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Comment by tambourine_man | Hacker News Reader

How legal is decompilation? Have we stablished legally accepted ways like in reverse engineering?

It’s legal under the DMCA for the purpose of interoperability… but IANAL:

https://www.law.cornell.edu/uscode/text/17/1201

The parts that refer to interoperability all use phrasing like "interoperability of an independently created computer program with other programs". That "independently created" probably doesn't apply here.

I would consider this project to be aiming for interoperability with the target OS (Linux, macOS, Windows), an independently developed program.

By that interpretation, you would be free to use information gleaned from reverse engineering Super Mario 64 to modify your OS of choice to be capable of running Super Mario 64 as-is. But the law doesn't authorize you to distribute a modified version of Super Mario 64, because the reverse engineering is only permitted "to the extent that doing so does not constitute infringement under this title or violate applicable law other than this section."

I would assume it falls under the same rules regarding the ROM itself: legal to do yourself from a purchased copy but not legal to send to others.

I am unsure about the exact legal details about decompilation, but in regards to the SM64 decompile the fact it produces a rom that is byte for byte exact I doubt it to be legal

From the SM64 decompilation (https://github.com/n64decomp/sm64) 's README:

> This repo does not include all assets necessary for compiling the ROMs. A prior copy of the game is required to extract the assets.

In other words, the repo only contains the reverse-engineered source code, not any reproductions of Nintendo's copyrighted or trademarked materials. You have to produce those infringing assets yourself—using tools they supply, yes; but also, crucially, by feeding in a copy of the game you already—presumably—have a private-use license for.

Thanks, yeah, I was thinking along those lines: of course Mario 3D models, textures, audio, etc, are Nintendo’s copyright, but what about the decompiled code itself?

That seems a much harder line to draw

IIRC there have been court rulings that using someone else's data but in your own structure (e.g. someone else's geo-referenced place named but structured into your own map; or someone else's database of phone numbers but structured into your own phonebook) is perfectly legal, and not a copyright violation.

The decompilation process didn't result in C source code that exactly matches the C source code that Nintendo wrote. (For one thing, the identifier names are different. Probably they use different-but-equivalent control structures in places. Intermediate variables might be introduced that didn't exist in the original.) And as such, that code isn't something Nintendo owns.

This is why the Oracle vs. Google Java lawsuit had to be about header files that were copied verbatim — because Oracle had no grounds to stand on for suing for infringement for the reverse-engineered-and-rewritten implementation code.

(Note that Nintendo could in theory have patented some of the high-level process stuff going on in their code; but that's rare and unlikely enough in litigious America, let alone in Japan.)

The decompiled code is a derivative work of the ROM which is a derivative work of the original code.

Meaning, illegal from your point of view?

There are infinite possible compiler inputs that would produce an exact copy of the ROM, or a superset of it. Pi is likely to be one of them. Would all such inputs infringe on Nintendo's copyright?

This is such a nonsequitur.

I can take something copyrighted, and generate an unlimited number of different things that infringe copyright. I could take Harry Potter and change where the line breaks are—countless variations. Or I could add commentary to the margins. I could put different pictures on the cover. I could translate the book into different languages. I could write new chapters and stick them in the middle.

The question is if the compiler input was made (in part) by copying something from Nintendo.

How legal are derivative works on GitHub with copilot? They can have rules, enforcement is separate.

They are illegal, but github will leave them up until someone sends a dmca request / enforces their copyright.

Didn't EU just drop a ruling regarding decompilation?

Decompilation to fix a bug or otherwise allow the software to be used as intended. Not just decompilation for the fun of it or running it on completely unsupported hardware or software.

https://news.ycombinator.com/item?id=28809559

Can you argue that you intended to use the software on your iPad?

On the surface maybe, but

> such an exception to the author’s exclusive rights may not be used in a way which prejudices the legitimate interests of the rightholder or which conflicts with a normal exploitation of the program

could be interpreted to mean that, especially for anything still being sold (like the retro games sold on Switch), interop for the sake of interop would very likely conflict with Nintendo's legitimate [business] interest.

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