Here, let me exchange the White House for you.

Do you see the difference between providing the medium and providing a link to it?

There are at least three problems with your interpretation. First, the binary form of the software appears to not include any offer to provide source code, so the $3.99 cost for a binary copy is not easily interpreted as the cost to provide a copy of the source code. Second, the language of the GPL specifically limits the cost to the "cost of physically performing source distribution"; the inclusion of the qualifier "physically" arguably excludes imputed labor costs. Third, to the extent that the language is ambiguous, US courts are supposed to interpret ambiguous clauses in standard form contracts against the party offering the contract, and there is room to view the distributor either as the party who accepted the GPL or the party who offered it (to the end user).

I sent a support request to the distributor asking where the source code is. Depending on the response to that, I might complain to Google and/or the DosBox developers. I would rather have the distributor mend his ways with as little third-party pressure as possible; I think that usually leads to a better FOSS environment in the long term.

I paid $3.99 for a copy, but that still does not give me any legal rights under the GPL; the GPL is between a distributor (the DOSBox Turbo guy) and the authors (contributors to DosBox) of a piece of software. The issue is that the distributor has not satisfied the terms of the license that allows him to create and distribute his derived work -- those do not allow him to sell binary copies and then only give source to people who paid for the binary.

As a point of fact, the GPL does not "specifically allow[]" you to make the source code available only to users who pay for a binary version. GPLv2 offers three choices when distributing a binary work covered by its terms: 3(a) accompany the binary version with the source code; 3(b) accompany the binary version with an offer to provide the source code to anyone, at no more than your cost to distribute the source; or 3(c) -- for non-commercial redistribution of binary forms -- with the same offer that one received according to 3(b).

What is "actual instantaneous amortized cost" supposed to mean? $3.99 is certainly not his marginal cost -- and I am confident it's more than his overall amortized cost for the resources involved -- and requiring someone to pay for a binary version before you fulfill their request for source code is certainly not compliant with the wording of the GPL.

Okay, I spent the $3.99. As far as I can tell, the binary install does not include source code; the only related file I can find is an 8.5 MB binary blob, apparently encrypted (it's in an ".android_secure" directory and "strings" doesn't show any apparent English text). When the application runs, it does not appear to provide any link to the corresponding source code, or any contact information to request the source code. The only way I found to contact the distributor is to go through Google Play. So: Do you still think this turkey complies with the GPL?

So, I did pay the $3.99 for DOSBox Turbo, installed it on my phone, and moved it to the SD card. When mounting that as a disk drive, the only thing I can see related to "dosbox" is .../.android_secure/com.fishstix.dosbox-1.asec, an 8.5 MB binary file that is apparently encrypted. When I run the application itself, it does not include anything that looks like a link or other offer to the corresponding source code. My conclusion: This is a clear and blatant violation of both the letter and the spirit of the GPL. Now will you admit that you're wrong?

I have never claimed that a link is the source code -- a link is also not the binary form. Debian provides equivalent access to the source and binary packages; for convenience, the installer software only accesses the binary packages, but that does not affect their compliance.

The DOSBox Turbo distributor provides neither source code, nor a written offer to provide the source code, for the work that he distributes. That work is derived from a GPLv2-licensed work, and his failure to comply with the terms of the GPLv2 is the violation.

I would rather say that the GPL draws a distinction between "free as in beer" and "free as in freedom", explicitly recognizing the importance of the latter. The DOSBox Turbo web site's explanation of why it is "not free" does not even mention the freedom aspect, which is why I think it is inconsistent with the spirit of the GPL (in addition to being apparently in violation of the letter of the GPL). Stop with the apologetics for GPL violations!

A distributor of a binary using GPLv2 section 3(b) only has to provide the written offer (for source code) when they distribute the binary -- but that offer must allow any third party, whether the third party received a copy of the binary or not, to get complete machine-readable source code corresponding to the binary at the "cost of physically performing source distribution". It is flatly incorrect to say "only when you receive the binary you are legally entitled to also get the source code".

A link is not the source code; it is more like an offer to provide source code later. One must do something more than provide a URL to satisfy section 3(a) of the GPLv2. For example, Debian handles it by having source packages on the same servers as the corresponding binary packages -- this satisfies Debian that the source and binary packages are on the same "medium customarily used for software interchange", and that the user has a sufficient chance to download the source code for any binary they get. For something like Google Play, it does not seem feasible for a user to find source code for a given app package unless the source code gets installed at the same time as the binary (and it is later reasonably easy for the user to read that source code).

The DOSBox Turbo web page says that it is licensed under the GPL, and also has a FAQ explaining why it is "not free". That does not seem like compliance with the spirit of the GPL. If you think he does complying with either the spirit or the letter of the GPL, why don't you pay $3.99 to confirm your guess?

I don't want to spend $3.99 because it seems too likely -- based on what others have done in similar situations in the past -- that he would not provide complete corresponding source code for his version and/or he would claim that some of his extensions are under GPL-incompatible licenses (such as "all rights reserved"); whether that is the case or not, I would not get $3.99 worth of value (to me) from either the binary or the source code of the app.

GPLv2 says that it must be in a machine-readable form on a medium customarily used for software interchange, and that the cost charged for a copy of the source code must not exceed the "cost of physically performing source distribution". This prohibits additional considerations such as the diamond-encrusted USB key or employing a large number of Vatican virgins.

The company's probable legal reasoning would be that it merely provides the employee with access to a company-owned system that includes the software, which would mean that the company has not distributed the software within the meaning of the GPLv2. This kind of claim is only tenable where the company owns the system (or perhaps in some other cases where the individual in question is acting as an agent of the company, under the usual laws of agency); it would not hold if a copyright owner wanted to press a case against a "private members area", regardless of how the latter tried to constitute or describe itself.