Renci.SshNet.SftpClient.InternalDownloadFile C# (CSharp) Method

        private void InternalDownloadFile(string path, Stream output, SftpDownloadAsyncResult asyncResult, Action<ulong> downloadCallback)
        {
            if (output == null)
                throw new ArgumentNullException("output");

            if (path.IsNullOrWhiteSpace())
                throw new ArgumentException("path");

            if (_sftpSession == null)
                throw new SshConnectionException("Client not connected.");

            var fullPath = _sftpSession.GetCanonicalPath(path);

            var handle = _sftpSession.RequestOpen(fullPath, Flags.Read);

            ulong offset = 0;

            var optimalReadLength = _sftpSession.CalculateOptimalReadLength(_bufferSize);

            var data = _sftpSession.RequestRead(handle, offset, optimalReadLength);

            //  Read data while available
            while (data.Length > 0)
            {
                //  Cancel download
                if (asyncResult != null && asyncResult.IsDownloadCanceled)
                    break;

                output.Write(data, 0, data.Length);

                output.Flush();

                offset += (ulong)data.Length;

                //  Call callback to report number of bytes read
                if (downloadCallback != null)
                {
                    // copy offset to ensure it's not modified between now and execution of callback
                    var downloadOffset = offset;

                    //  Execute callback on different thread
                    ThreadAbstraction.ExecuteThread(() => { downloadCallback(downloadOffset); });
                }

                data = _sftpSession.RequestRead(handle, offset, optimalReadLength);
            }

            _sftpSession.RequestClose(handle);
        }