/src/main/java/com/alvermont/terraj/fracplanet/io/JarLibraryLoader.java

/*

 * Java Terrain and Stellar System Ports

 *

 * Copyright (C) 2006 Martin H. Smith based on work by original

 * authors.

 *

 * Released under the terms of the GNU General Public License

 *

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

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 *

 * This program 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 for more details.

 *

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

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,

 * MA  02110-1301, USA.

 *

 * Linking TerraJ statically or dynamically with other modules is making a

 * combined work based on TerraJ. Thus, the terms and conditions of the

 * GNU General Public License cover the whole combination.

 *

 * In addition, as a special exception, the copyright holders of TerraJ

 * give you permission to combine this program with free software programs

 * or libraries that are released under the GNU LGPL and with code included

 * in the standard release of JOGL, Java Getopt and FreeMarker under the BSD

 * license (or modified versions of such code, with unchanged license) and with

 * Apache Commons and Log4J libraries under the Apache license (or modified versions

 * of such code. You may copy and distribute such a system following the terms

 * of the GNU GPL for TerraJ and the licenses of the other code concerned,

 * provided that you include the source code of that other code when and as the

 * GNU GPL requires distribution of source code.

 *

 * Note that people who make modified versions of TerraJ are not obligated to grant

 * this special exception for their modified versions; it is their choice whether

 * to do so. The GNU General Public License gives permission to release a modified

 * version without this exception; this exception also makes it possible to release

 * a modified version which carries forward this exception.

 */



/*

 * JarLibraryLoader.java

 *

 * Created on 26 April 2006, 09:05

 */



package com.alvermont.terraj.fracplanet.io;



import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.lang.reflect.Field;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;



/**

 * Attempt to load native libraries from Jar files. Some of the code for this

 * came from:

 *

 * http://forum.java.sun.com/thread.jspa?forumID=406&messageID=2102477&threadID=439060

 *

 * I've modified it not to be specific to Windows. It's not a brilliant solution

 * but there seems to be little better that can be done given the difficulty

 * of platform independent native library loading.

 *

 * @author  martin

 * @version $Id: JarLibraryLoader.java,v 1.9 2006/07/06 07:46:59 martin Exp $

 */

public class JarLibraryLoader

{

    /** Our logger object */

    private static Log log = LogFactory.getLog(JarLibraryLoader.class);

    

    /** Creates a new instance of JarLibraryLoader */

    public JarLibraryLoader()

    {

    }

    

    /**

     * Get the name of a library file on this system given a base name.

     * 

     * @param name The base name of the library eg jogl

     * @return The name of the corresponding library file eg. libjogl.so on 

     * Linux

     */



    private static String getLibraryName(String name)

    {

        String platform = System.getProperty("os.name");



        String libname = "";

        

        if (platform.startsWith("Windows"))

        {

            // no prefix

        }

        else if (platform.equalsIgnoreCase("Mac OS"))

        {

            libname = "lib";

        }

        else

        {

            libname = "lib";

        }        

        

        return libname + name + getLibraryNameSuffix();

    }

    

    /**

     * Return the suffix (extension) of a library file on this system

     *

     * @return The name of a library file on this system e.g ".so" on Unix or

     * ".dll" on Windows.

     */

    

    private static String getLibraryNameSuffix()

    {

        String platform = System.getProperty("os.name");



        String suffix = "";

        

        if (platform.startsWith("Windows"))

        {

            suffix = ".dll";

        }

        else if (platform.equalsIgnoreCase("Mac OS"))

        {

            suffix = ".jnlib";

        }

        else

        {

            suffix = ".so";

        }        

        

        return suffix;

    }

    

    /**

     * Adds our extraction path to the system library path.

     *

     * @throws NoSuchFieldException if there is a reflection error

     * @throws IllegalAccessException if there is an access error during reflection

     */    

    public static void setupPath() throws NoSuchFieldException, IllegalAccessException

    {

        String dir = System.getProperty("user.home");



        dir = new File(dir).getPath();



        String newLibPath = dir + File.pathSeparator +

        System.getProperty("java.library.path");

        System.setProperty("java.library.path", newLibPath);



        Field fieldSysPath = ClassLoader.class.getDeclaredField("sys_paths");

        fieldSysPath.setAccessible(true);

        if (fieldSysPath != null) 

        {

            fieldSysPath.set(System.class.getClassLoader(), null);

        }



        log.debug("Lib path: " + newLibPath);

    }

    

    /**

     * Get the name of a library resource for this platform

     * 

     * @param name The name of the library

     * @return The resource name to use to look up the library

     */

    private static String getLibraryResourceName(String name)

    {

        String platform = System.getProperty("os.name");

        

        log.debug("Platform is: " + platform);

        

        String path = "/lib/natives_";

        

        if (platform.startsWith("Windows"))

        {

            path += "win32/" + name + ".dll";

        }

        else if (platform.equalsIgnoreCase("Mac OS"))

        {

            path += "macos/lib" + name + ".jnlib";

        }

        else

        {

            path += platform.toLowerCase() + "/lib" + name + ".so";

        }

        

        log.debug("Path is: " + path);



        return path;

    }

    

    /**

     * Extracts a file from the jar so it can be found as a library. There

     * is no way to load a library directly from the jar file. Uses the 

     * users current directory to write the jar file, which might not work,

     * should probably fall back to the home dir. We can't use createTempFile

     * for this as we have to preserve the library filename so that dependencies

     * can be correctly resolved. The extracted file is marked for deletion on

     * exit.

     *

     * @param name The name of the file to be extracted

     * @throws IOException if there is an error extracting the library.

     */    

    public static File extractLibrary(String name) throws IOException

    {

        try

        {

            // Gets a stream to the library file



            File temporaryDll = null;

            

            InputStream inputStream = JarLibraryLoader.class.

                    getResourceAsStream(getLibraryResourceName(name));



            if (inputStream != null)

            {

                temporaryDll = new File(System.getProperty("user.home") + 

                        File.separator + name + getLibraryNameSuffix());



                String dir = System.getProperty("user.home");



                temporaryDll = new File(dir, getLibraryName(name));

                temporaryDll.deleteOnExit();



                FileOutputStream outputStream = new FileOutputStream(temporaryDll);



                byte[] array = new byte[8192];



                for (int i = inputStream.read(array); i != -1; i = inputStream.read(array))

                {

                    outputStream.write(array, 0, i);

                }



                outputStream.close();

            }



            return temporaryDll;

        }

        catch (IOException ioe)

        {

            log.error("IOException loading library", ioe);

            

            throw ioe;

        }        

    }

    

    /**

     * Loads a native library. The native library is assumed

     * to be in a platform specific subdirectory of the lib directory in the jar. 

     * The library is writen to a local temporary directory and (hopefully) 

     * deleted at JVM exit.

     *

     * Dll extraction code taken from Gabriele Piero Nizzoli

     * http://www.nizzoli.net/index.php?itemid=15

     *

     * @param name The base name of the library to be loaded

     * @throws IOException if there is a problem loading the library

     */

    public static void loadLibrary(String name) throws IOException

    {

        try

        {

            File libFile = extractLibrary(name);

            

            if (libFile != null)

            {

                log.debug("Calling System.load on: " + libFile.getPath());



                System.load(libFile.getPath());

            }

        }

        catch (IOException ioe)

        {

            log.error("IOException loading library", ioe);

            

            throw ioe;

        }        

    }

}