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140 lines
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140 lines
4.1 KiB
ReStructuredText
drgn
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====
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.. image:: https://img.shields.io/pypi/v/drgn
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:target: https://pypi.org/project/drgn/
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:alt: PyPI
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.. image:: https://travis-ci.com/osandov/drgn.svg?branch=master
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:target: https://travis-ci.com/osandov/drgn
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:alt: Build Status
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.. image:: https://readthedocs.org/projects/drgn/badge/?version=latest
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:target: https://drgn.readthedocs.io/en/latest/?badge=latest
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:alt: Documentation Status
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.. image:: https://img.shields.io/badge/code%20style-black-000000.svg
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:target: https://github.com/psf/black
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.. start-introduction
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drgn (pronounced "dragon") is a debugger with an emphasis on programmability.
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drgn exposes the types and variables in a program for easy, expressive
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scripting in Python. For example, you can debug the Linux kernel:
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.. code-block:: pycon
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>>> from drgn.helpers.linux import list_for_each_entry
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>>> for mod in list_for_each_entry('struct module',
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... prog['modules'].address_of_(),
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... 'list'):
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... if mod.refcnt.counter > 10:
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... print(mod.name)
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...
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(char [56])"snd"
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(char [56])"evdev"
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(char [56])"i915"
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Although other debuggers like `GDB <https://www.gnu.org/software/gdb/>`_ have
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scripting support, drgn aims to make scripting as natural as possible so that
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debugging feels like coding. This makes it well-suited for introspecting the
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complex, inter-connected state in large programs. It is also designed as a
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library that can be used to build debugging and introspection tools; see the
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official `tools <https://github.com/osandov/drgn/tree/master/tools>`_.
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drgn was developed for debugging the Linux kernel (as an alternative to the
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`crash <http://people.redhat.com/anderson/>`_ utility), but it can also debug
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userspace programs written in C. C++ support is in progress.
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.. end-introduction
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Documentation can be found at `drgn.readthedocs.io
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<https://drgn.readthedocs.io>`_.
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Installation
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------------
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.. start-install-dependencies
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Install dependencies:
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Arch Linux:
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.. code-block:: console
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$ sudo pacman -S --needed autoconf automake bison bzip2 flex gawk gcc libtool make pkgconf python python-setuptools xz zlib
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Debian/Ubuntu:
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.. code-block:: console
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$ sudo apt-get install autoconf automake bison flex gawk gcc libbz2-dev liblzma-dev libtool make pkgconf python3 python3-dev python3-setuptools zlib1g-dev
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Note that Debian Stretch, Ubuntu Trusty, and Ubuntu Xenial (and older) ship
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Python versions which are too old. Python 3.6 or newer must be installed
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manually.
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Fedora:
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.. code-block:: console
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$ sudo dnf install autoconf automake bison bzip2-devel flex gawk gcc libtool make pkgconf python3 python3-devel python3-setuptools xz-devel zlib-devel
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Optionally, install:
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* `libkdumpfile <https://github.com/ptesarik/libkdumpfile>`_ if you want
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support for kdump-compressed kernel core dumps
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.. end-install-dependencies
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Then, run:
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.. code-block:: console
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$ sudo pip3 install drgn
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See the `installation documentation
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<https://drgn.readthedocs.io/en/latest/installation.html>`_ for more options.
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Quick Start
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-----------
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.. start-quick-start
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drgn debugs the running kernel by default; run ``sudo drgn``. To debug a
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running program, run ``sudo drgn -p $PID``. To debug a core dump (either a
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kernel vmcore or a userspace core dump), run ``drgn -c $PATH``. The program
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must have debugging symbols available.
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Then, you can access variables in the program with ``prog['name']``, access
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structure members with ``.``, use various predefined helpers, and more:
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.. code-block:: pycon
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$ sudo drgn
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>>> prog['init_task'].comm
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(char [16])"swapper/0"
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>>> d_path(fget(find_task(prog, 1), 0).f_path.address_of_())
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b'/dev/null'
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>>> max(task.stime for task in for_each_task(prog))
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(u64)4192109975952
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>>> sum(disk.gendisk.part0.nr_sects for disk in for_each_disk(prog))
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(sector_t)999705952
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.. end-quick-start
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See the `user guide <https://drgn.readthedocs.io/en/latest/user_guide.html>`_
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for more information.
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License
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-------
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.. start-license
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Copyright (c) Facebook, Inc. and its affiliates.
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drgn is licensed under the `GPLv3
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<https://www.gnu.org/licenses/gpl-3.0.en.html>`_ or later.
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.. end-license
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