From: Gary Guo Date: Tue, 3 Feb 2026 13:06:27 +0000 (+0000) Subject: rust: disallow use of `CStr::as_ptr` and `CStr::from_ptr` X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=b3d161f22ba9b2dc16bb82aa2b8515d98c99624f;p=thirdparty%2Fkernel%2Flinux.git rust: disallow use of `CStr::as_ptr` and `CStr::from_ptr` As kernel always use unsigned char and not the platform ABI's default, an user should always use `as_char_ptr` provided via `CStrExt` instead. Therefore configure `disallow-methods` feature of clippy to catch incorrect usage. Similarly, the dual `from_ptr` is also disallowed. [ As an example, without the previous commit, we would get a warning like: warning: use of a disallowed method `core::ffi::CStr::as_ptr` --> rust/kernel/task.rs:422:54 | 422 | unsafe { crate::bindings::__might_sleep(file.as_ptr().cast(), loc.line() as i32) } | ^^^^^^ help: kernel's `char` is always unsigned, use `as_char_ptr` instead: `kernel::prelude::CStrExt::as_char_ptr` | = help: for further information visit https://rust-lang.github.io/rust-clippy/rust-1.94.0/index.html#disallowed_methods = note: `-W clippy::disallowed-methods` implied by `-W clippy::all` = help: to override `-W clippy::all` add `#[allow(clippy::disallowed_methods)]` - Miguel ] Signed-off-by: Gary Guo Reviewed-by: Tamir Duberstein Link: https://patch.msgid.link/20260203130745.868762-2-gary@kernel.org Signed-off-by: Miguel Ojeda --- diff --git a/.clippy.toml b/.clippy.toml index 137f41d203de..a51de9a46380 100644 --- a/.clippy.toml +++ b/.clippy.toml @@ -9,3 +9,13 @@ disallowed-macros = [ # it here, see: https://github.com/rust-lang/rust-clippy/issues/11303. { path = "kernel::dbg", reason = "the `dbg!` macro is intended as a debugging tool", allow-invalid = true }, ] + +[[disallowed-methods]] +path = "core::ffi::CStr::as_ptr" +replacement = "kernel::prelude::CStrExt::as_char_ptr" +reason = "kernel's `char` is always unsigned, use `as_char_ptr` instead" + +[[disallowed-methods]] +path = "core::ffi::CStr::from_ptr" +replacement = "kernel::prelude::CStrExt::from_char_ptr" +reason = "kernel's `char` is always unsigned, use `from_char_ptr` instead" diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs index fa87779d2253..97bf9427af59 100644 --- a/rust/kernel/str.rs +++ b/rust/kernel/str.rs @@ -189,6 +189,7 @@ macro_rules! b_str { // // - error[E0379]: functions in trait impls cannot be declared const #[inline] +#[expect(clippy::disallowed_methods, reason = "internal implementation")] pub const fn as_char_ptr_in_const_context(c_str: &CStr) -> *const c_char { c_str.as_ptr().cast() } @@ -319,6 +320,7 @@ unsafe fn to_bytes_mut(s: &mut CStr) -> &mut [u8] { impl CStrExt for CStr { #[inline] + #[expect(clippy::disallowed_methods, reason = "internal implementation")] unsafe fn from_char_ptr<'a>(ptr: *const c_char) -> &'a Self { // SAFETY: The safety preconditions are the same as for `CStr::from_ptr`. unsafe { CStr::from_ptr(ptr.cast()) } @@ -334,6 +336,7 @@ impl CStrExt for CStr { } #[inline] + #[expect(clippy::disallowed_methods, reason = "internal implementation")] fn as_char_ptr(&self) -> *const c_char { self.as_ptr().cast() }