Expand description
Utilities for referring to functions by pointer.
Using the getfn! macro, you can generate a pair of functions: the first
function acts as a “getter” function, and is prefixed with getfn_. The
second function simply calls the function normally:
use getfn::getfn;
getfn! {
(|| { println!("hi!"); })
fn my_func();
}
my_func(); // hi!
let f = getfn_my_func();
f(); // hi!You might be wondering why not simply use let f = my_func; instead of
having a separate getter. The reason is that the resulting function pointer
in f will not have the exact same address as the one passed into getfn!.
This is necessary in cases like game modding, where to hook a function,
you must have its exact address. To aid these usecases, getfn also offers
a get_addr! macro, which is a DSL for getting the address of a function:
// gets the base address of the `MyGame.exe` module using the backend
// (currently assumed to be `winapi` accessible from `crate::__getfn_winapi_`)
let f = getfn::get_addr!("MyGame.exe" + 0x20bf00);These can be combined together using the symbol_fn! macro:
use getfn::symbol_fn;
use std::ffi::c_void;
symbol_fn! {
("MyGame.exe" + 0x20bf00)
extern "C" fn my_game_func(a: i32) -> bool;
}
println!("{}", my_game_func(5));
let func = getfn_my_game_func();
extern "C" fn detour(a: i32) -> bool { a == 5 }
// .. hook `func` ..
let mut orig = std::ptr::null_mut();
MH_CreateHook(func as *mut c_void, detour, &mut orig as *mut _ as _);Re-exports§
pub use paste;