rslice: rustls_str -> str

Offer an `unsafe` route for Rust code to translate a `rustls_str` to
a `&str`.

2 files changed, 12 insertions, 7 deletions

diff --git a/src/rslice.rs b/src/rslice.rs
index c14c47e..d653cef 100644
--- a/src/rslice.rs
+++ b/src/rslice.rs
@@ -212,6 +212,15 @@ impl<'a> rustls_str<'a> {
     pub unsafe fn into_static(self) -> rustls_str<'static> {
         std::mem::transmute(self)
     }
+
+    /// Change a rustls_str back to a &str.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure the rustls_str data is valid utf8
+    pub unsafe fn to_str(&self) -> &str {
+        str::from_utf8_unchecked(slice::from_raw_parts(self.data as *const u8, self.len))
+    }
 }
 
 // If the assertion about Rust code being the only creator of rustls_str objects
@@ -247,6 +256,8 @@ fn test_rustls_str() {
         assert_eq!(*rs.data, 'a' as c_char);
         assert_eq!(*rs.data.offset(3), 'd' as c_char);
     }
+    let rs = unsafe { rs.to_str() };
+    assert_eq!(rs, s);
 }
 
 #[cfg(test)]
diff --git a/tests/rustls_version.rs b/tests/rustls_version.rs
index 446cd58..4830d3c 100644
--- a/tests/rustls_version.rs
+++ b/tests/rustls_version.rs
@@ -1,7 +1,6 @@
 use std::fs::File;
 use std::io::Read;
 use std::path::PathBuf;
-use std::{slice, str};
 
 use toml::Table;
 
@@ -51,12 +50,7 @@ fn rustls_version_match() {
     // E.g.:
     //   rustls-ffi/0.13.0/rustls/0.23.4
     let rustls_ffi_version = rustls_version();
-    let rustls_ffi_version = unsafe {
-        str::from_utf8_unchecked(slice::from_raw_parts(
-            rustls_ffi_version.data as *const u8,
-            rustls_ffi_version.len,
-        ))
-    };
+    let rustls_ffi_version = unsafe { rustls_ffi_version.to_str() };
     let rustls_ffi_version_parts = rustls_ffi_version.split('/').collect::<Vec<_>>();
     assert_eq!(
         rustls_ffi_version_parts,