Provide a getfd function for getting the main connector file descriptor for seamless restarts

src/ckpool.c

@@ -79,6 +79,7 @@ static void *listener(void *arg)
 {
 	proc_instance_t *pi = (proc_instance_t *)arg;
 	unixsock_t *us = &pi->us;
+	ckpool_t *ckp = pi->ckp;
 	char *buf = NULL;
 	int sockd;
 
@@ -90,7 +91,7 @@ retry:
 		LOGERR("Failed to accept on socket in listener");
 		goto out;
 	}
-	/* Insert parsing and repeat code here */
+
 	buf = recv_unix_msg(sockd);
 	if (!buf) {
 		LOGWARNING("Failed to get message in listener");
@@ -101,6 +102,16 @@ retry:
 	} else if (!strncasecmp(buf, "ping", 4)) {
 		LOGDEBUG("Listener received ping request");
 		send_unix_msg(sockd, "pong");
+	} else if (!strncasecmp(buf, "getfd", 5)) {
+		char *msg;
+
+		msg = send_recv_proc(ckp->connector, "getfd");
+		if (!msg)
+			LOGWARNING("Failed to receive fd data from connector");
+		else {
+			send_unix_data(sockd, msg, sizeof(struct msghdr));
+			free(msg);
+		}
 	} else {
 		LOGINFO("Listener received unhandled message: %s", buf);
 		send_unix_msg(sockd, "unknown");

src/connector.c

@@ -430,6 +430,29 @@ static client_instance_t *client_by_id(conn_instance_t *ci, int id)
 	return client;
 }
 
+static void send_fd(int fd, int sockd)
+{
+	struct cmsghdr cmptr;
+	struct iovec iov[1];
+	struct msghdr msg;
+	char buf[2];
+
+	memset(&cmptr, 0, sizeof(struct cmsghdr));
+	iov[0].iov_base = buf;
+	iov[0].iov_len = 2;
+	msg.msg_iov = iov;
+	msg.msg_iovlen = 1;
+	msg.msg_name = NULL;
+	msg.msg_namelen = 0;
+	cmptr.cmsg_level = SOL_SOCKET;
+	cmptr.cmsg_type = SCM_RIGHTS;
+	cmptr.cmsg_len = CMSG_LEN(sizeof(int));
+	*(int *)CMSG_DATA(&cmptr) = fd;
+	buf[1] = 0;
+	buf[0] = 0;
+	send_unix_data(sockd, &msg, sizeof(struct msghdr));
+}
+
 static int connector_loop(proc_instance_t *pi, conn_instance_t *ci)
 {
 	int sockd, client_id, ret = 0, selret;
@@ -488,6 +511,10 @@ retry:
 			LOGINFO("Connector dropped client id: %d", client_id);
 		goto retry;
 	}
+	if (!strncasecmp(buf, "getfd", 5)) {
+		send_fd(ci->serverfd, sockd);
+		goto retry;
+	}
 
 	/* Anything else should be a json message to send to a client */
 	json_msg = json_loads(buf, 0, NULL);
@@ -504,6 +531,7 @@ retry:
 	realloc_strcat(&buf, "\n");
 	send_client(ci, client_id, buf);
 	json_decref(json_msg);
+	buf = NULL;
 
 	goto retry;
 out: