jdk/src/share/classes/sun/misc/ExtensionDependency.java - edge/openjdk - Git at Google

 /*
  * Copyright (c) 1999, 2013, 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.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * 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.misc;

 import java.io.File;
 import java.io.FilenameFilter;
 import java.io.IOException;
 import java.io.FileNotFoundException;
 import java.util.StringTokenizer;
 import java.util.Vector;
 import java.util.Enumeration;
 import java.util.jar.JarFile;
 import java.util.jar.Manifest;
 import java.util.jar.Attributes;
 import java.util.jar.Attributes.Name;
 import java.security.AccessController;
 import java.security.PrivilegedAction;
 import java.security.PrivilegedExceptionAction;
 import java.security.PrivilegedActionException;
 import java.net.URL;
 import java.net.MalformedURLException;
 import sun.net.www.ParseUtil;

 /**
  * <p>
  * This class checks dependent extensions a particular jar file may have
  * declared through its manifest attributes.
  * </p>
  * Jar file declared dependent extensions through the extension-list
  * attribute. The extension-list contains a list of keys used to
  * fetch the other attributes describing the required extension.
  * If key is the extension key declared in the extension-list
  * attribute, the following describing attribute can be found in
  * the manifest :
  * key-Extension-Name:  (Specification package name)
  * key-Specification-Version: (Specification-Version)
  * key-Implementation-Version: (Implementation-Version)
  * key-Implementation-Vendor-Id: (Imlementation-Vendor-Id)
  * key-Implementation-Version: (Implementation version)
  * key-Implementation-URL: (URL to download the requested extension)
  * <p>
  * This class also maintain versioning consistency of installed
  * extensions dependencies declared in jar file manifest.
  * </p>
  * @author  Jerome Dochez
  */
 public class ExtensionDependency {

     /* Callbak interfaces to delegate installation of missing extensions */
     private static Vector<ExtensionInstallationProvider> providers;

     /**
      * <p>
      * Register an ExtensionInstallationProvider. The provider is responsible
      * for handling the installation (upgrade) of any missing extensions.
      * </p>
      * @param eip ExtensionInstallationProvider implementation
      */
     public synchronized static void addExtensionInstallationProvider
         (ExtensionInstallationProvider eip)
     {
         if (providers == null) {
             providers = new Vector<>();
         }
         providers.add(eip);
     }

     /**
      * <p>
      * Unregister a previously installed installation provider
      * </p>
      */
     public synchronized static void removeExtensionInstallationProvider
         (ExtensionInstallationProvider eip)
     {
         providers.remove(eip);
     }

     /**
      * <p>
      * Checks the dependencies of the jar file on installed extension.
      * </p>
      * @param jarFile containing the attriutes declaring the dependencies
      */
     public static boolean checkExtensionsDependencies(JarFile jar)
     {
         if (providers == null) {
             // no need to bother, nobody is registered to install missing
             // extensions
             return true;
         }

         try {
             ExtensionDependency extDep = new ExtensionDependency();
             return extDep.checkExtensions(jar);
         } catch (ExtensionInstallationException e) {
             debug(e.getMessage());
         }
         return false;
     }

     /*
      * Check for all declared required extensions in the jar file
      * manifest.
      */
     protected boolean checkExtensions(JarFile jar)
         throws ExtensionInstallationException
     {
         Manifest man;
         try {
             man = jar.getManifest();
         } catch (IOException e) {
             return false;
         }

         if (man == null) {
             // The applet does not define a manifest file, so
             // we just assume all dependencies are satisfied.
             return true;
         }

         boolean result = true;
         Attributes attr = man.getMainAttributes();
         if (attr != null) {
             // Let's get the list of declared dependencies
             String value = attr.getValue(Name.EXTENSION_LIST);
             if (value != null) {
                 StringTokenizer st = new StringTokenizer(value);
                 // Iterate over all declared dependencies
                 while (st.hasMoreTokens()) {
                     String extensionName = st.nextToken();
                     debug("The file " + jar.getName() +
                           " appears to depend on " + extensionName);
                     // Sanity Check
                     String extName = extensionName + "-" +
                         Name.EXTENSION_NAME.toString();
                     if (attr.getValue(extName) == null) {
                         debug("The jar file " + jar.getName() +
                               " appers to depend on "
                               + extensionName + " but does not define the " +
                               extName + " attribute in its manifest ");

                     } else {
                         if (!checkExtension(extensionName, attr)) {
                             debug("Failed installing " + extensionName);
                             result = false;
                         }
                     }
                 }
             } else {
                 debug("No dependencies for " + jar.getName());
             }
         }
         return result;
     }


     /*
      * <p>
      * Check that a particular dependency on an extension is satisfied.
      * </p>
      * @param extensionName is the key used for the attributes in the manifest
      * @param attr is the attributes of the manifest file
      *
      * @return true if the dependency is satisfied by the installed extensions
      */
     protected synchronized boolean checkExtension(final String extensionName,
                                      final Attributes attr)
         throws ExtensionInstallationException
     {
         debug("Checking extension " + extensionName);
         if (checkExtensionAgainstInstalled(extensionName, attr))
             return true;

         debug("Extension not currently installed ");
         ExtensionInfo reqInfo = new ExtensionInfo(extensionName, attr);
         return installExtension(reqInfo, null);
     }

     /*
      * <p>
      * Check if a particular extension is part of the currently installed
      * extensions.
      * </p>
      * @param extensionName is the key for the attributes in the manifest
      * @param attr is the attributes of the manifest
      *
      * @return true if the requested extension is already installed
      */
     boolean checkExtensionAgainstInstalled(String extensionName,
                                            Attributes attr)
         throws ExtensionInstallationException
     {
         File fExtension = checkExtensionExists(extensionName);

         if (fExtension != null) {
         // Extension already installed, just check against this one
             try {
                 if (checkExtensionAgainst(extensionName, attr, fExtension))
                     return true;
             } catch (FileNotFoundException e) {
                 debugException(e);
             } catch (IOException e) {
                 debugException(e);
             }
             return false;

         } else {
         // Not sure if extension is already installed, so check all the
         // installed extension jar files to see if we get a match

             File[] installedExts;

             try {
             // Get the list of installed extension jar files so we can
             // compare the installed versus the requested extension
                 installedExts = getInstalledExtensions();
             } catch(IOException e) {
                 debugException(e);
                 return false;
             }

             for (int i=0;i<installedExts.length;i++) {
                 try {
                     if (checkExtensionAgainst(extensionName, attr, installedExts[i]))
                         return true;
                 } catch (FileNotFoundException e) {
                     debugException(e);
                 } catch (IOException e) {
                     debugException(e);
                     // let's continue with the next installed extension
                 }
             }
         }
         return false;
     }

     /*
      * <p>
      * Check if the requested extension described by the attributes
      * in the manifest under the key extensionName is compatible with
      * the jar file.
      * </p>
      *
      * @param extensionName key in the attribute list
      * @param attr manifest file attributes
      * @param file installed extension jar file to compare the requested
      * extension against.
      */
     protected boolean checkExtensionAgainst(String extensionName,
                                             Attributes attr,
                                             final File file)
         throws IOException,
                FileNotFoundException,
                ExtensionInstallationException
     {

         debug("Checking extension " + extensionName +
               " against " + file.getName());

         // Load the jar file ...
         Manifest man;
         try {
             man = AccessController.doPrivileged(
                 new PrivilegedExceptionAction<Manifest>() {
                     public Manifest run()
                             throws IOException, FileNotFoundException {
                          if (!file.exists())
                              throw new FileNotFoundException(file.getName());
                          JarFile jarFile =  new JarFile(file);
                          return jarFile.getManifest();
                      }
                  });
         } catch(PrivilegedActionException e) {
             if (e.getException() instanceof FileNotFoundException)
                 throw (FileNotFoundException) e.getException();
             throw (IOException) e.getException();
         }

         // Construct the extension information object
         ExtensionInfo reqInfo = new ExtensionInfo(extensionName, attr);
         debug("Requested Extension : " + reqInfo);

         int isCompatible = ExtensionInfo.INCOMPATIBLE;
         ExtensionInfo instInfo = null;

         if (man != null) {
             Attributes instAttr = man.getMainAttributes();
             if (instAttr != null) {
                 instInfo = new ExtensionInfo(null, instAttr);
                 debug("Extension Installed " + instInfo);
                 isCompatible = instInfo.isCompatibleWith(reqInfo);
                 switch(isCompatible) {
                 case ExtensionInfo.COMPATIBLE:
                     debug("Extensions are compatible");
                     return true;

                 case ExtensionInfo.INCOMPATIBLE:
                     debug("Extensions are incompatible");
                     return false;

                 default:
                     // everything else
                     debug("Extensions require an upgrade or vendor switch");
                     return installExtension(reqInfo, instInfo);

                 }
             }
         }
         return false;
     }

     /*
      * <p>
      * An required extension is missing, if an ExtensionInstallationProvider is
      * registered, delegate the installation of that particular extension to it.
      * </p>
      *
      * @param reqInfo Missing extension information
      * @param instInfo Older installed version information
      *
      * @return true if the installation is successful
      */
     protected boolean installExtension(ExtensionInfo reqInfo,
                                        ExtensionInfo instInfo)
         throws ExtensionInstallationException
     {
         Vector<ExtensionInstallationProvider> currentProviders;
         synchronized(providers) {
             @SuppressWarnings("unchecked")
             Vector<ExtensionInstallationProvider> tmp =
                 (Vector<ExtensionInstallationProvider>) providers.clone();
             currentProviders = tmp;
         }
         for (Enumeration<ExtensionInstallationProvider> e = currentProviders.elements();
                 e.hasMoreElements();) {
             ExtensionInstallationProvider eip = e.nextElement();

             if (eip!=null) {
                 // delegate the installation to the provider
                 if (eip.installExtension(reqInfo, instInfo)) {
                     debug(reqInfo.name + " installation successful");
                     Launcher.ExtClassLoader cl = (Launcher.ExtClassLoader)
                         Launcher.getLauncher().getClassLoader().getParent();
                     addNewExtensionsToClassLoader(cl);
                     return true;
                 }
             }
         }
         // We have tried all of our providers, noone could install this
         // extension, we just return failure at this point
         debug(reqInfo.name + " installation failed");
         return false;
     }

     /**
      * <p>
      * Checks if the extension, that is specified in the extension-list in
      * the applet jar manifest, is already installed (i.e. exists in the
      * extension directory).
      * </p>
      *
      * @param extensionName extension name in the extension-list
      *
      * @return the extension if it exists in the extension directory
      */
     private File checkExtensionExists(String extensionName) {
         // Function added to fix bug 4504166
         final String extName = extensionName;
         final String[] fileExt = {".jar", ".zip"};

         return AccessController.doPrivileged(
             new PrivilegedAction<File>() {
                 public File run() {
                     try {
                         File fExtension;
                         File[] dirs = getExtDirs();

                         // Search the extension directories for the extension that is specified
                         // in the attribute extension-list in the applet jar manifest
                         for (int i=0;i<dirs.length;i++) {
                             for (int j=0;j<fileExt.length;j++) {
                                 if (extName.toLowerCase().endsWith(fileExt[j])) {
                                     fExtension = new File(dirs[i], extName);
                                 } else {
                                     fExtension = new File(dirs[i], extName+fileExt[j]);
                                 }
                                 debug("checkExtensionExists:fileName " + fExtension.getName());
                                 if (fExtension.exists()) {
                                     return fExtension;
                                 }
                             }
                         }
                         return null;

                     } catch(Exception e) {
                          debugException(e);
                          return null;
                     }
                 }
             });
     }

     /**
      * <p>
      * @return the java.ext.dirs property as a list of directory
      * </p>
      */
     private static File[] getExtDirs() {
         String s = java.security.AccessController.doPrivileged(
                 new sun.security.action.GetPropertyAction("java.ext.dirs"));

         File[] dirs;
         if (s != null) {
             StringTokenizer st =
                 new StringTokenizer(s, File.pathSeparator);
             int count = st.countTokens();
             debug("getExtDirs count " + count);
             dirs = new File[count];
             for (int i = 0; i < count; i++) {
                 dirs[i] = new File(st.nextToken());
                 debug("getExtDirs dirs["+i+"] "+ dirs[i]);
             }
         } else {
             dirs = new File[0];
             debug("getExtDirs dirs " + dirs);
         }
         debug("getExtDirs dirs.length " + dirs.length);
         return dirs;
     }

     /*
      * <p>
      * Scan the directories and return all files installed in those
      * </p>
      * @param dirs list of directories to scan
      *
      * @return the list of files installed in all the directories
      */
     private static File[] getExtFiles(File[] dirs) throws IOException {
         Vector<File> urls = new Vector<File>();
         for (int i = 0; i < dirs.length; i++) {
             String[] files = dirs[i].list(new JarFilter());
             if (files != null) {
                 debug("getExtFiles files.length " + files.length);
                 for (int j = 0; j < files.length; j++) {
                     File f = new File(dirs[i], files[j]);
                     urls.add(f);
                     debug("getExtFiles f["+j+"] "+ f);
                 }
             }
         }
         File[] ua = new File[urls.size()];
         urls.copyInto(ua);
         debug("getExtFiles ua.length " + ua.length);
         return ua;
     }

     /*
      * <p>
      * @return the list of installed extensions jar files
      * </p>
      */
     private File[] getInstalledExtensions() throws IOException {
         return AccessController.doPrivileged(
             new PrivilegedAction<File[]>() {
                 public File[] run() {
                      try {
                          return getExtFiles(getExtDirs());
                      } catch(IOException e) {
                          debug("Cannot get list of installed extensions");
                          debugException(e);
                         return new File[0];
                      }
                  }
             });
     }

     /*
      * <p>
      * Add the newly installed jar file to the extension class loader.
      * </p>
      *
      * @param cl the current installed extension class loader
      *
      * @return true if successful
      */
     private Boolean addNewExtensionsToClassLoader(Launcher.ExtClassLoader cl) {
         try {
             File[] installedExts = getInstalledExtensions();
             for (int i=0;i<installedExts.length;i++) {
                 final File instFile = installedExts[i];
                 URL instURL = AccessController.doPrivileged(
                     new PrivilegedAction<URL>() {
                         public URL run() {
                             try {
                                 return ParseUtil.fileToEncodedURL(instFile);
                             } catch (MalformedURLException e) {
                                 debugException(e);
                                 return null;
                             }
                         }
                     });
                 if (instURL != null) {
                     URL[] urls = cl.getURLs();
                     boolean found=false;
                     for (int j = 0; j<urls.length; j++) {
                         debug("URL["+j+"] is " + urls[j] + " looking for "+
                                            instURL);
                         if (urls[j].toString().compareToIgnoreCase(
                                     instURL.toString())==0) {
                             found=true;
                             debug("Found !");
                         }
                     }
                     if (!found) {
                         debug("Not Found ! adding to the classloader " +
                               instURL);
                         cl.addExtURL(instURL);
                     }
                 }
             }
         } catch (MalformedURLException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
             // let's continue with the next installed extension
         }
         return Boolean.TRUE;
     }

     // True to display all debug and trace messages
     static final boolean DEBUG = false;

     private static void debug(String s) {
         if (DEBUG) {
             System.err.println(s);
         }
     }

     private void debugException(Throwable e) {
         if (DEBUG) {
             e.printStackTrace();
         }
     }

 }
	/*
	* Copyright (c) 1999, 2013, 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. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* 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.misc;

	import java.io.File;
	import java.io.FilenameFilter;
	import java.io.IOException;
	import java.io.FileNotFoundException;
	import java.util.StringTokenizer;
	import java.util.Vector;
	import java.util.Enumeration;
	import java.util.jar.JarFile;
	import java.util.jar.Manifest;
	import java.util.jar.Attributes;
	import java.util.jar.Attributes.Name;
	import java.security.AccessController;
	import java.security.PrivilegedAction;
	import java.security.PrivilegedExceptionAction;
	import java.security.PrivilegedActionException;
	import java.net.URL;
	import java.net.MalformedURLException;
	import sun.net.www.ParseUtil;

	/**
	* <p>
	* This class checks dependent extensions a particular jar file may have
	* declared through its manifest attributes.
	* </p>
	* Jar file declared dependent extensions through the extension-list
	* attribute. The extension-list contains a list of keys used to
	* fetch the other attributes describing the required extension.
	* If key is the extension key declared in the extension-list
	* attribute, the following describing attribute can be found in
	* the manifest :
	* key-Extension-Name: (Specification package name)
	* key-Specification-Version: (Specification-Version)
	* key-Implementation-Version: (Implementation-Version)
	* key-Implementation-Vendor-Id: (Imlementation-Vendor-Id)
	* key-Implementation-Version: (Implementation version)
	* key-Implementation-URL: (URL to download the requested extension)
	* <p>
	* This class also maintain versioning consistency of installed
	* extensions dependencies declared in jar file manifest.
	* </p>
	* @author Jerome Dochez
	*/
	public class ExtensionDependency {

	/* Callbak interfaces to delegate installation of missing extensions */
	private static Vector<ExtensionInstallationProvider> providers;

	/**
	* <p>
	* Register an ExtensionInstallationProvider. The provider is responsible
	* for handling the installation (upgrade) of any missing extensions.
	* </p>
	* @param eip ExtensionInstallationProvider implementation
	*/
	public synchronized static void addExtensionInstallationProvider
	(ExtensionInstallationProvider eip)
	{
	if (providers == null) {
	providers = new Vector<>();
	}
	providers.add(eip);
	}

	/**
	* <p>
	* Unregister a previously installed installation provider
	* </p>
	*/
	public synchronized static void removeExtensionInstallationProvider
	(ExtensionInstallationProvider eip)
	{
	providers.remove(eip);
	}

	/**
	* <p>
	* Checks the dependencies of the jar file on installed extension.
	* </p>
	* @param jarFile containing the attriutes declaring the dependencies
	*/
	public static boolean checkExtensionsDependencies(JarFile jar)
	{
	if (providers == null) {
	// no need to bother, nobody is registered to install missing
	// extensions
	return true;
	}

	try {
	ExtensionDependency extDep = new ExtensionDependency();
	return extDep.checkExtensions(jar);
	} catch (ExtensionInstallationException e) {
	debug(e.getMessage());
	}
	return false;
	}

	/*
	* Check for all declared required extensions in the jar file
	* manifest.
	*/
	protected boolean checkExtensions(JarFile jar)
	throws ExtensionInstallationException
	{
	Manifest man;
	try {
	man = jar.getManifest();
	} catch (IOException e) {
	return false;
	}

	if (man == null) {
	// The applet does not define a manifest file, so
	// we just assume all dependencies are satisfied.
	return true;
	}

	boolean result = true;
	Attributes attr = man.getMainAttributes();
	if (attr != null) {
	// Let's get the list of declared dependencies
	String value = attr.getValue(Name.EXTENSION_LIST);
	if (value != null) {
	StringTokenizer st = new StringTokenizer(value);
	// Iterate over all declared dependencies
	while (st.hasMoreTokens()) {
	String extensionName = st.nextToken();
	debug("The file " + jar.getName() +
	" appears to depend on " + extensionName);
	// Sanity Check
	String extName = extensionName + "-" +
	Name.EXTENSION_NAME.toString();
	if (attr.getValue(extName) == null) {
	debug("The jar file " + jar.getName() +
	" appers to depend on "
	+ extensionName + " but does not define the " +
	extName + " attribute in its manifest ");

	} else {
	if (!checkExtension(extensionName, attr)) {
	debug("Failed installing " + extensionName);
	result = false;
	}
	}
	}
	} else {
	debug("No dependencies for " + jar.getName());
	}
	}
	return result;
	}


	/*
	* <p>
	* Check that a particular dependency on an extension is satisfied.
	* </p>
	* @param extensionName is the key used for the attributes in the manifest
	* @param attr is the attributes of the manifest file
	*
	* @return true if the dependency is satisfied by the installed extensions
	*/
	protected synchronized boolean checkExtension(final String extensionName,
	final Attributes attr)
	throws ExtensionInstallationException
	{
	debug("Checking extension " + extensionName);
	if (checkExtensionAgainstInstalled(extensionName, attr))
	return true;

	debug("Extension not currently installed ");
	ExtensionInfo reqInfo = new ExtensionInfo(extensionName, attr);
	return installExtension(reqInfo, null);
	}

	/*
	* <p>
	* Check if a particular extension is part of the currently installed
	* extensions.
	* </p>
	* @param extensionName is the key for the attributes in the manifest
	* @param attr is the attributes of the manifest
	*
	* @return true if the requested extension is already installed
	*/
	boolean checkExtensionAgainstInstalled(String extensionName,
	Attributes attr)
	throws ExtensionInstallationException
	{
	File fExtension = checkExtensionExists(extensionName);

	if (fExtension != null) {
	// Extension already installed, just check against this one
	try {
	if (checkExtensionAgainst(extensionName, attr, fExtension))
	return true;
	} catch (FileNotFoundException e) {
	debugException(e);
	} catch (IOException e) {
	debugException(e);
	}
	return false;

	} else {
	// Not sure if extension is already installed, so check all the
	// installed extension jar files to see if we get a match

	File[] installedExts;

	try {
	// Get the list of installed extension jar files so we can
	// compare the installed versus the requested extension
	installedExts = getInstalledExtensions();
	} catch(IOException e) {
	debugException(e);
	return false;
	}

	for (int i=0;i<installedExts.length;i++) {
	try {
	if (checkExtensionAgainst(extensionName, attr, installedExts[i]))
	return true;
	} catch (FileNotFoundException e) {
	debugException(e);
	} catch (IOException e) {
	debugException(e);
	// let's continue with the next installed extension
	}
	}
	}
	return false;
	}

	/*
	* <p>
	* Check if the requested extension described by the attributes
	* in the manifest under the key extensionName is compatible with
	* the jar file.
	* </p>
	*
	* @param extensionName key in the attribute list
	* @param attr manifest file attributes
	* @param file installed extension jar file to compare the requested
	* extension against.
	*/
	protected boolean checkExtensionAgainst(String extensionName,
	Attributes attr,
	final File file)
	throws IOException,
	FileNotFoundException,
	ExtensionInstallationException
	{

	debug("Checking extension " + extensionName +
	" against " + file.getName());

	// Load the jar file ...
	Manifest man;
	try {
	man = AccessController.doPrivileged(
	new PrivilegedExceptionAction<Manifest>() {
	public Manifest run()
	throws IOException, FileNotFoundException {
	if (!file.exists())
	throw new FileNotFoundException(file.getName());
	JarFile jarFile = new JarFile(file);
	return jarFile.getManifest();
	}
	});
	} catch(PrivilegedActionException e) {
	if (e.getException() instanceof FileNotFoundException)
	throw (FileNotFoundException) e.getException();
	throw (IOException) e.getException();
	}

	// Construct the extension information object
	ExtensionInfo reqInfo = new ExtensionInfo(extensionName, attr);
	debug("Requested Extension : " + reqInfo);

	int isCompatible = ExtensionInfo.INCOMPATIBLE;
	ExtensionInfo instInfo = null;

	if (man != null) {
	Attributes instAttr = man.getMainAttributes();
	if (instAttr != null) {
	instInfo = new ExtensionInfo(null, instAttr);
	debug("Extension Installed " + instInfo);
	isCompatible = instInfo.isCompatibleWith(reqInfo);
	switch(isCompatible) {
	case ExtensionInfo.COMPATIBLE:
	debug("Extensions are compatible");
	return true;

	case ExtensionInfo.INCOMPATIBLE:
	debug("Extensions are incompatible");
	return false;

	default:
	// everything else
	debug("Extensions require an upgrade or vendor switch");
	return installExtension(reqInfo, instInfo);

	}
	}
	}
	return false;
	}

	/*
	* <p>
	* An required extension is missing, if an ExtensionInstallationProvider is
	* registered, delegate the installation of that particular extension to it.
	* </p>
	*
	* @param reqInfo Missing extension information
	* @param instInfo Older installed version information
	*
	* @return true if the installation is successful
	*/
	protected boolean installExtension(ExtensionInfo reqInfo,
	ExtensionInfo instInfo)
	throws ExtensionInstallationException
	{
	Vector<ExtensionInstallationProvider> currentProviders;
	synchronized(providers) {
	@SuppressWarnings("unchecked")
	Vector<ExtensionInstallationProvider> tmp =
	(Vector<ExtensionInstallationProvider>) providers.clone();
	currentProviders = tmp;
	}
	for (Enumeration<ExtensionInstallationProvider> e = currentProviders.elements();
	e.hasMoreElements();) {
	ExtensionInstallationProvider eip = e.nextElement();

	if (eip!=null) {
	// delegate the installation to the provider
	if (eip.installExtension(reqInfo, instInfo)) {
	debug(reqInfo.name + " installation successful");
	Launcher.ExtClassLoader cl = (Launcher.ExtClassLoader)
	Launcher.getLauncher().getClassLoader().getParent();
	addNewExtensionsToClassLoader(cl);
	return true;
	}
	}
	}
	// We have tried all of our providers, noone could install this
	// extension, we just return failure at this point
	debug(reqInfo.name + " installation failed");
	return false;
	}

	/**
	* <p>
	* Checks if the extension, that is specified in the extension-list in
	* the applet jar manifest, is already installed (i.e. exists in the
	* extension directory).
	* </p>
	*
	* @param extensionName extension name in the extension-list
	*
	* @return the extension if it exists in the extension directory
	*/
	private File checkExtensionExists(String extensionName) {
	// Function added to fix bug 4504166
	final String extName = extensionName;
	final String[] fileExt = {".jar", ".zip"};

	return AccessController.doPrivileged(
	new PrivilegedAction<File>() {
	public File run() {
	try {
	File fExtension;
	File[] dirs = getExtDirs();

	// Search the extension directories for the extension that is specified
	// in the attribute extension-list in the applet jar manifest
	for (int i=0;i<dirs.length;i++) {
	for (int j=0;j<fileExt.length;j++) {
	if (extName.toLowerCase().endsWith(fileExt[j])) {
	fExtension = new File(dirs[i], extName);
	} else {
	fExtension = new File(dirs[i], extName+fileExt[j]);
	}
	debug("checkExtensionExists:fileName " + fExtension.getName());
	if (fExtension.exists()) {
	return fExtension;
	}
	}
	}
	return null;

	} catch(Exception e) {
	debugException(e);
	return null;
	}
	}
	});
	}

	/**
	* <p>
	* @return the java.ext.dirs property as a list of directory
	* </p>
	*/
	private static File[] getExtDirs() {
	String s = java.security.AccessController.doPrivileged(
	new sun.security.action.GetPropertyAction("java.ext.dirs"));

	File[] dirs;
	if (s != null) {
	StringTokenizer st =
	new StringTokenizer(s, File.pathSeparator);
	int count = st.countTokens();
	debug("getExtDirs count " + count);
	dirs = new File[count];
	for (int i = 0; i < count; i++) {
	dirs[i] = new File(st.nextToken());
	debug("getExtDirs dirs["+i+"] "+ dirs[i]);
	}
	} else {
	dirs = new File[0];
	debug("getExtDirs dirs " + dirs);
	}
	debug("getExtDirs dirs.length " + dirs.length);
	return dirs;
	}

	/*
	* <p>
	* Scan the directories and return all files installed in those
	* </p>
	* @param dirs list of directories to scan
	*
	* @return the list of files installed in all the directories
	*/
	private static File[] getExtFiles(File[] dirs) throws IOException {
	Vector<File> urls = new Vector<File>();
	for (int i = 0; i < dirs.length; i++) {
	String[] files = dirs[i].list(new JarFilter());
	if (files != null) {
	debug("getExtFiles files.length " + files.length);
	for (int j = 0; j < files.length; j++) {
	File f = new File(dirs[i], files[j]);
	urls.add(f);
	debug("getExtFiles f["+j+"] "+ f);
	}
	}
	}
	File[] ua = new File[urls.size()];
	urls.copyInto(ua);
	debug("getExtFiles ua.length " + ua.length);
	return ua;
	}

	/*
	* <p>
	* @return the list of installed extensions jar files
	* </p>
	*/
	private File[] getInstalledExtensions() throws IOException {
	return AccessController.doPrivileged(
	new PrivilegedAction<File[]>() {
	public File[] run() {
	try {
	return getExtFiles(getExtDirs());
	} catch(IOException e) {
	debug("Cannot get list of installed extensions");
	debugException(e);
	return new File[0];
	}
	}
	});
	}

	/*
	* <p>
	* Add the newly installed jar file to the extension class loader.
	* </p>
	*
	* @param cl the current installed extension class loader
	*
	* @return true if successful
	*/
	private Boolean addNewExtensionsToClassLoader(Launcher.ExtClassLoader cl) {
	try {
	File[] installedExts = getInstalledExtensions();
	for (int i=0;i<installedExts.length;i++) {
	final File instFile = installedExts[i];
	URL instURL = AccessController.doPrivileged(
	new PrivilegedAction<URL>() {
	public URL run() {
	try {
	return ParseUtil.fileToEncodedURL(instFile);
	} catch (MalformedURLException e) {
	debugException(e);
	return null;
	}
	}
	});
	if (instURL != null) {
	URL[] urls = cl.getURLs();
	boolean found=false;
	for (int j = 0; j<urls.length; j++) {
	debug("URL["+j+"] is " + urls[j] + " looking for "+
	instURL);
	if (urls[j].toString().compareToIgnoreCase(
	instURL.toString())==0) {
	found=true;
	debug("Found !");
	}
	}
	if (!found) {
	debug("Not Found ! adding to the classloader " +
	instURL);
	cl.addExtURL(instURL);
	}
	}
	}
	} catch (MalformedURLException e) {
	e.printStackTrace();
	} catch (IOException e) {
	e.printStackTrace();
	// let's continue with the next installed extension
	}
	return Boolean.TRUE;
	}

	// True to display all debug and trace messages
	static final boolean DEBUG = false;

	private static void debug(String s) {
	if (DEBUG) {
	System.err.println(s);
	}
	}

	private void debugException(Throwable e) {
	if (DEBUG) {
	e.printStackTrace();
	}
	}

	}