2019-04-04 09:27:23 +01:00
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drgn
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====
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2019-04-11 21:16:48 +01:00
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.. image:: https://travis-ci.org/osandov/drgn.svg?branch=master
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:target: https://travis-ci.org/osandov/drgn
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:alt: Build Status
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2019-04-04 09:27:23 +01:00
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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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.. start-introduction
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2019-04-17 09:18:44 +01:00
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drgn (pronounced "dragon") is a debugger-as-a-library. In contrast to existing
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debuggers like `GDB <https://www.gnu.org/software/gdb/>`_ which focus on
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breakpoint-based debugging, drgn excels in live introspection. drgn exposes the
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types and variables in a program for easy, expressive scripting in Python. For
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example, you can debug the Linux kernel:
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2019-04-04 09:27:23 +01:00
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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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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 planned.
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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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Install the following dependencies:
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* Python 3.6 or newer
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* elfutils development libraries (libelf and libdw)
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* GNU autotools (autoconf, automake, and libtool) and pkgconf
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Then, run:
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.. code-block:: console
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$ git clone https://github.com/osandov/drgn.git
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$ cd drgn
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$ python3 setup.py build
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$ sudo python3 setup.py install
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See the `installation documentation
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<https://drgn.readthedocs.io/en/latest/installation.html>`_ for more details.
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Quick Start
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-----------
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.. start-quick-start
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To debug the running kernel, run ``sudo drgn -k``. To debug a running program,
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run ``sudo drgn -p $PID``. To debug a core dump (either a kernel vmcore or a
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userspace core dump), run ``drgn -c $PATH``. The program must have debugging
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symbols available.
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Then, you can access variables in the program with ``prog['name']``, access
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structure members with ``.``, use various predefined helpers, and more:
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.. code-block:: pycon
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$ sudo drgn -k
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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 2018-2019 Omar Sandoval
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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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