[GLLUG] LGPL and GPL - linking and distribution

Richard Houser rick at divinesymphony.net
Sun Mar 9 19:28:26 EDT 2008


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| On Sat, Mar 8, 2008 at 4:20 PM, Mike <msg at msu.edu> wrote:
|> So someone gets "libraryA.dll" off the internet.  It's under one of
|>  LGPL/GPL.  (It's source code is public, and not modified.)
|>
|>
|>  They compile "programB.exe" under a proprietary license.  (It's closed
|>  source.)  It links with "libraryA.dll" during execution.  Are there
|>  restrictions on "programB.exe"?
|
| It depends on whether libraryA.dll is licensed under the GPL or the
| LGPL. The LGPL explicitly allows this whereas the GPL does not. If
| libraryA is dual-licensed under both, it's presumed that the LGPL will
| apply. It would be silly to pick the GPL only to violate it by linking
| proprietary code against it.

It is also possible to customize the GPL by listing specific exceptions.
~ One very common exception is for linking purposes with the OpenSSL
codebase, or to allow others a choice to use a later version of the GPL
at their option.

|>  This person wants to distribute them both in "programB.msi".  What
|>  should its license be like?  (Can it read the same as the proprietary
|>  license for "programB.exe"?)

If you distribute programB.msi under the GPL, then the entire contents
is under the GPL.  The bundle could contain public-domain code, BSD
licensed, etc, that are eligible to be re-licensed under the GPL.  There
are some specific terms about this in the GPL if I recall.  You can
distribute a bundle with mixed licenses, but cannot claim the bundle
under that one license unless all the terms still hold true.

| You wouldn't license an installer file any more than you'd license a
| zip file or tarball, or CD image. The license of the software inside
| is what matters.

Actually, they both matter.  I've personally dealt with several cases
where the installer had a different license than the software it
actually installed, such that you couldn't always redistribute the
existing installer, but you could the software if you repackaged it, etc.

Basically, you need to make sure you have the appropriate permissions in
all components to do what you wish.  There are some particular sections
in the GPL family of licenses that deal with these "bundles" if I
recall.  It's been a while since I read them, however.

| The installer, again, is a container rather than a piece of
| intellectual property itself.

There's a lot of work that goes into many installers, and they can most
definitely be a form of intellectual property.  I doubt any courtroom
would rule something as simple as a zip archive layout to contain
restricted IP, but something like a GUI installer, Gentoo e-build, RPM
SPEC file, or the internally stored scripting would most certainly be
considered as such.

| I would imagine that microsoft has
| already copyrighted the installer for themselves, but that doesn't in
| any way affect the licensing or copyrights of its contents.

They can.  For example, many of the installers created by Installshield
have explicit restrictions in the license that prevent users from
extracting the files via any means other than an official, bundled
InstallShield installer.  Such a case was one of the major obstacles to
the first NeverWinter Nights Linux client (which resulted in a necessary
1.2GB resource download even though each user had the appropriate files
on CD).



Regardless of the summaries you get from others, you must abide by ALL
restrictions in each of the licenses from resources you distribute or
create derivative works from.  These licenses grant you additional
rights you would otherwise not have.  Without following them to the
letter, for instance, you would have no right to engage in distribution.

These licenses were designed to be easily read by non-lawyers, but still
hold up to legal scrutiny.  None of them are particularly complicated as
to how they pertain to end users or those involved in distribution.  I
suggest you spend the hour to familiarize yourself with the GPL, LGPL,
and at least read the summaries of some of the more popular alternatives
like the MIT, Apache, and BSD licenses.
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