private static unsafe void FreePropVariant(IntPtr buffer, int valueOffset)
{
// two contigous 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 == 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));
RuntimeHelpers.PrepareConstrainedRegions();
try
{ }
finally
{
// always clear the first structure
Interop.Ole32.PropVariantClear(currentHandle);
if (different)
{
// second structure different from the first
Interop.Ole32.PropVariantClear(originalHandle);
}
else
{
// second structure same as the first, just clear the field
SafeNativeMethods.ZeroMemory(originalHandle, sizeof(PROPVARIANT));
}
}
}
private static void FreeVariant(IntPtr buffer, int valueOffset)
{
IntPtr ptr2 = ADP.IntPtrOffset(buffer, valueOffset);
IntPtr ptr = ADP.IntPtrOffset(buffer, valueOffset + ODB.SizeOf_Variant);
bool flag = NativeOledbWrapper.MemoryCompare(ptr2, ptr, ODB.SizeOf_Variant);
RuntimeHelpers.PrepareConstrainedRegions();
try
{
}
finally
{
SafeNativeMethods.VariantClear(ptr2);
if (flag)
{
SafeNativeMethods.VariantClear(ptr);
}
else
{
SafeNativeMethods.ZeroMemory(ptr, (IntPtr)ODB.SizeOf_Variant);
}
}
}
