Petter Reinholdtsen

Making packages for Debian requires quite a lot of attention to details. And one of the details is the content of the debian/copyright file, which should list all relevant licenses used by the code in the package in question, preferably in machine readable DEP5 format.

For large packages with lots of contributors it is hard to write and update this file manually, and if you get some detail wrong, the package is normally rejected by the ftpmasters. So getting it right the first time around get the package into Debian faster, and save both you and the ftpmasters some work.. Today, while trying to figure out what was wrong with the zfsonlinux copyright file, I decided to spend some time on figuring out the options for doing this job automatically, or at least semi-automatically.

Lucikly, there are at least two tools available for generating the file based on the code in the source package, debmake and cme. I'm not sure which one of them came first, but both seem to be able to create a sensible draft file. As far as I can tell, none of them can be trusted to get the result just right, so the content need to be polished a bit before the file is OK to upload. I found the debmake option in a blog posts from 2014.

To generate using debmake, use the -cc option:

debmake -cc > debian/copyright

Note there are some problems with python and non-ASCII names, so this might not be the best option.

The cme option is based on a config parsing library, and I found this approach in a blog post from 2015. To generate using cme, use the 'update dpkg-copyright' option:

cme update dpkg-copyright

This will create or update debian/copyright. The cme tool seem to handle UTF-8 names better than debmake.

When the copyright file is created, I would also like some help to check if the file is correct. For this I found two good options, debmake -k and license-reconcile. The former seem to focus on license types and file matching, and is able to detect ineffective blocks in the copyright file. The latter reports missing copyright holders and years, but was confused by inconsistent license names (like CDDL vs. CDDL-1.0). I suspect it is good to use both and fix all issues reported by them before uploading. But I do not know if the tools and the ftpmasters agree on what is important to fix in a copyright file, so the package might still be rejected.

The devscripts tool licensecheck deserve mentioning. It will read through the source and try to find all copyright statements. It is not comparing the result to the content of debian/copyright, but can be useful when verifying the content of the copyright file.

Are you aware of better tools in Debian to create and update debian/copyright file. Please let me know, or blog about it on planet.debian.org.

As usual, if you use Bitcoin and want to show your support of my activities, please send Bitcoin donations to my address 15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

Update 2016-02-20: I got a tip from Mike Gabriel on how to use licensecheck and cdbs to create a draft copyright file

licensecheck --copyright -r `find * -type f` | \
  /usr/lib/cdbs/licensecheck2dep5 > debian/copyright.auto

He mentioned that he normally check the generated file into the version control system to make it easier to discover license and copyright changes in the upstream source. I will try to do the same with my packages in the future.

Update 2016-02-21: The cme author recommended against using -quiet for new users, so I removed it from the proposed command line.

The appstream system is taking shape in Debian, and one provided feature is a very convenient way to tell you which package to install to make a given firmware file available when the kernel is looking for it. This can be done using apt-file too, but that is for someone else to blog about. :)

Here is a small recipe to find the package with a given firmware file, in this example I am looking for ctfw-3.2.3.0.bin, randomly picked from the set of firmware announced using appstream in Debian unstable. In general you would be looking for the firmware requested by the kernel during kernel module loading. To find the package providing the example file, do like this:

% apt install appstream
[...]
% apt update
[...]
% appstreamcli what-provides firmware:runtime ctfw-3.2.3.0.bin | \
  awk '/Package:/ {print $2}'
firmware-qlogic
%

See the appstream wiki page to learn how to embed the package metadata in a way appstream can use.

This same approach can be used to find any package supporting a given MIME type. This is very useful when you get a file you do not know how to handle. First find the mime type using file --mime-type, and next look up the package providing support for it. Lets say you got an SVG file. Its MIME type is image/svg+xml, and you can find all packages handling this type like this:

% apt install appstream
[...]
% apt update
[...]
% appstreamcli what-provides mimetype image/svg+xml | \
  awk '/Package:/ {print $2}'
bkchem
phototonic
inkscape
shutter
tetzle
geeqie
xia
pinta
gthumb
karbon
comix
mirage
viewnior
postr
ristretto
kolourpaint4
eog
eom
gimagereader
midori
%

I believe the MIME types are fetched from the desktop file for packages providing appstream metadata.