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Subject[PATCH v1 19/28] rust: str: add `c_str!` macro
Date
From: Gary Guo <gary@garyguo.net>

Add `c_str!`, which is a convenience macro that creates a new `CStr`
from a string literal.

It is designed to be similar to a `str` in usage, and it is usable
in const contexts, for instance:

const X: &CStr = c_str!("Example");

Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com>
Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com>
Signed-off-by: Gary Guo <gary@garyguo.net>
[Reworded, adapted for upstream and applied latest changes]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
rust/kernel/str.rs | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)

diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 3ed685cb5a3c..3fb73b888dce 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -128,6 +128,18 @@ impl CStr {
Ok(unsafe { Self::from_bytes_with_nul_unchecked(bytes) })
}

+ /// Creates a [`CStr`] from a `[u8]`, panic if input is not valid.
+ ///
+ /// This function is only meant to be used by `c_str!` macro, so
+ /// crates using `c_str!` macro don't have to enable `const_panic` feature.
+ #[doc(hidden)]
+ pub const fn from_bytes_with_nul_unwrap(bytes: &[u8]) -> &Self {
+ match Self::from_bytes_with_nul(bytes) {
+ Ok(v) => v,
+ Err(_) => panic!("string contains interior NUL"),
+ }
+ }
+
/// Creates a [`CStr`] from a `[u8]` without performing any additional
/// checks.
///
@@ -321,6 +333,26 @@ where
}
}

+/// Creates a new [`CStr`] from a string literal.
+///
+/// The string literal should not contain any `NUL` bytes.
+///
+/// # Examples
+///
+/// ```
+/// # use kernel::c_str;
+/// # use kernel::str::CStr;
+/// const MY_CSTR: &CStr = c_str!("My awesome CStr!");
+/// ```
+#[macro_export]
+macro_rules! c_str {
+ ($str:expr) => {{
+ const S: &str = concat!($str, "\0");
+ const C: &$crate::str::CStr = $crate::str::CStr::from_bytes_with_nul_unwrap(S.as_bytes());
+ C
+ }};
+}
+
#[cfg(test)]
mod tests {
use super::*;
--
2.38.1
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