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                 Task<int> read_task;
  60 #endif
  61
  62                 public MemoryStream () : this (0)
  63                 {
  64                 }
  65
  66                 public MemoryStream (int capacity)
  67                 {
  68                         if (capacity < 0)
  69                                 throw new ArgumentOutOfRangeException ("capacity");
  70
  71                         canWrite = true;
  72
  73                         this.capacity = capacity;
  74                         internalBuffer = new byte [capacity];
  75
  76                         expandable = true;
  77                         allowGetBuffer = true;
  78                 }
  79
  80                 public MemoryStream (byte [] buffer)
  81                 {
  82                         if (buffer == null)
  83                                 throw new ArgumentNullException ("buffer");
  84
  85                         InternalConstructor (buffer, 0, buffer.Length, true, false);
  86                 }
  87
  88                 public MemoryStream (byte [] buffer, bool writable)
  89                 {
  90                         if (buffer == null)
  91                                 throw new ArgumentNullException ("buffer");
  92
  93                         InternalConstructor (buffer, 0, buffer.Length, writable, false);
  94                 }
  95
  96                 public MemoryStream (byte [] buffer, int index, int count)
  97                 {
  98                         InternalConstructor (buffer, index, count, true, false);
  99                 }
 100
 101                 public MemoryStream (byte [] buffer, int index, int count, bool writable)
 102                 {
 103                         InternalConstructor (buffer, index, count, writable, false);
 104                 }
 105
 106                 public MemoryStream (byte [] buffer, int index, int count, bool writable, bool publiclyVisible)
 107                 {
 108                         InternalConstructor (buffer, index, count, writable, publiclyVisible);
 109                 }
 110
 111                 void InternalConstructor (byte [] buffer, int index, int count, bool writable, bool publicallyVisible)
 112                 {
 113                         if (buffer == null)
 114                                 throw new ArgumentNullException ("buffer");
 115
 116                         if (index < 0 || count < 0)
 117                                 throw new ArgumentOutOfRangeException ("index or count is less than 0.");
 118
 119                         if (buffer.Length - index < count)
 120                                 throw new ArgumentException ("index+count",
 121                                                              "The size of the buffer is less than index + count.");
 122
 123                         canWrite = writable;
 124
 125                         internalBuffer = buffer;
 126                         capacity = count + index;
 127                         length = capacity;
 128                         position = index;
 129                         initialIndex = index;
 130
 131                         allowGetBuffer = publicallyVisible;
 132                         expandable = false;
 133                 }
 134
 135                 void CheckIfClosedThrowDisposed ()
 136                 {
 137                         if (streamClosed)
 138                                 throw new ObjectDisposedException ("MemoryStream");
 139                 }
 140
 141                 public override bool CanRead {
 142                         get { return !streamClosed; }
 143                 }
 144
 145                 public override bool CanSeek {
 146                         get { return !streamClosed; }
 147                 }
 148
 149                 public override bool CanWrite {
 150                         get { return (!streamClosed && canWrite); }
 151                 }
 152
 153                 public virtual int Capacity {
 154                         get {
 155                                 CheckIfClosedThrowDisposed ();
 156                                 return capacity - initialIndex;
 157                         }
 158
 159                         set {
 160                                 CheckIfClosedThrowDisposed ();
 161
 162                                 if (!expandable)
 163                                         throw new NotSupportedException ("Cannot expand this MemoryStream");
 164
 165                                 if (value < 0 || value < length)
 166                                         throw new ArgumentOutOfRangeException ("value",
 167                                         "New capacity cannot be negative or less than the current capacity " + value + " " + capacity);
 168
 169                                 if (internalBuffer != null && value == internalBuffer.Length)
 170                                         return;
 171
 172                                 byte [] newBuffer = null;
 173                                 if (value != 0) {
 174                                         newBuffer = new byte [value];
 175                                         if (internalBuffer != null)
 176                                                 Buffer.BlockCopy (internalBuffer, 0, newBuffer, 0, length);
 177                                 }
 178
 179                                 dirty_bytes = 0; // discard any dirty area beyond previous length
 180                                 internalBuffer = newBuffer; // It's null when capacity is set to 0
 181                                 capacity = value;
 182                         }
 183                 }
 184
 185                 public override long Length {
 186                         get {
 187                                 // LAMESPEC: The spec says to throw an IOException if the
 188                                 // stream is closed and an ObjectDisposedException if
 189                                 // "methods were called after the stream was closed".  What
 190                                 // is the difference?
 191
 192                                 CheckIfClosedThrowDisposed ();
 193
 194                                 // This is ok for MemoryStreamTest.ConstructorFive
 195                                 return length - initialIndex;
 196                         }
 197                 }
 198
 199                 public override long Position {
 200                         get {
 201                                 CheckIfClosedThrowDisposed ();
 202                                 return position - initialIndex;
 203                         }
 204
 205                         set {
 206                                 CheckIfClosedThrowDisposed ();
 207                                 if (value < 0)
 208                                         throw new ArgumentOutOfRangeException ("value",
 209                                                                 "Position cannot be negative" );
 210
 211                                 if (value > Int32.MaxValue)
 212                                         throw new ArgumentOutOfRangeException ("value",
 213                                         "Position must be non-negative and less than 2^31 - 1 - origin");
 214
 215                                 position = initialIndex + (int) value;
 216                         }
 217                 }
 218
 219                 protected override void Dispose (bool disposing)
 220                 {
 221                         streamClosed = true;
 222                         expandable = false;
 223                 }
 224
 225                 public override void Flush ()
 226                 {
 227                         // Do nothing
 228                 }
 229
 230                 public virtual byte [] GetBuffer ()
 231                 {
 232                         if (!allowGetBuffer)
 233                                 throw new UnauthorizedAccessException ();
 234
 235                         return internalBuffer;
 236                 }
 237
 238                 public override int Read ([In,Out] byte [] buffer, int offset, int count)
 239                 {
 240                         if (buffer == null)
 241                                 throw new ArgumentNullException ("buffer");
 242
 243                         if (offset < 0 || count < 0)
 244                                 throw new ArgumentOutOfRangeException ("offset or count less than zero.");
 245
 246                         if (buffer.Length - offset < count )
 247                                 throw new ArgumentException ("offset+count",
 248                                                               "The size of the buffer is less than offset + count.");
 249
 250                         CheckIfClosedThrowDisposed ();
 251
 252                         if (position >= length || count == 0)
 253                                 return 0;
 254
 255                         if (position > length - count)
 256                                 count = length - position;
 257
 258                         Buffer.BlockCopy (internalBuffer, position, buffer, offset, count);
 259                         position += count;
 260                         return count;
 261                 }
 262
 263                 public override int ReadByte ()
 264                 {
 265                         CheckIfClosedThrowDisposed ();
 266                         if (position >= length)
 267                                 return -1;
 268
 269                         return internalBuffer [position++];
 270                 }
 271
 272                 public override long Seek (long offset, SeekOrigin loc)
 273                 {
 274                         CheckIfClosedThrowDisposed ();
 275
 276                         // It's funny that they don't throw this exception for < Int32.MinValue
 277                         if (offset > (long) Int32.MaxValue)
 278                                 throw new ArgumentOutOfRangeException ("Offset out of range. " + offset);
 279
 280                         int refPoint;
 281                         switch (loc) {
 282                         case SeekOrigin.Begin:
 283                                 if (offset < 0)
 284                                         throw new IOException ("Attempted to seek before start of MemoryStream.");
 285                                 refPoint = initialIndex;
 286                                 break;
 287                         case SeekOrigin.Current:
 288                                 refPoint = position;
 289                                 break;
 290                         case SeekOrigin.End:
 291                                 refPoint = length;
 292                                 break;
 293                         default:
 294                                 throw new ArgumentException ("loc", "Invalid SeekOrigin");
 295                         }
 296
 297                         // LAMESPEC: My goodness, how may LAMESPECs are there in this
 298                         // class! :)  In the spec for the Position property it's stated
 299                         // "The position must not be more than one byte beyond the end of the stream."
 300                         // In the spec for seek it says "Seeking to any location beyond the length of the
 301                         // stream is supported."  That's a contradiction i'd say.
 302                         // I guess seek can go anywhere but if you use position it may get moved back.
 303
 304                         refPoint += (int) offset;
 305                         if (refPoint < initialIndex)
 306                                 throw new IOException ("Attempted to seek before start of MemoryStream.");
 307
 308                         position = refPoint;
 309                         return position;
 310                 }
 311
 312                 int CalculateNewCapacity (int minimum)
 313                 {
 314                         if (minimum < 256)
 315                                 minimum = 256; // See GetBufferTwo test
 316
 317                         if (minimum < capacity * 2)
 318                                 minimum = capacity * 2;
 319
 320                         return minimum;
 321                 }
 322
 323                 void Expand (int newSize)
 324                 {
 325                         // We don't need to take into account the dirty bytes when incrementing the
 326                         // Capacity, as changing it will only preserve the valid clear region.
 327                         if (newSize > capacity)
 328                                 Capacity = CalculateNewCapacity (newSize);
 329                         else if (dirty_bytes > 0) {
 330                                 Array.Clear (internalBuffer, length, dirty_bytes);
 331                                 dirty_bytes = 0;
 332                         }
 333                 }
 334
 335                 public override void SetLength (long value)
 336                 {
 337                         if (!expandable && value > capacity)
 338                                 throw new NotSupportedException ("Expanding this MemoryStream is not supported");
 339
 340                         CheckIfClosedThrowDisposed ();
 341
 342                         if (!canWrite) {
 343                                 throw new NotSupportedException (Locale.GetText
 344                                         ("Cannot write to this MemoryStream"));
 345                         }
 346
 347                         // LAMESPEC: AGAIN! It says to throw this exception if value is
 348                         // greater than "the maximum length of the MemoryStream".  I haven't
 349                         // seen anywhere mention what the maximum length of a MemoryStream is and
 350                         // since we're this far this memory stream is expandable.
 351                         if (value < 0 || (value + initialIndex) > (long) Int32.MaxValue)
 352                                 throw new ArgumentOutOfRangeException ();
 353
 354                         int newSize = (int) value + initialIndex;
 355
 356                         if (newSize > length)
 357                                 Expand (newSize);
 358                         else if (newSize < length) // Postpone the call to Array.Clear till expand time
 359                                 dirty_bytes += length - newSize;
 360
 361                         length = newSize;
 362                         if (position > length)
 363                                 position = length;
 364                 }
 365
 366                 public virtual byte [] ToArray ()
 367                 {
 368                         int l = length - initialIndex;
 369                         byte[] outBuffer = new byte [l];
 370
 371                         if (internalBuffer != null)
 372                                 Buffer.BlockCopy (internalBuffer, initialIndex, outBuffer, 0, l);
 373                         return outBuffer;
 374                 }
 375
 376                 public override void Write (byte [] buffer, int offset, int count)
 377                 {
 378                         if (!canWrite)
 379                                 throw new NotSupportedException ("Cannot write to this stream.");
 380
 381                         if (buffer == null)
 382                                 throw new ArgumentNullException ("buffer");
 383
 384                         if (offset < 0 || count < 0)
 385                                 throw new ArgumentOutOfRangeException ();
 386
 387                         if (buffer.Length - offset < count)
 388                                 throw new ArgumentException ("offset+count",
 389                                                              "The size of the buffer is less than offset + count.");
 390
 391                         CheckIfClosedThrowDisposed ();
 392
 393                         // reordered to avoid possible integer overflow
 394                         if (position > length - count)
 395                                 Expand (position + count);
 396
 397                         Buffer.BlockCopy (buffer, offset, internalBuffer, position, count);
 398                         position += count;
 399                         if (position >= length)
 400                                 length = position;
 401                 }
 402
 403                 public override void WriteByte (byte value)
 404                 {
 405                         CheckIfClosedThrowDisposed ();
 406                         if (!canWrite)
 407                                 throw new NotSupportedException ("Cannot write to this stream.");
 408
 409                         if (position >= length) {
 410                                 Expand (position + 1);
 411                                 length = position + 1;
 412                         }
 413
 414                         internalBuffer [position++] = value;
 415                 }
 416
 417                 public virtual void WriteTo (Stream stream)
 418                 {
 419                         CheckIfClosedThrowDisposed ();
 420
 421                         if (stream == null)
 422                                 throw new ArgumentNullException ("stream");
 423
 424                         stream.Write (internalBuffer, initialIndex, length - initialIndex);
 425                 }
 426
 427 #if NET_4_5
 428
 429                 public override Task CopyToAsync (Stream destination, int bufferSize, CancellationToken cancellationToken)
 430                 {
 431                         // TODO: Specialization but what for?
 432                         return base.CopyToAsync (destination, bufferSize, cancellationToken);
 433                 }
 434
 435                 public override Task FlushAsync (CancellationToken cancellationToken)
 436                 {
 437                         if (cancellationToken.IsCancellationRequested)
 438                                 return TaskConstants<int>.Canceled;
 439
 440                         Flush ();
 441                         return TaskConstants.Finished;
 442                 }
 443
 444                 public override Task<int> ReadAsync (byte[] buffer, int offset, int count, CancellationToken cancellationToken)
 445                 {
 446                         if (cancellationToken.IsCancellationRequested)
 447                                 return TaskConstants<int>.Canceled;
 448
 449                         count = Read (buffer, offset, count);
 450
 451                         // Try not to allocate a new task for every buffer read
 452                         if (read_task == null || read_task.Result != count)
 453                                 read_task = Task<int>.FromResult (count);
 454
 455                         return read_task;
 456                 }
 457
 458                 public override Task WriteAsync (byte[] buffer, int offset, int count, CancellationToken cancellationToken)
 459                 {
 460                         if (cancellationToken.IsCancellationRequested)
 461                                 return TaskConstants<int>.Canceled;
 462
 463                         Write (buffer, offset, count);
 464                         return TaskConstants.Finished;
 465                 }
 466 #endif
 467         }
 468 }