5 files changed, 66 insertions, 45 deletions

diff --git a/library/std/src/os/unix/net/addr.rs b/library/std/src/os/unix/net/addr.rs
index 9757653e02c..1787eba0ef8 100644
--- a/library/std/src/os/unix/net/addr.rs
+++ b/library/std/src/os/unix/net/addr.rs
@@ -107,6 +107,16 @@ impl SocketAddr {
         addr: libc::sockaddr_un,
         mut len: libc::socklen_t,
     ) -> io::Result<SocketAddr> {
+        if cfg!(target_os = "openbsd") {
+            // on OpenBSD, getsockname(2) returns the actual size of the socket address,
+            // and not the len of the content. Figure out the length for ourselves.
+            // https://marc.info/?l=openbsd-bugs&m=170105481926736&w=2
+            let sun_path: &[u8] =
+                unsafe { mem::transmute::<&[libc::c_char], &[u8]>(&addr.sun_path) };
+            len = core::slice::memchr::memchr(0, sun_path)
+                .map_or(len, |new_len| (new_len + sun_path_offset(&addr)) as libc::socklen_t);
+        }
+
         if len == 0 {
             // When there is a datagram from unnamed unix socket
             // linux returns zero bytes of address
diff --git a/library/std/src/sys/pal/unix/thread.rs b/library/std/src/sys/pal/unix/thread.rs
index 5eb71f1f5ce..6a6bfc77a85 100644
--- a/library/std/src/sys/pal/unix/thread.rs
+++ b/library/std/src/sys/pal/unix/thread.rs
@@ -709,7 +709,7 @@ mod cgroups {
 // is created in an application with big thread-local storage requirements.
 // See #6233 for rationale and details.
 #[cfg(all(target_os = "linux", target_env = "gnu"))]
-fn min_stack_size(attr: *const libc::pthread_attr_t) -> usize {
+unsafe fn min_stack_size(attr: *const libc::pthread_attr_t) -> usize {
     // We use dlsym to avoid an ELF version dependency on GLIBC_PRIVATE. (#23628)
     // We shouldn't really be using such an internal symbol, but there's currently
     // no other way to account for the TLS size.
@@ -723,11 +723,11 @@ fn min_stack_size(attr: *const libc::pthread_attr_t) -> usize {
 
 // No point in looking up __pthread_get_minstack() on non-glibc platforms.
 #[cfg(all(not(all(target_os = "linux", target_env = "gnu")), not(target_os = "netbsd")))]
-fn min_stack_size(_: *const libc::pthread_attr_t) -> usize {
+unsafe fn min_stack_size(_: *const libc::pthread_attr_t) -> usize {
     libc::PTHREAD_STACK_MIN
 }
 
 #[cfg(target_os = "netbsd")]
-fn min_stack_size(_: *const libc::pthread_attr_t) -> usize {
+unsafe fn min_stack_size(_: *const libc::pthread_attr_t) -> usize {
     2048 // just a guess
 }
diff --git a/library/std/src/sys/sync/rwlock/queue.rs b/library/std/src/sys/sync/rwlock/queue.rs
index d1918855797..337cc6c2ca0 100644
--- a/library/std/src/sys/sync/rwlock/queue.rs
+++ b/library/std/src/sys/sync/rwlock/queue.rs
@@ -202,7 +202,7 @@ impl Node {
     fn prepare(&mut self) {
         // Fall back to creating an unnamed `Thread` handle to allow locking in
         // TLS destructors.
-        self.thread.get_or_init(|| thread::try_current().unwrap_or_else(|| Thread::new(None)));
+        self.thread.get_or_init(|| thread::try_current().unwrap_or_else(Thread::new_unnamed));
         self.completed = AtomicBool::new(false);
     }
 
diff --git a/library/std/src/thread/local.rs b/library/std/src/thread/local.rs
index fbb882e640b..c1b4440e560 100644
--- a/library/std/src/thread/local.rs
+++ b/library/std/src/thread/local.rs
@@ -53,25 +53,25 @@ use crate::fmt;
 /// # Examples
 ///
 /// ```
-/// use std::cell::RefCell;
+/// use std::cell::Cell;
 /// use std::thread;
 ///
-/// thread_local!(static FOO: RefCell<u32> = RefCell::new(1));
+/// thread_local!(static FOO: Cell<u32> = Cell::new(1));
 ///
-/// FOO.with_borrow(|v| assert_eq!(*v, 1));
-/// FOO.with_borrow_mut(|v| *v = 2);
+/// assert_eq!(FOO.get(), 1);
+/// FOO.set(2);
 ///
 /// // each thread starts out with the initial value of 1
 /// let t = thread::spawn(move|| {
-///     FOO.with_borrow(|v| assert_eq!(*v, 1));
-///     FOO.with_borrow_mut(|v| *v = 3);
+///     assert_eq!(FOO.get(), 1);
+///     FOO.set(3);
 /// });
 ///
 /// // wait for the thread to complete and bail out on panic
 /// t.join().unwrap();
 ///
 /// // we retain our original value of 2 despite the child thread
-/// FOO.with_borrow(|v| assert_eq!(*v, 2));
+/// assert_eq!(FOO.get(), 2);
 /// ```
 ///
 /// # Platform-specific behavior
@@ -141,15 +141,16 @@ impl<T: 'static> fmt::Debug for LocalKey<T> {
 /// Publicity and attributes for each static are allowed. Example:
 ///
 /// ```
-/// use std::cell::RefCell;
+/// use std::cell::{Cell, RefCell};
+///
 /// thread_local! {
-///     pub static FOO: RefCell<u32> = RefCell::new(1);
+///     pub static FOO: Cell<u32> = Cell::new(1);
 ///
-///     static BAR: RefCell<f32> = RefCell::new(1.0);
+///     static BAR: RefCell<Vec<f32>> = RefCell::new(vec![1.0, 2.0]);
 /// }
 ///
-/// FOO.with_borrow(|v| assert_eq!(*v, 1));
-/// BAR.with_borrow(|v| assert_eq!(*v, 1.0));
+/// assert_eq!(FOO.get(), 1);
+/// BAR.with_borrow(|v| assert_eq!(v[1], 2.0));
 /// ```
 ///
 /// Note that only shared references (`&T`) to the inner data may be obtained, so a
@@ -164,12 +165,13 @@ impl<T: 'static> fmt::Debug for LocalKey<T> {
 /// track any additional state.
 ///
 /// ```
-/// use std::cell::Cell;
+/// use std::cell::RefCell;
+///
 /// thread_local! {
-///     pub static FOO: Cell<u32> = const { Cell::new(1) };
+///     pub static FOO: RefCell<Vec<u32>> = const { RefCell::new(Vec::new()) };
 /// }
 ///
-/// assert_eq!(FOO.get(), 1);
+/// FOO.with_borrow(|v| assert_eq!(v.len(), 0));
 /// ```
 ///
 /// See [`LocalKey` documentation][`std::thread::LocalKey`] for more
@@ -279,10 +281,9 @@ impl<T: 'static> LocalKey<T> {
     where
         F: FnOnce(&T) -> R,
     {
-        unsafe {
-            let thread_local = (self.inner)(None).ok_or(AccessError)?;
-            Ok(f(thread_local))
-        }
+        // SAFETY: `inner` is safe to call within the lifetime of the thread
+        let thread_local = unsafe { (self.inner)(None).ok_or(AccessError)? };
+        Ok(f(thread_local))
     }
 
     /// Acquires a reference to the value in this TLS key, initializing it with
@@ -301,14 +302,17 @@ impl<T: 'static> LocalKey<T> {
     where
         F: FnOnce(Option<T>, &T) -> R,
     {
-        unsafe {
-            let mut init = Some(init);
-            let reference = (self.inner)(Some(&mut init)).expect(
+        let mut init = Some(init);
+
+        // SAFETY: `inner` is safe to call within the lifetime of the thread
+        let reference = unsafe {
+            (self.inner)(Some(&mut init)).expect(
                 "cannot access a Thread Local Storage value \
                  during or after destruction",
-            );
-            f(init, reference)
-        }
+            )
+        };
+
+        f(init, reference)
     }
 }
 
@@ -377,7 +381,7 @@ impl<T: 'static> LocalKey<Cell<T>> {
     where
         T: Copy,
     {
-        self.with(|cell| cell.get())
+        self.with(Cell::get)
     }
 
     /// Takes the contained value, leaving `Default::default()` in its place.
@@ -407,7 +411,7 @@ impl<T: 'static> LocalKey<Cell<T>> {
     where
         T: Default,
     {
-        self.with(|cell| cell.take())
+        self.with(Cell::take)
     }
 
     /// Replaces the contained value, returning the old value.
@@ -578,7 +582,7 @@ impl<T: 'static> LocalKey<RefCell<T>> {
     where
         T: Default,
     {
-        self.with(|cell| cell.take())
+        self.with(RefCell::take)
     }
 
     /// Replaces the contained value, returning the old value.
diff --git a/library/std/src/thread/mod.rs b/library/std/src/thread/mod.rs
index fd89edd4ace..604eb05040b 100644
--- a/library/std/src/thread/mod.rs
+++ b/library/std/src/thread/mod.rs
@@ -487,9 +487,11 @@ impl Builder {
             amt
         });
 
-        let my_thread = Thread::new(name.map(|name| {
-            CString::new(name).expect("thread name may not contain interior null bytes")
-        }));
+        let my_thread = name.map_or_else(Thread::new_unnamed, |name| unsafe {
+            Thread::new(
+                CString::new(name).expect("thread name may not contain interior null bytes"),
+            )
+        });
         let their_thread = my_thread.clone();
 
         let my_packet: Arc<Packet<'scope, T>> = Arc::new(Packet {
@@ -711,7 +713,7 @@ pub(crate) fn set_current(thread: Thread) {
 /// In contrast to the public `current` function, this will not panic if called
 /// from inside a TLS destructor.
 pub(crate) fn try_current() -> Option<Thread> {
-    CURRENT.try_with(|current| current.get_or_init(|| Thread::new(None)).clone()).ok()
+    CURRENT.try_with(|current| current.get_or_init(|| Thread::new_unnamed()).clone()).ok()
 }
 
 /// Gets a handle to the thread that invokes it.
@@ -1307,21 +1309,26 @@ pub struct Thread {
 }
 
 impl Thread {
-    // Used only internally to construct a thread object without spawning
-    pub(crate) fn new(name: Option<CString>) -> Thread {
-        if let Some(name) = name {
-            Self::new_inner(ThreadName::Other(name))
-        } else {
-            Self::new_inner(ThreadName::Unnamed)
-        }
+    /// Used only internally to construct a thread object without spawning.
+    ///
+    /// # Safety
+    /// `name` must be valid UTF-8.
+    pub(crate) unsafe fn new(name: CString) -> Thread {
+        unsafe { Self::new_inner(ThreadName::Other(name)) }
+    }
+
+    pub(crate) fn new_unnamed() -> Thread {
+        unsafe { Self::new_inner(ThreadName::Unnamed) }
     }
 
     // Used in runtime to construct main thread
     pub(crate) fn new_main() -> Thread {
-        Self::new_inner(ThreadName::Main)
+        unsafe { Self::new_inner(ThreadName::Main) }
     }
 
-    fn new_inner(name: ThreadName) -> Thread {
+    /// # Safety
+    /// If `name` is `ThreadName::Other(_)`, the contained string must be valid UTF-8.
+    unsafe fn new_inner(name: ThreadName) -> Thread {
         // We have to use `unsafe` here to construct the `Parker` in-place,
         // which is required for the UNIX implementation.
         //