https://github.com/python/cpython/commit/9a388b9a64927c372d85f0eaec3de9b7320a6fb5 commit: 9a388b9a64927c372d85f0eaec3de9b7320a6fb5 branch: main author: Joachim Wuttke <[email protected]> committer: encukou <[email protected]> date: 2024-03-28T13:43:07Z summary:
bpo-43848: explain optional argument mtime in gzip.py. (GH-25410) Co-authored-by: Jelle Zijlstra <[email protected]> files: A Misc/NEWS.d/next/Library/2024-03-28-13-54-20.gh-issue-88014.zJz31I.rst M Doc/library/gzip.rst M Lib/gzip.py diff --git a/Doc/library/gzip.rst b/Doc/library/gzip.rst index 79be215a766045..044be8c1c1bf41 100644 --- a/Doc/library/gzip.rst +++ b/Doc/library/gzip.rst @@ -100,10 +100,12 @@ The module defines the following items: compression, and ``9`` is slowest and produces the most compression. ``0`` is no compression. The default is ``9``. - The *mtime* argument is an optional numeric timestamp to be written to - the last modification time field in the stream when compressing. It - should only be provided in compression mode. If omitted or ``None``, the - current time is used. See the :attr:`mtime` attribute for more details. + The optional *mtime* argument is the timestamp requested by gzip. The time + is in Unix format, i.e., seconds since 00:00:00 UTC, January 1, 1970. + If *mtime* is omitted or None, the current time is used. Use *mtime* = 0 + to generate a compressed stream that does not depend on creation time. + + See below for the :attr:`mtime` attribute that is set when decompressing. Calling a :class:`GzipFile` object's :meth:`!close` method does not close *fileobj*, since you might wish to append more material after the compressed @@ -133,15 +135,10 @@ The module defines the following items: .. attribute:: mtime - When decompressing, the value of the last modification time field in - the most recently read header may be read from this attribute, as an - integer. The initial value before reading any headers is ``None``. - - All :program:`gzip` compressed streams are required to contain this - timestamp field. Some programs, such as :program:`gunzip`\ , make use - of the timestamp. The format is the same as the return value of - :func:`time.time` and the :attr:`~os.stat_result.st_mtime` attribute of - the object returned by :func:`os.stat`. + When decompressing, this attribute is set to the last timestamp in the most + recently read header. It is an integer, holding the number of seconds + since the Unix epoch (00:00:00 UTC, January 1, 1970). + The initial value before reading any headers is ``None``. .. attribute:: name diff --git a/Lib/gzip.py b/Lib/gzip.py index fda93e0261e028..1d6faaa82c6a68 100644 --- a/Lib/gzip.py +++ b/Lib/gzip.py @@ -178,9 +178,10 @@ def __init__(self, filename=None, mode=None, and 9 is slowest and produces the most compression. 0 is no compression at all. The default is 9. - The mtime argument is an optional numeric timestamp to be written - to the last modification time field in the stream when compressing. - If omitted or None, the current time is used. + The optional mtime argument is the timestamp requested by gzip. The time + is in Unix format, i.e., seconds since 00:00:00 UTC, January 1, 1970. + If mtime is omitted or None, the current time is used. Use mtime = 0 + to generate a compressed stream that does not depend on creation time. """ diff --git a/Misc/NEWS.d/next/Library/2024-03-28-13-54-20.gh-issue-88014.zJz31I.rst b/Misc/NEWS.d/next/Library/2024-03-28-13-54-20.gh-issue-88014.zJz31I.rst new file mode 100644 index 00000000000000..f8bb784e39fbb6 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2024-03-28-13-54-20.gh-issue-88014.zJz31I.rst @@ -0,0 +1,3 @@ +In documentation of :class:`gzip.GzipFile` in module gzip, explain data type +of optional constructor argument *mtime*, and recommend ``mtime = 0`` for +generating deterministic streams. _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3/lists/python-checkins.python.org/ Member address: [email protected]
