Umbraco-CMS/src/Umbraco.Core/IO/IFileSystemExtensions.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Umbraco.Core.IO
{
    public static class IFileSystemExtensions
    {
        internal static long GetSize(this IFileSystem fs, string path)
        {
            var s = fs.OpenFile(path);
            var size = s.Length;
            s.Close();

            return size;
        }

        internal static void CopyFile(this IFileSystem fs, string path, string newPath)
        {
            fs.AddFile(newPath, fs.OpenFile(path));
        }
    }
}