51 lines
1.4 KiB
Rust
51 lines
1.4 KiB
Rust
// dlsym.rs is taken from mio
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// https://github.com/carllerche/mio/blob/master/src/sys/unix/dlsym.rs
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use std::marker;
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use std::mem;
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use std::sync::atomic::{AtomicUsize, Ordering};
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use libc;
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macro_rules! dlsym {
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(fn $name:ident($($t:ty),*) -> $ret:ty) => (
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#[allow(bad_style)]
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static $name: $crate::dlsym::DlSym<unsafe extern fn($($t),*) -> $ret> =
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$crate::dlsym::DlSym {
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name: concat!(stringify!($name), "\0"),
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addr: ::std::sync::atomic::AtomicUsize::new(0),
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_marker: ::std::marker::PhantomData,
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};
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)
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}
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pub struct DlSym<F> {
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pub name: &'static str,
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pub addr: AtomicUsize,
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pub _marker: marker::PhantomData<F>,
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}
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impl<F> DlSym<F> {
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pub fn get(&self) -> Option<&F> {
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assert_eq!(mem::size_of::<F>(), mem::size_of::<usize>());
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unsafe {
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if self.addr.load(Ordering::SeqCst) == 0 {
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self.addr.store(fetch(self.name), Ordering::SeqCst);
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}
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if self.addr.load(Ordering::SeqCst) == 1 {
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None
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} else {
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mem::transmute::<&AtomicUsize, Option<&F>>(&self.addr)
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}
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}
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}
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}
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unsafe fn fetch(name: &str) -> usize {
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assert_eq!(name.as_bytes()[name.len() - 1], 0);
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match libc::dlsym(libc::RTLD_DEFAULT, name.as_ptr() as *const _) as usize {
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0 => 1,
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n => n,
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}
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}
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