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For example, if you distribute copies of the library,
whether gratis or for a fee, you must give the
recipients all the rights that we gave you. You must
make sure that they, too, receive or can get the
source code. If you link a program with the library,
you must provide complete object files to the
recipients so that they can relink them with the library,
after making changes to the library and recompiling it.
And you must show them these terms so they know
their rights.
Our method of protecting your rights has two steps:
(1) copyright the library, and (2) offer you this license
which gives you legal permission to copy, distribute
and/or modify the library.
Also, for each distributor's protection, we want to
make certain that everyone understands that there is
no warranty for this free library. If the library is
modified by someone else and passed on, we want
its recipients to know that what they have is not the
original version, so that any problems introduced by
others will not reflect on the original authors'
reputations.
Finally, any free program is threatened constantly by
software patents. We wish to avoid the danger that
companies distributing free software will individually
obtain patent licenses, thus in effect transforming the
program into proprietary software. To prevent this, we
have made it clear that any patent must be licensed
for everyone's free use or not licensed at all.
Most GNU software, including some libraries, is
covered by the ordinary GNU General Public License,
which was designed for utility programs. This license,
the GNU Library General Public License, applies to
certain designated libraries. This license is quite
different from the ordinary one; be sure to read it in
full, and don't assume that anything in it is the same
as in the ordinary license.
The reason we have a separate public license for
some libraries is that they blur the distinction we
usually make between modifying or adding to a
program and simply using it. Linking a program with a
library, without changing the library, is in some sense
simply using the library, and is analogous to running a
utility program or application program. However, in a
textual and legal sense, the linked executable is a
combined work, a derivative of the original library,
and the ordinary General Public License treats it as
such.
Because of this blurred distinction, using the ordinary
General Public License for libraries did not effectively
promote software sharing, because most developers
did not use the libraries. We concluded that weaker
conditions might promote sharing better.
However, unrestricted linking of non-free programs
would deprive the users of those programs of all
benefit from the free status of the libraries
themselves. This Library General Public License is
intended to permit developers of non-free programs
to use free libraries, while preserving your freedom as
a user of such programs to change the free libraries
that are incorporated in them. (We have not seen how
to achieve this as regards changes in header files, but
we have achieved it as regards changes in the actual
functions of the Library.) The hope is that this will lead
to faster development of free libraries.
The precise terms and conditions for copying,
distribution and modification follow. Pay close
attention to the difference between a "work based on
the libary" and a "work that uses the library". The
former contains code derived from the library, while
the latter only works together with the library.
Note that it is possible for a library to be covered by
the ordinary General Public License rather than by
this special one.
TERMS AND CONDITIONS FOR COPYING,
DISTRIBUTION AND MODIFICATION
A "library" means a collection of software functions
and/or data prepared so as to be conveniently linked
with application programs (which use some of those
functions and data) to form executables.
The "Library", below, refers to any such software
library or work which has been distributed under
these terms. A "work based on the Library" means
either the Library or any derivative work under
copyright law: that is to say, a work containing the
Library or a portion of it, either verbatim or with
modifications and/or translated straightforwardly into
another language. (Hereinafter, translation is included
without limitation in the term "modification".)
"Source code" for a work means the preferred form of
the work for making modifications to it. For a library,
complete source code means all the source code for
all modules it contains, plus any associated interface
definition files, plus the scripts used to control
compilation and installation of the library.
Activities other than copying, distribution and
modification are not covered by this License; they are
outside its scope. The act of running a program using
the Library is not restricted, and output from such a
program is covered only if its contents constitute a
work based on the Library (independent of the use of
the Library in a tool for writing it). Whether that is true
depends on what the Library does and what the
program that uses the Library does.
You may charge a fee for the physical act of
transferring a copy, and you may at your option offer
warranty protection in exchange for a fee.
a) The modified work must itself be a software library.
b) You must cause the files modified to carry
prominent notices stating that you changed the files
and the date of any change.
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