voltron

A half-arsed UI module for GDB & LLDB.

I got sick of GDB's (lack of) UI, so I built this. fG!'s gdbinit makes GDB slightly more bearable, and this does a similar job in a different way. voltron allows you to attach views running in other terminal windows to a GDB session, resulting in a more modular and flexible UI like you get in a GUI debugger like WinDbg, Immunity Debugger, OllyDbg, etc. It's not in the same league as a proper GUI debugger, but it does make GDB more bearable.

I initially built this to work with GDB but with the idea that I'd add LLDB support at some point. That point is now! Voltron now works with LLDB as well.

It's basically held together by sticky tape, so don't expect too much.

Requirements

voltron supports GDB version 7, LLDB, and has limited support for GDB version 6.

Usage - GDBv7

1. Load voltron into your debugger (this could go in your .gdbinit)

    source /path/to/voltron.py
   

2. Fire up the debugger and start the voltron server thread (you could also put this in your .gdbinit)

    $ gdb whatever
    gdb$ voltron start
   

3. In another terminal (I use iTerm panes) start one of the UI views

    $ voltron.py reg -v
    $ voltron.py stack
    $ voltron.py disasm
    $ voltron.py bt
    $ voltron.py cmd 'x/32x $rip'
   

4. The UI view code will attach to the server (via a domain socket) and refresh every time the debugger is stopped. So, set a break point and let the debugger hit it and everything should be updated. A forced update can be triggered with the following command:

    gdb$ voltron update
   

5. Before you exit the debugger, execute the following command or GDB will hang since the domain socket will still be open.

    gdb$ voltron stop
   

Usage - GDBv6

Note: voltron only has limited support for GDBv6 as it's tough to get useful data out of GDB without the Python API. A set of GDB macros are included to interact with voltron (which in this case runs as a background process started by the voltron_start macro). Only the register and stack views are supported.

A hook-stop macro is included - if you have your own custom one (e.g. fG!'s) you should just add voltron_update to your own and comment out the one in voltron.gdb

1. Load the macros into your debugger (this could go in your .gdbinit)

    source /path/to/voltron.gdb
   

2. Fire up the debugger and start the voltron server thread (you could also put this in your .gdbinit)

    $ gdb whatever
    gdb$ voltron_start
   

3. In another terminal (I use iTerm panes) start one of the UI views

    $ voltron.py reg -v
    $ voltron.py stack
   

4. The UI view code will attach to the server (via a domain socket) and refresh every time the debugger is stopped. So, set a break point and let the debugger hit it and everything should be updated. A forced update can be triggered with the following command:

    gdb$ voltron_update
   

5. Before you exit the debugger, execute the following command the server process will be left running in the background.

    gdb$ voltron_stop
   

Usage - LLDB

1. Load voltron into your debugger (this could go in your .lldbinit)

    command script import /path/to/voltron.py
   

2. Fire up the debugger and start the voltron server thread (you could also put this in your .lldbinit)

    $ lldb whatever
    (lldb) voltron start
   

3. In another terminal (I use iTerm panes) start one of the UI views

    $ voltron.py reg -v
    $ voltron.py stack
    $ voltron.py disasm
    $ voltron.py bt
    $ voltron.py cmd 'reg read'
   

4. The UI view code will attach to the server (via a domain socket) and refresh every time the debugger is stopped. So, set a break point and let the debugger hit it and everything should be updated. A forced update can be triggered with the following command:

    (lldb) voltron update
   

Bugs

If you don't voltron stop before you try to exit GDB the domain socket remains open, and GDB will hang. I couldn't see a hook in the python API to get a notification when GDB is about to exit. It's probably there, but I'll fix it later. Maybe.

There are probably others.

Development

I initially hacked this together in a night as a "do the bare minimum to make my life better" project, as larger projects of this nature that I start never get finished. A few people have expressed interest in it, so I've added a few bits and pieces to it and will probably continue to add to it occasionally.

Things I probably will do at some stage in the not too distant future:

• Better colour support throughout all views like in the register view
• Move a bunch of the colour and template stuff to a config file
• Do something better than use Pygments with the sucky GDB lexer

Feel free to add to it and send a pull request.

If you want to add a new view type you'll just need to add a new subclass of VoltronView (see the others for examples) that registers for updates and renders data for your own message type, and potentially add some code to VoltronCommand/VoltronGDBCommand/VoltronLLDBCommand to grab the necessary data and cram it into an update message.

License

This software is released under the "Buy snare a beer" license. If you use this and don't hate it, buy me a beer at a conference some time.

FAQ

Q: Dude, why don't you just use X?

A: IDA's debugger doesn't work with Y, LLDB doesn't work with Z, none of the GDB UIs are any good for assembly-level debugging, and I don't use Windows.