protocol: cleanup process without hanging

src/utils.h

@@ -25,6 +25,10 @@ get_sig_name(int sig, char *buf, size_t len);
 int
 get_sig(const char *sig_name);
 
+// waitpid with WNOHANG and return the status
+int
+wait_proc(pid_t in, pid_t *out);
+
 // Open uri with the default application of system
 int
 open_uri(char *uri);