gh-103861: Fix Zip64 extensions not being properly applied in some cases

[pR0Ps]

This commit fixes an issue where adding a small file to a ZipFile object while forcing zip64 extensions causes an extra Zip64 record to be added to the zip, but doesn't update the min_version or file sizes.

To create a file that reproduces the issue (copied from #103861):

import zipfile with zipfile.ZipFile("out.zip", mode="w", allowZip64=True) as zf: with zf.open("text.txt", mode="w", force_zip64=True) as zi: zi.write(b"some data")

Diff of information extracted by zipdetails from running the above script before and after this commit.

 0000 LOCAL HEADER #1 04034B50 -0004 Extract Zip Spec 14 '2.0' +0004 Extract Zip Spec 2D '4.5' 0005 Extract OS 00 'MS-DOS' 0006 General Purpose Flag 0000 0008 Compression Method 0000 'Stored' 000A Last Mod Time 00210000 'Mon Dec 31 19:00:00 1979' 000E CRC D9C2E91E -0012 Compressed Length 00000009 -0016 Uncompressed Length 00000009 +0012 Compressed Length FFFFFFFF +0016 Uncompressed Length FFFFFFFF 001A Filename Length 0008 001C Extra Length 0014 001E Filename 'text.txt' 0026 Extra ID #0001 0001 'ZIP64' 0028 Length 0010 002A Uncompressed Size 0000000000000009 0032 Compressed Size 0000000000000009 003A PAYLOAD some data 0043 CENTRAL HEADER #1 02014B50 -0047 Created Zip Spec 14 '2.0' +0047 Created Zip Spec 2D '4.5' 0048 Created OS 03 'Unix' -0049 Extract Zip Spec 14 '2.0' +0049 Extract Zip Spec 2D '4.5' 004A Extract OS 00 'MS-DOS' 004B General Purpose Flag 0000 004D Compression Method 0000 'Stored' 004F Last Mod Time 00210000 'Mon Dec 31 19:00:00 1979' 0053 CRC D9C2E91E 0057 Compressed Length 00000009 005B Uncompressed Length 00000009 005F Filename Length 0008 0061 Extra Length 0000 0063 Comment Length 0000 0065 Disk Start 0000 0067 Int File Attributes 0000 [Bit 0] 0 'Binary Data' 0069 Ext File Attributes 01800000 006D Local Header Offset 00000000 0071 Filename 'text.txt' 0079 END CENTRAL HEADER 06054B50 007D Number of this disk 0000 007F Central Dir Disk no 0000 0081 Entries in this disk 0001 0083 Total Entries 0001 0085 Size of Central Dir 00000036 0089 Offset to Central Dir 00000043 008D Comment Length 0000

A test has also been added that checks that these properties are correctly set.

• Issue: Writing a small file into a ZipFile while forcing zip64 extensions results in an incorrect zip file #103861

Potential reviewer based on the git blame of the changed lines: @serhiy-storchaka (182d7cd)
Potential reviewers based on the experts index: @Yhg1s, @gpshead

[gpshead]

I think this is the issue you were talking about at lunch today? (yay pycon sprints!)

[pR0Ps]

Yep, that's this one!

[pR0Ps]

@gpshead Addressed review comments

[gpshead]

github actions CI infrastructure seems broken at the moment. But I think this the PR is ready.

I undid one part of your change so it'd remain a pure bugfix: ZipInfo.FileHeader() is technically a public API - even if it seems like nothing should use it we must assume someone does. So getting rid of the old zip64=None default behavior would be an API change, so I restored that. But it should be a no-op as FileHeader is always called with an explicit zip64 bool supplied within the zipfile module itself.

I'll take another look later and rerun CI after it's healthy again.

[miss-islington]

Thanks @pR0Ps for the PR, and @gpshead for merging it 🌮🎉.. I'm working now to backport this PR to: 3.11.
🐍🍒⛏🤖

[miss-islington]

Sorry, @pR0Ps and @gpshead, I could not cleanly backport this to 3.11 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 798bcaa1eb01de7db9ff1881a3088603ad09b096 3.11

[bedevere-bot]

GH-104534 is a backport of this pull request to the 3.11 branch.