ipc: Retry receiving credentials if the the message is short (#476)

ipc: Retry receiving credentials if the the message is short

rhbz#2111711 refers

lib/ipc_setup.c

@@ -473,11 +473,15 @@ qb_ipcc_us_setup_connect(struct qb_ipcc_connection *c,
 	return 0;
 }
 
+#define AUTH_RECV_MAX_RETRIES 10
+#define AUTH_RECV_SLEEP_TIME_US 100
+
 /* Called from ipcc_connect_continue() when async connect socket is active */
 int qb_ipcc_setup_connect_continue(struct qb_ipcc_connection *c, struct qb_ipc_connection_response *r)
 {
 	struct ipc_auth_data *data;
 	int32_t res;
+	int retry_count = 0;
 #ifdef QB_LINUX
 	int off = 0;
 #endif
@@ -486,8 +490,14 @@ int qb_ipcc_setup_connect_continue(struct qb_ipcc_connection *c, struct qb_ipc_c
 		qb_ipcc_us_sock_close(c->setup.u.us.sock);
 		return -ENOMEM;
 	}
-
+retry:
 	res = qb_ipc_us_recv_msghdr(data);
+	if (res == -EAGAIN && ++retry_count < AUTH_RECV_MAX_RETRIES) {
+		struct timespec ts = {0,  AUTH_RECV_SLEEP_TIME_US*QB_TIME_NS_IN_USEC};
+		struct timespec ts_left = {0, 0};
+		nanosleep(&ts, &ts_left);
+		goto retry;
+	}
 
 #ifdef QB_LINUX
 	setsockopt(c->setup.u.us.sock, SOL_SOCKET, SO_PASSCRED, &off,