On 11/09/2012 02:35 AM, "Claes Wallin (韋嘉誠)" wrote:
Sorry for bumping this discussion thread this late, but I discovered the Berkeley DB license* ("the BDB") and it made me think about what had been said here.
https://www.gnu.org/licenses/license-list.html#BerkeleyDB
Haven't looked at the BDB before, and I find it interesting. Taking into account only the numbered points, it might be the shortest example of a copyleft license in use in the field, even close to the shortest possible. It's close in form to a BSD-like license plus source requirement.
I'm not sure it's truly a (free software) copyleft license, though it's something similar. It says that the source code that you have to provide must be "freely redistributable under reasonable conditions". Does this mean that the conditions in the redistributor's license must allow royalty-free modification, say? I suppose I would argue yes, because of how I believe the term "freely redistributable" was understood in the 1990s.
The FSF claims that the BDB is GPL compatible, I assume because it does not specify anything outside the bare minimum, in particular does not restrict any "further restrictions".
The FSF (assuming the FSF analyzed the case carefully) must be assuming that the word "uses" in "any accompanying software that uses the DB software" would never lead to a result in which you'd have to provide more source code than you'd have to in a standard GPLv2 situation (as the FSF would interpret that). In other words, the FSF must be assuming there is an implied "mere aggregation" limitation on the source code requirement.
Does it even propagate a guarantee of the four freedoms to modified versions of the software?
I think this depends on how you read "freely redistributable under reasonable conditions".
It's worth noting that the Sleepycat License was designed with what bkuhn would call a 'proprietary relicensing' business model in mind (at least based on the historical material I recall seeing). I suppose if that's true it might seem to suggest that the Sleepycat License was meant to be read as having a *broader* copyleft-ish scope than GPLv2 (which would imply that the FSF seemingly erred in classifying it as GPL-compatible). (Why else would Michael Olson or whoever wrote the license not have just used GPLv2? Berkeley sentimentality?)
- RF