public Stream GetFileStream(File file, long offset) { var fileToDownload = ProviderInfo.GetFileById(file.ID); if (fileToDownload == null) { throw new ArgumentNullException("file", Web.Files.Resources.FilesCommonResource.ErrorMassage_FileNotFound); } var fileStream = ProviderInfo.GetFileStream(fileToDownload.ServerRelativeUrl, (int)offset); return(fileStream); }