luaur_code_gen/functions/
visit_fde_entries.rs

1#[allow(non_snake_case)]
2pub unsafe fn visit_fde_entries(
3    pos: *mut core::ffi::c_char,
4    cb: unsafe extern "C" fn(*const core::ffi::c_void),
5) {
6    // C++ Luau uses a *weak* `__unw_add_dynamic_fde` symbol to detect Apple's
7    // libunwind: when it is present (Apple) each FDE entry is registered
8    // individually; when it is absent (Linux/other, which register the whole
9    // block once via `__register_frame`) the block is passed to `cb` directly.
10    // A weak extern static is a *strong* undefined reference in Rust and fails to
11    // link on Linux ("undefined symbol: __unw_add_dynamic_fde"), so detect the
12    // platform at compile time — which is exactly what the weak-symbol presence
13    // check amounted to.
14    #[cfg(not(target_vendor = "apple"))]
15    {
16        cb(pos as *const core::ffi::c_void);
17    }
18    #[cfg(target_vendor = "apple")]
19    {
20        let mut current_pos = pos;
21        loop {
22            let mut part_length: u32 = 0;
23            core::ptr::copy_nonoverlapping(
24                current_pos as *const u8,
25                &mut part_length as *mut u32 as *mut u8,
26                core::mem::size_of::<u32>(),
27            );
28
29            if part_length == 0 {
30                break;
31            }
32
33            let mut part_id: u32 = 0;
34            core::ptr::copy_nonoverlapping(
35                current_pos.add(4) as *const u8,
36                &mut part_id as *mut u32 as *mut u8,
37                core::mem::size_of::<u32>(),
38            );
39
40            if part_id != 0 {
41                cb(current_pos as *const core::ffi::c_void);
42            }
43
44            current_pos = current_pos.add(part_length as usize + 4);
45        }
46    }
47}
luaur_code_gen/functions/visit_fde_entries.rs

luaur_code_gen/functions/
visit_fde_entries.rs
