Skip to content

README.md

Latest commit

 

History

History
87 lines (62 loc) · 2.55 KB

README.md

File metadata and controls

87 lines (62 loc) · 2.55 KB

Debugging pybison

This is a short introduction in debugging python scripts with gdb.

Install requirements

Install gdb, pyenv and pyenv-virtualenv.

Creating a python debug environment

A debug python version is needed, we use pyenv to install it.

pyenv install -g 3.9.1

Here, we installed python version 3.9.1 with debug symbols (-g). Feel free to choose any other version.

Make sure the installed pyenv python version is accessible, run the following commands:

eval "$(pyenv init -)"
eval "$(pyenv virtualenv-init -)"

Create a virtualenv using the installed debug version:

pyenv virtualenv 3.9.1-debug pybison-d-3.9.1

where 3.9.1-debug is the installed python version with debug symbols (check with pyenv versions what is actually available) and pybison-d-3.9.1 is an arbitrary name for our environment.

Now pyenv virtualenvs lists all the existing environments.

Finally, we activate the created virtualenv

pyenv activate pybison-d-3.9.1

(Note: Later on the virtualenv can be deactivated in the same fashion by executing pyenv deactivate)

Setting up gdb for python

We will extend gdb with some python-aware behavior and python-specific commands by adding the python extension to gdb.

First, the actual python version is needed, against gdb is build. To get the python version used by gdb run gdb --command=checkpython.gdb -ex quit.

The very last line will print the python version used:

sys.version_info(major=3, minor=9, micro=2, releaselevel='final', serial=0)

which shows that the major/minor version is 3.9. Thus, we need to download https://github.com/python/cpython/blob/3.9/Tools/gdb/libpython.py and save it in ~/.config/gdb/libpython.py. (Make sure to choose the right branch/python version if you don't work with 3.9)

Copy the local .gdbinit file to ~/.gdbinit, or integrate it in your current setup.

Setting up pybison

Compile pybison with debug flags

CFLAGS="-O0 -g" CXXFLAGS="-O0 -g" python setup.py install

Debug

Set debug flags for this session:

export CFLAGS="-O0 -g"; export CXXFLAGS="-O0 -g"

To debug a python script run the following:

gdb -ex r --args bash python <programname>.py <arguments>

Note: pyenv install/starts a bash script, so we need to execute bash python

Happy debugging!

Notes

To clean the installed pybison package

python setup.py clean --all

Additionally, every temporary file must be deleted as well, e.g. all dynamic libraries of parsers and compiled grammar / lexer files.