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Programmable debugger
eac49edf79
ubuntu-latest was just bumped to Ubuntu 22.04, and actions/setup-python doesn't package Python 3.6 for Ubuntu 22.04. I'd love to drop Python 3.6 support, but some enterprise distros (e.g., CentOS 8) are still on 3.6. So, for now, let's stay on Ubuntu 20.04 so that we can keep testing Python 3.6. Signed-off-by: Omar Sandoval <osandov@osandov.com> |
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.github/workflows | ||
contrib | ||
docs | ||
drgn | ||
libdrgn | ||
LICENSES | ||
scripts | ||
tests | ||
tools | ||
vmtest | ||
_drgn.pyi | ||
.editorconfig | ||
.flake8 | ||
.git-blame-ignore-revs | ||
.gitignore | ||
.packit.yaml | ||
.pre-commit-config.yaml | ||
.readthedocs.yml | ||
CONTRIBUTING.rst | ||
COPYING | ||
MANIFEST.in | ||
pyproject.toml | ||
pytest.ini | ||
README.rst | ||
setup.py | ||
util.py |
drgn ==== .. image:: https://img.shields.io/pypi/v/drgn :target: https://pypi.org/project/drgn/ :alt: PyPI .. image:: https://github.com/osandov/drgn/workflows/CI/badge.svg :target: https://github.com/osandov/drgn/actions :alt: CI Status .. image:: https://readthedocs.org/projects/drgn/badge/?version=latest :target: https://drgn.readthedocs.io/en/latest/?badge=latest :alt: Documentation Status .. image:: https://img.shields.io/badge/code%20style-black-000000.svg :target: https://github.com/psf/black .. start-introduction drgn (pronounced "dragon") is a debugger with an emphasis on programmability. drgn exposes the types and variables in a program for easy, expressive scripting in Python. For example, you can debug the Linux kernel: .. code-block:: pycon >>> from drgn.helpers.linux import list_for_each_entry >>> for mod in list_for_each_entry('struct module', ... prog['modules'].address_of_(), ... 'list'): ... if mod.refcnt.counter > 10: ... print(mod.name) ... (char [56])"snd" (char [56])"evdev" (char [56])"i915" Although other debuggers like `GDB <https://www.gnu.org/software/gdb/>`_ have scripting support, drgn aims to make scripting as natural as possible so that debugging feels like coding. This makes it well-suited for introspecting the complex, inter-connected state in large programs. Additionally, drgn is designed as a library that can be used to build debugging and introspection tools; see the official `tools <https://github.com/osandov/drgn/tree/main/tools>`_. drgn was developed at `Meta <https://opensource.fb.com/>`_ for debugging the Linux kernel (as an alternative to the `crash <https://crash-utility.github.io/>`_ utility), but it can also debug userspace programs written in C. C++ support is in progress. .. end-introduction Documentation can be found at `drgn.readthedocs.io <https://drgn.readthedocs.io>`_. .. start-installation Installation ------------ Package Manager ^^^^^^^^^^^^^^^ drgn can be installed using the package manager on some Linux distributions. .. image:: https://repology.org/badge/vertical-allrepos/drgn.svg :target: https://repology.org/project/drgn/versions :alt: Packaging Status * Fedora >= 32 .. code-block:: console $ sudo dnf install drgn * RHEL/CentOS >= 8 `Enable EPEL <https://docs.fedoraproject.org/en-US/epel/#_quickstart>`_. Then: .. code-block:: console $ sudo dnf install drgn * Arch Linux Install the `drgn <https://aur.archlinux.org/packages/drgn/>`_ package from the `AUR <https://wiki.archlinux.org/title/Arch_User_Repository>`_. * Debian >= 12 (Bookworm) .. code-block:: console $ sudo apt install python3-drgn * openSUSE .. code-block:: console $ sudo zypper install python3-drgn * Ubuntu Enable the `michel-slm/kernel-utils PPA <https://launchpad.net/~michel-slm/+archive/ubuntu/kernel-utils>`_. Then: .. code-block:: console $ sudo apt install python3-drgn pip ^^^ If your Linux distribution doesn't package the latest release of drgn, you can install it with `pip <https://pip.pypa.io/>`_. First, `install pip <https://packaging.python.org/guides/installing-using-linux-tools/#installing-pip-setuptools-wheel-with-linux-package-managers>`_. Then, run: .. code-block:: console $ sudo pip3 install drgn This will install a binary wheel by default. If you get a build error, then pip wasn't able to use the binary wheel. Install the dependencies listed `below <#from-source>`_ and try again. Note that RHEL/CentOS 6, Debian Stretch, Ubuntu Trusty, and Ubuntu Xenial (and older) ship Python versions which are too old. Python 3.6 or newer must be installed. From Source ^^^^^^^^^^^ To get the development version of drgn, you will need to build it from source. First, install dependencies: * Fedora .. code-block:: console $ sudo dnf install autoconf automake elfutils-devel gcc git libkdumpfile-devel libtool make pkgconf python3 python3-devel python3-pip python3-setuptools * RHEL/CentOS .. code-block:: console $ sudo dnf install autoconf automake elfutils-devel gcc git libtool make pkgconf python3 python3-devel python3-pip python3-setuptools Optionally, install ``libkdumpfile-devel`` from EPEL on RHEL/CentOS >= 8 or install `libkdumpfile <https://github.com/ptesarik/libkdumpfile>`_ from source if you want support for the makedumpfile format. Replace ``dnf`` with ``yum`` for RHEL/CentOS < 8. * Debian/Ubuntu .. code-block:: console $ sudo apt-get install autoconf automake gcc git liblzma-dev libelf-dev libdw-dev libtool make pkgconf python3 python3-dev python3-pip python3-setuptools zlib1g-dev Optionally, install libkdumpfile from source if you want support for the makedumpfile format. * Arch Linux .. code-block:: console $ sudo pacman -S --needed autoconf automake gcc git libelf libtool make pkgconf python python-pip python-setuptools Optionally, install `libkdumpfile <https://aur.archlinux.org/packages/libkdumpfile/>`__ from the AUR or from source if you want support for the makedumpfile format. * openSUSE .. code-block:: console $ sudo zypper install autoconf automake gcc git libdw-devel libelf-devel libkdumpfile-devel libtool make pkgconf python3 python3-devel python3-pip python3-setuptools Then, run: .. code-block:: console $ git clone https://github.com/osandov/drgn.git $ cd drgn $ python3 setup.py build $ sudo python3 setup.py install .. end-installation See the `installation documentation <https://drgn.readthedocs.io/en/latest/installation.html>`_ for more options. Quick Start ----------- .. start-quick-start drgn debugs the running kernel by default; run ``sudo drgn``. To debug a running program, run ``sudo drgn -p $PID``. To debug a core dump (either a kernel vmcore or a userspace core dump), run ``drgn -c $PATH``. Make sure to `install debugging symbols <https://drgn.readthedocs.io/en/latest/getting_debugging_symbols.html>`_ for whatever you are debugging. Then, you can access variables in the program with ``prog['name']`` and access structure members with ``.``: .. code-block:: pycon $ sudo drgn >>> prog['init_task'].comm (char [16])"swapper/0" You can use various predefined helpers: .. code-block:: pycon >>> len(list(bpf_prog_for_each(prog))) 11 >>> task = find_task(prog, 115) >>> cmdline(task) [b'findmnt', b'-p'] You can get stack traces with ``prog.stack_trace()`` and access parameters or local variables with ``stack_trace['name']``: .. code-block:: pycon >>> trace = prog.stack_trace(task) >>> trace[5] #5 at 0xffffffff8a5a32d0 (do_sys_poll+0x400/0x578) in do_poll at ./fs/select.c:961:8 (inlined) >>> poll_list = trace[5]['list'] >>> file = fget(task, poll_list.entries[0].fd) >>> d_path(file.f_path.address_of_()) b'/proc/115/mountinfo' .. end-quick-start See the `user guide <https://drgn.readthedocs.io/en/latest/user_guide.html>`_ for more details and features. License ------- .. start-license Copyright (c) Meta Platforms, Inc. and affiliates. drgn is licensed under the `LGPLv2.1 <https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html>`_ or later. .. end-license