Merge nix-rust#1582

1582: impl Send and Sync for IoVec r=rtzoeller a=asomers



Co-authored-by: Alan Somers <[email protected]>

Author: bors[bot]

CHANGELOG.md

@@ -8,6 +8,8 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 - Added `fexecve` on DragonFly.
   (#[1577](https://github.com/nix-rust/nix/pull/1577))
+- `sys::uio::IoVec` is now `Send` and `Sync`
+  (#[1582](https://github.com/nix-rust/nix/pull/1582))
 - Added fine-grained features flags.  Most Nix functionality can now be
   conditionally enabled.  By default, all features are enabled.
   (#[1611](https://github.com/nix-rust/nix/pull/1611))

src/sys/uio.rs

@@ -228,3 +228,8 @@ impl<'a> IoVec<&'a mut [u8]> {
         }, PhantomData)
     }
 }
+
+// The only reason IoVec isn't automatically Send+Sync is because libc::iovec
+// contains raw pointers.
+unsafe impl<T> Send for IoVec<T> where T: Send {}
+unsafe impl<T> Sync for IoVec<T> where T: Sync {}