[PATCH v5 23/26] rust: str: test: replace `alloc::format`

Danilo Krummrich
2024-08-12T18:26:12Z

The current implementation of tests in str.rs use `format!` to format
strings for comparison, which, internally, creates a new `String`.

In order to prepare for getting rid of Rust's alloc crate, we have to
cut this dependency. Instead, implement `format!` for `CString`.

Note that for userspace tests, `Kmalloc`, which is backing `CString`'s
memory, is just a type alias to `Cmalloc`.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
rust/kernel/str.rs | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 209ad1bb1a49..726329530338 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -523,7 +523,28 @@ macro_rules! c_str {
#[cfg(test)]
mod tests {
use super::*;
- use alloc::format;
+
+ struct String(CString);
+
+ impl String {
+ fn from_fmt(args: fmt::Arguments<'_>) -> Self {
+ String(CString::try_from_fmt(args).unwrap())
+ }
+ }
+
+ impl Deref for String {
+ type Target = str;
+
+ fn deref(&self) -> &str {
+ self.0.to_str().unwrap()
+ }
+ }
+
+ macro_rules! format {
+ ($($f:tt)*) => ({
+ &*String::from_fmt(kernel::fmt!($($f)*))
+ })
+ }

const ALL_ASCII_CHARS: &'static str =
"\\x01\\x02\\x03\\x04\\x05\\x06\\x07\\x08\\x09\\x0a\\x0b\\x0c\\x0d\\x0e\\x0f\
--
2.45.2