Am I a prick or what?

am_I_a_prick.cs

class FileStream
    : System.IO.FileStream
{    
    protected long this[string key]
    {
        get {
            this.Position = 0;

            int c, p = 0;
            for (; ; )
            {
                c = this.ReadByte();
                if (c < 0)
                {

                    this.Write(Encoding.ASCII.GetBytes(key), 0, key.Length);
                    this.WriteByte((byte)'\0');
                    break;
                }

                if (p == key.Length && c == '\0')
                {
                    break;
                }

                if (p == key.Length || c != key[p])
                {
                    p = 0;
                    this.Position -= c == '\0' ? 0 : p - 1;
                    continue;
                }

                p++;
            }

            return this.Position - p;
        }
    }
}