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Title: Incorrect extraction
Type: behavior Stage: resolved
Components: Library (Lib) Versions: Python 3.2, Python 3.3, Python 2.7
Status: closed Resolution: fixed
Dependencies: Superseder:
Assigned To: lars.gustaebel Nosy List: doughellmann, eric.araujo, lars.gustaebel, loewis, python-dev, seblu, vstinner
Priority: normal Keywords: patch

Created on 2011-08-25 14:17 by seblu, last changed 2022-04-11 14:57 by admin. This issue is now closed.

File name Uploaded Description Edit
tarfile-bug.patch seblu, 2011-08-25 14:17 review
Messages (13)
msg142969 - (view) Author: Sebastien Luttringer (seblu) Date: 2011-08-25 14:17
This patch fix extraction of tarfile which override tarfile uid/gid extract function override uid/gid of a file if uid/gid is not
existant on the system.

When user is not root (uid 0), common behaviour of extracting is correct.
When user is root, python implementation try to preserve (like tar -p) ownership
from tarball, but if uid/gid doesn't exist it remplace by process uid/gid.
This leads to fake the expected behaviour of preservation!

By example, extracting tarball with a root filesystem will create incorrect
ownership for file where owner/group is not on the current filesystem.
msg142970 - (view) Author: Martin v. Löwis (loewis) * (Python committer) Date: 2011-08-25 14:32
Lars, any comment?
msg143100 - (view) Author: Lars Gustäbel (lars.gustaebel) * (Python committer) Date: 2011-08-28 16:06
The patch is fine. Thank you very much for it, Sebastien. I think we have to go without a unit test.
msg143121 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2011-08-28 20:00
Should this bug be fixed in 3.3, or 2.7+3.2+3.3?
msg143130 - (view) Author: Lars Gustäbel (lars.gustaebel) * (Python committer) Date: 2011-08-29 07:14
Yes, it should be fixed in all affected branches.
msg143131 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2011-08-29 08:19
The patch looks ok. Can you push it Lars?
msg143172 - (view) Author: Lars Gustäbel (lars.gustaebel) * (Python committer) Date: 2011-08-29 18:35
Yes, I can do that as soon as I've managed to wrap my head around using Mercurial and the new way of developing Python. I have been away from Python programming for quite some time and haven't adapted my workflow yet.
msg143175 - (view) Author: STINNER Victor (vstinner) * (Python committer) Date: 2011-08-29 19:37
You can get a lot of information on this guide:

You can also ask on IRC (#python-dev on Freenode), or by email on the python-dev mailing list.

It was really hard for me to switch from Subversion to Mercurial. Not because of the merge and the push things, but because of the 4 different Python branches! So don't hesitate to ask me questions about how I use Mercurial ;-)
msg143524 - (view) Author: Roundup Robot (python-dev) (Python triager) Date: 2011-09-05 15:14
New changeset 2bc122347351 by Lars Gustäbel in branch '3.2':
Issue #12841: Fix tarfile extraction of non-existent uids/gids.

New changeset da59abc0ce3b by Lars Gustäbel in branch 'default':
Merge with 3.2: Issue #12841: Fix tarfile extraction of non-existent uids/gids.

New changeset b64ef2951093 by Lars Gustäbel in branch '2.7':
Issue #12841: Fix tarfile extraction of non-existent uids/gids.
msg143528 - (view) Author: Lars Gustäbel (lars.gustaebel) * (Python committer) Date: 2011-09-05 15:19
Close as fixed. Thanks all!
msg143769 - (view) Author: Éric Araujo (eric.araujo) * (Python committer) Date: 2011-09-09 16:57
> I think we have to go without a unit test.
May I ask why?  I don’t know tarfile well, but I know that a lot can be done with unittest.
msg143804 - (view) Author: Lars Gustäbel (lars.gustaebel) * (Python committer) Date: 2011-09-09 21:40
It's the low-level operating system aspects of tarfile that are very difficult to test, e.g. filesystem and operating system dependent features such as symbolic links, hard links, file permissions, ownership. It is not even possible to reliably determine the filesystem the testsuite currently runs on. Also, superuser privileges are needed for some operations to work, e.g. chown(). A testsuite is normally not run as root, so a test that depends on this will never get enough coverage.
msg143909 - (view) Author: Éric Araujo (eric.araujo) * (Python committer) Date: 2011-09-12 15:47
I understand.  Unit tests can work with file permissions, ownership and links, but they can’t create different filesystems or ask for superuser rights.  test_shutil contains a few tests that purport to test cross-filesystems usage but may or may not actually do it (#9999).
Date User Action Args
2022-04-11 14:57:21adminsetgithub: 57050
2011-09-12 15:47:41eric.araujosetmessages: + msg143909
2011-09-09 21:40:48lars.gustaebelsetmessages: + msg143804
2011-09-09 16:57:33eric.araujosetnosy: + eric.araujo
messages: + msg143769
2011-09-05 15:19:59lars.gustaebelsetstatus: open -> closed
resolution: fixed
messages: + msg143528

stage: resolved
2011-09-05 15:14:43python-devsetnosy: + python-dev
messages: + msg143524
2011-09-02 10:15:00doughellmannsetnosy: + doughellmann
2011-09-02 08:58:20lars.gustaebelsetversions: + Python 2.7, Python 3.3
2011-08-29 19:37:06vstinnersetmessages: + msg143175
2011-08-29 18:35:28lars.gustaebelsetmessages: + msg143172
2011-08-29 08:19:29vstinnersetmessages: + msg143131
2011-08-29 07:14:50lars.gustaebelsetmessages: + msg143130
2011-08-28 20:00:58vstinnersetmessages: + msg143121
2011-08-28 16:06:38lars.gustaebelsetmessages: + msg143100
2011-08-25 15:24:02vstinnersetnosy: + vstinner
2011-08-25 14:32:28loewissetassignee: lars.gustaebel

messages: + msg142970
nosy: + loewis, lars.gustaebel
2011-08-25 14:17:13seblucreate