System.Data.SqlClient.SqlStream.ReadBytes C# (CSharp) Method

        private int ReadBytes(byte[] buffer, int offset, int count)
        {
            bool gotData = true;
            int intCount = 0;
            int cb = 0;

            if (_reader.IsClosed || _endOfColumn)
            {
                return 0;
            }
            try
            {
                while (count > 0)
                {
                    // if no bytes were read, get the next row
                    if (_advanceReader && (0 == _bytesCol))
                    {
                        gotData = false;

                        if (_readFirstRow && !_processAllRows)
                        {
                            // for XML column, stop processing after the first row
                            // no op here - reader is closed after the end of this loop
                        }
                        else if (AdvanceToNextRow(_reader))
                        {
                            _readFirstRow = true;

                            if (_reader.IsDBNull(_columnOrdinal))
                            {
                                // Handle row with DBNULL as empty data
                                // for XML column, processing is stopped on the next loop since _readFirstRow is true
                                continue;
                            }

                            // the value is not null, read it
                            gotData = true;
                        }
                        // else AdvanceToNextRow has returned false - no more rows or result sets remained, stop processing
                    }

                    if (gotData)
                    {
                        cb = (int)_reader.GetBytesInternal(_columnOrdinal, _bytesCol, buffer, offset, count);

                        if (cb < count)
                        {
                            _bytesCol = 0;
                            gotData = false;
                            if (!_advanceReader)
                            {
                                _endOfColumn = true;
                            }
                        }
                        else
                        {
                            Debug.Assert(cb == count);
                            _bytesCol += cb;
                        }

                        // we are guaranteed that cb is < Int32.Max since we always pass in count which is of type Int32 to
                        // our getbytes interface
                        count -= (int)cb;
                        offset += (int)cb;
                        intCount += (int)cb;
                    }
                    else
                    {
                        break; // no more data available, we are done
                    }
                }
                if (!gotData && _advanceReader)
                {
                    _reader.Close();    // Need to close the reader if we are done reading
                }
            }
            catch (Exception e)
            {
                if (_advanceReader && ADP.IsCatchableExceptionType(e))
                {
                    _reader.Close();
                }
                throw;
            }

            return intCount;
        }