py2.py 文件源码

def truncate(self, size=-1):
            self.flush()
            if size == -1:
                size = self.tell()
            try:
                rv = os.ftruncate(self.fileno(), size)
            except OSError as e:
                raise IOError(*e.args)
            else:
                self.seek(size)  # move position&clear buffer
                return rv