flopen
lockfd = flopen(group_file, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);
int flopen(const char *_path, int _flags, ...);
fd = flopen(pfh->pf_path,
lockfd = flopen(masterpasswd, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);