infinite loop after pip install on Android API 24

[xdegaye]

• Pip version: 9.0.1
• Python version: 3.8 (current master branch)
• Operating system: Android 7.0 (API 24)

Description:

After a successfull install of a first package (pygeodesy) pip never exits and must be interrupted with ^C.

What I've run:

$ python -m ensurepip --upgrade --default-pip
$ pip install pygeodesy
^CTraceback (most recent call last):
  File "/data/data/com.termux/files/usr/local/lib/python3.8/site-packages/pip/_vendor/lockfile/linklockfile.py", line 31, in acquire
    os.link(self.unique_name, self.lock_file)
PermissionError: [Errno 13] Permission denied: '/data/data/com.termux/files/home/.cache/pip/localhost-7f1b3a98.201375002993129885618981' -> '/data/data/com.termux/files/home/.cache/pip/selfcheck.json.lock'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/data/data/com.termux/files/usr/local/bin/pip", line 11, in <module>
    sys.exit(main())
  File "/data/data/com.termux/files/usr/local/lib/python3.8/site-packages/pip/__init__.py", line 233, in main
    return command.main(cmd_args)
  File "/data/data/com.termux/files/usr/local/lib/python3.8/site-packages/pip/basecommand.py", line 252, in main
    pip_version_check(session)
  File "/data/data/com.termux/files/usr/local/lib/python3.8/site-packages/pip/utils/outdated.py", line 138, in pip_version_check
    state.save(pypi_version, current_time)
  File "/data/data/com.termux/files/usr/local/lib/python3.8/site-packages/pip/utils/outdated.py", line 71, in save
    with lockfile.LockFile(self.statefile_path):
  File "/data/data/com.termux/files/usr/local/lib/python3.8/site-packages/pip/_vendor/lockfile/__init__.py", line 197, in __enter__
    self.acquire()
  File "/data/data/com.termux/files/usr/local/lib/python3.8/site-packages/pip/_vendor/lockfile/linklockfile.py", line 50, in acquire
    time.sleep(timeout is not None and timeout / 10 or 0.1)
KeyboardInterrupt

[xdegaye]

On Android API 24 and more recent versions, hard links are not allowed by the SELinux policies set by Android except for privileged users (i.e. root), see https://bugs.python.org/issue28759.

LinkLockFile.acquire() in pip/_vendor/lockfile/linklockfile.py runs with timeout as None, hence the infinite loop.

[pradyunsg]

Hi @xdegaye! Thanks for filing this issue. :)

I don't think pip directly supports either Python 3.8 (the in-development version) or Android.

That said, this issue stems from a vendored dependency (lockfile) and the issue should be fixed there. Note that we're looking into alternatives to lockfile (#4766), which would likely also fix this problem.

[xdegaye]

@pradyunsg

I don't think pip directly supports either Python 3.8 (the in-development version) or Android.

FWIW it is possible to install Python 3.6 on Android with termux on Android API 24 (i.e. Android 7.0 Nougat) and to install Python packages with pip.

[xdegaye]

@pradyunsg

That said, this issue stems from a vendored dependency (lockfile) and the issue should be fixed there

The LinkLockFile.acquire() method in linklockfile.py loops infinitely when the following conditions are met:

• self.timeout is None
• acquire() is not called with the timeout key word argument, or it is set to None
• os.link() fails with PermissionError or any other permanent condition

The issue does stem from the implementation of this method.

[cjerdonek]

It looks like that code should be letting PermissionErrors bubble up, which is similar to the issue with #6169.

[chrahunt]

I have created #6954 to consolidate these issues, let's track it there.