ErrNotExist   = fs.ErrNotExist   // "file does not exist"
	ErrClosed     = fs.ErrClosed     // "file already closed"

	ErrNoDeadline       = errNoDeadline()       // "file type does not support deadline"
	ErrDeadlineExceeded = errDeadlineExceeded() // "i/o timeout"
)

func errNoDeadline() error { return poll.ErrNoDeadline }

// errDeadlineExceeded returns the value for os.ErrDeadlineExceeded.

// ErrFileClosing is returned when a file descriptor is used after it
// has been closed.
var ErrFileClosing = errors.New("use of closed file")

// ErrNoDeadline is returned when a request is made to set a deadline
// on a file type that does not use the poller.
var ErrNoDeadline = errors.New("file type does not support deadline")

// Return the appropriate closing error based on isFile.
func errClosing(isFile bool) error {
	if isFile {

		if d == 0 {
			d = -1 // don't confuse deadline right now with no deadline
		}
	}
	if err := fd.incref(); err != nil {
		return err
	}
	defer fd.decref()
	if fd.pd.runtimeCtx == 0 {
		return ErrNoDeadline
	}
	runtime_pollSetDeadline(fd.pd.runtimeCtx, d, mode)
	return nil
}

// IsPollDescriptor reports whether fd is the descriptor being used by the poller.
// This is only used for testing.
//