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 //
   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                                 byte [] newBuffer = null;
 167                                 if (value != 0) {
 168                                         newBuffer = new byte [value];
 169                                         Buffer.BlockCopy (internalBuffer, 0, newBuffer, 0, length);
 170                                 }
 171
 172                                 dirty_bytes = 0; // discard any dirty area beyond previous length
 173                                 internalBuffer = newBuffer; // It's null when capacity is set to 0
 174                                 capacity = value;
 175                         }
 176                 }
 177
 178                 public override long Length {
 179                         get {
 180                                 // LAMESPEC: The spec says to throw an IOException if the
 181                                 // stream is closed and an ObjectDisposedException if
 182                                 // "methods were called after the stream was closed".  What
 183                                 // is the difference?
 184
 185                                 CheckIfClosedThrowDisposed ();
 186
 187                                 // This is ok for MemoryStreamTest.ConstructorFive
 188                                 return length - initialIndex;
 189                         }
 190                 }
 191
 192                 public override long Position {
 193                         get {
 194                                 CheckIfClosedThrowDisposed ();
 195                                 return position - initialIndex;
 196                         }
 197
 198                         set {
 199                                 CheckIfClosedThrowDisposed ();
 200                                 if (value < 0)
 201                                         throw new ArgumentOutOfRangeException ("value",
 202                                                                 "Position cannot be negative" );
 203
 204                                 if (value > Int32.MaxValue)
 205                                         throw new ArgumentOutOfRangeException ("value",
 206                                         "Position must be non-negative and less than 2^31 - 1 - origin");
 207
 208                                 position = initialIndex + (int) value;
 209                         }
 210                 }
 211
 212                 protected override void Dispose (bool disposing)
 213                 {
 214                         streamClosed = true;
 215                         expandable = false;
 216                 }
 217
 218                 public override void Flush ()
 219                 {
 220                         // Do nothing
 221                 }
 222
 223                 public virtual byte [] GetBuffer ()
 224                 {
 225                         if (!allowGetBuffer)
 226                                 throw new UnauthorizedAccessException ();
 227
 228                         return internalBuffer;
 229                 }
 230
 231                 public override int Read ([In,Out] byte [] buffer, int offset, int count)
 232                 {
 233                         CheckIfClosedThrowDisposed ();
 234
 235                         if (buffer == null)
 236                                 throw new ArgumentNullException ("buffer");
 237
 238                         if (offset < 0 || count < 0)
 239                                 throw new ArgumentOutOfRangeException ("offset or count less than zero.");
 240
 241                         if (buffer.Length - offset < count )
 242                                 throw new ArgumentException ("offset+count",
 243                                                               "The size of the buffer is less than offset + count.");
 244
 245                         if (position >= length || count == 0)
 246                                 return 0;
 247
 248                         if (position > length - count)
 249                                 count = length - position;
 250
 251                         Buffer.BlockCopy (internalBuffer, position, buffer, offset, count);
 252                         position += count;
 253                         return count;
 254                 }
 255
 256                 public override int ReadByte ()
 257                 {
 258                         CheckIfClosedThrowDisposed ();
 259                         if (position >= length)
 260                                 return -1;
 261
 262                         return internalBuffer [position++];
 263                 }
 264
 265                 public override long Seek (long offset, SeekOrigin loc)
 266                 {
 267                         CheckIfClosedThrowDisposed ();
 268
 269                         // It's funny that they don't throw this exception for < Int32.MinValue
 270                         if (offset > (long) Int32.MaxValue)
 271                                 throw new ArgumentOutOfRangeException ("Offset out of range. " + offset);
 272
 273                         int refPoint;
 274                         switch (loc) {
 275                         case SeekOrigin.Begin:
 276                                 if (offset < 0)
 277                                         throw new IOException ("Attempted to seek before start of MemoryStream.");
 278                                 refPoint = initialIndex;
 279                                 break;
 280                         case SeekOrigin.Current:
 281                                 refPoint = position;
 282                                 break;
 283                         case SeekOrigin.End:
 284                                 refPoint = length;
 285                                 break;
 286                         default:
 287                                 throw new ArgumentException ("loc", "Invalid SeekOrigin");
 288                         }
 289
 290                         // LAMESPEC: My goodness, how may LAMESPECs are there in this
 291                         // class! :)  In the spec for the Position property it's stated
 292                         // "The position must not be more than one byte beyond the end of the stream."
 293                         // In the spec for seek it says "Seeking to any location beyond the length of the
 294                         // stream is supported."  That's a contradiction i'd say.
 295                         // I guess seek can go anywhere but if you use position it may get moved back.
 296
 297                         refPoint += (int) offset;
 298                         if (refPoint < initialIndex)
 299                                 throw new IOException ("Attempted to seek before start of MemoryStream.");
 300
 301                         position = refPoint;
 302                         return position;
 303                 }
 304
 305                 int CalculateNewCapacity (int minimum)
 306                 {
 307                         if (minimum < 256)
 308                                 minimum = 256; // See GetBufferTwo test
 309
 310                         if (minimum < capacity * 2)
 311                                 minimum = capacity * 2;
 312
 313                         return minimum;
 314                 }
 315
 316                 void Expand (int newSize)
 317                 {
 318                         // We don't need to take into account the dirty bytes when incrementing the
 319                         // Capacity, as changing it will only preserve the valid clear region.
 320                         if (newSize > capacity)
 321                                 Capacity = CalculateNewCapacity (newSize);
 322                         else if (dirty_bytes > 0) {
 323                                 Array.Clear (internalBuffer, length, dirty_bytes);
 324                                 dirty_bytes = 0;
 325                         }
 326                 }
 327
 328                 public override void SetLength (long value)
 329                 {
 330                         if (!expandable && value > capacity)
 331                                 throw new NotSupportedException ("Expanding this MemoryStream is not supported");
 332
 333                         CheckIfClosedThrowDisposed ();
 334
 335                         if (!canWrite) {
 336                                 throw new NotSupportedException (Locale.GetText
 337                                         ("Cannot write to this MemoryStream"));
 338                         }
 339
 340                         // LAMESPEC: AGAIN! It says to throw this exception if value is
 341                         // greater than "the maximum length of the MemoryStream".  I haven't
 342                         // seen anywhere mention what the maximum length of a MemoryStream is and
 343                         // since we're this far this memory stream is expandable.
 344                         if (value < 0 || (value + initialIndex) > (long) Int32.MaxValue)
 345                                 throw new ArgumentOutOfRangeException ();
 346
 347                         int newSize = (int) value + initialIndex;
 348
 349                         if (newSize > length)
 350                                 Expand (newSize);
 351                         else if (newSize < length) // Postpone the call to Array.Clear till expand time
 352                                 dirty_bytes += length - newSize;
 353
 354                         length = newSize;
 355                         if (position > length)
 356                                 position = length;
 357                 }
 358
 359                 public virtual byte [] ToArray ()
 360                 {
 361                         int l = length - initialIndex;
 362                         byte[] outBuffer = new byte [l];
 363
 364                         if (internalBuffer != null)
 365                                 Buffer.BlockCopy (internalBuffer, initialIndex, outBuffer, 0, l);
 366                         return outBuffer;
 367                 }
 368
 369                 public override void Write (byte [] buffer, int offset, int count)
 370                 {
 371                         CheckIfClosedThrowDisposed ();
 372
 373                         if (!canWrite)
 374                                 throw new NotSupportedException ("Cannot write to this stream.");
 375
 376                         if (buffer == null)
 377                                 throw new ArgumentNullException ("buffer");
 378
 379                         if (offset < 0 || count < 0)
 380                                 throw new ArgumentOutOfRangeException ();
 381
 382                         if (buffer.Length - offset < count)
 383                                 throw new ArgumentException ("offset+count",
 384                                                              "The size of the buffer is less than offset + count.");
 385
 386                         // reordered to avoid possible integer overflow
 387                         if (position > length - count)
 388                                 Expand (position + count);
 389
 390                         Buffer.BlockCopy (buffer, offset, internalBuffer, position, count);
 391                         position += count;
 392                         if (position >= length)
 393                                 length = position;
 394                 }
 395
 396                 public override void WriteByte (byte value)
 397                 {
 398                         CheckIfClosedThrowDisposed ();
 399                         if (!canWrite)
 400                                 throw new NotSupportedException ("Cannot write to this stream.");
 401
 402                         if (position >= length) {
 403                                 Expand (position + 1);
 404                                 length = position + 1;
 405                         }
 406
 407                         internalBuffer [position++] = value;
 408                 }
 409
 410                 public virtual void WriteTo (Stream stream)
 411                 {
 412                         CheckIfClosedThrowDisposed ();
 413
 414                         if (stream == null)
 415                                 throw new ArgumentNullException ("stream");
 416
 417                         stream.Write (internalBuffer, initialIndex, length - initialIndex);
 418                 }
 419
 420 #if NET_4_0
 421                 public override void ObjectInvariant ()
 422                 {
 423                 }
 424 #endif
 425         }
 426 }