GSDJVU is a CPL licensed driver for GhostScript (AGPL). According to DjvuLibre, it is legal to download the source code for both and compile them, but not to redistribute the compiled program due to incompatibility between CPL and AGPL.

Which clauses of the CPL and AGPL prevent redistribution of a program compiled from CPL and AGPL source code? DjvuLibre say it's due to their redistribution requirements, but GNU don't mention this as a point of incompatibility. Would it not be possible to jointly license the compiled program under both CPL and AGPL? Or to create a new license for the compiled program that satisfies the conditions of both?

If not, would any workarounds be possible, such as:

  • Creating a wrapper for the GSDJVU drivers that call an external binary (i.e. the CPL licensed driver algorithms), and distributing the compiled GhostScript-with-wrappers under AGPL, and a separate GSDJVU driver binary under CPL? (assuming this is technically possible)
  • Creating a diff patch from GSDJVU that could be applied to compiled GhostScript executables, and distributing the diff patch under the CPL?
  • Distributing a script that downloads the relevant source code (both CPL and AGPL with suitable disclaimers) and compiles it to produce GSDJVU?

DjvuLibre say that GhostScript is also available under the GPL, but I haven't been able to confirm if this is still the case, unless they mean the interoperability between AGPL v3 and GPL v3.

It would make life much easier if AT&T did relicense GSDJVU under a GPL compatible license, but after more than 18 years of them failing to do so, it seems pretty unlikely.

  • If you're willing to use version 9.07 or earlier of GhostScript (dated 2013) then you can distribute under the GPL.
    – doneal24
    Aug 9 at 15:22
  • "Creating a wrapper ..." - This is what the GNU debugger does to include proprietary hardware drivers. So it should not be a license issue ... but probably a lot of work. "Creating a diff patch ..." - I doubt that this is possible at all. "Distributing a script that downloads ..." - as far as I know, no license (AGPL, CPL) can forbid you to distribute the script; however, running the script might be problematic especially if the operator of the server forbids scripted downloads. Aug 9 at 15:40
  • @doneal24 that explains it! 9.07 would be fine for building gsdjvu, but I guess the licensing compatibility may still be a problem? Aug 9 at 16:20
  • @MartinRosenau re diff patches: do you mean not possible for licensing reasons? Aug 9 at 16:23
  • 1
    @Brandin that would make it much easier for AT&T to make it compatible, but the EPL 2.0 FAQ seems seems to say that adding the secondary GPL license would require permission from all copyright holders: eclipse.org/legal/epl-2.0/faq.php#h.fn86eyf5mvhs Aug 10 at 18:04


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