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
 157                                 if (!expandable)
 158                                         throw new NotSupportedException ("Cannot expand this MemoryStream");
 159
 160                                 if (value < 0 || value < length)
 161                                         throw new ArgumentOutOfRangeException ("value",
 162                                         "New capacity cannot be negative or less than the current capacity " + value + " " + capacity);
 163
 164                                 if (internalBuffer != null && value == internalBuffer.Length)
 165                                         return;
 166
 167                                 byte [] newBuffer = null;
 168                                 if (value != 0) {
 169                                         newBuffer = new byte [value];
 170                                         if (internalBuffer != null)
 171                                                 Buffer.BlockCopy (internalBuffer, 0, newBuffer, 0, length);
 172                                 }
 173
 174                                 dirty_bytes = 0; // discard any dirty area beyond previous length
 175                                 internalBuffer = newBuffer; // It's null when capacity is set to 0
 176                                 capacity = value;
 177                         }
 178                 }
 179
 180                 public override long Length {
 181                         get {
 182                                 // LAMESPEC: The spec says to throw an IOException if the
 183                                 // stream is closed and an ObjectDisposedException if
 184                                 // "methods were called after the stream was closed".  What
 185                                 // is the difference?
 186
 187                                 CheckIfClosedThrowDisposed ();
 188
 189                                 // This is ok for MemoryStreamTest.ConstructorFive
 190                                 return length - initialIndex;
 191                         }
 192                 }
 193
 194                 public override long Position {
 195                         get {
 196                                 CheckIfClosedThrowDisposed ();
 197                                 return position - initialIndex;
 198                         }
 199
 200                         set {
 201                                 CheckIfClosedThrowDisposed ();
 202                                 if (value < 0)
 203                                         throw new ArgumentOutOfRangeException ("value",
 204                                                                 "Position cannot be negative" );
 205
 206                                 if (value > Int32.MaxValue)
 207                                         throw new ArgumentOutOfRangeException ("value",
 208                                         "Position must be non-negative and less than 2^31 - 1 - origin");
 209
 210                                 position = initialIndex + (int) value;
 211                         }
 212                 }
 213
 214                 protected override void Dispose (bool disposing)
 215                 {
 216                         streamClosed = true;
 217                         expandable = false;
 218                 }
 219
 220                 public override void Flush ()
 221                 {
 222                         // Do nothing
 223                 }
 224
 225                 public virtual byte [] GetBuffer ()
 226                 {
 227                         if (!allowGetBuffer)
 228                                 throw new UnauthorizedAccessException ();
 229
 230                         return internalBuffer;
 231                 }
 232
 233                 public override int Read ([In,Out] byte [] buffer, int offset, int count)
 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                         CheckIfClosedThrowDisposed ();
 246
 247                         if (position >= length || count == 0)
 248                                 return 0;
 249
 250                         if (position > length - count)
 251                                 count = length - position;
 252
 253                         Buffer.BlockCopy (internalBuffer, position, buffer, offset, count);
 254                         position += count;
 255                         return count;
 256                 }
 257
 258                 public override int ReadByte ()
 259                 {
 260                         CheckIfClosedThrowDisposed ();
 261                         if (position >= length)
 262                                 return -1;
 263
 264                         return internalBuffer [position++];
 265                 }
 266
 267                 public override long Seek (long offset, SeekOrigin loc)
 268                 {
 269                         CheckIfClosedThrowDisposed ();
 270
 271                         // It's funny that they don't throw this exception for < Int32.MinValue
 272                         if (offset > (long) Int32.MaxValue)
 273                                 throw new ArgumentOutOfRangeException ("Offset out of range. " + offset);
 274
 275                         int refPoint;
 276                         switch (loc) {
 277                         case SeekOrigin.Begin:
 278                                 if (offset < 0)
 279                                         throw new IOException ("Attempted to seek before start of MemoryStream.");
 280                                 refPoint = initialIndex;
 281                                 break;
 282                         case SeekOrigin.Current:
 283                                 refPoint = position;
 284                                 break;
 285                         case SeekOrigin.End:
 286                                 refPoint = length;
 287                                 break;
 288                         default:
 289                                 throw new ArgumentException ("loc", "Invalid SeekOrigin");
 290                         }
 291
 292                         // LAMESPEC: My goodness, how may LAMESPECs are there in this
 293                         // class! :)  In the spec for the Position property it's stated
 294                         // "The position must not be more than one byte beyond the end of the stream."
 295                         // In the spec for seek it says "Seeking to any location beyond the length of the
 296                         // stream is supported."  That's a contradiction i'd say.
 297                         // I guess seek can go anywhere but if you use position it may get moved back.
 298
 299                         refPoint += (int) offset;
 300                         if (refPoint < initialIndex)
 301                                 throw new IOException ("Attempted to seek before start of MemoryStream.");
 302
 303                         position = refPoint;
 304                         return position;
 305                 }
 306
 307                 int CalculateNewCapacity (int minimum)
 308                 {
 309                         if (minimum < 256)
 310                                 minimum = 256; // See GetBufferTwo test
 311
 312                         if (minimum < capacity * 2)
 313                                 minimum = capacity * 2;
 314
 315                         return minimum;
 316                 }
 317
 318                 void Expand (int newSize)
 319                 {
 320                         // We don't need to take into account the dirty bytes when incrementing the
 321                         // Capacity, as changing it will only preserve the valid clear region.
 322                         if (newSize > capacity)
 323                                 Capacity = CalculateNewCapacity (newSize);
 324                         else if (dirty_bytes > 0) {
 325                                 Array.Clear (internalBuffer, length, dirty_bytes);
 326                                 dirty_bytes = 0;
 327                         }
 328                 }
 329
 330                 public override void SetLength (long value)
 331                 {
 332                         if (!expandable && value > capacity)
 333                                 throw new NotSupportedException ("Expanding this MemoryStream is not supported");
 334
 335                         CheckIfClosedThrowDisposed ();
 336
 337                         if (!canWrite) {
 338                                 throw new NotSupportedException (Locale.GetText
 339                                         ("Cannot write to this MemoryStream"));
 340                         }
 341
 342                         // LAMESPEC: AGAIN! It says to throw this exception if value is
 343                         // greater than "the maximum length of the MemoryStream".  I haven't
 344                         // seen anywhere mention what the maximum length of a MemoryStream is and
 345                         // since we're this far this memory stream is expandable.
 346                         if (value < 0 || (value + initialIndex) > (long) Int32.MaxValue)
 347                                 throw new ArgumentOutOfRangeException ();
 348
 349                         int newSize = (int) value + initialIndex;
 350
 351                         if (newSize > length)
 352                                 Expand (newSize);
 353                         else if (newSize < length) // Postpone the call to Array.Clear till expand time
 354                                 dirty_bytes += length - newSize;
 355
 356                         length = newSize;
 357                         if (position > length)
 358                                 position = length;
 359                 }
 360
 361                 public virtual byte [] ToArray ()
 362                 {
 363                         int l = length - initialIndex;
 364                         byte[] outBuffer = new byte [l];
 365
 366                         if (internalBuffer != null)
 367                                 Buffer.BlockCopy (internalBuffer, initialIndex, outBuffer, 0, l);
 368                         return outBuffer;
 369                 }
 370
 371                 public override void Write (byte [] buffer, int offset, int count)
 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                         CheckIfClosedThrowDisposed ();
 387
 388                         // reordered to avoid possible integer overflow
 389                         if (position > length - count)
 390                                 Expand (position + count);
 391
 392                         Buffer.BlockCopy (buffer, offset, internalBuffer, position, count);
 393                         position += count;
 394                         if (position >= length)
 395                                 length = position;
 396                 }
 397
 398                 public override void WriteByte (byte value)
 399                 {
 400                         CheckIfClosedThrowDisposed ();
 401                         if (!canWrite)
 402                                 throw new NotSupportedException ("Cannot write to this stream.");
 403
 404                         if (position >= length) {
 405                                 Expand (position + 1);
 406                                 length = position + 1;
 407                         }
 408
 409                         internalBuffer [position++] = value;
 410                 }
 411
 412                 public virtual void WriteTo (Stream stream)
 413                 {
 414                         CheckIfClosedThrowDisposed ();
 415
 416                         if (stream == null)
 417                                 throw new ArgumentNullException ("stream");
 418
 419                         stream.Write (internalBuffer, initialIndex, length - initialIndex);
 420                 }
 421
 422 #if NET_4_0
 423                 protected override void ObjectInvariant ()
 424                 {
 425                 }
 426 #endif
 427         }
 428 }