ZipInfo中的external_attr和internal_attr指的是什么？

Question

我看不到external_attr和internal_attr实际指的解释（如果有区别，则在python2和python3中都使用）。

https://docs.python.org/3/library/zipfile.html

有人可以提供任何细节吗？

Answer 1

这很有趣，源代码也没有使它变得显而易见，而是由著名的Python开发人员David Beazley着书Python Essential Reference。

internal_attr描述档案内容的内部结构。如果低位为1，则数据为ASCII文本。否则，将假定为二进制数据。
external_attr依赖于操作系统的外部文件属性。

Answer 2

PKZIP Application Note（在 Python docs for zipfile 中引用）声明如下：

4.4.15 external file attributes: (4 bytes)

    The mapping of the external attributes is
    host-system dependent (see 'version made by').  For
    MS-DOS, the low order byte is the MS-DOS directory
    attribute byte.  If input came from standard input, this
    field is set to zero.

4.4.14 internal file attributes: (2 bytes)

    Bits 1 and 2 are reserved for use by PKWARE.

    4.4.14.1 The lowest bit of this field indicates, if set, 
    that the file is apparently an ASCII or text file.  If not
    set, that the file apparently contains binary data.
    The remaining bits are unused in version 1.0.

    4.4.14.2 The 0x0002 bit of this field indicates, if set, that 
    a 4 byte variable record length control field precedes each 
    logical record indicating the length of the record. The 
    record length control field is stored in little-endian byte
    order.  This flag is independent of text control characters, 
    and if used in conjunction with text data, includes any 
    control characters in the total length of the record. This 
    value is provided for mainframe data transfer support.