// descriptors.
func forkExecPipe(p []int) error {
	err := Pipe(p)
	if err != nil {
		return err
	}
	_, err = fcntl(p[0], F_SETFD, FD_CLOEXEC)
	if err != nil {
		return err
	}
	_, err = fcntl(p[1], F_SETFD, FD_CLOEXEC)
	return err
}

func acquireForkLock() {
	ForkLock.Lock()
}

func releaseForkLock() {
	ForkLock.Unlock()

	}()

	flags, err := unix.Fcntl(gotFDs[0], syscall.F_GETFD, 0)
	if err != nil {
		t.Fatalf("Can't get flags of fd:%#v, with err:%v", gotFDs[0], err)
	}
	if flags&syscall.FD_CLOEXEC == 0 {
		t.Fatalf("got flags %#x, want %#x (FD_CLOEXEC) set", flags, syscall.FD_CLOEXEC)
	}

	t.Helper()
	flags, errno := runtime.Fcntl(fd, syscall.F_GETFD, 0)
	if flags == -1 {
		t.Errorf("fcntl(%s, F_GETFD) failed: %v", name, syscall.Errno(errno))
	} else if flags&syscall.FD_CLOEXEC == 0 {
		t.Errorf("FD_CLOEXEC not set in %s flags %#x", name, flags)
	}

		} else {
			_, _, err1 = RawSyscall(SYS_DUP2, uintptr(pipe), uintptr(nextfd), 0)
			if err1 != 0 {
				goto childerror
			}
			_, _, err1 = RawSyscall(SYS_FCNTL, uintptr(nextfd), F_SETFD, FD_CLOEXEC)
		}
		if err1 != 0 {
			goto childerror
		}
		pipe = nextfd
		nextfd++
	}
	for i = 0; i < len(fd); i++ {
		if fd[i] >= 0 && fd[i] < i {
			if nextfd == pipe { // don't stomp on pipe

			_, _, err1 = rawSyscall(dupTrampoline, uintptr(pipe), uintptr(nextfd), 0)
			if err1 != 0 {
				goto childerror
			}
			_, _, err1 = rawSyscall(abi.FuncPCABI0(libc_fcntl_trampoline), uintptr(nextfd), F_SETFD, FD_CLOEXEC)
		}
		if err1 != 0 {
			goto childerror
		}
		pipe = nextfd
		nextfd++
	}
	for i = 0; i < len(fd); i++ {
		if fd[i] >= 0 && fd[i] < i {
			if nextfd == pipe { // don't stomp on pipe

		default:
			_, err1 = dup2child(uintptr(pipe), uintptr(nextfd))
			if err1 != 0 {
				goto childerror
			}
			_, err1 = fcntl1(uintptr(nextfd), F_SETFD, FD_CLOEXEC)
		}
		if err1 != 0 {
			goto childerror
		}
		pipe = nextfd
		nextfd++
	}
	for i = 0; i < len(fd); i++ {
		if fd[i] >= 0 && fd[i] < i {
			if nextfd == pipe { // don't stomp on pipe

	b := make([]byte, n)
	n = 0
	for i, s := range ss {
		bb[i] = &b[n]
		copy(b[n:], s)
		n += len(s) + 1
	}
	return bb, nil
}

func CloseOnExec(fd int) { fcntl(fd, F_SETFD, FD_CLOEXEC) }

func SetNonblock(fd int, nonblocking bool) (err error) {
	flag, err := fcntl(fd, F_GETFL, 0)
	if err != nil {
		return err
	}
	if (flag&O_NONBLOCK != 0) == nonblocking {
		return nil
	}