From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 9633 invoked by alias); 28 Feb 2002 10:21:21 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 9508 invoked from network); 28 Feb 2002 10:21:14 -0000 Received: from unknown (HELO web13304.mail.yahoo.com) (216.136.175.40) by sources.redhat.com with SMTP; 28 Feb 2002 10:21:14 -0000 Message-ID: <20020228102114.59731.qmail@web13304.mail.yahoo.com> Received: from [194.203.213.161] by web13304.mail.yahoo.com via HTTP; Thu, 28 Feb 2002 02:21:14 PST Date: Thu, 28 Feb 2002 04:04:00 -0000 From: James Michael DuPont Subject: Linkage of GPLed GCC to Closed Source via XML or Perl To: gcc@gcc.gnu.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-SW-Source: 2002-02/txt/msg01794.txt.bz2 Dear GCC Developers, For the past three years, I have been working on a project to create a object oriented interface to the GCC compiler, the GCC Node Introspector (http://introspector.sourceforge.net/). This turned from a c++ into a Perl project after realising the power of Perl for handling strings and complex data structures. Currently I am using a modified version of c-dump.c like done in CPPX (http://swag.uwaterloo.ca/~cppx/doc/cppx/arch.html). I output the tree nodes into a XML form that is very similar to the tree dump, just with xml syntax. This is streamed into a Perl program via popen and written to a Postgres database. Also the number of tools that link into perl are amazing. The linkage of Perl is permissive, but I think that the linking of programs can to GPL code can be very tricky, and full of problems as a detailed review of the GPL and LGPL can point out. In this article : http://lwn.net/2001/features/LarryWall/Perl >> CL: Would you give us an example of cultural problems? >>Larry Wall: Ten years ago or so, we had Richard Stallman's GPL, and Perl was licensed under that. And I discovered >> that that worked fine for the hacker community, for the geeks, but it prevented Perl from being used in a >> commercial environment. So I wrote my own license. But I didn't want to offend the free software, the GPL >> people. >>So, rather than switching licenses, I said "Well, let's have both licenses and you may distribute Perl under >>either of them at the same time." And that way, the computer crowd, they had their insurance that their rights >>would not be taken away, and the companies had some insurances that their rights would not be taken away, and >>everyone was happy. That's sort of cultural hack that I'm talking about. Does that mean that via perl a company can create a close-source gcc backend? Without external representation via XML? Let us review the the GPL and its implications for linking to Perl : Lets look at the GPL : >This General Public License does not permit incorporating your program into proprietary programs. >If your program is a subroutine library, you may consider it more useful to permit linking proprietary >applications with the library. >If this is what you want to do, use the GNU Library General Public License instead of this License. My GPL Comment: incorporating is a term that implies to me containment, If I write a proprietary program that uses the output of the GPL Code is that containment? If I open the a pipe to another program, and call functions in it using data from a GPL program, is that not what a linker does, but via a different method? Lets look at the LGPL 2.1 > We use this license for certain libraries in order to permit linking those libraries into non-free programs. > When a program is linked with a library, whether statically or using a shared library, the combination of the two is legally speaking a combined work, a derivative of the original library. >The ordinary General Public License therefore permits such linking only if the entire combination fits its criteria of freedom. > The Lesser General Public License permits more lax criteria for linking other code with the library. LGPL Comment : Now this does not cover linking via RPC/IPC or Shared Memory or File. Let alone CORBA or XML-RPC/SOAP. This comes done to the definition of linking, is linking only with the linker, or is linking a method of passing data between function calls? Can I call a GPLed Function in GIMP via a perl script webpage, but I cannot link to it? LGPL part 2 : >14. If you wish to incorporate parts of the Library into other free programs whose distribution conditions are >incompatible with these, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this. >Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally. LGPL Comment part 2 : "distribution conditions are incompatible with these" Does that cover PAL which gives you more freedom? Can I link via Perl and all of a sudden, there is no more GPL? By these terms, would every Perl script which links in with GPLed GIMP via script would require such permission to be asked? The perl script is called from an apache server, goes across all types of close-source maybe even patented software sitting on routers and switches, and then gets displayed in a microsoft browser, only to call a javascript function that uses the microsoft api to draw on some graphic card. As you can see, the network has changed the meaning of linking. Perl has changed it as well. Also see the discussion of this subject on perl monks http://www.perlmonks.org/index.pl?node_id=148162 James Michael DuPont mdupont777@yahoo.com ===== James Michael DuPont __________________________________________________ Do You Yahoo!? Yahoo! Greetings - Send FREE e-cards for every occasion! http://greetings.yahoo.com