aoqi@0: /*
aoqi@0:  * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.  Oracle designates this
aoqi@0:  * particular file as subject to the "Classpath" exception as provided
aoqi@0:  * by Oracle in the LICENSE file that accompanied this code.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  */
aoqi@0: 
aoqi@0: package com.sun.xml.internal.bind.v2.bytecode;
aoqi@0: 
aoqi@0: import java.io.ByteArrayOutputStream;
aoqi@0: import java.io.DataInputStream;
aoqi@0: import java.io.DataOutputStream;
aoqi@0: import java.io.IOException;
aoqi@0: import java.io.InputStream;
aoqi@0: import java.util.logging.Level;
aoqi@0: import java.util.logging.Logger;
aoqi@0: 
aoqi@0: import com.sun.xml.internal.bind.Util;
aoqi@0: 
aoqi@0: /**
aoqi@0:  * Replaces a few constant pool tokens from a class "template" and then loads it into the VM.
aoqi@0:  *
aoqi@0:  * @author Kohsuke Kawaguchi
aoqi@0:  */
aoqi@0: public final class ClassTailor {
aoqi@0: 
aoqi@0:     private ClassTailor() {} // no instanciation please
aoqi@0: 
aoqi@0:     private static final Logger logger = Util.getClassLogger();
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Returns the class name in the JVM format (such as "java/lang/String")
aoqi@0:      */
aoqi@0:     public static String toVMClassName( Class c ) {
aoqi@0:         assert !c.isPrimitive();
aoqi@0:         if(c.isArray())
aoqi@0:             // I have no idea why it is designed like this, but javap says so.
aoqi@0:             return toVMTypeName(c);
aoqi@0:         return c.getName().replace('.','/');
aoqi@0:     }
aoqi@0: 
aoqi@0:     public static String toVMTypeName( Class c ) {
aoqi@0:         if(c.isArray()) {
aoqi@0:             // TODO: study how an array type is encoded.
aoqi@0:             return '['+toVMTypeName(c.getComponentType());
aoqi@0:         }
aoqi@0:         if(c.isPrimitive()) {
aoqi@0:             if(c==Boolean.TYPE)     return "Z";
aoqi@0:             if(c==Character.TYPE)   return "C";
aoqi@0:             if(c==Byte.TYPE)        return "B";
aoqi@0:             if(c==Double.TYPE)      return "D";
aoqi@0:             if(c==Float.TYPE)       return "F";
aoqi@0:             if(c==Integer.TYPE)     return "I";
aoqi@0:             if(c==Long.TYPE)        return "J";
aoqi@0:             if(c==Short.TYPE)       return "S";
aoqi@0: 
aoqi@0:             throw new IllegalArgumentException(c.getName());
aoqi@0:         }
aoqi@0:         return 'L'+c.getName().replace('.','/')+';';
aoqi@0:     }
aoqi@0: 
aoqi@0: 
aoqi@0: 
aoqi@0:     public static byte[] tailor( Class templateClass, String newClassName, String... replacements ) {
aoqi@0:         String vmname = toVMClassName(templateClass);
aoqi@0:         return tailor(
aoqi@0:             SecureLoader.getClassClassLoader(templateClass).getResourceAsStream(vmname+".class"),
aoqi@0:             vmname, newClassName, replacements );
aoqi@0:     }
aoqi@0: 
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Customizes a class file by replacing constant pools.
aoqi@0:      *
aoqi@0:      * @param image
aoqi@0:      *      The image of the template class.
aoqi@0:      * @param replacements
aoqi@0:      *      A list of pair of strings that specify the substitution
aoqi@0:      *      {@code String[]{search_0, replace_0, search_1, replace_1, ..., search_n, replace_n }}
aoqi@0:      *
aoqi@0:      *      The search strings found in the constant pool will be replaced by the corresponding
aoqi@0:      *      replacement string.
aoqi@0:      */
aoqi@0:     public static byte[] tailor( InputStream image, String templateClassName, String newClassName, String... replacements ) {
aoqi@0:         DataInputStream in = new DataInputStream(image);
aoqi@0: 
aoqi@0:         try {
aoqi@0:             ByteArrayOutputStream baos = new ByteArrayOutputStream(1024);
aoqi@0:             DataOutputStream out = new DataOutputStream(baos);
aoqi@0: 
aoqi@0:             // skip until the constant pool count
aoqi@0:             long l = in.readLong();
aoqi@0:             out.writeLong(l);
aoqi@0: 
aoqi@0:             // read the constant pool size
aoqi@0:             short count = in.readShort();
aoqi@0:             out.writeShort(count);
aoqi@0: 
aoqi@0:             // replace constant pools
aoqi@0:             for( int i=0; i<count; i++ ) {
aoqi@0:                 byte tag = in.readByte();
aoqi@0:                 out.writeByte(tag);
aoqi@0:                 switch(tag) {
aoqi@0:                 case 0:
aoqi@0:                     // this isn't described in the spec,
aoqi@0:                     // but class files often seem to have this '0' tag.
aoqi@0:                     // we can apparently just ignore it, but not sure
aoqi@0:                     // what this really means.
aoqi@0:                     break;
aoqi@0: 
aoqi@0:                 case 1: // CONSTANT_UTF8
aoqi@0:                     {
aoqi@0:                         String value = in.readUTF();
aoqi@0:                         if(value.equals(templateClassName))
aoqi@0:                             value = newClassName;
aoqi@0:                         else {
aoqi@0:                             for( int j=0; j<replacements.length; j+=2 )
aoqi@0:                                 if(value.equals(replacements[j])) {
aoqi@0:                                     value = replacements[j+1];
aoqi@0:                                     break;
aoqi@0:                                 }
aoqi@0:                         }
aoqi@0:                         out.writeUTF(value);
aoqi@0:                     }
aoqi@0:                 break;
aoqi@0: 
aoqi@0:                 case 3: // CONSTANT_Integer
aoqi@0:                 case 4: // CONSTANT_Float
aoqi@0:                     out.writeInt(in.readInt());
aoqi@0:                     break;
aoqi@0: 
aoqi@0:                 case 5: // CONSTANT_Long
aoqi@0:                 case 6: // CONSTANT_Double
aoqi@0:                     i++; // doubles and longs take two entries
aoqi@0:                     out.writeLong(in.readLong());
aoqi@0:                     break;
aoqi@0: 
aoqi@0:                 case 7: // CONSTANT_Class
aoqi@0:                 case 8: // CONSTANT_String
aoqi@0:                     out.writeShort(in.readShort());
aoqi@0:                     break;
aoqi@0: 
aoqi@0:                 case 9: // CONSTANT_Fieldref
aoqi@0:                 case 10: // CONSTANT_Methodref
aoqi@0:                 case 11: // CONSTANT_InterfaceMethodref
aoqi@0:                 case 12: // CONSTANT_NameAndType
aoqi@0:                     out.writeInt(in.readInt());
aoqi@0:                     break;
aoqi@0: 
aoqi@0:                 default:
aoqi@0:                     throw new IllegalArgumentException("Unknown constant type "+tag);
aoqi@0:                 }
aoqi@0:             }
aoqi@0: 
aoqi@0:             // then copy the rest
aoqi@0:             byte[] buf = new byte[512];
aoqi@0:             int len;
aoqi@0:             while((len=in.read(buf))>0)
aoqi@0:                 out.write(buf,0,len);
aoqi@0: 
aoqi@0:             in.close();
aoqi@0:             out.close();
aoqi@0: 
aoqi@0:             // by now we got the properly tailored class file image
aoqi@0:             return baos.toByteArray();
aoqi@0: 
aoqi@0:         } catch( IOException e ) {
aoqi@0:             // never happen
aoqi@0:             logger.log(Level.WARNING,"failed to tailor",e);
aoqi@0:             return null;
aoqi@0:         }
aoqi@0:     }
aoqi@0: }