| use std::marker; |
| use std::mem; |
| use std::sync::atomic::{AtomicUsize, Ordering}; |
| |
| use libc; |
| |
| macro_rules! dlsym { |
| (fn $name:ident($($t:ty),*) -> $ret:ty) => ( |
| #[allow(bad_style)] |
| static $name: ::sys::unix::dlsym::DlSym<unsafe extern fn($($t),*) -> $ret> = |
| ::sys::unix::dlsym::DlSym { |
| name: concat!(stringify!($name), "\0"), |
| addr: ::std::sync::atomic::ATOMIC_USIZE_INIT, |
| _marker: ::std::marker::PhantomData, |
| }; |
| ) |
| } |
| |
| pub struct DlSym<F> { |
| pub name: &'static str, |
| pub addr: AtomicUsize, |
| pub _marker: marker::PhantomData<F>, |
| } |
| |
| impl<F> DlSym<F> { |
| pub fn get(&self) -> Option<&F> { |
| assert_eq!(mem::size_of::<F>(), mem::size_of::<usize>()); |
| unsafe { |
| if self.addr.load(Ordering::SeqCst) == 0 { |
| self.addr.store(fetch(self.name), Ordering::SeqCst); |
| } |
| if self.addr.load(Ordering::SeqCst) == 1 { |
| None |
| } else { |
| mem::transmute::<&AtomicUsize, Option<&F>>(&self.addr) |
| } |
| } |
| } |
| } |
| |
| unsafe fn fetch(name: &str) -> usize { |
| assert_eq!(name.as_bytes()[name.len() - 1], 0); |
| match libc::dlsym(libc::RTLD_DEFAULT, name.as_ptr() as *const _) as usize { |
| 0 => 1, |
| n => n, |
| } |
| } |