Adding Contents of a .DAT File to DataGridView

[StructLayout(LayoutKind.Sequential, Pack = 1, CharSet = CharSet.Ansi)]
    struct file_record
    {

        public char Exch;
        public int ExchCode;
        public byte NameLength;
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 12)]
        public char[] ScripName;

    }


    private void button1_Click(object sender, EventArgs e)
    {

        OpenFileDialog ofd = new OpenFileDialog();
        string path = "";
        ofd.FileName = "";
        ofd.ShowDialog();
        path = ofd.FileName;

        if (string.IsNullOrEmpty(ofd.FileName))
        return;
        FileStream fs = new FileStream(path, FileMode.OpenOrCreate, FileAccess.ReadWrite);
        BinaryReader br = new BinaryReader(fs);

        int value = Marshal.SizeOf(typeof(file_record));


        var len = fs.Length;
        var num_records = len / value;
        file_record[] Bse = new file_record[num_records];
        Byte[] buffer = new Byte[Marshal.SizeOf(typeof(file_record))];
        for (int i = 0; i < num_records; i++)
        {
            fs.Read(buffer, 0, value);
            GCHandle handle = GCHandle.Alloc(buffer, GCHandleType.Pinned);
            Bse[i] = (file_record)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(file_record));
            string abc = new string(Bse[i].ScripName);
            string str2 = abc.Substring(0, Bse[i].NameLength);
            listBox1.Items.Add(Bse[i].ExchCode + " " + str2);
            handle.Free();

        }

    }