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#![allow(dead_code, unused_macros)]
use crate::ffi::CStr;
use crate::marker;
use crate::mem;
use crate::sync::atomic::{self, AtomicUsize, Ordering};
macro_rules! weak {
(fn $name:ident($($t:ty),*) -> $ret:ty) => (
static $name: crate::sys::weak::Weak<unsafe extern "C" fn($($t),*) -> $ret> =
crate::sys::weak::Weak::new(concat!(stringify!($name), '\0'));
)
}
pub struct Weak<F> {
name: &'static str,
addr: AtomicUsize,
_marker: marker::PhantomData<F>,
}
impl<F> Weak<F> {
pub const fn new(name: &'static str) -> Weak<F> {
Weak { name, addr: AtomicUsize::new(1), _marker: marker::PhantomData }
}
pub fn get(&self) -> Option<F> {
assert_eq!(mem::size_of::<F>(), mem::size_of::<usize>());
unsafe {
match self.addr.load(Ordering::Relaxed) {
1 => self.initialize(),
0 => None,
addr => {
let func = mem::transmute_copy::<usize, F>(&addr);
atomic::fence(Ordering::Acquire);
Some(func)
}
}
}
}
#[cold]
unsafe fn initialize(&self) -> Option<F> {
let val = fetch(self.name);
self.addr.store(val, Ordering::Release);
match val {
0 => None,
addr => Some(mem::transmute_copy::<usize, F>(&addr)),
}
}
}
unsafe fn fetch(name: &str) -> usize {
let name = match CStr::from_bytes_with_nul(name.as_bytes()) {
Ok(cstr) => cstr,
Err(..) => return 0,
};
libc::dlsym(libc::RTLD_DEFAULT, name.as_ptr()) as usize
}
#[cfg(not(any(target_os = "linux", target_os = "android")))]
macro_rules! syscall {
(fn $name:ident($($arg_name:ident: $t:ty),*) -> $ret:ty) => (
unsafe fn $name($($arg_name: $t),*) -> $ret {
use super::os;
weak! { fn $name($($t),*) -> $ret }
if let Some(fun) = $name.get() {
fun($($arg_name),*)
} else {
os::set_errno(libc::ENOSYS);
-1
}
}
)
}
#[cfg(any(target_os = "linux", target_os = "android"))]
macro_rules! syscall {
(fn $name:ident($($arg_name:ident: $t:ty),*) -> $ret:ty) => (
unsafe fn $name($($arg_name:$t),*) -> $ret {
use libc::*;
weak! { fn $name($($t),*) -> $ret }
if let Some(fun) = $name.get() {
fun($($arg_name),*)
} else {
syscall(
concat_idents!(SYS_, $name),
$($arg_name),*
) as $ret
}
}
)
}