Enable for ZipFile to specify to create archives of arbitrary windows FAT or Unix filesystem

[Wiktorro]

Feature or enhancement

Proposal:

Hi, as dev working with app designed for both Windows, Mac and Linux systems, I had recently automating with ZipFile task of repacking some internal ZIP archives. To automate the task even more, I created formulas for each of systems to be available on single script, on single call (and so on one machine) to create packages easier.

Unfortunately generated tasks were faulty,
I noticed, that same script performed on Linux or Windows created archives of different types - FAT or UNX, therefore output files were seen as invalid on opposite system.

To make the picture, my flow was:
start on particular OS (either Windows or Linux) ==> download archive from web (fixed format, UNX or FAT) ==> unpacking archive ==> creating new archive from files from previous ==> resulting archive has format from OS, overriding input archive (while I need the exact opposite)

Could I ask You to add possibility from code to enforce archiving files by chosen system , for instance like a compression method (like I chose LZMA), like I suggest below ? Or maybe if it is dependent on the format of the not yet archived input , could a similar flag enforce unpacking file in chosen filesystem , not being dependent on the used machine and OS?
I also provide some output from zipinfo console utility.

I attach some links that hopefully might present the issue,
https://en.wikipedia.org/wiki/FAT_filesystem_and_Linux
https://forensics.wiki/zip/#external-file-attributes

Best regards and have a good day, also feel free to contact me for more info, Wiktor

class zipfile.ZipFile(file, filesystem='FAT/UNX', ...
ZipFile.write(filename, filesystem='FAT/UNX', ...

class zipfile.ZipFile(file, filesystem='FAT/UNX', ... 
ZipFile.write(filename, filesystem='FAT/UNX', ...

packed on Windows

zipinfo ~/Downloads/win7.1.5_sandbox.zip
Archive: win7.1.5_sandbox.zip
Zip file size: 47379022 bytes, number of entries: 92
drwx--- 6.3 fat 0 bx stor 25-Mar-12 11:41 Debug/
....
-rwx--- 6.3 fat 20554528 bx lzma 25-Mar-11 16:17 someWinApp.exe
....
-rwx--- 6.3 fat 422168 bx lzma 25-Mar-11 16:18 someWinApp2.exe
92 files, 205285623 bytes uncompressed, 47362726 bytes compressed: 76.9%

packed on Mac

zipinfo ~/Downloads/mac7.1.4_sandbox.zip
Archive: mac7.1.4_sandbox.zip
Zip file size: 93026056 bytes, number of entries: 160
drwxr-xr-x 6.3 unx 0 bx stor 25-Feb-14 01:00 .package/
drwxr-xr-x 6.3 unx 0 bx stor 25-Feb-14 00:59 RuntimeRoots/
-rwxr-xr-x 6.3 unx 25375808 bx lzma 25-Feb-14 01:00 someApp
...
-rwxr-xr-x 6.3 unx 11167424 bx lzma 25-Feb-14 01:00 someApp2
....
-rwxr-xr-x 6.3 unx 2053072 bx someApp3
-rw-r--r-- 6.3 unx 4315 bx lzma 25-Feb-10 09:30 headerfile.h
160 files, 409689641 bytes uncompressed, 92994544 bytes compressed: 77.3%

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

[thatch]

Are you basically asking for this to be overridable?

cpython/Lib/zipfile/__init__.py

Lines 428 to 432 in ec39fd2

	if sys.platform == 'win32':
	self.create_system = 0 # System which created ZIP archive
	else:
	# Assume everything else is unix-y
	self.create_system = 3 # System which created ZIP archive

[Wiktorro]

Are you basically asking for this to be overridable?

cpython/Lib/zipfile/init.py

Lines 428 to 432 in ec39fd2
if sys.platform == 'win32':
self.create_system = 0 # System which created ZIP archive
else:
# Assume everything else is unix-y
self.create_system = 3 # System which created ZIP archive

Hi, thanks a lot for this snippet,
Yes indeed I think that would be the right approach, exactly allowing to override such check when demanded.
I was thinking recently if just "binary reading certain files from source archive" would be the way to preserve system format, but good to know ZipInfo handles members this way on.