Rename project to sshlib

1 files changed, 229 insertions, 0 deletions

diff --git a/sshlib/src/main/java/com/trilead/ssh2/StreamGobbler.java b/sshlib/src/main/java/com/trilead/ssh2/StreamGobbler.java
new file mode 100644
index 0000000..e93c388
--- /dev/null
+++ b/sshlib/src/main/java/com/trilead/ssh2/StreamGobbler.java
@@ -0,0 +1,229 @@
+
+package com.trilead.ssh2;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * A <code>StreamGobbler</code> is an InputStream that uses an internal worker
+ * thread to constantly consume input from another InputStream. It uses a buffer
+ * to store the consumed data. The buffer size is automatically adjusted, if needed.
+ * <p>
+ * This class is sometimes very convenient - if you wrap a session's STDOUT and STDERR
+ * InputStreams with instances of this class, then you don't have to bother about
+ * the shared window of STDOUT and STDERR in the low level SSH-2 protocol,
+ * since all arriving data will be immediatelly consumed by the worker threads.
+ * Also, as a side effect, the streams will be buffered (e.g., single byte
+ * read() operations are faster).
+ * <p>
+ * Other SSH for Java libraries include this functionality by default in
+ * their STDOUT and STDERR InputStream implementations, however, please be aware
+ * that this approach has also a downside:
+ * <p>
+ * If you do not call the StreamGobbler's <code>read()</code> method often enough
+ * and the peer is constantly sending huge amounts of data, then you will sooner or later
+ * encounter a low memory situation due to the aggregated data (well, it also depends on the Java heap size).
+ * Joe Average will like this class anyway - a paranoid programmer would never use such an approach.
+ * <p>
+ * The term "StreamGobbler" was taken from an article called "When Runtime.exec() won't",
+ * see http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html.
+ * 
+ * @author Christian Plattner, plattner@trilead.com
+ * @version $Id: StreamGobbler.java,v 1.1 2007/10/15 12:49:56 cplattne Exp $
+ */
+
+public class StreamGobbler extends InputStream
+{
+	class GobblerThread extends Thread
+	{
+		public void run()
+		{
+			byte[] buff = new byte[8192];
+
+			while (true)
+			{
+				try
+				{
+					int avail = is.read(buff);
+
+					synchronized (synchronizer)
+					{
+						if (avail <= 0)
+						{
+							isEOF = true;
+							synchronizer.notifyAll();
+							break;
+						}
+						
+						int space_available = buffer.length - write_pos;
+						
+						if (space_available < avail)
+						{
+							/* compact/resize buffer */
+
+							int unread_size = write_pos - read_pos;
+							int need_space = unread_size + avail;
+
+							byte[] new_buffer = buffer;
+
+							if (need_space > buffer.length)
+							{
+								int inc = need_space / 3;
+								inc = (inc < 256) ? 256 : inc;
+								inc = (inc > 8192) ? 8192 : inc;
+								new_buffer = new byte[need_space + inc];
+							}
+							
+							if (unread_size > 0)
+								System.arraycopy(buffer, read_pos, new_buffer, 0, unread_size);
+
+							buffer = new_buffer;
+							
+							read_pos = 0;
+							write_pos = unread_size;
+						}
+						
+						System.arraycopy(buff, 0, buffer, write_pos, avail);
+						write_pos += avail;
+
+						synchronizer.notifyAll();
+					}	
+				}
+				catch (IOException e)
+				{
+					synchronized (synchronizer)
+					{
+						exception = e;
+						synchronizer.notifyAll();
+						break;
+					}
+				}
+			}
+		}
+	}
+
+	private InputStream is;
+	private GobblerThread t;
+
+	private Object synchronizer = new Object();
+
+	private boolean isEOF = false;
+	private boolean isClosed = false;
+	private IOException exception = null;
+
+	private byte[] buffer = new byte[2048];
+	private int read_pos = 0;
+	private int write_pos = 0;
+
+	public StreamGobbler(InputStream is)
+	{
+		this.is = is;
+		t = new GobblerThread();
+		t.setDaemon(true);
+		t.start();
+	}
+
+	public int read() throws IOException
+	{
+		synchronized (synchronizer)
+		{
+			if (isClosed)
+				throw new IOException("This StreamGobbler is closed.");
+
+			while (read_pos == write_pos)
+			{
+				if (exception != null)
+					throw exception;
+
+				if (isEOF)
+					return -1;
+
+				try
+				{
+					synchronizer.wait();
+				}
+				catch (InterruptedException e)
+				{
+				}
+			}
+
+			int b = buffer[read_pos++] & 0xff;
+
+			return b;
+		}
+	}
+
+	public int available() throws IOException
+	{
+		synchronized (synchronizer)
+		{
+			if (isClosed)
+				throw new IOException("This StreamGobbler is closed.");
+
+			return write_pos - read_pos;
+		}
+	}
+
+	public int read(byte[] b) throws IOException
+	{
+		return read(b, 0, b.length);
+	}
+
+	public void close() throws IOException
+	{
+		synchronized (synchronizer)
+		{
+			if (isClosed)
+				return;
+			isClosed = true;
+			isEOF = true;
+			synchronizer.notifyAll();
+			is.close();
+		}
+	}
+
+	public int read(byte[] b, int off, int len) throws IOException
+	{
+		if (b == null)
+			throw new NullPointerException();
+
+		if ((off < 0) || (len < 0) || ((off + len) > b.length) || ((off + len) < 0) || (off > b.length))
+			throw new IndexOutOfBoundsException();
+
+		if (len == 0)
+			return 0;
+
+		synchronized (synchronizer)
+		{
+			if (isClosed)
+				throw new IOException("This StreamGobbler is closed.");
+
+			while (read_pos == write_pos)
+			{
+				if (exception != null)
+					throw exception;
+
+				if (isEOF)
+					return -1;
+
+				try
+				{
+					synchronizer.wait();
+				}
+				catch (InterruptedException e)
+				{
+				}
+			}
+
+			int avail = write_pos - read_pos;
+
+			avail = (avail > len) ? len : avail;
+
+			System.arraycopy(buffer, read_pos, b, off, avail);
+
+			read_pos += avail;
+
+			return avail;
+		}
+	}
+}