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 //
   8 // (c) 2001,2002 Marcin Szczepanski, Patrik Torstensson
   9 // (c) 2003 Ximian, Inc. (http://www.ximian.com)
  10 // Copyright (C) 2004 Novell (http://www.novell.com)
  11 //
  12
  13 //
  14 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  15 //
  16 // Permission is hereby granted, free of charge, to any person obtaining
  17 // a copy of this software and associated documentation files (the
  18 // "Software"), to deal in the Software without restriction, including
  19 // without limitation the rights to use, copy, modify, merge, publish,
  20 // distribute, sublicense, and/or sell copies of the Software, and to
  21 // permit persons to whom the Software is furnished to do so, subject to
  22 // the following conditions:
  23 //
  24 // The above copyright notice and this permission notice shall be
  25 // included in all copies or substantial portions of the Software.
  26 //
  27 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  28 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  29 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  30 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  31 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  32 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  33 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  34 //
  35
  36 using System.Globalization;
  37 using System.Runtime.InteropServices;
  38
  39 namespace System.IO
  40 {
  41         [Serializable]
  42         [ComVisible (true)]
  43         [MonoLimitation ("Serialization format not compatible with .NET")]
  44         public class MemoryStream : Stream
  45         {
  46                 bool canWrite;
  47                 bool allowGetBuffer;
  48                 int capacity;
  49                 int length;
  50                 byte [] internalBuffer;
  51                 int initialIndex;
  52                 bool expandable;
  53                 bool streamClosed;
  54                 int position;
  55                 int dirty_bytes;
  56
  57                 public MemoryStream () : this (0)
  58                 {
  59                 }
  60
  61                 public MemoryStream (int capacity)
  62                 {
  63                         if (capacity < 0)
  64                                 throw new ArgumentOutOfRangeException ("capacity");
  65
  66                         canWrite = true;
  67
  68                         this.capacity = capacity;
  69                         internalBuffer = new byte [capacity];
  70
  71                         expandable = true;
  72                         allowGetBuffer = true;
  73                 }
  74
  75                 public MemoryStream (byte [] buffer)
  76                 {
  77                         if (buffer == null)
  78                                 throw new ArgumentNullException ("buffer");
  79
  80                         InternalConstructor (buffer, 0, buffer.Length, true, false);
  81                 }
  82
  83                 public MemoryStream (byte [] buffer, bool writable)
  84                 {
  85                         if (buffer == null)
  86                                 throw new ArgumentNullException ("buffer");
  87
  88                         InternalConstructor (buffer, 0, buffer.Length, writable, false);
  89                 }
  90
  91                 public MemoryStream (byte [] buffer, int index, int count)
  92                 {
  93                         InternalConstructor (buffer, index, count, true, false);
  94                 }
  95
  96                 public MemoryStream (byte [] buffer, int index, int count, bool writable)
  97                 {
  98                         InternalConstructor (buffer, index, count, writable, false);
  99                 }
 100
 101                 public MemoryStream (byte [] buffer, int index, int count, bool writable, bool publiclyVisible)
 102                 {
 103                         InternalConstructor (buffer, index, count, writable, publiclyVisible);
 104                 }
 105
 106                 void InternalConstructor (byte [] buffer, int index, int count, bool writable, bool publicallyVisible)
 107                 {
 108                         if (buffer == null)
 109                                 throw new ArgumentNullException ("buffer");
 110
 111                         if (index < 0 || count < 0)
 112                                 throw new ArgumentOutOfRangeException ("index or count is less than 0.");
 113
 114                         if (buffer.Length - index < count)
 115                                 throw new ArgumentException ("index+count",
 116                                                              "The size of the buffer is less than index + count.");
 117
 118                         canWrite = writable;
 119
 120                         internalBuffer = buffer;
 121                         capacity = count + index;
 122                         length = capacity;
 123                         position = index;
 124                         initialIndex = index;
 125
 126                         allowGetBuffer = publicallyVisible;
 127                         expandable = false;
 128                 }
 129
 130                 void CheckIfClosedThrowDisposed ()
 131                 {
 132                         if (streamClosed)
 133                                 throw new ObjectDisposedException ("MemoryStream");
 134                 }
 135
 136                 public override bool CanRead {
 137                         get { return !streamClosed; }
 138                 }
 139
 140                 public override bool CanSeek {
 141                         get { return !streamClosed; }
 142                 }
 143
 144                 public override bool CanWrite {
 145                         get { return (!streamClosed && canWrite); }
 146                 }
 147
 148                 public virtual int Capacity {
 149                         get {
 150                                 CheckIfClosedThrowDisposed ();
 151                                 return capacity - initialIndex;
 152                         }
 153
 154                         set {
 155                                 CheckIfClosedThrowDisposed ();
 156                                 if (value == capacity)
 157                                         return; // LAMENESS: see MemoryStreamTest.ConstructorFive
 158
 159                                 if (!expandable)
 160                                         throw new NotSupportedException ("Cannot expand this MemoryStream");
 161
 162                                 if (value < 0 || value < length)
 163                                         throw new ArgumentOutOfRangeException ("value",
 164                                         "New capacity cannot be negative or less than the current capacity " + value + " " + capacity);
 165
 166                                 if (value == internalBuffer.Length)
 167                                         return;
 168
 169                                 byte [] newBuffer = null;
 170                                 if (value != 0) {
 171                                         newBuffer = new byte [value];
 172                                         Buffer.BlockCopy (internalBuffer, 0, newBuffer, 0, length);
 173                                 }
 174
 175                                 dirty_bytes = 0; // discard any dirty area beyond previous length
 176                                 internalBuffer = newBuffer; // It's null when capacity is set to 0
 177                                 capacity = value;
 178                         }
 179                 }
 180
 181                 public override long Length {
 182                         get {
 183                                 // LAMESPEC: The spec says to throw an IOException if the
 184                                 // stream is closed and an ObjectDisposedException if
 185                                 // "methods were called after the stream was closed".  What
 186                                 // is the difference?
 187
 188                                 CheckIfClosedThrowDisposed ();
 189
 190                                 // This is ok for MemoryStreamTest.ConstructorFive
 191                                 return length - initialIndex;
 192                         }
 193                 }
 194
 195                 public override long Position {
 196                         get {
 197                                 CheckIfClosedThrowDisposed ();
 198                                 return position - initialIndex;
 199                         }
 200
 201                         set {
 202                                 CheckIfClosedThrowDisposed ();
 203                                 if (value < 0)
 204                                         throw new ArgumentOutOfRangeException ("value",
 205                                                                 "Position cannot be negative" );
 206
 207                                 if (value > Int32.MaxValue)
 208                                         throw new ArgumentOutOfRangeException ("value",
 209                                         "Position must be non-negative and less than 2^31 - 1 - origin");
 210
 211                                 position = initialIndex + (int) value;
 212                         }
 213                 }
 214
 215                 protected override void Dispose (bool disposing)
 216                 {
 217                         streamClosed = true;
 218                         expandable = false;
 219                 }
 220
 221                 public override void Flush ()
 222                 {
 223                         // Do nothing
 224                 }
 225
 226                 public virtual byte [] GetBuffer ()
 227                 {
 228                         if (!allowGetBuffer)
 229                                 throw new UnauthorizedAccessException ();
 230
 231                         return internalBuffer;
 232                 }
 233
 234                 public override int Read ([In,Out] byte [] buffer, int offset, int count)
 235                 {
 236                         CheckIfClosedThrowDisposed ();
 237
 238                         if (buffer == null)
 239                                 throw new ArgumentNullException ("buffer");
 240
 241                         if (offset < 0 || count < 0)
 242                                 throw new ArgumentOutOfRangeException ("offset or count less than zero.");
 243
 244                         if (buffer.Length - offset < count )
 245                                 throw new ArgumentException ("offset+count",
 246                                                               "The size of the buffer is less than offset + count.");
 247
 248                         if (position >= length || count == 0)
 249                                 return 0;
 250
 251                         if (position > length - count)
 252                                 count = length - position;
 253
 254                         Buffer.BlockCopy (internalBuffer, position, buffer, offset, count);
 255                         position += count;
 256                         return count;
 257                 }
 258
 259                 public override int ReadByte ()
 260                 {
 261                         CheckIfClosedThrowDisposed ();
 262                         if (position >= length)
 263                                 return -1;
 264
 265                         return internalBuffer [position++];
 266                 }
 267
 268                 public override long Seek (long offset, SeekOrigin loc)
 269                 {
 270                         CheckIfClosedThrowDisposed ();
 271
 272                         // It's funny that they don't throw this exception for < Int32.MinValue
 273                         if (offset > (long) Int32.MaxValue)
 274                                 throw new ArgumentOutOfRangeException ("Offset out of range. " + offset);
 275
 276                         int refPoint;
 277                         switch (loc) {
 278                         case SeekOrigin.Begin:
 279                                 if (offset < 0)
 280                                         throw new IOException ("Attempted to seek before start of MemoryStream.");
 281                                 refPoint = initialIndex;
 282                                 break;
 283                         case SeekOrigin.Current:
 284                                 refPoint = position;
 285                                 break;
 286                         case SeekOrigin.End:
 287                                 refPoint = length;
 288                                 break;
 289                         default:
 290                                 throw new ArgumentException ("loc", "Invalid SeekOrigin");
 291                         }
 292
 293                         // LAMESPEC: My goodness, how may LAMESPECs are there in this
 294                         // class! :)  In the spec for the Position property it's stated
 295                         // "The position must not be more than one byte beyond the end of the stream."
 296                         // In the spec for seek it says "Seeking to any location beyond the length of the
 297                         // stream is supported."  That's a contradiction i'd say.
 298                         // I guess seek can go anywhere but if you use position it may get moved back.
 299
 300                         refPoint += (int) offset;
 301                         if (refPoint < initialIndex)
 302                                 throw new IOException ("Attempted to seek before start of MemoryStream.");
 303
 304                         position = refPoint;
 305                         return position;
 306                 }
 307
 308                 int CalculateNewCapacity (int minimum)
 309                 {
 310                         if (minimum < 256)
 311                                 minimum = 256; // See GetBufferTwo test
 312
 313                         if (minimum < capacity * 2)
 314                                 minimum = capacity * 2;
 315
 316                         return minimum;
 317                 }
 318
 319                 void Expand (int newSize)
 320                 {
 321                         // We don't need to take into account the dirty bytes when incrementing the
 322                         // Capacity, as changing it will only preserve the valid clear region.
 323                         if (newSize > capacity)
 324                                 Capacity = CalculateNewCapacity (newSize);
 325                         else if (dirty_bytes > 0) {
 326                                 Array.Clear (internalBuffer, length, dirty_bytes);
 327                                 dirty_bytes = 0;
 328                         }
 329                 }
 330
 331                 public override void SetLength (long value)
 332                 {
 333                         if (!expandable && value > capacity)
 334                                 throw new NotSupportedException ("Expanding this MemoryStream is not supported");
 335
 336                         CheckIfClosedThrowDisposed ();
 337
 338                         if (!canWrite) {
 339                                 throw new NotSupportedException (Locale.GetText
 340                                         ("Cannot write to this MemoryStream"));
 341                         }
 342
 343                         // LAMESPEC: AGAIN! It says to throw this exception if value is
 344                         // greater than "the maximum length of the MemoryStream".  I haven't
 345                         // seen anywhere mention what the maximum length of a MemoryStream is and
 346                         // since we're this far this memory stream is expandable.
 347                         if (value < 0 || (value + initialIndex) > (long) Int32.MaxValue)
 348                                 throw new ArgumentOutOfRangeException ();
 349
 350                         int newSize = (int) value + initialIndex;
 351
 352                         if (newSize > length)
 353                                 Expand (newSize);
 354                         else if (newSize < length) // Postpone the call to Array.Clear till expand time
 355                                 dirty_bytes += length - newSize;
 356
 357                         length = newSize;
 358                         if (position > length)
 359                                 position = length;
 360                 }
 361
 362                 public virtual byte [] ToArray ()
 363                 {
 364                         int l = length - initialIndex;
 365                         byte[] outBuffer = new byte [l];
 366
 367                         if (internalBuffer != null)
 368                                 Buffer.BlockCopy (internalBuffer, initialIndex, outBuffer, 0, l);
 369                         return outBuffer;
 370                 }
 371
 372                 public override void Write (byte [] buffer, int offset, int count)
 373                 {
 374                         CheckIfClosedThrowDisposed ();
 375
 376                         if (!canWrite)
 377                                 throw new NotSupportedException ("Cannot write to this stream.");
 378
 379                         if (buffer == null)
 380                                 throw new ArgumentNullException ("buffer");
 381
 382                         if (offset < 0 || count < 0)
 383                                 throw new ArgumentOutOfRangeException ();
 384
 385                         if (buffer.Length - offset < count)
 386                                 throw new ArgumentException ("offset+count",
 387                                                              "The size of the buffer is less than offset + count.");
 388
 389                         // reordered to avoid possible integer overflow
 390                         if (position > length - count)
 391                                 Expand (position + count);
 392
 393                         Buffer.BlockCopy (buffer, offset, internalBuffer, position, count);
 394                         position += count;
 395                         if (position >= length)
 396                                 length = position;
 397                 }
 398
 399                 public override void WriteByte (byte value)
 400                 {
 401                         CheckIfClosedThrowDisposed ();
 402                         if (!canWrite)
 403                                 throw new NotSupportedException ("Cannot write to this stream.");
 404
 405                         if (position >= length) {
 406                                 Expand (position + 1);
 407                                 length = position + 1;
 408                         }
 409
 410                         internalBuffer [position++] = value;
 411                 }
 412
 413                 public virtual void WriteTo (Stream stream)
 414                 {
 415                         CheckIfClosedThrowDisposed ();
 416
 417                         if (stream == null)
 418                                 throw new ArgumentNullException ("stream");
 419
 420                         stream.Write (internalBuffer, initialIndex, length - initialIndex);
 421                 }
 422
 423 #if NET_4_0
 424                 protected override void ObjectInvariant ()
 425                 {
 426                 }
 427 #endif
 428         }
 429 }