event/ServerSocket, config/Net: abstract socket support

src/config/Net.cxx

@@ -29,6 +29,10 @@ ServerSocketAddGeneric(ServerSocket &server_socket, const char *address, unsigne
 		server_socket.AddPort(port);
 	} else if (address[0] == '/' || address[0] == '~') {
 		server_socket.AddPath(ParsePath(address));
+#ifdef __linux__
+	} else if (address[0] == '@') {
+		server_socket.AddAbstract(address);
+#endif
 	} else {
 		server_socket.AddHost(address, port);
 	}

src/event/ServerSocket.cxx

@@ -396,3 +396,19 @@ ServerSocket::AddPath(AllocatedPath &&path)
 #endif /* !HAVE_UN */
 }
 
+
+#ifdef __linux__
+
+void
+ServerSocket::AddAbstract(const char *name)
+{
+	assert(name != nullptr);
+	assert(*name == '@');
+
+	AllocatedSocketAddress address;
+	address.SetLocal(name);
+
+	AddAddress(std::move(address));
+}
+
+#endif

src/event/ServerSocket.hxx

@@ -99,6 +99,18 @@ public:
 	 */
 	void AddPath(AllocatedPath &&path);
 
+#ifdef __linux__
+	/**
+	 * Add a listener on an abstract local socket (Linux specific).
+	 *
+	 * Throws on error.
+	 *
+	 * @param name the abstract socket name, starting with a '@'
+	 * instead of a null byte
+	 */
+	void AddAbstract(const char *name);
+#endif
+
 	/**
 	 * Add a socket descriptor that is accepting connections.  After this
 	 * has been called, don't call server_socket_open(), because the