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