349 lines
11 KiB
Java
349 lines
11 KiB
Java
/* VMClassLoader.java -- Reference implementation of native interface
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required by ClassLoader
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Copyright (C) 1998, 2001, 2002, 2003, 2004, 2005 Free Software Foundation
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.lang;
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import gnu.java.util.EmptyEnumeration;
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import java.lang.reflect.Constructor;
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import java.io.File;
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import java.io.IOException;
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import java.net.URL;
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import java.net.URLClassLoader;
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import java.security.AllPermission;
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import java.security.Permission;
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import java.security.Permissions;
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import java.security.ProtectionDomain;
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import java.util.ArrayList;
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import java.util.Enumeration;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.Map;
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import java.util.StringTokenizer;
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import gnu.gcj.runtime.BootClassLoader;
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/**
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* java.lang.VMClassLoader is a package-private helper for VMs to implement
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* on behalf of java.lang.ClassLoader.
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*
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* @author John Keiser
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* @author Mark Wielaard <mark@klomp.org>
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* @author Eric Blake <ebb9@email.byu.edu>
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*/
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final class VMClassLoader
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{
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// Protection Domain definitions
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// FIXME: should there be a special protection domain used for native code?
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// The permission required to check what a classes protection domain is.
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static final Permission protectionDomainPermission
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= new RuntimePermission("getProtectionDomain");
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// The protection domain returned if we cannot determine it.
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static ProtectionDomain unknownProtectionDomain;
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static
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{
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Permissions permissions = new Permissions();
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permissions.add(new AllPermission());
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unknownProtectionDomain = new ProtectionDomain(null, permissions);
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}
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static final HashMap definedPackages = new HashMap();
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// This is a helper for handling java.endorsed.dirs. It is null
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// until we've initialized the system, at which point it is created.
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static BootClassLoader bootLoader;
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// This keeps track of shared libraries we've already tried to load.
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private static HashSet tried_libraries;
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// Holds one of the LIB_* constants; used to determine how shared
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// library loads are done.
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private static int lib_control;
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private static final int LIB_FULL = 0;
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private static final int LIB_CACHE = 1;
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private static final int LIB_NEVER = 2;
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/**
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* Helper to define a class using a string of bytes. This assumes that
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* the security checks have already been performed, if necessary.
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*
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* <strong>For backward compatibility, this just ignores the protection
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* domain; that is the wrong behavior, and you should directly implement
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* this method natively if you can.</strong>
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*
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* @param name the name to give the class, or null if unknown
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* @param data the data representing the classfile, in classfile format
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* @param offset the offset into the data where the classfile starts
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* @param len the length of the classfile data in the array
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* @param pd the protection domain
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* @return the class that was defined
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* @throws ClassFormatError if data is not in proper classfile format
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*/
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static final native Class defineClass(ClassLoader cl, String name,
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byte[] data, int offset, int len,
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ProtectionDomain pd)
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throws ClassFormatError;
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/**
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* Helper to resolve all references to other classes from this class.
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*
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* @param c the class to resolve
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*/
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static final void resolveClass(Class clazz)
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{
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// There doesn't seem to be a need for this to do anything.
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// Testing reveals that the JDK doesn't seem to do anything here,
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// either.
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}
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/**
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* Helper to load a class from the bootstrap class loader.
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*
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* @param name the class name to load
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* @param resolve whether to resolve it
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* @return the class, loaded by the bootstrap classloader or null
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* if the class wasn't found. Returning null is equivalent to throwing
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* a ClassNotFoundException (but a possible performance optimization).
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*/
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static final native Class loadClass(String name, boolean resolve)
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throws ClassNotFoundException;
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/**
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* Helper to load a resource from the bootstrap class loader.
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*
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* In libgcj, this does nothing, as the default system loader knows
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* how to find resources that have been linked in.
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*
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* @param name the resource to find
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* @return the URL to the resource
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*/
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static URL getResource(String name)
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{
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if (bootLoader != null)
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return bootLoader.bootGetResource(name);
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return null;
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}
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/**
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* Helper to get a list of resources from the bootstrap class loader.
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*
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* In libgcj, this does nothing, as the default system loader knows
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* how to find resources that have been linked in.
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*
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* @param name the resource to find
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* @return an enumeration of resources
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* @throws IOException if one occurs
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*/
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static Enumeration getResources(String name) throws IOException
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{
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if (bootLoader != null)
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return bootLoader.bootGetResources(name);
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return EmptyEnumeration.getInstance();
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}
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/**
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* Helper to get a package from the bootstrap class loader. The default
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* implementation of returning null may be adequate, or you may decide
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* that this needs some native help.
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*
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* @param name the name to find
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* @return the named package, if it exists
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*/
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static synchronized Package getPackage(String name)
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{
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return (Package) definedPackages.get(name);
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}
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/**
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* Helper to get all packages from the bootstrap class loader. The default
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* implementation of returning an empty array may be adequate, or you may
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* decide that this needs some native help.
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*
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* @return all named packages, if any exist
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*/
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static synchronized Package[] getPackages()
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{
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Package[] packages = new Package[definedPackages.size()];
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return (Package[]) definedPackages.values().toArray(packages);
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}
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// Define a package for something loaded natively.
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static synchronized void definePackageForNative(String className)
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{
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int lastDot = className.lastIndexOf('.');
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if (lastDot != -1)
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{
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String packageName = className.substring(0, lastDot);
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if (getPackage(packageName) == null)
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{
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// FIXME: this assumes we're defining the core, which
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// isn't necessarily so. We could detect this and set up
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// appropriately. We could also look at a manifest file
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// compiled into the .so.
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Package p = new Package(packageName,
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"Java Platform API Specification",
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"GNU", "1.4", "gcj", "GNU",
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null, // FIXME: gcj version.
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null);
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definedPackages.put(packageName, p);
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}
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}
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}
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/**
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* Helper for java.lang.Integer, Byte, etc to get the TYPE class
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* at initialization time. The type code is one of the chars that
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* represents the primitive type as in JNI.
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*
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* <ul>
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* <li>'Z' - boolean</li>
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* <li>'B' - byte</li>
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* <li>'C' - char</li>
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* <li>'D' - double</li>
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* <li>'F' - float</li>
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* <li>'I' - int</li>
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* <li>'J' - long</li>
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* <li>'S' - short</li>
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* <li>'V' - void</li>
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* </ul>
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*
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* @param type the primitive type
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* @return a "bogus" class representing the primitive type
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*/
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static final native Class getPrimitiveClass(char type);
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/**
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* The system default for assertion status. This is used for all system
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* classes (those with a null ClassLoader), as well as the initial value for
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* every ClassLoader's default assertion status.
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*
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* XXX - Not implemented yet; this requires native help.
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*
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* @return the system-wide default assertion status
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*/
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static final boolean defaultAssertionStatus()
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{
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return true;
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}
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/**
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* The system default for package assertion status. This is used for all
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* ClassLoader's packageAssertionStatus defaults. It must be a map of
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* package names to Boolean.TRUE or Boolean.FALSE, with the unnamed package
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* represented as a null key.
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*
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* XXX - Not implemented yet; this requires native help.
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*
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* @return a (read-only) map for the default packageAssertionStatus
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*/
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static final Map packageAssertionStatus()
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{
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return new HashMap();
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}
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/**
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* The system default for class assertion status. This is used for all
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* ClassLoader's classAssertionStatus defaults. It must be a map of
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* class names to Boolean.TRUE or Boolean.FALSE
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*
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* XXX - Not implemented yet; this requires native help.
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*
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* @return a (read-only) map for the default classAssertionStatus
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*/
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static final Map classAssertionStatus()
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{
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return new HashMap();
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}
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static native ClassLoader getSystemClassLoaderInternal();
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static native void initBootLoader(String libdir);
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static void initialize(String libdir)
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{
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initBootLoader(libdir);
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String p
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= System.getProperty ("gnu.gcj.runtime.VMClassLoader.library_control",
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"");
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if ("never".equals(p))
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lib_control = LIB_NEVER;
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else if ("cache".equals(p))
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lib_control = LIB_CACHE;
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else if ("full".equals(p))
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lib_control = LIB_FULL;
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else
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lib_control = LIB_CACHE;
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tried_libraries = new HashSet();
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}
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/**
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* Possibly load a .so and search it for classes.
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*/
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static native Class nativeFindClass(String name);
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static ClassLoader getSystemClassLoader()
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{
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// This method is called as the initialization of systemClassLoader,
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// so if there is a null value, this is the first call and we must check
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// for java.system.class.loader.
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String loader = System.getProperty("java.system.class.loader");
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ClassLoader default_sys = getSystemClassLoaderInternal();
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if (loader != null)
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{
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try
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{
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Class load_class = Class.forName(loader, true, default_sys);
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Constructor c
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= load_class.getConstructor(new Class[] { ClassLoader.class });
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default_sys
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= (ClassLoader) c.newInstance(new Object[] { default_sys });
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}
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catch (Exception ex)
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{
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throw new Error("Failed to load requested system classloader "
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+ loader, ex);
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}
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}
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return default_sys;
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}
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}
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