From 6551a7fe0acbbc816802350414b37d9b42daccc8 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 3 Apr 2023 18:48:12 +0900 Subject: 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 Signed-off-by: Fox Chen Co-developed-by: Wedson Almeida Filho Signed-off-by: Wedson Almeida Filho Signed-off-by: Miguel Ojeda Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Asahi Lina 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 --- rust/kernel/error.rs | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) (limited to 'rust') diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs index 154d0ca6e2dcb..0223d48ab43dc 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 -- cgit 1.2.3-korg