drgn (pronounced "dragon") is a debugger-as-a-library. In contrast to existing debuggers like GDB which focus on breakpoint-based debugging, drgn excels in live introspection. drgn exposes the types and variables in a program for easy, expressive scripting in Python. For example, you can debug the Linux kernel:
>>> 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 )"snd" (char )"evdev" (char )"i915"
drgn was developed for debugging the Linux kernel (as an alternative to the crash utility), but it can also debug userspace programs written in C. C++ support is planned.
Documentation can be found at drgn.readthedocs.io.
Install the following dependencies:
- Python 3.6 or newer
- elfutils development libraries (libelf and libdw)
- GNU autotools (autoconf, automake, and libtool) and pkgconf
$ git clone https://github.com/osandov/drgn.git $ cd drgn $ python3 setup.py build $ sudo python3 setup.py install
See the installation documentation for more details.
To debug the running kernel, run
sudo drgn -k. To debug a running program,
sudo drgn -p $PID. To debug a core dump (either a kernel vmcore or a
userspace core dump), run
drgn -c $PATH. The program must have debugging
Then, you can access variables in the program with
structure members with
., use various predefined helpers, and more:
$ sudo drgn -k >>> prog['init_task'].comm (char )"swapper/0" >>> d_path(fget(find_task(prog, 1), 0).f_path.address_of_()) b'/dev/null' >>> max(task.stime for task in for_each_task(prog)) (u64)4192109975952 >>> sum(disk.gendisk.part0.nr_sects for disk in for_each_disk(prog)) (sector_t)999705952
See the user guide for more information.
Copyright 2018-2019 Omar Sandoval
drgn is licensed under the GPLv3 or later.