[ccan] licenses (#9)

[Rusty Russell]

Stuart Henderson <notifications at github.com> writes:
> Many (though not all) of the files in ccan just have a 1-line reference to the license file, without any copyright information (author/date). I'm no lawyer (I just happened to notice this while looking at porting a project which includes some code from ccan) but my understanding is that these might be required in order for the license grants (which are intended to be done under copyright law) to be valid. Could you take a look into this sometime please and check if anything needs to be done? Thanks.

Hi Stuart,

        I have consulted with a lawyer on license boilerplate, but not
specifically the issue of author/date information.

In the end, there are two requirements for a license: enforcability and
usability.

I don't care too much about enforcability in some weird corner case; 99%
is good enough here.  Most certain would be including a complete copy of
the license in every file, but it's just not worth it (the CCAN Golden
Rule is "Our code must not be ugly").

Usability *is* important, and I had lawyers contact me to verify a
module license in the past.  Thus we now have the explicit LICENSE file
per module.  I decided to add a one-line reference as an additional
helper, as CCAN files are often cut & paste and it's a nice sanity
check.  So ccanlint insists on that, at minimum (license boilerplate
works too).

So, if there is a legal reason for author and date in a comment, perhaps
it's a regional (US?) enforcability issue, rather than a usability
issue, so I probably don't care.

Cheers,
Rusty.