Attribute Macro relocate_fn

#[relocate_fn]

relocate_fn is a procedural macro used to generate a relocated function in Rust. It allows you to specify function relocation IDs (se_id, ae_id, and vr_id) to relocate a function at runtime. This macro generates code that attempts to resolve a function’s address based on the provided IDs, and calls the relocated function if the address is valid.

Attributes

The macro accepts the following arguments:

Attribute	Description
se_id	The ID of the Skyrim Special Edition (mandatory)
ae_id	The ID of the Skyrim Anniversary Edition (mandatory)
vr_id	The ID of the Skyrim VR (optional, defaults to se_id if not provided)

The macro generates code that will dynamically resolve the address of the function using these IDs. If the resolution is successful and the address is valid (non-null and aligned), the relocated function will be called with the same arguments as the original function. Otherwise, an error will be logged(tracing feature is required), and the program will panic.

Example

#[commonlibsse_ng_derive_internal::relocate_fn(se_id = 1, ae_id = 2, vr_id = 3)]
fn my_function(arg1: usize, arg2: usize) -> bool {
    tracing::info("arg1 = {arg1}, arg2 = {arg2}"); // We can sandwich the process before that.

    // macro is expanded from here.
    // 1. id to address
    // 2. Execute function with the argument as it is.
}

This will generate a function that attempts to resolve its address using the provided IDs and call it safely with arg1 and arg2 passed as arguments.

Notes

• The relocation IDs are used for dynamically finding the target function address.
• If no vr_id is provided, the se_id is used as the default value.
• SelfSignature: Function signature for self. like C++ decltype(T)

Panics

• The macro generates code that checks the validity of the resolved address, logging an error and panicking if invalid.