Voltron

Voltron is an extensible debugger interface written in Python. It allows you to attach utility views to your debugger (LLDB, GDB or VDB) that can retrieve and display data from the debugger host. By running these views in other terminal windows or panes, you can build a customised debugger user interface to suit your needs.

Built-in views are provided for:

• Registers
• Disassembly
• Stack
• Memory
• Breakpoints
• Backtrace

Voltron is built on a JSON/HTTP API which is available over TCP and UNIX domain sockets, and can be used to build custom UI views.

It looks something like this with LLDB:

And this with GDB:

Support

voltron is built primarily for LLDB. GDB and VDB are also supported to some extent.

The following architectures are supported:

	lldb	gdb	vdb
x86	✓	✓	✓
x86_64	✓	✓	✓
arm	✓	✓	✓
arm64	✓	x	x
powerpc	x	✓	x

Installation

A standard python setup script is included.

# python setup.py install

This will install the voltron package and the entry point executable wherever that happens on your system.

Quick Start

1. Configure your debugger to load Voltron when it starts by sourcing the entry.py entry point script. The full path will be inside the voltron package. For example, on OS X it might be /Library/Python/2.7/site-packages/voltron/entry.py.

   For LLDB:

    command script import /path/to/voltron/entry.py
   

   For GDB:

    source /path/to/voltron/entry.py
    voltron init
    set disassembly-flavor intel
   

   This part can go in your .lldbinit or .gdbinit so it's automatically executed when the debugger starts.

   Intel is the only disassembly flavour currently supported for syntax highlighting.

2. Start your debugger. On LLDB you need to call voltron init after you load the inferior, as a target must be loaded before Voltron's hooks can be installed. This means voltron init cannot be called from .lldbinit the way it can from .gdbinit. Hopefully this will be remedied with a more versatile hooking mechanism in a future version of LLDB (this has been discussed with the developers).

    $ lldb file_to_debug
    (lldb) voltron init
   

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

    $ voltron view register
    $ voltron view stack
    $ voltron view disassembly
    $ voltron view backtrace
    $ voltron view command 'reg read'
   

4. Set a breakpoint and run your inferior. Once the inferior has started and the debugger has stopped (either because you interrupted it or because it hit a breakpoint) the views will update.

    (*db) b main
    (*db) run
   

5. The debugger should hit the breakpoint and the views will be updated. A forced update can be triggered with the following command:

    (lldb) voltron stopped
   

Documentation

See the wiki on github.

Bugs

There are some known issues with GDB.

GDB on some distros is built with Python 3, but the system's Python is version 2. If Voltron is installed into Python 2's site-packages it will not work with GDB. See this page on the wiki for installation instructions.

There is no clean way to hook GDB's exit, only the inferior's exit, so the Voltron server is started and stopped along with the inferior. This results in views show "Connection refused" before the inferior has been started.

Due to a limitation in the GDB API, the views are only updated when the debugger is stopped (e.g. by hitting a breakpoint).

If the stack view is causing GDB to hang then it must be launched after the debugger has been launched, the inferior started, and the debugger stopped (e.g. a breakpoint hit). This is due to a GDB bug that has not yet been resolved.

See the issue tracker on github.

License

See the LICENSE file.

If you use this and don't hate it, buy me a beer at a conference some time. This license also extends to other contributors - richo definitely deserves a few beers for his contributions.

Credits

Thanks to Azimuth Security for letting me spend time working on this.

Props to richo for all his contributions to Voltron.

fG!'s gdbinit was the original inspiration for this project.

Thanks to Willi for implementing the VDB support.