rust: error: Add Error::from_errno{_unchecked}()
Add a function to create `Error` values out of a kernel error return,
which safely upholds the invariant that the error code is well-formed
(negative and greater than -MAX_ERRNO). If a malformed code is passed
in, it will be converted to EINVAL.
Lina: Imported from rust-for-linux/rust as authored by Miguel and Fox
with refactoring from Wedson, renamed from_kernel_errno() to
from_errno().
Co-developed-by: Fox Chen <foxhlchen@gmail.com>
Signed-off-by: Fox Chen <foxhlchen@gmail.com>
Co-developed-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Asahi Lina <lina@asahilina.net>
Link: https://lore.kernel.org/r/20230224-rust-error-v3-3-03779bddc02b@asahilina.net
[ Mark the new associated functions as `#[allow(dead_code)]`. ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
index 154d0ca..0223d48 100644
--- a/rust/kernel/error.rs
+++ b/rust/kernel/error.rs
@@ -72,6 +72,38 @@
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
