connections.py 文件源码

def _copy_stream(self, fd, url, offset):
        """Copies remote file to local.

        :param fd: the file`s descriptor
        :param url: the remote file`s url
        :param offset: the number of bytes from the beginning,
                       that will be skipped
        :return: the count of actually copied bytes
        """

        source = self.open_stream(url, offset)
        os.ftruncate(fd, offset)
        os.lseek(fd, offset, os.SEEK_SET)
        chunk_size = 16 * 1024
        size = 0
        while 1:
            chunk = source.read(chunk_size)
            if not chunk:
                break
            os.write(fd, chunk)
            size += len(chunk)
        return size