/*
 *
 * Copyright (c) 1998 Scott Oaks. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and
 * without fee is hereby granted.
 *
 * This sample source code is provided for example only,
 * on an unsupported, as-is basis. 
 *
 * AUTHOR MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE, OR NON-INFRINGEMENT. AUTHOR SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 *
 * THIS SOFTWARE IS NOT DESIGNED OR INTENDED FOR USE OR RESALE AS ON-LINE
 * CONTROL EQUIPMENT IN HAZARDOUS ENVIRONMENTS REQUIRING FAIL-SAFE
 * PERFORMANCE, SUCH AS IN THE OPERATION OF NUCLEAR FACILITIES, AIRCRAFT
 * NAVIGATION OR COMMUNICATION SYSTEMS, AIR TRAFFIC CONTROL, DIRECT LIFE
 * SUPPORT MACHINES, OR WEAPONS SYSTEMS, IN WHICH THE FAILURE OF THE
 * SOFTWARE COULD LEAD DIRECTLY TO DEATH, PERSONAL INJURY, OR SEVERE
 * PHYSICAL OR ENVIRONMENTAL DAMAGE ("HIGH RISK ACTIVITIES").  AUTHOR
 * SPECIFICALLY DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR
 * HIGH RISK ACTIVITIES.
 */


import java.net.*;
import java.io.*;
import java.security.*;

public class JavaRunnerLoader extends SecureClassLoader {
	protected URL urlBase;	
	public boolean printLoadMessages = true;

	public JavaRunnerLoader(String base, ClassLoader parent) {
		super(parent);
		try {
			if (!(base.endsWith("/")))
				base = base + "/";
			urlBase = new URL(base);
		} catch (Exception e) {
			throw new IllegalArgumentException(base);
		}
	}

	byte[] getClassBytes(InputStream is) {
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		BufferedInputStream bis = new BufferedInputStream(is);
		boolean eof = false;
		while (!eof) {
			try {
				int i = bis.read();
				if (i == -1)
					eof = true;
				else baos.write(i);
			} catch (IOException e) {
				return null;
			}
		}
		return baos.toByteArray();
	}

	// Starting in 1.2 beta 4, the name of this method has changed from
	// findLocalClass to findClass
	protected Class findClass(String name) {
		String urlName = name.replace('.', '/');
		byte buf[];
		Class cl;

		SecurityManager sm = System.getSecurityManager();
		if (sm != null) {
			int i = name.lastIndexOf('.');
			if (i >= 0)
				sm.checkPackageDefinition(name.substring(0, i));
		}
		try {
			URL url = new URL(urlBase, urlName + ".class");
			if (printLoadMessages)
				System.out.println("Loading " + url);
			InputStream is = url.openConnection().getInputStream();
			buf = getClassBytes(is);
			// Starting in 1.2 beta 4, we no longer use a code source in
			// this example
			// CodeSource cs = getCodeSource(urlBase, null);
			// cl = defineClass(name, buf, 0, buf.length, cs, null);
			cl = defineClass(name, buf, 0, buf.length);
			return cl;
		} catch (Exception e) {
			System.out.println("Can't load " + name + ": " + e);
			return null;
		}
	}

	public void checkPackageAccess(String name) {
		SecurityManager sm = System.getSecurityManager();
		if (sm != null)
			sm.checkPackageAccess(name);
	}
}