FieldOffsetAttribute.cs

using System.Reflection;
using System.Security;

namespace System.Runtime.InteropServices
{
    [AttributeUsage(AttributeTargets.Field, Inherited = false)]
    [ComVisible(true)]
    [__DynamicallyInvokable]
    public sealed class FieldOffsetAttribute : Attribute
    {
        internal int _val;

        [__DynamicallyInvokable]
        public int Value
        {
            [__DynamicallyInvokable]
            get
            {
                return _val;
            }
        }

        [SecurityCritical]
        internal static Attribute GetCustomAttribute(RuntimeFieldInfo field)
        {
            if (field.DeclaringType != null && field.GetRuntimeModule().MetadataImport.GetFieldOffset(field.DeclaringType.MetadataToken, field.MetadataToken, out int offset))
            {
                return new FieldOffsetAttribute(offset);
            }
            return null;
        }

        [SecurityCritical]
        internal static bool IsDefined(RuntimeFieldInfo field)
        {
            return GetCustomAttribute(field) != null;
        }

        [__DynamicallyInvokable]
        public FieldOffsetAttribute(int offset)
        {
            _val = offset;
        }
    }
}