com.dalsemi.shell.server
Class SystemInputStream

java.lang.Object
  |
  +--java.io.InputStream
        |
        +--com.dalsemi.shell.server.SystemInputStream

Direct Known Subclasses:

SerialInputStream, TelnetInputStream

public class SystemInputStream

extends InputStream

This is an implementation of an InputStream for use as System.in. Since the underlying root InputStream for a TINI program can come from a serial port, a socket, or any other kind of input, the differing behaviors of these input devices must be reconciled by this class. This class must ensure that input becomes available only after an end of line sequence is received, and that the amount available does not represent any 'inaccessible' data (if the data has not been followed by an end of line character). It must also handle '\r', '\n', and '\r\n' as end of line sequences.

See Also:

SystemPrintStream, Session

Field Summary

protected byte[]	buffer The internal buffer that holds all the data that has been received and not yet read by an application.
protected boolean	ECHO Indicates whether or not to echo the character just read.
protected int	endPos The ending position in the internal buffer where valid data ends.
protected static byte[]	ERASE Byte sequence for a backspace.
String	fileInName If this SystemInputStream reads from a file, this represents the name of the file.
protected PrintStream	out The 'echo' stream.
protected boolean	rawMode Indicates that the SystemInputStream should return data as soon as it is available, and not wait until an end of line sequence is received.
protected InputStream	root The underlying InputStream that this reads from.
protected Session	session The user session that owns this SystemInputStream.
protected int	startPos The starting position in the internal buffer where valid data is located.

Constructor Summary

SystemInputStream(InputStream in, PrintStream out)
Creates a new SystemPrintStream with the specified underlying root stream and echo stream.

SystemInputStream(InputStream in, PrintStream out, String fileInName)
Creates a new SystemInputStream with the specified underlying root stream and echo stream.

Method Summary

int	available() Returns the number of bytes that can be read from this input stream without blocking.
boolean	errorOccurred()
InputStream	getRootStream() Returns the underlying root InputStream of this stream.
protected void	increaseBuffer(int newDataSize) Ensures the internal buffer is large enough for more data.
protected int	rawAvailable() This method should be overridden by subclassing InputStreams.
protected int	rawRead() This method should be overridden by subclassing InputStreams.
protected int	rawRead(byte[] buff, int off, int len) Reads from the underlying stream and returns data even if an end of line sequence is not received.
int	read() Reads the next character from the stream.
int	read(byte[] buff, int off, int len) Tries to read len bytes from the stream.
String	readLine() Reads a line of text up to but not including the end of line sequence.
void	setEcho(boolean echo) Turns on and off echoing back characters read by this stream.
void	setEchoStream(PrintStream echo) Sets the PrintStream to echo back characters read by this stream.
void	setRawMode(boolean rawMode) Sets the mode for reading data from the underlying stream.
void	setRootStream(InputStream newIn) Sets the underlying InputStream to use.
void	setSession(Session session) Informs this stream of its owning session.

Methods inherited from class java.io.InputStream

close, mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

session

protected Session session

The user session that owns this SystemInputStream.

root

protected InputStream root

The underlying InputStream that this reads from.

out

protected PrintStream out

The 'echo' stream. If ECHO is true, this PrintStream will write everything it reads. This is useful in a telnet session, for instance, when a user types something and it needs to be echoed back to the telnet client.

See Also:

ECHO

rawMode

protected boolean rawMode

Indicates that the SystemInputStream should return data as soon as it is available, and not wait until an end of line sequence is received.

See Also:

rawRead(), rawRead(byte[],int,int)

buffer

protected byte[] buffer

The internal buffer that holds all the data that has been received and not yet read by an application.

startPos

protected int startPos

The starting position in the internal buffer where valid data is located.

endPos

protected int endPos

The ending position in the internal buffer where valid data ends. This is the next available offset for new data into the internal buffer.

fileInName

public String fileInName

If this SystemInputStream reads from a file, this represents the name of the file.

ECHO

protected boolean ECHO

Indicates whether or not to echo the character just read.

See Also:

out

ERASE

protected static final byte[] ERASE

Byte sequence for a backspace. (Arrow back, overwrite next character, then arrow back again.)

Constructor Detail

SystemInputStream

public SystemInputStream(InputStream in,
                         PrintStream out)

Creates a new SystemPrintStream with the specified underlying root stream and echo stream.

Parameters:

in - underlying InputStream to use

out - stream for echo characters

SystemInputStream

public SystemInputStream(InputStream in,
                         PrintStream out,
                         String fileInName)

Creates a new SystemInputStream with the specified underlying root stream and echo stream. Calling this constructor signifies that the underlying InputStream is reading from a file.

Parameters:

in - underlying InputStream to use

out - stream for echo characters

fileInName - name of the file this stream is reading from

Method Detail

setEcho

public void setEcho(boolean echo)

Turns on and off echoing back characters read by this stream. This is useful if a session is reading a password, it will not be echoed back to the session.

Parameters:

echo - true to enable echoing, false to disable it

See Also:

setEchoStream(java.io.PrintStream)

setEchoStream

public void setEchoStream(PrintStream echo)

Sets the PrintStream to echo back characters read by this stream. Note: you must call setEcho(true) to enable echoing.

Parameters:

echo - stream to echo back characters read

See Also:

setEcho(boolean)

setSession

public void setSession(Session session)

Informs this stream of its owning session. This allows this stream to call into the session when needed.

Parameters:

session - the owning session

rawRead

protected int rawRead()
               throws IOException

This method should be overridden by subclassing InputStreams. It should only be called from within a synchronized block. It blocks until data is available and returns the first value it reads. It does not wait for an end of line sequence.

Returns:

the value read from the underlying stream

Throws:

IOException - if an error occurs reading from the underlying stream.

See Also:

rawRead(byte[],int,int), rawAvailable(), setRawMode(boolean)

rawRead

protected int rawRead(byte[] buff,
                      int off,
                      int len)
               throws IOException

Reads from the underlying stream and returns data even if an end of line sequence is not received. If not operating in raw reading mode, it also checks and handles backspace events. Stops if it finds an end of stream.

This method should only be called from within a synchronized block.

Returns:

number of bytes read

Throws:

IOException - if an error occurs reading from the underlying stream

See Also:

rawRead(), setRawMode(boolean), rawAvailable()

rawAvailable

protected int rawAvailable()
                    throws IOException

This method should be overridden by subclassing InputStreams. It returns the amount available from the underlying root stream. This is not the amount available if the SystemInputStream is not in raw mode.

Returns:

amount of data available directly from the underlying stream

Throws:

IOException - if an error occurs in the underlying stream.

See Also:

setRawMode(boolean), rawRead(), rawRead(byte[],int,int)

readLine

public String readLine()

Reads a line of text up to but not including the end of line sequence. This method will wait for more input if an end of line sequence or the end of the stream cannot be found. This method recognizes '\r', '\n', and '\r\n' and end of line sequences. If the end of the stream is reached, null is returned. Blank lines are returned as empty strings (a String of length 0).

Returns:

next line of text available from the underlying InputStream, or null if no more input will be available due to the end of the stream

See Also:

read(), read(byte[],int,int)

read

public final int read()
               throws IOException

Reads the next character from the stream. If raw mode is not enabled, this method will only return data that has been followed by an end of line sequence.

Overrides:

read in class InputStream

Returns:

the next character from the stream, or -1 if the end of the stream has been reached

Throws:

IOException - if an error occurs in the underlying stream

See Also:

setRawMode(boolean), readLine(), read(byte[],int,int)

read

public int read(byte[] buff,
                int off,
                int len)
         throws IOException

Tries to read len bytes from the stream. If the end of stream is encountered, no more data will be read. If raw mode is not enabled, only data that has been followed by an end of line sequence or the end of the stream will be reported. This method will block until enough data is available to return or the end of the stream is reached.

Overrides:

read in class InputStream

Parameters:

buff - byte array to store the data read

off - offset to begin storing data in the array

len - amount of data requested

Returns:

the number of characters read, or -1 if the end of the stream has been reached

Throws:

IOException - if an error occurs in the underlying stream

See Also:

read(), readLine(), setRawMode(boolean)

increaseBuffer

protected void increaseBuffer(int newDataSize)

Ensures the internal buffer is large enough for more data. This method should only be called from within a synchronized block.

Parameters:

newDataSize - the amount of new data that is about to be copied into the buffer at location endPos

available

public final int available()
                    throws IOException

Returns the number of bytes that can be read from this input stream without blocking. This is equivalent to the number of bytes that have been followed by end of line sequences (or by the end of the stream), including the end of line sequences.

Overrides:

available in class InputStream

Returns:

the number of bytes that can be read from this input stream without blocking

Throws:

IOException - if an error occurs in the underlying stream

See Also:

setRawMode(boolean)

setRawMode

public void setRawMode(boolean rawMode)

Sets the mode for reading data from the underlying stream. If raw mode is set to true, any call to read data will return the next available data from the underlying stream. If raw mode is false, read calls only report data that has been followed by an end of line character, or the end of the stream, even if the read must block to do so.

Parameters:

rawMode - false to block for an end of line sequence, true to return any available data

See Also:

rawRead(), rawRead(byte[],int,int), rawAvailable(), read(), read(byte[],int,int), available()

setRootStream

public void setRootStream(InputStream newIn)

Sets the underlying InputStream to use.

Parameters:

newIn - new root InputStream to use

See Also:

getRootStream()

getRootStream

public InputStream getRootStream()

Returns the underlying root InputStream of this stream.

Returns:

the root stream

See Also:

setRootStream(java.io.InputStream)

errorOccurred

public boolean errorOccurred()