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, 2009 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.Threading;
  34 using System.Runtime.CompilerServices;
  35 using System.Runtime.InteropServices;
  36
  37 namespace System.Runtime.InteropServices
  38 {
  39
  40         [ComVisible(true)]
  41         [MonoTODO("Struct should be [StructLayout(LayoutKind.Sequential)] but will need to be reordered for that.")]
  42         public struct GCHandle
  43         {
  44                 // fields
  45                 private int handle;
  46
  47                 private GCHandle(IntPtr h)
  48                 {
  49                         handle = (int)h;
  50                 }
  51
  52                 // Constructors
  53                 private GCHandle(object obj)
  54                         : this(obj, GCHandleType.Normal)
  55                 {}
  56
  57                 internal GCHandle(object value, GCHandleType type)
  58                 {
  59                         // MS does not crash/throw on (most) invalid GCHandleType values (except -1)
  60                         if ((type < GCHandleType.Weak) || (type > GCHandleType.Pinned))
  61                                 type = GCHandleType.Normal;
  62                         handle = GetTargetHandle (value, 0, type);
  63                 }
  64
  65                 // Properties
  66
  67                 public bool IsAllocated
  68                 {
  69                         get
  70                         {
  71                                 return (handle != 0);
  72                         }
  73                 }
  74
  75                 public object Target
  76                 {
  77                         get
  78                         {
  79                                 if (!IsAllocated)
  80                                         throw new InvalidOperationException (Locale.GetText ("Handle is not allocated"));
  81                                 return GetTarget (handle);
  82                         }
  83                         set
  84                         {
  85                                 handle = GetTargetHandle (value, handle, (GCHandleType)(-1));
  86                         }
  87                 }
  88
  89                 // Methods
  90                 public IntPtr AddrOfPinnedObject()
  91                 {
  92                         IntPtr res = GetAddrOfPinnedObject(handle);
  93                         if (res == (IntPtr)(-1))
  94                                 throw new ArgumentException ("Object contains non-primitive or non-blittable data.");
  95                         if (res == (IntPtr)(-2))
  96                                 throw new InvalidOperationException("Handle is not pinned.");
  97                         return res;
  98                 }
  99
 100                 public static System.Runtime.InteropServices.GCHandle Alloc(object value)
 101                 {
 102                         return new GCHandle (value);
 103                 }
 104
 105                 public static System.Runtime.InteropServices.GCHandle Alloc(object value, GCHandleType type)
 106                 {
 107                         return new GCHandle (value,type);
 108                 }
 109
 110                 public void Free()
 111                 {
 112                         // Copy the handle instance member to a local variable. This is required to prevent
 113                         // race conditions releasing the handle.
 114                         int local_handle = handle;
 115
 116                         // Free the handle if it hasn't already been freed.
 117                         if (local_handle != 0 && Interlocked.CompareExchange (ref handle, 0, local_handle) == local_handle) {
 118                                 FreeHandle (local_handle);
 119                         }
 120                         else {
 121                                 throw new InvalidOperationException ("Handle is not initialized.");
 122                         }
 123                 }
 124
 125                 public static explicit operator IntPtr (GCHandle value)
 126                 {
 127                         return (IntPtr) value.handle;
 128                 }
 129
 130                 public static explicit operator GCHandle(IntPtr value)
 131                 {
 132                         if (value == IntPtr.Zero)
 133                                 throw new InvalidOperationException ("GCHandle value cannot be zero");
 134                         if (!CheckCurrentDomain ((int)value))
 135                                 throw new ArgumentException ("GCHandle value belongs to a different domain");
 136                         return new GCHandle (value);
 137                 }
 138
 139                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 140                 private extern static bool CheckCurrentDomain (int handle);
 141
 142                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 143                 private extern static object GetTarget(int handle);
 144
 145                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 146                 private extern static int GetTargetHandle(object obj, int handle, GCHandleType type);
 147
 148                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 149                 private extern static void FreeHandle(int handle);
 150
 151                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
 152                 private extern static IntPtr GetAddrOfPinnedObject(int handle);
 153
 154                 public static bool operator ==(GCHandle a, GCHandle b)
 155                 {
 156                         return a.handle == b.handle;
 157                 }
 158
 159                 public static bool operator !=(GCHandle a, GCHandle b)
 160                 {
 161                         return !(a == b);
 162                 }
 163
 164                 public override bool Equals(object o)
 165                 {
 166                         return o is GCHandle ? this == (GCHandle)o : false;
 167                 }
 168
 169                 public override int GetHashCode()
 170                 {
 171                         return handle.GetHashCode ();
 172                 }
 173
 174                 public static GCHandle FromIntPtr (IntPtr value)
 175                 {
 176                         return (GCHandle)value;
 177                 }
 178
 179                 public static IntPtr ToIntPtr (GCHandle value)
 180                 {
 181                         return (IntPtr)value;
 182                 }
 183         }
 184 }
 185