gzip: cannot create file if mtime > `2106-02-07T06:28:15`

Bug report

Bug description:

We had a VM where ntp went very wonky and ended up thinking it was the year 2141!
Trying to write a gzip file with the system clock greater than 2106-02-07T06:28:15 results in a struct error because we tried to cram a 64-bit int into a 32 bit field (which won't work).

I wouldn't expect the gzip module to explode in this case, I'd expect it to set the MTIME to 0.
RFC 1952 (if that's at all relevant these days) states

MTIME = 0 means no time stamp is available

MWE

Only tested this on macOS on 3.13.2, but from a cursory glance, the mtime handling hasn't changed in over a decade.

>>> import gzip
>>> gzip.GzipFile("/dev/null", "w", mtime=2**32+1)
Traceback (most recent call last):
  File "<python-input-3>", line 1, in <module>
    gzip.GzipFile("/dev/null", "w", mtime=2**32+1)
    ~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/gzip.py", line 237, in __init__
    self._write_gzip_header(compresslevel)
    ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/gzip.py", line 281, in _write_gzip_header
    write32u(self.fileobj, int(mtime))
    ~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/gzip.py", line 77, in write32u
    output.write(struct.pack("<L", value))
                 ~~~~~~~~~~~^^^^^^^^^^^^^
struct.error: 'L' format requires 0 <= number <= 4294967295

Proposed Patch

I'd naïvely fix it with this patch

diff --git a/Lib/gzip.py b/Lib/gzip.py
index c00f51858de..29345de4659 100644
--- a/Lib/gzip.py
+++ b/Lib/gzip.py
@@ -297,6 +297,8 @@ def _write_gzip_header(self, compresslevel):
         mtime = self._write_mtime
         if mtime is None:
             mtime = time.time()
+        if mtime > 4294967295:
+            mtime = 0
         write32u(self.fileobj, int(mtime))
         if compresslevel == _COMPRESS_LEVEL_BEST:
             xfl = b'\002'

CPython versions tested on:

3.13

Operating systems tested on:

macOS

Linked PRs

• gh-134278
• gh-150221
• gh-151828

Bắt đầu trong Lib/gzip.py tại _write_gzip_header và tái hiện ví dụ GzipFile được cung cấp với mtime vượt quá phạm vi 32 bit. Kiểm tra các PR được liên kết trước khi bắt đầu làm việc, vì chúng cho thấy vấn đề này có thể đã được xử lý. Được coi là hoàn tất khi tệp gzip được tạo với MTIME được đặt thành 0 thay vì phát sinh struct.error.