src/main/java/org/apache/bcel/classfile/ClassParser.java - commons-bcel - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
  *
  *   https://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  * KIND, either express or implied.  See the License for the
  * specific language governing permissions and limitations
  * under the License.
  */
 package org.apache.bcel.classfile;

 import java.io.BufferedInputStream;
 import java.io.DataInput;
 import java.io.DataInputStream;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;

 import org.apache.bcel.Const;
 import org.apache.commons.io.IOUtils;

 /**
  * 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
  * appropriate exception is propagated back to the caller.
  *
  * The structure and the names comply, except for a few conveniences, exactly with the
  * <a href="https://docs.oracle.com/javase/specs/"> JVM specification 1.0</a>. See this paper for further details about
  * the structure of a bytecode file.
  */
 public final class ClassParser {

     private static final int BUFSIZE = 8192;

     static int[] readU2U2Table(final DataInput dataInput) throws IOException {
         final int count = dataInput.readUnsignedShort();
         final int[] table = new int[count];
         for (int i = 0; i < count; i++) {
             table[i] = dataInput.readUnsignedShort();
         }
         return table;
     }

     private DataInputStream dataInputStream;
     private final boolean fileOwned;
     private final String fileName;
     private String zipFile;
     private int classNameIndex;
     private int superclassNameIndex;
     private int major; // Compiler version
     private int minor; // Compiler version
     private int accessFlags; // Access rights of parsed class
     private int[] interfaces; // Names of implemented interfaces
     private ConstantPool constantPool; // collection of constants
     private Field[] fields; // class fields, that is, its variables
     private Method[] methods; // methods defined in the class
     private Attribute[] attributes; // attributes defined in the class

     private final boolean isZip; // Loaded from ZIP file

     /**
      * Parses class from the given stream.
      *
      * @param inputStream Input stream.
      * @param fileName File name.
      */
     public ClassParser(final InputStream inputStream, final String fileName) {
         this.fileName = fileName;
         this.fileOwned = false;
         final String clazz = inputStream.getClass().getName(); // Not a very clean solution ...
         this.isZip = clazz.startsWith("java.util.zip.") || clazz.startsWith("java.util.jar.");
         if (inputStream instanceof DataInputStream) {
             this.dataInputStream = (DataInputStream) inputStream;
         } else {
             this.dataInputStream = new DataInputStream(new BufferedInputStream(inputStream, BUFSIZE));
         }
     }

     /**
      * Parses class from given .class file.
      *
      * @param fileName file name.
      */
     public ClassParser(final String fileName) {
         this.isZip = false;
         this.fileName = fileName;
         this.fileOwned = true;
     }

     /**
      * Parses class from given .class file in a ZIP-archive
      *
      * @param zipFile ZIP file name.
      * @param fileName file name.
      */
     public ClassParser(final String zipFile, final String fileName) {
         this.isZip = true;
         this.fileOwned = true;
         this.zipFile = zipFile;
         this.fileName = fileName;
     }

     /**
      * Parses the given Java class file and return an object that represents the contained data, that is, 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 if an I/O error occurs.
      * @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
      */
     public JavaClass parse() throws IOException, ClassFormatException {
         ZipFile zip = null;
         try {
             if (fileOwned) {
                 if (isZip) {
                     zip = new ZipFile(zipFile);
                     final ZipEntry entry = zip.getEntry(fileName);

                     if (entry == null) {
                         throw new IOException("File " + fileName + " not found");
                     }

                     dataInputStream = new DataInputStream(new BufferedInputStream(zip.getInputStream(entry), BUFSIZE));
                 } else {
                     dataInputStream = new DataInputStream(new BufferedInputStream(new FileInputStream(fileName), BUFSIZE));
                 }
             }
             // -- 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, that is, implemented interfaces
             readInterfaces();
             // -- Read class fields and methods --
             // Read class fields, that is, the variables of the class
             readFields();
             // Read class methods, that is, 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 (!(isZip && (buf.length == 1))) {
             // System.err.println("WARNING: Trailing garbage at end of " + fileName);
             // System.err.println(bytes + " extra bytes: " + Utility.toHexString(buf));
             // }
             // }
         } finally {
             // Read everything of interest, so close the file
             if (fileOwned) {
                 IOUtils.closeQuietly(dataInputStream);
             }
             IOUtils.closeQuietly(zip);
         }
         // Return the information we have gathered in a new object
         return new JavaClass(classNameIndex, superclassNameIndex, fileName, major, minor, accessFlags, constantPool, interfaces, fields, methods, attributes,
             isZip ? JavaClass.ZIP : JavaClass.FILE);
     }

     /**
      * Reads information about the attributes of the class.
      *
      * @throws IOException if an I/O error occurs.
      * @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
      */
     private void readAttributes() throws IOException, ClassFormatException {
         final int attributesCount = dataInputStream.readUnsignedShort();
         attributes = new Attribute[attributesCount];
         for (int i = 0; i < attributesCount; i++) {
             attributes[i] = Attribute.readAttribute(dataInputStream, constantPool);
         }
     }

     /**
      * Reads information about the class and its super class.
      *
      * @throws IOException if an I/O error occurs.
      * @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
      */
     private void readClassInfo() throws IOException, ClassFormatException {
         accessFlags = dataInputStream.readUnsignedShort();
         /*
          * Interfaces are implicitly abstract, the flag should be set according to the JVM specification.
          */
         if ((accessFlags & Const.ACC_INTERFACE) != 0) {
             accessFlags |= Const.ACC_ABSTRACT;
         }
         if ((accessFlags & Const.ACC_ABSTRACT) != 0 && (accessFlags & Const.ACC_FINAL) != 0) {
             throw new ClassFormatException("Class " + fileName + " can't be both final and abstract");
         }
         classNameIndex = dataInputStream.readUnsignedShort();
         superclassNameIndex = dataInputStream.readUnsignedShort();
     }

     /**
      * Reads constant pool entries.
      *
      * @throws IOException if an I/O error occurs.
      * @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
      */
     private void readConstantPool() throws IOException, ClassFormatException {
         constantPool = new ConstantPool(dataInputStream);
     }

     /**
      * Reads information about the fields of the class, that is, its variables.
      *
      * @throws IOException if an I/O error occurs.
      * @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
      */
     private void readFields() throws IOException, ClassFormatException {
         final int fieldsCount = dataInputStream.readUnsignedShort();
         fields = new Field[fieldsCount];
         for (int i = 0; i < fieldsCount; i++) {
             fields[i] = new Field(dataInputStream, constantPool);
         }
     }

     /**
      * Checks whether the header of the file is ok. Of course, this has to be the first action on successive file reads.
      *
      * @throws IOException if an I/O error occurs.
      * @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
      */
     private void readID() throws IOException, ClassFormatException {
         if (dataInputStream.readInt() != Const.JVM_CLASSFILE_MAGIC) {
             throw new ClassFormatException(fileName + " is not a Java .class file");
         }
     }

     /**
      * Reads information about the interfaces implemented by this class.
      *
      * @throws IOException if an I/O error occurs.
      * @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
      */
     private void readInterfaces() throws IOException, ClassFormatException {
         interfaces = readU2U2Table(dataInputStream);
     }

     /**
      * Reads information about the methods of the class.
      *
      * @throws IOException if an I/O error occurs.
      * @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
      */
     private void readMethods() throws IOException {
         final int methodsCount = dataInputStream.readUnsignedShort();
         methods = new Method[methodsCount];
         for (int i = 0; i < methodsCount; i++) {
             methods[i] = new Method(dataInputStream, constantPool);
         }
     }

     /**
      * Reads major and minor version of compiler which created the file.
      *
      * @throws IOException if an I/O error occurs.
      * @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
      */
     private void readVersion() throws IOException, ClassFormatException {
         minor = dataInputStream.readUnsignedShort();
         major = dataInputStream.readUnsignedShort();
     }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you under the Apache License, Version 2.0 (the
	* "License"); you may not use this file except in compliance
	* with the License. You may obtain a copy of the License at
	*
	* https://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing,
	* software distributed under the License is distributed on an
	* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	* KIND, either express or implied. See the License for the
	* specific language governing permissions and limitations
	* under the License.
	*/
	package org.apache.bcel.classfile;

	import java.io.BufferedInputStream;
	import java.io.DataInput;
	import java.io.DataInputStream;
	import java.io.FileInputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.util.zip.ZipEntry;
	import java.util.zip.ZipFile;

	import org.apache.bcel.Const;
	import org.apache.commons.io.IOUtils;

	/**
	* 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
	* appropriate exception is propagated back to the caller.
	*
	* The structure and the names comply, except for a few conveniences, exactly with the
	* <a href="https://docs.oracle.com/javase/specs/"> JVM specification 1.0</a>. See this paper for further details about
	* the structure of a bytecode file.
	*/
	public final class ClassParser {

	private static final int BUFSIZE = 8192;

	static int[] readU2U2Table(final DataInput dataInput) throws IOException {
	final int count = dataInput.readUnsignedShort();
	final int[] table = new int[count];
	for (int i = 0; i < count; i++) {
	table[i] = dataInput.readUnsignedShort();
	}
	return table;
	}

	private DataInputStream dataInputStream;
	private final boolean fileOwned;
	private final String fileName;
	private String zipFile;
	private int classNameIndex;
	private int superclassNameIndex;
	private int major; // Compiler version
	private int minor; // Compiler version
	private int accessFlags; // Access rights of parsed class
	private int[] interfaces; // Names of implemented interfaces
	private ConstantPool constantPool; // collection of constants
	private Field[] fields; // class fields, that is, its variables
	private Method[] methods; // methods defined in the class
	private Attribute[] attributes; // attributes defined in the class

	private final boolean isZip; // Loaded from ZIP file

	/**
	* Parses class from the given stream.
	*
	* @param inputStream Input stream.
	* @param fileName File name.
	*/
	public ClassParser(final InputStream inputStream, final String fileName) {
	this.fileName = fileName;
	this.fileOwned = false;
	final String clazz = inputStream.getClass().getName(); // Not a very clean solution ...
	this.isZip = clazz.startsWith("java.util.zip.") \|\| clazz.startsWith("java.util.jar.");
	if (inputStream instanceof DataInputStream) {
	this.dataInputStream = (DataInputStream) inputStream;
	} else {
	this.dataInputStream = new DataInputStream(new BufferedInputStream(inputStream, BUFSIZE));
	}
	}

	/**
	* Parses class from given .class file.
	*
	* @param fileName file name.
	*/
	public ClassParser(final String fileName) {
	this.isZip = false;
	this.fileName = fileName;
	this.fileOwned = true;
	}

	/**
	* Parses class from given .class file in a ZIP-archive
	*
	* @param zipFile ZIP file name.
	* @param fileName file name.
	*/
	public ClassParser(final String zipFile, final String fileName) {
	this.isZip = true;
	this.fileOwned = true;
	this.zipFile = zipFile;
	this.fileName = fileName;
	}

	/**
	* Parses the given Java class file and return an object that represents the contained data, that is, 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 if an I/O error occurs.
	* @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
	*/
	public JavaClass parse() throws IOException, ClassFormatException {
	ZipFile zip = null;
	try {
	if (fileOwned) {
	if (isZip) {
	zip = new ZipFile(zipFile);
	final ZipEntry entry = zip.getEntry(fileName);

	if (entry == null) {
	throw new IOException("File " + fileName + " not found");
	}

	dataInputStream = new DataInputStream(new BufferedInputStream(zip.getInputStream(entry), BUFSIZE));
	} else {
	dataInputStream = new DataInputStream(new BufferedInputStream(new FileInputStream(fileName), BUFSIZE));
	}
	}
	// -- 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, that is, implemented interfaces
	readInterfaces();
	// -- Read class fields and methods --
	// Read class fields, that is, the variables of the class
	readFields();
	// Read class methods, that is, 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 (!(isZip && (buf.length == 1))) {
	// System.err.println("WARNING: Trailing garbage at end of " + fileName);
	// System.err.println(bytes + " extra bytes: " + Utility.toHexString(buf));
	// }
	// }
	} finally {
	// Read everything of interest, so close the file
	if (fileOwned) {
	IOUtils.closeQuietly(dataInputStream);
	}
	IOUtils.closeQuietly(zip);
	}
	// Return the information we have gathered in a new object
	return new JavaClass(classNameIndex, superclassNameIndex, fileName, major, minor, accessFlags, constantPool, interfaces, fields, methods, attributes,
	isZip ? JavaClass.ZIP : JavaClass.FILE);
	}

	/**
	* Reads information about the attributes of the class.
	*
	* @throws IOException if an I/O error occurs.
	* @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
	*/
	private void readAttributes() throws IOException, ClassFormatException {
	final int attributesCount = dataInputStream.readUnsignedShort();
	attributes = new Attribute[attributesCount];
	for (int i = 0; i < attributesCount; i++) {
	attributes[i] = Attribute.readAttribute(dataInputStream, constantPool);
	}
	}

	/**
	* Reads information about the class and its super class.
	*
	* @throws IOException if an I/O error occurs.
	* @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
	*/
	private void readClassInfo() throws IOException, ClassFormatException {
	accessFlags = dataInputStream.readUnsignedShort();
	/*
	* Interfaces are implicitly abstract, the flag should be set according to the JVM specification.
	*/
	if ((accessFlags & Const.ACC_INTERFACE) != 0) {
	accessFlags \|= Const.ACC_ABSTRACT;
	}
	if ((accessFlags & Const.ACC_ABSTRACT) != 0 && (accessFlags & Const.ACC_FINAL) != 0) {
	throw new ClassFormatException("Class " + fileName + " can't be both final and abstract");
	}
	classNameIndex = dataInputStream.readUnsignedShort();
	superclassNameIndex = dataInputStream.readUnsignedShort();
	}

	/**
	* Reads constant pool entries.
	*
	* @throws IOException if an I/O error occurs.
	* @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
	*/
	private void readConstantPool() throws IOException, ClassFormatException {
	constantPool = new ConstantPool(dataInputStream);
	}

	/**
	* Reads information about the fields of the class, that is, its variables.
	*
	* @throws IOException if an I/O error occurs.
	* @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
	*/
	private void readFields() throws IOException, ClassFormatException {
	final int fieldsCount = dataInputStream.readUnsignedShort();
	fields = new Field[fieldsCount];
	for (int i = 0; i < fieldsCount; i++) {
	fields[i] = new Field(dataInputStream, constantPool);
	}
	}

	/**
	* Checks whether the header of the file is ok. Of course, this has to be the first action on successive file reads.
	*
	* @throws IOException if an I/O error occurs.
	* @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
	*/
	private void readID() throws IOException, ClassFormatException {
	if (dataInputStream.readInt() != Const.JVM_CLASSFILE_MAGIC) {
	throw new ClassFormatException(fileName + " is not a Java .class file");
	}
	}

	/**
	* Reads information about the interfaces implemented by this class.
	*
	* @throws IOException if an I/O error occurs.
	* @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
	*/
	private void readInterfaces() throws IOException, ClassFormatException {
	interfaces = readU2U2Table(dataInputStream);
	}

	/**
	* Reads information about the methods of the class.
	*
	* @throws IOException if an I/O error occurs.
	* @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
	*/
	private void readMethods() throws IOException {
	final int methodsCount = dataInputStream.readUnsignedShort();
	methods = new Method[methodsCount];
	for (int i = 0; i < methodsCount; i++) {
	methods[i] = new Method(dataInputStream, constantPool);
	}
	}

	/**
	* Reads major and minor version of compiler which created the file.
	*
	* @throws IOException if an I/O error occurs.
	* @throws ClassFormatException if a class is malformed or cannot be interpreted as a class file.
	*/
	private void readVersion() throws IOException, ClassFormatException {
	minor = dataInputStream.readUnsignedShort();
	major = dataInputStream.readUnsignedShort();
	}
	}