List of delinker/unlinker tooling projects

[boricj]

This thread is for cataloging tools that can delink (or unlink) code.

Self-reported:

• boricj's ghidra-delinker-extension
• boricj's ghidra-unlinker-scripts (NOTE: obsoleted by ghidra-delinker-extension)

Reported by @widberg (#1 (comment)):

• endrazine's Witchcraft Compiler Collection
  • DEF CON 24 talk
• jonwil's unlinker
  • Announcement thread on forum.exetools.com
• jonwil's unlinkerida
  • Announcement thread on forum.exetools.com

Reported on Anda Pirate's Discord server:

• jnider's delinker

[encounter]

More specialized, but "unlinkers" nonetheless:

• encounter/decomp-toolkit: Specifically for GameCube and Wii (PowerPC), analyzes and splits game binaries into relocatable objects. Powers many matching decompilation projects.
• ethteck/splat: For N64, PSX, PS2 and PSP (MIPS). Also powers many matching decompilation projects. Emits assembly instead of writing relocatable objects directly, but that still counts, in my opinion.

Colloquially, the game decompilation community calls this process "splitting".

[boricj]

Interesting. I suspected there was some tooling out there, but I rejected perfect decompilation and every project out there seemed to go for it. I assumed I was off the beaten path and decided to do my own thing based on Ghidra, without looking at prior art.

My approach/implementation is too different for me to make comparisons after a cursory glance at these two repositories. It does appear that my Ghidra extension is focused on just one problem, but managed to solve it in a more general way.

Is there a forum/Discord server/something else for this sort of thing? I'm way out of the loop, but my distinctive take on this topic and my experience with it might be of interest to others.

[encounter]

Matching/perfect decompilation is hard, so I get it, but the results are quite cool! Tooling for non-matching decompilation (e.g. verifying functional equivalency without completely matching output) needs more exploration. (Maybe Ghidra P-Code could be of use?)

I think the Ghidra extension approach seems quite cool. Our approaches do differ quite a bit. For our projects, we focus on:

• Reproducibility: We don't want to distribute the game binary (or portions of it), so we rely on the user to provide it. The tooling uses a configuration file to inform the splitting process.
• Accuracy: We can get much better results by performing our own relocation analysis than relying on a more general tool like Ghidra, since we target a small number of compilers and compiler versions. Sometimes details as small as padding between objects can tell us where translation units start and end, and clever heuristics can eliminate a lot of manual work for the user.

This kind of work has been a focus of mine for a few years now, so I could ramble on 🙂

One of the more central communities is decomp.me (Discord), a site for collaborating on decompilation matches. This extension was mentioned a couple times in there. There's also the GC/Wii Decompilation Discord which has channels for the decomp-toolkit and objdiff projects.

[punpckhdq]

This is unpublished work, but for the past two years I have been writing on and off a standalone object splitter tool for x86 PE executables paired with debug .pdb archives.

I intend to rewrite this framework in order to support multiple architectures and an interactive binary diff/split interface, and then release it as open source software.

[boricj]

Looks neat. It seems like I've tackled this topic in a different way than the rest of the game decompilation community.

I will say that in my case, supporting multiple ISAs and object file formats in a decoupled manner is quite the challenge. I've managed to find a data model and an architecture that work mostly OK, but I still have a bunch of refactorings and clean-ups to do before I'll be happy with it. Also, this extension likes to silently break if given the chance, I've invested a lot into regression testing and it's barely enough to stop it from imploding.

Feel free to update your comment with a link whenever you release it.