JvmVM

A Java VM on top of JVM.

Target of this project is to create sandbox for user java code execution with control over instructions and save/load running program.

To run VM you just need to create and compile project:

Project project = new Project("Name")
    .addFiles(mapWithFileNamesAsKeysAndTheirContentsAsValues)
    .addSystemClasses(listOfSystemClassesThatYouAllowToUseInVm)
    .compile()
    .setupVM("pkg.ClassName", "methodName");

This will start execution of static method on given class.

JvmVM virtualizes jvm stack and instructions execution for given code. And then you can execute instructions:

while (project.isActive()) {
    project.step();
}
Object result = project.getResult();

or to execute until return:

Object result = project.run();

Breakpoints

You can manage breakpoints to stop execution at needed point:

project.setBreakpoint("pkg/ClassName.java", 15);
project.setBreakpoint("pkg.ClassName", "methodName");
project.removeBreakpoint("pkg/ClassName.java", 20);
try{
    Object result = project.run();
} catch(ProjectBreakpointException e) {
    // ...
}
project.clearBreakpoints();

Data manipulation

VM has ability to mainpulate values of static objects and in stack:

int x = project.getLocalVariable("x");
project.setLocalVariable("x", x + 1);

Object obj = project.getStaticField("pkg.ClassName", "fieldName");
project.setStaticField("pkg.ClassName", "fieldName", obj2);

Save / Load

Executed programs must use only serializable system classes for ability of VM serialization. User classes made serializable by classloader.

byte[] serializedProject = project.saveToBytes();
Project restoredProject = Project.fromBytes(serializedProject);
restoredProject.run();

You can continue running restored project as if it is a new separate project, stopped at same point as original.

In Development

Project is in alpha and contains bugs, undocumented features and documentation for unwritten features. See tests http://git.io/4hc3tA and source code http://git.io/V6UvpA.

Authors and Contributors

Original project is JauVM - http://jauvm.blogspot.ru/. To achieve full functionality original classes were modified and additional utilities were added.

Support or Contact

Contact me: vladimir.p.polyakov@gmail.com.