GEP (GDB Enhanced Prompt)

GEP (GDB Enhanced Prompt) is a GDB plug-in which make your GDB command prompt more convenient and flexibility.

Why I need this plug-in?

GDB's original prompt is using hardcoded built-in GNU readline library, we can't add our custom function and key binding easily. The old way to implement them is by patching the GDB's C source code and compiling it again.

But now, you can write your function in Python and use arbitrary key binding easily with GEP without any patching!

And also, GEP has some awesome features already, you can directly use it!

Features

• Ctrl+R for fzf history reverse search
• up-arrow for partial string matching in history
• TAB for auto-completion with floating window
• fish-like autosuggestions
• has the ability to build custom key binding and its callback function by modifying geprc.py

How to install it?

Make sure you have GDB 8.0 or higher compiled with Python3.6+ bindings, then:

1. Install fzf: Installation

2. Download this plug-in and install it:

git clone https://github.com/lebr0nli/GEP.git && \
cd GEP && \
sh install.sh

Note: This plug-in is using prompt-toolkit 2.0.10 (because IDK why prompt-toolkit 3 is not working with GDB Python API), so the install.sh will download prompt_toolkit==2.0.10 to ~/GEP/. Maybe we can build our prompt toolkit just for this plug-in in the future.

3. Add source ~/GEP/.gdbinit-gep to the last line of your ~/.gdbinit

You can run:

echo 'source ~/GEP/.gdbinit-gep' >> ~/.gdbinit

4. Enjoy!

For more configuration

You can modify configuration about history and auto-completion in ~/GEP/.gdbinit-gep.

You can also add your custom key bindings by modifying ~/GEP/geprc.py.

The trade-offs

Since GDB doesn't have a good Python API to fully control and emulate its prompt, this plug-in has some side effects.

However, the side effects are avoidable, here are the guides to avoid them:

gdb.event.before_prompt

The GDB Python API event: gdb.event.before_prompt may be called only once.

So if you are using a GDB plug-in that is listening on this event, this plug-in will cause some bugs.

As far as I know, pwndbg and gef won't be bothered by this side effect now.

To avoid this, you can change the callback function by adding them to gdb.prompt_hook, gdb.prompt_hook has almost the same effects with event.before_prompt, but gdb.prompt_hook can be directed invoke, so this plug-in still can emulate that callback for you!

dont-repeat

When your input is empty and directly press ENTER, GDB will execute the previous command from history if that command doesn't have the property: dont-repeat.

As far as I know, there is no GDB API for checking a command's property.

So, I added some commonly used commands (for original GDB API and GEF) which have that property in a list to avoid repeatedly executing them.

If you have some user-defined function that has dont-repeat property, add your command into the list manually, too.

Note: The list is in .gdbinit-gep.py and the variable name is DONT_REPEAT.

If you found some commands which should or shouldn't be added in that list, let me know on the issue page, thanks!

Bugs, suggestions, and ideas

If you found any bug, or you have any suggestions/ideas about this plug-in, feel free to leave your feedback on the GitHub issue page or send me a pull request!

Thanks!