mcs/class/corlib/System.Runtime.InteropServices/GCHandle.cs

   1 //
   2 // System.Runtime.InteropServices/GCHandle.cs
   3 //
   4 // Authors:
   5 //   Ajay kumar Dwivedi (adwiv@yahoo.com) ??
   6 //   Paolo Molaro (lupus@ximian.com)
   7 //
   8
   9 //
  10 // Copyright (C) 2004 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.Runtime.CompilerServices;
  34 using System.Runtime.InteropServices;
  35
  36 namespace System.Runtime.InteropServices
  37 {
  38
  39 #if NET_2_0
  40         [ComVisible(true)]
  41 #endif
  42         [MonoTODO("Struct should be [StructLayout(LayoutKind.Sequential)] but will need to be reordered for that.")]
  43         public struct GCHandle
  44         {
  45                 // fields
  46                 private int handle;
  47
  48                 private GCHandle(IntPtr h)
  49                 {
  50                         handle = (int)h;
  51                 }
  52
  53                 // Constructors
  54                 private GCHandle(object obj)
  55                         : this(obj, GCHandleType.Normal)
  56                 {}
  57
  58                 private GCHandle(object value, GCHandleType type)
  59                 {
  60                         handle = GetTargetHandle (value, 0, type);
  61                 }
  62
  63                 // Properties
  64
  65                 public bool IsAllocated
  66                 {
  67                         get
  68                         {
  69                                 return (handle != 0);
  70                         }
  71                 }
  72
  73                 public object Target
  74                 {
  75                         get
  76                         {
  77                                 return GetTarget (handle);
  78                         }
  79                         set
  80                         {
  81                                 handle = GetTargetHandle (value, handle, (GCHandleType)(-1));
  82                         }
  83                 }
  84
  85                 // Methods
  86                 public IntPtr AddrOfPinnedObject()
  87                 {
  88                         IntPtr res = GetAddrOfPinnedObject(handle);
  89                         if (res == IntPtr.Zero)
  90                                 throw new InvalidOperationException("The handle is not of Pinned type");
  91                         if (res == (IntPtr)(-1))
  92                                 throw new ArgumentException ("Object contains non-primitive or non-blittable data.");
  93                         return res;
  94                 }
  95
  96                 public static System.Runtime.InteropServices.GCHandle Alloc(object value)
  97                 {
  98                         return new GCHandle (value);
  99                 }
 100
 101                 public static System.Runtime.InteropServices.GCHandle Alloc(object value, GCHandleType type)
 102                 {
 103                         return new GCHandle (value,type);
 104                 }
 105
 106                 public void Free()
 107                 {
 108                         FreeHandle(handle);
 109                         handle = 0;
 110                 }
 111
 112                 public static explicit operator IntPtr (GCHandle value)
 113                 {
 114                         return (IntPtr) value.handle;
 115                 }
 116
 117                 public static explicit operator GCHandle(IntPtr value)
 118                 {
 119                         if (value == IntPtr.Zero)
 120                                 throw new ArgumentException ("GCHandle value cannot be zero");
 121                         if (!CheckCurrentDomain ((int)value))
 122                                 throw new ArgumentException ("GCHandle value belongs to a different domain");
 123                         return new GCHandle (value);
 124                 }
 125
 126                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 127                 private extern static bool CheckCurrentDomain (int handle);
 128
 129                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 130                 private extern static object GetTarget(int handle);
 131
 132                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 133                 private extern static int GetTargetHandle(object obj, int handle, GCHandleType type);
 134
 135                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 136                 private extern static void FreeHandle(int handle);
 137
 138                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 139                 private extern static IntPtr GetAddrOfPinnedObject(int handle);
 140
 141 #if NET_2_0
 142                 public static bool operator ==(GCHandle a, GCHandle b)
 143                 {
 144                         return a.Equals(b);
 145                 }
 146
 147                 public static bool operator !=(GCHandle a, GCHandle b)
 148                 {
 149                         return (!(a.Equals(b)));
 150                 }
 151
 152                 public override bool Equals(object o)
 153                 {
 154                         if (o == null || !(o is GCHandle))
 155                                 return false;
 156
 157                         return (handle == ((GCHandle)o).handle);
 158                 }
 159
 160                 public override int GetHashCode()
 161                 {
 162                         return handle.GetHashCode ();
 163                 }
 164
 165                 public static GCHandle FromIntPtr (IntPtr value)
 166                 {
 167                         return (GCHandle)value;
 168                 }
 169
 170                 public static IntPtr ToIntPtr (GCHandle value)
 171                 {
 172                         return (IntPtr)value;
 173                 }
 174 #endif
 175         }
 176 }
 177