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

   1 //
   2 // System.IO.MemoryStream
   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 #if NET_2_0
  43         [ComVisible (true)]
  44 #endif
  45         [MonoTODO ("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
  58                 public MemoryStream () : this (0)
  59                 {
  60                 }
  61
  62                 public MemoryStream (int capacity)
  63                 {
  64                         if (capacity < 0)
  65                                 throw new ArgumentOutOfRangeException ("capacity");
  66
  67                         canWrite = true;
  68
  69                         this.capacity = capacity;
  70                         internalBuffer = new byte [capacity];
  71
  72                         expandable = true;
  73                         allowGetBuffer = true;
  74                 }
  75
  76                 public MemoryStream (byte [] buffer)
  77                 {
  78                         if (buffer == null)
  79                                 throw new ArgumentNullException ("buffer");
  80
  81                         InternalConstructor (buffer, 0, buffer.Length, true, false);
  82                 }
  83
  84                 public MemoryStream (byte [] buffer, bool writeable)
  85                 {
  86                         if (buffer == null)
  87                                 throw new ArgumentNullException ("buffer");
  88
  89                         InternalConstructor (buffer, 0, buffer.Length, writeable, false);
  90                 }
  91
  92                 public MemoryStream (byte [] buffer, int index, int count)
  93                 {
  94                         InternalConstructor (buffer, index, count, true, false);
  95                 }
  96
  97                 public MemoryStream (byte [] buffer, int index, int count, bool writeable)
  98                 {
  99                         InternalConstructor (buffer, index, count, writeable, false);
 100                 }
 101
 102                 public MemoryStream (byte [] buffer, int index, int count, bool writeable, bool publicallyVisible)
 103                 {
 104                         InternalConstructor (buffer, index, count, writeable, publicallyVisible);
 105                 }
 106
 107                 void InternalConstructor (byte [] buffer, int index, int count, bool writeable, bool publicallyVisible)
 108                 {
 109                         if (buffer == null)
 110                                 throw new ArgumentNullException ("buffer");
 111
 112                         if (index < 0 || count < 0)
 113                                 throw new ArgumentOutOfRangeException ("index or count is less than 0.");
 114
 115                         if (buffer.Length - index < count)
 116                                 throw new ArgumentException ("index+count",
 117                                                              "The size of the buffer is less than index + count.");
 118
 119                         canWrite = writeable;
 120
 121                         internalBuffer = buffer;
 122                         capacity = count + index;
 123                         length = capacity;
 124                         position = index;
 125                         initialIndex = index;
 126
 127                         allowGetBuffer = publicallyVisible;
 128                         expandable = false;
 129                 }
 130
 131                 void CheckIfClosedThrowDisposed ()
 132                 {
 133                         if (streamClosed)
 134                                 throw new ObjectDisposedException ("MemoryStream");
 135                 }
 136
 137                 public override bool CanRead {
 138                         get { return !streamClosed; }
 139                 }
 140
 141                 public override bool CanSeek {
 142                         get { return !streamClosed; }
 143                 }
 144
 145                 public override bool CanWrite {
 146                         get { return (!streamClosed && canWrite); }
 147                 }
 148
 149                 public virtual int Capacity {
 150                         get {
 151                                 CheckIfClosedThrowDisposed ();
 152                                 return capacity - initialIndex;
 153                         }
 154
 155                         set {
 156                                 CheckIfClosedThrowDisposed ();
 157                                 if (value == capacity)
 158                                         return; // LAMENESS: see MemoryStreamTest.ConstructorFive
 159
 160                                 if (!expandable)
 161                                         throw new NotSupportedException ("Cannot expand this MemoryStream");
 162
 163                                 if (value < 0 || value < length)
 164                                         throw new ArgumentOutOfRangeException ("value",
 165                                         "New capacity cannot be negative or less than the current capacity " + value + " " + capacity);
 166
 167                                 byte [] newBuffer = null;
 168                                 if (value != 0) {
 169                                         newBuffer = new byte [value];
 170                                         Buffer.BlockCopy (internalBuffer, 0, newBuffer, 0, length);
 171                                 }
 172
 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 #if NET_2_0
 213                 protected override void Dispose (bool disposing)
 214 #else
 215                 public override void Close ()
 216 #endif
 217                 {
 218                         streamClosed = true;
 219                         expandable = false;
 220                 }
 221
 222                 public override void Flush ()
 223                 {
 224                         // Do nothing
 225                 }
 226
 227                 public virtual byte [] GetBuffer ()
 228                 {
 229                         if (!allowGetBuffer)
 230                                 throw new UnauthorizedAccessException ();
 231
 232                         return internalBuffer;
 233                 }
 234
 235                 public override int Read ([In,Out] byte [] buffer, int offset, int count)
 236                 {
 237                         CheckIfClosedThrowDisposed ();
 238
 239                         if (buffer == null)
 240                                 throw new ArgumentNullException ("buffer");
 241
 242                         if (offset < 0 || count < 0)
 243                                 throw new ArgumentOutOfRangeException ("offset or count less than zero.");
 244
 245                         if (buffer.Length - offset < count )
 246                                 throw new ArgumentException ("offset+count",
 247                                                               "The size of the buffer is less than offset + count.");
 248
 249                         if (position >= length || count == 0)
 250                                 return 0;
 251
 252                         if (position > length - count)
 253                                 count = length - position;
 254
 255                         Buffer.BlockCopy (internalBuffer, position, buffer, offset, count);
 256                         position += count;
 257                         return count;
 258                 }
 259
 260                 public override int ReadByte ()
 261                 {
 262                         CheckIfClosedThrowDisposed ();
 263                         if (position >= length)
 264                                 return -1;
 265
 266                         return internalBuffer [position++];
 267                 }
 268
 269                 public override long Seek (long offset, SeekOrigin loc)
 270                 {
 271                         CheckIfClosedThrowDisposed ();
 272
 273                         // It's funny that they don't throw this exception for < Int32.MinValue
 274                         if (offset > (long) Int32.MaxValue)
 275                                 throw new ArgumentOutOfRangeException ("Offset out of range. " + offset);
 276
 277                         int refPoint;
 278                         switch (loc) {
 279                         case SeekOrigin.Begin:
 280                                 if (offset < 0)
 281                                         throw new IOException ("Attempted to seek before start of MemoryStream.");
 282                                 refPoint = initialIndex;
 283                                 break;
 284                         case SeekOrigin.Current:
 285                                 refPoint = position;
 286                                 break;
 287                         case SeekOrigin.End:
 288                                 refPoint = length;
 289                                 break;
 290                         default:
 291                                 throw new ArgumentException ("loc", "Invalid SeekOrigin");
 292                         }
 293
 294                         // LAMESPEC: My goodness, how may LAMESPECs are there in this
 295                         // class! :)  In the spec for the Position property it's stated
 296                         // "The position must not be more than one byte beyond the end of the stream."
 297                         // In the spec for seek it says "Seeking to any location beyond the length of the
 298                         // stream is supported."  That's a contradiction i'd say.
 299                         // I guess seek can go anywhere but if you use position it may get moved back.
 300
 301                         refPoint += (int) offset;
 302                         if (refPoint < initialIndex)
 303                                 throw new IOException ("Attempted to seek before start of MemoryStream.");
 304
 305                         position = refPoint;
 306                         return position;
 307                 }
 308
 309                 int CalculateNewCapacity (int minimum)
 310                 {
 311                         if (minimum < 256)
 312                                 minimum = 256; // See GetBufferTwo test
 313
 314                         if (minimum < capacity * 2)
 315                                 minimum = capacity * 2;
 316
 317                         return minimum;
 318                 }
 319
 320                 public override void SetLength (long value)
 321                 {
 322                         if (!expandable && value > capacity)
 323                                 throw new NotSupportedException ("Expanding this MemoryStream is not supported");
 324
 325                         CheckIfClosedThrowDisposed ();
 326
 327                         if (!canWrite) {
 328                                 throw new NotSupportedException (Locale.GetText
 329                                         ("Cannot write to this MemoryStream"));
 330                         }
 331
 332                         // LAMESPEC: AGAIN! It says to throw this exception if value is
 333                         // greater than "the maximum length of the MemoryStream".  I haven't
 334                         // seen anywhere mention what the maximum length of a MemoryStream is and
 335                         // since we're this far this memory stream is expandable.
 336                         if (value < 0 || (value + initialIndex) > (long) Int32.MaxValue)
 337                                 throw new ArgumentOutOfRangeException ();
 338
 339                         int newSize = (int) value + initialIndex;
 340                         if (newSize > capacity)
 341                                 Capacity = CalculateNewCapacity (newSize);
 342                         else if (newSize < length)
 343                                 // zeroize present data (so we don't get it
 344                                 // back if we expand the stream using Seek)
 345                                 Array.Clear (internalBuffer, newSize, length - newSize);
 346
 347                         length = newSize;
 348                         if (position > length)
 349                                 position = length;
 350                 }
 351
 352                 public virtual byte [] ToArray ()
 353                 {
 354                         int l = length - initialIndex;
 355                         byte[] outBuffer = new byte [l];
 356
 357                         if (internalBuffer != null)
 358                                 Buffer.BlockCopy (internalBuffer, initialIndex, outBuffer, 0, l);
 359                         return outBuffer;
 360                 }
 361
 362                 public override void Write (byte [] buffer, int offset, int count)
 363                 {
 364                         CheckIfClosedThrowDisposed ();
 365
 366                         if (!canWrite)
 367                                 throw new NotSupportedException ("Cannot write to this stream.");
 368
 369                         if (buffer == null)
 370                                 throw new ArgumentNullException ("buffer");
 371
 372                         if (offset < 0 || count < 0)
 373                                 throw new ArgumentOutOfRangeException ();
 374
 375                         if (buffer.Length - offset < count)
 376                                 throw new ArgumentException ("offset+count",
 377                                                              "The size of the buffer is less than offset + count.");
 378
 379                         // reordered to avoid possible integer overflow
 380                         if (position > capacity - count)
 381                                 Capacity = CalculateNewCapacity (position + count);
 382
 383                         Buffer.BlockCopy (buffer, offset, internalBuffer, position, count);
 384                         position += count;
 385                         if (position >= length)
 386                                 length = position;
 387                 }
 388
 389                 public override void WriteByte (byte value)
 390                 {
 391                         CheckIfClosedThrowDisposed ();
 392                         if (!canWrite)
 393                                 throw new NotSupportedException ("Cannot write to this stream.");
 394
 395                         if (position >= capacity)
 396                                 Capacity = CalculateNewCapacity (position + 1);
 397
 398                         if (position >= length)
 399                                 length = position + 1;
 400
 401                         internalBuffer [position++] = value;
 402                 }
 403
 404                 public virtual void WriteTo (Stream stream)
 405                 {
 406                         CheckIfClosedThrowDisposed ();
 407
 408                         if (stream == null)
 409                                 throw new ArgumentNullException ("stream");
 410
 411                         stream.Write (internalBuffer, initialIndex, length - initialIndex);
 412                 }
 413         }
 414 }