/*

 * Copyright (c) 2005, 2008, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

package sun.jvm.hotspot;

import java.io.*;

import java.net.*;

import java.util.*;

import java.security.*;

/**

 * SA uses native debugger back-end library - libsaproc.so on Unix platforms.

 * Starting from 5.0, in Solaris & Linux JDK "libsaproc.so" is shipped with JDK

 * and is kept jre/lib/cpu directory (where all other JDK platform libraries

 * are kept). This implies that always that jre copy of libsaproc.so will be

 * used and the copy of libsaproc.so built from SA sources here will not

 * be used at all. We can override libsaproc.so using this class loader

 * as System class loader using "java.system.class.loader" property. This

 * class loader loads classes paths specified paths using the System property

 * "java.class.path". Because, this class loader loads SA debugger classes

 * (among other classes), JVM calls findLibrary override here. In this

 * findLibrary, we first check the library in the directories specified through

 * "sa.library.path" System property. This way updated/latest SA native library

 * can be loaded instead of the one from JDK's jre/lib directory.

 */

public class SALauncherLoader extends URLClassLoader {

    /**

     * Checks native libraries under directories specified using

     * the System property "sa.library.path".

     */

    public String findLibrary(String name) {

        name = System.mapLibraryName(name);

        for (int i = 0; i < libpaths.length; i++) {

            File file = new File(new File(libpaths[i]), name);

            if (file.exists()) {

                return file.getAbsolutePath();

            }

        }

        return null;

    }

    public SALauncherLoader(ClassLoader parent) {

        super(getClassPath(), parent);

        String salibpath = System.getProperty("sa.library.path");

        if (salibpath != null) {

            libpaths = salibpath.split(File.pathSeparator);

        } else {

            libpaths = new String[0];

        }

    }

    /**

     * Override loadClass so we can checkPackageAccess.

     */

    public synchronized Class loadClass(String name, boolean resolve)

            throws ClassNotFoundException {

        int i = name.lastIndexOf('.');

        if (i != -1) {

            SecurityManager sm = System.getSecurityManager();

            if (sm != null) {

                sm.checkPackageAccess(name.substring(0, i));

            }

        }

        Class clazz = findLoadedClass(name);

        if (clazz != null) return clazz;

        /*

         * NOTE: Unlike 'usual' class loaders, we do *not* delegate to

         * the parent loader first. We attempt to load the class

         * ourselves first and use parent loader only if we can't load.

         * This is because the parent of this loader is 'default'

         * System loader that can 'see' all SA classes in classpath and

         * so will load those if delegated. And if parent loads SA classes,

         * then JVM won't call findNative override in this class.

         */

        try {

            return findClass(name);

        } catch (ClassNotFoundException cnfe) {

            return (super.loadClass(name, resolve));

        }

    }

    /**

     * allow any classes loaded from classpath to exit the VM.

     */

    protected PermissionCollection getPermissions(CodeSource codesource) {

        PermissionCollection perms = super.getPermissions(codesource);

        perms.add(new RuntimePermission("exitVM"));

        return perms;

    }

    //-- Internals only below this point

    private String[] libpaths;

    private static URL[] getClassPath() {

        final String s = System.getProperty("java.class.path");

        final File[] path = (s == null) ? new File[0] : getClassPath(s);

        return pathToURLs(path);

    }

    private static URL[] pathToURLs(File[] path) {

        URL[] urls = new URL[path.length];

        for (int i = 0; i < path.length; i++) {

            urls[i] = getFileURL(path[i]);

        }

        return urls;

    }

    private static File[] getClassPath(String cp) {

        String[] tmp = cp.split(File.pathSeparator);

        File[] paths = new File[tmp.length];

        for (int i = 0; i < paths.length; i++) {

            paths[i] = new File(tmp[i].equals("")? "." : tmp[i]);

        }

        return paths;

    }

    private static URL getFileURL(File file) {

        try {

            file = file.getCanonicalFile();

        } catch (IOException e) {

            e.printStackTrace();

        }

        try {

            return file.toURI().toURL();

        } catch (MalformedURLException mue) {

            throw new InternalError(mue.getMessage());

        }

    }

}