {
 748                         get {
 749                                 return true;
 750                         }
 751                 }
 752
 753                 const string notsupported = "HttpResponseStream is a forward, write-only stream";
 754
 755                 public override long Length {
 756                         get {
 757                                 throw new NotSupportedException (notsupported);
 758                         }
 759                 }
 760
 761                 public override long Position {
 762                         get {
 763                                 throw new NotSupportedException (notsupported);
 764                         }
 765                         set {
 766                                 throw new NotSupportedException (notsupported);
 767                         }
 768                 }
 769
 770                 public override long Seek (long offset, SeekOrigin origin)
 771                 {
 772                         throw new NotSupportedException (notsupported);
 773                 }
 774
 775                 public override void SetLength (long value)
 776                 {
 777                         throw new NotSupportedException (notsupported);
 778                 }
 779
 780                 public override int Read (byte [] buffer, int offset, int count)
 781                 {
 782                         throw new NotSupportedException (notsupported);
 783                 }
 784         }
 785 }