class/System.Windows/System.IO/SimpleUnmanagedMemoryStream.cs

   1 //
   2 // System.IO.SimpleUnmanagedMemoryStream.cs
   3 //
   4 // Copyright (C) 2006 Sridhar Kulkarni, All Rights Reserved
   5 //
   6 // Authors:
   7 //      Sridhar Kulkarni (sridharkulkarni@gmail.com)
   8 //      Gert Driesen (drieseng@users.sourceforge.net)
   9 //
  10 // Copyright (C) 2005-2006 Novell, Inc (http://www.novell.com)
  11 //
  12 // Permission is hereby granted, free of charge, to any person obtaining
  13 // a copy of this software and associated documentation files (the
  14 // "Software"), to deal in the Software without restriction, including
  15 // without limitation the rights to use, copy, modify, merge, publish,
  16 // distribute, sublicense, and/or sell copies of the Software, and to
  17 // permit persons to whom the Software is furnished to do so, subject to
  18 // the following conditions:
  19 //
  20 // The above copyright notice and this permission notice shall be
  21 // included in all copies or substantial portions of the Software.
  22 //
  23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  27 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  28 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  29 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  30 //
  31
  32 using System;
  33 using System.IO;
  34 using System.Runtime.InteropServices;
  35
  36 namespace System.IO
  37 {
  38         internal class SimpleUnmanagedMemoryStream : Stream
  39         {
  40                 long length;
  41                 long capacity;
  42                 IntPtr initial_pointer;
  43                 long initial_position;
  44                 long current_position;
  45
  46                 protected SimpleUnmanagedMemoryStream()
  47                 {
  48                         initial_position = 0;
  49                         current_position = initial_position;
  50                 }
  51
  52                 public unsafe SimpleUnmanagedMemoryStream (byte *pointer, long length)
  53                 {
  54                         if (pointer == null)
  55                                 throw new ArgumentNullException("pointer");
  56                         if (length < 0)
  57                                 throw new ArgumentOutOfRangeException("length", "Non-negative number required.");
  58                         this.length = length;
  59                         capacity = length;
  60                         initial_position = 0;
  61                         current_position = initial_position;
  62                         initial_pointer = new IntPtr((void*)pointer);
  63                 }
  64
  65                 public override bool CanRead {
  66                         get {
  67                                 return true;
  68                         }
  69                 }
  70
  71                 public override bool CanSeek {
  72                         get {
  73                                 return true;
  74                         }
  75                 }
  76
  77                 public override bool CanWrite {
  78                         get {
  79                                 return false;
  80                         }
  81                 }
  82
  83                 public override long Length {
  84                         get {
  85                                 return (length);
  86                         }
  87                 }
  88                 public override long Position {
  89                         get {
  90                                 return (current_position);
  91                         }
  92                         set {
  93                                 if (value < 0)
  94                                         throw new ArgumentOutOfRangeException("value", "Non-negative number required.");
  95                                 if (value > (long)Int32.MaxValue)
  96                                         throw new ArgumentOutOfRangeException("value", "The position is larger than Int32.MaxValue.");
  97                                 current_position = value;
  98                         }
  99                 }
 100
 101                 public override int Read ([InAttribute] [OutAttribute] byte[] buffer, int offset, int count)
 102                  {
 103                          if (buffer == null)
 104                                  throw new ArgumentNullException("buffer");
 105                          if (offset < 0)
 106                                  throw new ArgumentOutOfRangeException("offset", "Non-negative number required.");
 107                          if (count < 0)
 108                                  throw new ArgumentOutOfRangeException("count", "Non-negative number required.");
 109                          if ((buffer.Length - offset) < count)
 110                                  throw new ArgumentException("The length of the buffer array minus the offset parameter is less than the count parameter");
 111
 112                          if (current_position >= length)
 113                                  return (0);
 114                          else {
 115                                  int progress = current_position + count < length ? count : (int) (length - current_position);
 116                                  for (int i = 0; i < progress; i++)
 117                                          buffer [offset + i] = Marshal.ReadByte (initial_pointer, (int) current_position++);
 118                                  return progress;
 119                          }
 120                  }
 121
 122                 public override int ReadByte ()
 123                 {
 124                         if (current_position >= length)
 125                                 return (-1);
 126                         return (int) Marshal.ReadByte(initial_pointer, (int) current_position++);
 127                 }
 128
 129                 public override long Seek (long offset, SeekOrigin loc)
 130                 {
 131                         long refpoint;
 132                         switch(loc) {
 133                         case SeekOrigin.Begin:
 134                                 if (offset < 0)
 135                                         throw new IOException("An attempt was made to seek before the beginning of the stream");
 136                                 refpoint = initial_position;
 137                                 break;
 138                         case SeekOrigin.Current:
 139                                 refpoint = current_position;
 140                                 break;
 141                         case SeekOrigin.End:
 142                                 refpoint = length;
 143                                 break;
 144                         default:
 145                                 throw new ArgumentException("Invalid SeekOrigin option");
 146                         }
 147                         refpoint += (int)offset;
 148                         if (refpoint < initial_position)
 149                                 throw new IOException("An attempt was made to seek before the beginning of the stream");
 150                         current_position = refpoint;
 151                         return(current_position);
 152                 }
 153
 154                 public override void SetLength (long value)
 155                 {
 156                         if (value < 0)
 157                                 throw new ArgumentOutOfRangeException("length", "Non-negative number required.");
 158                         if (value > capacity)
 159                                 throw new IOException ("Unable to expand length of this stream beyond its capacity.");
 160                         length = value;
 161                         if (length < current_position)
 162                                 current_position = length;
 163                 }
 164
 165                 public override void Flush ()
 166                 {
 167                 }
 168
 169                 protected override void Dispose (bool disposing)
 170                 {
 171                 }
 172
 173                 public override void Write (byte[] buffer, int offset, int count)
 174                 {
 175                         throw new NotSupportedException ("Stream does not support writing.");
 176                 }
 177
 178                 public override void WriteByte (byte value)
 179                 {
 180                          throw new NotSupportedException("Stream does not support writing.");
 181                 }
 182         }
 183 }
 184