Commit 66bd7533 authored by Alice Ryhl's avatar Alice Ryhl Committed by Miguel Ojeda
Browse files

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: default avatarBenno Lossin <benno.lossin@proton.me>
Signed-off-by: default avatarAlice Ryhl <aliceryhl@google.com>
Reviewed-by: default avatarMartin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: default avatarAndreas Hindborg <a.hindborg@samsung.com>
Link: https://lore.kernel.org/r/20230503141016.683634-1-aliceryhl@google.com


Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent 4a59081c

rust/kernel/str.rs

+22 −0
Original line number Diff line number Diff line
@@ -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 {