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Re: anti-tarball clause and GPL

On 24.07.2019 00:49, Adam Borowski wrote:
In the light of the currently discussed GR proposal, I wonder if the
following license clause would be considered DFSG-free and GPL-compatible:

I do not consider a flat tarball to be a preferred form for modification.
Thus, like any non-source form, it must be accompanied by a way to obtain
the actual form for modification.  There are many such ways -- unless you
distribute the software in highly unusual circumstances, a link to a
network server suffices; see the text of the GPL for further details.

I believe such a statement would be GPL-compatible; rationale:
* by the 2011 Red Hat kernel sources outcry, it is obvious such a tarball
   is long obsolete
* a flat tarball deprives the recipient of features of modern VCSes
* comments giving rationale for a change tend to be written as VCS commit
* future forms are not banned: it is conceivable that next week someone
   invents a revolutionary new form that wins over git


Few comments:

A "flat tarball" cannot be considered a preferred form for modification. Few tools allow you to edit a flat tarball (maybe `mc`). It is just a form of distribution. We sent to GNU patches, new files, or extract of functions.

I think you confuse the "preferred form for modification" to "preferred method of distribution of sources".

Compression of tarball often change, so we need "new" (less than 10 year old) tools to extract many tarball (tarball format also had few improvements). GPL do not restrict format and compression of tarball. Early GNU programs come with many different distribution methods. 'tar' is much modern (so initially on "modern GNU" systems). The tar was never considered as only (or main) method to obtain sources.

IIRC from very old discussion, you can have a GPL compatible distribution method of your choice, if you distribute tools to extract sources, or such tools are easy available to the user who bought your software. There is no need to have free tools: if you distribute binaries for Solaris, it is enough that user could use a proprietary Solaris command to get the source.

Note: tarball are often not GPL compliant, because we are lazy. VCS solves most of the problems (or helps):

GPL requires us to have and distribute a changelog, so that we can track better licenses, modification time, and copyright. Debian requires own changelog (we use GPL for Debian stuffs), but as we saw, upstreams often forget it. In such cases (without changelog) a tarball cannot be considered fully GPL compliant.


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