TarFile.getmember cannot work on tar sourced directory over 100 characters

[cfernald]

BPO	47231
Nosy	@bitdancer, @ethanfurman, @serhiy-storchaka, @akulakov, @cfernald
Files	tarfile_repro.py: Example of tarfile bug using arm gcc compiler tarfile

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

Show more details

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2022-04-05.18:15:20.584>
labels = ['type-bug', 'library', '3.9', '3.10', '3.11']
title = 'TarFile.getmember cannot work on tar sourced directory over 100 characters'
updated_at = <Date 2022-04-05.22:06:10.413>
user = 'https://github.com/cfernald'

bugs.python.org fields:

activity = <Date 2022-04-05.22:06:10.413>
actor = 'vstinner'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2022-04-05.18:15:20.584>
creator = 'cfernald'
dependencies = []
files = ['50721']
hgrepos = []
issue_num = 47231
keywords = []
message_count = 2.0
messages = ['416793', '416796']
nosy_count = 5.0
nosy_names = ['r.david.murray', 'ethan.furman', 'serhiy.storchaka', 'andrei.avk', 'cfernald']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue47231'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']

[cfernald]

A fix was made to unify handling of the trailing slash in TarFile.getmember related to https://bugs.python.org/issue21987. This change fixed the <100 character case, but made it so directories over 100 character which come from a tar file can no longer be accessed through getmember, even if returned from getnames. This appears to be because internal to tarfile, member names still include the trailing slash on directories over 100 characters but getmember will always remove the trailing slash from the provided name so the comparison will always fail.

A simple example of this is as follows using 3.10.4.

1. Download: https://developer.arm.com/-/media/Files/downloads/gnu-a/10.3-2021.07/binrel/gcc-arm-10.3-2021.07-x86_64-aarch64-none-linux-gnu.tar.xz

2. place attached python script in same directory

3. run on 3.8.2 -> fails to get stripped version of path (line 16)

4. run on 3.10.4 -> fails to get even unstripped version (line 12 & 16)

[ethanfurman]

Nosied others from bpo-21987.

[cfernald]

Introduced Pull request 32423 to resolve this issue.