System.Net.WebClient.DownloadBitsState.SetResponse C# (CSharp) Method

            internal int SetResponse(WebResponse response) {
                ContentLength = response.ContentLength;

                if (ContentLength == -1 || ContentLength > DefaultDownloadBufferLength) {
                    Length = DefaultDownloadBufferLength; // Read buffer length
                } else {
                    Length = ContentLength; // Read buffer length
                }
                
                // If we are not writing to a stream, we are accumulating in memory
                if (WriteStream == null) {
                    // We are putting a cap on the size we will accumulate in memory
                    if (ContentLength > Int32.MaxValue)
                    {
                        throw new WebException(SR.GetString(SR.net_webstatus_MessageLengthLimitExceeded), WebExceptionStatus.MessageLengthLimitExceeded);
                    }
                    SgBuffers = new ScatterGatherBuffers(Length); // Write buffer
                }

                InnerBuffer = new byte[(int)Length];

                ReadStream = response.GetResponseStream();
                if (Async && response.ContentLength >= 0)
                    Progress.TotalBytesToReceive = response.ContentLength;
                
                if (Async) {
                    if (ReadStream == null || ReadStream == Stream.Null)
                        DownloadBitsReadCallbackState(this, null);
                    else
                        ReadStream.BeginRead(InnerBuffer, Offset, (int)Length-Offset, new AsyncCallback(DownloadBitsReadCallback), this);
                } else {
                    if (ReadStream == null || ReadStream == Stream.Null)
                        return 0;
                    else
                        return ReadStream.Read(InnerBuffer, Offset, (int)Length-Offset);
                }
                return -1;
            }