Comment by tigen
12 hours ago
What's the legal status of these?
Historically there was a notion of "clean room" reimplementation.
These days it seems people translate the actual game code into a different representation of that same code and that makes it open source? Github is full of these.
> Historically there was a notion of "clean room" reimplementation
These projects start off with the original assembly code and use it actively throughout all stages. This is about as far away from clean room as you get.
These projects do not start with assembly. They start with machine code interleaved with data. Even getting to assembly through a disassembled requires some input and understanding. Usually these are raw binaries with no (or limited) metadata.
When run through a disassembler, in most cases, it’s probably the first time anyone has ever looked at the assembly (assuming PlayStation or newer). There are no comments or labels or symbols. Not what most people would consider “the original assembly”.
The term "original assembly code" is sufficient enough to communicate that the binaries that are being reversed are what is disclosed to the public intentionally.
Their comment still stands; whether it's machine code or "original assembly code" that shipped on the disk it falls under "clean room" reversing and by extension implementation.
Ghidra is able to figure out the functions in around 99%++ of cases though
It seems like it could go either way to me in the US (not a lawyer, but someone who has a fair amount of experience in reverse engineering / fair use issues).
On the one hand, it is fairly clear that producing source code with the explicit goal of reproducing a 1:1 binary is in no way transformative, so that's out. This would be a really hard argument to even attempt.
On the other hand, these projects are mostly free, intended for owners of the game to play the original game on a different platform or in a modified format, and not likely to have a negative effect on the original work's desirability or value. And, the reproductions aren't complete and alone usually produce limited to no value to a consumer (usually, they won't start without the original game files). These are the other important factors considered in fair use determinations and generally go the way of these being OK.
So, it's hard to say. With reverse engineering and copyright in the US in general, context is crucially important; something that would be completely illegal for one purpose (ie - decompiling and recompiling a competitor's software to distribute it without a license or use it internally without purchasing it would be obviously illegal) could be OK for another one.
In a sane world, if brought before a court, the binary itself wouldn't have any protection unless hand authored. The actual creative work/human expression was the source code. The entire point of compiling is to strip that extra data out, leaving pure functional logic that doesn't even strictly match the source logic thanks to optimization.
Then a freshly written project would be completely different with no derivative elements at all; the only commonality between the two codebases is their functional elements. You can compile a decomp into the same binary, but that's only to prove functional equivalence. The intended mode would be with a modern compiler that completely rewrites the logic (it might even have to if it writes it for a completely different computer architecture, which describes every retro console game). Then neither the source nor the compiled artifact would match.
> The entire point of compiling is to strip that extra data out, leaving pure functional logic that doesn't even strictly match the source logic thanks to optimization.
I strongly disagree with this notion from even a conceptual (much less legal) level; the point of compilation is not to erase the algorithms the programmer implemented, just to optimize and implement them.
> You can compile a decomp into the same binary, but that's only to prove functional equivalence.
This is like saying that a translated book is only "functionally" identical to the original; there's a lot of precedent in copyright law for this not being the case, and I don't think any argument revolving around the transformativeness of the compilation process would fly at all.
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> it is fairly clear that producing source code with the explicit goal of reproducing a 1:1 binary is in no way transformative, so that's out. This would be a really hard argument to even attempt.
Absolutely false. There are an infinite number of programs that will compile to the same machine code. Especially when an optimizer is involved. Discovering one of those is a creative process, transformative, and protected.
Using an LLM to do it for you? I wouldn’t touch that with a 10 foot pole. Seems too close to mechanical transformation to me.
Clean room might get you past copyrighted code, but surely it won't get you past trademarks or copyrighted artistic work?
Most of these projects carefully distribute only the source code representation of the binaries, for this reason, relying on the consumer to acquire / own the art assets and copyrighted material (logos, trademarks, etc.).
The code assets are just as copyright encumbered as the art assets.
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There was a decompilation project of GTA 3 and Vice City. It got DMCAed by Rockstar Games, despite requiring the user to provide their own game assets.
Historically these projects have gone to match byte for byte recreations which ensures that they are derivative works making them infringing copyright.