public Stream OpenRelative(string path, FileMode mode, FileAccess access, FileShare share)
{
if (string.IsNullOrEmpty(path))
throw new ArgumentNullException("path");
if (path[0] != Path.DirectorySeparatorChar && path[0] != Path.AltDirectorySeparatorChar)
path = Path.DirectorySeparatorChar + path;
path = rootPath + path;
return FileManager.Open(path, mode, access, share);
}