1 files changed, 46 insertions, 0 deletions
diff --git a/library/std/src/sys_common/thread_info.rs b/library/std/src/sys_common/thread_info.rs
new file mode 100644
index 00000000000..f09d16c33e6
--- /dev/null
+++ b/library/std/src/sys_common/thread_info.rs
@@ -0,0 +1,46 @@
+#![allow(dead_code)] // stack_guard isn't used right now on all platforms
+
+use crate::cell::RefCell;
+use crate::sys::thread::guard::Guard;
+use crate::thread::Thread;
+
+struct ThreadInfo {
+    stack_guard: Option<Guard>,
+    thread: Thread,
+}
+
+thread_local! { static THREAD_INFO: RefCell<Option<ThreadInfo>> = RefCell::new(None) }
+
+impl ThreadInfo {
+    fn with<R, F>(f: F) -> Option<R>
+    where
+        F: FnOnce(&mut ThreadInfo) -> R,
+    {
+        THREAD_INFO
+            .try_with(move |c| {
+                if c.borrow().is_none() {
+                    *c.borrow_mut() =
+                        Some(ThreadInfo { stack_guard: None, thread: Thread::new(None) })
+                }
+                f(c.borrow_mut().as_mut().unwrap())
+            })
+            .ok()
+    }
+}
+
+pub fn current_thread() -> Option<Thread> {
+    ThreadInfo::with(|info| info.thread.clone())
+}
+
+pub fn stack_guard() -> Option<Guard> {
+    ThreadInfo::with(|info| info.stack_guard.clone()).and_then(|o| o)
+}
+
+pub fn set(stack_guard: Option<Guard>, thread: Thread) {
+    THREAD_INFO.with(|c| assert!(c.borrow().is_none()));
+    THREAD_INFO.with(move |c| *c.borrow_mut() = Some(ThreadInfo { stack_guard, thread }));
+}
+
+pub fn reset_guard(stack_guard: Option<Guard>) {
+    THREAD_INFO.with(move |c| c.borrow_mut().as_mut().unwrap().stack_guard = stack_guard);
+}