/// <summary>
/// Method to open an existing storage from stream
/// </summary>
/// <param name="stream">Already opened stream with zip contents</param>
/// <param name="access">File access mode for stream operations</param>
/// <returns>A valid ZipStorer object</returns>
public static ZipStorer open(Stream stream, FileAccess access)
{
if (!stream.CanSeek && access != FileAccess.Read)
throw new InvalidOperationException("Stream cannot seek");
ZipStorer zip = new ZipStorer();
//zip.FileName = _filename;
zip.zipFileStream = stream;
zip.access = access;
if (zip.readFileInfo())
return zip;
throw new System.IO.InvalidDataException();
}