[e12e]

> == Tarsnap ==

> How to write C. Study the "meta," that is, the choice of how the

> codebase is structured and the ruthless attention to detail. Pay

> attention to how functions are commented, both in the body of the

> function and in the prototypes.

I just had another look at the tarsnap source code, and while I know Percival is a great guy, and I can't imagine him suing over "mis-use", the bulk of the code is under a pretty restrictive lisence:

"Redistribution and use in source and binary forms, without modification, is permitted for the sole purpose of using the "tarsnap" backup service provided by Colin Percival."

That is, except the code under "libcperciva" which appears to be under a traditional 2-clause BSD license.

So, for example using the bsdtar.c file to teach yourself how to handle command line arguments might be a bit dicey, as it's entirely unclear which part of that file is under the BSD license, and which part you're not allowed to distribute.

It's one of the reasons why I'd which Percival made the entire thing available under a dual license (eg: BSD) and simply required people to use the official client for the tarsnap service.

Then again, I'm not used to audit closed source software, and therefore probably extra scared of what might happen if I accidentially learn something from reading said source... ;-)

On the other hand, Percival does publish quite a lot of stuff that's [ed: entirely free], such as spiped https://www.tarsnap.com/spiped.html .

[supercoder]

Relax

[sillysaurus3]

Actually, it's an important point. One way to learn a given coding technique is to copy-paste it into your own project, modify it until it works, and then delete it and re-implement it yourself. (The "delete and then reimplement it yourself" is the important part. Don't just copy-paste code!) That way you can build up an understanding of the code as you go, without having to understand it in its entirety from scratch. Understanding it in its entirety from scratch is the better way, because it gives you a deeper understanding, but people learn in different ways.

Anyway, illegal is illegal, and copy-pasting from Tarsnap would be illegal. I didn't know Tarsnap was under a restrictive license. It's a shame that people will have to be so careful when learning from Tarsnap, as it's a paragon of modern C best practices, but maybe the license is shrewd.

Though I wish the mentality of "my competitors might steal the code!" will die its deserved death, since evidence thus far suggests it's just paranoia. For example, the codecombat guys open sourced everything and have been fine: https://news.ycombinator.com/item?id=7015126 (But of course that's easy for me to say when I have no competitors to worry about!)

[cperciva]

Though I wish the mentality of "my competitors might steal the code!" will die its deserved death, since evidence thus far suggests it's just paranoia.

Well, Tarsnap is online backup for the truly paranoid... ;-)

Seriously though: I never thought this was likely to be a problem, but given that I was spending a significant chunk of my life on this, I wanted to eliminate obvious risks to my livelihood. I like not starving.

But I've done my best to put the "reusable for a purpose other than building Tarsnap" code into the separate libcperciva tree. And I'm sure that merely reading code to learn from it is not a copyright violation -- there are no laws about copying information into your brain, thankfully. So please, read the code, and email me if you see any bugs; I wouldn't be offering bug bounties if I didn't want people to look at the code!

[Locke1689]

I suspect that your suggested use of the code would fall under the fair use statute in 17 U.S.C. § 107 and the guidelines from Folsom v. Marsh since it seems explicitly for pedagogical or research purposes.

IANAL, but if this were me it seems safe enough that I'd be willing to do it and fight Colin in court if need be. :)

[sillysaurus3]

When I first started programming, a lot of the licensing rhetoric seemed like much ado about nothing. "Look at all these people squabbling about who's allowed to do what with text! It's text! Sheesh!"

But one quickly realizes that the concept of software license restrictions is a fundamental reason for the strength and momentum of open source software. Therefore, it must be true that a central tenant of being a good developer is to respect software licenses. Not merely respect them to the letter of how they're written, but to respect their spirit as well. If an author wishes you don't do something with their code, then you don't do it. There are plenty of reasons why this should be the case, but the most compelling for me is that it'd be lame to ignore the author's wishes while using their work, even if the author won't ever know about it.

If people are still feeling tempted to lift code, well... Remember that you only get to destroy your reputation once.