1 files changed, 32 insertions, 0 deletions
diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
index 154d0ca6e2dc..0223d48ab43d 100644
--- a/rust/kernel/error.rs
+++ b/rust/kernel/error.rs
@@ -72,6 +72,38 @@ pub mod code {
 pub struct Error(core::ffi::c_int);
 
 impl Error {
+    /// Creates an [`Error`] from a kernel error code.
+    ///
+    /// It is a bug to pass an out-of-range `errno`. `EINVAL` would
+    /// be returned in such a case.
+    #[allow(dead_code)]
+    pub(crate) fn from_errno(errno: core::ffi::c_int) -> Error {
+        if errno < -(bindings::MAX_ERRNO as i32) || errno >= 0 {
+            // TODO: Make it a `WARN_ONCE` once available.
+            crate::pr_warn!(
+                "attempted to create `Error` with out of range `errno`: {}",
+                errno
+            );
+            return code::EINVAL;
+        }
+
+        // INVARIANT: The check above ensures the type invariant
+        // will hold.
+        Error(errno)
+    }
+
+    /// Creates an [`Error`] from a kernel error code.
+    ///
+    /// # Safety
+    ///
+    /// `errno` must be within error code range (i.e. `>= -MAX_ERRNO && < 0`).
+    #[allow(dead_code)]
+    unsafe fn from_errno_unchecked(errno: core::ffi::c_int) -> Error {
+        // INVARIANT: The contract ensures the type invariant
+        // will hold.
+        Error(errno)
+    }
+
     /// Returns the kernel error code.
     pub fn to_errno(self) -> core::ffi::c_int {
         self.0