🚀 go-pugleaf

The intent of the GPL regarding ftp and download access is stated in
this paragraph (from version 2):

    If distribution of executable or object code is made by offering
    access to copy from a designated place, then offering equivalent
    access to copy the source code from the same place counts as
    distribution of the source code, even though third parties are not
    compelled to copy the source along with the object code.

Some people have asked whether the sources have to be on the same
directory, or on the same machine, or what.  I can't remember thinking
about this before, but it appears that I did: the phrase "offering
equivalent access" seems to be a good rule.  This says that the
details of where the source is kept don't matter as long as you
yourself can offer access to copy it.

For ftp, the sources could be at another institution in another city,
as long as *you* can offer access to the sources there (with their
cooperation, presumably) for as long as you keep offering access to
copy the binaries.  (Another country might not be okay because in
practice the access is probably not equivalent from your country.  For
telephone download, the site shouldn't be too far away geographically
from yours.)

What is not okay is simply pointing people at another place where the
source was *at one time*.  Because if one day the source is no longer
there, then on that day you will be distributing the binary without
offering access to the source.  We all know that this is very likely
to happen if you and the other site don't make explicit arrangements
to prevent it.

What you should do, if you want to provide the source "from elsewhere",
is to make arrangements with a source archive site so that they will
keep the source available for as long as you keep the binary available.
(The access offered by the two sites must be equivalent in other
respects.  Also, since you effectively offer the binary access to any
user who browses your system, you should put a file near the binary
explaining how to get the source, to make sure you offer the same users
source access at the same time.)

In principle, the FSF could play the role of the source site for this.
In practice, we can't, for two reasons: we don't have enough disk
space to keep old source versions, and we can't undertake the
administrative burden of making these arrangements--it would be too
much trouble if we had to negotiate with a number of sysadmins before
deleting any version of the source.  But there are many source archive
sites, and probably several of them will make such arrangements, thus
splitting up the burden.

The rest of section 3 is not as clear as I would wish, and it's possible
that it can be interpreted to have a loophole.  I will probably make this
clearer in the next version of the GPL.

Finally, I'd like to urge people not to overestimate the importance of
one binary archive site more or less.  There are plenty of archive sites,
so people's access to the software is not dependent on any one.
It's better to have five sites and offer source properly through each one
than to have ten sites but with haphazard source access.