private final long transfer()

in core/src/main/java/org/apache/ftpserver/impl/IODataConnection.java [197:312]
86 lines of code
21 McCabe index (conditional complexity)

    private final long transfer(FtpSession session, boolean isWrite,
            final InputStream in, final OutputStream out, final int maxRate)
            throws IOException {
        long transferredSize = 0L;

        boolean isAscii = session.getDataType() == DataType.ASCII;
        long startTime = System.currentTimeMillis();
        byte[] buff = new byte[4096];

        BufferedInputStream bis = null;
        BufferedOutputStream bos = null;
        try {
            bis = IoUtils.getBufferedInputStream(in);

            bos = IoUtils.getBufferedOutputStream(out);

            DefaultFtpSession defaultFtpSession = null;
            if (session instanceof DefaultFtpSession) {
                defaultFtpSession = (DefaultFtpSession) session;
            }

            byte lastByte = 0;
            while (true) {

                // if current rate exceeds the max rate, sleep for 50ms
                // and again check the current transfer rate
                if (maxRate > 0) {

                    // prevent "divide by zero" exception
                    long interval = System.currentTimeMillis() - startTime;
                    if (interval == 0) {
                        interval = 1;
                    }

                    // check current rate
                    long currRate = (transferredSize * 1000L) / interval;
                    if (currRate > maxRate) {
                        try {
                            Thread.sleep(50);
                        } catch (InterruptedException ex) {
                            break;
                        }
                        continue;
                    }
                }

                // read data
                int count = bis.read(buff);

                if (count == -1) {
                    break;
                }

                // update MINA session
                if (defaultFtpSession != null) {
                    if (isWrite) {
                        defaultFtpSession.increaseWrittenDataBytes(count);
                    } else {
                        defaultFtpSession.increaseReadDataBytes(count);
                    }
                }

                // write data
                // if ascii, replace \n by \r\n
                if (isAscii) {
                    for (int i = 0; i < count; ++i) {
                        byte b = buff[i];
                        if(isWrite) {
                            if (b == '\n' && lastByte != '\r') {
                                bos.write('\r');
                            }
    
                            bos.write(b);
                        } else {
                            if(b == '\n') {
                                // for reads, we should always get \r\n
                                // so what we do here is to ignore \n bytes 
                                // and on \r dump the system local line ending.
                                // Some clients won't transform new lines into \r\n so we make sure we don't delete new lines
                                if (lastByte != '\r'){
                                    bos.write(EOL);
                                }
                            } else if(b == '\r') {
                                bos.write(EOL);
                            } else {
                                // not a line ending, just output
                                bos.write(b);
                            }
                        }
                        // store this byte so that we can compare it for line endings
                        lastByte = b;
                    }
                } else {
                    bos.write(buff, 0, count);
                }

                transferredSize += count;

                notifyObserver();
            }
        } catch(IOException e) {
            LOG.warn("Exception during data transfer, closing data connection socket", e);
            factory.closeDataConnection();
            throw e;
        } catch(RuntimeException e) {
            LOG.warn("Exception during data transfer, closing data connection socket", e);
            factory.closeDataConnection();
            throw e;
        } finally {
            if (bos != null) {
                bos.flush();
            }
        }

        return transferredSize;
    }