detours-rs

Windows platform x86 hook library

currently only supported windows platform and arch x86.

code translate from Microsoft/Detours

Example

Hook address

use detours_rs::ext::Pointer;
use detours_rs::{Detours, transmute_void};
use parking_lot::RwLock;
use std::ffi::c_void;
use std::sync::OnceLock;
use windows_sys::Win32::Foundation::HINSTANCE;
use windows_sys::Win32::System::SystemServices::DLL_PROCESS_ATTACH;

static DETOURS: OnceLock<RwLock<Detours>> = OnceLock::new();

struct HookStruct;

type FuncHook = extern "thiscall" fn(&HookStruct);

const FUNC_HOOK_PTR: Pointer<0x123456, FuncHook> = Pointer::new_ref();

#[allow(non_snake_case)]
extern "thiscall" fn DetourHook(this: &HookStruct) {
    let Some(detours) = DETOURS.get() else {
        return;
    };
    let guard = detours.read();
    if let Some(detour) = guard.get(&FUNC_HOOK_PTR.addr()) {
        detour.trampoline::<FuncHook>()(this);
    }
}

#[unsafe(no_mangle)]
#[allow(non_snake_case)]
extern "system" fn DllMain(_module: HINSTANCE, call_reason: u32, _reserved: *mut c_void) -> bool {
    if call_reason == DLL_PROCESS_ATTACH {
        let detours = DETOURS.get_or_init(|| RwLock::new(Detours::new()));
        let mut detours_guard = detours.write();
        let Ok(mut guard) = detours_guard.lock() else {
            return false;
        };
        guard
            .attach_ptr(FUNC_HOOK_PTR, transmute_void!(DetourHook, FuncHook))
            .expect("failed");
    }
    true
}