Merging upstream version 1.70.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

3 files changed, 195 insertions, 31 deletions

diff --git a/vendor/futures-util/src/lock/bilock.rs b/vendor/futures-util/src/lock/bilock.rs
index 2f51ae7c9..7ddc66ad2 100644
--- a/vendor/futures-util/src/lock/bilock.rs
+++ b/vendor/futures-util/src/lock/bilock.rs
@@ -3,11 +3,11 @@
 use alloc::boxed::Box;
 use alloc::sync::Arc;
 use core::cell::UnsafeCell;
-use core::fmt;
 use core::ops::{Deref, DerefMut};
 use core::pin::Pin;
-use core::sync::atomic::AtomicUsize;
+use core::sync::atomic::AtomicPtr;
 use core::sync::atomic::Ordering::SeqCst;
+use core::{fmt, ptr};
 #[cfg(feature = "bilock")]
 use futures_core::future::Future;
 use futures_core::task::{Context, Poll, Waker};
@@ -41,7 +41,7 @@ pub struct BiLock<T> {
 
 #[derive(Debug)]
 struct Inner<T> {
-    state: AtomicUsize,
+    state: AtomicPtr<Waker>,
     value: Option<UnsafeCell<T>>,
 }
 
@@ -61,7 +61,10 @@ impl<T> BiLock<T> {
     /// Similarly, reuniting the lock and extracting the inner value is only
     /// possible when `T` is `Unpin`.
     pub fn new(t: T) -> (Self, Self) {
-        let arc = Arc::new(Inner { state: AtomicUsize::new(0), value: Some(UnsafeCell::new(t)) });
+        let arc = Arc::new(Inner {
+            state: AtomicPtr::new(ptr::null_mut()),
+            value: Some(UnsafeCell::new(t)),
+        });
 
         (Self { arc: arc.clone() }, Self { arc })
     }
@@ -87,7 +90,8 @@ impl<T> BiLock<T> {
     pub fn poll_lock(&self, cx: &mut Context<'_>) -> Poll<BiLockGuard<'_, T>> {
         let mut waker = None;
         loop {
-            match self.arc.state.swap(1, SeqCst) {
+            let n = self.arc.state.swap(invalid_ptr(1), SeqCst);
+            match n as usize {
                 // Woohoo, we grabbed the lock!
                 0 => return Poll::Ready(BiLockGuard { bilock: self }),
 
@@ -96,8 +100,8 @@ impl<T> BiLock<T> {
 
                 // A task was previously blocked on this lock, likely our task,
                 // so we need to update that task.
-                n => unsafe {
-                    let mut prev = Box::from_raw(n as *mut Waker);
+                _ => unsafe {
+                    let mut prev = Box::from_raw(n);
                     *prev = cx.waker().clone();
                     waker = Some(prev);
                 },
@@ -105,9 +109,9 @@ impl<T> BiLock<T> {
 
             // type ascription for safety's sake!
             let me: Box<Waker> = waker.take().unwrap_or_else(|| Box::new(cx.waker().clone()));
-            let me = Box::into_raw(me) as usize;
+            let me = Box::into_raw(me);
 
-            match self.arc.state.compare_exchange(1, me, SeqCst, SeqCst) {
+            match self.arc.state.compare_exchange(invalid_ptr(1), me, SeqCst, SeqCst) {
                 // The lock is still locked, but we've now parked ourselves, so
                 // just report that we're scheduled to receive a notification.
                 Ok(_) => return Poll::Pending,
@@ -115,8 +119,8 @@ impl<T> BiLock<T> {
                 // Oops, looks like the lock was unlocked after our swap above
                 // and before the compare_exchange. Deallocate what we just
                 // allocated and go through the loop again.
-                Err(0) => unsafe {
-                    waker = Some(Box::from_raw(me as *mut Waker));
+                Err(n) if n.is_null() => unsafe {
+                    waker = Some(Box::from_raw(me));
                 },
 
                 // The top of this loop set the previous state to 1, so if we
@@ -125,7 +129,7 @@ impl<T> BiLock<T> {
                 // but we're trying to acquire the lock and there's only one
                 // other reference of the lock, so it should be impossible for
                 // that task to ever block itself.
-                Err(n) => panic!("invalid state: {}", n),
+                Err(n) => panic!("invalid state: {}", n as usize),
             }
         }
     }
@@ -164,7 +168,8 @@ impl<T> BiLock<T> {
     }
 
     fn unlock(&self) {
-        match self.arc.state.swap(0, SeqCst) {
+        let n = self.arc.state.swap(ptr::null_mut(), SeqCst);
+        match n as usize {
             // we've locked the lock, shouldn't be possible for us to see an
             // unlocked lock.
             0 => panic!("invalid unlocked state"),
@@ -174,8 +179,8 @@ impl<T> BiLock<T> {
 
             // Another task has parked themselves on this lock, let's wake them
             // up as its now their turn.
-            n => unsafe {
-                Box::from_raw(n as *mut Waker).wake();
+            _ => unsafe {
+                Box::from_raw(n).wake();
             },
         }
     }
@@ -189,7 +194,7 @@ impl<T: Unpin> Inner<T> {
 
 impl<T> Drop for Inner<T> {
     fn drop(&mut self) {
-        assert_eq!(self.state.load(SeqCst), 0);
+        assert!(self.state.load(SeqCst).is_null());
     }
 }
 
@@ -224,6 +229,9 @@ pub struct BiLockGuard<'a, T> {
     bilock: &'a BiLock<T>,
 }
 
+// We allow parallel access to T via Deref, so Sync bound is also needed here.
+unsafe impl<T: Send + Sync> Sync for BiLockGuard<'_, T> {}
+
 impl<T> Deref for BiLockGuard<'_, T> {
     type Target = T;
     fn deref(&self) -> &T {
@@ -274,3 +282,12 @@ impl<'a, T> Future for BiLockAcquire<'a, T> {
         self.bilock.poll_lock(cx)
     }
 }
+
+// Based on core::ptr::invalid_mut. Equivalent to `addr as *mut T`, but is strict-provenance compatible.
+#[allow(clippy::useless_transmute)]
+#[inline]
+fn invalid_ptr<T>(addr: usize) -> *mut T {
+    // SAFETY: every valid integer is also a valid pointer (as long as you don't dereference that
+    // pointer).
+    unsafe { core::mem::transmute(addr) }
+}
diff --git a/vendor/futures-util/src/lock/mod.rs b/vendor/futures-util/src/lock/mod.rs
index cf374c016..0be72717c 100644
--- a/vendor/futures-util/src/lock/mod.rs
+++ b/vendor/futures-util/src/lock/mod.rs
@@ -4,11 +4,18 @@
 //! library is activated, and it is activated by default.
 
 #[cfg(not(futures_no_atomic_cas))]
-#[cfg(feature = "std")]
-mod mutex;
+#[cfg(any(feature = "sink", feature = "io"))]
+#[cfg(not(feature = "bilock"))]
+pub(crate) use self::bilock::BiLock;
+#[cfg(not(futures_no_atomic_cas))]
+#[cfg(feature = "bilock")]
+#[cfg_attr(docsrs, doc(cfg(feature = "bilock")))]
+pub use self::bilock::{BiLock, BiLockAcquire, BiLockGuard, ReuniteError};
 #[cfg(not(futures_no_atomic_cas))]
 #[cfg(feature = "std")]
-pub use self::mutex::{MappedMutexGuard, Mutex, MutexGuard, MutexLockFuture};
+pub use self::mutex::{
+    MappedMutexGuard, Mutex, MutexGuard, MutexLockFuture, OwnedMutexGuard, OwnedMutexLockFuture,
+};
 
 #[cfg(not(futures_no_atomic_cas))]
 #[cfg(any(feature = "bilock", feature = "sink", feature = "io"))]
@@ -16,10 +23,5 @@ pub use self::mutex::{MappedMutexGuard, Mutex, MutexGuard, MutexLockFuture};
 #[cfg_attr(not(feature = "bilock"), allow(unreachable_pub))]
 mod bilock;
 #[cfg(not(futures_no_atomic_cas))]
-#[cfg(any(feature = "sink", feature = "io"))]
-#[cfg(not(feature = "bilock"))]
-pub(crate) use self::bilock::BiLock;
-#[cfg(not(futures_no_atomic_cas))]
-#[cfg(feature = "bilock")]
-#[cfg_attr(docsrs, doc(cfg(feature = "bilock")))]
-pub use self::bilock::{BiLock, BiLockAcquire, BiLockGuard, ReuniteError};
+#[cfg(feature = "std")]
+mod mutex;
diff --git a/vendor/futures-util/src/lock/mutex.rs b/vendor/futures-util/src/lock/mutex.rs
index 85dcb1537..335ad1427 100644
--- a/vendor/futures-util/src/lock/mutex.rs
+++ b/vendor/futures-util/src/lock/mutex.rs
@@ -1,14 +1,16 @@
-use futures_core::future::{FusedFuture, Future};
-use futures_core::task::{Context, Poll, Waker};
-use slab::Slab;
 use std::cell::UnsafeCell;
 use std::marker::PhantomData;
 use std::ops::{Deref, DerefMut};
 use std::pin::Pin;
 use std::sync::atomic::{AtomicUsize, Ordering};
-use std::sync::Mutex as StdMutex;
+use std::sync::{Arc, Mutex as StdMutex};
 use std::{fmt, mem};
 
+use slab::Slab;
+
+use futures_core::future::{FusedFuture, Future};
+use futures_core::task::{Context, Poll, Waker};
+
 /// A futures-aware mutex.
 ///
 /// # Fairness
@@ -107,6 +109,18 @@ impl<T: ?Sized> Mutex<T> {
         }
     }
 
+    /// Attempt to acquire the lock immediately.
+    ///
+    /// If the lock is currently held, this will return `None`.
+    pub fn try_lock_owned(self: &Arc<Self>) -> Option<OwnedMutexGuard<T>> {
+        let old_state = self.state.fetch_or(IS_LOCKED, Ordering::Acquire);
+        if (old_state & IS_LOCKED) == 0 {
+            Some(OwnedMutexGuard { mutex: self.clone() })
+        } else {
+            None
+        }
+    }
+
     /// Acquire the lock asynchronously.
     ///
     /// This method returns a future that will resolve once the lock has been
@@ -115,6 +129,14 @@ impl<T: ?Sized> Mutex<T> {
         MutexLockFuture { mutex: Some(self), wait_key: WAIT_KEY_NONE }
     }
 
+    /// Acquire the lock asynchronously.
+    ///
+    /// This method returns a future that will resolve once the lock has been
+    /// successfully acquired.
+    pub fn lock_owned(self: Arc<Self>) -> OwnedMutexLockFuture<T> {
+        OwnedMutexLockFuture { mutex: Some(self), wait_key: WAIT_KEY_NONE }
+    }
+
     /// Returns a mutable reference to the underlying data.
     ///
     /// Since this call borrows the `Mutex` mutably, no actual locking needs to
@@ -173,7 +195,118 @@ impl<T: ?Sized> Mutex<T> {
 }
 
 // Sentinel for when no slot in the `Slab` has been dedicated to this object.
-const WAIT_KEY_NONE: usize = usize::max_value();
+const WAIT_KEY_NONE: usize = usize::MAX;
+
+/// A future which resolves when the target mutex has been successfully acquired, owned version.
+pub struct OwnedMutexLockFuture<T: ?Sized> {
+    // `None` indicates that the mutex was successfully acquired.
+    mutex: Option<Arc<Mutex<T>>>,
+    wait_key: usize,
+}
+
+impl<T: ?Sized> fmt::Debug for OwnedMutexLockFuture<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("OwnedMutexLockFuture")
+            .field("was_acquired", &self.mutex.is_none())
+            .field("mutex", &self.mutex)
+            .field(
+                "wait_key",
+                &(if self.wait_key == WAIT_KEY_NONE { None } else { Some(self.wait_key) }),
+            )
+            .finish()
+    }
+}
+
+impl<T: ?Sized> FusedFuture for OwnedMutexLockFuture<T> {
+    fn is_terminated(&self) -> bool {
+        self.mutex.is_none()
+    }
+}
+
+impl<T: ?Sized> Future for OwnedMutexLockFuture<T> {
+    type Output = OwnedMutexGuard<T>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let this = self.get_mut();
+
+        let mutex = this.mutex.as_ref().expect("polled OwnedMutexLockFuture after completion");
+
+        if let Some(lock) = mutex.try_lock_owned() {
+            mutex.remove_waker(this.wait_key, false);
+            this.mutex = None;
+            return Poll::Ready(lock);
+        }
+
+        {
+            let mut waiters = mutex.waiters.lock().unwrap();
+            if this.wait_key == WAIT_KEY_NONE {
+                this.wait_key = waiters.insert(Waiter::Waiting(cx.waker().clone()));
+                if waiters.len() == 1 {
+                    mutex.state.fetch_or(HAS_WAITERS, Ordering::Relaxed); // released by mutex unlock
+                }
+            } else {
+                waiters[this.wait_key].register(cx.waker());
+            }
+        }
+
+        // Ensure that we haven't raced `MutexGuard::drop`'s unlock path by
+        // attempting to acquire the lock again.
+        if let Some(lock) = mutex.try_lock_owned() {
+            mutex.remove_waker(this.wait_key, false);
+            this.mutex = None;
+            return Poll::Ready(lock);
+        }
+
+        Poll::Pending
+    }
+}
+
+impl<T: ?Sized> Drop for OwnedMutexLockFuture<T> {
+    fn drop(&mut self) {
+        if let Some(mutex) = self.mutex.as_ref() {
+            // This future was dropped before it acquired the mutex.
+            //
+            // Remove ourselves from the map, waking up another waiter if we
+            // had been awoken to acquire the lock.
+            mutex.remove_waker(self.wait_key, true);
+        }
+    }
+}
+
+/// An RAII guard returned by the `lock_owned` and `try_lock_owned` methods.
+/// When this structure is dropped (falls out of scope), the lock will be
+/// unlocked.
+pub struct OwnedMutexGuard<T: ?Sized> {
+    mutex: Arc<Mutex<T>>,
+}
+
+impl<T: ?Sized + fmt::Debug> fmt::Debug for OwnedMutexGuard<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("OwnedMutexGuard")
+            .field("value", &&**self)
+            .field("mutex", &self.mutex)
+            .finish()
+    }
+}
+
+impl<T: ?Sized> Drop for OwnedMutexGuard<T> {
+    fn drop(&mut self) {
+        self.mutex.unlock()
+    }
+}
+
+impl<T: ?Sized> Deref for OwnedMutexGuard<T> {
+    type Target = T;
+    fn deref(&self) -> &T {
+        unsafe { &*self.mutex.value.get() }
+    }
+}
+
+impl<T: ?Sized> DerefMut for OwnedMutexGuard<T> {
+    fn deref_mut(&mut self) -> &mut T {
+        unsafe { &mut *self.mutex.value.get() }
+    }
+}
 
 /// A future which resolves when the target mutex has been successfully acquired.
 pub struct MutexLockFuture<'a, T: ?Sized> {
@@ -386,13 +519,25 @@ unsafe impl<T: ?Sized + Send> Sync for Mutex<T> {}
 // It's safe to switch which thread the acquire is being attempted on so long as
 // `T` can be accessed on that thread.
 unsafe impl<T: ?Sized + Send> Send for MutexLockFuture<'_, T> {}
+
 // doesn't have any interesting `&self` methods (only Debug)
 unsafe impl<T: ?Sized> Sync for MutexLockFuture<'_, T> {}
 
+// It's safe to switch which thread the acquire is being attempted on so long as
+// `T` can be accessed on that thread.
+unsafe impl<T: ?Sized + Send> Send for OwnedMutexLockFuture<T> {}
+
+// doesn't have any interesting `&self` methods (only Debug)
+unsafe impl<T: ?Sized> Sync for OwnedMutexLockFuture<T> {}
+
 // Safe to send since we don't track any thread-specific details-- the inner
 // lock is essentially spinlock-equivalent (attempt to flip an atomic bool)
 unsafe impl<T: ?Sized + Send> Send for MutexGuard<'_, T> {}
 unsafe impl<T: ?Sized + Sync> Sync for MutexGuard<'_, T> {}
+
+unsafe impl<T: ?Sized + Send> Send for OwnedMutexGuard<T> {}
+unsafe impl<T: ?Sized + Sync> Sync for OwnedMutexGuard<T> {}
+
 unsafe impl<T: ?Sized + Send, U: ?Sized + Send> Send for MappedMutexGuard<'_, T, U> {}
 unsafe impl<T: ?Sized + Sync, U: ?Sized + Sync> Sync for MappedMutexGuard<'_, T, U> {}