Please license remaining GPL-2.0-only files as 2-or-later (or LGPL?)

[zeha]

Hi,

it appears the strbuf code is licensed under GPL-2.0-only (libmultipath/strbuf.c, libmultipath/strbuf.h, tests/strbuf.c).
From a quick grep, those files seem to be the last (relevant) GPL-2.0-only files.

Given multipathd is intended to be linked against readline (which is GPL3+), I would expect that the strbuf files are supposed to be under a compatible license. Maybe they are all authored by SUSE LLC and @mwilck can quickly improve this situation?

Thanks, Chris

[zeha]

Debian bug ref https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=979095

[mwilck]

Yes, I can change the strbuf license. But as pointed out in the Debian bug, these are not the only GPL-2.0 files. There are some more:

1. libmultipath/prioritizers/ontap.c
2. libmultipath/prioritizers/datacore.c
3. libmultipath/uevent.c
4. libmultipath/sysfs.c
5. libmultipath/list.h

1, 2 are only needed for legacy hardware. 3.-5. are important, though. 3. and 4. were once copied from the udev sources. 5. was copied from the Linux kernel.

We can't easily relicense any of these files. If this means we can't use libreadline, then we must probably just drop it.

[mwilck]

There are also GPL-2.0 licensed files in kpartx. But that doesn't link to libreadline.

[mwilck]

I've posted a patch "replace libreadline by libedit" to dm-devel.

[JanZerebecki]

Perhaps the people who contributed to those files are willing to grant another license.

[zeha]

1, 2 are only needed for legacy hardware. 3.-5. are important, though. 3. and 4. were once copied from the udev sources. 5. was copied from the Linux kernel.

Right, I grepped for SPDX-License-Identifier given this is used in (apparently just some) files. Thanks!

[hreinecke]

It should be possible to get in touch with Kay Sievers to change 3-5; I'll check what I can do.

[hreinecke]

I have feedback from Kay Sievers, and he's fine with changing the license of any code attributed to him.
Exact quote (in german, I'm afraid):

Von meiner Seite aus, den Teil den ich geschrieben habe, das kannste
alles gern aendern in jede beliebige GPL-Lizenz die fuer deine Zwecke
besser passt.

[mwilck]

@zeha, I'd like to understand the concern better. IIUC, it is questionable whether the act of linking alone makes multipathd a "derived work" of libreadline, which would be the legal argument to request releasing multipathd under a GPL-3.0 compatible license.

The readline/history functionality only matters when multipathd is used as interactive command line client. This is a small and rather unimportant part of multipath-tools' functionality. In fact, I believe it wouldn't be hard to move the client functionality into a separate binary which wouldn't link to libmultipath any more and thus could be released under GPL 3.0, avoiding the GPL incompatibility concern.

Can you elaborate?

[JanZerebecki]

unimportant part

AFAIK, that is not the bar for derived work. It would need to be so unimportant that it is below the level for which copyright is granted (even the choice of case of variables is AFAIK copyrightable). And that would need to be at the time when it was potentially derived. Later rewriting on top of a replacement is not a defense for an earlier derivation.

It is difficult to argue the details of derived work. In this case so much easier to fix the license because you already have permission.

I suspect you do not like the GPL, that is OK, don't use it then. If you want to get around the intention of the GPL I will certainly not help you.

[hreinecke]

Please don't make assumptions. The sheer fact that we're discussing these issues shows that we care.
We try to be GPL compliant, but we cannot change history.
As to changing the license: whom are we required to contact?
Is is sufficient to contact the copyright owner as specified in the source code?
Or does each and every contributor to that file need to be contacted?
Do you know?

[mwilck]

AFAIK, that is not the bar for derived work. It would need to be so unimportant that it is below the level for which copyright is granted (even the choice of case of variables is AFAIK copyrightable).

That's the PoV of the FSF, right? I don't think it's universally accepted.

And that would need to be at the time when it was potentially derived. Later rewriting on top of a replacement is not a defense for an earlier derivation.

At the time multipath-tools started using libreadline, the latter was under GPL v2.0 or later, and there was no license conflict. The conflict arose only because the FSF chose to create a successor license that was incompatible with its predecessor, and because readline chose to switch to this new license. Our mistake — as multipath-tools maintainers — was not to realize this.

It is difficult to argue the details of derived work.

We agree on this point. It's also known to have different meanings in different jurisdictions. I am just saying that your very broad interpretation isn't everyone's, even if it might actually have been the intention of the GPL's author. I tend to prefer a more common-sense interpretation. multipath-tools has ~75000 lines of C code, of which 10 (including comments and #include statements) reference libreadline. It just makes no sense to me to speak about a "derived work" here.

In this case so much easier to fix the license because you already have permission.

This is not true. We have permission from Kay thanks to Hannes' inquiry, and I'm assuming that the current active contributors would also grant permission. But we'd need permissions from quite a few more people to be clean.

I suspect you do not like the GPL, that is OK, don't use it then. If you want to get around the intention of the GPL I will certainly not help you.

If you look at the original issue, you can see that the problem was that I chose GPL-2.0-only as license for some of my contributions. Which was a mistake, I should have used GPL-2.0-or-later; but I was unaware of the libreadline problem. Also, you certainly realize that even if we wanted (we don't), we can't stop using the GPL. Almost the entire code base of multipath-tools is under some variant of the (L)GPL.

As Hannes already, said, we are actively working on cleaning up this situation.