gcc/libjava/java/lang/natClassLoader.cc

// natClassLoader.cc - Implementation of java.lang.ClassLoader native methods.

/* Copyright (C) 1999, 2000  Cygnus Solutions

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the
Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
details.  */

/* Author: Kresten Krab Thorup <krab@gnu.org>  */

#include <config.h>

#include <stdlib.h>
#include <string.h>

#include <gcj/cni.h>
#include <jvm.h>

#include <java-threads.h>
#include <java-interp.h>

#include <java/lang/Character.h>
#include <java/lang/Thread.h>
#include <java/lang/ClassLoader.h>
#include <gnu/gcj/runtime/VMClassLoader.h>
#include <java/lang/InternalError.h>
#include <java/lang/IllegalAccessError.h>
#include <java/lang/LinkageError.h>
#include <java/lang/ClassFormatError.h>
#include <java/lang/NoClassDefFoundError.h>
#include <java/lang/ClassNotFoundException.h>
#include <java/lang/ClassCircularityError.h>
#include <java/lang/IncompatibleClassChangeError.h>
#include <java/lang/reflect/Modifier.h>

#define CloneableClass _CL_Q34java4lang9Cloneable
extern java::lang::Class CloneableClass;
#define ObjectClass _CL_Q34java4lang6Object
extern java::lang::Class ObjectClass;
#define ClassClass _CL_Q34java4lang5Class
extern java::lang::Class ClassClass;
#define VMClassLoaderClass _CL_Q34java4lang17VMClassLoader
extern java::lang::Class VMClassLoader;
#define ClassLoaderClass _CL_Q34java4lang11ClassLoader
extern java::lang::Class ClassLoaderClass;

/////////// java.lang.ClassLoader native methods ////////////

java::lang::ClassLoader *
java::lang::ClassLoader::getSystemClassLoader (void)
{
  JvSynchronize sync (&ClassLoaderClass);
  if (! system)
    system = gnu::gcj::runtime::VMClassLoader::getVMClassLoader ();
  return system;
}

void
java::lang::ClassLoader::defineClass2 (jclass klass, jbyteArray data,
				       jint offset, jint length)
{
#ifdef INTERPRETER
  _Jv_DefineClass (klass, data, offset, length);
#endif
}

java::lang::Class *
java::lang::ClassLoader::defineClass0 (jstring name,
				       jbyteArray data, 
				       jint offset,
				       jint length)
{
#ifdef INTERPRETER
  jclass klass;
  klass = (jclass) JvAllocObject (&ClassClass, sizeof (_Jv_InterpClass));

  // synchronize on the class, so that it is not
  // attempted initialized until we're done loading.
  _Jv_MonitorEnter (klass);

  // record which is the defining loader
  klass->loader = this;

  // register that we are the initiating loader...
  if (name != 0)
    {
      _Jv_Utf8Const *   name2 = _Jv_makeUtf8Const (name);

      _Jv_VerifyClassName (name2);

      klass->name = name2;
    }

  // this will do the magic.  loadInto also operates
  // as an exception trampoline for now...
  Throwable *ex = defineClass1 (klass, data, offset, length);
    
  if (ex)  // we failed to load it
    {
      klass->state = JV_STATE_ERROR;
      klass->notifyAll ();

      _Jv_UnregisterClass (klass);

      _Jv_MonitorExit (klass);
	  
      // FIXME: Here we may want to test that EX does
      // indeed represent a valid exception.  That is,
      // anything but ClassNotFoundException, 
      // or some kind of Error.
	  
      JvThrow (ex);
    }
    
  // if everything proceeded sucessfully, we're loaded.
  JvAssert (klass->state == JV_STATE_LOADED);

  // if an exception is generated, this is initially missed.
  // however, we come back here in handleException0 below...
  _Jv_MonitorExit (klass);

  return klass;

#else // INTERPRETER

  return 0;
#endif
}

void
_Jv_WaitForState (jclass klass, int state)
{
  if (klass->state >= state)
    return;
  
  _Jv_MonitorEnter (klass) ;

  if (state == JV_STATE_LINKED)
    {
      // Must call _Jv_PrepareCompiledClass while holding the class
      // mutex.
      _Jv_PrepareCompiledClass (klass);
      _Jv_MonitorExit (klass);
      return;
    }
	
  java::lang::Thread *self = java::lang::Thread::currentThread();

  // this is similar to the strategy for class initialization.
  // if we already hold the lock, just leave.
  while (klass->state <= state
	 && klass->thread 
	 && klass->thread != self)
    klass->wait ();

  _Jv_MonitorExit (klass);

  if (klass->state == JV_STATE_ERROR)
    {
      _Jv_Throw (new java::lang::LinkageError ());
    }
}

// Finish linking a class.  Only called from ClassLoader::resolveClass.
void
java::lang::ClassLoader::linkClass0 (java::lang::Class *klass)
{
  if (klass->state >= JV_STATE_LINKED)
    return;

#ifdef INTERPRETER
  if (_Jv_IsInterpretedClass (klass))
    {
      _Jv_PrepareClass (klass);
    }
#endif

  _Jv_PrepareCompiledClass (klass);
}

void
java::lang::ClassLoader::markClassErrorState0 (java::lang::Class *klass)
{
  klass->state = JV_STATE_ERROR;
  klass->notifyAll ();
}


/** this is the only native method in VMClassLoader, so 
    we define it here. */
jclass
gnu::gcj::runtime::VMClassLoader::findSystemClass (jstring name)
{
  return _Jv_FindClassInCache (_Jv_makeUtf8Const (name), 0);
}

jclass
java::lang::ClassLoader::findLoadedClass (jstring name)
{
  return _Jv_FindClassInCache (_Jv_makeUtf8Const (name), this);
}


/** This function does class-preparation for compiled classes.  
    NOTE: It contains replicated functionality from
    _Jv_ResolvePoolEntry, and this is intentional, since that function
    lives in resolve.cc which is entirely conditionally compiled.
 */
void
_Jv_PrepareCompiledClass(jclass klass)
{
  if (klass->state >= JV_STATE_LINKED)
    return;

  // Short-circuit, so that mutually dependent classes are ok.
  klass->state = JV_STATE_LINKED;

  _Jv_Constants *pool = &klass->constants;
  for (int index = 1; index < pool->size; ++index)
    {
      if (pool->tags[index] == JV_CONSTANT_Class)
	{
	  _Jv_Utf8Const *name = pool->data[index].utf8;
	  
	  jclass found;
	  if (name->data[0] == '[')
	    found = _Jv_FindClassFromSignature (&name->data[0],
						klass->loader);
	  else
	    found = _Jv_FindClass (name, klass->loader);
		
	  if (! found)
	    {
	      jstring str = _Jv_NewStringUTF (name->data);
	      JvThrow (new java::lang::ClassNotFoundException (str));
	    }

	  pool->data[index].clazz = found;
	  pool->tags[index] |= JV_CONSTANT_ResolvedFlag;
	}
	    
      else if (pool->tags[index] == JV_CONSTANT_String)
	{
	  jstring str;
	  str = _Jv_NewStringUtf8Const (pool->data[index].utf8);
	  pool->data[index].o = str;
	  pool->tags[index] |= JV_CONSTANT_ResolvedFlag;
	}
    }

  klass->notifyAll ();
}


//
//  A single class can have many "initiating" class loaders,
//  and a single "defining" class loader.  The Defining
//  class loader is what is returned from Class.getClassLoader()
//  and is used when loading dependent classes during resolution.
//  The set of initiating class loaders are used to ensure
//  safety of linking, and is maintained in the hash table
//  "initiated_classes".  A defining classloader is by definition also
//  initiating, so we only store classes in this table, if they have more
//  than one class loader associated.
//


// Size of local hash table.
#define HASH_LEN 1013

// Hash function for Utf8Consts.
#define HASH_UTF(Utf) (((Utf)->hash) % HASH_LEN)

struct _Jv_LoaderInfo {
    _Jv_LoaderInfo          *next;
    java::lang::Class       *klass;
    java::lang::ClassLoader *loader;
};

_Jv_LoaderInfo *initiated_classes[HASH_LEN];
jclass loaded_classes[HASH_LEN];

jclass
_Jv_FindClassInCache (_Jv_Utf8Const *name, java::lang::ClassLoader *loader)
{
  _Jv_MonitorEnter (&ClassClass);
  jint hash = HASH_UTF (name);

  // first, if LOADER is a defining loader, then it is also initiating
  jclass klass;
  for (klass = loaded_classes[hash]; klass; klass = klass->next)
    {
      if (loader == klass->loader && _Jv_equalUtf8Consts (name, klass->name))
	break;
    }

  // otherwise, it may be that the class in question was defined
  // by some other loader, but that the loading was initiated by 
  // the loader in question.
  if (!klass)
    {
      _Jv_LoaderInfo *info;
      for (info = initiated_classes[hash]; info; info = info->next)
	{
	  if (loader == info->loader
	      && _Jv_equalUtf8Consts (name, info->klass->name))
	    {
	      klass = info->klass;
	      break;
	    }
	}
    }

  _Jv_MonitorExit (&ClassClass);

  return klass;
}

void
_Jv_UnregisterClass (jclass the_class)
{
  _Jv_MonitorEnter (&ClassClass);
  jint hash = HASH_UTF(the_class->name);

  jclass *klass = &(loaded_classes[hash]);
  for ( ; *klass; klass = &((*klass)->next))
    {
      if (*klass == the_class)
	{
	  *klass = (*klass)->next;
	  break;
	}
    }

  _Jv_LoaderInfo **info = &(initiated_classes[hash]);
  for ( ; *info; info = &((*info)->next))
    {
      while ((*info)->klass == the_class)
	{
	  *info = (*info)->next;
	}
    }

  _Jv_MonitorExit (&ClassClass);
}

void
_Jv_RegisterInitiatingLoader (jclass klass, java::lang::ClassLoader *loader)
{
  _Jv_LoaderInfo *info = new _Jv_LoaderInfo; // non-gc alloc!
  jint hash = HASH_UTF(klass->name);

  _Jv_MonitorEnter (&ClassClass);
  info->loader = loader;
  info->klass  = klass;
  info->next   = initiated_classes[hash];
  initiated_classes[hash] = info;
  _Jv_MonitorExit (&ClassClass);
  
}

// This function is called many times during startup, before main() is
// run.  We do our runtime initialization here the very first time we
// are called.  At that point in time we know for certain we are
// running single-threaded, so we don't need to lock when modifying
// `init'.  CLASSES is NULL-terminated.
void
_Jv_RegisterClasses (jclass *classes)
{
  static bool init = false;

  if (! init)
    {
      init = true;
      _Jv_InitThreads ();
      _Jv_InitGC ();
      _Jv_InitializeSyncMutex ();
    }

  JvSynchronize sync (&ClassClass);
  for (; *classes; ++classes)
    {
      jclass klass = *classes;
      jint hash = HASH_UTF (klass->name);
      klass->next = loaded_classes[hash];
      loaded_classes[hash] = klass;

      // registering a compiled class causes
      // it to be immediately "prepared".  
      if (klass->state == JV_STATE_NOTHING)
	klass->state = JV_STATE_COMPILED;
    }
}

void
_Jv_RegisterClass (jclass klass)
{
  jclass classes[2];
  classes[0] = klass;
  classes[1] = NULL;
  _Jv_RegisterClasses (classes);
}

#if 0
// NOTE: this one is out of date with the new loader stuff...
jclass
_Jv_FindClassInCache (jstring name, java::lang::ClassLoader *loader)
{
  JvSynchronize sync (&ClassClass);
  jint hash = name->hashCode();
  jclass klass = loaded_classes[(_Jv_ushort) hash % HASH_LEN];
  for ( ; klass; klass = klass->next)
    {
      if (loader == klass->loader
	  && _Jv_equal (klass->name, name, hash))
	break;
    }
  _Jv_MonitorExit (&ClassClass);
  return klass;
}
#endif

jclass _Jv_FindClass (_Jv_Utf8Const *name,
		      java::lang::ClassLoader *loader)
{
  jclass klass = _Jv_FindClassInCache (name, loader);

#ifdef INTERPRETER
  if (! klass)
    {
      jstring sname = _Jv_NewStringUTF (name->data);

      if (loader)
	{
	  // Load using a user-defined loader, jvmspec 5.3.2
	  klass = loader->loadClass(sname, false);

	  // If "loader" delegated the loadClass operation to another
	  // loader, explicitly register that it is also an initiating
	  // loader of the given class.
	  if (klass && (klass->getClassLoader () != loader))
	    _Jv_RegisterInitiatingLoader (klass, loader);
	}
      else 
	{
	  java::lang::ClassLoader *sys = java::lang::ClassLoader::system;
	  if (sys == NULL)
	    {
	      _Jv_InitClass (&ClassLoaderClass);
	      sys = java::lang::ClassLoader::getSystemClassLoader ();
	    }

	  // Load using the bootstrap loader jvmspec 5.3.1.
	  klass = sys->loadClass (sname, false); 

	  // Register that we're an initiating loader.
	  if (klass)
	    _Jv_RegisterInitiatingLoader (klass, 0);
	}
    }
  else
    {
      // we need classes to be in the hash while
      // we're loading, so that they can refer to themselves. 
      _Jv_WaitForState (klass, JV_STATE_LOADED);
    }
#endif

  return klass;
}

#if 0
// NOTE: this one is out of date with the new class loader stuff...
jclass
_Jv_FindClass (jstring name, java::lang::ClassLoader *loader)
{
  jclass klass = _Jv_FindClassInCache (name, loader);
  if (! klass)
    {
      if (loader)
	{
	  klass = loader->loadClass(name);
	}
      else
	{
	  // jmspec 5.3.1.2
	  
	  // delegate to the system loader
	  klass = java::lang::ClassLoader::system.loadClass (sname);
	  
	  // register that we're an initiating loader
	  if (klass)
	    _Jv_RegisterInitiatingLoader (klass, 0);
	}
    }
  else
    {
      _Jv_WaitForState (klass, JV_STATE_LOADED);
    }
  
  return klass;
}
#endif

jclass
_Jv_NewClass (_Jv_Utf8Const *name, jclass superclass,
	      java::lang::ClassLoader *loader)
{
  jclass ret = (jclass) JvAllocObject (&ClassClass);

  ret->next = NULL;
  ret->name = name;
  ret->accflags = 0;
  ret->superclass = superclass;
  ret->constants.size = 0;
  ret->constants.tags = NULL;
  ret->constants.data = NULL;
  ret->methods = NULL;
  ret->method_count = 0;
  ret->vtable_method_count = 0;
  ret->fields = NULL;
  ret->size_in_bytes = 0;
  ret->field_count = 0;
  ret->static_field_count = 0;
  ret->vtable = NULL;
  ret->interfaces = NULL;
  ret->loader = loader;
  ret->interface_count = 0;
  ret->state = JV_STATE_NOTHING;
  ret->thread = NULL;

  _Jv_RegisterClass (ret);

  return ret;
}

jclass
_Jv_FindArrayClass (jclass element, java::lang::ClassLoader *loader)
{
  _Jv_Utf8Const *array_name;
  int len;
  if (element->isPrimitive())
    {
      // For primitive types the array is cached in the class.
      jclass ret = (jclass) element->methods;
      if (ret)
	return ret;
      len = 3;
    }
  else
    len = element->name->length + 5;

  {
    char signature[len];
    int index = 0;
    signature[index++] = '[';
    // Compute name of array class to see if we've already cached it.
    if (element->isPrimitive())
      {
	signature[index++] = (char) element->method_count;
      }
    else
      {
	size_t length = element->name->length;
	const char *const name = element->name->data;
	if (name[0] != '[')
	  signature[index++] = 'L';
	memcpy (&signature[index], name, length);
	index += length;
	if (name[0] != '[')
	  signature[index++] = ';';
      }      
    array_name = _Jv_makeUtf8Const (signature, index);
  }

  jclass array_class = _Jv_FindClassInCache (array_name, element->loader);

  if (! array_class)
    {
      // Create new array class.
      array_class = _Jv_NewClass (array_name, &ObjectClass, element->loader);

      // Note that `vtable_method_count' doesn't include the initial
      // NULL slot.
      int dm_count = ObjectClass.vtable_method_count + 1;

      // Create a new vtable by copying Object's vtable (except the
      // class pointer, of course).  Note that we allocate this as
      // unscanned memory -- the vtables are handled specially by the
      // GC.
      int size = (sizeof (_Jv_VTable) +
		  ((dm_count - 1) * sizeof (void *)));
      _Jv_VTable *vtable = (_Jv_VTable *) _Jv_AllocBytes (size);
      vtable->clas = array_class;
      memcpy (vtable->method, ObjectClass.vtable->method,
	      dm_count * sizeof (void *));
      array_class->vtable = vtable;
      array_class->vtable_method_count = ObjectClass.vtable_method_count;

      // Stash the pointer to the element type.
      array_class->methods = (_Jv_Method *) element;

      // Register our interfaces.
      // FIXME: for JDK 1.2 we need Serializable.
      static jclass interfaces[] = { &CloneableClass };
      array_class->interfaces = interfaces;
      array_class->interface_count = 1;

      // as per vmspec 5.3.3.2
      array_class->accflags = element->accflags;

      // FIXME: initialize other Class instance variables,
      // e.g. `fields'.

      // say this class is initialized and ready to go!
      array_class->state = JV_STATE_DONE;

      // vmspec, section 5.3.3 describes this
      if (element->loader != loader)
	_Jv_RegisterInitiatingLoader (array_class, loader);
    }

  // For primitive types, point back at this array.
  if (element->isPrimitive())
    element->methods = (_Jv_Method *) array_class;

  return array_class;
}