F_DUP2FD_CLOEXEC
if ((oflags & O_CLOEXEC ? _fcntl(f, F_DUP2FD_CLOEXEC, wantfd) :
cmd = F_DUP2FD_CLOEXEC;
case F_DUP2FD_CLOEXEC:
if ((fd2 = fcntl(fd1, F_DUP2FD_CLOEXEC, fd1 + 1)) < 0)
if ((fd2 = fcntl(fd1, F_DUP2FD_CLOEXEC, rlp.rlim_cur + 1)) >= 0)