If *trackfd* is False, the file descriptor specified by *fileno*
will not be duplicated.
Co-authored-by: Erlend E. Aasland <erlend@python.org>
Co-authored-by: Petr Viktorin <encukou@gmail.com>
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
Small performance improvement of getproxies_environment() when there are many environment variables. In a benchmark with 5k environment variables not related to proxies, and 5 specifying proxies, we get a 10% walltime improvement.
`PyComplex_RealAsDouble()`/`PyComplex_ImagAsDouble` now try to convert
an object to a `complex` instance using its `__complex__()` method
before falling back to the ``__float__()`` method.
PyComplex_ImagAsDouble() also will not silently return 0.0 for
non-complex types anymore. Instead we try to call PyFloat_AsDouble()
and return 0.0 only if this call is successful.
This allows users of the `pathlib-abc` PyPI package to use `posixpath` or
`ntpath` as a path module in versions of Python lacking
`os.path.splitroot()` (3.11 and before).
Path modules provide a subset of the `os.path` API, specifically those
functions needed to provide `PurePathBase` functionality. Each
`PurePathBase` subclass references its path module via a `pathmod` class
attribute.
This commit adds a new `PathModuleBase` class, which provides abstract
methods that unconditionally raise `UnsupportedOperation`. An instance of
this class is assigned to `PurePathBase.pathmod`, replacing `posixpath`.
As a result, `PurePathBase` is no longer POSIX-y by default, and
all its methods raise `UnsupportedOperation` courtesy of `pathmod`.
Users who subclass `PurePathBase` or `PathBase` should choose the path
syntax by setting `pathmod` to `posixpath`, `ntpath`, `os.path`, or their
own subclass of `PathModuleBase`, as circumstances demand.
Fix a bug in the regex used for parsing a string input to the `fractions.Fraction` constructor. That bug led to an inconsistent exception message being given for some inputs.
---------
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Mark Dickinson <dickinsm@gmail.com>
Increase the backlog for multiprocessing.connection.Listener` objects created
by `multiprocessing.manager` and `multiprocessing.resource_sharer` to
significantly reduce the risk of getting a connection refused error when creating
a `multiprocessing.connection.Connection` to them.
It's wrong for the `PurePathBase` methods to rely so much on `__str__()`.
Instead, they should treat the raw path(s) as opaque objects and leave the
details to `pathmod`.
This commit adds a `PurePathBase._raw_path` property and uses it through
many of the other ABC methods. These methods are all redefined in
`PurePath` and `Path`, so this has no effect on the public classes.
On Windows, `os.path.isabs()` now returns `False` when given a path that
starts with exactly one (back)slash. This is more compatible with other
functions in `os.path`, and with Microsoft's own documentation.
Also adjust `pathlib.PureWindowsPath.is_absolute()` to call
`ntpath.isabs()`, which corrects its handling of partial UNC/device paths
like `//foo`.
Co-authored-by: Jon Foster <jon@jon-foster.co.uk>
Make zipfile.ZipInfo.compress_level public.
A property is used to retain the behavior of the ._compresslevel.
People constructing zipfile.ZipInfo instances to pass into existing APIs to control per-file compression levels already treat this as public, there was never a reason for it not to be.
I used the more modern name compress_level instead of compresslevel as the keyword argument on other ZipFile APIs is called to be consistent with compress_type and a general long term preference of not runningwordstogether without a separator in names.
sqlite3.Connection.iterdump now ensures that foreign key support is
disabled before dumping the database schema, if there is any foreign key
violation.
Co-authored-by: Erlend E. Aasland <erlend@python.org>
test_configdialog.HighPageTest.test_highlight_target_text_mouse fails
if a line of the Highlight tab text sample is not visible. If so, bbox()
in click_char() returns None and the unpacking iteration fails.
This occurred on a Devuan Linux system. Fix by moving the
'see character' call inside click_char, just before the bbox call.
Also, reduce the click_char calls to just one per tag name and
replace the other nested function with a dict comprehension.
* improve the assert for test_one_environment_variable
* skip some test in test_subprocess when python is configured with shared
* also skip the test if AddressSanitizer is enabled
---------
Co-authored-by: Steve Dower <steve.dower@microsoft.com>
On Windows, set _O_NOINHERIT flag on file descriptors
created by os.pipe() and io.WindowsConsoleIO.
Add test_pipe_spawnl() to test_os.
Co-authored-by: Zackery Spytz <zspytz@gmail.com>
Previously the C implementation of pickle.Pickler and pickle.Unpickler
classes did not have such methods and they could only be used if
they were overloaded in subclasses or set as instance attributes.
Fixed calling super().persistent_id() and super().persistent_load() in
subclasses of the C implementation of pickle.Pickler and pickle.Unpickler
classes. It no longer causes an infinite recursion.
If other exception was raised during exiting an expired
asyncio.timeout() block, insert TimeoutError in the exception context
just above the CancelledError.
winfo_id() converts the result of "winfo id" command to integer, but
"winfo pathname" command requires an argument to be a hexadecimal number
on Win64.
When an `StopIteration` raises into `asyncio.Future`, this will cause
a thread to hang. This commit address this by not raising an exception
and silently transforming the `StopIteration` with a `RuntimeError`,
which the caller can reconstruct from `fut.exception().__cause__`
Refuse to guess what a user means when they initialise a pathlib ABC
without any positional arguments. In mainline pathlib it's normalised to
`.`, but in the ABCs this guess isn't appropriate; for example, the path
type may not represent the current directory as `.`, or may have no concept
of a "current directory" at all.
Apply pathlib's normalization and performance tuning in `pathlib.PurePath`, but not `pathlib._abc.PurePathBase`.
With this change, the pathlib ABCs do not normalize away alternate path separators, empty segments, or dot segments. A single string given to the initialiser will round-trip by default, i.e. `str(PurePathBase(my_string)) == my_string`. Implementors can set their own path domain-specific normalization scheme by overriding `__str__()`
Eliminating path normalization makes maintaining and caching the path's parts and string representation both optional and not very useful, so this commit moves the `_drv`, `_root`, `_tail_cached` and `_str` slots from `PurePathBase` to `PurePath`. Only `_raw_paths` and `_resolving` slots remain in `PurePathBase`. This frees the ABCs from the burden of some of pathlib's hardest-to-understand code.
Restore full battle-tested implementations of `PurePath.[is_]relative_to()`. These were recently split up in 3375dfe and a15a773.
In `PurePathBase`, add entirely new implementations based on `_stack`, which itself calls `pathmod.split()` repeatedly to disassemble a path. These new implementations preserve features like trailing slashes where possible, while still observing that a `..` segment cannot be added to traverse an empty or `.` segment in *walk_up* mode. They do not rely on `parents` nor `__eq__()`, nor do they spin up temporary path objects.
Unfortunately calling `pathmod.relpath()` isn't an option, as it calls `abspath()` and in turn `os.getcwd()`, which is impure.
Implement `parts` using `_stack`, which itself calls `pathmod.split()`
repeatedly. This avoids use of `_tail`, which will be moved to `PurePath`
shortly.
Test the following features for _ctypes types:
- disallow instantiation
- inheritance (MRO)
- immutability
- type name
The following _ctypes types are tested:
- Array
- CField
- COMError
- PyCArrayType
- PyCFuncPtrType
- PyCPointerType
- PyCSimpleType
- PyCStructType
- Structure
- Union
- UnionType
- _CFuncPtr
- _Pointer
- _SimpleCData
Co-authored-by: Erlend E. Aasland <erlend.aasland@protonmail.com>
Determine the support of the Kyiv timezone by checking the result of
astimezone() which uses the system tz database and not the one
populated by zoneinfo.
- Add `__slots__` to dummy path classes.
- Return namedtuple rather than `os.stat_result` from `DummyPath.stat()`.
- Reduce maximum symlink count in `DummyPathWithSymlinks.resolve()`.
`PurePathBase` does not define `__eq__()`, and so we have no business checking path equality in `test_eq_common` and `test_equivalences`. The tests only pass at the moment because we define the test class's `__eq__()` for use elsewhere.
Also move `test_parse_path_common` into the main pathlib test suite. It exercises a private `_parse_path()` method that will be moved to `PurePath` soon.
Lastly move a couple more tests concerned with optimisations and path normalisation.
It can be used to set the location of a .python_history file
---------
Co-authored-by: Levi Sabah <0xl3vi@gmail.com>
Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>
Allow extraction (no-op) of a "/" folder in a zipfile, they are commonly added by some archive creation tools.
Co-authored-by: Erlend E. Aasland <erlend@python.org>
Co-authored-by: Gregory P. Smith <greg@krypto.org>
Remove LibreSSL specific workaround ifdefs from `_ssl.c` and delete the non-version-specific `_ssl_data.h` file (relevant for OpenSSL < 1.1.1, which we no longer support per PEP 644).
Co-authored-by: Christian Heimes <christian@python.org>
Co-authored-by: Gregory P. Smith <greg@krypto.org>
Replace use of `_from_parsed_parts()` with `with_segments()` in
`PurePathBase.relative_to()`, and move the assignment of `_drv`, `_root`
and `_tail_cached` slots into `PurePath.relative_to()`.
Slightly improve `pathlib.Path.glob()` tests for symlink loop handling
When filtering results, ignore paths with more than one `linkD/` segment,
rather than all paths below the first `linkD/` segment. This allows us
to test that other paths under `linkD/` are correctly returned.
Split test cases for invalid names into dedicated test methods. This will
make it easier to refactor tests for invalid name handling in ABCs later.
No change of coverage, just a change of test suite organisation.
The `DummyPurePath` and `DummyPath` test classes are simple subclasses of
`PurePathBase` and `PathBase`. This commit adds `__repr__()` methods to the
dummy classes, which makes debugging test failures less painful.
Raise auditing events in `pathlib.Path.glob()`, `rglob()` and `walk()`,
but not in `pathlib._abc.PathBase` methods. Also move generation of a
deprecation warning into `pathlib.Path` so it gets the right stack level.
This splits part of Modules/gcmodule.c of into Python/gc.c, which
now contains the core garbage collection implementation. The Python
module remain in the Modules/gcmodule.c file.
- Only attempt to figure out whether protocol members are "method members" or not if the class is marked as a runtime protocol. This information is irrelevant for non-runtime protocols; we can safely skip the risky introspection for them.
- Only do the risky getattr() calls in one place (the runtime_checkable class decorator), rather than in three places (_ProtocolMeta.__init__, _ProtocolMeta.__instancecheck__ and _ProtocolMeta.__subclasscheck__). This reduces the number of locations in typing.py where the risky introspection could go wrong.
- For runtime protocols, if determining whether a protocol member is callable or not fails, give a better error message. I think it's reasonable for us to reject runtime protocols that have members which raise strange exceptions when you try to access them. PEP-544 clearly states that all protocol member must be callable for issubclass() calls against the protocol to be valid -- and if a member raises when we try to access it, there's no way for us to figure out whether it's a callable member or not!
* gh-53502: Fixes for tests in gh-113363
* Use 32-bit compatible date in test_dump_naive_datetime_with_aware_datetime_option
* Saving non-aware datetimes will use the old behaviour regardless of the aware_datimetime setting
The length field of StgDictObject for Structure class contains now
the total number of items in ffi_type_pointer.elements (excluding
the trailing null).
The old behavior of using the number of elements in the parent class can
cause the array to be truncated when it is copied, especially when there
are multiple layers of subclassing.
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
Run expensive tests for walking and globbing from `test_pathlib` but not
`test_pathlib_abc`. The ABCs are not as tightly optimised as the classes
in top-level `pathlib`, and so these tests are taking rather a long time on
some buildbots. Coverage of the main `pathlib` classes should suffice.
Rework error handling in the C preprocessor helper. Instead of monkey-
patching the cpp.Monitor.fail() method from within clinic.py, rewrite
cpp.py to use a subclass of the ClinicError exception. As a side-effect,
ClinicError is moved into Tools/clinic/libclinic/errors.py.
Yak-shaving in preparation for putting cpp.py into libclinic.
The `pathlib._abc` module will be made available as a PyPI backport
supporting Python 3.8+. The `warnings._deprecated()` function was only
added last year, and it's private from an external package perspective, so
here we switch to `warnings.warn()` instead.
Do not use the locale-specific default encoding in `PathBase.read_text()`
and `write_text()`. Locale settings shouldn't influence the operation of
these base classes, which are intended mostly for implementing rich paths
on *nonlocal* filesystems.
Previously some error messages complained about incompatible
combinations of directives that are not contained in the format string.
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
This fixes a divergence between the Python and C implementations of pickle
for protocol 0, such that it pickle.py fails to re-use the first pickled
representation of strings involving characters that have to be escaped.
In case the spawned process is setuid, we may not be able to send
signals to it, in which case our .kill() call will raise
PermissionError.
Ignore that in order to avoid .close() raising an exception. Hopefully
the process will exit as a result of receiving EOF on its stdin.
Move the following global helpers into libclinic:
- format_escape()
- normalize_snippet()
- wrap_declarations()
Also move strip_leading_and_trailing_blank_lines() and make it internal to libclinic.
Previously it worked differently if dst is a symbolic link:
it modified the permission bits of dst itself rather than the file
it points to if follow_symlinks is true or src is not a symbolic link,
and did nothing if follow_symlinks is false and src is a symbolic link.
Also document similar changes in shutil.copystat().
Split up clinic.py by establishing libclinic as a support package for
Argument Clinic. Get rid of clinic.py globals by either making them
class members, or by putting them into libclinic.
- Move INCLUDE_COMMENT_COLUMN to BlockPrinter
- Move NO_VARARG to CLanguage
- Move formatting helpers to libclinic
- Move some constants to libclinic (and annotate them as Final)
Replace the internal accumulator APIs by using lists of strings and join().
Yak-shaving for separating out formatting code into a separate file.
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Change the value of `pathlib._abc.PurePathBase.pathmod` from `os.path` to
`posixpath`.
User subclasses of `PurePathBase` and `PathBase` previously used the host
OS's path syntax, e.g. backslashes as separators on Windows. This is wrong
in most use cases, and likely to catch developers out unless they test on
both Windows and non-Windows machines.
In this patch we change the default to POSIX syntax, regardless of OS. This
is somewhat arguable (why not make all aspects of syntax abstract and
individually configurable?) but an improvement all the same.
This change has no effect on `PurePath`, `Path`, nor their subclasses. Only
private APIs are affected.
`PurePathBase.__repr__()` produces a string like `MyPath('/foo')`. This
repr is incorrect/misleading when a subclass's `__init__()` method is
customized, which I expect to be the very common.
This commit moves the `__repr__()` method to `PurePath`, leaving
`PurePathBase` with the default `object` repr.
No user-facing changes because the `pathlib._abc` module remains private.
* gh-109989: Fix test_c_locale_coercion when PYTHONIOENCODING is set
This fixes the existing tests when PYTHONIOENCODING is
set by unsetting PYTHONIOENCODING.
Also add a test that explicitly checks what happens
when PYTHONIOENCODING is set.
Co-authored-by: Nikita Sobolev <mail@sobolevn.me>
* Sync with importlib_metadata 7.0.0
* Add blurb
* Update docs to reflect changes.
* Link datamodel docs for object.__getitem__
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
* Add what's new for removed __getattr__
* Link datamodel docs for object.__getitem__
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
* Add exclamation point, as that seems to be used for other classes.
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
The installation of XQuartz on macOS will unconditionally
set the $DISPLAY variable. The X11 server will be launched
when a program tries to access the display. This results
in launching the X11 server when using the webbrowser module,
even though X11 browsers won't be used in practice.
The 'version' directive was introduced with gh-63929 in Nov 2013. It has
not been in use in the CPython code base, and the 'version' variable has
never been bumped.
When wrapped, `_SSLProtocolTransport._force_close(exc)` is called just like in the unwrapped scenario `_SelectorTransport._force_close(exc)` or `_ProactorBasePipeTransport._force_close(exc)` would be called, except here the exception needs to be passed through the `SSLProtocol._abort()` method, which didn't accept an exception object.
This commit ensures that this path works, in the same way that the uvloop implementation of SSLProto passes on the exception (on which the current implementation of SSLProto is based).
Change _osx_support.get_platform_osx() to make sure that the
version number in the result includes at least a major and
minor version (e.g. 14.2) even if MACOSX_DEPLOYMENT_TARGET is
set to just a major version (e.g. 14).
This matches the versions expected by pip when selecting
appropriate wheels for installation.
Add support for `os.POSIX_SPAWN_CLOSEFROM` and
`posix_spawn_file_actions_addclosefrom_np` and have the `subprocess` module use
them when available. This means `posix_spawn` can now be used in the default
`close_fds=True` situation on many platforms.
Co-authored-by: Gregory P. Smith [Google LLC] <greg@krypto.org>
* Allow posix_spawn to inherit environment form parent environ variable.
With this change, posix_spawn call can behave similarly to execv with regards to environments when used in subprocess functions.
Store the test base directory as a class attribute named `base` rather than
module constants named `BASE`.
The base directory is a local file path, and therefore not ideally suited
to the pathlib ABC tests. In a future commit we'll change its value in
`test_pathlib_abc.py` such that it points to a totally fictitious path, which
will help to ensure we're not touching the local filesystem.
PR #100161 added fancy float-style formatting for the Fraction type,
but left us in a state where basic formatting for fractions (alignment,
fill, minimum width, thousands separators) still wasn't supported.
This PR adds that support.
---------
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
Detect email address parsing errors and return empty tuple to
indicate the parsing error (old API). Add an optional 'strict'
parameter to getaddresses() and parseaddr() functions. Patch by
Thomas Dwyer.
Co-Authored-By: Thomas Dwyer <github@tomd.tel>
On Windows, Process.terminate() no longer sets the returncode
attribute to always call WaitForSingleObject() in Process.wait().
Previously, sometimes the process was still running after
TerminateProcess() even if GetExitCodeProcess() is not STILL_ACTIVE.
It was raised in two cases:
* in the import statement when looking up __import__
* in pickling some builtin type when looking up built-ins iter, getattr, etc.
This affects task creation through either `asyncio.create_task()` or `TaskGroup.create_task()` -- the redundant call to `task.set_name()` is skipped. We still call `set_name()` when a task factory is involved, because the task factory call signature (unfortunately) doesn't take a `name` argument.
We need the TracebackException of uncaught exceptions for a single purpose: the error display. Thus we only need to pass the formatted error display between interpreters. Passing a pickled TracebackException is overkill.
When an exception is uncaught in Interpreter.exec_sync(), it helps to show that exception's error display if uncaught in the calling interpreter. We do so here by generating a TracebackException in the subinterpreter and passing it between interpreters using pickle.
gh-112982 broke test_threading on one of the s390 buildbots (Fedora Clang Installed). Apparently ImportError is raised (rather than ModuleNotFoundError) for the name part of "from" imports. This fixes that by catching ImportError in test_threading.py.
Renamed re.error for clarity, and kept re.error for backward compatibility.
Updated idlelib files at TJR's request.
---------
Co-authored-by: Matthias Bussonnier <mbussonnier@ucmerced.edu>
Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>
Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
Detect Cygwin and MSYS with `uname` instead of `$OSTYPE`
`$OSTYPE` is not defined by POSIX and may not be present in other shells.
`uname` is always available in any shell.
* gh-112898: warn about unsaved files when quitting IDLE on macOS
Implement the TK function ``::tk::mac::Quit`` on macOS to
ensure that IDLE asks about saving unsaved files when
quitting IDLE.
Co-authored-by: Christopher Chavez chrischavez@gmx.us
On recentish macOS versions the system tar
command includes system metadata (ACLs, extended attributes
and resource forks) in the tar archive, which
shutil.make_archive will not do. This can cause
spurious test failures.
This was caused by 76929fdeeb, specifically its use of `super()` and its
packing/unpacking `*args`.
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Move `_PurePathBase` and `_PathBase` to a new `pathlib._abc` module, and
drop the underscores from the class names.
Tests are mostly left alone in this commit, but they'll be similarly split
in a subsequent commit.
The `pathlib._abc` module will be published as an independent PyPI package
(similar to how `zipfile._path` is published as `zipp`), to be refined
and stabilised prior to its possible addition to the standard library.
Regression test that vfork is used when expected by subprocess.
This is written integration test style, it uses strace if it is present and appears to work to find out what system call actually gets used in different scenarios.
Test coverage is added for the default behavior and that of each of the specific arguments that must disable the use of vfork. obviously not an entire test matrix, but it covers the most important aspects.
If there are ever issues with this test being flaky or failing on new platforms, rather than try and adapt it for all possible platforms, feel free to narrow the range it gets tested on when appropriate. That is not likely to reduce coverage.
Add private `pathlib._PurePathBase` class: a private superclass of both `PurePath` and `_PathBase`. Unlike `PurePath`, it does not define any of these special methods: `__fspath__`, `__bytes__`, `__reduce__`, `__hash__`, `__eq__`, `__lt__`, `__le__`, `__gt__`, `__ge__`. Its initializer and path joining methods accept only strings, not os.PathLike objects more broadly.
This is important for supporting *virtual paths*: user subclasses of `_PathBase` that provide access to archive files, FTP servers, etc. In these classes, the above methods should be implemented by users only as appropriate, with due consideration for the hash/equality of any backing objects, such as file objects or sockets.
In `test_pathlib`, the `check_drive_root_parts` test methods evaluated
both joining and parsing/normalisation of paths. This dates from a time
when pathlib implemented both functions itself, but nowadays path joining
is done with `posixpath.join()` and `ntpath.join()`.
This commit moves the joining-related test cases into `test_posixpath` and
`test_ntpath`.
If the input prompt to the builtin input function on terminal has any null
character, then raise ValueError instead of silently truncating it.
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
Use scanning "/dev/fd/" on macOS in support.fd_count(). That's both more efficient than scanning all possible file descriptors, and avoids crashing the interpreter when there are open "guarded" file descriptors.
"Guarded" file descriptors are a macOS feature where file descriptors used by system libraries are marked and cause hard crashes when used by "user" code.
Co-authored-by: Victor Stinner <vstinner@python.org>
Previously, "widget.unbind(sequence, funcid)" destroyed the current binding
for "sequence", leaving "sequence" unbound, and deleted the "funcid"
command.
Now it removes only "funcid" from the binding for "sequence", keeping
other commands, and deletes the "funcid" command.
It leaves "sequence" unbound only if "funcid" was the last bound command.
Co-authored-by: GiovanniL <13402461+GiovaLomba@users.noreply.github.com>
* Implement _Py_HashPointerRaw() as a static inline function.
* Add Py_HashPointer() tests to test_capi.test_hash.
* Keep _Py_HashPointer() function as an alias to Py_HashPointer().
* Ignore os.close() errors when ignore_errors is True.
* Pass os.close() errors to the error handler if specified.
* os.close no longer retried after error.
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
Previously a symlink attack resistant version of shutil.rmtree() could ignore
or pass to the error handler arbitrary exception when invalid arguments
were provided.
Set MAX_STRUCT_SIZE to 32 in stgdict.c when on Arm platforms.
This because on Arm platforms structs with at most 4 elements of any
floating point type values can be passed through registers. If the type
is double the maximum size of the struct is 32 bytes.
On x86-64 Linux, it's maximum 16 bytes hence we need to differentiate.
Add a track parameter to shared memory to allow resource tracking via the side-launched resource tracker process to be disabled on platforms that use it (POSIX).
This allows people who do not want automated cleanup at process exit because they are using the shared memory with processes not participating in Python's resource tracking to use the shared_memory API.
Co-authored-by: Łukasz Langa <lukasz@langa.pl>
Co-authored-by: Guido van Rossum <gvanrossum@gmail.com>
Co-authored-by: Antoine Pitrou <pitrou@free.fr>
Co-authored-by: Gregory P. Smith <greg@krypto.org>
Refactor delete-safe symbol handling in subprocess.
Only module globals are force-cleared during interpreter finalization, using a class reference instead of individually listing the constants everywhere is simpler.
Use `_from_parsed_parts()` to create a pre-joined/pre-parsed path, rather
than passing multiple arguments to `with_segments()`
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Restore `subprocess`'s intended use of `vfork()` by default for performance on Linux;
also fixes the behavior of `extra_groups=[]` which was unintentionally broken in 3.12.0:
Fixed a performance regression in 3.12's :mod:`subprocess` on Linux where it
would no longer use the fast-path ``vfork()`` system call when it could have
due to a logic bug, instead falling back to the safe but slower ``fork()``.
Also fixed a security bug introduced in 3.12.0. If a value of ``extra_groups=[]``
was passed to :mod:`subprocess.Popen` or related APIs, the underlying
``setgroups(0, NULL)`` system call to clear the groups list would not be made
in the child process prior to ``exec()``.
The security issue was identified via code inspection in the process of
fixing the first bug. Thanks to @vain for the detailed report and
analysis in the initial bug on Github.
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
