Do not load the config file if the server is exiting because it failed

to start, otherwise commands like lsk which start the server again can
end up looping infinitely. Also make the first client exit
correctly. Problem reported by Wael M Nasreddine.

server-client.c

@@ -1511,7 +1511,9 @@ server_client_click_timer(__unused int fd, __unused short events, void *data)
 static void
 server_client_check_exit(struct client *c)
 {
-	if (!(c->flags & CLIENT_EXIT))
+	if (~c->flags & CLIENT_EXIT)
+		return;
+	if (c->flags & CLIENT_EXITED)
 		return;
 
 	if (EVBUFFER_LENGTH(c->stdin_data) != 0)
@@ -1524,7 +1526,7 @@ server_client_check_exit(struct client *c)
 	if (c->flags & CLIENT_ATTACHED)
 		notify_client("client-detached", c);
 	proc_send(c->peer, MSG_EXIT, -1, &c->retval, sizeof c->retval);
-	c->flags &= ~CLIENT_EXIT;
+	c->flags |= CLIENT_EXITED;
 }
 
 /* Redraw timer callback. */

server.c

@@ -44,7 +44,7 @@
 struct clients		 clients;
 
 struct tmuxproc		*server_proc;
-static int		 server_fd;
+static int		 server_fd = -1;
 static int		 server_exit;
 static struct event	 server_ev_accept;
 
@@ -208,11 +208,10 @@ server_start(struct tmuxproc *client, struct event_base *base, int lockfd,
 		cmdq_append(c, cmdq_get_error(cause));
 		free(cause);
 		c->flags |= CLIENT_EXIT;
-	}
+	} else
+		start_cfg();
 
-	start_cfg();
 	server_add_accept(0);
-
 	proc_loop(server_proc, server_loop);
 
 	job_kill_all();
@@ -364,6 +363,9 @@ server_add_accept(int timeout)
 {
 	struct timeval tv = { timeout, 0 };
 
+	if (server_fd == -1)
+		return;
+
 	if (event_initialized(&server_ev_accept))
 		event_del(&server_ev_accept);
 

tmux.h

@@ -1490,7 +1490,7 @@ struct client {
 #define CLIENT_REPEAT 0x20
 #define CLIENT_SUSPENDED 0x40
 #define CLIENT_ATTACHED 0x80
-/* 0x100 unused */
+#define CLIENT_EXITED 0x100
 #define CLIENT_DEAD 0x200
 #define CLIENT_REDRAWBORDERS 0x400
 #define CLIENT_READONLY 0x800