Use System.Runtime.InteropServices.Marshalling.ComVariant instead of custom VARIANT types in libraries (#123060)

Co-authored-by: Aaron R Robinson <[email protected]>

Author: jkoritzinsky

src/libraries/Common/src/Interop/Windows/OleAut32/Interop.VariantInit.cs

@@ -188,8 +188,8 @@ internal int MaxLen
                 {
                     case (NativeDBType.BSTR):  // ADP.PtrSize
                     case (NativeDBType.HCHAPTER): // ADP.PtrSize
-                    case (NativeDBType.PROPVARIANT): // sizeof(PROPVARIANT)
-                    case (NativeDBType.VARIANT): // 16 or 24 (8 + ADP.PtrSize *2)
+                    case (NativeDBType.PROPVARIANT): // sizeof(ComVariant)
+                    case (NativeDBType.VARIANT): // sizeof(ComVariant)
                     case (NativeDBType.BYREF | NativeDBType.BYTES): // ADP.PtrSize
                     case (NativeDBType.BYREF | NativeDBType.WSTR): // ADP.PtrSize
                                                                    // allocate extra space to cache original value for disposal

src/libraries/System.Data.OleDb/src/DbBindings.cs

@@ -144,7 +144,7 @@ protected override bool ReleaseHandle()
                         IntPtr vptr = ADP.IntPtrOffset(rgProperties, ODB.OffsetOf_tagDBPROP_Value);
                         for (int k = 0; k < cProperties; ++k, vptr = ADP.IntPtrOffset(vptr, ODB.SizeOf_tagDBPROP))
                         {
-                            Interop.OleAut32.VariantClear(vptr);
+                            Interop.Ole32.PropVariantClear(vptr);
                         }
                         Interop.Ole32.CoTaskMemFree(rgProperties);
                     }

src/libraries/System.Data.OleDb/src/DbPropSet.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Data.Common;
+using System.Runtime.InteropServices.Marshalling;
 
 namespace System.Data.OleDb
 {
@@ -148,8 +149,7 @@ internal sealed class NativeDBType
         private static readonly NativeDBType D_LongVarBinary = new NativeDBType(0xff, -1, false, true, OleDbType.LongVarBinary, NativeDBType.BYTES, S_LONGVARBINARY, typeof(byte[]), NativeDBType.BYTES, DbType.Binary); // 19
         private static readonly NativeDBType D_LongVarChar = new NativeDBType(0xff, -1, false, true, OleDbType.LongVarChar, NativeDBType.STR, S_LONGVARCHAR, typeof(string), NativeDBType.WSTR/*STR*/, DbType.AnsiString); // 20 - (ansi pointer)
         private static readonly NativeDBType D_Numeric = new NativeDBType(28, 19, true, false, OleDbType.Numeric, NativeDBType.NUMERIC, S_NUMERIC, typeof(decimal), NativeDBType.NUMERIC, DbType.Decimal); // 21 - (tagDB_Numeric)
-        private static readonly unsafe NativeDBType D_PropVariant = new NativeDBType(0xff, sizeof(PROPVARIANT),
-                                                                                                             true, false, OleDbType.PropVariant, NativeDBType.PROPVARIANT, S_PROPVARIANT, typeof(object), NativeDBType.VARIANT, DbType.Object); // 22
+        private static readonly unsafe NativeDBType D_PropVariant = new NativeDBType(0xff, sizeof(ComVariant), true, false, OleDbType.PropVariant, NativeDBType.PROPVARIANT, S_PROPVARIANT, typeof(object), NativeDBType.VARIANT, DbType.Object); // 22
         private static readonly NativeDBType D_Single = new NativeDBType(7, 4, true, false, OleDbType.Single, NativeDBType.R4, S_R4, typeof(float), NativeDBType.R4, DbType.Single); // 23 - single
         private static readonly NativeDBType D_Double = new NativeDBType(15, 8, true, false, OleDbType.Double, NativeDBType.R8, S_R8, typeof(double), NativeDBType.R8, DbType.Double); // 24 - double
         private static readonly NativeDBType D_UnsignedTinyInt = new NativeDBType(3, 1, true, false, OleDbType.UnsignedTinyInt, NativeDBType.UI1, S_UI1, typeof(byte), NativeDBType.UI1, DbType.Byte); // 25 - byte7

src/libraries/System.Data.OleDb/src/OleDb_Enum.cs

@@ -5,7 +5,9 @@
 using System.Data.Common;
 using System.Diagnostics;
 using System.Globalization;
+using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+using System.Runtime.InteropServices.Marshalling;
 using System.Text;
 
 namespace System.Data.OleDb
@@ -569,7 +571,7 @@ internal static InvalidOperationException IDBInfoNotSupported()
         internal static readonly int SizeOf_tagDBPROPINFO = IsRunningOnX86 ? Marshal.SizeOf<tagDBPROPINFO_x86>() : Marshal.SizeOf<tagDBPROPINFO>();
         internal static readonly int SizeOf_tagDBPROPIDSET = Marshal.SizeOf<tagDBPROPIDSET>();
         internal static readonly int SizeOf_Guid = Marshal.SizeOf<Guid>();
-        internal static readonly int SizeOf_Variant = 8 + (2 * IntPtr.Size); // 16 on 32bit, 24 on 64bit
+        internal static readonly int SizeOf_Variant = Unsafe.SizeOf<ComVariant>();
 
         internal static readonly int OffsetOf_tagDBPROP_Status = IsRunningOnX86 ? Marshal.OffsetOf(typeof(tagDBPROP_x86), "dwStatus").ToInt32() : Marshal.OffsetOf(typeof(tagDBPROP), "dwStatus").ToInt32();
         internal static readonly int OffsetOf_tagDBPROP_Value = IsRunningOnX86 ? Marshal.OffsetOf(typeof(tagDBPROP_x86), "vValue").ToInt32() : Marshal.OffsetOf(typeof(tagDBPROP), "vValue").ToInt32();

src/libraries/System.Data.OleDb/src/OleDb_Util.cs

@@ -125,7 +125,7 @@ protected override bool ReleaseHandle()
                         for (int k = 0; k < infoCount; ++k)
                         {
                             IntPtr valuePtr = ADP.IntPtrOffset(infoPtr, (k * ODB.SizeOf_tagDBPROPINFO) + ODB.OffsetOf_tagDBPROPINFO_Value);
-                            Interop.OleAut32.VariantClear(valuePtr);
+                            Interop.Ole32.PropVariantClear(valuePtr);
                         }
                         Interop.Ole32.CoTaskMemFree(infoPtr); // was allocated by provider
                     }

src/libraries/System.Data.OleDb/src/PropertyInfoSet.cs

@@ -5,6 +5,7 @@
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+using System.Runtime.InteropServices.Marshalling;
 
 namespace System.Data.OleDb
 {
@@ -407,14 +408,11 @@ private unsafe void ResetValues(IntPtr buffer, object? iaccessor)
                         ValidateCheck(valueOffset, 2 * IntPtr.Size);
                         FreeCoTaskMem(buffer, valueOffset);
                         break;
+                    case NativeDBType.VARIANT:
                     case NativeDBType.PROPVARIANT:
-                        ValidateCheck(valueOffset, 2 * sizeof(PROPVARIANT));
+                        ValidateCheck(valueOffset, 2 * sizeof(ComVariant));
                         FreePropVariant(buffer, valueOffset);
                         break;
-                    case NativeDBType.VARIANT:
-                        ValidateCheck(valueOffset, 2 * ODB.SizeOf_Variant);
-                        FreeVariant(buffer, valueOffset);
-                        break;
                     case NativeDBType.BSTR:
                         ValidateCheck(valueOffset, 2 * IntPtr.Size);
                         FreeBstr(buffer, valueOffset);
@@ -533,48 +531,16 @@ private static void FreeCoTaskMem(IntPtr buffer, int valueOffset)
             }
         }
 
-        private static void FreeVariant(IntPtr buffer, int valueOffset)
-        {
-            // two contiguous VARIANT structures that need to be freed
-            // the second should only be freed if different from the first
-
-            Debug.Assert(0 == (ODB.SizeOf_Variant % 8), "unexpected VARIANT size mutiplier");
-            Debug.Assert(0 == valueOffset % 8, "unexpected unaligned ptr offset");
-
-            IntPtr currentHandle = ADP.IntPtrOffset(buffer, valueOffset);
-            IntPtr originalHandle = ADP.IntPtrOffset(buffer, valueOffset + ODB.SizeOf_Variant);
-            bool different = NativeOledbWrapper.MemoryCompare(currentHandle, originalHandle, ODB.SizeOf_Variant);
-
-            RuntimeHelpers.PrepareConstrainedRegions();
-            try
-            { }
-            finally
-            {
-                // always clear the first structure
-                Interop.OleAut32.VariantClear(currentHandle);
-                if (different)
-                {
-                    // second structure different from the first
-                    Interop.OleAut32.VariantClear(originalHandle);
-                }
-                else
-                {
-                    // second structure same as the first, just clear the field
-                    SafeNativeMethods.ZeroMemory(originalHandle, ODB.SizeOf_Variant);
-                }
-            }
-        }
-
         private static unsafe void FreePropVariant(IntPtr buffer, int valueOffset)
         {
             // two contiguous PROPVARIANT structures that need to be freed
             // the second should only be freed if different from the first
-            Debug.Assert(0 == (sizeof(PROPVARIANT) % 8), "unexpected PROPVARIANT size mutiplier");
+            Debug.Assert(0 == (sizeof(ComVariant) % 8), "unexpected PROPVARIANT size mutiplier");
             Debug.Assert(0 == valueOffset % 8, "unexpected unaligned ptr offset");
 
             IntPtr currentHandle = ADP.IntPtrOffset(buffer, valueOffset);
-            IntPtr originalHandle = ADP.IntPtrOffset(buffer, valueOffset + sizeof(PROPVARIANT));
-            bool different = NativeOledbWrapper.MemoryCompare(currentHandle, originalHandle, sizeof(PROPVARIANT));
+            IntPtr originalHandle = ADP.IntPtrOffset(buffer, valueOffset + sizeof(ComVariant));
+            bool different = NativeOledbWrapper.MemoryCompare(currentHandle, originalHandle, sizeof(ComVariant));
 
             RuntimeHelpers.PrepareConstrainedRegions();
             try
@@ -591,7 +557,7 @@ private static unsafe void FreePropVariant(IntPtr buffer, int valueOffset)
                 else
                 {
                     // second structure same as the first, just clear the field
-                    SafeNativeMethods.ZeroMemory(originalHandle, sizeof(PROPVARIANT));
+                    SafeNativeMethods.ZeroMemory(originalHandle, sizeof(ComVariant));
                 }
             }
         }