Add sys::unix::SocketAddr::as_abstract_namespace()

Fixes tokio-rs#1517.

src/sys/unix/uds/socketaddr.rs

@@ -100,6 +100,18 @@ cfg_os_poll! {
                 None
             }
         }
+
+        /// Returns the contents of this address if it is an abstract namespace
+        /// without the leading null byte.
+        // Link to std::os::unix::net::SocketAddr pending
+        // https://github.com/rust-lang/rust/issues/85410.
+        pub fn as_abstract_namespace(&self) -> Option<&[u8]> {
+            if let AddressKind::Abstract(path) = self.address() {
+                Some(path)
+            } else {
+                None
+            }
+        }
     }
 }
 

tests/unix_listener.rs

@@ -133,6 +133,19 @@ fn unix_listener_deregister() {
     handle.join().unwrap();
 }
 
+#[cfg(target_os = "linux")]
+#[test]
+fn unix_listener_abstract_namesapce() {
+    use rand::Rng;
+    let num: u64 = rand::thread_rng().gen();
+    let name = format!("\u{0000}-mio-abstract-uds-{}", num);
+    let listener = UnixListener::bind(&name).unwrap();
+    assert_eq!(
+        listener.local_addr().unwrap().as_abstract_namespace(),
+        Some(&name.as_bytes()[1..]),
+    );
+}
+
 fn smoke_test<F>(new_listener: F, test_name: &'static str)
 where
     F: FnOnce(&Path) -> io::Result<UnixListener>,