flouri.sh

The JRuby Sandbox is simply a rewrite of why's original sandbox gem in JRuby. It's much less of a hack than the C implementation, and generally considered to be more safe. Here's how I set it up:

1. Download and install the latest JRuby binaries from CodeHaus (I tested with 1.1.5).
2. Download the source of the javasand jruby gem from the JRuby addons project
   svn checkout http://jruby-extras.rubyforge.org/svn/trunk/javasand
3. Compile the gem:
   ant
   BUILD SUCCESSFUL
   If the build fails, it might be because it can't find the JRuby classes. You'll need to find jruby.jar and then add a line to build.xml inside the "build.classpath" path:
   <fileset dir="/path/to/jruby/jars" includes="*.jar" />
4. Package up the gem:
   jgem build javasand.gemspec
5. Install the gem:
   sudo jgem install javasand-0.0.2.gem
6. Test the sandbox with jirb -rubygems

   require "sandbox"
   Sandbox.safe.eval("2+2")
   # yields 4
   

As you can see above, I had to compile the gem from source. The binary gem of javasand from rubyforge failed with the following exception:

irb(main):001:0> require "sandbox"
=> true
irb(main):002:0> Sandbox.safe
org.jruby.ext.sandbox.Sandkit:714:in `removeMethods': java.lang.NoSuchMethodError: org.jruby.RubyModule.removeMethod(Ljava/lang/String;)V