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.