Ask HN: Have licenses ever stopped you from combining two FOSS programs?

https://news.ycombinator.com/item?id=34776347

by josephcsible • 3 years ago

23 27 3 years ago

news.ycombinator.com

Not all FOSS licenses are compatible with each other. The best-known example is that the CDDL and GPL are incompatible, which is why the mainline Linux kernel doesn't have ZFS. I'm curious how common this actually is, though. Aside from the ZFS-on-Linux case, has anyone else wanted to combine two FOSS programs but been unable to because of a license incompatibility?

Xylakant• 3 years ago

For a long time, Debian/Ubuntu shipped unusable ruby packages due to the ruby/OpenSSL licenses being incompatible.

brianm• 3 years ago

Yes, but it mainly has come up when combining libraries and releasing something else as OSS. For example, the ASF has a good examination of the effect of combinations with the AL2: https://www.apache.org/legal/resolved.html

kazinator3• 3 years ago

I put code under a BSD license, so on many occasions I've been prevented from using GPLed code. BSD and GPL are not incompatible. BSD and GPL pieces can be combined into a single program, while retaining their individual licenses; the problem is that the combination has to be redistributed under the GPL. Compatibility is not the only question, but what kind of compatibility: what must the master license be if the combination is made.

Cygwin changing to the LGPL back in 2016 enabled me to distribute BSD code with Cygwin DLL's without having to GPL the code. When I learned from the Cygwin mailing list about this change, I immediately set to work to create a fork of the Cygwin DLL which provides more native-like behaviors, to be used as run-time library for programs. Had they not announced a licensing change, I'd not have done anything of the sort.

torstenvl8• 3 years ago

Have you considered releasing your code under both BSD and GPL?

kazinator3• 3 years ago

No; it makes no (logical) sense.

satvikpendem• 3 years ago

If I'm not modifying the source and just using the built application, then I have nothing to worry about regarding mixing programs.

josephcsible6• 3 years ago

It doesn't matter whether or not you modify the source. The thing that makes you not have to worry about licenses is if you don't distribute the result.

torstenvl8• 3 years ago

I have serious doubts that this is true, because (a) the text of the GPL itself is insufficiently clear on this IMHO; and (b) dynamic linking is literally just a declaration of an API you want to use and where the dynamic linker should look for that API provider, but APIs are, at least in some cases, fair use. See Google LLC v. Oracle America, Inc., 593 U.S. ___ (2021) available at https://supreme.justia.com/cases/federal/us/593/18-956/

You can easily make a binary that will use GNU libreadline, if it exists, without ever installing GPL software on your machine, let alone using it in compiling your distributable binary.

    freebsd% ls
    readlineshim.c readlineshim.h test.c
    freebsd% cat test.c
    #include <stdio.h>
    #include "readlineshim.h"
    
    int main(void) {
        char *name;
        name = readline("What's your name? ");
        if (name) printf("Hello, %s!\n", name);
        return 0;
    }
    freebsd% cat readlineshim.h
    char *readline(const char *p);
    freebsd% cat readlineshim.c
    char *readline(const char *p) {
        return ((void *)0);
    }
    freebsd% cc -c -fPIC readlineshim.c -o readlineshim.o
    freebsd% cc -shared readlineshim.o -o libreadline.so
    freebsd% cc test.c -o test -Wl,-rpath-link=. -L. -lreadline
    freebsd% ./test
    ld-elf.so.1: Shared object "libreadline.so" not found, required by "test"

At this point, test.c has been compiled into a distributable binary without linking any GNU software, but it requires GNU software to run...

    freebsd% sudo pkg install -qy readline
    freebsd% ./test                       
    What's your name? Lee
    Hello, Lee!
    freebsd%

Since GNU software is only required to run the program, then either (a) FSF's claim to cover dynamically-linked programs is false, or (b) the GPL isn't a free software license because it places restrictions on use.

rolenthedeep• 3 years ago

A very long time ago I took over a FOSS project under GPL. It had pretty good support for plugins, a lot of demand for plugins, and exactly zero third-party plugins that were even remotely maintained.

I don't think we ever got many direct complaints about GPL, but our main assumption was that copy left contamination was pushing developers away. We wanted more open licensing to encourage wider adoption, so we started a replacement project under MIT license, I believe.

Once the replacement project was in a good state, suddenly plugin developers started crawling out of the woodwork.

My estimation is that about 30% of our trouble was due to licensing concerns, and the rest was down to the original project being in a very, very bad way. It was very old, had been abandoned by six developers, and about 70% of the code was unused and unusable.

The new project had bells and whistles and was more attractive, but I think the open license definitely helped.

You probably could have built a plugin without needing to use the GPL, but it would have been a lot more difficult. That whole project was a disaster, and I never once regretted letting it finally die.

lloydatkinson2• 3 years ago

What project is this?

lloydatkinson2• 3 years ago

Guess we will never know. How OP expects anyone to maintain said project when being secretive about it, I've no idea.

psacawa• 3 years ago

It happens all the time for software that is copyleft-licensed in projects that are unwilling to also adopt a copyleft license. For example, it blocks linking the node interpreter to libreadline [0]. On the other hand, cpython is also permissively licensed, yet it does link to the same library, so who knows what the legality of linking against a GPL lib really is.

[0] https://github.com/nodejs/node/issues/5608

josephcsible6• 3 years ago

This isn't quite the kind of conflict I meant, since the licenses are compatible and the maintainer just doesn't want to do it.

rurban• 3 years ago

Still struggling from this famous fallout:

https://librearts.org/2012/01/whats-up-with-dwg-adoption-in-...

I'm the maintainer, the FSF owns the code, and I'm very fine that it's GPLv3. Others not so, but we don't care. GPLv3 is the only possibility.

nubinetwork• 3 years ago

In the Linux space, it doesn't really bother me... Packages in distros use all kinds of licenses, and as long as you're up front with what you're using and provide the source or license as required.

If "this product is made from a combination of domestic and foreign components" is good enough for physical goods, then it should be good enough for software.

But IANAL. :)

Ask HN: Have licenses ever stopped you from combining two FOSS programs?

Related Stories