source: trunk/src/gcc/libjava/defineclass.cc@ 94

// defineclass.cc - defining a class from .class format.

/* Copyright (C) 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.  */

/* 
   Author: Kresten Krab Thorup <[email protected]> 

   Written using the online versions of Java Language Specification (1st
   ed.) and The Java Virtual Machine Specification (2nd ed.). 

   Future work may include reading (and handling) attributes which are
   currently being ignored ("InnerClasses", "LineNumber", etc...).  
*/

#include <config.h>

#include <java-interp.h>

#include <stdlib.h>
#include <java-cpool.h>
#include <gcj/cni.h>

#include <java/lang/Class.h>
#include <java/lang/Float.h>
#include <java/lang/Double.h>
#include <java/lang/Character.h>
#include <java/lang/LinkageError.h>
#include <java/lang/InternalError.h>
#include <java/lang/ClassFormatError.h>
#include <java/lang/NoClassDefFoundError.h>
#include <java/lang/ClassCircularityError.h>
#include <java/lang/ClassNotFoundException.h>
#include <java/lang/IncompatibleClassChangeError.h>
#include <java/lang/reflect/Modifier.h>

using namespace gcj;

#ifdef INTERPRETER

// these go in some separate functions, to avoid having _Jv_InitClass
// inserted all over the place.
static void throw_internal_error (char *msg)
        __attribute__ ((__noreturn__));
static void throw_no_class_def_found_error (jstring msg)
        __attribute__ ((__noreturn__));
static void throw_no_class_def_found_error (char *msg)
        __attribute__ ((__noreturn__));
static void throw_class_format_error (jstring msg)
        __attribute__ ((__noreturn__));
static void throw_incompatible_class_change_error (jstring msg)
        __attribute__ ((__noreturn__));
static void throw_class_circularity_error (jstring msg)
        __attribute__ ((__noreturn__));

/**
 * We define class reading using a class.  It is practical, since then
 * the entire class-reader can be a friend of class Class (it needs to
 * write all it's different structures); but also because this makes it
 * easy to make class definition reentrant, and thus two threads can be
 * defining classes at the same time.   This class (_Jv_ClassReader) is
 * never exposed outside this file, so we don't have to worry about
 * public or private members here.
 */

struct _Jv_ClassReader {

  // do verification?  Currently, there is no option to disable this.
  // This flag just controls the verificaiton done by the class loader;
  // i.e., checking the integrity of the constant pool; and it is
  // allways on.  You always want this as far as I can see, but it also
  // controls weither identifiers and type descriptors/signatures are
  // verified as legal.  This could be somewhat more expensive since it
  // will call Characher.isJavaIdentifier{Start,Part} for each character
  // in any identifier (field name or method name) it comes by.  Thus,
  // it might be useful to turn off this verification for classes that
  // come from a trusted source.  However, for GCJ, trusted classes are
  // most likely to be linked in.

  bool verify;

  // input data.
  unsigned char     *bytes;
  int                len;

  // current input position
  int                pos;

  // the constant pool data
  int pool_count;
  unsigned char     *tags;
  unsigned int      *offsets;

  // the class to define (see java-interp.h)
  _Jv_InterpClass   *def;

  /* check that the given number of input bytes are available */
  inline void check (int num)
  {
    if (pos + num > len)
      throw_class_format_error ("Premature end of data");
  }

  /* skip a given number of bytes in input */
  inline void skip (int num)
  {
    check (num);
    pos += num;
  }
  
  /* read an unsignend 1-byte unit */
  inline static jint get1u (unsigned char* bytes)
  {
    return bytes[0];
  }
  
  /* read an unsigned 1-byte unit */
  inline jint read1u ()
  {
    skip (1);
    return get1u (bytes+pos-1);
  }
  
  /* read an unsigned 2-byte unit */