python / cpython

…and 1 (GH-22870)

…2944)

Using POSIX_CALL() is incorrect since pthread_sigmask() returns
the error number instead of setting errno.

Also handle failure of the first call to pthread_sigmask()
in the parent process, and explain why we don't handle failure
of the second call in a comment.

…H-22927)

Closes python/bedevere#287

…ned up (GH-22931)

Automerge-Triggered-By: GH:brettcannon

…fe (GH-11671)

* bpo-35823: subprocess: Use vfork() instead of fork() on Linux when safe

When used to run a new executable image, fork() is not a good choice
for process creation, especially if the parent has a large working set:
fork() needs to copy page tables, which is slow, and may fail on systems
where overcommit is disabled, despite that the child is not going to
touch most of its address space.

Currently, subprocess is capable of using posix_spawn() instead, which
normally provides much better performance. However, posix_spawn() does not
support many of child setup operations exposed by subprocess.Popen().
Most notably, it's not possible to express `close_fds=True`, which
happens to be the default, via posix_spawn(). As a result, most users
can't benefit from faster process creation, at least not without
changing their code.

However, Linux provides vfork() system call, which creates a new process
without copying the address space of the parent, and which is actually
used by C libraries to efficiently implement posix_spawn(). Due to sharing
of the address space and even the stack with the parent, extreme care
is required to use vfork(). At least the following restrictions must hold:

* No signal handlers must execute in the child process. Otherwise, they
  might clobber memory shared with the parent, potentially confusing it.

* Any library function called after vfork() in the child must be
  async-signal-safe (as for fork()), but it must also not interact with any
  library state in a way that might break due to address space sharing
  and/or lack of any preparations performed by libraries on normal fork().
  POSIX.1 permits to call only execve() and _exit(), and later revisions
  remove vfork() specification entirely. In practice, however, almost all
  operations needed by subprocess.Popen() can be safely implemented on
  Linux.

* Due to sharing of the stack with the parent, the child must be careful
  not to clobber local variables that are alive across vfork() call.
  Compilers are normally aware of this and take extra care with vfork()
  (and setjmp(), which has a similar problem).

* In case the parent is privileged, special attention must be paid to vfork()
  use, because sharing an address space across different privilege domains
  is insecure[1].

This patch adds support for using vfork() instead of fork() on Linux
when it's possible to do safely given the above. In particular:

* vfork() is not used if credential switch is requested. The reverse case
  (simple subprocess.Popen() but another application thread switches
  credentials concurrently) is not possible for pure-Python apps because
  subprocess.Popen() and functions like os.setuid() are mutually excluded
  via GIL. We might also consider to add a way to opt-out of vfork() (and
  posix_spawn() on platforms where it might be implemented via vfork()) in
  a future PR.

* vfork() is not used if `preexec_fn != None`.

With this change, subprocess will still use posix_spawn() if possible, but
will fallback to vfork() on Linux in most cases, and, failing that,
to fork().

[1] https://ewontfix.com/7

Co-authored-by: Gregory P. Smith [Google LLC] <gps@google.com>

Add support for HTTP Only flag in MozillaCookieJar

Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from v1 to v2.2.0.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/actions/upload-artifact/releases">actions/upload-artifact's releases</a>.</em></p>
<blockquote>
<h2>v2.2.0</h2>
<ul>
<li>Support for artifact retention</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/actions/upload-artifact/commit/27bce4eee761b5bc643f46a8dfb41b430c8d05f6"><code>27bce4e</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/actions/upload-artifact/issues/112">#112</a> from thboop/main</li>
<li><a href="https://github.com/actions/upload-artifact/commit/f8b42f7ab442a66b3d51a5ca02855b194a36ae2d"><code>f8b42f7</code></a> update licensed files</li>
<li><a href="https://github.com/actions/upload-artifact/commit/2106e8cf10e032ca9d5724c4c676543febe74f0b"><code>2106e8c</code></a> update contributing.md</li>
<li><a href="https://github.com/actions/upload-artifact/commit/db66798ebcfbaa7f3f8ff66bce013213265c30d1"><code>db66798</code></a> Ignore Generated Files in Git PR's</li>
<li><a href="https://github.com/actions/upload-artifact/commit/d359fd0772ed6802a84728dd6b09ec99f41a67b7"><code>d359fd0</code></a> Manual Verification of licenses</li>
<li><a href="https://github.com/actions/upload-artifact/commit/350822c32f871c559dbe1667c24424e06c4f03e3"><code>350822c</code></a> Add Licensed Workflow and config</li>
<li><a href="https://github.com/actions/upload-artifact/commit/abecf4abf4b70bc636949d61150be883b87416c2"><code>abecf4a</code></a> Updated README.md (<a href="https://github-redirect.dependabot.com/actions/upload-artifact/issues/118">#118</a>)</li>
<li><a href="https://github.com/actions/upload-artifact/commit/604e071d21906545dedcfaf210deae74f8c5276a"><code>604e071</code></a> Merge pull request <a href="https://github-redirect.dependabot.com/actions/upload-artifact/issues/126">#126</a> from yacaovsnc/main</li>
<li><a href="https://github.com/actions/upload-artifact/commit/4560c23b396d494f0cb7066e1d6e258e8feb8051"><code>4560c23</code></a> Check for invalid retention-days input</li>
<li><a href="https://github.com/actions/upload-artifact/commit/59018c2f85dd0e101b75544aa87f13bb0c94e0b7"><code>59018c2</code></a> Add an option to specify retention period</li>
<li>Additional commits viewable in <a href="https://github.com/actions/upload-artifact/compare/v1...27bce4eee761b5bc643f46a8dfb41b430c8d05f6">compare view</a></li>
</ul>
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Automerge-Triggered-By: GH:Mariatta

Bumps [actions/cache](https://github.com/actions/cache) from v1 to v2.1.2.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/actions/cache/releases">actions/cache's releases</a>.</em></p>
<blockquote>
<h2>v2.1.2</h2>
<ul>
<li>Adds input to limit the chunk upload size, useful for self-hosted runners with slower upload speeds</li>
<li>No-op when executing on GHES</li>
</ul>
</blockquote>
</details>
<details>
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<li><a href="https://github.com/actions/cache/commit/68cfb2ccb73b1982be3fa55e3d7c842697d7f1ed"><code>68cfb2c</code></a> Add units to description</li>
<li><a href="https://github.com/actions/cache/commit/cce3c03a74623545a53c433d301f3f7725c72454"><code>cce3c03</code></a> Add new input to action.yml</li>
<li><a href="https://github.com/actions/cache/commit/4bceb75b5b7743784c63c94b81c50a485cbdcda0"><code>4bceb75</code></a> Use parseInt instead of Number to handle empty strings</li>
<li><a href="https://github.com/actions/cache/commit/a6f1f4b32eec85780fedc5b354a583e9b2999100"><code>a6f1f4b</code></a> Adds input for upload chunk size</li>
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<li><a href="https://github.com/actions/cache/commit/d3e4f218f30bd71a2c29e2b2a1e4f811f4327162"><code>d3e4f21</code></a> Use warning instead of info</li>
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Automerge-Triggered-By: GH:Mariatta

Let Dependabot update GitHub Actions dependency once a month.

Here's reference to the dependabot configs.

https://docs.github.com/en/free-pro-team@latest/github/administering-a-repository/keeping-your-actions-up-to-date-with-github-dependabot

Sponsor Python on GitHub

… char in PATHEXT (GH-20088)

shutil.which will not return None anymore for empty str in PATHEXT
Empty PATHEXT will now be defaulted to _WIN_DEFAULT_PATHEXT

The original tool wasn't working right and it was simpler to create a new one, partially re-using some of the old code. At this point the tool runs properly on the master. (Try: ./python Tools/c-analyzer/c-analyzer.py analyze.)  It take ~40 seconds on my machine to analyze the full CPython code base.

Note that we'll need to iron out some OS-specific stuff (e.g. preprocessor). We're okay though since this tool isn't used yet in our workflow. We will also need to verify the analysis results in detail before activating the check in CI, though I'm pretty sure it's close.

https://bugs.python.org/issue36876

)

Automerge-Triggered-By: GH:gvanrossum

Add documentation to help diagnose CDLL dependent DLL loading errors
on windows for OSError with message:
"[WinError 126] The specified module could not be found"
This error is otherwise difficult to diagnose.

Commit 1d541c2 introduced a NULL
pointer dereference in error path.

Signed-off-by: Christian Heimes <christian@python.org>

This is just test code, but sometimes external contributors reference the code snippets from test code.
`PyModule_AddObject` should be handled in the proper way.

https://docs.python.org/3/c-api/module.html#c.PyModule_AddObject

…bject.__ne__ (GH-22874)

See Objects/typeobject.c:object_richcompare() for the implementation of this in CPython.

Automerge-Triggered-By: GH:brettcannon

…ations (GH-22862)

…GH-15190)

@ericsnowcurrently This PR will change the following:

In the library documentation importlib.rst:

- `module.__package__` can be `module.__name__` for packages;
- `spec.parent` can be `spec.__name__` for packages;
- `spec.loader` is not `None` for namespaces packages.

In the language documentation import.rst:

- `spec.loader` is not `None` for namespace packages.

Automerge-Triggered-By: GH:warsaw

… class name (GH-22867)

This is a trivial fix to [bpo-39416](), which didn't come up until it was already committed

```
Change "Numeric" to "numeric".

I believe this is trivial enough to not need an issue or a NEWS entry, although
I'm unclear on what branches the original pull request received backports.
```

Automerge-Triggered-By: GH:merwok

…H-22864)

GH-22580)

While translating the following document to Spanish we found there is a grammar issue on the original documentation.

…ations of numeric classes (GH-18111)

[bpo-39416](): Document string representations of the Numeric classes

This is a change to the specification of the Python language.

The idea here is to put sane minimal limits on the Python language's default
representations of its Numeric classes.  That way "Marty's Robotic Massage Parlor
and Python Interpreter" implementation of Python won't do anything too
crazy.

Some discussion in the email thread:
Subject: Documenting Python's float.__str__()
https://mail.python.org/archives/list/python-dev@python.org/thread/FV22TKT3S2Q3P7PNN6MCXI6IX3HRRNAL/