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authorWedson Almeida Filho <wedsonaf@gmail.com>2023-04-03 12:48:15 +0300
committerMiguel Ojeda <ojeda@kernel.org>2023-04-12 19:41:04 +0300
commitef4dc4cc7001e9cce8a3b556362171648be9ad92 (patch)
tree8e0cad51c7ef0000157066084c739aa0a459a219 /rust
parent752417b3f0e7721f1d630f40da22d57e0dae043e (diff)
downloadlinux-ef4dc4cc7001e9cce8a3b556362171648be9ad92.tar.xz
rust: error: Add from_result() helper
Add a helper function to easily return C result codes from a Rust function that calls functions which return a Result<T>. Lina: Imported from rust-for-linux/rust, originally developed by Wedson as part of file_operations.rs. Added the allow() flags since there is no user in the kernel crate yet and fixed a typo in a comment. Replaced the macro with a function taking a closure, per discussion on the ML. Co-developed-by: Fox Chen <foxhlchen@gmail.com> Signed-off-by: Fox Chen <foxhlchen@gmail.com> Co-developed-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com> 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-v3-6-03779bddc02b@asahilina.net Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'rust')
-rw-r--r--rust/kernel/error.rs39
1 files changed, 39 insertions, 0 deletions
diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
index 67637b874267..5f4114b30b94 100644
--- a/rust/kernel/error.rs
+++ b/rust/kernel/error.rs
@@ -237,3 +237,42 @@ pub(crate) fn from_err_ptr<T>(ptr: *mut T) -> Result<*mut T> {
}
Ok(ptr)
}
+
+/// Calls a closure returning a [`crate::error::Result<T>`] and converts the result to
+/// a C integer result.
+///
+/// This is useful when calling Rust functions that return [`crate::error::Result<T>`]
+/// from inside `extern "C"` functions that need to return an integer error result.
+///
+/// `T` should be convertible from an `i16` via `From<i16>`.
+///
+/// # Examples
+///
+/// ```ignore
+/// # use kernel::from_result;
+/// # use kernel::bindings;
+/// unsafe extern "C" fn probe_callback(
+/// pdev: *mut bindings::platform_device,
+/// ) -> core::ffi::c_int {
+/// from_result(|| {
+/// let ptr = devm_alloc(pdev)?;
+/// bindings::platform_set_drvdata(pdev, ptr);
+/// Ok(0)
+/// })
+/// }
+/// ```
+// TODO: Remove `dead_code` marker once an in-kernel client is available.
+#[allow(dead_code)]
+pub(crate) fn from_result<T, F>(f: F) -> T
+where
+ T: From<i16>,
+ F: FnOnce() -> Result<T>,
+{
+ match f() {
+ Ok(v) => v,
+ // NO-OVERFLOW: negative `errno`s are no smaller than `-bindings::MAX_ERRNO`,
+ // `-bindings::MAX_ERRNO` fits in an `i16` as per invariant above,
+ // therefore a negative `errno` always fits in an `i16` and will not overflow.
+ Err(e) => T::from(e.to_errno() as i16),
+ }
+}