From b80fa76ee0a160fffa04e337b8e33ef655a80649 Mon Sep 17 00:00:00 2001 From: Josh Stone Date: Fri, 20 Mar 2020 15:42:56 -0700 Subject: Implement ToOwned::clone_into for CStr It can try to keep its allocation by converting the inner `Box` to `Vec`, using `clone_into` on the bytes, then convert back to `Box`. --- src/libstd/ffi/c_str.rs | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'src/libstd') diff --git a/src/libstd/ffi/c_str.rs b/src/libstd/ffi/c_str.rs index 04eaba515ff..0a4802fb2c8 100644 --- a/src/libstd/ffi/c_str.rs +++ b/src/libstd/ffi/c_str.rs @@ -1329,6 +1329,12 @@ impl ToOwned for CStr { fn to_owned(&self) -> CString { CString { inner: self.to_bytes_with_nul().into() } } + + fn clone_into(&self, target: &mut CString) { + let mut b = Vec::from(mem::take(&mut target.inner)); + self.to_bytes_with_nul().clone_into(&mut b); + target.inner = b.into_boxed_slice(); + } } #[stable(feature = "cstring_asref", since = "1.7.0")] @@ -1510,6 +1516,17 @@ mod tests { assert_eq!(boxed.to_bytes_with_nul(), &[0]); } + #[test] + fn test_c_str_clone_into() { + let mut c_string = CString::new("lorem").unwrap(); + let c_ptr = c_string.as_ptr(); + let c_str = CStr::from_bytes_with_nul(b"ipsum\0").unwrap(); + c_str.clone_into(&mut c_string); + assert_eq!(c_str, c_string.as_c_str()); + // The exact same size shouldn't have needed to move its allocation + assert_eq!(c_ptr, c_string.as_ptr()); + } + #[test] fn into_rc() { let orig: &[u8] = b"Hello, world!\0"; -- cgit 1.4.1-3-g733a5