How to debug a Python C extension with GDBFrontend

Hi, in this tutorial, I'm going to show you how to debug a native C Python extension.

Installing Python3 debug symbols

To debug Python3, you need debug symbols for it.

On Debian:

sudo apt install python3-dbg

I have no idea about other distros. Just search about "Python debug symbols on DISTRO"

Build your extension with debug symbols

Just set CFLAGS environment variables:

CFLAGS="-O0 -g" python3 setup.py build

Let's debug!

First thing, we are going to start GDBFrontend:

gdbfrontend

GDBFrontend will open a browser tab as a default behavior but if it doesn't happen, you can open the app URL:

http://127.0.0.1:5550/terminal/

Optionally you can run it as a Chrome/Chromium app:

chrome --app=http://127.0.0.1:5550/terminal/

Optionally choose the Doki Theme xD

We just need to add split the terminal and start a Python3 interpeter on the right side.

To attach GDB to our Python3 process, we need PID of our Python PID.

>>> import os
>>> os.getpid()
25524

And on GDB shell:

(gdb) attach 25524

At this point, GDB will immediately stop the process. Just click to continue button (the second button on top) or press F6.

Import your module on Python prompt and unfocus from terminal, now just press Ctrl + P shortcut and type a source name from your Python extension.

Congratulations! Now you can add a breakpoint to a function from your extension and use that function!