gh-81793: Always call linkat() from os.link(), if available by serhiy-storchaka · Pull Request #132517 · python/cpython

serhiy-storchaka · 2025-04-14T14:53:11Z

This fixes os.link() on platforms (like Linux and OpenIndiana) where the system link() function does not follow symlinks.

On Linux ~~and OpenIndiana~~, it now follows symlinks by default or if follow_symlinks=True is specified.
On Windows, it now raises error if follow_symlinks=True is passed.
On macOS, it now raises error if follow_symlinks=False is passed and the system linkat() function is not available at runtime.
On other platforms, it now raises error if follow_symlinks is passed with a value that does not match the system link() function behavior if if the behavior is not known.

Issue: os.link(..., follow_symlinks=True) broken on Linux #81793

📚 Documentation preview 📚: https://cpython-previews--132517.org.readthedocs.build/

This fixes os.link() on platforms (like Linux and OpenIndiana) where the system link() function does not follow symlinks. * On Linux and OpenIndiana, it now follows symlinks by default and if follow_symlinks=True is specified. * On Windows, it now raises error if follow_symlinks=True is passed. * On macOS, it now raises error if follow_symlinks=False is passed and the system linkat() function is not available at runtime. * On other platforms, it now raises error if follow_symlinks is passed with a value that does not match the system link() function behavior if if the behavior is not known. Co-authored-by: Joachim Henke <37883863+jo-he@users.noreply.github.com> Co-authored-by: Thomas Kluyver <takowl@gmail.com>

Misc/NEWS.d/next/Library/2025-04-14-17-24-50.gh-issue-81793.OhRTTT.rst

Modules/posixmodule.c

Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>

serhiy-storchaka

Thank you for grammar fixes @StanFromIreland.

Misc/NEWS.d/next/Library/2025-04-14-17-24-50.gh-issue-81793.OhRTTT.rst

StanFromIreland · 2025-04-14T18:05:56Z

No problem:-)

This reverts commit a45dfd9.

bedevere-bot · 2025-05-04T14:45:52Z

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot aarch64 Android 3.x (tier-3) has failed when building commit 5a57248.

What do you need to do:

Don't panic.
Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1594/builds/2228) and take a look at the build logs.
Check if the failure is related to this commit (5a57248) or if it is a false positive.
If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1594/builds/2228

Failed tests:

test_posix

Failed subtests:

test_link_follow_symlinks - test.test_posix.PosixTester.test_link_follow_symlinks

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/data/user/0/org.python.testbed/files/python/lib/python3.14/test/test_posix.py", line 1548, in test_link_follow_symlinks
    posix.link(symlink, link, follow_symlinks=False)
    ~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
PermissionError: [Errno 13] Permission denied: '@test_1785_tmpæsymlink' -> '@test_1785_tmpælink_nofollow'


Traceback (most recent call last):
  File "/data/user/0/org.python.testbed/files/python/lib/python3.14/test/test_posix.py", line 1560, in test_link_follow_symlinks
    posix.link(symlink, link, follow_symlinks=True)
    ~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
PermissionError: [Errno 13] Permission denied: '@test_1785_tmpæsymlink' -> '@test_1785_tmpælink_following'


Traceback (most recent call last):
  File "/data/user/0/org.python.testbed/files/python/lib/python3.14/test/test_posix.py", line 1537, in test_link_follow_symlinks
    posix.link(symlink, link)
    ~~~~~~~~~~^^^^^^^^^^^^^^^
PermissionError: [Errno 13] Permission denied: '@test_1785_tmpæsymlink' -> '@test_1785_tmpælink'

* origin/main: (111 commits) pythongh-91048: Add filename and line number to external inspection routines (pythonGH-133385) pythongh-131178: Add tests for `ast` command-line interface (python#133329) Regenerate pcbuild.sln in Visual Studio 2022 (python#133394) pythongh-133042: disable HACL* HMAC on Emscripten (python#133064) pythongh-133351: Fix remote PDB's multi-line block tab completion (python#133387) pythongh-109700: Improve stress tests for interpreter creation (pythonGH-109946) pythongh-81793: Skip tests for os.link() to symlink on Android (pythonGH-133388) pythongh-126835: Rename `ast_opt.c` to `ast_preprocess.c` and related stuff after moving const folding to the peephole optimizier (python#131830) pythongh-91048: Relax test_async_global_awaited_by to fix flakyness (python#133368) pythongh-132457: make staticmethod and classmethod generic (python#132460) pythongh-132805: annotationlib: Fix handling of non-constant values in FORWARDREF (python#132812) pythongh-132426: Add get_annotate_from_class_namespace replacing get_annotate_function (python#132490) pythongh-81793: Always call linkat() from os.link(), if available (pythonGH-132517) pythongh-122559: Synchronize C and Python implementation of the io module about pickling (pythonGH-122628) pythongh-69605: Add PyREPL import autocomplete feature to 'What's New' (python#133358) bpo-44172: Keep reference to original window in curses subwindow objects (pythonGH-26226) pythonGH-133231: Changes to executor management to support proposed `sys._jit` module (pythonGH-133287) pythongh-133363: Fix Cmd completion for lines beginning with `! ` (python#133364) pythongh-132983: Introduce `_zstd` bindings module (pythonGH-133027) pythonGH-91048: Add utils for printing the call stack for asyncio tasks (python#133284) ...

freakboy3742 · 2025-05-06T04:23:41Z

Not sure of the source of the Android failure here, but it looks related to the subject ticket. Investigation ongoing.

serhiy-storchaka · 2025-05-06T05:59:56Z

It was fixed on #133388.

freakboy3742 · 2025-05-06T06:18:36Z

It was fixed on #133388.

Thanks for the fast response!

…thonGH-132517) This fixes os.link() on platforms (like Linux and OpenIndiana) where the system link() function does not follow symlinks. * On Linux, it now follows symlinks by default and if follow_symlinks=True is specified. * On Windows, it now raises error if follow_symlinks=True is passed. * On macOS, it now raises error if follow_symlinks=False is passed and the system linkat() function is not available at runtime. * On other platforms, it now raises error if follow_symlinks is passed with a value that does not match the system link() function behavior if if the behavior is not known. Co-authored-by: Joachim Henke <37883863+jo-he@users.noreply.github.com> Co-authored-by: Thomas Kluyver <takowl@gmail.com>

bedevere-app bot added the awaiting core review label Apr 14, 2025

bedevere-app bot mentioned this pull request Apr 14, 2025

os.link(..., follow_symlinks=True) broken on Linux #81793

Closed

serhiy-storchaka added 4 commits April 14, 2025 18:05

Fix typo and regenerate clinic files.

4ba224e

Fix OpenIndiana.

5881b2a

Fix test_inspect.

d2f233b

Enable linkat().

95f55e3

StanFromIreland reviewed Apr 14, 2025

View reviewed changes

Apply suggestions from code review

2eeb438

Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>

serhiy-storchaka commented Apr 14, 2025

View reviewed changes

Misc/NEWS.d/next/Library/2025-04-14-17-24-50.gh-issue-81793.OhRTTT.rst Outdated Show resolved Hide resolved

serhiy-storchaka added 7 commits April 15, 2025 10:03

Use subTest().

b4be526

Disable linkat() on WASI.

80128e3

Test how link() actually works on WASI.

a45dfd9

Revert "Test how link() actually works on WASI."

557f1ee

This reverts commit a45dfd9.

Merge branch 'main' into os-link-follow_symlinks

b156f94

Remove redundant checks for same type.

2c436fb

Merge branch 'main' into os-link-follow_symlinks

0c7b16d

serhiy-storchaka merged commit 5a57248 into python:main May 4, 2025
42 checks passed

bedevere-app bot removed the awaiting core review label May 4, 2025

serhiy-storchaka deleted the os-link-follow_symlinks branch May 4, 2025 14:24

This was referenced May 4, 2025

bpo-37612: always call linkat() from os.link(), if available #14843

Closed

gh-81793: always call linkat() from os.link(), if available #24997

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gh-81793: Always call linkat() from os.link(), if available#132517

gh-81793: Always call linkat() from os.link(), if available#132517
serhiy-storchaka merged 13 commits intopython:mainfrom
serhiy-storchaka:os-link-follow_symlinks

serhiy-storchaka commented Apr 14, 2025 •

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⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

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