Commit 6551a7fe authored Apr 03, 2023 by Miguel Ojeda

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>

parent c7e20faa

rust/kernel/error.rs

+32 −0

Original line number	Diff line number	Diff line
		@@ -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