
What is copyleft? - gexos
https://opensource.com/resources/what-is-copyleft
======
chungy
> I prefer to think of the distinction in this way: permissive licenses
> provide the maximum freedom for downstream developers (including the ability
> to use the open source code in a closed source project), whereas copyleft
> licenses provide the maximum freedom for downstream users.

This is a common analogy but it never sits well with me. Really, the
permissive licenses allow the code to show up in places that copyleft licenses
would not allow it. There are a ton of open source projects used in Microsoft
Windows or iOS thanks to their permissive licensing -- and neither Microsoft
nor Apple are legally obliged to give anything back.

Copyleft licenses prevent the software from being forked into a proprietary
program and the changes hidden from the user. To take a random example, if
Microsoft took GNU gzip and included it with Windows, and then extended it
with new features, Microsoft would be obliged to provide the source code to
those changes. If they took OpenBSD's implementation instead, they wouldn't be
obliged in the same way (though they still _could_).

Remaining entirely in the open source world, these licenses concern
redistribution of software. A user on OpenBSD does not feel they have any less
freedom than a user on GNU/Linux. They don't have any less freedom, after all.
Users on both systems retain the full gamut of freedom. To run for any
purpose, to study the source code, to modify the source code, to redistribute
the software verbatim or modified. The difference shows up when it comes to
this: Do you want to be an asshole? OpenBSD permits the option -- you can
distribute a fork without the source code. You cannot do that with a GPL-
licensed system.

The FSF and other GPL advocates usually ride on the premise that opening up
the possibility for downstreams to be assholes is bad, with few exceptions. I
do respect their opinions, but I feel like the history of open source (and the
*BSDs, even) show that such assholes don't get very far. They simply cannot
compete with the pace of open and transparent development and die off on their
own. Frankly, being an asshole is an irrational and unprofitable (socially and
commercially) move, and trying to nanny the behavior away isn't all that
necessary.

~~~
Flimm
You're comparing users of OpenBSD to users of GNU/Linux, but why not compare
both of them to users of Windows and OS X? Why is FLOSS software pitted
against each other, instead of FLOSS software against proprietary and closed
source software?

~~~
chungy
I'm sorry, I didn't mean to pit them against each other, just pointing out
that users of either system enjoy the same freedoms regardless of the license
choices. :-)

Windows, OS X, iOS, and all other proprietary systems do, in fact, restrict
users and objectively have fewer freedoms than free ones.

~~~
AimHere
And there is, or was, BSD code in both Windows and OSX, some of which was
locked off in proprietary parts.

OSX also contains some GPLed code, all of which is available to the user under
righteous free software terms (as is at least some of their permissive-
licensed code).

The problem that Stallman and the FSF complain about isn't the relative
freedom of the users of OpenBSD and GNU/Linux, but what happens to the
freedoms of users who are further downstream.

------
bkuhn
Those who wish to learn more about copyleft after reading Ben's article may
also want to look at the copyleft guide
[https://copyleft.org/guide](https://copyleft.org/guide) for more information.

Ben is a contributor to the copyleft guide, so we'll likely merge in his
article into the Guide.

------
anjbe
Discussions of copyleft versus permissive licensing always seem to cover the
same “freedom for users versus freedom for developers” clichés and the same
tired slavery metaphors.

My dislike of copyleft is emphatically not because I want to enable
proprietary software. I hate proprietary software, and don’t use it on my
machines.

No, my biggest complaint about copyleft has always been that it prevents
_other free software_ from being able to use it. Copyleft licenses actively
lead to incompatibility.

Remember when LibreDWG, an AutoCAD file parser, couldn’t be used in various
free software CAD projects, because LibreDWG is GPLv3+ and FreeCAD, etc were
GPLv2 only? [http://libregraphicsworld.org/blog/entry/libredwg-drama-
the-...](http://libregraphicsworld.org/blog/entry/libredwg-drama-the-end-or-
the-new-beginning)

If FreeCAD had been under a permissive license, it would have been able to
link against LibreDWG. If LibreDWG had been under a permissive license,
FreeCAD would have been able to link against it. If they were _both_ under a
permissive license, they would have been able to be linked together _and_
share code directly!

How about when NYC released open building and address data? A laudable move,
one that helped several open source projects, the largest probably being
OpenStreetMap. OpenStreetMap is under a copyleft license, and though they
benefit from NYC’s data, due to the licensing NYC can’t make use of
OpenStreetMap’s improvements without a convoluted parallel construction
scheme:
[https://www.openstreetmap.org/user/lxbarth/diary/23588](https://www.openstreetmap.org/user/lxbarth/diary/23588)

A common response is that the onus is on NYC to release their data under a
copyleft license so they can benefit. But there are often significant (even
legislative!) barriers to doing that, especially in the United States where
government entities are often required to release data to the public domain.
How about changing that legislation? Well, if you had initiated such a
legislative reform just a few years ago OSM would have been under the Creative
Commons BY-SA—which is incompatible with OSM’s current license, the ODbL.

Remember how much grief has resulted from the unclear (or perhaps too clear)
licensing status of ZFS on Linux?

Releasing software and data under the freest, most permissive license possible
prevents such a thing from ever happening. I would rather allow a hundred
Chinese featurephone vendors to lock down their crappy derivatives of my code
than use my copyright to prevent a free software project from using my code in
good faith.

~~~
aylons
> But there are often significant (even legislative!) barriers to doing that,
> especially in the United States where government entities are often required
> to release data to the public domain. How about changing that legislation?

If it is public domain, it may be incorporated at software licensed in any
form, even whole proprietary.

Also, public data must be public domain, but software used by government
doesn't.

~~~
michaelt
I believe the poster's point was:

If the government is required to release the data as public domain; then it's
integrated into OpenStreetMap which is copyleft; then a correction is made to
OpenStreetMap; the correction can't be merged back into the public domain
data.

Thus the copyleft project, in their attempts to stop people freeloading on
their work without contributing back, have freeloaded on someone else's work
without contributing back.

~~~
brudgers
[IANAL]

One of the features of GPL is there is low administrative overhead in regard
to legal matters when accepting contributions. The legal simplicity comes out
of copyleft fully utilizing strong copyright and under GPL authors do not give
up any rights.

On the other hand, placing a work in the public domain requires the author to
give up their rights under copyright. Public domain is not a license. It is a
legal sibling, not a child, of copyright. The result is that public domain
works require legal administrative overhead in order to accept
contributions...for example, an organization may find it necessary to create
and maintain documentation regarding how and when each outside contributor
placed their work in the public domain. Some open source licenses, such as
Eclipse, also require similar record keeping.

That's not to say that GPL's reliance on the same classes of strong copyright
law that the entertainment industries see as useful is necessarily
unproblematic.

------
dhimes
Can you make money writing and selling copyleft-licensed software? The
licenses always appeared to me to make that difficult. I write one, sell it,
and the purchaser can now give it away for free. But I probably just don't
understand it.

~~~
cyphar
The same argument is true for _any_ free software. If you sell free software,
then the purchaser necessarily must have the freedom to distribute said
software. So copyleft hasn't changed anything in that regard.

And there are several companies that sell free (and even copylefted) software.
SUSE and RedHat are the prime examples -- the way it works is that you sell
support licenses. So if they want to get L3 support for a bug they found (or
want you to work on a new feature) they have to pay you. It's a fairly simple
model (though more complicated than the standard proprietary model of "my
binaries are holy and you must pay me for them" \-- which I always found to
make no sense because software isn't a real thing).

~~~
dhimes
I was really asking a question, but I think I understand your answer. I can
see where there is a business case for it, but also the other.

As an example from another field, my architect drew up plans for my house. I'm
only allowed to use those plans for _that_ house. I can't build another house
just like it, and I can't sell the plans to somebody else.

His expertise and hard work went into making the plans. It's no more "real"
than a print-out of a program. Yet it would be very hard for him to make a
living if other architects could just take his plans and use them.

And the idea of selling giving the program away for free but charging to fix
the errors may not be the best for all cases.

I can see the case for copyleft, but I don't think it's the _only_ case. (Not
that you said it was- in fact, I've heard some people say something like that
but not too many.)

~~~
squeaky-clean
> His expertise and hard work went into making the plans. It's no more "real"
> than a print-out of a program. Yet it would be very hard for him to make a
> living if other architects could just take his plans and use them.

That analogy doesn't totally work with software though. There aren't (for-
profit) companies that focus solely on architecture without building software.

It's more like if the architect also owned a construction firm and posted the
plans for free on their website with a notice like "ConstructionCo provides
these plans free of charge and AS-IS for use when building your own home. If
you are looking for a team to build one of these plans, please consider
contacting ConstructionCo as we have years of experience with these specific
housing plans, and can offer you a warranty and home-insurance as part of a
package. If you like these plans, but want modifications to the design,
ConstructionCo can gladly accommodate you for a price."

~~~
dhimes
Excellent. But the problem here is you don't have the 'construct the home'
step in using software. You can (let's say) take the specs and 3d-print it.
You only need to hire the firm for changes and bug-fixes, and, even then, if
you wanted something unique you're out of luck because you have to give away
your uniqueness.

Maybe a better analogy would be writing songs. If you weren't allowed to
copyright songs but only performances, then those who simply wrote songs would
be out of luck, because those who could perform them better but couldn't write
as well would simply take their work.

Or if a writer couldn't copyright her book but only her readings of it.

------
snambi
"Permissive" licenses provide highest freedom to "distributors".

"Copyleft" licenses provide highest freedom to "end-users".

"distributors" normally tend to be corporations that want to benefit from
"free" software, but OTOH deny the same freedom to their own users. In other
words, software that uses free software internally, but it itself was a
proprietary with stringent license terms.

------
dec0dedab0de
I think the best explanation of the differences between Free Software, Open
Source, and Copy Left is the first 30 minutes of Revolution OS.

This part for copyleft, does anyone really find this difficult to understand?

[https://www.youtube.com/watch?v=k84FMc1GF8M&t=17m13s](https://www.youtube.com/watch?v=k84FMc1GF8M&t=17m13s)

