libjava/java/lang/VMClassLoader.java

   1 /* VMClassLoader.java -- Reference implementation of native interface
   2    required by ClassLoader
   3    Copyright (C) 1998, 2001, 2002, 2003, 2004, 2005 Free Software Foundation
   4
   5 This file is part of GNU Classpath.
   6
   7 GNU Classpath is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU Classpath is distributed in the hope that it will be useful, but
  13 WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15 General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Classpath; see the file COPYING.  If not, write to the
  19 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  20 02111-1307 USA.
  21
  22 Linking this library statically or dynamically with other modules is
  23 making a combined work based on this library.  Thus, the terms and
  24 conditions of the GNU General Public License cover the whole
  25 combination.
  26
  27 As a special exception, the copyright holders of this library give you
  28 permission to link this library with independent modules to produce an
  29 executable, regardless of the license terms of these independent
  30 modules, and to copy and distribute the resulting executable under
  31 terms of your choice, provided that you also meet, for each linked
  32 independent module, the terms and conditions of the license of that
  33 module.  An independent module is a module which is not derived from
  34 or based on this library.  If you modify this library, you may extend
  35 this exception to your version of the library, but you are not
  36 obligated to do so.  If you do not wish to do so, delete this
  37 exception statement from your version. */
  38
  39 package java.lang;
  40
  41 import gnu.java.util.EmptyEnumeration;
  42 import java.lang.reflect.Constructor;
  43 import java.io.File;
  44 import java.io.IOException;
  45 import java.net.URL;
  46 import java.net.URLClassLoader;
  47 import java.security.AllPermission;
  48 import java.security.Permission;
  49 import java.security.Permissions;
  50 import java.security.ProtectionDomain;
  51 import java.util.ArrayList;
  52 import java.util.Enumeration;
  53 import java.util.HashMap;
  54 import java.util.HashSet;
  55 import java.util.Map;
  56 import java.util.StringTokenizer;
  57 import gnu.gcj.runtime.BootClassLoader;
  58
  59 /**
  60  * java.lang.VMClassLoader is a package-private helper for VMs to implement
  61  * on behalf of java.lang.ClassLoader.
  62  *
  63  * @author John Keiser
  64  * @author Mark Wielaard <mark@klomp.org>
  65  * @author Eric Blake <ebb9@email.byu.edu>
  66  */
  67 final class VMClassLoader
  68 {
  69   // Protection Domain definitions
  70   // FIXME: should there be a special protection domain used for native code?
  71
  72   // The permission required to check what a classes protection domain is.
  73   static final Permission protectionDomainPermission
  74     = new RuntimePermission("getProtectionDomain");
  75   // The protection domain returned if we cannot determine it.
  76   static ProtectionDomain unknownProtectionDomain;
  77
  78   static
  79   {
  80     Permissions permissions = new Permissions();
  81     permissions.add(new AllPermission());
  82     unknownProtectionDomain = new ProtectionDomain(null, permissions);
  83   }
  84
  85   static final HashMap definedPackages = new HashMap();
  86
  87   // This is a helper for handling java.endorsed.dirs.  It is null
  88   // until we've initialized the system, at which point it is created.
  89   static BootClassLoader bootLoader;
  90
  91   // This keeps track of shared libraries we've already tried to load.
  92   private static HashSet tried_libraries;
  93
  94   // Holds one of the LIB_* constants; used to determine how shared
  95   // library loads are done.
  96   private static int lib_control;
  97
  98   private static final int LIB_FULL = 0;
  99   private static final int LIB_CACHE = 1;
 100   private static final int LIB_NEVER = 2;
 101
 102   /**
 103    * Helper to define a class using a string of bytes. This assumes that
 104    * the security checks have already been performed, if necessary.
 105    *
 106    * <strong>For backward compatibility, this just ignores the protection
 107    * domain; that is the wrong behavior, and you should directly implement
 108    * this method natively if you can.</strong>
 109    *
 110    * @param name the name to give the class, or null if unknown
 111    * @param data the data representing the classfile, in classfile format
 112    * @param offset the offset into the data where the classfile starts
 113    * @param len the length of the classfile data in the array
 114    * @param pd the protection domain
 115    * @return the class that was defined
 116    * @throws ClassFormatError if data is not in proper classfile format
 117    */
 118   static final native Class defineClass(ClassLoader cl, String name,
 119                                         byte[] data, int offset, int len,
 120                                         ProtectionDomain pd)
 121     throws ClassFormatError;
 122
 123   /**
 124    * Helper to resolve all references to other classes from this class.
 125    *
 126    * @param c the class to resolve
 127    */
 128   static final native void resolveClass(Class clazz);
 129
 130   static final void transformException(Class clazz, Throwable x)
 131   {
 132     LinkageError e;
 133     if (x instanceof LinkageError)
 134       e = (LinkageError) x;
 135     else if (x instanceof ClassNotFoundException)
 136       {
 137         e = new NoClassDefFoundError("while resolving class: "
 138                                      + clazz.getName());
 139         e.initCause (x);
 140       }
 141     else
 142       {
 143         e = new LinkageError ("unexpected exception during linking: "
 144                               + clazz.getName());
 145         e.initCause (x);
 146       }
 147     throw e;
 148   }
 149
 150   /**
 151    * Helper to load a class from the bootstrap class loader.
 152    *
 153    * @param name the class name to load
 154    * @param resolve whether to resolve it
 155    * @return the class, loaded by the bootstrap classloader or null
 156    * if the class wasn't found. Returning null is equivalent to throwing
 157    * a ClassNotFoundException (but a possible performance optimization).
 158    */
 159   static final native Class loadClass(String name, boolean resolve)
 160     throws ClassNotFoundException;
 161
 162   /**
 163    * Helper to load a resource from the bootstrap class loader.
 164    *
 165    * In libgcj, this does nothing, as the default system loader knows
 166    * how to find resources that have been linked in.
 167    *
 168    * @param name the resource to find
 169    * @return the URL to the resource
 170    */
 171   static URL getResource(String name)
 172   {
 173     if (bootLoader != null)
 174       return bootLoader.bootGetResource(name);
 175     return null;
 176   }
 177
 178   /**
 179    * Helper to get a list of resources from the bootstrap class loader.
 180    *
 181    * In libgcj, this does nothing, as the default system loader knows
 182    * how to find resources that have been linked in.
 183    *
 184    * @param name the resource to find
 185    * @return an enumeration of resources
 186    * @throws IOException if one occurs
 187    */
 188   static Enumeration getResources(String name) throws IOException
 189   {
 190     if (bootLoader != null)
 191       return bootLoader.bootGetResources(name);
 192     return EmptyEnumeration.getInstance();
 193   }
 194
 195   /**
 196    * Helper to get a package from the bootstrap class loader.  The default
 197    * implementation of returning null may be adequate, or you may decide
 198    * that this needs some native help.
 199    *
 200    * @param name the name to find
 201    * @return the named package, if it exists
 202    */
 203   static synchronized Package getPackage(String name)
 204   {
 205     return (Package) definedPackages.get(name);
 206   }
 207
 208   /**
 209    * Helper to get all packages from the bootstrap class loader.  The default
 210    * implementation of returning an empty array may be adequate, or you may
 211    * decide that this needs some native help.
 212    *
 213    * @return all named packages, if any exist
 214    */
 215   static synchronized Package[] getPackages()
 216   {
 217     Package[] packages = new Package[definedPackages.size()];
 218     return (Package[]) definedPackages.values().toArray(packages);
 219   }
 220
 221   // Define a package for something loaded natively.
 222   static synchronized void definePackageForNative(String className)
 223   {
 224     int lastDot = className.lastIndexOf('.');
 225     if (lastDot != -1)
 226       {
 227         String packageName = className.substring(0, lastDot);
 228         if (getPackage(packageName) == null)
 229           {
 230             // FIXME: this assumes we're defining the core, which
 231             // isn't necessarily so.  We could detect this and set up
 232             // appropriately.  We could also look at a manifest file
 233             // compiled into the .so.
 234             Package p = new Package(packageName,
 235                                     "Java Platform API Specification",
 236                                     "GNU", "1.4", "gcj", "GNU",
 237                                     null, // FIXME: gcj version.
 238                                     null);
 239             definedPackages.put(packageName, p);
 240           }
 241       }
 242   }
 243
 244   /**
 245    * Helper for java.lang.Integer, Byte, etc to get the TYPE class
 246    * at initialization time. The type code is one of the chars that
 247    * represents the primitive type as in JNI.
 248    *
 249    * <ul>
 250    * <li>'Z' - boolean</li>
 251    * <li>'B' - byte</li>
 252    * <li>'C' - char</li>
 253    * <li>'D' - double</li>
 254    * <li>'F' - float</li>
 255    * <li>'I' - int</li>
 256    * <li>'J' - long</li>
 257    * <li>'S' - short</li>
 258    * <li>'V' - void</li>
 259    * </ul>
 260    *
 261    * @param type the primitive type
 262    * @return a "bogus" class representing the primitive type
 263    */
 264   static final native Class getPrimitiveClass(char type);
 265
 266   /**
 267    * The system default for assertion status. This is used for all system
 268    * classes (those with a null ClassLoader), as well as the initial value for
 269    * every ClassLoader's default assertion status.
 270    *
 271    * XXX - Not implemented yet; this requires native help.
 272    *
 273    * @return the system-wide default assertion status
 274    */
 275   static final boolean defaultAssertionStatus()
 276   {
 277     return true;
 278   }
 279
 280   /**
 281    * The system default for package assertion status. This is used for all
 282    * ClassLoader's packageAssertionStatus defaults. It must be a map of
 283    * package names to Boolean.TRUE or Boolean.FALSE, with the unnamed package
 284    * represented as a null key.
 285    *
 286    * XXX - Not implemented yet; this requires native help.
 287    *
 288    * @return a (read-only) map for the default packageAssertionStatus
 289    */
 290   static final Map packageAssertionStatus()
 291   {
 292     return new HashMap();
 293   }
 294
 295   /**
 296    * The system default for class assertion status. This is used for all
 297    * ClassLoader's classAssertionStatus defaults. It must be a map of
 298    * class names to Boolean.TRUE or Boolean.FALSE
 299    *
 300    * XXX - Not implemented yet; this requires native help.
 301    *
 302    * @return a (read-only) map for the default classAssertionStatus
 303    */
 304   static final Map classAssertionStatus()
 305   {
 306     return new HashMap();
 307   }
 308
 309   static native ClassLoader getSystemClassLoaderInternal();
 310
 311   static native void initBootLoader(String libdir);
 312
 313   static void initialize(String libdir)
 314   {
 315     initBootLoader(libdir);
 316
 317     String p
 318       = System.getProperty ("gnu.gcj.runtime.VMClassLoader.library_control",
 319                             "");
 320     if ("never".equals(p))
 321       lib_control = LIB_NEVER;
 322     else if ("cache".equals(p))
 323       lib_control = LIB_CACHE;
 324     else if ("full".equals(p))
 325       lib_control = LIB_FULL;
 326     else
 327       lib_control = LIB_CACHE;
 328
 329     tried_libraries = new HashSet();
 330   }
 331
 332   /**
 333    * Possibly load a .so and search it for classes.
 334    */
 335   static native Class nativeFindClass(String name);
 336
 337   static ClassLoader getSystemClassLoader()
 338   {
 339     // This method is called as the initialization of systemClassLoader,
 340     // so if there is a null value, this is the first call and we must check
 341     // for java.system.class.loader.
 342     String loader = System.getProperty("java.system.class.loader");
 343     ClassLoader default_sys = getSystemClassLoaderInternal();
 344     if (loader != null)
 345       {
 346         try
 347           {
 348             Class load_class = Class.forName(loader, true, default_sys);
 349             Constructor c
 350               = load_class.getConstructor(new Class[] { ClassLoader.class });
 351             default_sys
 352               = (ClassLoader) c.newInstance(new Object[] { default_sys });
 353           }
 354         catch (Exception ex)
 355           {
 356             throw new Error("Failed to load requested system classloader "
 357                                + loader, ex);
 358           }
 359       }
 360
 361     return default_sys;
 362   }
 363 }