From 66bd7533ef19bf8a3515ce702013aba368f58df3 Mon Sep 17 00:00:00 2001
From: Alice Ryhl <aliceryhl@google.com>
Date: Wed, 3 May 2023 14:10:16 +0000
Subject: [PATCH] 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 <benno.lossin@proton.me>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Link: https://lore.kernel.org/r/20230503141016.683634-1-aliceryhl@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
rust/kernel/str.rs | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index cd3d2a6cf1fc1..c9dd3bf59e34c 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 @@ pub fn to_str(&self) -> Result<&str, core::str::Utf8Error> {
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 @@ fn deref(&self) -> &Self::Target {
}
}
+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 {
--
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