Zipfile.extractall does not preserve file permissions

[uruz]

BPO	15795
Nosy	@ronaldoussoren, @abalkin, @gustaebel, @pitrou, @kmtracey, @merwok, @bitdancer, @PCManticore, @serhiy-storchaka, @mikofski, @nanjekyejoannah, @woodruffw, @Makishima, @selimb, @dignissimus
PRs	bpo-15795: Preserve permissions on UNIX (based/like) systems #17790 gh-59999: Add option to preserve permissions in ZipFile.extract #32289
Files	issue15795.patch issue15795_updated.patch issue15795_cleaned.patch issue15795_test_and_doc_fixes.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/serhiy-storchaka'
closed_at = None
created_at = <Date 2012-08-27.22:36:03.648>
labels = ['type-feature', 'library', '3.11']
title = 'Zipfile.extractall does not preserve file permissions'
updated_at = <Date 2022-04-04.14:55:21.787>
user = 'https://bugs.python.org/uruz'

bugs.python.org fields:

activity = <Date 2022-04-04.14:55:21.787>
actor = 'eric.araujo'
assignee = 'serhiy.storchaka'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2012-08-27.22:36:03.648>
creator = 'uruz'
dependencies = []
files = ['27086', '34852', '34873', '34893']
hgrepos = []
issue_num = 15795
keywords = ['patch']
message_count = 24.0
messages = ['169233', '169242', '169629', '174356', '174359', '191425', '191459', '216228', '216267', '216298', '216304', '216376', '225526', '233445', '237139', '261145', '283918', '311328', '378712', '394819', '404877', '416661', '416672', '416674']
nosy_count = 24.0
nosy_names = ['ronaldoussoren', 'belopolsky', 'lars.gustaebel', 'pitrou', 'techtonik', 'swarren', 'kmtracey', 'eric.araujo', 'cbrannon', 'r.david.murray', 'Claudiu.Popa', 'serhiy.storchaka', 'uruz', 'Aaron.Train', 'desaintmartin', 'bwanamarko', 'Orborde', 'Glenn.Jones', '\xc3\x89tienne Dupuis', 'nanjekyejoannah', 'yossarian', 'kulakov-n', 'selimb', 'sam_ezeh']
pr_nums = ['17790', '32289']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue15795'
versions = ['Python 3.11']

[uruz]

Zipfile._extract_member does not preserve file permissions while extracting it. As may be seen at link[1], raw open() is used and no os.chmod() applied after that, therefore any permission data stored in zipfile is dropped and file is created with default permission depending on current user's umask.

[1] http://hg.python.org/cpython/file/52159aa5d401/Lib/zipfile.py#l1251

[bitdancer]

Does this have any relationship to bpo-3394? From the discussion on that issue it sounds like zipfile is doing things with external_attributes if it is set. But I don't know much about zipfile internals.

[uruz]

I'm attaching a patch, which solves the issue. Patch intoduces new argument "preserve_permissions" for extract and extractall methods. That argument may accept one of the three values: do not preserve permissions, preserve a safe subset of them or preserve all permissions. Three constants introduced for these options. Patch also contains test and docs. Tests pass for me on OS X 10.5, but I'm not sure if they'll pass on other operating systems.

[AaronTrain]

Thanks for the patch. Is this going to be resolved soon?

[bitdancer]

OK, so this is an enhancement to specifically allow preservation of "unsafe" permissions?

Adding the nosy list from bpo-3394.

[techtonik]

There should be an easy way to restore file attributes.

[ronaldoussoren]

On first glance the patch looks good. I haven't tested it with the current trunk though.

[GlennJones]

Here is an updated patch that applies cleanly to head. Tests pass against head of repo.

[bitdancer]

Thanks.

The patch contains a number of lines that are not wrapped to <80, which is one of our requirements. It would be great to get that fixed. (In the documentation, you can use \ to wrap the prototype line.)

There is non-ascii in one place in the documentation...probably an em-dash, which is written in sphinx as '---'.

Also, please remove the news entry from the patch, it will just make it harder to apply (and is in the wrong place anyway...we add entries at the top of the appropriate section, not the bottom).

[GlennJones]

Patch cleaned up based on previous comments.

[PCManticore]

Hello. I added a couple of comments to your latest patch.