cstr16: add method to get the underlying bytes

Author: phip1611

CHANGELOG.md

@@ -20,6 +20,9 @@
   - `From<&CStr16>` for `String`
   - `From<&CString16>` for `String`
 - Added `RuntimeServices::get_variable_boxed` (requires the `alloc` feature).
+- Added `CStr16::to_bytes` and `CStr16::to_bytes_with_nul` as well as
+  `AsRef<[u8]>` and `Borrow<[u8]>` for `CStr16`.
+- Added `AsRef<[u8]>` and `Borrow<[u8]>` for `CStr16`.
 
 ### Changed
 

uefi/src/data_types/strs.rs

@@ -1,6 +1,7 @@
 use super::chars::{Char16, Char8, NUL_16, NUL_8};
 use super::UnalignedSlice;
 use crate::polyfill::maybe_uninit_slice_assume_init_ref;
+use core::borrow::Borrow;
 use core::ffi::CStr;
 use core::iter::Iterator;
 use core::mem::MaybeUninit;
@@ -147,6 +148,18 @@ impl fmt::Display for CStr8 {
     }
 }
 
+impl AsRef<[u8]> for CStr8 {
+    fn as_ref(&self) -> &[u8] {
+        self.to_bytes_with_nul()
+    }
+}
+
+impl Borrow<[u8]> for CStr8 {
+    fn borrow(&self) -> &[u8] {
+        self.to_bytes_with_nul()
+    }
+}
+
 impl<StrType: AsRef<str> + ?Sized> EqStrUntilNul<StrType> for CStr8 {
     fn eq_str_until_nul(&self, other: &StrType) -> bool {
         let other = other.as_ref();
@@ -389,6 +402,32 @@ impl CStr16 {
         }
         Ok(())
     }
+
+    /// Like [`to_bytes_with_nul`] but without the terminating null character.
+    #[must_use]
+    pub fn to_bytes(&self) -> &[u8] {
+        let slice = self.to_bytes_with_nul();
+        &slice[..slice.len() - 1]
+    }
+
+    /// Returns the underlying bytes as slice including the terminating null
+    /// character.
+    #[must_use]
+    pub fn to_bytes_with_nul(&self) -> &[u8] {
+        unsafe { &*(slice::from_raw_parts(self.0.as_ptr().cast(), self.num_bytes())) }
+    }
+}
+
+impl AsRef<[u8]> for CStr16 {
+    fn as_ref(&self) -> &[u8] {
+        self.to_bytes_with_nul()
+    }
+}
+
+impl Borrow<[u8]> for CStr16 {
+    fn borrow(&self) -> &[u8] {
+        self.to_bytes_with_nul()
+    }
 }
 
 #[cfg(feature = "alloc")]
@@ -615,6 +654,7 @@ mod tests {
             string.as_slice_with_nul(),
             &[Char16::try_from('a').unwrap(), NUL_16]
         );
+        assert_eq!(string.to_bytes(), &[b'a', 0, 0, 0])
     }
 
     // Code generation helper for the compare tests of our CStrX types against "str" and "String"