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:
>>> 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 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. It is also designed as a library that can be used to build debugging and introspection tools; see the official tools.
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 in progress.
Documentation can be found at drgn.readthedocs.io.
Installation
Install dependencies:
Arch Linux:
$ sudo pacman -S --needed gcc libelf make pkgconf python python-pip python-setuptoolsDebian/Ubuntu:
$ sudo apt-get install gcc liblzma-dev libelf-dev libdw-dev make pkgconf python3 python3-dev python3-pip python3-setuptools zlib1g-devNote that Debian Stretch, Ubuntu Trusty, and Ubuntu Xenial (and older) ship Python versions which are too old. Python 3.6 or newer must be installed manually.
Fedora:
$ sudo dnf install elfutils-devel gcc make pkgconf python3 python3-devel python3-pip python3-setuptoolsOptionally, install:
libkdumpfile if you want support for kdump-compressed kernel core dumps
Then, run:
$ sudo pip3 install drgnSee the installation documentation for more options.
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. The program must have debugging symbols available.
Then, you can access variables in the program with prog['name'] and access structure members with .:
$ sudo drgn
>>> prog['init_task'].comm
(char [16])"swapper/0"You can use various predefined helpers:
>>> 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']:
>>> 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'See the user guide for more details and features.
License
Copyright (c) Facebook, Inc. and its affiliates.
drgn is licensed under the GPLv3 or later.
1 maintainer
Metadata
1 maintainer
Release files for drgn 0.0.14
For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.
Source distribution (sdist)
| File | Size | Uploaded | |
|---|---|---|---|
| drgn-0.0.14.tar.gz | 856.0 kB | Details |
Built distributions (wheels)
| File | Reset | |||
|---|---|---|---|---|
| drgn-0.0.14-cp310-cp310-manylinux_2_12_x86_64.manylinux2010_x86_64.whl | CPython 3.10 | CPython 3.10 | Linux glibc 2.12+ x86-64 | Details |
| drgn-0.0.14-cp39-cp39-manylinux_2_12_x86_64.manylinux2010_x86_64.whl | CPython 3.9 | CPython 3.9 | Linux glibc 2.12+ x86-64 | Details |
| drgn-0.0.14-cp38-cp38-manylinux_2_12_x86_64.manylinux2010_x86_64.whl | CPython 3.8 | CPython 3.8 | Linux glibc 2.12+ x86-64 | Details |
| drgn-0.0.14-cp37-cp37m-manylinux_2_12_x86_64.manylinux2010_x86_64.whl | CPython 3.7 | CPython 3.7 pymalloc | Linux glibc 2.12+ x86-64 | Details |
| drgn-0.0.14-cp36-cp36m-manylinux_2_12_x86_64.manylinux2010_x86_64.whl | CPython 3.6 | CPython 3.6 pymalloc | Linux glibc 2.12+ x86-64 | Details |
Total release size: 21.3 MB
Release files / drgn-0.0.14.tar.gz
| Download URL | drgn-0.0.14.tar.gz |
|---|---|
| Size | 856.0 kB |
| Tags | Source |
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Release files / drgn-0.0.14-cp310-cp310-manylinux_2_12_x86_64.manylinux2010_x86_64.whl
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Release files / drgn-0.0.14-cp39-cp39-manylinux_2_12_x86_64.manylinux2010_x86_64.whl
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Release files / drgn-0.0.14-cp38-cp38-manylinux_2_12_x86_64.manylinux2010_x86_64.whl
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Release files / drgn-0.0.14-cp37-cp37m-manylinux_2_12_x86_64.manylinux2010_x86_64.whl
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Release files / drgn-0.0.14-cp36-cp36m-manylinux_2_12_x86_64.manylinux2010_x86_64.whl
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