numpy_pickle_utils.py 文件源码

def _read_bytes(fp, size, error_template="ran out of data"):
    """Read from file-like object until size bytes are read.

    Raises ValueError if not EOF is encountered before size bytes are read.
    Non-blocking objects only supported if they derive from io objects.

    Required as e.g. ZipExtFile in python 2.6 can return less data than
    requested.

    This function was taken from numpy/lib/format.py in version 1.10.2.

    Parameters
    ----------
    fp: file-like object
    size: int
    error_template: str

    Returns
    -------
    a bytes object
        The data read in bytes.

    """
    data = bytes()
    while True:
        # io files (default in python3) return None or raise on
        # would-block, python2 file will truncate, probably nothing can be
        # done about that.  note that regular files can't be non-blocking
        try:
            r = fp.read(size - len(data))
            data += r
            if len(r) == 0 or len(data) == size:
                break
        except io.BlockingIOError:
            pass
    if len(data) != size:
        msg = "EOF: reading %s, expected %d bytes got %d"
        raise ValueError(msg % (error_template, size, len(data)))
    else:
        return data