Linking restrictions and shared libraries

Rod Dixon, J.D., LL.M. rod at
Mon Mar 12 15:56:38 UTC 2001

Section 117
Section 117(a) of the Copyright Act, seems applicable. It limits the right
of the copyright holder with regard to computer programs, and is relevant to
the dynamic linking of shared libraries. Given the general purpose of the
GNU GPL, we can make two assumptions about its provisions: [1] it does not
restrict a right of the user that is provided for by the Copyright Act under
section 117(a)(1) since to do so would have the ironic result of
undercutting the access to works that public law provides to everyone and
[2]  to be faithful to the current distinctions between the GNU GPL and the
LGPL, care must be undertaken to distinguish that the licensor is,
generally, the author of the shared library, who permits proprietary
applications to link to the library by using the LGPL. (Quite a different
question may arise, if the facts are altered just slightly).

(a) Making of Additional Copy or Adaptation by Owner of
Copy.-Notwithstanding the provisions of section 106, it is not an
infringement for the owner of a copy of a computer program to make or
authorize the making of another copy or adaptation of that computer program

(1) that such a new copy or adaptation is created as an essential step in
the utilization of the computer program in conjunction with a machine and
that it is used in no other manner, or

(2) that such new copy or adaptation is for archival purposes only and that
all archival copies are destroyed in the event that continued possession of
the computer program should cease to be rightful.


> Dr. David Gilbert scripsit:
> > What I am unclear of is shared libraries; is there something actually
> > copied into the result as part of the linking stage?  If I was to
> > a header for a GPL library so that I didn't make use of the GPLd header
> > could I then shared link it into a commercial app?
> The FSF says no, but nobody knows for sure: when the GPL was written,
> shared libraries were unheard-of.
> > Can I write a commercial app which is not linked with a GPL library but
> > opens it with dlopen at run time?
> Arguably this does create a derived work, at least in memory, thus
> violating the GPL.  (It is settled that the copy of a program
> that you make in loading it from disk to memory *is* a copy, and
> must be explicitly or implicitly licensed by the copyright owner.)
> --
> John Cowan                                   cowan at
> One art/there is/no less/no more/All things/to do/with sparks/galore
> --Douglas Hofstadter

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