/*
* reserved comment block
* DO NOT REMOVE OR ALTER!
*/
package com.sun.org.apache.bcel.internal.classfile;
/* ====================================================================
* The Apache Software License, Version 1.1
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* Copyright (c) 2001 The Apache Software Foundation. All rights
* reserved.
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* modification, are permitted provided that the following conditions
* are met:
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* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
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*/
import com.sun.org.apache.bcel.internal.Constants;
import java.io.*;
import java.util.zip.*;
/**
* Wrapper class that parses a given Java .class file. The method <A
* href ="#parse">parse</A> returns a <A href ="JavaClass.html">
* JavaClass</A> object on success. When an I/O error or an
* inconsistency occurs an appropiate exception is propagated back to
* the caller.
*
* The structure and the names comply, except for a few conveniences,
* exactly with the <A href="ftp://java.sun.com/docs/specs/vmspec.ps">
* JVM specification 1.0</a>. See this paper for
* further details about the structure of a bytecode file.
*
* @version $Id: ClassParser.java,v 1.1.2.1 2005/07/31 23:46:27 jeffsuttor Exp $
* @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
*/
public final class ClassParser {
private DataInputStream file;
private ZipFile zip;
private String file_name;
private int class_name_index, superclass_name_index;
private int major, minor; // Compiler version
private int access_flags; // Access rights of parsed class
private int[] interfaces; // Names of implemented interfaces
private ConstantPool constant_pool; // collection of constants
private Field[] fields; // class fields, i.e., its variables
private Method[] methods; // methods defined in the class
private Attribute[] attributes; // attributes defined in the class
private boolean is_zip; // Loaded from zip file
private static final int BUFSIZE = 8192;
/**
* Parse class from the given stream.
*
* @param file Input stream
* @param file_name File name
*/
public ClassParser(InputStream file, String file_name) {
this.file_name = file_name;
String clazz = file.getClass().getName(); // Not a very clean solution ...
is_zip = clazz.startsWith("java.util.zip.") || clazz.startsWith("java.util.jar.");
if(file instanceof DataInputStream) // Is already a data stream
this.file = (DataInputStream)file;
else
this.file = new DataInputStream(new BufferedInputStream(file, BUFSIZE));
}
/** Parse class from given .class file.
*
* @param file_name file name
* @throws IOException
*/
public ClassParser(String file_name) throws IOException
{
is_zip = false;
this.file_name = file_name;
file = new DataInputStream(new BufferedInputStream
(new FileInputStream(file_name), BUFSIZE));
}
/** Parse class from given .class file in a ZIP-archive
*
* @param file_name file name
* @throws IOException
*/
public ClassParser(String zip_file, String file_name) throws IOException
{
is_zip = true;
zip = new ZipFile(zip_file);
ZipEntry entry = zip.getEntry(file_name);
this.file_name = file_name;
file = new DataInputStream(new BufferedInputStream(zip.getInputStream(entry),
BUFSIZE));
}
/**
* Parse the given Java class file and return an object that represents
* the contained data, i.e., constants, methods, fields and commands.
* A <em>ClassFormatException</em> is raised, if the file is not a valid
* .class file. (This does not include verification of the byte code as it
* is performed by the java interpreter).
*
* @return Class object representing the parsed class file
* @throws IOException
* @throws ClassFormatException
*/
public JavaClass parse() throws IOException, ClassFormatException
{
/****************** Read headers ********************************/
// Check magic tag of class file
readID();
// Get compiler version
readVersion();
/****************** Read constant pool and related **************/
// Read constant pool entries
readConstantPool();
// Get class information
readClassInfo();
// Get interface information, i.e., implemented interfaces
readInterfaces();
/****************** Read class fields and methods ***************/
// Read class fields, i.e., the variables of the class
readFields();
// Read class methods, i.e., the functions in the class
readMethods();
// Read class attributes
readAttributes();
// Check for unknown variables
//Unknown[] u = Unknown.getUnknownAttributes();
//for(int i=0; i < u.length; i++)
// System.err.println("WARNING: " + u[i]);
// Everything should have been read now
// if(file.available() > 0) {
// int bytes = file.available();
// byte[] buf = new byte[bytes];
// file.read(buf);
// if(!(is_zip && (buf.length == 1))) {
// System.err.println("WARNING: Trailing garbage at end of " + file_name);
// System.err.println(bytes + " extra bytes: " + Utility.toHexString(buf));
// }
// }
// Read everything of interest, so close the file
file.close();
if(zip != null)
zip.close();
// Return the information we have gathered in a new object
return new JavaClass(class_name_index, superclass_name_index,
file_name, major, minor, access_flags,
constant_pool, interfaces, fields,
methods, attributes, is_zip? JavaClass.ZIP : JavaClass.FILE);
}
/**
* Read information about the attributes of the class.
* @throws IOException
* @throws ClassFormatException
*/
private final void readAttributes() throws IOException, ClassFormatException
{
int attributes_count;
attributes_count = file.readUnsignedShort();
attributes = new Attribute[attributes_count];
for(int i=0; i < attributes_count; i++)
attributes[i] = Attribute.readAttribute(file, constant_pool);
}
/**
* Read information about the class and its super class.
* @throws IOException
* @throws ClassFormatException
*/
private final void readClassInfo() throws IOException, ClassFormatException
{
access_flags = file.readUnsignedShort();
/* Interfaces are implicitely abstract, the flag should be set
* according to the JVM specification.
*/
if((access_flags & Constants.ACC_INTERFACE) != 0)
access_flags |= Constants.ACC_ABSTRACT;
if(((access_flags & Constants.ACC_ABSTRACT) != 0) &&
((access_flags & Constants.ACC_FINAL) != 0 ))
throw new ClassFormatException("Class can't be both final and abstract");
class_name_index = file.readUnsignedShort();
superclass_name_index = file.readUnsignedShort();
}
/**
* Read constant pool entries.
* @throws IOException
* @throws ClassFormatException
*/
private final void readConstantPool() throws IOException, ClassFormatException
{
constant_pool = new ConstantPool(file);
}
/**
* Read information about the fields of the class, i.e., its variables.
* @throws IOException
* @throws ClassFormatException
*/
private final void readFields() throws IOException, ClassFormatException
{
int fields_count;
fields_count = file.readUnsignedShort();
fields = new Field[fields_count];
for(int i=0; i < fields_count; i++)
fields[i] = new Field(file, constant_pool);
}
/******************** Private utility methods **********************/
/**
* Check whether the header of the file is ok.
* Of course, this has to be the first action on successive file reads.
* @throws IOException
* @throws ClassFormatException
*/
private final void readID() throws IOException, ClassFormatException
{
int magic = 0xCAFEBABE;
if(file.readInt() != magic)
throw new ClassFormatException(file_name + " is not a Java .class file");
}
/**
* Read information about the interfaces implemented by this class.
* @throws IOException
* @throws ClassFormatException
*/
private final void readInterfaces() throws IOException, ClassFormatException
{
int interfaces_count;
interfaces_count = file.readUnsignedShort();
interfaces = new int[interfaces_count];
for(int i=0; i < interfaces_count; i++)
interfaces[i] = file.readUnsignedShort();
}
/**
* Read information about the methods of the class.
* @throws IOException
* @throws ClassFormatException
*/
private final void readMethods() throws IOException, ClassFormatException
{
int methods_count;
methods_count = file.readUnsignedShort();
methods = new Method[methods_count];
for(int i=0; i < methods_count; i++)
methods[i] = new Method(file, constant_pool);
}
/**
* Read major and minor version of compiler which created the file.
* @throws IOException
* @throws ClassFormatException
*/
private final void readVersion() throws IOException, ClassFormatException
{
minor = file.readUnsignedShort();
major = file.readUnsignedShort();
}
}