Hi,
On 06/23/2016 04:26 PM, David Sterba wrote:
On Sat, Jun 18, 2016 at 12:01:53AM +0200, Hans van Kranenburg wrote:
proof-of-concept level scripts to be able to debug my btrfs file
systems, the inevitable happened:
https://github.com/knorrie/python-btrfs/
Currently, the primary goal of this module is to be able to inspect the
internals of an existing filesystem for educational purposes.
Looks great, I like.
Thanks, much appreciated!
Python is better language for prototyping various
things, also more convenient to write one-shot scripts to do specific
rescue tasks.
The python module acts as a wrapper around the low level kernel calls
and btrfs data structures, presenting them as python objects with
interesting attributes and references to other objects.
I guess it could be extended to read the filesystem objects directly
from the image, so it's not only built around the search ioctl.
Why?!
* Because it's fun!
Best reason ever!
Moo!
* Because I get sick of using horrible ducttape regex solutions to
programmatically parse human readable output of external tools to
implement monitoring tools~~!11one.
This is actually the main reason I started it. Or was it being able to
see where balance got the usage information from...
* Because I might to be able to help other people that also want to
learn the internals of btrfs.
* Much more...
How?
* It's a python library, so the code will have a decent level of
pythonicity. The ioctl search returns a generator, the search key is a
nice object you can just increment etc...
* This is a work in progress. I can only add support for parts of btrfs
that I understand myself first.
My question is whether it sounds like a good idea to host the python
bindings inside btrfs-progs or not.
Whoa, hold your horses!
I can imagine creating scripts to
craft images for testing or verifying results of fsck, so it would be
more convenient to keep them in one place (but using a git submodule
instead would not be a big deal).
python-btrfs is just a library. You can just clone the git somewhere,
start hacking on it and put it in your python path, or pip install or
apt-get install python-btrfs etc...
Programs that use it can be anywhere. What I have in examples/ now
should probably end up either in howto style documentation or in proper
tests for the lib (which requires keeping known-state filesystem images
to test on etc, exploding into a new level of whoa).
I'm mostly interested in the object representation of the filesystem
objects and basic API around that, so if you have other plans with
python-btrfs, we can at least share some of the code. My python-fu is
not that strong so I'd rely on you or others to maintain that if you're
interested.
Ok, I added a little TODO:
https://github.com/knorrie/python-btrfs/blob/master/TODO.md
There's a few things I want to do first at least, which are completing
to support the full set of data structures using the kernel API,
finishing to move existing code that I have lying around to use the new
lib and a bit of extra info to help interested sysadmin/programmers to
start using the library to peek around in their own filesystem a bit to
see what's going on.
I haven't looked at how the btrfs-progs treat disks directly, but would
certainly be interested in learning about that.
From what you say, I feel that you're thinking about not only looking
around in filesystems, but having ways to manipulate them?
Can you provide a more concrete example of "craft images for testing" or
related ideas about how this project could help during regular btrfs
development?
--
Hans van Kranenburg - System / Network Engineer
T +31 (0)10 2760434 | hans.van.kranenburg@xxxxxxxxxx | www.mendix.com
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