undetected-chromedriver/undetected_chromedriver/__init__.py

#!/usr/bin/env python3

"""

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         888                                                  888         Y8P
         888                                                  888
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d88P"    888 "88b 888P"  d88""88b 888 "888 "88b d8P  Y8b d88" 888 888P"   888 888  888 d8P  Y8b 888P"
888      888  888 888    888  888 888  888  888 88888888 888  888 888     888 Y88  88P 88888888 888
Y88b.    888  888 888    Y88..88P 888  888  888 Y8b.     Y88b 888 888     888  Y8bd8P  Y8b.     888
 "Y8888P 888  888 888     "Y88P"  888  888  888  "Y8888   "Y88888 888     888   Y88P    "Y8888  888   88888888

by UltrafunkAmsterdam (https://github.com/ultrafunkamsterdam)

"""
from __future__ import annotations


__version__ = "3.4.7"

import json
import logging
import os
import re
import shutil
import subprocess
import sys
import tempfile
import time
from weakref import finalize

import selenium.webdriver.chrome.service
import selenium.webdriver.chrome.webdriver
from selenium.webdriver.common.by import By
import selenium.webdriver.common.service
import selenium.webdriver.remote.command
import selenium.webdriver.remote.webdriver

from .cdp import CDP
from .dprocess import start_detached
from .options import ChromeOptions
from .patcher import IS_POSIX
from .patcher import Patcher
from .reactor import Reactor
from .webelement import UCWebElement
from .webelement import WebElement


__all__ = (
    "Chrome",
    "ChromeOptions",
    "Patcher",
    "Reactor",
    "CDP",
    "find_chrome_executable",
)

logger = logging.getLogger("uc")
logger.setLevel(logging.getLogger().getEffectiveLevel())


class Chrome(selenium.webdriver.chrome.webdriver.WebDriver):
    """

    Controls the ChromeDriver and allows you to drive the browser.

    The webdriver file will be downloaded by this module automatically,
    you do not need to specify this. however, you may if you wish.

    Attributes
    ----------

    Methods
    -------

    reconnect()

        this can be useful in case of heavy detection methods
        -stops the chromedriver service which runs in the background
        -starts the chromedriver service which runs in the background
        -recreate session


    start_session(capabilities=None, browser_profile=None)

        differentiates from the regular method in that it does not
        require a capabilities argument. The capabilities are automatically
        recreated from the options at creation time.

    --------------------------------------------------------------------------
        NOTE:
            Chrome has everything included to work out of the box.
            it does not `need` customizations.
            any customizations MAY lead to trigger bot migitation systems.

    --------------------------------------------------------------------------
    """

    _instances = set()
    session_id = None
    debug = False

    def __init__(
        self,
        options=None,
        user_data_dir=None,
        driver_executable_path=None,
        browser_executable_path=None,
        port=0,
        enable_cdp_events=False,
        service_args=None,
        service_creationflags=None,
        desired_capabilities=None,
        advanced_elements=False,
        service_log_path=None,
        keep_alive=True,
        log_level=0,
        headless=False,
        version_main=None,
        patcher_force_close=False,
        suppress_welcome=True,
        use_subprocess=True,
        debug=False,
        no_sandbox=True,
        user_multi_procs: bool = False,
        **kw,
    ):
        """
        Creates a new instance of the chrome driver.

        Starts the service and then creates new instance of chrome driver.

        Parameters
        ----------

        options: ChromeOptions, optional, default: None - automatic useful defaults
            this takes an instance of ChromeOptions, mainly to customize browser behavior.
            anything other dan the default, for example extensions or startup options
            are not supported in case of failure, and can probably lowers your undetectability.


        user_data_dir: str , optional, default: None (creates temp profile)
            if user_data_dir is a path to a valid chrome profile directory, use it,
            and turn off automatic removal mechanism at exit.

        driver_executable_path: str, optional, default: None(=downloads and patches new binary)

        browser_executable_path: str, optional, default: None - use find_chrome_executable
            Path to the browser executable.
            If not specified, make sure the executable's folder is in $PATH

        port: int, optional, default: 0
            port to be used by the chromedriver executable, this is NOT the debugger port.
            leave it at 0 unless you know what you are doing.
            the default value of 0 automatically picks an available port.

        enable_cdp_events: bool, default: False
            :: currently for chrome only
            this enables the handling of wire messages
            when enabled, you can subscribe to CDP events by using:

                driver.add_cdp_listener("Network.dataReceived", yourcallback)
                # yourcallback is an callable which accepts exactly 1 dict as parameter


        service_args: list of str, optional, default: None
            arguments to pass to the driver service

        desired_capabilities: dict, optional, default: None - auto from config
            Dictionary object with non-browser specific capabilities only, such as "item" or "loggingPref".

        advanced_elements:  bool, optional, default: False
            makes it easier to recognize elements like you know them from html/browser inspection, especially when working
            in an interactive environment

            default webelement repr:
            <selenium.webdriver.remote.webelement.WebElement (session="85ff0f671512fa535630e71ee951b1f2", element="6357cb55-92c3-4c0f-9416-b174f9c1b8c4")>

            advanced webelement repr
            <WebElement(<a class="mobile-show-inline-block mc-update-infos init-ok" href="#" id="main-cat-switcher-mobile">)>

            note: when retrieving large amounts of elements ( example: find_elements_by_tag("*") ) and print them, it does take a little more time.


        service_log_path: str, optional, default: None
             path to log information from the driver.

        keep_alive: bool, optional, default: True
             Whether to configure ChromeRemoteConnection to use HTTP keep-alive.

        log_level: int, optional, default: adapts to python global log level

        headless: bool, optional, default: False
            can also be specified in the options instance.
            Specify whether you want to use the browser in headless mode.
            warning: this lowers undetectability and not fully supported.

        version_main: int, optional, default: None (=auto)
            if you, for god knows whatever reason, use
            an older version of Chrome. You can specify it's full rounded version number
            here. Example: 87 for all versions of 87

        patcher_force_close: bool, optional, default: False
            instructs the patcher to do whatever it can to access the chromedriver binary
            if the file is locked, it will force shutdown all instances.
            setting it is not recommended, unless you know the implications and think
            you might need it.

        suppress_welcome: bool, optional , default: True
            a "welcome" alert might show up on *nix-like systems asking whether you want to set
            chrome as your default browser, and if you want to send even more data to google.
            now, in case you are nag-fetishist, or a diagnostics data feeder to google, you can set this to False.
            Note: if you don't handle the nag screen in time, the browser loses it's connection and throws an Exception.

        use_subprocess: bool, optional , default: True,

            False (the default) makes sure Chrome will get it's own process (so no subprocess of chromedriver.exe or python
                This fixes a LOT of issues, like multithreaded run, but mst importantly. shutting corectly after
                program exits or using .quit()
                you should be knowing what you're doing, and know how python works.

              unfortunately, there  is always an edge case in which one would like to write an single script with the only contents being:
              --start script--
              import undetected_chromedriver as uc
              d = uc.Chrome()
              d.get('https://somesite/')
              ---end script --

              and will be greeted with an error, since the program exists before chrome has a change to launch.
              in that case you can set this to `True`. The browser will start via subprocess, and will keep running most of times.
              ! setting it to True comes with NO support when being detected. !

        no_sandbox: bool, optional, default=True
             uses the --no-sandbox option, and additionally does suppress the "unsecure option" status bar
             this option has a default of True since many people seem to run this as root (....) , and chrome does not start
             when running as root without using --no-sandbox flag.

        user_multi_procs:
            set to true when you are using multithreads/multiprocessing
            ensures not all processes are trying to modify a binary which is in use by another.
            for this to work. YOU MUST HAVE AT LEAST 1 UNDETECTED_CHROMEDRIVER BINARY IN YOUR ROAMING DATA FOLDER.
            this requirement can be easily satisfied, by just running this program "normal" and close/kill it.


        """

        finalize(self, self._ensure_close, self)
        self.debug = debug
        self.patcher = Patcher(
            executable_path=driver_executable_path,
            force=patcher_force_close,
            version_main=version_main,
            user_multi_procs=user_multi_procs,
        )
        # self.patcher.auto(user_multiprocess = user_multi_num_procs)
        self.patcher.auto()

        # self.patcher = patcher
        if not options:
            options = ChromeOptions()

        try:
            if hasattr(options, "_session") and options._session is not None:
                #  prevent reuse of options,
                #  as it just appends arguments, not replace them
                #  you'll get conflicts starting chrome
                raise RuntimeError("you cannot reuse the ChromeOptions object")
        except AttributeError:
            pass

        options._session = self

        if not options.debugger_address:
            debug_port = (
                port
                if port != 0
                else selenium.webdriver.common.service.utils.free_port()
            )
            debug_host = "127.0.0.1"
            options.debugger_address = "%s:%d" % (debug_host, debug_port)
        else:
            debug_host, debug_port = options.debugger_address.split(":")
            debug_port = int(debug_port)

        if enable_cdp_events:
            options.set_capability(
                "goog:loggingPrefs", {"performance": "ALL", "browser": "ALL"}
            )

        options.add_argument("--remote-debugging-host=%s" % debug_host)
        options.add_argument("--remote-debugging-port=%s" % debug_port)

        if user_data_dir:
            options.add_argument("--user-data-dir=%s" % user_data_dir)

        language, keep_user_data_dir = None, bool(user_data_dir)

        # see if a custom user profile is specified in options
        for arg in options.arguments:

            if any([_ in arg for _ in ("--headless", "headless")]):
                options.arguments.remove(arg)
                options.headless = True

            if "lang" in arg:
                m = re.search("(?:--)?lang(?:[ =])?(.*)", arg)
                try:
                    language = m[1]
                except IndexError:
                    logger.debug("will set the language to en-US,en;q=0.9")
                    language = "en-US,en;q=0.9"

            if "user-data-dir" in arg:
                m = re.search("(?:--)?user-data-dir(?:[ =])?(.*)", arg)
                try:
                    user_data_dir = m[1]
                    logger.debug(
                        "user-data-dir found in user argument %s => %s" % (arg, m[1])
                    )
                    keep_user_data_dir = True

                except IndexError:
                    logger.debug(
                        "no user data dir could be extracted from supplied argument %s "
                        % arg
                    )

        if not user_data_dir:
            # backward compatiblity
            # check if an old uc.ChromeOptions is used, and extract the user data dir

            if hasattr(options, "user_data_dir") and getattr(
                options, "user_data_dir", None
            ):
                import warnings

                warnings.warn(
                    "using ChromeOptions.user_data_dir might stop working in future versions."
                    "use uc.Chrome(user_data_dir='/xyz/some/data') in case you need existing profile folder"
                )
                options.add_argument("--user-data-dir=%s" % options.user_data_dir)
                keep_user_data_dir = True
                logger.debug(
                    "user_data_dir property found in options object: %s" % user_data_dir
                )

            else:
                user_data_dir = os.path.normpath(tempfile.mkdtemp())
                keep_user_data_dir = False
                arg = "--user-data-dir=%s" % user_data_dir
                options.add_argument(arg)
                logger.debug(
                    "created a temporary folder in which the user-data (profile) will be stored during this\n"
                    "session, and added it to chrome startup arguments: %s" % arg
                )

        if not language:
            try:
                import locale

                language = locale.getdefaultlocale()[0].replace("_", "-")
            except Exception:
                pass
            if not language:
                language = "en-US"

        options.add_argument("--lang=%s" % language)

        if not options.binary_location:
            options.binary_location = (
                browser_executable_path or find_chrome_executable()
            )

        self._delay = 3

        self.user_data_dir = user_data_dir
        self.keep_user_data_dir = keep_user_data_dir

        if suppress_welcome:
            options.arguments.extend(["--no-default-browser-check", "--no-first-run"])
        if no_sandbox:
            options.arguments.extend(["--no-sandbox", "--test-type"])

        if headless or options.headless:
            #workaround until a better checking is found
            options.add_argument("--headless=new")
            #if self.patcher.version_main < 108:
            #    options.add_argument("--headless=chrome")
            #elif self.patcher.version_main >= 108:
            

        options.add_argument("--window-size=1920,1080")
        options.add_argument("--start-maximized")
        options.add_argument("--no-sandbox")
        # fixes "could not connect to chrome" error when running
        # on linux using privileged user like root (which i don't recommend)

        options.add_argument(
            "--log-level=%d" % log_level
            or divmod(logging.getLogger().getEffectiveLevel(), 10)[0]
        )

        if hasattr(options, "handle_prefs"):
            options.handle_prefs(user_data_dir)

        # fix exit_type flag to prevent tab-restore nag
        try:
            with open(
                os.path.join(user_data_dir, "Default/Preferences"),
                encoding="latin1",
                mode="r+",
            ) as fs:
                config = json.load(fs)
                if config["profile"]["exit_type"] is not None:
                    # fixing the restore-tabs-nag
                    config["profile"]["exit_type"] = None
                fs.seek(0, 0)
                json.dump(config, fs)
                fs.truncate()  # the file might be shorter
                logger.debug("fixed exit_type flag")
        except Exception as e:
            logger.debug("did not find a bad exit_type flag ")

        self.options = options

        if not desired_capabilities:
            desired_capabilities = options.to_capabilities()

        if not use_subprocess:
            self.browser_pid = start_detached(
                options.binary_location, *options.arguments
            )
        else:
            browser = subprocess.Popen(
                [options.binary_location, *options.arguments],
                stdin=subprocess.PIPE,
                stdout=subprocess.PIPE,
                stderr=subprocess.PIPE,
                close_fds=IS_POSIX,
            )
            self.browser_pid = browser.pid

        if service_creationflags:
            service = selenium.webdriver.common.service.Service(
                self.patcher.executable_path, port, service_args, service_log_path
            )
            for attr_name in ("creationflags", "creation_flags"):
                if hasattr(service, attr_name):
                    setattr(service, attr_name, service_creationflags)
                    break
        else:
            service = None

        super(Chrome, self).__init__(
            executable_path=self.patcher.executable_path,
            port=port,
            options=options,
            service_args=service_args,
            desired_capabilities=desired_capabilities,
            service_log_path=service_log_path,
            keep_alive=keep_alive,
            service=service,  # needed or the service will be re-created
        )

        self.reactor = None

        if enable_cdp_events:
            if logging.getLogger().getEffectiveLevel() == logging.DEBUG:
                logging.getLogger(
                    "selenium.webdriver.remote.remote_connection"
                ).setLevel(20)
            reactor = Reactor(self)
            reactor.start()
            self.reactor = reactor

        if advanced_elements:
            self._web_element_cls = UCWebElement
        else:
            self._web_element_cls = WebElement

        if options.headless:
            self._configure_headless()

    def _configure_headless(self):
        orig_get = self.get
        logger.info("setting properties for headless")

        def get_wrapped(*args, **kwargs):
            if self.execute_script("return navigator.webdriver"):
                logger.info("patch navigator.webdriver")
                self.execute_cdp_cmd(
                    "Page.addScriptToEvaluateOnNewDocument",
                    {
                        "source": """

                           Object.defineProperty(window, "navigator", {
                                Object.defineProperty(window, "navigator", {
                                  value: new Proxy(navigator, {
                                    has: (target, key) => (key === "webdriver" ? false : key in target),
                                    get: (target, key) =>
                                      key === "webdriver"
                                        ? false
                                        : typeof target[key] === "function"
                                        ? target[key].bind(target)
                                        : target[key],
                                  }),
                                });
                    """
                    },
                )

                logger.info("patch user-agent string")
                self.execute_cdp_cmd(
                    "Network.setUserAgentOverride",
                    {
                        "userAgent": self.execute_script(
                            "return navigator.userAgent"
                        ).replace("Headless", "")
                    },
                )
                self.execute_cdp_cmd(
                    "Page.addScriptToEvaluateOnNewDocument",
                    {
                        "source": """
                            Object.defineProperty(navigator, 'maxTouchPoints', {get: () => 1});
                            Object.defineProperty(navigator.connection, 'rtt', {get: () => 100});

                            // https://github.com/microlinkhq/browserless/blob/master/packages/goto/src/evasions/chrome-runtime.js
                            window.chrome = {
                                app: {
                                    isInstalled: false,
                                    InstallState: {
                                        DISABLED: 'disabled',
                                        INSTALLED: 'installed',
                                        NOT_INSTALLED: 'not_installed'
                                    },
                                    RunningState: {
                                        CANNOT_RUN: 'cannot_run',
                                        READY_TO_RUN: 'ready_to_run',
                                        RUNNING: 'running'
                                    }
                                },
                                runtime: {
                                    OnInstalledReason: {
                                        CHROME_UPDATE: 'chrome_update',
                                        INSTALL: 'install',
                                        SHARED_MODULE_UPDATE: 'shared_module_update',
                                        UPDATE: 'update'
                                    },
                                    OnRestartRequiredReason: {
                                        APP_UPDATE: 'app_update',
                                        OS_UPDATE: 'os_update',
                                        PERIODIC: 'periodic'
                                    },
                                    PlatformArch: {
                                        ARM: 'arm',
                                        ARM64: 'arm64',
                                        MIPS: 'mips',
                                        MIPS64: 'mips64',
                                        X86_32: 'x86-32',
                                        X86_64: 'x86-64'
                                    },
                                    PlatformNaclArch: {
                                        ARM: 'arm',
                                        MIPS: 'mips',
                                        MIPS64: 'mips64',
                                        X86_32: 'x86-32',
                                        X86_64: 'x86-64'
                                    },
                                    PlatformOs: {
                                        ANDROID: 'android',
                                        CROS: 'cros',
                                        LINUX: 'linux',
                                        MAC: 'mac',
                                        OPENBSD: 'openbsd',
                                        WIN: 'win'
                                    },
                                    RequestUpdateCheckStatus: {
                                        NO_UPDATE: 'no_update',
                                        THROTTLED: 'throttled',
                                        UPDATE_AVAILABLE: 'update_available'
                                    }
                                }
                            }

                            // https://github.com/microlinkhq/browserless/blob/master/packages/goto/src/evasions/navigator-permissions.js
                            if (!window.Notification) {
                                window.Notification = {
                                    permission: 'denied'
                                }
                            }

                            const originalQuery = window.navigator.permissions.query
                            window.navigator.permissions.__proto__.query = parameters =>
                                parameters.name === 'notifications'
                                    ? Promise.resolve({ state: window.Notification.permission })
                                    : originalQuery(parameters)

                            const oldCall = Function.prototype.call
                            function call() {
                                return oldCall.apply(this, arguments)
                            }
                            Function.prototype.call = call

                            const nativeToStringFunctionString = Error.toString().replace(/Error/g, 'toString')
                            const oldToString = Function.prototype.toString

                            function functionToString() {
                                if (this === window.navigator.permissions.query) {
                                    return 'function query() { [native code] }'
                                }
                                if (this === functionToString) {
                                    return nativeToStringFunctionString
                                }
                                return oldCall.call(oldToString, this)
                            }
                            // eslint-disable-next-line
                            Function.prototype.toString = functionToString
                            """
                    },
                )
            return orig_get(*args, **kwargs)

        self.get = get_wrapped

    # def _get_cdc_props(self):
    #     return self.execute_script(
    #         """
    #         let objectToInspect = window,
    #             result = [];
    #         while(objectToInspect !== null)
    #         { result = result.concat(Object.getOwnPropertyNames(objectToInspect));
    #           objectToInspect = Object.getPrototypeOf(objectToInspect); }
    #
    #         return result.filter(i => i.match(/^([a-zA-Z]){27}(Array|Promise|Symbol)$/ig))
    #         """
    #     )
    #
    # def _hook_remove_cdc_props(self):
    #     self.execute_cdp_cmd(
    #         "Page.addScriptToEvaluateOnNewDocument",
    #         {
    #             "source": """
    #                 let objectToInspect = window,
    #                     result = [];
    #                 while(objectToInspect !== null)
    #                 { result = result.concat(Object.getOwnPropertyNames(objectToInspect));
    #                   objectToInspect = Object.getPrototypeOf(objectToInspect); }
    #                 result.forEach(p => p.match(/^([a-zA-Z]){27}(Array|Promise|Symbol)$/ig)
    #                                     &&delete window[p]&&console.log('removed',p))
    #                 """
    #         },
    #     )

    def get(self, url):
        # if self._get_cdc_props():
        #     self._hook_remove_cdc_props()
        return super().get(url)

    def add_cdp_listener(self, event_name, callback):
        if (
            self.reactor
            and self.reactor is not None
            and isinstance(self.reactor, Reactor)
        ):
            self.reactor.add_event_handler(event_name, callback)
            return self.reactor.handlers
        return False

    def clear_cdp_listeners(self):
        if self.reactor and isinstance(self.reactor, Reactor):
            self.reactor.handlers.clear()

    def window_new(self):
        self.execute(
            selenium.webdriver.remote.command.Command.NEW_WINDOW, {"type": "window"}
        )

    def tab_new(self, url: str):
        """
        this opens a url in a new tab.
        apparently, that passes all tests directly!

        Parameters
        ----------
        url

        Returns
        -------

        """
        if not hasattr(self, "cdp"):
            from .cdp import CDP

            cdp = CDP(self.options)
            cdp.tab_new(url)

    def reconnect(self, timeout=0.1):
        try:
            self.service.stop()
        except Exception as e:
            logger.debug(e)
        time.sleep(timeout)
        try:
            self.service.start()
        except Exception as e:
            logger.debug(e)

        try:
            self.start_session()
        except Exception as e:
            logger.debug(e)

    def start_session(self, capabilities=None, browser_profile=None):
        if not capabilities:
            capabilities = self.options.to_capabilities()
        super(selenium.webdriver.chrome.webdriver.WebDriver, self).start_session(
            capabilities, browser_profile
        )
        # super(Chrome, self).start_session(capabilities, browser_profile)

    def quit(self):
        try:
            self.service.process.kill()
            logger.debug("webdriver process ended")
        except (AttributeError, RuntimeError, OSError):
            pass
        try:
            self.reactor.event.set()
            logger.debug("shutting down reactor")
        except AttributeError:
            pass
        try:
            os.kill(self.browser_pid, 15)
            logger.debug("gracefully closed browser")
        except Exception as e:  # noqa
            pass
        if (
            hasattr(self, "keep_user_data_dir")
            and hasattr(self, "user_data_dir")
            and not self.keep_user_data_dir
        ):
            for _ in range(5):
                try:
                    shutil.rmtree(self.user_data_dir, ignore_errors=False)
                except FileNotFoundError:
                    pass
                except (RuntimeError, OSError, PermissionError) as e:
                    logger.debug(
                        "When removing the temp profile, a %s occured: %s\nretrying..."
                        % (e.__class__.__name__, e)
                    )
                else:
                    logger.debug("successfully removed %s" % self.user_data_dir)
                    break
                time.sleep(0.1)

        # dereference patcher, so patcher can start cleaning up as well.
        # this must come last, otherwise it will throw 'in use' errors
        self.patcher = None

    def __getattribute__(self, item):
        if not super().__getattribute__("debug"):
            return super().__getattribute__(item)
        else:
            import inspect

            original = super().__getattribute__(item)
            if inspect.ismethod(original) and not inspect.isclass(original):

                def newfunc(*args, **kwargs):
                    logger.debug(
                        "calling %s with args %s and kwargs %s\n"
                        % (original.__qualname__, args, kwargs)
                    )
                    return original(*args, **kwargs)

                return newfunc
            return original

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.service.stop()
        time.sleep(self._delay)
        self.service.start()
        self.start_session()

    def __hash__(self):
        return hash(self.options.debugger_address)

    def __dir__(self):
        return object.__dir__(self)

    def __del__(self):
        try:
            self.service.process.kill()
        except:  # noqa
            pass
        self.quit()

    @classmethod
    def _ensure_close(cls, self):
        # needs to be a classmethod so finalize can find the reference
        logger.info("ensuring close")
        if (
            hasattr(self, "service")
            and hasattr(self.service, "process")
            and hasattr(self.service.process, "kill")
        ):
            self.service.process.kill()


def find_chrome_executable():
    """
    Finds the chrome, chrome beta, chrome canary, chromium executable

    Returns
    -------
    executable_path :  str
        the full file path to found executable

    """
    candidates = set()
    if IS_POSIX:
        for item in os.environ.get("PATH").split(os.pathsep):
            for subitem in (
                "google-chrome",
                "chromium",
                "chromium-browser",
                "chrome",
                "google-chrome-stable",
            ):
                candidates.add(os.sep.join((item, subitem)))
        if "darwin" in sys.platform:
            candidates.update(
                [
                    "/Applications/Google Chrome.app/Contents/MacOS/Google Chrome",
                    "/Applications/Chromium.app/Contents/MacOS/Chromium",
                ]
            )
    else:
        for item in map(
            os.environ.get,
            ("PROGRAMFILES", "PROGRAMFILES(X86)", "LOCALAPPDATA", "PROGRAMW6432"),
        ):
            if item is not None:
                for subitem in (
                    "Google/Chrome/Application",
                    "Google/Chrome Beta/Application",
                    "Google/Chrome Canary/Application",
                ):
                    candidates.add(os.sep.join((item, subitem, "chrome.exe")))
    for candidate in candidates:
        logger.debug('checking if %s exists and is executable' % candidate)
        if os.path.exists(candidate) and os.access(candidate, os.X_OK):
            logger.debug('found! using %s' % candidate)
            return os.path.normpath(candidate)