Comment by mschuster91 | Hacker News Reader

Comment by mschuster91 | Hacker News Reader

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It's not possible in the most cases - unless you have the exact same version of the compiler that was used and you can figure out the build settings that were used (especially optimizations, but also stuff like include order), you can't recreate the assembler code from pseudo / C code.

Modernizations are especially tricky. Modern compilers can do all sort of weird magic, sometimes combining two or more lines of code into one instruction. Old school compilers don't optimize much which is part of why performance-critical parts of game engines were written in Assembler for a long time.

Not to mention that some stuff you can do in Assembler has no equivalent in higher-level code (e.g. dealing with raw stack frames), and even Assembler to byte code is nowhere near 1:1 reversible.

You might not get the exact same code, but it is certainly possible to generate C/pseudo-code from the binary.

IDA Pro and Ghidra can identify functions and generate the equivalent C code. I know that this is not the original code, but it does help a bit when you are trying to get an idea of what a large function doing.

You're both right.

I've used Ghidra to reverse-engineer a game's serialization format[0] and, even though the C-ish result was marginally better than manually tracking registers across the disassembly, it was far from understandable.

A great deal of the work was cleaning up the resulting C into something that a human would've written instead of the garbage ASM-with-C-syntax that Ghidra produced.

That is nowhere near what OP was suggesting (although useful nonetheless).

[0] https://github.com/alvaro-cuesta/townsclipper

I'm actually reverse-engineering a game myself... interestingly, for me Ghidra produces very good results, way better than IDA did ten years ago. On the other hand I may be lucky simply because 1996 Borland C++ is a pretty dumb, unoptimizing compiler and there is absolutely no copy protection or whatever present in the game, not even a dead code elimination.

Only thing where Ghidra lacks any form of knowledge of is how to deal with the FS register that is used for SEH on win32... it just marks it as in_FS_offset with no way to tell it that it can replace FS:[0xXX] with appropriate TIB access macros.

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