# MultiClassLoader.java

    /*
    ** Module   : MultiClassLoader.java
    ** Abstract : Provides a custom class loader which can manage multiple jars.
    **
    ** Copyright (c) 2011-2024, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- --------------------------------Description----------------------------------
    ** 001 CA  20111130 Initial version.
    ** 002 SVL 20130822 On construction this class loader creates InMemoryClassLoader as the parent.
    ** 003 CA  20140213 Added appendToClassPathForInstrumentation, to allow profilers to be added via
    **                  the Hot Spot VM.
    ** 004 ECF 20150413 Replaced InMemoryClassLoader with AsmClassLoader in the chain of delegates.
    ** 005 ECF 20150828 Javadoc cleanup.
    ** 006 IAS 20150403 Fixed managerLibsDir declaration and initialization.
    ** 007 VVT 20200924 Fixed: logging in class initialization section causes recursion,
    **                  See. #4527. Also some code polishing: missing annotations added etc.
    ** 008 SBI 20210414 Changed usages of JarClassLoader to simplify the code.
    ** 009 GBB 20230512 Logging methods replaced by CentralLogger/ConversionStatus.
    ** 010 GBB 20230517 Remove use of CentralLogger in static initializer.
    ** 011 GBB 20230825 checkCallerAbort moved to SecurityUtil & calls updated.
    ** 012 GBB 20240404 Methods resolveJarName and prettyName moved to JarUtil.
    **                  Static initializer code to JarUtil.resolveClasspathJars to be reused.
    **                  classpathJars type changed from Set to List.
    ** 013 ICP 20240704 Fixed findResource to ensure that the loaded jars are correctly searched.
    **     ICP 20240705 Added static method getClassLoader() to retrieve the MultiClassLoader
    **                  from the current thread's context class loader.
    **                  Fixed method of obtaining the class loader.
    */
    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
    **     publicity purposes without written authorization.
    **
    **   2. No Misrepresentation of Affiliation.
    **
    **     You may not represent yourself as Golden Code Development Corporation or FWD.
    **
    **     You may not represent yourself for publicity purposes as associated with
    **     Golden Code Development Corporation, FWD, or any author or contributor to
    **     the covered work, without written authorization.
    **
    **   3. No Misrepresentation of Source or Origin.
    **
    **     You may not represent the covered work as solely your work.  All modified
    **     versions of the covered work must be marked in a reasonable way to make it
    **     clear that the modified work is not originating from Golden Code Development
    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */

    package com.goldencode.p2j.classloader;

    import com.goldencode.asm.*;
    import com.goldencode.p2j.directory.*;
    import com.goldencode.p2j.security.*;
    import com.goldencode.p2j.util.*;
    import com.goldencode.p2j.util.logging.*;

    import java.io.*;
    import java.net.*;
    import java.util.*;
    import java.util.logging.*;

    /**
     * This class provides a container for managing class loaders for multiple
     * jars.  When determining the class loader for a file, first it searches for
     * a managed jar which handles that file.  If it was found, then it delegates
     * the request to it; else, it delegates the request to this class loader's
     * parent.
     * <p>
     * To use this class loader, set this property when starting the server:
     * <code>-Djava.system.class.loader=com.goldencode.p2j.classloader.MultiClassLoader</code>
     */
    public class MultiClassLoader
    extends ClassLoader
    {
       /** logger */
       private static final CentralLogger LOG = CentralLogger.get(MultiClassLoader.class.getName(), false, false);

       /** Map containing as key the jar name and as value its associated class loader. */
       private final Map<String, JarClassLoader> loaders = new HashMap<>();

       /** Map each class to the classloader which handles it. */
       private final Map<String, JarClassLoader> jclByClasses = new HashMap<>();

       /**
        * Managed customer libraries directory path. If <code>null</code> then
        * it hasn't been read yet, otherwise it is contained in the zero element
        * of the array.
        */
       private static volatile String managedLibsDir = null;

       /** A set containing all jars added to the classpath when the server was started. */
       private static final List<String> classpathJars = JarUtil.resolveClasspathJars(null);

       /**
        * C'tor. Instantiate the class loader by linking it with its parent.
        *
        * @param parent
        *        Parent class loader.
        */
       public MultiClassLoader(ClassLoader parent)
       {
          // class loaders will be chained: MultiClassLoader -> AsmClassLoader -> standard class
          // loader
          super(new AsmClassLoader(parent));
       }

       /**
        * Check if the given class is handled by a custom jar loader for the given
        * jar.
        *
        * @param   clazz
        *          The class object.
        * @param   jarName
        *          The jar name.
        *
        * @return  See above.
        */
       public static boolean handledByJar(Class<?> clazz, String jarName)
       {
          return handledByJar(clazz.getName(), jarName);
       }

       /**
        * Check if the given class is handled by a custom jar loader for the given
        * jar.
        *
        * @param   className
        *          The name of the class to be checked.
        * @param   jarName
        *          The jar name.
        *
        * @return  See above.
        */
       public static boolean handledByJar(String className, String jarName)
       {
          jarName = JarUtil.resolveJarName(LOG, jarName, false);
          if (jarName == null)
          {
             return false;
          }

          ClassLoader scl = getClassLoader();
          if (!(scl instanceof MultiClassLoader))
          {
             return false;
          }

          MultiClassLoader mcl = (MultiClassLoader) scl;

          JarClassLoader jcl;
          synchronized (mcl)
          {
             jcl = mcl.loaders.get(jarName);
          }

          if (jcl != null)
          {
             return jcl.containsClass(className);
          }

          return false;
       }

       /**
        * Register the given jar to be handled by its own class loader.
        *
        * @param   jarName
        *          The jar name.
        *
        * @return  {@link ErrorCode#SUCCESS} if the loading was done. Else,
        *          it returns an {@link ErrorCode error code}.
        *
        * @throws  RestrictedUseException
        *          if called improperly.
        */
       public static ErrorCode addJarLoader(String jarName)
       throws RestrictedUseException
       {
          SecurityUtil.checkCallerAbort(new String[]{
                "com.goldencode.p2j.admin.AdminServerImpl.registerJar",
                "com.goldencode.p2j.main.StandardServer.initClassLoaders"},
                "com.goldencode.p2j.classloader.MultiClassLoader");

          ClassLoader scl = getClassLoader();
          if (!(scl instanceof MultiClassLoader))
          {
             return ErrorCode.BAD_LOADER;
          }

          return ((MultiClassLoader) scl).addJarLoaderImpl(jarName, false);
       }

       /**
        * Remove the classloader associated with the given jar.
        *
        * @param   jarName
        *          The jar name.
        *
        * @return  {@link ErrorCode#SUCCESS} if the deregistration was done. Else,
        *          it returns an {@link ErrorCode error code}.
        *
        * @throws  RestrictedUseException
        *          if called improperly.
        */
       public static ErrorCode removeJarLoader(String jarName)
       throws RestrictedUseException
       {
          SecurityUtil.checkCallerAbort(new String[]{
                "com.goldencode.p2j.admin.AdminServerImpl.registerJar",
                "com.goldencode.p2j.admin.AdminServerImpl.deregisterJar"},
                "com.goldencode.p2j.classloader.MultiClassLoader");

          ClassLoader scl = getClassLoader();
          if (!(scl instanceof MultiClassLoader))
          {
             return ErrorCode.BAD_LOADER;
          }

          return ((MultiClassLoader) scl).removeJarLoaderImpl(jarName);
       }

       /**
        * Get the managed customer libs folder. First, it checks managed.libs.dir
        * system property, then, as a fallback, it checks the configuration
        * directory (path is <code>/server/default/managed-libs-dir</code> or
        * <code>/server/&lt;serverID&gt;/managed-libs-dir</code>).
        *
        * @return   managed customer libs folder or <code>null</code> if it is not
        *           specified.
        */
       public static String managedCustomerLibs()
       {
          // quick check
          if (managedLibsDir == null)
          {
             synchronized (MultiClassLoader.class)
             {
                if (managedLibsDir == null)
                {
                   String cl = System.getProperty("managed.libs.dir", null);

                   if (cl == null)
                   {
                      DirectoryService ds = DirectoryService.getInstance();
                      cl = Utils.getDirectoryNodeString(ds,
                                                        "managed-libs-dir",
                                                        null,
                                                        false);
                   }

                   if (cl != null && !cl.endsWith(File.separator))
                   {
                      cl = cl + File.separator;
                   }

                   managedLibsDir = cl;
                }
             }
          }
          return managedLibsDir;
       }

       /**
        * List all classes in the given jar. The classes will not be initialized.
        *
        * @param   jarName
        *          The jar name.
        *
        * @return  The list of classes in this jar or <code>null</code> in case
        *          of error.
        */
       public static ClassInfo[] listClasses(String jarName)
       {
          ClassLoader cl = getClassLoader();
          jarName = JarUtil.resolveJarName(LOG, jarName, false);

          if (jarName == null || !(cl instanceof MultiClassLoader))
          {
             return null;
          }

          MultiClassLoader  mcl = (MultiClassLoader) cl;

          JarClassLoader jcl;
          synchronized (mcl)
          {
             jcl = mcl.loaders.get(jarName);
          }

          if (jcl != null)
          {
             // jar is already loaded
             return jcl.listClasses();
          }

          // load jar, get the list of classes, close jar
          JarClassLoader loader = JarClassLoader.createJarClassLoader(jarName, cl.getParent());
          if (loader == null)
          {
             return null;
          }

          ClassInfo[] res = null;
          try
          {
             res = loader.listClasses();
          }
          finally
          {
             loader.closeLoader();
          }
          return res;
       }

       /**
        * List the jars handled by custom class loaders.
        *
        * @return   See above.
        */
       public static String[] listRegisteredJars()
       {
          ClassLoader cl = getClassLoader();
          if (!(cl instanceof MultiClassLoader))
          {
             return new String[0];
          }

          MultiClassLoader mcl = (MultiClassLoader) cl;
          Set<String> names = new TreeSet<>();

          synchronized (mcl)
          {
             for (String name : mcl.loaders.keySet())
             {
                names.add(JarUtil.prettyName(name));
             }
          }

          return names.toArray(new String[0]);
       }

       /**
        * List the jars which may be handled by custom class loaders (they reside
        * in the given path, are not yet handled by custom class loaders and are
        * not in the classpath).
        * <p>
        * The unregistered jars are searched in the customer_libs property
        * specified at server startup. If it was not specified, then it will
        * return an empty list.
        *
        * @return   See above.
        */
       public static String[] listUnregisteredJars()
       {
          String customerLibs = managedCustomerLibs();
          if (customerLibs == null)
             return new String[0];

          File f = new File(customerLibs);
          ClassLoader cl = getClassLoader();

          if (!(cl instanceof MultiClassLoader) ||
              !f.exists()                       ||
              !f.isDirectory())
          {
             return new String[0];
          }

          MultiClassLoader mcl = (MultiClassLoader) cl;
          Set<String> registered;
          synchronized (mcl)
          {
             registered = new TreeSet<>(mcl.loaders.keySet());
          }

          Set<String> unregs = new TreeSet<>();

          File[] files = f.listFiles();
          for (File file : files)
          {
             String name = file.getPath();
             String jarName = JarUtil.resolveJarName(LOG, name, true);

             if (file.isDirectory()               ||
                 !file.getName().endsWith(".jar") ||
                 classpathJars.contains(jarName)  ||
                 registered.contains(jarName))
             {
                continue;
             }

             unregs.add(JarUtil.prettyName(name));
          }

          return unregs.toArray(new String[unregs.size()]);
       }

       /**
        * Finds the resource with the given name. First it searches the loaded
        * jars; if not found, delegates the search to the parent class loader.
        *
        * @param   name
        *          The resource name
        *
        * @return  A <tt>URL</tt> object for reading the resource, or
        *          <tt>null</tt> if the resource could not be found
        */
       @Override
       protected synchronized URL findResource(String name)
       {
          if (LOG.isLoggable(Level.FINE))
          {
             LOG.log(Level.FINE, "Searching for resource " + name);
          }

          // search in loaders first
          URL url = null;

          for (String pathToJar : classpathJars)
          {
             JarClassLoader jcl = loaders.get(pathToJar);
             if (jcl != null && jcl.containsResource(name))
             {
                url = jcl.getResource(name);
                break;
             }
          }

          // delegate to parent if not found
          return url == null ? getParent().getResource(name) : url;
       }

       /**
        * Find and load the class with the given name. If this is in one of the
        * registered Jar class loaders, it will delegate the loading to it. Else,
        * the search is delegated to the parent class loader.
        *
        * @return  The {@link Class} object.
        *
        * @throws  ClassNotFoundException
        *          If the class can not be found or class linkage has error
        *          occurred.
        */
       @Override
       protected Class<?> findClass(String name)
       throws ClassNotFoundException
       {
          if (LOG.isLoggable(Level.FINE))
          {
             LOG.log(Level.FINE, "Searching for class " + name);
          }

          Class<?> clazz = getClass(name);

          try
          {
             return clazz == null ? super.findClass(name) : clazz;
          }
          catch (NoClassDefFoundError e)
          {
             throw new ClassNotFoundException("Linkage error for class " + name,
                                              e);
          }
       }

       /**
        * Find and load the class with the given name. If this is in one of the
        * registered Jar class loaders, it will delegate the loading to it. Else,
        * the search is delegated to the parent class loader.
        *
        * @return  The {@link Class} object.
        *
        * @throws  ClassNotFoundException
        *          If the class can not be found or class linkage has error
        *          occurred.
        */
       @Override
       public Class<?> loadClass(String name)
       throws ClassNotFoundException
       {
          if (LOG.isLoggable(Level.FINE))
          {
             LOG.log(Level.FINE, "Loading class " + name);
          }

          try
          {
             Class<?> clazz;
             try
             {
                clazz = getParent().loadClass(name);
             }
             catch (ClassNotFoundException e)
             {
                clazz = findClass(name);
             }

             return clazz == null ? super.loadClass(name) : clazz;
          }
          catch (NoClassDefFoundError e)
          {
             throw new ClassNotFoundException("Linkage error for class " + name,
                                              e);
          }
       }

       /**
        * Find and load the class with the given name. If this is in one of the
        * registered Jar class loaders, it will delegate the loading to it. Else,
        * the search is delegated to the parent class loader.
        *
        * @param    name
        *           The class name
        *
        * @return   The {@link Class} object, or <code>null</code> if this class
        *           does not belong to any of the registered jars.
        *
        * @throws   ClassNotFoundException
        *           If the class belongs must be handled by a {@link JarClassLoader}
        *           but can not be loaded.
        */
       public synchronized Class<?> getClass(String name)
       throws ClassNotFoundException
       {
          JarClassLoader jcl = jclByClasses.get(name);

          if (jcl == null)
          {
             // check the jar loaders

             for (String pathToJar : loaders.keySet())
             {
                JarClassLoader jar = loaders.get(pathToJar);
                if (jar != null && jar.containsClass(name))
                {
                   if (jcl != null)
                   {
                      // class found in more than one jar, log inf
                      String jar1 = jar.getJarName();
                      String jar2 = jcl.getJarName();

                      // JVM says that only the first returned reference is
                      // handled - if more, I don't care
                      if (LOG.isLoggable(Level.WARNING))
                      {
                         LOG.warning("Class " + name +
                                     " is defined in both " +
                                     jar1 + " and " + jar2 + " jars !");
                      }

                      break;
                   }

                   jcl = jar;
                }
             }

             if (jcl != null)
             {
                jclByClasses.put(name, jcl);
             }
          }

          return jcl == null ? null : jcl.loadClass(name);
       }

       /**
        * To support dynamic additions to the class path at runtime, the class loader needs to define
        * this private method. This will be invoked from the native VM code, to load a jar.
        * <p>
        * This method does not have to be public.
        *
        * @param    path
        *           The full path of the jar to be appended.
        */
       @SuppressWarnings("unused")
       private void appendToClassPathForInstrumentation(String path)
       {
          addJarLoaderImpl(path, true);
       }

       /**
        * Register the given jar to be handled by its own class loader.
        *
        * @param   jarName
        *          The jar name.
        * @param   fullPath
        *          <code>true</code> if the <code>jarName</code> contains also
        *          the jar's path.  When <code>false</code>, it is assumed that
        *          the path is the one specified in the "customer_libs" system
        *          property.
        *
        * @return  {@link ErrorCode#SUCCESS} if the loading was done. Else,
        *          it returns an {@link ErrorCode error code}.
        */
       private synchronized ErrorCode addJarLoaderImpl(String jarName, boolean fullPath)
       {
          jarName = JarUtil.resolveJarName(LOG, jarName, fullPath);
          if (jarName == null)
          {
             return ErrorCode.NOT_FOUND;
          }

          if (classpathJars.contains(jarName))
          {
             if (LOG.isLoggable(Level.INFO))
             {
                LOG.log(Level.INFO,
                        "Could not add jar loader for jar " + jarName +
                        " - it is already added to classpath.");
             }

             return ErrorCode.IN_CLASSPATH;
          }

          if (LOG.isLoggable(Level.INFO))
          {
             LOG.log(Level.INFO,
                     "Adding jar loader for jar " + jarName);
          }

          if (loaders.containsKey(jarName))
          {
             // jar already loaded, must remove first
             if (LOG.isLoggable(Level.WARNING))
             {
                LOG.log(Level.WARNING,
                        "Jar loader for jar " + jarName +
                        "is already loaded - it will be removed before adding.");
             }
             ErrorCode er = removeJarLoaderImpl(jarName);
             if (er != ErrorCode.SUCCESS)
             {
                return er;
             }
          }

          JarClassLoader loader = JarClassLoader.getOrCreateCachedJarClassLoader(jarName, getParent());
          if (loader != null)
          {
             loaders.put(jarName, loader);
          }
          else
          {
             // jar can not be initialized
             if (LOG.isLoggable(Level.SEVERE))
             {
                LOG.log(Level.SEVERE,
                        "Could not initialize loader for jar " + jarName);
             }

             return ErrorCode.INIT_ERROR;
          }

          return ErrorCode.SUCCESS;
       }

       /**
        * Remove the classloader associated with the given jar.
        *
        * @param   jarName
        *          The jar name.
        *
        * @return  {@link ErrorCode#SUCCESS} if the deregistration was done. Else,
        *          it returns an {@link ErrorCode error code}.
        */
       private synchronized ErrorCode removeJarLoaderImpl(String jarName)
       {
          jarName = JarUtil.resolveJarName(LOG, jarName, false);
          if (jarName == null)
          {
             return ErrorCode.NOT_FOUND;
          }

          if (LOG.isLoggable(Level.INFO))
          {
             LOG.log(Level.INFO, "Removing jar loader for jar " + jarName);
          }

          JarClassLoader jar = loaders.get(jarName);
          if (jar == null)
          {
             // jar can not be found
             if (LOG.isLoggable(Level.WARNING))
             {
                LOG.log(Level.WARNING,
                        "Can not remove jar loader for jar " + jarName +
                        ": the jar is not registered with a class loader !");
             }

             return ErrorCode.NOT_REGISTERED;
          }

          if (!jar.closeLoader())
          {
             // jar can not be closed
             return ErrorCode.CLOSE_ERROR;
          }
          loaders.remove(jarName);

          // remove all cached classes
          Iterator<JarClassLoader> itr = jclByClasses.values().iterator();
          while (itr.hasNext())
          {
             JarClassLoader jcl = itr.next();
             if (jcl == jar)
                itr.remove();
          }

          return ErrorCode.SUCCESS;
       }

       /**
        * Utility method to obtain the MultiClassLoader instance from the current thread's context
        * class loader. If no MultiClassLoader is found in the thread hierarchy, it returns the
        * system class loader.
        *
        * @return  The MultiClassLoader instance if found, otherwise the system class loader.
        */
       public static ClassLoader getClassLoader()
       {
          ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
          while (!(classLoader instanceof MultiClassLoader) &&
                 classLoader.getParent() != null)
          {
             classLoader = classLoader.getParent();
          }
          if (!(classLoader instanceof MultiClassLoader))
          {
             classLoader = ClassLoader.getSystemClassLoader();
          }
          return classLoader;
       }
    }