tarfile.py 文件源码

def read(self, size=None):
        """Read at most size bytes from the file. If size is not
           present or None, read all data until EOF is reached.
        """
        if self.closed:
            raise ValueError("I/O operation on closed file")

        buf = ""
        if self.buffer:
            if size is None:
                buf = self.buffer
                self.buffer = ""
            else:
                buf = self.buffer[:size]
                self.buffer = self.buffer[size:]

        if size is None:
            buf += self.fileobj.read()
        else:
            buf += self.fileobj.read(size - len(buf))

        self.position += len(buf)
        return buf