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authorAlice Ryhl <[email protected]>2023-05-03 14:10:16 +0000
committerMiguel Ojeda <[email protected]>2023-05-31 18:53:10 +0200
commit66bd7533ef19bf8a3515ce702013aba368f58df3 (patch)
tree01750da9020ab71d9df5eedf7e4f82a3f794a2ed
parent4a59081c09cbfe17505baf3db50ebb9b97290bae (diff)
rust: str: add conversion from `CStr` to `CString`
These methods can be used to copy the data in a temporary c string into a separate allocation, so that it can be accessed later even if the original is deallocated. The API in this change mirrors the standard library API for the `&str` and `String` types. The `ToOwned` trait is not implemented because it assumes that allocations are infallible. Reviewed-by: Benno Lossin <[email protected]> Signed-off-by: Alice Ryhl <[email protected]> Reviewed-by: Martin Rodriguez Reboredo <[email protected]> Reviewed-by: Andreas Hindborg <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Miguel Ojeda <[email protected]>
-rw-r--r--rust/kernel/str.rs22
1 files changed, 22 insertions, 0 deletions
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index cd3d2a6cf1fc..c9dd3bf59e34 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -2,6 +2,7 @@
//! String representations.
+use alloc::alloc::AllocError;
use alloc::vec::Vec;
use core::fmt::{self, Write};
use core::ops::{self, Deref, Index};
@@ -199,6 +200,12 @@ impl CStr {
pub unsafe fn as_str_unchecked(&self) -> &str {
unsafe { core::str::from_utf8_unchecked(self.as_bytes()) }
}
+
+ /// Convert this [`CStr`] into a [`CString`] by allocating memory and
+ /// copying over the string data.
+ pub fn to_cstring(&self) -> Result<CString, AllocError> {
+ CString::try_from(self)
+ }
}
impl fmt::Display for CStr {
@@ -584,6 +591,21 @@ impl Deref for CString {
}
}
+impl<'a> TryFrom<&'a CStr> for CString {
+ type Error = AllocError;
+
+ fn try_from(cstr: &'a CStr) -> Result<CString, AllocError> {
+ let mut buf = Vec::new();
+
+ buf.try_extend_from_slice(cstr.as_bytes_with_nul())
+ .map_err(|_| AllocError)?;
+
+ // INVARIANT: The `CStr` and `CString` types have the same invariants for
+ // the string data, and we copied it over without changes.
+ Ok(CString { buf })
+ }
+}
+
/// A convenience alias for [`core::format_args`].
#[macro_export]
macro_rules! fmt {