drgn

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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.

Additionally, drgn is designed as a library that can be used to build debugging and introspection tools; see the official tools.

drgn was developed at Meta 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

Package Manager

drgn can be installed using the package manager on some Linux distributions.

Fedora >= 32
```
$ sudo dnf install drgn
```
RHEL/CentOS >= 8

Enable EPEL. Then:
```
$ sudo dnf install drgn
```
Arch Linux

Install the drgn package from the AUR.
Debian >= 12 (Bookworm)
```
$ sudo apt install python3-drgn
```
openSUSE
```
$ sudo zypper install python3-drgn
```
Ubuntu

Enable the michel-slm/kernel-utils PPA. Then:
```
$ sudo apt install python3-drgn
```

pip

If your Linux distribution doesn’t package the latest release of drgn, you can install it with pip.

First, install pip. Then, run:

$ 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 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

$ sudo dnf install autoconf automake elfutils-devel gcc git libkdumpfile-devel libtool make pkgconf python3 python3-devel python3-pip python3-setuptools

RHEL/CentOS
```
$ 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 from source if you want support for the makedumpfile format.

Replace dnf with yum for RHEL/CentOS < 8.

Debian/Ubuntu

$ 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

$ sudo pacman -S --needed autoconf automake gcc git libelf libtool make pkgconf python python-pip python-setuptools

Optionally, install libkdumpfile from the AUR or from source if you want support for the makedumpfile format.

openSUSE

$ 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:

$ 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 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. Make sure to install debugging symbols for whatever you are debugging.

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()))
11
>>> task = find_task(115)
>>> cmdline(task)
[b'findmnt', b'-p']

You can get stack traces with stack_trace() and access parameters or local variables with trace['name']:

>>> trace = 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

drgn is licensed under the LGPLv2.1 or later.

Metadata

Release files for drgn 0.0.25

For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.

Source distribution (sdist)

Source distribution for drgn 0.0.25
File	Size	Uploaded
drgn-0.0.25.tar.gz	1.1 MB	Dec 1, 2023	Details

Built distributions (wheels)

Table of built distributions (wheels) for drgn 0.0.25
File	Interpreter	ABI	Platform	Reset
drgn-0.0.25-cp312-cp312-manylinux_2_17_x86_64.manylinux2014_x86_64.whl 4.5 MB Dec 1, 2023	CPython 3.12	CPython 3.12	Linux glibc 2.17+ x86-64	Details
drgn-0.0.25-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl 4.5 MB Dec 1, 2023	CPython 3.11	CPython 3.11	Linux glibc 2.17+ x86-64	Details
drgn-0.0.25-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl 4.5 MB Dec 1, 2023	CPython 3.10	CPython 3.10	Linux glibc 2.17+ x86-64	Details
drgn-0.0.25-cp39-cp39-manylinux_2_17_x86_64.manylinux2014_x86_64.whl 4.5 MB Dec 1, 2023	CPython 3.9	CPython 3.9	Linux glibc 2.17+ x86-64	Details
drgn-0.0.25-cp38-cp38-manylinux_2_17_x86_64.manylinux2014_x86_64.whl 4.5 MB Dec 1, 2023	CPython 3.8	CPython 3.8	Linux glibc 2.17+ x86-64	Details
drgn-0.0.25-cp37-cp37m-manylinux_2_17_x86_64.manylinux2014_x86_64.whl 4.5 MB Dec 1, 2023	CPython 3.7	CPython 3.7 pymalloc	Linux glibc 2.17+ x86-64	Details
drgn-0.0.25-cp36-cp36m-manylinux_2_17_x86_64.manylinux2014_x86_64.whl 4.5 MB Dec 1, 2023	CPython 3.6	CPython 3.6 pymalloc	Linux glibc 2.17+ x86-64	Details

Total release size: 32.6 MB

Release files / drgn-0.0.25.tar.gz

Download URL	drgn-0.0.25.tar.gz
Size	1.1 MB
Tags	Source
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Upload date	Dec 1, 2023
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Uploaded via	`twine/4.0.1 CPython/3.12.0`

Release files / drgn-0.0.25-cp312-cp312-manylinux_2_17_x86_64.manylinux2014_x86_64.whl

Download URL	drgn-0.0.25-cp312-cp312-manylinux_2_17_x86_64.manylinux2014_x86_64.whl
Size	4.5 MB
Tags	CPython 3.12 Linux glibc 2.17+ x86-64
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Upload date	Dec 1, 2023
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Uploaded via	`twine/4.0.1 CPython/3.12.0`

Release files / drgn-0.0.25-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl

Download URL	drgn-0.0.25-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl
Size	4.5 MB
Tags	CPython 3.11 Linux glibc 2.17+ x86-64
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Upload date	Dec 1, 2023
Uploaded using Trusted Publishing? What is trusted publishing?	No
Uploaded via	`twine/4.0.1 CPython/3.12.0`

Release files / drgn-0.0.25-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl

Download URL	drgn-0.0.25-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl
Size	4.5 MB
Tags	CPython 3.10 Linux glibc 2.17+ x86-64
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BLAKE2b-256 checksum How to use checksums	`ce5f289c5cd4bedbcf235f207c00a6c878c5499fa475984fc24539eb387bcaa1`
Upload date	Dec 1, 2023
Uploaded using Trusted Publishing? What is trusted publishing?	No
Uploaded via	`twine/4.0.1 CPython/3.12.0`

Release files / drgn-0.0.25-cp39-cp39-manylinux_2_17_x86_64.manylinux2014_x86_64.whl

Download URL	drgn-0.0.25-cp39-cp39-manylinux_2_17_x86_64.manylinux2014_x86_64.whl
Size	4.5 MB
Tags	CPython 3.9 Linux glibc 2.17+ x86-64
SHA-256 checksum How to use checksums	`504fb330f755ce20dd0fd5fa48a67af743c80491db7c5e4a773f07d7bc814054`
BLAKE2b-256 checksum How to use checksums	`4b3775ded6080ac93b0a0d7c10964194cb230fa0f2779878fc435d11c3a88469`
Upload date	Dec 1, 2023
Uploaded using Trusted Publishing? What is trusted publishing?	No
Uploaded via	`twine/4.0.1 CPython/3.12.0`

Release files / drgn-0.0.25-cp38-cp38-manylinux_2_17_x86_64.manylinux2014_x86_64.whl

Download URL	drgn-0.0.25-cp38-cp38-manylinux_2_17_x86_64.manylinux2014_x86_64.whl
Size	4.5 MB
Tags	CPython 3.8 Linux glibc 2.17+ x86-64
SHA-256 checksum How to use checksums	`cd36945f9d83fc1c42c98ba660ecf20f6e20ab9d04ff219d18e78e75b4f1e28f`
BLAKE2b-256 checksum How to use checksums	`b8aa7265d1dd54c84597e74cd82309293348910bc16d310493d4785b552e9d38`
Upload date	Dec 1, 2023
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Uploaded via	`twine/4.0.1 CPython/3.12.0`

Release files / drgn-0.0.25-cp37-cp37m-manylinux_2_17_x86_64.manylinux2014_x86_64.whl

Download URL	drgn-0.0.25-cp37-cp37m-manylinux_2_17_x86_64.manylinux2014_x86_64.whl
Size	4.5 MB
Tags	CPython 3.7 CPython 3.7 pymalloc Linux glibc 2.17+ x86-64
SHA-256 checksum How to use checksums	`aa6f8e5fc9d2171b24314bbd9b96338b18264e146471a8eb608a3f1ee436b900`
BLAKE2b-256 checksum How to use checksums	`a47789bffad06dcf7d9cce7b9a6999b21e4576f9f62d3c03853fa8e332d9117c`
Upload date	Dec 1, 2023
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Uploaded via	`twine/4.0.1 CPython/3.12.0`

Release files / drgn-0.0.25-cp36-cp36m-manylinux_2_17_x86_64.manylinux2014_x86_64.whl

Download URL	drgn-0.0.25-cp36-cp36m-manylinux_2_17_x86_64.manylinux2014_x86_64.whl
Size	4.5 MB
Tags	CPython 3.6 CPython 3.6 pymalloc Linux glibc 2.17+ x86-64
SHA-256 checksum How to use checksums	`4ad9d7a1a16edc08a7e8d95237f5c7ad46cca5335ab8e3a619efefab7b9652bd`
BLAKE2b-256 checksum How to use checksums	`55557b215e6412e5ea92de971b01c8c468658e425205a011dd7df5729f07de42`
Upload date	Dec 1, 2023
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Uploaded via	`twine/4.0.1 CPython/3.12.0`