shared/eagain/file.go
func (er Reader) Read(p []byte) (int, error) {
again:
	n, err := er.Reader.Read(p)
	if err == nil {
		return n, nil
	}

	// keep retrying on EAGAIN
	errno, ok := shared.GetErrno(err)
	if ok && (errno == syscall.EAGAIN || errno == syscall.EINTR) {
		goto again
	}

	return n, err
}
func (er Reader) Read(p []byte) (int, error) {
again:
	n, err := er.Reader.Read(p)
	if err == nil {
		return n, nil
	}

	// keep retrying on EAGAIN
	errno, ok := shared.GetErrno(err)
	if ok && (errno == syscall.EAGAIN || errno == syscall.EINTR) {
		goto again
	}

	return n, err
}
// Read behaves like io.Reader.Read but will retry on EAGAIN