Spotting GPL violations

Philip Webster phil at
Sun Dec 12 14:45:03 UTC 2004

Jeroen Dekkers wrote:
> At Sun, 12 Dec 2004 12:03:07 +0000,
> Philip Webster wrote:
>>I was under the impression that any code which links directly to a GPL'd 
>>library is essentially using part of a GPL-licensed work in the form of 
>>the method names it is calling, and as such by directly linking, becomes 
>>in itself a 'derivative work' which must be GPL licensed in order to be 
>>legally distributed.
> That's indeed right. The problem is that I can't really make that up
> from the homepage. But if this is what the software does, then it is a
> GPL violation.
> Jeroen Dekkers
I've contacted the author, and raised the points we have both covered on 
this list. I can report that this is in fact NOT a GPL violation, or at 
least so far as I can see. Here's how the RISC OS interface works:

GemPrint (the proprietary interface) links !Printers (the RISC OS 
printing system) to GIMP-Print (a Free printing system which supports 
many more models of printer than !Printers ever could.) !Printers is 
proprietary, and GemPrint links to it using what are essentially RISC OS 

The link between GemPrint and GIMP-Print is done via a temp file. A RISC 
OS application invokes !Printers by requesting that something is 
printed, and !Printers calls GemPrint. GemPrint saves GIMP-Print 
compatible data to a file, and GIMP-Print comes along later, sees the 
file, and prints it.

GemPrint is careful never to directly invoke the GPL-licensed library at 
any time.

As far as I'm concerned, this means there is no GPL violation. Unless 
you can see anything wrong with the system as described above.


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