Compliance engineering as a topic covers those activities that make it possible to ship a (consumer electronics) product that complies with the license(s) of the software contained in that product. That includes things like: figuring out what software actually is in the product (you'd be surprised how often vendors don't even know); ensuring that you know what configurations and versions were chosen to put in the product; finding out what the licenses on those versions of the software are; finding out out what the obligations under those licenses are; and finally actually doing what those obligations demand. Hence, comply.
Comply or explain (to one of the organizations that look into enforcing software license obligations, like the BSA or gpl-violations.org).
One popular license for software that tends to end up in consumer electronics products is the GPL. Either version 2 or version 3. It has some specific obligations that make compliance both important and sensitive. Those are the clauses requiring the complete corresponding source code, which means you need to know what the code is and how to provide it. It also means that for every binary release you need to provide the sources that can be used to create exactly that binary release. Not every company does that consistently.
Heck, I'll name names: Conceptronic, a Dutch consumer electronics company, tries hard to comply. It delivers source code for the firmware shipped with the original release of devices, and it sometimes updates the available source tarballs. But not always. Dennis, the guy responsible, knows this is a problem. He tries, but time pressure and the upstream don't always make it possible to do the right thing.
So there's a company technically in the wrong where I'm willing to believe that they could be in the right if there was a little less effort involved, or a little better support in the compliance engineering process.
Enter, once more, Armijn and Shane, in their business guises of Loohuis Consulting and Opendawn Consulting. They work, shall we say, both sides of the fence: both in helping people improve their compliance processes and in tracking down violators later. For both sides, knowing which sources should have been supplied with a given binary release is of paramount importance.
So Shane and Armijn -- supported by the Linux Foundation and Stichting NLnet -- have produced a tool that helps in identifying what software has gone into a binary firmware image. It's still in its infancy, but it can usefully detect Linux kernel versions, Busybox versions and configurations. That means it can be used -- for products containing those pieces of software -- to answer questions like "what sources and configuration files and scripts should be delivered with this product?" And that's important because of the requirement in the GPL to provide (when necessary as defined by the other license obligations) the complete corresponding source code. Not just a bunch of tarballs and a "figure it out" notice; not just the upstream code, but whatever patches went into the device as well; and preferably not a whole bunch of extraneous cruft, either.
The tool makes it easier to do compliance checking from the outside, and easier and cheaper (as in Free beer) to do basic checking on the inside. It's no replacement for a dedicated compliance engineer, but it does help a lot in answering questions about "what's in here?" before firmware goes out the door.
I should add that the tool understands some common firmware packaging styles, so it will find and unpack and check things in a squashfs image. Upcoming features will add more filesystems, like concatenated squashfs filesystems, which will save a lot of time compared to running od -c, grepping for magic numbers, dd-ing things apart and then loopback mounting parts individually -- that will become automatic.
You can find the tool (which is Free Software under the Apache license) at BinaryAnalysis.org. BA to the rescue. Man, I love it when a plan comes together.