mcs/class/corlib/System.IO/MemoryStream.cs

   1 //
   2 // System.IO.MemoryStream.cs
   3 //
   4 // Authors:     Marcin Szczepanski (marcins@zipworld.com.au)
   5 //              Patrik Torstensson
   6 //              Gonzalo Paniagua Javier (gonzalo@ximian.com)
   7 //              Marek Safar (marek.safar@gmail.com)
   8 //
   9 // (c) 2001,2002 Marcin Szczepanski, Patrik Torstensson
  10 // (c) 2003 Ximian, Inc. (http://www.ximian.com)
  11 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  12 // Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
  13 //
  14 // Permission is hereby granted, free of charge, to any person obtaining
  15 // a copy of this software and associated documentation files (the
  16 // "Software"), to deal in the Software without restriction, including
  17 // without limitation the rights to use, copy, modify, merge, publish,
  18 // distribute, sublicense, and/or sell copies of the Software, and to
  19 // permit persons to whom the Software is furnished to do so, subject to
  20 // the following conditions:
  21 //
  22 // The above copyright notice and this permission notice shall be
  23 // included in all copies or substantial portions of the Software.
  24 //
  25 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  26 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  27 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  28 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  29 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  30 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  31 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  32 //
  33
  34 using System.Globalization;
  35 using System.Runtime.InteropServices;
  36 using System.Threading;
  37 #if NET_4_5
  38 using System.Threading.Tasks;
  39 #endif
  40
  41 namespace System.IO
  42 {
  43         [Serializable]
  44         [ComVisible (true)]
  45         [MonoLimitation ("Serialization format not compatible with .NET")]
  46         public class MemoryStream : Stream
  47         {
  48                 bool canWrite;
  49                 bool allowGetBuffer;
  50                 int capacity;
  51                 int length;
  52                 byte [] internalBuffer;
  53                 int initialIndex;
  54                 bool expandable;
  55                 bool streamClosed;
  56                 int position;
  57                 int dirty_bytes;
  58 #if NET_4_5
  59                 [NonSerialized]
  60                 Task<int> read_task;
  61 #endif
  62
  63                 public MemoryStream () : this (0)
  64                 {
  65                 }
  66
  67                 public MemoryStream (int capacity)
  68                 {
  69                         if (capacity < 0)
  70                                 throw new ArgumentOutOfRangeException ("capacity");
  71
  72                         canWrite = true;
  73
  74                         this.capacity = capacity;
  75                         internalBuffer = new byte [capacity];
  76
  77                         expandable = true;
  78                         allowGetBuffer = true;
  79                 }
  80
  81                 public MemoryStream (byte [] buffer)
  82                 {
  83                         if (buffer == null)
  84                                 throw new ArgumentNullException ("buffer");
  85
  86                         InternalConstructor (buffer, 0, buffer.Length, true, false);
  87                 }
  88
  89                 public MemoryStream (byte [] buffer, bool writable)
  90                 {
  91                         if (buffer == null)
  92                                 throw new ArgumentNullException ("buffer");
  93
  94                         InternalConstructor (buffer, 0, buffer.Length, writable, false);
  95                 }
  96
  97                 public MemoryStream (byte [] buffer, int index, int count)
  98                 {
  99                         InternalConstructor (buffer, index, count, true, false);
 100                 }
 101
 102                 public MemoryStream (byte [] buffer, int index, int count, bool writable)
 103                 {
 104                         InternalConstructor (buffer, index, count, writable, false);
 105                 }
 106
 107                 public MemoryStream (byte [] buffer, int index, int count, bool writable, bool publiclyVisible)
 108                 {
 109                         InternalConstructor (buffer, index, count, writable, publiclyVisible);
 110                 }
 111
 112                 void InternalConstructor (byte [] buffer, int index, int count, bool writable, bool publicallyVisible)
 113                 {
 114                         if (buffer == null)
 115                                 throw new ArgumentNullException ("buffer");
 116
 117                         if (index < 0 || count < 0)
 118                                 throw new ArgumentOutOfRangeException ("index or count is less than 0.");
 119
 120                         if (buffer.Length - index < count)
 121                                 throw new ArgumentException ("index+count",
 122                                                              "The size of the buffer is less than index + count.");
 123
 124                         canWrite = writable;
 125
 126                         internalBuffer = buffer;
 127                         capacity = count + index;
 128                         length = capacity;
 129                         position = index;
 130                         initialIndex = index;
 131
 132                         allowGetBuffer = publicallyVisible;
 133                         expandable = false;
 134                 }
 135
 136                 void CheckIfClosedThrowDisposed ()
 137                 {
 138                         if (streamClosed)
 139                                 throw new ObjectDisposedException ("MemoryStream");
 140                 }
 141
 142                 public override bool CanRead {
 143                         get { return !streamClosed; }
 144                 }
 145
 146                 public override bool CanSeek {
 147                         get { return !streamClosed; }
 148                 }
 149
 150                 public override bool CanWrite {
 151                         get { return (!streamClosed && canWrite); }
 152                 }
 153
 154                 public virtual int Capacity {
 155                         get {
 156                                 CheckIfClosedThrowDisposed ();
 157                                 return capacity - initialIndex;
 158                         }
 159
 160                         set {
 161                                 CheckIfClosedThrowDisposed ();
 162
 163                                 if (!expandable)
 164                                         throw new NotSupportedException ("Cannot expand this MemoryStream");
 165
 166                                 if (value < 0 || value < length)
 167                                         throw new ArgumentOutOfRangeException ("value",
 168                                         "New capacity cannot be negative or less than the current capacity " + value + " " + capacity);
 169
 170                                 if (internalBuffer != null && value == internalBuffer.Length)
 171                                         return;
 172
 173                                 byte [] newBuffer = null;
 174                                 if (value != 0) {
 175                                         newBuffer = new byte [value];
 176                                         if (internalBuffer != null)
 177                                                 Buffer.BlockCopy (internalBuffer, 0, newBuffer, 0, length);
 178                                 }
 179
 180                                 dirty_bytes = 0; // discard any dirty area beyond previous length
 181                                 internalBuffer = newBuffer; // It's null when capacity is set to 0
 182                                 capacity = value;
 183                         }
 184                 }
 185
 186                 public override long Length {
 187                         get {
 188                                 // LAMESPEC: The spec says to throw an IOException if the
 189                                 // stream is closed and an ObjectDisposedException if
 190                                 // "methods were called after the stream was closed".  What
 191                                 // is the difference?
 192
 193                                 CheckIfClosedThrowDisposed ();
 194
 195                                 // This is ok for MemoryStreamTest.ConstructorFive
 196                                 return length - initialIndex;
 197                         }
 198                 }
 199
 200                 public override long Position {
 201                         get {
 202                                 CheckIfClosedThrowDisposed ();
 203                                 return position - initialIndex;
 204                         }
 205
 206                         set {
 207                                 CheckIfClosedThrowDisposed ();
 208                                 if (value < 0)
 209                                         throw new ArgumentOutOfRangeException ("value",
 210                                                                 "Position cannot be negative" );
 211
 212                                 if (value > Int32.MaxValue)
 213                                         throw new ArgumentOutOfRangeException ("value",
 214                                         "Position must be non-negative and less than 2^31 - 1 - origin");
 215
 216                                 position = initialIndex + (int) value;
 217                         }
 218                 }
 219
 220                 protected override void Dispose (bool disposing)
 221                 {
 222                         streamClosed = true;
 223                         expandable = false;
 224                 }
 225
 226                 public override void Flush ()
 227                 {
 228                         // Do nothing
 229                 }
 230
 231                 public virtual byte [] GetBuffer ()
 232                 {
 233                         if (!allowGetBuffer)
 234                                 throw new UnauthorizedAccessException ();
 235
 236                         return internalBuffer;
 237                 }
 238
 239                 public override int Read ([In,Out] byte [] buffer, int offset, int count)
 240                 {
 241                         if (buffer == null)
 242                                 throw new ArgumentNullException ("buffer");
 243
 244                         if (offset < 0 || count < 0)
 245                                 throw new ArgumentOutOfRangeException ("offset or count less than zero.");
 246
 247                         if (buffer.Length - offset < count )
 248                                 throw new ArgumentException ("offset+count",
 249                                                               "The size of the buffer is less than offset + count.");
 250
 251                         CheckIfClosedThrowDisposed ();
 252
 253                         if (position >= length || count == 0)
 254                                 return 0;
 255
 256                         if (position > length - count)
 257                                 count = length - position;
 258
 259                         Buffer.BlockCopy (internalBuffer, position, buffer, offset, count);
 260                         position += count;
 261                         return count;
 262                 }
 263
 264                 public override int ReadByte ()
 265                 {
 266                         CheckIfClosedThrowDisposed ();
 267                         if (position >= length)
 268                                 return -1;
 269
 270                         return internalBuffer [position++];
 271                 }
 272
 273                 public override long Seek (long offset, SeekOrigin loc)
 274                 {
 275                         CheckIfClosedThrowDisposed ();
 276
 277                         // It's funny that they don't throw this exception for < Int32.MinValue
 278                         if (offset > (long) Int32.MaxValue)
 279                                 throw new ArgumentOutOfRangeException ("Offset out of range. " + offset);
 280
 281                         int refPoint;
 282                         switch (loc) {
 283                         case SeekOrigin.Begin:
 284                                 if (offset < 0)
 285                                         throw new IOException ("Attempted to seek before start of MemoryStream.");
 286                                 refPoint = initialIndex;
 287                                 break;
 288                         case SeekOrigin.Current:
 289                                 refPoint = position;
 290                                 break;
 291                         case SeekOrigin.End:
 292                                 refPoint = length;
 293                                 break;
 294                         default:
 295                                 throw new ArgumentException ("loc", "Invalid SeekOrigin");
 296                         }
 297
 298                         // LAMESPEC: My goodness, how may LAMESPECs are there in this
 299                         // class! :)  In the spec for the Position property it's stated
 300                         // "The position must not be more than one byte beyond the end of the stream."
 301                         // In the spec for seek it says "Seeking to any location beyond the length of the
 302                         // stream is supported."  That's a contradiction i'd say.
 303                         // I guess seek can go anywhere but if you use position it may get moved back.
 304
 305                         refPoint += (int) offset;
 306                         if (refPoint < initialIndex)
 307                                 throw new IOException ("Attempted to seek before start of MemoryStream.");
 308
 309                         position = refPoint;
 310                         return position;
 311                 }
 312
 313                 int CalculateNewCapacity (int minimum)
 314                 {
 315                         if (minimum < 256)
 316                                 minimum = 256; // See GetBufferTwo test
 317
 318                         if (minimum < capacity * 2)
 319                                 minimum = capacity * 2;
 320
 321                         return minimum;
 322                 }
 323
 324                 void Expand (int newSize)
 325                 {
 326                         // We don't need to take into account the dirty bytes when incrementing the
 327                         // Capacity, as changing it will only preserve the valid clear region.
 328                         if (newSize > capacity)
 329                                 Capacity = CalculateNewCapacity (newSize);
 330                         else if (dirty_bytes > 0) {
 331                                 Array.Clear (internalBuffer, length, dirty_bytes);
 332                                 dirty_bytes = 0;
 333                         }
 334                 }
 335
 336                 public override void SetLength (long value)
 337                 {
 338                         if (!expandable && value > capacity)
 339                                 throw new NotSupportedException ("Expanding this MemoryStream is not supported");
 340
 341                         CheckIfClosedThrowDisposed ();
 342
 343                         if (!canWrite) {
 344                                 throw new NotSupportedException (Locale.GetText
 345                                         ("Cannot write to this MemoryStream"));
 346                         }
 347
 348                         // LAMESPEC: AGAIN! It says to throw this exception if value is
 349                         // greater than "the maximum length of the MemoryStream".  I haven't
 350                         // seen anywhere mention what the maximum length of a MemoryStream is and
 351                         // since we're this far this memory stream is expandable.
 352                         if (value < 0 || (value + initialIndex) > (long) Int32.MaxValue)
 353                                 throw new ArgumentOutOfRangeException ();
 354
 355                         int newSize = (int) value + initialIndex;
 356
 357                         if (newSize > length)
 358                                 Expand (newSize);
 359                         else if (newSize < length) // Postpone the call to Array.Clear till expand time
 360                                 dirty_bytes += length - newSize;
 361
 362                         length = newSize;
 363                         if (position > length)
 364                                 position = length;
 365                 }
 366
 367                 public virtual byte [] ToArray ()
 368                 {
 369                         int l = length - initialIndex;
 370                         byte[] outBuffer = new byte [l];
 371
 372                         if (internalBuffer != null)
 373                                 Buffer.BlockCopy (internalBuffer, initialIndex, outBuffer, 0, l);
 374                         return outBuffer;
 375                 }
 376
 377                 public override void Write (byte [] buffer, int offset, int count)
 378                 {
 379                         if (!canWrite)
 380                                 throw new NotSupportedException ("Cannot write to this stream.");
 381
 382                         if (buffer == null)
 383                                 throw new ArgumentNullException ("buffer");
 384
 385                         if (offset < 0 || count < 0)
 386                                 throw new ArgumentOutOfRangeException ();
 387
 388                         if (buffer.Length - offset < count)
 389                                 throw new ArgumentException ("offset+count",
 390                                                              "The size of the buffer is less than offset + count.");
 391
 392                         CheckIfClosedThrowDisposed ();
 393
 394                         // reordered to avoid possible integer overflow
 395                         if (position > length - count)
 396                                 Expand (position + count);
 397
 398                         Buffer.BlockCopy (buffer, offset, internalBuffer, position, count);
 399                         position += count;
 400                         if (position >= length)
 401                                 length = position;
 402                 }
 403
 404                 public override void WriteByte (byte value)
 405                 {
 406                         CheckIfClosedThrowDisposed ();
 407                         if (!canWrite)
 408                                 throw new NotSupportedException ("Cannot write to this stream.");
 409
 410                         if (position >= length) {
 411                                 Expand (position + 1);
 412                                 length = position + 1;
 413                         }
 414
 415                         internalBuffer [position++] = value;
 416                 }
 417
 418                 public virtual void WriteTo (Stream stream)
 419                 {
 420                         CheckIfClosedThrowDisposed ();
 421
 422                         if (stream == null)
 423                                 throw new ArgumentNullException ("stream");
 424
 425                         stream.Write (internalBuffer, initialIndex, length - initialIndex);
 426                 }
 427
 428 #if NET_4_5
 429
 430                 public override Task CopyToAsync (Stream destination, int bufferSize, CancellationToken cancellationToken)
 431                 {
 432                         // TODO: Specialization but what for?
 433                         return base.CopyToAsync (destination, bufferSize, cancellationToken);
 434                 }
 435
 436                 public override Task FlushAsync (CancellationToken cancellationToken)
 437                 {
 438                         if (cancellationToken.IsCancellationRequested)
 439                                 return TaskConstants<int>.Canceled;
 440
 441                         Flush ();
 442                         return TaskConstants.Finished;
 443                 }
 444
 445                 public override Task<int> ReadAsync (byte[] buffer, int offset, int count, CancellationToken cancellationToken)
 446                 {
 447                         if (cancellationToken.IsCancellationRequested)
 448                                 return TaskConstants<int>.Canceled;
 449
 450                         count = Read (buffer, offset, count);
 451
 452                         // Try not to allocate a new task for every buffer read
 453                         if (read_task == null || read_task.Result != count)
 454                                 read_task = Task<int>.FromResult (count);
 455
 456                         return read_task;
 457                 }
 458
 459                 public override Task WriteAsync (byte[] buffer, int offset, int count, CancellationToken cancellationToken)
 460                 {
 461                         if (cancellationToken.IsCancellationRequested)
 462                                 return TaskConstants<int>.Canceled;
 463
 464                         Write (buffer, offset, count);
 465                         return TaskConstants.Finished;
 466                 }
 467 #endif
 468         }
 469 }