FileInputSource::unreadCh(char ch)
{
    QUtil::os_wrapper(this->filename + ": unread character",
		      ungetc(static_cast<unsigned char>(ch), this->file));
}
FileInputSource::unreadCh(char ch)
{
    QUtil::os_wrapper(this->filename + ": unread character",
		      ungetc(static_cast<unsigned char>(ch), this->file));
}