Comment by bri3d
11 hours ago
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.
A huge portion of the actual thing I write when writing a program does not exist at all in the compiled binary. Names, types, type parameters, etc. being big ones, but many types are also aliases for the empty struct, so their value doesn't exist at runtime either. Conversely, I can write _.map(_.map(_.map(f))) and have that turn into all sorts of looping and branching logic that I didn't write, and the meaning of which is basically "do whatever must be done to make the types work".
Programs as written are nothing like programs as compiled, certainly not as an expressive endeavor. Books don't have an analog. There's no point where we strip all conceptual meaning from the book and leave only the procedural algorithms the semantics demand. There's no point where we replace all the individual words with autovectorized versions, or where we automatically delete impossible sentences, or remove every layer of abstraction that the programmer put in there exactly for the ability to convey ideas.
> 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.