Skip to content

Instantly share code, notes, and snippets.

@VijayKrishna

VijayKrishna/ReturnAdapter.java

Last active September 8, 2023 19:53
Show Gist options

  • Select an option

    Learn more about clone URLs
  • Save VijayKrishna/1ca807c952187a7d8c4d to your computer and use it in GitHub Desktop.

Select an option

Learn more about clone URLs
Save VijayKrishna/1ca807c952187a7d8c4d to your computer and use it in GitHub Desktop.
Download ZIP

Revisions

  1. VijayKrishna revised this gist May 26, 2014. 1 changed file with 16 additions and 1 deletion.
    17 changes: 16 additions & 1 deletion ReturnAdapter.java
    View file
    Original file line number Diff line number Diff line change
    @@ -11,6 +11,12 @@
    import org.objectweb.asm.Opcodes;
    import org.objectweb.asm.commons.AdviceAdapter;

    /**
    * Class visitor that adapts a java class to insert code before
    * the return instructions in the methods of the class.
    * @author vijay
    *
    */
    public class ReturnAdapter extends ClassVisitor {
    private String className;

    @@ -37,13 +43,21 @@ public static void main(String[] args) throws IOException {
    File inFile = new File(classFile);
    FileInputStream in = new FileInputStream(inFile);

    // adapting the class.
    ClassReader cr = new ClassReader(in);
    ClassWriter cw = new ClassWriter(ClassReader.EXPAND_FRAMES);
    ReturnAdapter returnAdapter = new ReturnAdapter(cw, className);
    ReturnAdapter returnAdapter = new ReturnAdapter(cw, className);
    cr.accept(returnAdapter, 0);
    }
    }

    /**
    * Method Visitor that inserts code right before its return instruction(s),
    * using the onMethodExit(int opcode) method of the AdviceAdapter class,
    * from ASM(.ow2.org).
    * @author vijay
    *
    */
    class MethodReturnAdapter extends AdviceAdapter {
    public MethodReturnAdapter(
    int api,
    @@ -67,6 +81,7 @@ public MethodReturnAdapter(
    protected void onMethodExit(int opcode) {
    if(opcode != Opcodes.ATHROW) {
    mv.visitVarInsn(Opcodes.ALOAD, 42);
    // and/or any other visit instructions.
    }
    }
    }
  2. VijayKrishna created this gist May 26, 2014.
    72 changes: 72 additions & 0 deletions ReturnAdapter.java
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,72 @@
    package self.vpalepu.stackoverflow;

    import java.io.File;
    import java.io.FileInputStream;
    import java.io.IOException;

    import org.objectweb.asm.ClassReader;
    import org.objectweb.asm.ClassVisitor;
    import org.objectweb.asm.ClassWriter;
    import org.objectweb.asm.MethodVisitor;
    import org.objectweb.asm.Opcodes;
    import org.objectweb.asm.commons.AdviceAdapter;

    public class ReturnAdapter extends ClassVisitor {
    private String className;

    public ReturnAdapter(ClassVisitor cv, String className) {
    super(Opcodes.ASM4, cv);
    }

    @Override
    public MethodVisitor visitMethod(
    int access,
    String name,
    String desc,
    String signature,
    String[] exceptions) {
    MethodVisitor mv;
    mv = cv.visitMethod(access, name, desc, signature, exceptions);
    mv = new MethodReturnAdapter(Opcodes.ASM4, className, access, name, desc, mv);
    return mv;
    }

    public static void main(String[] args) throws IOException {
    String classFile = args[0];//path of the class file
    String className = args[1];//name of the class
    File inFile = new File(classFile);
    FileInputStream in = new FileInputStream(inFile);

    ClassReader cr = new ClassReader(in);
    ClassWriter cw = new ClassWriter(ClassReader.EXPAND_FRAMES);
    ReturnAdapter returnAdapter = new ReturnAdapter(cw, className);
    cr.accept(returnAdapter, 0);
    }
    }

    class MethodReturnAdapter extends AdviceAdapter {
    public MethodReturnAdapter(
    int api,
    String owner,
    int access,
    String name,
    String desc,
    MethodVisitor mv) {
    super(Opcodes.ASM4, mv, access, name, desc);
    }

    public MethodReturnAdapter(
    MethodVisitor mv,
    int access,
    String name,
    String desc) {
    super(Opcodes.ASM4, mv, access, name, desc);
    }

    @Override
    protected void onMethodExit(int opcode) {
    if(opcode != Opcodes.ATHROW) {
    mv.visitVarInsn(Opcodes.ALOAD, 42);
    }
    }
    }