gcc/libjava/prims.cc

// prims.cc - Code for core of runtime environment.

/* Copyright (C) 1998, 1999, 2000, 2001  Free Software Foundation

   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.  */

#include <config.h>

#ifdef USE_WIN32_SIGNALLING
#include <windows.h>
#endif /* USE_WIN32_SIGNALLING */

#ifdef USE_WINSOCK
#undef __INSIDE_CYGWIN__
#include <winsock.h>
#endif /* USE_WINSOCK */

#include <stdlib.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include <gcj/cni.h>
#include <jvm.h>
#include <java-signal.h>
#include <java-threads.h>

#ifdef ENABLE_JVMPI
#include <jvmpi.h>
#include <java/lang/ThreadGroup.h>
#endif

#ifndef DISABLE_GETENV_PROPERTIES
#include <ctype.h>
#include <java-props.h>
#define PROCESS_GCJ_PROPERTIES process_gcj_properties()
#else
#define PROCESS_GCJ_PROPERTIES
#endif // DISABLE_GETENV_PROPERTIES

#include <java/lang/Class.h>
#include <java/lang/ClassLoader.h>
#include <java/lang/Runtime.h>
#include <java/lang/String.h>
#include <java/lang/Thread.h>
#include <java/lang/ThreadGroup.h>
#include <gnu/gcj/runtime/FirstThread.h>
#include <java/lang/ArrayIndexOutOfBoundsException.h>
#include <java/lang/ArithmeticException.h>
#include <java/lang/ClassFormatError.h>
#include <java/lang/NegativeArraySizeException.h>
#include <java/lang/NullPointerException.h>
#include <java/lang/OutOfMemoryError.h>
#include <java/lang/System.h>
#include <java/lang/reflect/Modifier.h>
#include <java/io/PrintStream.h>
#include <java/lang/UnsatisfiedLinkError.h>

#ifdef USE_LTDL
#include <ltdl.h>
#endif

// We allocate a single OutOfMemoryError exception which we keep
// around for use if we run out of memory.
static java::lang::OutOfMemoryError *no_memory;

// Largest representable size_t.
#define SIZE_T_MAX ((size_t) (~ (size_t) 0))

static const char *no_properties[] = { NULL };

// Properties set at compile time.
const char **_Jv_Compiler_Properties = no_properties;

// The JAR file to add to the beginning of java.class.path.
const char *_Jv_Jar_Class_Path;

#ifndef DISABLE_GETENV_PROPERTIES
// Property key/value pairs.
property_pair *_Jv_Environment_Properties;
#endif

// The name of this executable.
static char * _Jv_execName;

// Stash the argv pointer to benefit native libraries that need it.
const char **_Jv_argv;
int _Jv_argc;

typedef void main_func (jobject);

#ifdef ENABLE_JVMPI
// Pointer to JVMPI notification functions.
void (*_Jv_JVMPI_Notify_OBJECT_ALLOC) (JVMPI_Event *event);
void (*_Jv_JVMPI_Notify_THREAD_START) (JVMPI_Event *event);
void (*_Jv_JVMPI_Notify_THREAD_END) (JVMPI_Event *event);
#endif


extern "C" void _Jv_ThrowSignal (jthrowable) __attribute ((noreturn));

// Just like _Jv_Throw, but fill in the stack trace first.  Although
// this is declared extern in order that its name not be mangled, it
// is not intended to be used outside this file.
void 
_Jv_ThrowSignal (jthrowable throwable)
{
  throwable->fillInStackTrace ();
  throw throwable;
}
 
#ifdef HANDLE_SEGV
static java::lang::NullPointerException *nullp;

SIGNAL_HANDLER (catch_segv)
{
  MAKE_THROW_FRAME (nullp);
  _Jv_ThrowSignal (nullp);
}
#endif

static java::lang::ArithmeticException *arithexception;

#ifdef HANDLE_FPE
SIGNAL_HANDLER (catch_fpe)
{
#ifdef HANDLE_DIVIDE_OVERFLOW
  HANDLE_DIVIDE_OVERFLOW;
#else
  MAKE_THROW_FRAME (arithexception);
#endif
  _Jv_ThrowSignal (arithexception);
}
#endif



jboolean
_Jv_equalUtf8Consts (Utf8Const* a, Utf8Const *b)
{
  int len;
  _Jv_ushort *aptr, *bptr;
  if (a == b)
    return true;
  if (a->hash != b->hash)
    return false;
  len = a->length;
  if (b->length != len)
    return false;
  aptr = (_Jv_ushort *)a->data;
  bptr = (_Jv_ushort *)b->data;
  len = (len + 1) >> 1;
  while (--len >= 0)
    if (*aptr++ != *bptr++)
      return false;
  return true;
}

/* True iff A is equal to STR.
   HASH is STR->hashCode().  
*/

jboolean
_Jv_equal (Utf8Const* a, jstring str, jint hash)
{
  if (a->hash != (_Jv_ushort) hash)
    return false;
  jint len = str->length();
  jint i = 0;
  jchar *sptr = _Jv_GetStringChars (str);
  unsigned char* ptr = (unsigned char*) a->data;
  unsigned char* limit = ptr + a->length;
  for (;; i++, sptr++)
    {
      int ch = UTF8_GET (ptr, limit);
      if (i == len)
	return ch < 0;
      if (ch != *sptr)
	return false;
    }
  return true;
}

/* Like _Jv_equal, but stop after N characters.  */
jboolean
_Jv_equaln (Utf8Const *a, jstring str, jint n)
{
  jint len = str->length();
  jint i = 0;
  jchar *sptr = _Jv_GetStringChars (str);
  unsigned char* ptr = (unsigned char*) a->data;
  unsigned char* limit = ptr + a->length;
  for (; n-- > 0; i++, sptr++)
    {
      int ch = UTF8_GET (ptr, limit);
      if (i == len)
	return ch < 0;
      if (ch != *sptr)
	return false;
    }
  return true;
}

/* Count the number of Unicode chars encoded in a given Ut8 string. */
int
_Jv_strLengthUtf8(char* str, int len)
{
  unsigned char* ptr;
  unsigned char* limit;
  int str_length;

  ptr = (unsigned char*) str;
  limit = ptr + len;
  str_length = 0;
  for (; ptr < limit; str_length++) {
    if (UTF8_GET (ptr, limit) < 0) {
      return (-1);
    }
  }
  return (str_length);
}

/* Calculate a hash value for a string encoded in Utf8 format.
 * This returns the same hash value as specified or java.lang.String.hashCode.
 */
static jint
hashUtf8String (char* str, int len)
{
  unsigned char* ptr = (unsigned char*) str;
  unsigned char* limit = ptr + len;
  jint hash = 0;

  for (; ptr < limit;)
    {
      int ch = UTF8_GET (ptr, limit);
      /* Updated specification from
	 http://www.javasoft.com/docs/books/jls/clarify.html. */
      hash = (31 * hash) + ch;
    }
  return hash;
}

_Jv_Utf8Const *
_Jv_makeUtf8Const (char* s, int len)
{
  if (len < 0)
    len = strlen (s);
  Utf8Const* m = (Utf8Const*) _Jv_AllocBytes (sizeof(Utf8Const) + len + 1);
  if (! m)
    throw no_memory;
  memcpy (m->data, s, len);
  m->data[len] = 0;
  m->length = len;
  m->hash = hashUtf8String (s, len) & 0xFFFF;
  return (m);
}

_Jv_Utf8Const *
_Jv_makeUtf8Const (jstring string)
{
  jint hash = string->hashCode ();
  jint len = _Jv_GetStringUTFLength (string);

  Utf8Const* m = (Utf8Const*)
    _Jv_AllocBytesChecked (sizeof(Utf8Const) + len + 1);

  m->hash = hash;
  m->length = len;

  _Jv_GetStringUTFRegion (string, 0, string->length (), m->data);
  m->data[len] = 0;
  
  return m;
}



#ifdef DEBUG
void
_Jv_Abort (const char *function, const char *file, int line,
	   const char *message)
#else
void
_Jv_Abort (const char *, const char *, int, const char *message)
#endif
{
#ifdef DEBUG
  fprintf (stderr,
	   "libgcj failure: %s\n   in function %s, file %s, line %d\n",
	   message, function, file, line);
#else
  java::io::PrintStream *err = java::lang::System::err;
  err->print(JvNewStringLatin1 ("libgcj failure: "));
  err->println(JvNewStringLatin1 (message));
  err->flush();
#endif
  abort ();
}

static void
fail_on_finalization (jobject)
{
  JvFail ("object was finalized");
}

void
_Jv_GCWatch (jobject obj)
{
  _Jv_RegisterFinalizer (obj, fail_on_finalization);
}

void
_Jv_ThrowBadArrayIndex(jint bad_index)
{
  throw new java::lang::ArrayIndexOutOfBoundsException
    (java::lang::String::valueOf (bad_index));
}

void
_Jv_ThrowNullPointerException ()
{
  throw new java::lang::NullPointerException;
}

// Allocate some unscanned memory and throw an exception if no memory.
void *
_Jv_AllocBytesChecked (jsize size)
{
  void *r = _Jv_AllocBytes (size);
  if (! r)
    throw no_memory;
  return r;
}

// Allocate a new object of class KLASS.  SIZE is the size of the object
// to allocate.  You might think this is redundant, but it isn't; some
// classes, such as String, aren't of fixed size.
jobject
_Jv_AllocObject (jclass klass, jint size)
{
  _Jv_InitClass (klass);

  jobject obj = (jobject) _Jv_AllocObj (size, klass);
  if (__builtin_expect (! obj, false))
    throw no_memory;

  // If this class has inherited finalize from Object, then don't
  // bother registering a finalizer.  We know that finalize() is the
  // very first method after the dummy entry.  If this turns out to be
  // unreliable, a more robust implementation can be written.  Such an
  // implementation would look for Object.finalize in Object's method
  // table at startup, and then use that information to find the
  // appropriate index in the method vector.
  if (klass->vtable->get_finalizer()
      != java::lang::Object::class$.vtable->get_finalizer())
    _Jv_RegisterFinalizer (obj, _Jv_FinalizeObject);

#ifdef ENABLE_JVMPI
  // Service JVMPI request.

  if (__builtin_expect (_Jv_JVMPI_Notify_OBJECT_ALLOC != 0, false))
    {
      JVMPI_Event event;

      event.event_type = JVMPI_EVENT_OBJECT_ALLOC;
      event.env_id = NULL;
      event.u.obj_alloc.arena_id = 0;
      event.u.obj_alloc.class_id = (jobjectID) klass;
      event.u.obj_alloc.is_array = 0;
      event.u.obj_alloc.size = size;
      event.u.obj_alloc.obj_id = (jobjectID) obj;

      _Jv_DisableGC ();
      (*_Jv_JVMPI_Notify_OBJECT_ALLOC) (&event);
      _Jv_EnableGC ();
    }
#endif

  return obj;
}

// Allocate a new array of Java objects.  Each object is of type
// `elementClass'.  `init' is used to initialize each slot in the
// array.
jobjectArray
_Jv_NewObjectArray (jsize count, jclass elementClass, jobject init)
{
  if (__builtin_expect (count < 0, false))
    throw new java::lang::NegativeArraySizeException;

  JvAssert (! elementClass->isPrimitive ());

  // Ensure that elements pointer is properly aligned.
  jobjectArray obj = NULL;
  size_t size = (size_t) elements (obj);
  size += count * sizeof (jobject);

  // FIXME: second argument should be "current loader"
  jclass klass = _Jv_GetArrayClass (elementClass, 0);

  obj = (jobjectArray) _Jv_AllocArray (size, klass);
  if (__builtin_expect (! obj, false))
    throw no_memory;
  // Cast away const.
  jsize *lp = const_cast<jsize *> (&obj->length);
  *lp = count;
  // We know the allocator returns zeroed memory.  So don't bother
  // zeroing it again.
  if (init)
    {
      jobject *ptr = elements(obj);
      while (--count >= 0)
	*ptr++ = init;
    }
  return obj;
}

// Allocate a new array of primitives.  ELTYPE is the type of the
// element, COUNT is the size of the array.
jobject
_Jv_NewPrimArray (jclass eltype, jint count)
{
  int elsize = eltype->size();
  if (__builtin_expect (count < 0, false))
    throw new java::lang::NegativeArraySizeException;

  JvAssert (eltype->isPrimitive ());
  jobject dummy = NULL;
  size_t size = (size_t) _Jv_GetArrayElementFromElementType (dummy, eltype);

  // Check for overflow.
  if (__builtin_expect ((size_t) count > 
			(SIZE_T_MAX - size) / elsize, false))
    throw no_memory;

  jclass klass = _Jv_GetArrayClass (eltype, 0);

  __JArray *arr = (__JArray*) _Jv_AllocObj (size + elsize * count, klass);
  if (__builtin_expect (! arr, false))
    throw no_memory;
  // Cast away const.
  jsize *lp = const_cast<jsize *> (&arr->length);
  *lp = count;
  // Note that we assume we are given zeroed memory by the allocator.

  return arr;
}

jobject
_Jv_NewArray (jint type, jint size)
{
  switch (type)
    {
      case  4:  return JvNewBooleanArray (size);
      case  5:  return JvNewCharArray (size);
      case  6:  return JvNewFloatArray (size);
      case  7:  return JvNewDoubleArray (size);
      case  8:  return JvNewByteArray (size);
      case  9:  return JvNewShortArray (size);
      case 10:  return JvNewIntArray (size);
      case 11:  return JvNewLongArray (size);
    }
  JvFail ("newarray - bad type code");
  return NULL;			// Placate compiler.
}

jobject
_Jv_NewMultiArray (jclass type, jint dimensions, jint *sizes)
{
  JvAssert (type->isArray());
  jclass element_type = type->getComponentType();
  jobject result;
  if (element_type->isPrimitive())
    result = _Jv_NewPrimArray (element_type, sizes[0]);
  else
    result = _Jv_NewObjectArray (sizes[0], element_type, NULL);

  if (dimensions > 1)
    {
      JvAssert (! element_type->isPrimitive());
      JvAssert (element_type->isArray());
      jobject *contents = elements ((jobjectArray) result);
      for (int i = 0; i < sizes[0]; ++i)
	contents[i] = _Jv_NewMultiArray (element_type, dimensions - 1,
					 sizes + 1);
    }

  return result;
}

jobject
_Jv_NewMultiArray (jclass array_type, jint dimensions, ...)
{
  va_list args;
  jint sizes[dimensions];
  va_start (args, dimensions);
  for (int i = 0; i < dimensions; ++i)
    {
      jint size = va_arg (args, jint);
      sizes[i] = size;
    }
  va_end (args);

  return _Jv_NewMultiArray (array_type, dimensions, sizes);
}



#define DECLARE_PRIM_TYPE(NAME, SIG, LEN)				\
  _Jv_ArrayVTable _Jv_##NAME##VTable;					\
  java::lang::Class _Jv_##NAME##Class ((jobject) #NAME,			\
				       (jbyte) SIG, (jint) LEN,		\
				       (jobject) &_Jv_##NAME##VTable);

DECLARE_PRIM_TYPE(byte, 'B', 1);
DECLARE_PRIM_TYPE(short, 'S', 2);
DECLARE_PRIM_TYPE(int, 'I', 4);
DECLARE_PRIM_TYPE(long, 'J', 8);
DECLARE_PRIM_TYPE(boolean, 'Z', 1);
DECLARE_PRIM_TYPE(char, 'C', 2);
DECLARE_PRIM_TYPE(float, 'F', 4);
DECLARE_PRIM_TYPE(double, 'D', 8);
DECLARE_PRIM_TYPE(void, 'V', 0);

jclass
_Jv_FindClassFromSignature (char *sig, java::lang::ClassLoader *loader)
{
  switch (*sig)
    {
    case 'B':
      return JvPrimClass (byte);
    case 'S':
      return JvPrimClass (short);
    case 'I':
      return JvPrimClass (int);
    case 'J':
      return JvPrimClass (long);
    case 'Z':
      return JvPrimClass (boolean);
    case 'C':
      return JvPrimClass (char);
    case 'F':
      return JvPrimClass (float);
    case 'D':
      return JvPrimClass (double);
    case 'V':
      return JvPrimClass (void);
    case 'L':
      {
	int i;
	for (i = 1; sig[i] && sig[i] != ';'; ++i)
	  ;
	_Jv_Utf8Const *name = _Jv_makeUtf8Const (&sig[1], i - 1);
	return _Jv_FindClass (name, loader);

      }
    case '[':
      {
	jclass klass = _Jv_FindClassFromSignature (&sig[1], loader);
	if (! klass)
	  return NULL;
	return _Jv_GetArrayClass (klass, loader);
      }
    }

  return NULL;			// Placate compiler.
}



JArray<jstring> *
JvConvertArgv (int argc, const char **argv)
{
  if (argc < 0)
    argc = 0;
  jobjectArray ar = JvNewObjectArray(argc, &StringClass, NULL);
  jobject* ptr = elements(ar);
  for (int i = 0;  i < argc;  i++)
    {
      const char *arg = argv[i];
      // FIXME - should probably use JvNewStringUTF.
      *ptr++ = JvNewStringLatin1(arg, strlen(arg));
    }
  return (JArray<jstring>*) ar;
}

// FIXME: These variables are static so that they will be
// automatically scanned by the Boehm collector.  This is needed
// because with qthreads the collector won't scan the initial stack --
// it will only scan the qthreads stacks.

// Command line arguments.
static jobject arg_vec;

// The primary thread.
static java::lang::Thread *main_thread;

char *
_Jv_ThisExecutable (void)
{
  return _Jv_execName;
}

void
_Jv_ThisExecutable (const char *name)
{
  if (name)
    {
      _Jv_execName = (char *) _Jv_Malloc (strlen (name) + 1);
      strcpy (_Jv_execName, name);
    }
}

#ifdef USE_WIN32_SIGNALLING

extern "C" int* win32_get_restart_frame (void *);

LONG CALLBACK
win32_exception_handler (LPEXCEPTION_POINTERS e)
{
  int* setjmp_buf;
  if (e->ExceptionRecord->ExceptionCode == EXCEPTION_ACCESS_VIOLATION)   
    setjmp_buf = win32_get_restart_frame (nullp);
  else if (e->ExceptionRecord->ExceptionCode == EXCEPTION_INT_DIVIDE_BY_ZERO)
    setjmp_buf = win32_get_restart_frame (arithexception);
  else
    return EXCEPTION_CONTINUE_SEARCH;

  e->ContextRecord->Ebp = setjmp_buf[0];
  // FIXME: Why does i386-signal.h increment the PC here, do we need to do it?
  e->ContextRecord->Eip = setjmp_buf[1];
  // FIXME: Is this the stack pointer? Do we need it?
  e->ContextRecord->Esp = setjmp_buf[2];

  return EXCEPTION_CONTINUE_EXECUTION;
}

#endif

/* This will be non-NULL if the user has preloaded a JNI library, or
   linked one into the executable.  */
extern "C" 
{
#pragma weak JNI_OnLoad
  extern jint JNI_OnLoad (JavaVM *, void *) __attribute__((weak));
}


#ifndef DISABLE_GETENV_PROPERTIES

static char *
next_property_key (char *s, size_t *length)
{
  size_t l = 0;

  JvAssert (s);

  // Skip over whitespace
  while (isspace (*s))
    s++;

  // If we've reached the end, return NULL.  Also return NULL if for
  // some reason we've come across a malformed property string.
  if (*s == 0
      || *s == ':'
      || *s == '=')
    return NULL;

  // Determine the length of the property key.
  while (s[l] != 0
	 && ! isspace (s[l])
	 && s[l] != ':'
	 && s[l] != '=')
    {
      if (s[l] == '\\'
	  && s[l+1] != 0)
	l++;
      l++;
    }

  *length = l;

  return s;
}

static char *
next_property_value (char *s, size_t *length)
{
  size_t l = 0;

  JvAssert (s);

  while (isspace (*s))
    s++;

  if (*s == ':'
      || *s == '=')
    s++;

  while (isspace (*s))
    s++;

  // If we've reached the end, return NULL.
  if (*s == 0)
    return NULL;

  // Determine the length of the property value.
  while (s[l] != 0
	 && ! isspace (s[l])
	 && s[l] != ':'
	 && s[l] != '=')
    {
      if (s[l] == '\\'
	  && s[l+1] != 0)
	l += 2;
      else
	l++;
    }

  *length = l;

  return s;
}

static void
process_gcj_properties ()
{
  char *props = getenv("GCJ_PROPERTIES");
  char *p = props;
  size_t length;
  size_t property_count = 0;

  if (NULL == props)
    return;

  // Whip through props quickly in order to count the number of
  // property values.
  while (p && (p = next_property_key (p, &length)))
    {
      // Skip to the end of the key
      p += length;

      p = next_property_value (p, &length);
      if (p)
	p += length;
      
      property_count++;
    }

  // Allocate an array of property value/key pairs.
  _Jv_Environment_Properties = 
    (property_pair *) malloc (sizeof(property_pair) 
			      * (property_count + 1));

  // Go through the properties again, initializing _Jv_Properties
  // along the way.
  p = props;
  property_count = 0;
  while (p && (p = next_property_key (p, &length)))
    {
      _Jv_Environment_Properties[property_count].key = p;
      _Jv_Environment_Properties[property_count].key_length = length;

      // Skip to the end of the key
      p += length;

      p = next_property_value (p, &length);
      
      _Jv_Environment_Properties[property_count].value = p;
      _Jv_Environment_Properties[property_count].value_length = length;

      if (p)
	p += length;

      property_count++;
    }
  memset ((void *) &_Jv_Environment_Properties[property_count], 
	  0, sizeof (property_pair));
  {
    size_t i = 0;

    // Null terminate the strings.
    while (_Jv_Environment_Properties[i].key)
      {
	_Jv_Environment_Properties[i].key[_Jv_Environment_Properties[i].key_length] = 0;
	_Jv_Environment_Properties[i++].value[_Jv_Environment_Properties[i].value_length] = 0;
      }
  }
}
#endif // DISABLE_GETENV_PROPERTIES

jint
_Jv_CreateJavaVM (void* /*vm_args*/)
{
  PROCESS_GCJ_PROPERTIES;

  // Turn stack trace generation off while creating exception objects.
  _Jv_InitClass (&java::lang::Throwable::class$);
  java::lang::Throwable::trace_enabled = 0;
  
  INIT_SEGV;
#ifdef HANDLE_FPE
  INIT_FPE;
#else
  arithexception = new java::lang::ArithmeticException
    (JvNewStringLatin1 ("/ by zero"));
#endif

  no_memory = new java::lang::OutOfMemoryError;

  java::lang::Throwable::trace_enabled = 1;

#ifdef USE_LTDL
  LTDL_SET_PRELOADED_SYMBOLS ();
#endif

#ifdef USE_WINSOCK
  // Initialise winsock for networking
  WSADATA data;
  if (WSAStartup (MAKEWORD (1, 1), &data))
      MessageBox (NULL, "Error initialising winsock library.", "Error", MB_OK | MB_ICONEXCLAMATION);
#endif /* USE_WINSOCK */

#ifdef USE_WIN32_SIGNALLING
  // Install exception handler
  SetUnhandledExceptionFilter (win32_exception_handler);
#else
  // We only want this on POSIX systems.
  struct sigaction act;
  act.sa_handler = SIG_IGN;
  sigemptyset (&act.sa_mask);
  act.sa_flags = 0;
  sigaction (SIGPIPE, &act, NULL);
#endif /* USE_WIN32_SIGNALLING */

  _Jv_JNI_Init ();

  /* Some systems let you preload shared libraries before running a
     program.  Under Linux, this is done by setting the LD_PRELOAD
     environment variable.  We take advatage of this here to allow for
     dynamically loading a JNI library into a fully linked executable.  */

  if (JNI_OnLoad != NULL)
    {
      JavaVM *vm = _Jv_GetJavaVM ();
      if (vm == NULL)
	{
	  // FIXME: what?
	  return -1;
	}
      jint vers = JNI_OnLoad (vm, NULL);
      if (vers != JNI_VERSION_1_1 && vers != JNI_VERSION_1_2)
	{
	  // FIXME: unload the library.
	  _Jv_Throw (new java::lang::UnsatisfiedLinkError (JvNewStringLatin1 ("unrecognized version from preloaded JNI_OnLoad")));
	}
    }
  return 0;
}

static void
runFirst (::java::lang::Class *klass, ::java::lang::Object *args)
{
  Utf8Const* main_signature = _Jv_makeUtf8Const ("([Ljava.lang.String;)V", 22);
  Utf8Const* main_name = _Jv_makeUtf8Const ("main", 4);

  _Jv_Method *meth = _Jv_GetMethodLocal (klass, main_name, main_signature);

  // Some checks from Java Spec section 12.1.4.
  const char *msg = NULL;
  if (meth == NULL)
    msg = "no suitable method `main' in class";
  else if (! java::lang::reflect::Modifier::isStatic(meth->accflags))
    msg = "`main' must be static";
  else if (! java::lang::reflect::Modifier::isPublic(meth->accflags))
    msg =  "`main' must be public";
  if (msg != NULL)
    {
      fprintf (stderr, "%s\n", msg);
      ::exit(1);
    }

#ifdef WITH_JVMPI
  if (_Jv_JVMPI_Notify_THREAD_START)
    {
      JVMPI_Event event;

      jstring thread_name = getName ();
      jstring group_name = NULL, parent_name = NULL;
      java::lang::ThreadGroup *group = getThreadGroup ();

      if (group)
	{
	  group_name = group->getName ();
	  group = group->getParent ();

	  if (group)
	    parent_name = group->getName ();
	}

      int thread_len = thread_name ? JvGetStringUTFLength (thread_name) : 0;
      int group_len = group_name ? JvGetStringUTFLength (group_name) : 0;
      int parent_len = parent_name ? JvGetStringUTFLength (parent_name) : 0;

      char thread_chars[thread_len + 1];
      char group_chars[group_len + 1];
      char parent_chars[parent_len + 1];

      if (thread_name)
	JvGetStringUTFRegion (thread_name, 0, 
			      thread_name->length(), thread_chars);
      if (group_name)
	JvGetStringUTFRegion (group_name, 0, 
			      group_name->length(), group_chars);
      if (parent_name)
	JvGetStringUTFRegion (parent_name, 0, 
			      parent_name->length(), parent_chars);

      thread_chars[thread_len] = '\0';
      group_chars[group_len] = '\0';
      parent_chars[parent_len] = '\0';

      event.event_type = JVMPI_EVENT_THREAD_START;
      event.env_id = NULL;
      event.u.thread_start.thread_name = thread_chars;
      event.u.thread_start.group_name = group_chars;
      event.u.thread_start.parent_name = parent_chars;
      event.u.thread_start.thread_id = (jobjectID) this;
      event.u.thread_start.thread_env_id = _Jv_GetCurrentJNIEnv ();

      _Jv_DisableGC ();
      (*_Jv_JVMPI_Notify_THREAD_START) (&event);
      _Jv_EnableGC ();
    }
#endif

  main_func *real_main = (main_func *) meth->ncode;
  (*real_main) (args);
}

void
JvRunMain (jclass klass, int argc, const char **argv)
{
  _Jv_argv = argv;
  _Jv_argc = argc;

  _Jv_CreateJavaVM (NULL);
#ifdef HAVE_PROC_SELF_EXE
  char exec_name[20];
  sprintf (exec_name, "/proc/%d/exe", getpid ());
  _Jv_ThisExecutable (exec_name);
#else
  _Jv_ThisExecutable (argv[0]);
#endif

  main_thread = _Jv_AttachCurrentThread (JvNewStringLatin1 ("main"), NULL);
  arg_vec = JvConvertArgv (argc - 1, argv + 1);
  runFirst (klass, arg_vec);
  _Jv_ThreadWait ();

  int status = (int) java::lang::ThreadGroup::had_uncaught_exception;
    
  java::lang::Runtime::getRuntime ()->_exit (status);
}

void
_Jv_RunMain (const char *name, int argc, const char **argv, bool is_jar)
{
  jstring class_name;

  _Jv_CreateJavaVM (NULL);

#ifdef HAVE_PROC_SELF_EXE
  char exec_name[20];
  sprintf (exec_name, "/proc/%d/exe", getpid ());
  _Jv_ThisExecutable (exec_name);
#endif

  main_thread = _Jv_AttachCurrentThread (JvNewStringLatin1 ("main"), NULL);

  if (is_jar)
    {
      // name specifies a jar file.  We must now extract the
      // Main-Class attribute from the jar's manifest file.
      // This is done by gnu.gcj.runtime.FirstThread.getMain.
      _Jv_Jar_Class_Path = strdup (name);
      jstring jar_name = JvNewStringLatin1 (name);
      // FirstThread.getMain extracts the main class name.
      class_name = gnu::gcj::runtime::FirstThread::getMain (jar_name);

      // We need a new ClassLoader because the classpath must be the
      // jar file only.  The easiest way to do this is to lose our
      // reference to the previous classloader.
      java::lang::ClassLoader::system = NULL;
    }
  else
    class_name = JvNewStringLatin1 (name);

  arg_vec = JvConvertArgv (argc - 1, argv + 1);

  if (class_name)
    {
      runFirst(java::lang::Class::forName (class_name), arg_vec);
      _Jv_ThreadWait ();
    }

  int status = (int) java::lang::ThreadGroup::had_uncaught_exception;

  java::lang::Runtime::getRuntime ()->exit (status);
}



// Parse a string and return a heap size.
static size_t
parse_heap_size (const char *spec)
{
  char *end;
  unsigned long val = strtoul (spec, &end, 10);
  if (*end == 'k' || *end == 'K')
    val *= 1024;
  else if (*end == 'm' || *end == 'M')
    val *= 1048576;
  return (size_t) val;
}

// Set the initial heap size.  This might be ignored by the GC layer.
// This must be called before _Jv_RunMain.
void
_Jv_SetInitialHeapSize (const char *arg)
{
  size_t size = parse_heap_size (arg);
  _Jv_GCSetInitialHeapSize (size);
}

// Set the maximum heap size.  This might be ignored by the GC layer.
// This must be called before _Jv_RunMain.
void
_Jv_SetMaximumHeapSize (const char *arg)
{
  size_t size = parse_heap_size (arg);
  _Jv_GCSetMaximumHeapSize (size);
}



void *
_Jv_Malloc (jsize size)
{
  if (__builtin_expect (size == 0, false))
    size = 1;
  void *ptr = malloc ((size_t) size);
  if (__builtin_expect (ptr == NULL, false))
    throw no_memory;
  return ptr;
}

void *
_Jv_Realloc (void *ptr, jsize size)
{
  if (__builtin_expect (size == 0, false))
    size = 1;
  ptr = realloc (ptr, (size_t) size);
  if (__builtin_expect (ptr == NULL, false))
    throw no_memory;
  return ptr;
}

void *
_Jv_MallocUnchecked (jsize size)
{
  if (__builtin_expect (size == 0, false))
    size = 1;
  return malloc ((size_t) size);
}

void
_Jv_Free (void* ptr)
{
  return free (ptr);
}



// In theory, these routines can be #ifdef'd away on machines which
// support divide overflow signals.  However, we never know if some
// code might have been compiled with "-fuse-divide-subroutine", so we
// always include them in libgcj.

jint
_Jv_divI (jint dividend, jint divisor)
{
  if (__builtin_expect (divisor == 0, false))
    _Jv_ThrowSignal (arithexception);
  
  if (dividend == (jint) 0x80000000L && divisor == -1)
    return dividend;

  return dividend / divisor;
}

jint
_Jv_remI (jint dividend, jint divisor)
{
  if (__builtin_expect (divisor == 0, false))
    _Jv_ThrowSignal (arithexception);
  
  if (dividend == (jint) 0x80000000L && divisor == -1)
    return 0;

  return dividend % divisor;
}

jlong
_Jv_divJ (jlong dividend, jlong divisor)
{
  if (__builtin_expect (divisor == 0, false))
    _Jv_ThrowSignal (arithexception);
  
  if (dividend == (jlong) 0x8000000000000000LL && divisor == -1)
    return dividend;

  return dividend / divisor;
}

jlong
_Jv_remJ (jlong dividend, jlong divisor)
{
  if (__builtin_expect (divisor == 0, false))
    _Jv_ThrowSignal (arithexception);
  
  if (dividend == (jlong) 0x8000000000000000LL && divisor == -1)
    return 0;

  return dividend % divisor;
}