# Copyright (c) 2009, Giampaolo Rodola'. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Test utilities."""

import atexit
import contextlib
import ctypes
import enum
import errno
import functools
import importlib
import ipaddress
import os
import platform
import random
import re
import select
import shlex
import shutil
import signal
import socket
import stat
import subprocess
import sys
import tempfile
import textwrap
import threading
import time
import traceback
import unittest
import warnings
from socket import AF_INET
from socket import AF_INET6
from socket import SOCK_STREAM

try:
    import pytest
except ImportError:
    pytest = None

import psutil
from psutil import AIX
from psutil import LINUX
from psutil import MACOS
from psutil import NETBSD
from psutil import OPENBSD
from psutil import POSIX
from psutil import SUNOS
from psutil import WINDOWS
from psutil._common import debug
from psutil._common import memoize
from psutil._common import supports_ipv6

if POSIX:
    from psutil._psposix import wait_pid


# fmt: off
__all__ = [
    # constants
    'DEVNULL', 'GLOBAL_TIMEOUT', 'TOLERANCE_SYS_MEM', 'NO_RETRIES',
    'PYPY', 'PYTHON_EXE', 'PYTHON_EXE_ENV', 'ROOT_DIR', 'SCRIPTS_DIR',
    'TESTFN_PREFIX', 'UNICODE_SUFFIX', 'INVALID_UNICODE_SUFFIX',
    'CI_TESTING', 'VALID_PROC_STATUSES', 'TOLERANCE_DISK_USAGE', 'IS_64BIT',
    "HAS_CPU_AFFINITY", "HAS_CPU_FREQ", "HAS_ENVIRON", "HAS_PROC_IO_COUNTERS",
    "HAS_IONICE", "HAS_MEMORY_MAPS", "HAS_PROC_CPU_NUM", "HAS_RLIMIT",
    "HAS_SENSORS_BATTERY", "HAS_BATTERY", "HAS_SENSORS_FANS",
    "HAS_SENSORS_TEMPERATURES", "HAS_NET_CONNECTIONS_UNIX", "MACOS_11PLUS",
    "MACOS_12PLUS", "COVERAGE", 'AARCH64', "PYTEST_PARALLEL",
    # subprocesses
    'pyrun', 'terminate', 'reap_children', 'spawn_subproc', 'spawn_zombie',
    'spawn_children_pair',
    # threads
    'ThreadTask',
    # test utils
    'unittest', 'skip_on_access_denied', 'skip_on_not_implemented',
    'retry_on_failure', 'PsutilTestCase', 'process_namespace',
    'system_namespace',
    'is_win_secure_system_proc',
    # fs utils
    'chdir', 'safe_rmpath', 'create_py_exe', 'create_c_exe', 'get_testfn',
    # os
    'get_winver', 'kernel_version',
    # sync primitives
    'call_until', 'wait_for_pid', 'wait_for_file',
    # network
    'check_net_address', 'filter_proc_net_connections',
    'get_free_port', 'bind_socket', 'bind_unix_socket', 'tcp_socketpair',
    'unix_socketpair', 'create_sockets',
    # compat
    'reload_module', 'import_module_by_path',
    # others
    'warn', 'copyload_shared_lib', 'is_namedtuple'
]
# fmt: on


# ===================================================================
# --- constants
# ===================================================================

# --- platforms

PYPY = '__pypy__' in sys.builtin_module_names
# whether we're running this test suite on a Continuous Integration service
GITHUB_ACTIONS = 'GITHUB_ACTIONS' in os.environ or 'CIBUILDWHEEL' in os.environ
CI_TESTING = GITHUB_ACTIONS
COVERAGE = 'COVERAGE_RUN' in os.environ
PYTEST_PARALLEL = "PYTEST_XDIST_WORKER" in os.environ  # `make test-parallel`
# are we a 64 bit process?
IS_64BIT = sys.maxsize > 2**32
# apparently they're the same
AARCH64 = platform.machine().lower() in {"aarch64", "arm64"}
RISCV64 = platform.machine() == "riscv64"


@memoize
def macos_version():
    version_str = platform.mac_ver()[0]
    version = tuple(map(int, version_str.split(".")[:2]))
    if version == (10, 16):
        # When built against an older macOS SDK, Python will report
        # macOS 10.16 instead of the real version.
        version_str = subprocess.check_output(
            [
                sys.executable,
                "-sS",
                "-c",
                "import platform; print(platform.mac_ver()[0])",
            ],
            env={"SYSTEM_VERSION_COMPAT": "0"},
            universal_newlines=True,
        )
        version = tuple(map(int, version_str.split(".")[:2]))
    return version


if MACOS:
    MACOS_11PLUS = macos_version() > (10, 15)
    MACOS_12PLUS = macos_version() >= (12, 0)
else:
    MACOS_11PLUS = False
    MACOS_12PLUS = False


# --- configurable defaults

# how many times retry_on_failure() decorator will retry
NO_RETRIES = 10
# bytes tolerance for system-wide related tests
TOLERANCE_SYS_MEM = 5 * 1024 * 1024  # 5MB
TOLERANCE_DISK_USAGE = 10 * 1024 * 1024  # 10MB
# the timeout used in functions which have to wait
GLOBAL_TIMEOUT = 5
# be more tolerant if we're on CI in order to avoid false positives
if CI_TESTING:
    NO_RETRIES *= 3
    GLOBAL_TIMEOUT *= 3
    TOLERANCE_SYS_MEM *= 4
    TOLERANCE_DISK_USAGE *= 3

# --- file names

# Disambiguate TESTFN with PID for parallel testing.
TESTFN_PREFIX = f"@psutil-{os.getpid()}-"
UNICODE_SUFFIX = "-ƒőő"
# An invalid unicode string.
INVALID_UNICODE_SUFFIX = b"f\xc0\x80".decode('utf8', 'surrogateescape')
ASCII_FS = sys.getfilesystemencoding().lower() in {"ascii", "us-ascii"}

# --- paths

ROOT_DIR = os.environ.get("PSUTIL_ROOT_DIR") or os.path.realpath(
    os.path.join(os.path.dirname(__file__), "..")
)
SCRIPTS_DIR = os.path.join(ROOT_DIR, 'scripts')
HERE = os.path.realpath(os.path.dirname(__file__))

# --- support

HAS_CPU_AFFINITY = hasattr(psutil.Process, "cpu_affinity")
HAS_ENVIRON = hasattr(psutil.Process, "environ")
HAS_GETLOADAVG = hasattr(psutil, "getloadavg")
HAS_IONICE = hasattr(psutil.Process, "ionice")
HAS_HEAP_INFO = hasattr(psutil, "heap_info")
HAS_MEMORY_MAPS = hasattr(psutil.Process, "memory_maps")
HAS_NET_CONNECTIONS_UNIX = POSIX and not SUNOS
HAS_NET_IO_COUNTERS = hasattr(psutil, "net_io_counters")
HAS_PROC_CPU_NUM = hasattr(psutil.Process, "cpu_num")
HAS_PROC_IO_COUNTERS = hasattr(psutil.Process, "io_counters")
HAS_RLIMIT = hasattr(psutil.Process, "rlimit")
HAS_SENSORS_BATTERY = hasattr(psutil, "sensors_battery")
HAS_SENSORS_FANS = hasattr(psutil, "sensors_fans")
HAS_SENSORS_TEMPERATURES = hasattr(psutil, "sensors_temperatures")
HAS_THREADS = hasattr(psutil.Process, "threads")
SKIP_SYSCONS = (MACOS or AIX) and os.getuid() != 0

try:
    HAS_BATTERY = HAS_SENSORS_BATTERY and bool(psutil.sensors_battery())
except Exception:  # noqa: BLE001
    atexit.register(functools.partial(print, traceback.format_exc()))
    HAS_BATTERY = False
try:
    HAS_CPU_FREQ = hasattr(psutil, "cpu_freq") and bool(psutil.cpu_freq())
except Exception:  # noqa: BLE001
    atexit.register(functools.partial(print, traceback.format_exc()))
    HAS_CPU_FREQ = False


# --- misc


def _get_py_exe():
    def attempt(exe):
        try:
            subprocess.check_call(
                [exe, "-V"], stdout=subprocess.PIPE, stderr=subprocess.PIPE
            )
        except subprocess.CalledProcessError:
            return None
        else:
            return exe

    env = os.environ.copy()

    # On Windows, starting with python 3.7, virtual environments use a
    # venv launcher startup process. This does not play well when
    # counting spawned processes, or when relying on the PID of the
    # spawned process to do some checks, e.g. connections check per PID.
    # Let's use the base python in this case.
    base = getattr(sys, "_base_executable", None)
    if WINDOWS and sys.version_info >= (3, 7) and base is not None:
        # We need to set __PYVENV_LAUNCHER__ to sys.executable for the
        # base python executable to know about the environment.
        env["__PYVENV_LAUNCHER__"] = sys.executable
        return base, env
    elif GITHUB_ACTIONS:
        return sys.executable, env
    elif MACOS:
        exe = (
            attempt(sys.executable)
            or attempt(os.path.realpath(sys.executable))
            or attempt(
                shutil.which("python{}.{}".format(*sys.version_info[:2]))
            )
            or attempt(psutil.Process().exe())
        )
        if not exe:
            raise ValueError("can't find python exe real abspath")
        return exe, env
    else:
        exe = os.path.realpath(sys.executable)
        assert os.path.exists(exe), exe
        return exe, env


PYTHON_EXE, PYTHON_EXE_ENV = _get_py_exe()
DEVNULL = open(os.devnull, 'r+')  # noqa: SIM115
atexit.register(DEVNULL.close)

VALID_PROC_STATUSES = [
    getattr(psutil, x) for x in dir(psutil) if x.startswith('STATUS_')
]
AF_UNIX = getattr(socket, "AF_UNIX", object())

_subprocesses_started = set()
_pids_started = set()


# ===================================================================
# --- threads
# ===================================================================


class ThreadTask(threading.Thread):
    """A thread task which does nothing expect staying alive."""

    def __init__(self):
        super().__init__()
        self._running = False
        self._interval = 0.001
        self._flag = threading.Event()

    def __repr__(self):
        name = self.__class__.__name__
        return f"<{name} running={self._running} at {id(self):#x}>"

    def __enter__(self):
        self.start()
        return self

    def __exit__(self, *args, **kwargs):
        self.stop()

    def start(self):
        """Start thread and keep it running until an explicit
        stop() request. Polls for shutdown every 'timeout' seconds.
        """
        if self._running:
            raise ValueError("already started")
        threading.Thread.start(self)
        self._flag.wait()

    def run(self):
        self._running = True
        self._flag.set()
        while self._running:
            time.sleep(self._interval)

    def stop(self):
        """Stop thread execution and and waits until it is stopped."""
        if not self._running:
            raise ValueError("already stopped")
        self._running = False
        self.join()


# ===================================================================
# --- subprocesses
# ===================================================================


def _reap_children_on_err(fun):
    @functools.wraps(fun)
    def wrapper(*args, **kwargs):
        try:
            return fun(*args, **kwargs)
        except Exception:
            reap_children()
            raise

    return wrapper


@_reap_children_on_err
def spawn_subproc(cmd=None, **kwds):
    """Create a python subprocess which does nothing for some secs and
    return it as a subprocess.Popen instance.
    If "cmd" is specified that is used instead of python.
    By default stdin and stdout are redirected to /dev/null.
    It also attempts to make sure the process is in a reasonably
    initialized state.
    The process is registered for cleanup on reap_children().
    """
    kwds.setdefault("stdin", DEVNULL)
    kwds.setdefault("stdout", DEVNULL)
    kwds.setdefault("cwd", os.getcwd())
    kwds.setdefault("env", PYTHON_EXE_ENV)
    if WINDOWS:
        # Prevents the subprocess to open error dialogs. This will also
        # cause stderr to be suppressed, which is suboptimal in order
        # to debug broken tests.
        # CREATE_NO_WINDOW = 0x8000000
        # kwds.setdefault("creationflags", CREATE_NO_WINDOW)

        # New: hopefully this should achieve the same and not suppress
        # stderr.
        startupinfo = subprocess.STARTUPINFO()
        startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
        startupinfo.wShowWindow = subprocess.SW_HIDE
        kwds.setdefault("startupinfo", startupinfo)

    if cmd is None:
        testfn = get_testfn(dir=os.getcwd())
        try:
            safe_rmpath(testfn)
            pyline = (
                "import time;"
                f"open(r'{testfn}', 'w').close();"
                "[time.sleep(0.1) for x in range(100)];"  # 10 secs
            )
            cmd = [PYTHON_EXE, "-c", pyline]
            sproc = subprocess.Popen(cmd, **kwds)
            _subprocesses_started.add(sproc)
            wait_for_file(testfn, delete=True, empty=True)
        finally:
            safe_rmpath(testfn)
    else:
        sproc = subprocess.Popen(cmd, **kwds)
        _subprocesses_started.add(sproc)
        wait_for_pid(sproc.pid)
    return sproc


@_reap_children_on_err
def spawn_children_pair():
    """Create a subprocess which creates another one as in:
    A (us) -> B (child) -> C (grandchild).
    Return a (child, grandchild) tuple.
    The 2 processes are fully initialized and will live for 60 secs
    and are registered for cleanup on reap_children().
    """
    tfile = None
    testfn = get_testfn(dir=os.getcwd())
    try:
        s = textwrap.dedent(f"""\
            import subprocess, os, sys, time
            s = "import os, time;"
            s += "f = open('{os.path.basename(testfn)}', 'w');"
            s += "f.write(str(os.getpid()));"
            s += "f.close();"
            s += "[time.sleep(0.1) for x in range(100 * 6)];"
            p = subprocess.Popen([r'{PYTHON_EXE}', '-c', s])
            p.wait()
            """)
        # On Windows if we create a subprocess with CREATE_NO_WINDOW flag
        # set (which is the default) a "conhost.exe" extra process will be
        # spawned as a child. We don't want that.
        if WINDOWS:
            subp, tfile = pyrun(s, creationflags=0)
        else:
            subp, tfile = pyrun(s)
        child = psutil.Process(subp.pid)
        grandchild_pid = int(wait_for_file(testfn, delete=True, empty=False))
        _pids_started.add(grandchild_pid)
        grandchild = psutil.Process(grandchild_pid)
        return (child, grandchild)
    finally:
        safe_rmpath(testfn)
        if tfile is not None:
            safe_rmpath(tfile)


def spawn_zombie():
    """Create a zombie process and return a (parent, zombie) process tuple.
    In order to kill the zombie parent must be terminate()d first, then
    zombie must be wait()ed on.
    """
    assert psutil.POSIX
    unix_file = get_testfn()
    src = textwrap.dedent(f"""\
        import os, sys, time, socket, contextlib
        child_pid = os.fork()
        if child_pid > 0:
            time.sleep(3000)
        else:
            # this is the zombie process
            with socket.socket(socket.AF_UNIX) as s:
                s.connect('{unix_file}')
                pid = bytes(str(os.getpid()), 'ascii')
                s.sendall(pid)
        """)
    tfile = None
    sock = bind_unix_socket(unix_file)
    try:
        sock.settimeout(GLOBAL_TIMEOUT)
        parent, tfile = pyrun(src)
        conn, _ = sock.accept()
        try:
            select.select([conn.fileno()], [], [], GLOBAL_TIMEOUT)
            zpid = int(conn.recv(1024))
            _pids_started.add(zpid)
            zombie = psutil.Process(zpid)
            call_until(lambda: zombie.status() == psutil.STATUS_ZOMBIE)
            return (parent, zombie)
        finally:
            conn.close()
    finally:
        sock.close()
        safe_rmpath(unix_file)
        if tfile is not None:
            safe_rmpath(tfile)


@_reap_children_on_err
def pyrun(src, **kwds):
    """Run python 'src' code string in a separate interpreter.
    Returns a subprocess.Popen instance and the test file where the source
    code was written.
    """
    kwds.setdefault("stdout", None)
    kwds.setdefault("stderr", None)
    srcfile = get_testfn()
    try:
        with open(srcfile, "w") as f:
            f.write(src)
        subp = spawn_subproc([PYTHON_EXE, f.name], **kwds)
        wait_for_pid(subp.pid)
        return (subp, srcfile)
    except Exception:
        safe_rmpath(srcfile)
        raise


@_reap_children_on_err
def sh(cmd, **kwds):
    """Run cmd in a subprocess and return its output.
    raises RuntimeError on error.
    """
    # Prevents subprocess to open error dialogs in case of error.
    flags = 0x8000000 if WINDOWS else 0
    kwds.setdefault("stdout", subprocess.PIPE)
    kwds.setdefault("stderr", subprocess.PIPE)
    kwds.setdefault("universal_newlines", True)
    kwds.setdefault("creationflags", flags)
    if isinstance(cmd, str):
        cmd = shlex.split(cmd)
    p = subprocess.Popen(cmd, **kwds)
    _subprocesses_started.add(p)
    stdout, stderr = p.communicate(timeout=GLOBAL_TIMEOUT)
    if p.returncode != 0:
        raise RuntimeError(stdout + stderr)
    if stderr:
        warn(stderr)
    if stdout.endswith('\n'):
        stdout = stdout[:-1]
    return stdout


def terminate(proc_or_pid, sig=signal.SIGTERM, wait_timeout=GLOBAL_TIMEOUT):
    """Terminate a process and wait() for it.
    Process can be a PID or an instance of psutil.Process(),
    subprocess.Popen() or psutil.Popen().
    If it's a subprocess.Popen() or psutil.Popen() instance also closes
    its stdin / stdout / stderr fds.
    PID is wait()ed even if the process is already gone (kills zombies).
    Does nothing if the process does not exist.
    Return process exit status.
    """

    def wait(proc, timeout):
        proc.wait(timeout)
        if WINDOWS and isinstance(proc, subprocess.Popen):
            # Otherwise PID may still hang around.
            try:
                return psutil.Process(proc.pid).wait(timeout)
            except psutil.NoSuchProcess:
                pass

    def sendsig(proc, sig):
        # XXX: otherwise the build hangs for some reason.
        if MACOS and GITHUB_ACTIONS:
            sig = signal.SIGKILL
        # If the process received SIGSTOP, SIGCONT is necessary first,
        # otherwise SIGTERM won't work.
        if POSIX and sig != signal.SIGKILL:
            proc.send_signal(signal.SIGCONT)
        proc.send_signal(sig)

    def term_subprocess_proc(proc, timeout):
        try:
            sendsig(proc, sig)
        except ProcessLookupError:
            pass
        except OSError as err:
            if WINDOWS and err.winerror == 6:  # "invalid handle"
                pass
            raise
        return wait(proc, timeout)

    def term_psutil_proc(proc, timeout):
        try:
            sendsig(proc, sig)
        except psutil.NoSuchProcess:
            pass
        return wait(proc, timeout)

    def term_pid(pid, timeout):
        try:
            proc = psutil.Process(pid)
        except psutil.NoSuchProcess:
            # Needed to kill zombies.
            if POSIX:
                return wait_pid(pid, timeout)
        else:
            return term_psutil_proc(proc, timeout)

    def flush_popen(proc):
        if proc.stdout:
            proc.stdout.close()
        if proc.stderr:
            proc.stderr.close()
        # Flushing a BufferedWriter may raise an error.
        if proc.stdin:
            proc.stdin.close()

    p = proc_or_pid
    try:
        if isinstance(p, int):
            return term_pid(p, wait_timeout)
        elif isinstance(p, (psutil.Process, psutil.Popen)):
            return term_psutil_proc(p, wait_timeout)
        elif isinstance(p, subprocess.Popen):
            return term_subprocess_proc(p, wait_timeout)
        else:
            raise TypeError(f"wrong type {p!r}")
    finally:
        if isinstance(p, (subprocess.Popen, psutil.Popen)):
            flush_popen(p)
        pid = p if isinstance(p, int) else p.pid
        assert not psutil.pid_exists(pid), pid


def reap_children(recursive=False):
    """Terminate and wait() any subprocess started by this test suite
    and any children currently running, ensuring that no processes stick
    around to hog resources.
    If recursive is True it also tries to terminate and wait()
    all grandchildren started by this process.
    """
    # Get the children here before terminating them, as in case of
    # recursive=True we don't want to lose the intermediate reference
    # pointing to the grandchildren.
    children = psutil.Process().children(recursive=recursive)

    # Terminate subprocess.Popen.
    while _subprocesses_started:
        subp = _subprocesses_started.pop()
        terminate(subp)

    # Collect started pids.
    while _pids_started:
        pid = _pids_started.pop()
        terminate(pid)

    # Terminate children.
    if children:
        for p in children:
            terminate(p, wait_timeout=None)
        _, alive = psutil.wait_procs(children, timeout=GLOBAL_TIMEOUT)
        for p in alive:
            warn(f"couldn't terminate process {p!r}; attempting kill()")
            terminate(p, sig=signal.SIGKILL)


# ===================================================================
# --- OS
# ===================================================================


def kernel_version():
    """Return a tuple such as (2, 6, 36)."""
    if not POSIX:
        raise NotImplementedError("not POSIX")
    s = ""
    uname = os.uname()[2]
    for c in uname:
        if c.isdigit() or c == '.':
            s += c
        else:
            break
    if not s:
        raise ValueError(f"can't parse {uname!r}")
    minor = 0
    micro = 0
    nums = s.split('.')
    major = int(nums[0])
    if len(nums) >= 2:
        minor = int(nums[1])
    if len(nums) >= 3:
        micro = int(nums[2])
    return (major, minor, micro)


def get_winver():
    if not WINDOWS:
        raise NotImplementedError("not WINDOWS")
    wv = sys.getwindowsversion()
    sp = wv.service_pack_major or 0
    return (wv[0], wv[1], sp)


# ===================================================================
# --- sync primitives
# ===================================================================


class retry:
    """A retry decorator."""

    def __init__(
        self,
        exception=Exception,
        timeout=None,
        retries=None,
        interval=0.001,
        logfun=None,
    ):
        if timeout and retries:
            raise ValueError("timeout and retries args are mutually exclusive")
        self.exception = exception
        self.timeout = timeout
        self.retries = retries
        self.interval = interval
        self.logfun = logfun

    def __iter__(self):
        if self.timeout:
            stop_at = time.time() + self.timeout
            while time.time() < stop_at:
                yield
        elif self.retries:
            for _ in range(self.retries):
                yield
        else:
            while True:
                yield

    def sleep(self):
        if self.interval is not None:
            time.sleep(self.interval)

    def __call__(self, fun):
        @functools.wraps(fun)
        def wrapper(*args, **kwargs):
            exc = None
            for _ in self:
                try:
                    return fun(*args, **kwargs)
                except self.exception as _:
                    exc = _
                    if self.logfun is not None:
                        self.logfun(exc)
                    self.sleep()
                    continue

            raise exc

        # This way the user of the decorated function can change config
        # parameters.
        wrapper.decorator = self
        return wrapper


@retry(
    exception=psutil.NoSuchProcess,
    logfun=None,
    timeout=GLOBAL_TIMEOUT,
    interval=0.001,
)
def wait_for_pid(pid):
    """Wait for pid to show up in the process list then return.
    Used in the test suite to give time the sub process to initialize.
    """
    if pid not in psutil.pids():
        raise psutil.NoSuchProcess(pid)
    psutil.Process(pid)


@retry(
    exception=(FileNotFoundError, AssertionError),
    logfun=None,
    timeout=GLOBAL_TIMEOUT,
    interval=0.001,
)
def wait_for_file(fname, delete=True, empty=False):
    """Wait for a file to be written on disk with some content."""
    with open(fname, "rb") as f:
        data = f.read()
    if not empty:
        assert data
    if delete:
        safe_rmpath(fname)
    return data


@retry(
    exception=(AssertionError, pytest.fail.Exception),
    logfun=None,
    timeout=GLOBAL_TIMEOUT,
    interval=0.001,
)
def call_until(fun):
    """Keep calling function until it evaluates to True."""
    ret = fun()
    assert ret
    return ret


# ===================================================================
# --- fs
# ===================================================================


def safe_rmpath(path):
    """Convenience function for removing temporary test files or dirs."""

    def retry_fun(fun):
        # On Windows it could happen that the file or directory has
        # open handles or references preventing the delete operation
        # to succeed immediately, so we retry for a while. See:
        # https://bugs.python.org/issue33240
        stop_at = time.time() + GLOBAL_TIMEOUT
        while time.time() < stop_at:
            try:
                return fun()
            except FileNotFoundError:
                pass
            except OSError as _:
                err = _
                warn(f"ignoring {err}")
            time.sleep(0.01)
        raise err

    try:
        st = os.stat(path)
        if stat.S_ISDIR(st.st_mode):
            fun = functools.partial(shutil.rmtree, path)
        else:
            fun = functools.partial(os.remove, path)
        if POSIX:
            fun()
        else:
            retry_fun(fun)
    except FileNotFoundError:
        pass


def safe_mkdir(dir):
    """Convenience function for creating a directory."""
    try:
        os.mkdir(dir)
    except FileExistsError:
        pass


@contextlib.contextmanager
def chdir(dirname):
    """Context manager which temporarily changes the current directory."""
    curdir = os.getcwd()
    try:
        os.chdir(dirname)
        yield
    finally:
        os.chdir(curdir)


def create_py_exe(path):
    """Create a Python executable file in the given location."""
    assert not os.path.exists(path), path
    atexit.register(safe_rmpath, path)
    shutil.copyfile(PYTHON_EXE, path)
    if POSIX:
        st = os.stat(path)
        os.chmod(path, st.st_mode | stat.S_IEXEC)
    return path


def create_c_exe(path, c_code=None):
    """Create a compiled C executable in the given location."""
    assert not os.path.exists(path), path
    if not shutil.which("gcc"):
        return pytest.skip("gcc is not installed")
    if c_code is None:
        c_code = textwrap.dedent("""
            #include <unistd.h>
            int main() {
                pause();
                return 1;
            }
            """)
    else:
        assert isinstance(c_code, str), c_code

    atexit.register(safe_rmpath, path)
    with open(get_testfn(suffix='.c'), "w") as f:
        f.write(c_code)
    try:
        subprocess.check_call(["gcc", f.name, "-o", path])
    finally:
        safe_rmpath(f.name)
    return path


def get_testfn(suffix="", dir=None):
    """Return an absolute pathname of a file or dir that did not
    exist at the time this call is made. Also schedule it for safe
    deletion at interpreter exit. It's technically racy but probably
    not really due to the time variant.
    """
    while True:
        name = tempfile.mktemp(prefix=TESTFN_PREFIX, suffix=suffix, dir=dir)
        if not os.path.exists(name):  # also include dirs
            path = os.path.realpath(name)  # needed for OSX
            atexit.register(safe_rmpath, path)
            return path


# ===================================================================
# --- testing
# ===================================================================


class PsutilTestCase(unittest.TestCase):
    """Test class providing auto-cleanup wrappers on top of process
    test utilities. All test classes should derive from this one, even
    if we use pytest.
    """

    # Print a full path representation of the single unit test being
    # run, similar to pytest output. Used only when running tests with
    # the unittest runner.
    def __str__(self):
        fqmod = self.__class__.__module__
        if not fqmod.startswith('psutil.'):
            fqmod = 'tests.' + fqmod
        return "{}.{}.{}".format(
            fqmod,
            self.__class__.__name__,
            self._testMethodName,
        )

    def get_testfn(self, suffix="", dir=None):
        fname = get_testfn(suffix=suffix, dir=dir)
        self.addCleanup(safe_rmpath, fname)
        return fname

    def spawn_subproc(self, *args, **kwds):
        sproc = spawn_subproc(*args, **kwds)
        self.addCleanup(terminate, sproc)
        return sproc

    def spawn_psproc(self, *args, **kwargs):
        sproc = self.spawn_subproc(*args, **kwargs)
        try:
            return psutil.Process(sproc.pid)
        except psutil.NoSuchProcess:
            self.assert_pid_gone(sproc.pid)
            raise

    def spawn_children_pair(self):
        child1, child2 = spawn_children_pair()
        self.addCleanup(terminate, child2)
        self.addCleanup(terminate, child1)  # executed first
        return (child1, child2)

    def spawn_zombie(self):
        parent, zombie = spawn_zombie()
        self.addCleanup(terminate, zombie)
        self.addCleanup(terminate, parent)  # executed first
        return (parent, zombie)

    def pyrun(self, *args, **kwds):
        sproc, srcfile = pyrun(*args, **kwds)
        self.addCleanup(safe_rmpath, srcfile)
        self.addCleanup(terminate, sproc)  # executed first
        return sproc

    def _check_proc_exc(self, proc, exc):
        assert isinstance(exc, psutil.Error)
        assert exc.pid == proc.pid
        assert exc.name == proc._name
        if exc.name:
            assert exc.name
        if isinstance(exc, psutil.ZombieProcess):
            assert exc.ppid == proc._ppid
            if exc.ppid is not None:
                assert exc.ppid >= 0
        str(exc)
        repr(exc)

    def assert_pid_gone(self, pid):
        try:
            proc = psutil.Process(pid)
        except psutil.ZombieProcess:
            raise AssertionError("wasn't supposed to raise ZombieProcess")
        except psutil.NoSuchProcess as exc:
            assert exc.pid == pid  # noqa: PT017
            assert exc.name is None  # noqa: PT017
        else:
            raise AssertionError(f"did not raise NoSuchProcess ({proc})")

        assert not psutil.pid_exists(pid), pid
        assert pid not in psutil.pids()
        assert pid not in [x.pid for x in psutil.process_iter()]

    def assert_proc_gone(self, proc):
        self.assert_pid_gone(proc.pid)
        ns = process_namespace(proc)
        for fun, name in ns.iter(ns.all, clear_cache=True):
            with self.subTest(proc=str(proc), name=name):
                try:
                    ret = fun()
                except psutil.ZombieProcess:
                    raise
                except psutil.NoSuchProcess as exc:
                    self._check_proc_exc(proc, exc)
                else:
                    msg = (
                        f"Process.{name}() didn't raise NSP and returned"
                        f" {ret!r}"
                    )
                    raise AssertionError(msg)
        proc.wait(timeout=0)  # assert not raise TimeoutExpired

    def assert_proc_zombie(self, proc):
        def assert_in_pids(proc):
            if MACOS:
                # Even ps does not show zombie PIDs for some reason. Weird...
                return
            assert proc.pid in psutil.pids()
            assert proc.pid in [x.pid for x in psutil.process_iter()]
            psutil._pmap = {}
            assert proc.pid in [x.pid for x in psutil.process_iter()]

        # A zombie process should always be instantiable.
        clone = psutil.Process(proc.pid)
        # Cloned zombie on Open/NetBSD/illumos/Solaris has null creation
        # time, see:
        # https://github.com/giampaolo/psutil/issues/2287
        # https://github.com/giampaolo/psutil/issues/2593
        assert proc == clone
        if not (OPENBSD or NETBSD or SUNOS):
            assert hash(proc) == hash(clone)
        # Its status always be querable.
        assert proc.status() == psutil.STATUS_ZOMBIE
        # It should be considered 'running'.
        assert proc.is_running()
        assert psutil.pid_exists(proc.pid)
        # as_dict() shouldn't crash.
        proc.as_dict()
        # It should show up in pids() and process_iter().
        assert_in_pids(proc)
        # Call all methods.
        ns = process_namespace(proc)
        for fun, name in ns.iter(ns.all, clear_cache=True):
            with self.subTest(proc=str(proc), name=name):
                try:
                    fun()
                except (psutil.ZombieProcess, psutil.AccessDenied) as exc:
                    self._check_proc_exc(proc, exc)
        if LINUX:
            # https://github.com/giampaolo/psutil/pull/2288
            with pytest.raises(psutil.ZombieProcess) as cm:
                proc.cmdline()
            self._check_proc_exc(proc, cm.value)
            with pytest.raises(psutil.ZombieProcess) as cm:
                proc.exe()
            self._check_proc_exc(proc, cm.value)
            with pytest.raises(psutil.ZombieProcess) as cm:
                proc.memory_maps()
            self._check_proc_exc(proc, cm.value)
        # Zombie cannot be signaled or terminated.
        proc.suspend()
        proc.resume()
        proc.terminate()
        proc.kill()
        assert proc.is_running()
        assert psutil.pid_exists(proc.pid)
        assert_in_pids(proc)

        # Its parent should 'see' it (edit: not true on BSD and MACOS).
        # descendants = [x.pid for x in psutil.Process().children(
        #                recursive=True)]
        # assert proc.pid in descendants

        # __eq__ can't be relied upon because creation time may not be
        # querable.
        # assert proc ==  psutil.Process(proc.pid)

        # XXX should we also assume ppid() to be usable? Note: this
        # would be an important use case as the only way to get
        # rid of a zombie is to kill its parent.
        # assert proc == ppid(), os.getpid()


def is_win_secure_system_proc(pid):
    # see: https://github.com/giampaolo/psutil/issues/2338
    @memoize
    def get_procs():
        ret = {}
        out = sh("tasklist.exe /NH /FO csv")
        for line in out.splitlines()[1:]:
            bits = [x.replace('"', "") for x in line.split(",")]
            name, pid = bits[0], int(bits[1])
            ret[pid] = name
        return ret

    try:
        return get_procs()[pid] == "Secure System"
    except KeyError:
        return False


def _get_eligible_cpu():
    p = psutil.Process()
    if hasattr(p, "cpu_num"):
        return p.cpu_num()
    elif hasattr(p, "cpu_affinity"):
        return random.choice(p.cpu_affinity())
    return 0


class process_namespace:
    """A container that lists all Process class method names + some
    reasonable parameters to be called with. Utility methods (parent(),
    children(), ...) are excluded.

    >>> ns = process_namespace(psutil.Process())
    >>> for fun, name in ns.iter(ns.getters):
    ...    fun()
    """

    utils = [('cpu_percent', (), {}), ('memory_percent', (), {})]

    ignored = [
        ('as_dict', (), {}),
        ('children', (), {'recursive': True}),
        ('connections', (), {}),  # deprecated
        ('is_running', (), {}),
        ('oneshot', (), {}),
        ('parent', (), {}),
        ('parents', (), {}),
        ('pid', (), {}),
        ('wait', (0,), {}),
    ]

    getters = [
        ('cmdline', (), {}),
        ('cpu_times', (), {}),
        ('create_time', (), {}),
        ('cwd', (), {}),
        ('exe', (), {}),
        ('memory_full_info', (), {}),
        ('memory_info', (), {}),
        ('name', (), {}),
        ('net_connections', (), {'kind': 'all'}),
        ('nice', (), {}),
        ('num_ctx_switches', (), {}),
        ('num_threads', (), {}),
        ('open_files', (), {}),
        ('ppid', (), {}),
        ('status', (), {}),
        ('threads', (), {}),
        ('username', (), {}),
    ]
    if POSIX:
        getters += [('uids', (), {})]
        getters += [('gids', (), {})]
        getters += [('terminal', (), {})]
        getters += [('num_fds', (), {})]
    if HAS_PROC_IO_COUNTERS:
        getters += [('io_counters', (), {})]
    if HAS_IONICE:
        getters += [('ionice', (), {})]
    if HAS_RLIMIT:
        getters += [('rlimit', (psutil.RLIMIT_NOFILE,), {})]
    if HAS_CPU_AFFINITY:
        getters += [('cpu_affinity', (), {})]
    if HAS_PROC_CPU_NUM:
        getters += [('cpu_num', (), {})]
    if HAS_ENVIRON:
        getters += [('environ', (), {})]
    if WINDOWS:
        getters += [('num_handles', (), {})]
    if HAS_MEMORY_MAPS:
        getters += [('memory_maps', (), {'grouped': False})]

    setters = []
    if POSIX:
        setters += [('nice', (0,), {})]
    else:
        setters += [('nice', (psutil.NORMAL_PRIORITY_CLASS,), {})]
    if HAS_RLIMIT:
        setters += [('rlimit', (psutil.RLIMIT_NOFILE, (1024, 4096)), {})]
    if HAS_IONICE:
        if LINUX:
            setters += [('ionice', (psutil.IOPRIO_CLASS_NONE, 0), {})]
        else:
            setters += [('ionice', (psutil.IOPRIO_NORMAL,), {})]
    if HAS_CPU_AFFINITY:
        setters += [('cpu_affinity', ([_get_eligible_cpu()],), {})]

    killers = [
        ('send_signal', (signal.SIGTERM,), {}),
        ('suspend', (), {}),
        ('resume', (), {}),
        ('terminate', (), {}),
        ('kill', (), {}),
    ]
    if WINDOWS:
        killers += [('send_signal', (signal.CTRL_C_EVENT,), {})]
        killers += [('send_signal', (signal.CTRL_BREAK_EVENT,), {})]

    all = utils + getters + setters + killers

    def __init__(self, proc):
        self._proc = proc

    def iter(self, ls, clear_cache=True):
        """Given a list of tuples yields a set of (fun, fun_name) tuples
        in random order.
        """
        ls = list(ls)
        random.shuffle(ls)
        for fun_name, args, kwds in ls:
            if clear_cache:
                self.clear_cache()
            fun = getattr(self._proc, fun_name)
            fun = functools.partial(fun, *args, **kwds)
            yield (fun, fun_name)

    def clear_cache(self):
        """Clear the cache of a Process instance."""
        self._proc._init(self._proc.pid, _ignore_nsp=True)

    @classmethod
    def test_class_coverage(cls, test_class, ls):
        """Given a TestCase instance and a list of tuples checks that
        the class defines the required test method names.
        """
        for fun_name, _, _ in ls:
            meth_name = 'test_' + fun_name
            if not hasattr(test_class, meth_name):
                msg = (
                    f"{test_class.__class__.__name__!r} class should define a"
                    f" {meth_name!r} method"
                )
                raise AttributeError(msg)

    @classmethod
    def test(cls):
        this = {x[0] for x in cls.all}
        ignored = {x[0] for x in cls.ignored}
        klass = {x for x in dir(psutil.Process) if x[0] != '_'}
        leftout = (this | ignored) ^ klass
        if leftout:
            raise ValueError(f"uncovered Process class names: {leftout!r}")


class system_namespace:
    """A container that lists all the module-level, system-related APIs.
    Utilities such as cpu_percent() are excluded. Usage:

    >>> ns = system_namespace
    >>> for fun, name in ns.iter(ns.getters):
    ...    fun()
    """

    getters = [
        ('boot_time', (), {}),
        ('cpu_count', (), {'logical': False}),
        ('cpu_count', (), {'logical': True}),
        ('cpu_stats', (), {}),
        ('cpu_times', (), {'percpu': False}),
        ('cpu_times', (), {'percpu': True}),
        ('disk_io_counters', (), {'perdisk': True}),
        ('disk_partitions', (), {'all': True}),
        ('disk_usage', (os.getcwd(),), {}),
        ('net_connections', (), {'kind': 'all'}),
        ('net_if_addrs', (), {}),
        ('net_if_stats', (), {}),
        ('net_io_counters', (), {'pernic': True}),
        ('pid_exists', (os.getpid(),), {}),
        ('pids', (), {}),
        ('swap_memory', (), {}),
        ('users', (), {}),
        ('virtual_memory', (), {}),
    ]

    if HAS_CPU_FREQ:
        if MACOS and AARCH64:  # skipped due to #1892
            pass
        else:
            getters += [('cpu_freq', (), {'percpu': True})]
    if HAS_GETLOADAVG:
        getters += [('getloadavg', (), {})]
    if HAS_SENSORS_TEMPERATURES:
        getters += [('sensors_temperatures', (), {})]
    if HAS_SENSORS_FANS:
        getters += [('sensors_fans', (), {})]
    if HAS_SENSORS_BATTERY:
        getters += [('sensors_battery', (), {})]
    if HAS_HEAP_INFO:
        getters += [('heap_info', (), {})]
        getters += [('heap_trim', (), {})]

    if WINDOWS:
        getters += [('win_service_iter', (), {})]
        getters += [('win_service_get', ('alg',), {})]

    ignored = [
        ('process_iter', (), {}),
        ('wait_procs', ([psutil.Process()],), {}),
        ('cpu_percent', (), {}),
        ('cpu_times_percent', (), {}),
    ]

    all = getters

    @staticmethod
    def iter(ls):
        """Given a list of tuples yields a set of (fun, fun_name) tuples
        in random order.
        """
        ls = list(ls)
        random.shuffle(ls)
        for fun_name, args, kwds in ls:
            fun = getattr(psutil, fun_name)
            fun = functools.partial(fun, *args, **kwds)
            yield (fun, fun_name)

    test_class_coverage = process_namespace.test_class_coverage


def retry_on_failure(retries=NO_RETRIES):
    """Decorator which runs a test function and retries N times before
    giving up and failing.
    """

    def decorator(test_method):
        @functools.wraps(test_method)
        def wrapper(self, *args, **kwargs):
            err = None
            for attempt in range(retries):
                try:
                    return test_method(self, *args, **kwargs)
                except (AssertionError, pytest.fail.Exception) as _:
                    err = _
                    prefix = "\n" if attempt == 0 else ""
                    short_err = str(err).split("\n")[0]
                    print(  # noqa: T201
                        f"{prefix}{short_err}, retrying"
                        f" {attempt + 1}/{retries} ...",
                        file=sys.stderr,
                    )
                    if hasattr(self, "tearDown"):
                        self.tearDown()
                    if hasattr(self, "teardown_method"):
                        self.teardown_method()
                    if hasattr(self, "setUp"):
                        self.setUp()
                    if hasattr(self, "setup_method"):
                        self.setup_method()

            raise err

        return wrapper

    assert retries > 1, retries
    return decorator


def skip_on_access_denied(only_if=None):
    """Decorator to Ignore AccessDenied exceptions."""

    def decorator(fun):
        @functools.wraps(fun)
        def wrapper(*args, **kwargs):
            try:
                return fun(*args, **kwargs)
            except psutil.AccessDenied:
                if only_if is not None:
                    if not only_if:
                        raise
                return pytest.skip("raises AccessDenied")

        return wrapper

    return decorator


def skip_on_not_implemented(only_if=None):
    """Decorator to Ignore NotImplementedError exceptions."""

    def decorator(fun):
        @functools.wraps(fun)
        def wrapper(*args, **kwargs):
            try:
                return fun(*args, **kwargs)
            except NotImplementedError:
                if only_if is not None:
                    if not only_if:
                        raise
                msg = (
                    f"{fun.__name__!r} was skipped because it raised"
                    " NotImplementedError"
                )
                return pytest.skip(msg)

        return wrapper

    return decorator


# ===================================================================
# --- network
# ===================================================================


# XXX: no longer used
def get_free_port(host='127.0.0.1'):
    """Return an unused TCP port. Subject to race conditions."""
    with socket.socket() as sock:
        sock.bind((host, 0))
        return sock.getsockname()[1]


def bind_socket(family=AF_INET, type=SOCK_STREAM, addr=None):
    """Binds a generic socket."""
    if addr is None and family in {AF_INET, AF_INET6}:
        addr = ("", 0)
    sock = socket.socket(family, type)
    try:
        if os.name not in {'nt', 'cygwin'}:
            sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        sock.bind(addr)
        if type == socket.SOCK_STREAM:
            sock.listen(5)
        return sock
    except Exception:
        sock.close()
        raise


def bind_unix_socket(name, type=socket.SOCK_STREAM):
    """Bind a UNIX socket."""
    assert psutil.POSIX
    assert not os.path.exists(name), name
    sock = socket.socket(socket.AF_UNIX, type)
    try:
        sock.bind(name)
        if type == socket.SOCK_STREAM:
            sock.listen(5)
    except Exception:
        sock.close()
        raise
    return sock


def tcp_socketpair(family, addr=("", 0)):
    """Build a pair of TCP sockets connected to each other.
    Return a (server, client) tuple.
    """
    with socket.socket(family, SOCK_STREAM) as ll:
        ll.bind(addr)
        ll.listen(5)
        addr = ll.getsockname()
        c = socket.socket(family, SOCK_STREAM)
        try:
            c.connect(addr)
            caddr = c.getsockname()
            while True:
                a, addr = ll.accept()
                # check that we've got the correct client
                if addr == caddr:
                    return (a, c)
                a.close()
        except OSError:
            c.close()
            raise


def unix_socketpair(name):
    """Build a pair of UNIX sockets connected to each other through
    the same UNIX file name.
    Return a (server, client) tuple.
    """
    assert psutil.POSIX
    server = client = None
    try:
        server = bind_unix_socket(name, type=socket.SOCK_STREAM)
        server.setblocking(0)
        client = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
        client.setblocking(0)
        client.connect(name)
        # new = server.accept()
    except Exception:
        if server is not None:
            server.close()
        if client is not None:
            client.close()
        raise
    return (server, client)


@contextlib.contextmanager
def create_sockets():
    """Open as many socket families / types as possible."""
    socks = []
    fname1 = fname2 = None
    try:
        socks.extend((
            bind_socket(socket.AF_INET, socket.SOCK_STREAM),
            bind_socket(socket.AF_INET, socket.SOCK_DGRAM),
        ))
        if supports_ipv6():
            socks.extend((
                bind_socket(socket.AF_INET6, socket.SOCK_STREAM),
                bind_socket(socket.AF_INET6, socket.SOCK_DGRAM),
            ))
        if POSIX and HAS_NET_CONNECTIONS_UNIX:
            fname1 = get_testfn()
            fname2 = get_testfn()
            s1, s2 = unix_socketpair(fname1)
            s3 = bind_unix_socket(fname2, type=socket.SOCK_DGRAM)
            for s in (s1, s2, s3):
                socks.append(s)
        yield socks
    finally:
        for s in socks:
            s.close()
        for fname in (fname1, fname2):
            if fname is not None:
                safe_rmpath(fname)


def check_net_address(addr, family):
    """Check a net address validity. Supported families are IPv4,
    IPv6 and MAC addresses.
    """
    assert isinstance(family, enum.IntEnum), family
    if family == socket.AF_INET:
        octs = [int(x) for x in addr.split('.')]
        assert len(octs) == 4, addr
        for num in octs:
            assert 0 <= num <= 255, addr
        ipaddress.IPv4Address(addr)
    elif family == socket.AF_INET6:
        assert isinstance(addr, str), addr
        ipaddress.IPv6Address(addr)
    elif family == psutil.AF_LINK:
        assert re.match(r'([a-fA-F0-9]{2}[:|\-]?){6}', addr) is not None, addr
    else:
        raise ValueError(f"unknown family {family!r}")


def check_connection_ntuple(conn):
    """Check validity of a connection namedtuple."""

    def check_ntuple(conn):
        has_pid = len(conn) == 7
        assert len(conn) in {6, 7}, len(conn)
        assert conn[0] == conn.fd, conn.fd
        assert conn[1] == conn.family, conn.family
        assert conn[2] == conn.type, conn.type
        assert conn[3] == conn.laddr, conn.laddr
        assert conn[4] == conn.raddr, conn.raddr
        assert conn[5] == conn.status, conn.status
        if has_pid:
            assert conn[6] == conn.pid, conn.pid

    def check_family(conn):
        assert conn.family in {AF_INET, AF_INET6, AF_UNIX}, conn.family
        assert isinstance(conn.family, enum.IntEnum), conn
        if conn.family == AF_INET:
            # actually try to bind the local socket; ignore IPv6
            # sockets as their address might be represented as
            # an IPv4-mapped-address (e.g. "::127.0.0.1")
            # and that's rejected by bind()
            with socket.socket(conn.family, conn.type) as s:
                try:
                    s.bind((conn.laddr[0], 0))
                except OSError as err:
                    if err.errno != errno.EADDRNOTAVAIL:
                        raise
        elif conn.family == AF_UNIX:
            assert conn.status == psutil.CONN_NONE, conn.status

    def check_type(conn):
        # SOCK_SEQPACKET may happen in case of AF_UNIX socks
        SOCK_SEQPACKET = getattr(socket, "SOCK_SEQPACKET", object())
        assert conn.type in {
            socket.SOCK_STREAM,
            socket.SOCK_DGRAM,
            SOCK_SEQPACKET,
        }, conn.type
        assert isinstance(conn.type, enum.IntEnum), conn
        if conn.type == socket.SOCK_DGRAM:
            assert conn.status == psutil.CONN_NONE, conn.status

    def check_addrs(conn):
        # check IP address and port sanity
        for addr in (conn.laddr, conn.raddr):
            if conn.family in {AF_INET, AF_INET6}:
                assert isinstance(addr, tuple), type(addr)
                if not addr:
                    continue
                assert isinstance(addr.port, int), type(addr.port)
                assert 0 <= addr.port <= 65535, addr.port
                check_net_address(addr.ip, conn.family)
            elif conn.family == AF_UNIX:
                assert isinstance(addr, str), type(addr)

    def check_status(conn):
        assert isinstance(conn.status, str), conn.status
        valids = [
            getattr(psutil, x) for x in dir(psutil) if x.startswith('CONN_')
        ]
        assert conn.status in valids, conn.status
        if conn.family in {AF_INET, AF_INET6} and conn.type == SOCK_STREAM:
            assert conn.status != psutil.CONN_NONE, conn.status
        else:
            assert conn.status == psutil.CONN_NONE, conn.status

    check_ntuple(conn)
    check_family(conn)
    check_type(conn)
    check_addrs(conn)
    check_status(conn)


def filter_proc_net_connections(cons):
    """Our process may start with some open UNIX sockets which are not
    initialized by us, invalidating unit tests.
    """
    new = []
    for conn in cons:
        if POSIX and conn.family == socket.AF_UNIX:
            if MACOS and "/syslog" in conn.raddr:
                debug(f"skipping {conn}")
                continue
        new.append(conn)
    return new


# ===================================================================
# --- import utils
# ===================================================================


def reload_module(module):
    return importlib.reload(module)


def import_module_by_path(path):
    name = os.path.splitext(os.path.basename(path))[0]
    spec = importlib.util.spec_from_file_location(name, path)
    mod = importlib.util.module_from_spec(spec)
    spec.loader.exec_module(mod)
    return mod


# ===================================================================
# --- others
# ===================================================================


def warn(msg):
    """Raise a warning msg."""
    warnings.warn(msg, UserWarning, stacklevel=2)


def is_namedtuple(x):
    """Check if object is an instance of namedtuple."""
    t = type(x)
    b = t.__bases__
    if len(b) != 1 or b[0] is not tuple:
        return False
    f = getattr(t, '_fields', None)
    if not isinstance(f, tuple):
        return False
    return all(isinstance(n, str) for n in f)


if POSIX:

    @contextlib.contextmanager
    def copyload_shared_lib(suffix=""):
        """Ctx manager which picks up a random shared CO lib used
        by this process, copies it in another location and loads it
        in memory via ctypes. Return the new absolutized path.
        """
        exe = 'pypy' if PYPY else 'python'
        ext = ".so"
        dst = get_testfn(suffix=suffix + ext)
        libs = [
            x.path
            for x in psutil.Process().memory_maps()
            if os.path.splitext(x.path)[1] == ext and exe in x.path.lower()
        ]
        src = random.choice(libs)
        shutil.copyfile(src, dst)
        try:
            ctypes.CDLL(dst)
            yield dst
        finally:
            safe_rmpath(dst)

else:

    @contextlib.contextmanager
    def copyload_shared_lib(suffix=""):
        """Ctx manager which picks up a random shared DLL lib used
        by this process, copies it in another location and loads it
        in memory via ctypes.
        Return the new absolutized, normcased path.
        """
        from ctypes import WinError
        from ctypes import wintypes

        ext = ".dll"
        dst = get_testfn(suffix=suffix + ext)
        libs = [
            x.path
            for x in psutil.Process().memory_maps()
            if x.path.lower().endswith(ext)
            and 'python' in os.path.basename(x.path).lower()
            and 'wow64' not in x.path.lower()
        ]
        if PYPY and not libs:
            libs = [
                x.path
                for x in psutil.Process().memory_maps()
                if 'pypy' in os.path.basename(x.path).lower()
            ]
        src = random.choice(libs)
        shutil.copyfile(src, dst)
        cfile = None
        try:
            cfile = ctypes.WinDLL(dst)
            yield dst
        finally:
            # Work around OverflowError:
            # - https://ci.appveyor.com/project/giampaolo/psutil/build/1207/
            #       job/o53330pbnri9bcw7
            # - http://bugs.python.org/issue30286
            # - http://stackoverflow.com/questions/23522055
            if cfile is not None:
                FreeLibrary = ctypes.windll.kernel32.FreeLibrary
                FreeLibrary.argtypes = [wintypes.HMODULE]
                ret = FreeLibrary(cfile._handle)
                if ret == 0:
                    raise WinError()
            safe_rmpath(dst)


# ===================================================================
# --- Exit funs (first is executed last)
# ===================================================================


# this is executed first
@atexit.register
def cleanup_test_procs():
    reap_children(recursive=True)


# atexit module does not execute exit functions in case of SIGTERM, which
# gets sent to test subprocesses, which is a problem if they import this
# module. With this it will. See:
# https://gmpy.dev/blog/2016/how-to-always-execute-exit-functions-in-python
if POSIX:
    signal.signal(signal.SIGTERM, lambda sig, _: sys.exit(sig))
