1 files changed, 53 insertions, 0 deletions
diff --git a/rust/kernel/safety.rs b/rust/kernel/safety.rs
new file mode 100644
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--- /dev/null
+++ b/rust/kernel/safety.rs
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Safety related APIs.
+
+/// Checks that a precondition of an unsafe function is followed.
+///
+/// The check is enabled at runtime if debug assertions (`CONFIG_RUST_DEBUG_ASSERTIONS`)
+/// are enabled. Otherwise, this macro is a no-op.
+///
+/// # Examples
+///
+/// ```no_run
+/// use kernel::unsafe_precondition_assert;
+///
+/// struct RawBuffer<T: Copy, const N: usize> {
+///     data: [T; N],
+/// }
+///
+/// impl<T: Copy, const N: usize> RawBuffer<T, N> {
+///     /// # Safety
+///     ///
+///     /// The caller must ensure that `index` is less than `N`.
+///     unsafe fn set_unchecked(&mut self, index: usize, value: T) {
+///         unsafe_precondition_assert!(
+///             index < N,
+///             "RawBuffer::set_unchecked() requires index ({index}) < N ({N})"
+///         );
+///
+///         // SAFETY: By the safety requirements of this function, `index` is valid.
+///         unsafe {
+///             *self.data.get_unchecked_mut(index) = value;
+///         }
+///     }
+/// }
+/// ```
+///
+/// # Panics
+///
+/// Panics if the expression is evaluated to [`false`] at runtime.
+#[macro_export]
+macro_rules! unsafe_precondition_assert {
+    ($cond:expr $(,)?) => {
+        $crate::unsafe_precondition_assert!(@inner $cond, ::core::stringify!($cond))
+    };
+
+    ($cond:expr, $($arg:tt)+) => {
+        $crate::unsafe_precondition_assert!(@inner $cond, $crate::prelude::fmt!($($arg)+))
+    };
+
+    (@inner $cond:expr, $msg:expr) => {
+        ::core::debug_assert!($cond, "unsafe precondition violated: {}", $msg)
+    };
+}