// SPDX-License-Identifier: GPL-2.0 //! Kernel errors.//!//! C header: [`include/uapi/asm-generic/errno-base.h`](../../../include/uapi/asm-generic/errno-base.h) use alloc::{    alloc::{AllocError, LayoutError},    collections::TryReserveError,}; use core::convert::From;use core::num::TryFromIntError;use core::str::Utf8Error; /// Contains the C-compatible error codes.pub mod code {    macro_rules! declare_err {        ($err:tt $(,)? $($doc:expr),+) => {            $(            #[doc = $doc]            )*            pub const $err: super::Error = super::Error(-(crate::bindings::$err as i32));        };    }     declare_err!(EPERM, "Operation not permitted.");    declare_err!(ENOENT, "No such file or directory.");    declare_err!(ESRCH, "No such process.");    declare_err!(EINTR, "Interrupted system call.");    declare_err!(EIO, "I/O error.");    declare_err!(ENXIO, "No such device or address.");    declare_err!(E2BIG, "Argument list too long.");    declare_err!(ENOEXEC, "Exec format error.");    declare_err!(EBADF, "Bad file number.");    declare_err!(ECHILD, "Exec format error.");    declare_err!(EAGAIN, "Try again.");    declare_err!(ENOMEM, "Out of memory.");    declare_err!(EACCES, "Permission denied.");    declare_err!(EFAULT, "Bad address.");    declare_err!(ENOTBLK, "Block device required.");    declare_err!(EBUSY, "Device or resource busy.");    declare_err!(EEXIST, "File exists.");    declare_err!(EXDEV, "Cross-device link.");    declare_err!(ENODEV, "No such device.");    declare_err!(ENOTDIR, "Not a directory.");    declare_err!(EISDIR, "Is a directory.");    declare_err!(EINVAL, "Invalid argument.");    declare_err!(ENFILE, "File table overflow.");    declare_err!(EMFILE, "Too many open files.");    declare_err!(ENOTTY, "Not a typewriter.");    declare_err!(ETXTBSY, "Text file busy.");    declare_err!(EFBIG, "File too large.");    declare_err!(ENOSPC, "No space left on device.");    declare_err!(ESPIPE, "Illegal seek.");    declare_err!(EROFS, "Read-only file system.");    declare_err!(EMLINK, "Too many links.");    declare_err!(EPIPE, "Broken pipe.");    declare_err!(EDOM, "Math argument out of domain of func.");    declare_err!(ERANGE, "Math result not representable.");} /// Generic integer kernel error.////// The kernel defines a set of integer generic error codes based on C and/// POSIX ones. These codes may have a more specific meaning in some contexts.////// # Invariants////// The value is a valid `errno` (i.e. `>= -MAX_ERRNO && < 0`).#[derive(Clone, Copy, PartialEq, Eq)]pub struct Error(core::ffi::c_int); impl Error {    /// Returns the kernel error code.    pub fn to_kernel_errno(self) -> core::ffi::c_int {        self.0    }} impl From<AllocError> for Error {    fn from(_: AllocError) -> Error {        code::ENOMEM    }} impl From<TryFromIntError> for Error {    fn from(_: TryFromIntError) -> Error {        code::EINVAL    }} impl From<Utf8Error> for Error {    fn from(_: Utf8Error) -> Error {        code::EINVAL    }} impl From<TryReserveError> for Error {    fn from(_: TryReserveError) -> Error {        code::ENOMEM    }} impl From<LayoutError> for Error {    fn from(_: LayoutError) -> Error {        code::ENOMEM    }} impl From<core::fmt::Error> for Error {    fn from(_: core::fmt::Error) -> Error {        code::EINVAL    }} impl From<core::convert::Infallible> for Error {    fn from(e: core::convert::Infallible) -> Error {        match e {}    }} /// A [`Result`] with an [`Error`] error type.////// To be used as the return type for functions that may fail.////// # Error codes in C and Rust////// In C, it is common that functions indicate success or failure through/// their return value; modifying or returning extra data through non-`const`/// pointer parameters. In particular, in the kernel, functions that may fail/// typically return an `int` that represents a generic error code. We model/// those as [`Error`].////// In Rust, it is idiomatic to model functions that may fail as returning/// a [`Result`]. Since in the kernel many functions return an error code,/// [`Result`] is a type alias for a [`core::result::Result`] that uses/// [`Error`] as its error type.////// Note that even if a function does not return anything when it succeeds,/// it should still be modeled as returning a `Result` rather than/// just an [`Error`].pub type Result<T = ()> = core::result::Result<T, Error>;