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Comment by kleiba | Hacker News Reader

Here's a question for my fellow HNers.

In the article linked from his tweet, Carmack describes how he ported Wolfenstein3D to the iPhone. He apparently didn't start off with their own original code base, but used the open source project "Wolf3D Redux" (http://wolf3dredux.sourceforge.net) as a starting point. This was possible because id open sourced their original game, and "Wolf3D Redux" is distributed under the GNU GPL v2.

Carmack also states: "I think the App Store is an extremely important model for the software business."

Therefore my question: is it possible to publish GPL'd games in the App Store? I seem to remember that this was not possible, since ToS of the app store impose further constraints which is forbidden under the terms of the GPL.

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No version of GPL is compatible with the App Store, because Apple requires that you take away rights from users that GPL protects (users must accept 5-install DRM, Apple ID with geographic restrictions, etc.), which is forbidden in section 6 of GPL.

http://www.fsf.org/blogs/licensing/more-about-the-app-store-...

I have verified that first hand by asking Apple to remove derivative of my GPL-licensed software that they were pirating and Apple complied.

In case of Wolf3D my guess is that ID Software got commercial license from the author(s) of that software (copyright holder of GPL software can choose to also license it under another license).

It's possible, though it depends on the wishes of the original authors.

Stockfish Chess [1] is the one GPL v3 licensed app that I know of which has been available for... quite some time, now. I've seen several other Chess apps build on that engine, which go as far back as when I was just starting iOS development.

Now, VLC was the one case where one volunteer for the project invoked the GPL to get Apple to take an iOS port of the app off the store [2]. Based on that situation, it seems that if the original authors of a GPL licensed codebase want to pursue a claim against an app that uses that code, they can, and Apple will take it seriously.

I don't believe that situation has changed.

EDIT: For your own sake, it's probably best if you approach the original author to see if they can make an exemption, in writing, for the DRM situation. IANAL, but that seems like it would be the cleanest way to go about handling GPL licensed code without issue.

[1] - http://stockfishchess.org

[2] - http://www.tuaw.com/2011/01/08/vlc-app-removed-from-app-stor...

Remember, you'll need to contact all the authors and they all have to consent to (essentially) relicense their code. Any open source project that accepts patches may have dozens of actual authors. You can't just ask the project maintainer/chief contributor.

Ideally, a well-organized project would have a copyright assignment process to resolve those sorts of issues.

However, as far as I know you're right. If there's no clear authority as to who retains ownership and licensing rights to the code, and the contributions made to it, it's going to get messy.

> Ideally, a well-organized project would have a copyright assignment process to resolve those sorts of issues.

That only works in the US, there are various jurisdictions where it is impossible to allow third parties to relicense one’s IP in any way they want.

Interesting. Do you have details on which jurisdictions do not allow this, and why?

I admit that I'm not familiar with international copyright law. I do know that several GNU projects, and other high profile open source projects, have a policy in place wherein contributors have to agree to a copyright assignment agreement before they can contribute their modifications.

If that's not possible in some regions, they clearly still have some means of continuing to uphold their own IP. I suspect it's not as harsh as completely avoiding contributions from some regions of the world. Unless I'm mistaken.

It is not possible to assign copyright in German IP law, it is non-transferable and tied to the creator of the work or his heirs. There are some ways around this for purely software projects, e.g. the FSF Europe has a license agreement, which covers pretty much everything and should be enough for nearly all uses.

However, similar agreements (i.e. an artist allowing a record company to use his song however they wanted) signed in the 70s have been found to not extend to ‘digital’ uses, of e.g. music, by German courts as this use case did not exist yet at the time the license was granted.

I’m really saying that this is an annoyingly complicated matter and best avoided by not requiring relicensing – and I’m not a lawyer, of course (and also too lazy to find references now).

And, naturally, there is the issue whether you trust the FSF enough to do the right thing.

> Ideally, a well-organized project would have a copyright assignment process to resolve those sorts of issues.

A lot of projects, notably including Linux, intentionally avoid copyright assignment to make it impossible for anyone to relicense the codebase. Making sure that there are thousands of copyright holders from hundreds of jurisdictions, many of who are not easily reachable or even knowable, all bound by common license terms protects the project from situations where some project participants would do something not agreed by the rest, either willingly or because they were forced to (eg. through bankruptcy).

That's a good observation, some inefficiencies are quite intentional. I didn't even know that about Linux until just the other night, when I was looking for non-GNU GPL projects that didn't require this process.

LWN.net has covered both sides of this subject quite well, in recent months, with the tedious process of relicensing VLC [1] and the GnuTLS copyright assignment controversy [2].

The politics of OSS make for some excellent reading.

[1] - https://lwn.net/Articles/525718/

[2] - https://lwn.net/Articles/529522/

Since it's licensed under the GPL, I should get the source code when I buy the game, right (as a link to a github repo or whatever)?

It needn't be bundled with it, but must be available upon request, for a "charge no more than your cost of physically performing source distribution [...] on a medium customarily used for software interchange" (that's article 3 of the GPL2. The GPL3 is a bit more detailed, but similar in spirit)

I think it's only GPLv3 which forbids distribution on locked-down devices. I would guess that GPLv2 is compatible with the iPhone.

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