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[v2,19/28] rust: str: add `c_str!` macro

Message ID 20221202161502.385525-20-ojeda@kernel.org
State New
Headers
Series [v2,01/28] rust: prelude: split re-exports into groups |

Commit Message

Miguel Ojeda Dec. 2, 2022, 4:14 p.m. UTC 
  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 | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)
diff mbox series

Patch

diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 3ed685cb5a3c..a995db36486f 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -321,6 +321,29 @@  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 = match $crate::str::CStr::from_bytes_with_nul(S.as_bytes()) {
+            Ok(v) => v,
+            Err(_) => panic!("string contains interior NUL"),
+        };
+        C
+    }};
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;