What is Copyleft?

[John Cowan]

Ryan S. Dancey wrote:

> If I understand the internals of the situation correctly (which I may not),
> a program that binds to a DLL at runtime does so through the mediation of
> the OS.  Data is packaged, handed to the OS, the OS moves it from the
> process making the call to the target process, where the data is unpacked
> and loaded into the target's address space.  There's never a time where the
> free software is even in the same address space as the (potentially)
> non-free library code.

No, DLLs are in the same address space as the main program.  They are
ordinary code that instead of being mapped at link time, is mapped at
the beginning of run time.  Calls to a routine in a DLL are essentially
ordinary subroutine calls indirected through a table of pointers.


> Is a web page with external URLs a "derivative work" of the base page and
> all the pages the links (and those page's links, ad nauseum) refer to?

No.  A book that refers to another book by name (e.g. in the
bibliography) is not a derivative of the other book.  However, if a
web page incorporates graphics from another site, it is arguably a
derivative work.  If it frames another web page, it is also arguably
a derivative work.

The definition of "derivative work" is statutory, and no court has
ever put it to the test in these situations.

> If I use a GPL'd program to output a CSV data file, and import that into a
> database, is a derivative work created that combines my code and the
> database?

Not unless the program outputs some part of itself, as bison does.
Bison-generated parsers used to be under the GPL until this was
changed recently.

-- 
There is / one art             || John Cowan <jcowan at reutershealth.com>
no more / no less              || http://www.reutershealth.com
to do / all things             || http://www.ccil.org/~cowan
with art- / lessness           \\ -- Piet Hein