Unrubby is a hacked up rubby interpreter. In addition to parsing and evaluating rubby code, it will dump a decompiled copy of any bytecode evaluated to stdout upon exiting.

You'll want to configure with something akin to:

./configure --prefix=$(pwd) --disable-install-doc

There's a Makefile in the toplevel of unrubby that will likely do something plausible looking for you, if you prefer.

In short, just invoke bin/unrubby instead of ruby. You almost certainly want to

export UNRUBBY_METHODS=1

Which will invoke the method disasembler, which is definitely what you want unless you just want a classmap.

Experimental support for disasembling entire ISeq's is hidden behind UNRUBBY_FULL_ISEQ.

When invoked as unrubby, unrubby will attempt to automatically load its paired copy of reversal, but if you have moved things around, simply passing

unrubby -r path/to/bundled/reversal/lib/reversal.rb

Should give you the disasembler you need.

If you want to suppress the automatic load (Because, eg, you want to require dependencies for the application without dissembling them and making your dump horrendously huge):

export UNRUBBY_DEFER_REVERSAL=1

If you really don't want whatever it is you're poking to talk to the network;

export UNRUBBY_SOCKET_HACK=1

This won't protect you from shared objects knowing how to socket(3), raw syscalls, etc. It's also a pretty blunt hammer, but defining a Socket with some method_missing glue won't be too hard.

There's a stub that will bring up most of a rails app in etc. Additionally, if you

export UNRUBBY_STUBS=1

It will duck punch Object right in the face and make most any attempts to poke at other classes succeed. Note that this will break attempts to include or extend modules, you will need to define them yourself.

unrubby isn't perfect, and probably has a lot of lowhanging fruit right now. If you run into crashes (InternalDecompilerErrors), there's a reporting mode that'll cough up enough information for me to probably fix it. It's documented in more detail in reporting bugs