Move linux-specific futex code into sys module.

library/std/src/sys/unix/futex.rs

@@ -0,0 +1,38 @@
+#![cfg(any(target_os = "linux", target_os = "android"))]
+
+use crate::sync::atomic::AtomicI32;
+use crate::time::Duration;
+
+pub fn futex_wait(futex: &AtomicI32, expected: i32, timeout: Option<Duration>) {
+    let timespec;
+    let timespec_ptr = match timeout {
+        Some(timeout) => {
+            timespec = libc::timespec {
+                tv_sec: timeout.as_secs() as _,
+                tv_nsec: timeout.subsec_nanos() as _,
+            };
+            &timespec as *const libc::timespec
+        }
+        None => crate::ptr::null(),
+    };
+    unsafe {
+        libc::syscall(
+            libc::SYS_futex,
+            futex as *const AtomicI32,
+            libc::FUTEX_WAIT | libc::FUTEX_PRIVATE_FLAG,
+            expected,
+            timespec_ptr,
+        );
+    }
+}
+
+pub fn futex_wake(futex: &AtomicI32) {
+    unsafe {
+        libc::syscall(
+            libc::SYS_futex,
+            futex as *const AtomicI32,
+            libc::FUTEX_WAKE | libc::FUTEX_PRIVATE_FLAG,
+            1,
+        );
+    }
+}

library/std/src/sys/unix/mod.rs

@@ -49,6 +49,7 @@ pub mod env;
 pub mod ext;
 pub mod fd;
 pub mod fs;
+pub mod futex;
 pub mod io;
 #[cfg(target_os = "l4re")]
 mod l4re;