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https://github.com/torvalds/linux
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4b0c68bd0d
Add a macro to declare errors, which simplifies the work needed to add each one, avoids repetition of the code and makes it easier to change the way they are declared. Signed-off-by: Finn Behrens <me@kloenk.dev> Reviewed-by: Gary Guo <gary@garyguo.net> [Reworded, adapted for upstream and applied latest changes] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
68 lines
2.1 KiB
Rust
68 lines
2.1 KiB
Rust
// SPDX-License-Identifier: GPL-2.0
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//! Kernel errors.
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//!
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//! C header: [`include/uapi/asm-generic/errno-base.h`](../../../include/uapi/asm-generic/errno-base.h)
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use alloc::collections::TryReserveError;
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/// Contains the C-compatible error codes.
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pub mod code {
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macro_rules! declare_err {
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($err:tt $(,)? $($doc:expr),+) => {
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$(
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#[doc = $doc]
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)*
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pub const $err: super::Error = super::Error(-(crate::bindings::$err as i32));
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};
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}
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declare_err!(ENOMEM, "Out of memory.");
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}
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/// Generic integer kernel error.
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///
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/// The kernel defines a set of integer generic error codes based on C and
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/// POSIX ones. These codes may have a more specific meaning in some contexts.
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///
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/// # Invariants
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///
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/// The value is a valid `errno` (i.e. `>= -MAX_ERRNO && < 0`).
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#[derive(Clone, Copy, PartialEq, Eq)]
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pub struct Error(core::ffi::c_int);
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impl Error {
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/// Returns the kernel error code.
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pub fn to_kernel_errno(self) -> core::ffi::c_int {
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self.0
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}
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}
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impl From<TryReserveError> for Error {
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fn from(_: TryReserveError) -> Error {
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code::ENOMEM
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}
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}
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/// A [`Result`] with an [`Error`] error type.
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///
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/// To be used as the return type for functions that may fail.
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///
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/// # Error codes in C and Rust
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///
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/// In C, it is common that functions indicate success or failure through
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/// their return value; modifying or returning extra data through non-`const`
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/// pointer parameters. In particular, in the kernel, functions that may fail
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/// typically return an `int` that represents a generic error code. We model
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/// those as [`Error`].
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///
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/// In Rust, it is idiomatic to model functions that may fail as returning
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/// a [`Result`]. Since in the kernel many functions return an error code,
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/// [`Result`] is a type alias for a [`core::result::Result`] that uses
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/// [`Error`] as its error type.
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///
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/// Note that even if a function does not return anything when it succeeds,
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/// it should still be modeled as returning a `Result` rather than
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/// just an [`Error`].
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pub type Result<T = ()> = core::result::Result<T, Error>;
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