ipbp.rs - in place binary patching

Patch rust functions at runtime with magic and linker hacks.

how it works

roughly:

• diff object files
• figure out what exactly changed
• combine the changed object files using the dep map
• figure out affected symbols and functions
• package the .o files together into a single cursed dylib that tricks dlopen
• disable a bunch of stuff like ASLR
• dlopen that dylib at the same address as the program root itself such that our pic/pie code can work properly
• resolve missing symbols against the running binary
• tell the app that we've patched it and it should maybe try to do new stuff

and voila you have in-place binary patching for a running rust app.

Not only does completely circumvent the typical close, rebuild, relink, restart, reinitialize, resume flow, but it uses rust's incremental compiler WITHOUT LINKING - the only unnecessary cost we pay here is the compiler frontend + macro expansion. This is faster than pretty much anything else you could design.**

** currently uses the linker in a sort of pass-thru mode. we still need to handle compilation-level relocations. eventually will drop this entirely.

Notes

• dlopen seems to be working on ios?

• https://gitlab.com/turbocooler/dyld-trie

• https://crates.io/crates/formatic

• https://github.com/Toni-Graphics/Formatic

• https://fasterthanli.me/series/making-our-own-executable-packer/part-18

• https://docs.oracle.com/cd/E19683-01/816-1386/chapter6-54839/index.html

• https://davidlattimore.github.io/posts/2024/02/04/speeding-up-the-rust-edit-build-run-cycle.html

ummmmmmmmmmmmmmmm

• https://stackoverflow.com/questions/495262/linking-symbols-to-fixed-addresses-on-linux

can't we just define the existing symbols - except for the target - from the already resolved symbols in space?