EDIT

/*******************************************************************************

 * Copyright (c) 2005 IBM Corporation and others.

 * All rights reserved. This program and the accompanying materials

 * are made available under the terms of the Eclipse Public License v1.0

 * which accompanies this distribution, and is available at

 * http://www.eclipse.org/legal/epl-v10.html

 *

 * Contributors:

 *     IBM Corporation - initial API and implementation

 *******************************************************************************/

package org.eclipse.pde.internal.runtime.logview;

import java.io.File;

import java.io.IOException;

import java.io.InputStream;

import java.io.RandomAccessFile;

public class TailInputStream extends InputStream {

	private RandomAccessFile fRaf;

	private long fTail;

	public TailInputStream(File file, long maxLength) throws IOException {

		super();

		fTail = maxLength;

		fRaf = new RandomAccessFile(file, "r"); //$NON-NLS-1$

		skipHead(file);

	}

	private void skipHead(File file) throws IOException {

		if (file.length() > fTail) {

			fRaf.seek(file.length() - fTail);

			// skip bytes until a new line to be sure we start from a beginnng of valid UTF-8 character

			int c= read();

			while(c!='\n' && c!='r' && c!=-1){

				c=read();

			}

		}

	}

	public int read() throws IOException {

		byte[] b = new byte[1];

		int len = fRaf.read(b, 0, 1);

		if (len < 0) {

			return len;

		}

		return b[0];

	}

	public int read(byte[] b) throws IOException {

		return fRaf.read(b, 0, b.length);

	}

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

		return fRaf.read(b, off, len);

	}

	public void close() throws IOException {

		fRaf.close();

	}

}