// Errno values.
const (
	errnoERROR_IO_PENDING = 997
)

var (
	errERROR_IO_PENDING error = syscall.Errno(errnoERROR_IO_PENDING)
	errERROR_EINVAL     error = syscall.EINVAL
)

// errnoErr returns common boxed Errno values, to prevent
// allocations at runtime.
func errnoErr(e syscall.Errno) error {
	switch e {
	case 0:
		return errERROR_EINVAL
	case errnoERROR_IO_PENDING:

	// so we don't permit it to remain consistent with the
	// "at" implementation of RemoveAll.
	if endsWithDot(path) {
		return &PathError{Op: "RemoveAll", Path: path, Err: syscall.EINVAL}
	}

	// Simple case: if Remove works, we're done.
	err := Remove(path)
	if err == nil || IsNotExist(err) {
		return nil
	}

	// Otherwise, is this a directory we need to recurse into?

// pointers to NUL-terminated byte arrays. If any string contains
// a NUL byte, it returns (nil, [EINVAL]).
func SlicePtrFromStrings(ss []string) ([]*byte, error) {
	n := 0
	for _, s := range ss {
		if bytealg.IndexByteString(s, 0) != -1 {
			return nil, EINVAL
		}
		n += len(s) + 1 // +1 for NUL
	}
	bb := make([]*byte, len(ss)+1)
	b := make([]byte, n)
	n = 0
	for i, s := range ss {

func isSysErrNoSpace(err error) bool {
	return errors.Is(err, syscall.ENOSPC)
}

// Invalid argument, unsupported flags such as O_DIRECT
func isSysErrInvalidArg(err error) bool {
	return errors.Is(err, syscall.EINVAL)
}

// Input/output error
func isSysErrIO(err error) bool {
	return errors.Is(err, syscall.EIO)
}

// Check if the given error corresponds to EISDIR (is a directory).
func isSysErrIsDir(err error) bool {

	//
	// Checking for statusDone here would not be a complete fix, as the PID
	// could still be waited on and reused prior to blockUntilWaitable.
	switch p.pidStatus() {
	case statusReleased:
		return nil, syscall.EINVAL
	}

	// If we can block until Wait4 will succeed immediately, do so.
	ready, err := p.blockUntilWaitable()
	if err != nil {
		return nil, err
	}
	if ready {

	if err != nil {
		t.Errorf("Faccessat: unexpected error: %v", err)
	}

	err = syscall.Faccessat(_AT_FDCWD, "file1", _R_OK, 2)
	if err != syscall.EINVAL {
		t.Errorf("Faccessat: unexpected error: %v, want EINVAL", err)
	}

	err = syscall.Faccessat(_AT_FDCWD, "file1", _R_OK, _AT_EACCESS)
	if err != nil {
		t.Errorf("Faccessat: unexpected error: %v", err)
	}

func Pipe(p []int) (err error) {
	if len(p) != 2 {
		return EINVAL
	}
	r, w, err := pipe()
	if err == nil {
		p[0], p[1] = r, w
	}
	return err
}

//sysnb	pipe2(p *[2]_C_int, flags int) (r int, w int, err error)

func Pipe2(p []int, flags int) (err error) {
	if len(p) != 2 {
		return EINVAL
	}
	var pp [2]_C_int

	if r1 == socket_error {
		if e1 != 0 {
			err = errnoErr(e1)
		} else {
			err = syscall.EINVAL
		}
	}
	return err
}

func WSARecvMsg(fd syscall.Handle, msg *WSAMsg, bytesReceived *uint32, overlapped *syscall.Overlapped, croutine *byte) error {
	err := loadWSASendRecvMsg()
	if err != nil {

		// pidfdFind. Return ECHILD for consistency with what the wait
		// syscall would return.
		return nil, NewSyscallError("wait", syscall.ECHILD)
	case statusReleased:
		return nil, syscall.EINVAL
	}
	defer p.handleTransientRelease()

	var (
		info   unix.SiginfoChild
		rusage syscall.Rusage
		e      syscall.Errno
	)
	for {

func initMPTCPavailable() {
	s, err := sysSocket(syscall.AF_INET, syscall.SOCK_STREAM, _IPPROTO_MPTCP)
	switch {
	case errors.Is(err, syscall.EPROTONOSUPPORT): // Not supported: >= v5.6
	case errors.Is(err, syscall.EINVAL): // Not supported: < v5.6
	case err == nil: // Supported and no error
		poll.CloseFunc(s)
		fallthrough
	default:
		// another error: MPTCP was not available but it might be later
		mptcpAvailable = true
	}