gallery-dl/gallery_dl/cookies.py

# -*- coding: utf-8 -*-

# Copyright 2022 Mike Fährmann
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.

# Adapted from yt-dlp's cookies module.
# https://github.com/yt-dlp/yt-dlp/blob/master/yt_dlp/cookies.py

import binascii
import contextlib
import ctypes
import json
import logging
import os
import shutil
import sqlite3
import struct
import subprocess
import sys
import tempfile
from datetime import datetime, timedelta, timezone
from hashlib import pbkdf2_hmac
from http.cookiejar import Cookie
from . import aes, text


SUPPORTED_BROWSERS_CHROMIUM = {
    "brave", "chrome", "chromium", "edge", "opera", "vivaldi"}
SUPPORTED_BROWSERS = SUPPORTED_BROWSERS_CHROMIUM | {"firefox", "safari"}

logger = logging.getLogger("cookies")


def load_cookies(cookiejar, browser_specification):
    browser_name, profile, keyring, container = \
        _parse_browser_specification(*browser_specification)
    if browser_name == "firefox":
        load_cookies_firefox(cookiejar, profile, container)
    elif browser_name == "safari":
        load_cookies_safari(cookiejar, profile)
    elif browser_name in SUPPORTED_BROWSERS_CHROMIUM:
        load_cookies_chrome(cookiejar, browser_name, profile, keyring)
    else:
        raise ValueError("unknown browser '{}'".format(browser_name))


def load_cookies_firefox(cookiejar, profile=None, container=None):
    path, container_id = _firefox_cookies_database(profile, container)
    with DatabaseCopy(path) as db:

        sql = ("SELECT name, value, host, path, isSecure, expiry "
               "FROM moz_cookies")
        parameters = ()

        if container_id is False:
            sql += " WHERE NOT INSTR(originAttributes,'userContextId=')"
        elif container_id:
            sql += " WHERE originAttributes LIKE ? OR originAttributes LIKE ?"
            uid = "%userContextId={}".format(container_id)
            parameters = (uid, uid + "&%")

        set_cookie = cookiejar.set_cookie
        for name, value, domain, path, secure, expires in db.execute(
                sql, parameters):
            set_cookie(Cookie(
                0, name, value, None, False,
                domain, bool(domain), domain.startswith("."),
                path, bool(path), secure, expires, False, None, None, {},
            ))


def load_cookies_safari(cookiejar, profile=None):
    """Ref.: https://github.com/libyal/dtformats/blob
             /main/documentation/Safari%20Cookies.asciidoc
    - This data appears to be out of date
      but the important parts of the database structure is the same
    - There are a few bytes here and there
      which are skipped during parsing
    """
    with _safari_cookies_database() as fp:
        data = fp.read()
    page_sizes, body_start = _safari_parse_cookies_header(data)
    p = DataParser(data[body_start:])
    for page_size in page_sizes:
        _safari_parse_cookies_page(p.read_bytes(page_size), cookiejar)


def load_cookies_chrome(cookiejar, browser_name, profile, keyring):
    config = _get_chromium_based_browser_settings(browser_name)
    path = _chrome_cookies_database(profile, config)
    logger.debug("Extracting cookies from %s", path)

    with DatabaseCopy(path) as db:
        db.text_factory = bytes
        decryptor = get_cookie_decryptor(
            config["directory"], config["keyring"], keyring=keyring)

        try:
            rows = db.execute(
                "SELECT host_key, name, value, encrypted_value, path, "
                "expires_utc, is_secure FROM cookies")
        except sqlite3.OperationalError:
            rows = db.execute(
                "SELECT host_key, name, value, encrypted_value, path, "
                "expires_utc, secure FROM cookies")

        set_cookie = cookiejar.set_cookie
        failed_cookies = unencrypted_cookies = 0

        for domain, name, value, enc_value, path, expires, secure in rows:

            if not value and enc_value:  # encrypted
                value = decryptor.decrypt(enc_value)
                if value is None:
                    failed_cookies += 1
                    continue
            else:
                value = value.decode()
                unencrypted_cookies += 1

            domain = domain.decode()
            path = path.decode()
            name = name.decode()

            set_cookie(Cookie(
                0, name, value, None, False,
                domain, bool(domain), domain.startswith("."),
                path, bool(path), secure, expires, False, None, None, {},
            ))

    if failed_cookies > 0:
        failed_message = " ({} could not be decrypted)".format(failed_cookies)
    else:
        failed_message = ""

    logger.info("Extracted %s cookies from %s%s",
                len(cookiejar), browser_name, failed_message)
    counts = decryptor.cookie_counts.copy()
    counts["unencrypted"] = unencrypted_cookies
    logger.debug("cookie version breakdown: %s", counts)


# --------------------------------------------------------------------
# firefox

def _firefox_cookies_database(profile=None, container=None):
    if not profile:
        search_root = _firefox_browser_directory()
    elif _is_path(profile):
        search_root = profile
    else:
        search_root = os.path.join(_firefox_browser_directory(), profile)

    path = _find_most_recently_used_file(search_root, "cookies.sqlite")
    if path is None:
        raise FileNotFoundError("Unable to find Firefox cookies database in "
                                "{}".format(search_root))
    logger.debug("Extracting cookies from %s", path)

    if container == "none":
        container_id = False
        logger.debug("Only loading cookies not belonging to any container")

    elif container:
        containers_path = os.path.join(
            os.path.dirname(path), "containers.json")

        try:
            with open(containers_path) as containers:
                identities = json.load(containers)["identities"]
        except OSError:
            logger.error("Unable to read Firefox container database at %s",
                         containers_path)
            raise
        except KeyError:
            identities = ()

        for context in identities:
            if container == context.get("name") or container == text.extr(
                    context.get("l10nID", ""), "userContext", ".label"):
                container_id = context["userContextId"]
                break
        else:
            raise ValueError("Unable to find Firefox container {}".format(
                container))
        logger.debug("Only loading cookies from container '%s' (ID %s)",
                     container, container_id)
    else:
        container_id = None

    return path, container_id


def _firefox_browser_directory():
    if sys.platform in ("win32", "cygwin"):
        return os.path.expandvars(r"%APPDATA%\Mozilla\Firefox\Profiles")
    if sys.platform == "darwin":
        return os.path.expanduser("~/Library/Application Support/Firefox")
    return os.path.expanduser("~/.mozilla/firefox")


# --------------------------------------------------------------------
# safari

def _safari_cookies_database():
    try:
        path = os.path.expanduser("~/Library/Cookies/Cookies.binarycookies")
        return open(path, "rb")
    except FileNotFoundError:
        logger.debug("Trying secondary cookie location")
        path = os.path.expanduser("~/Library/Containers/com.apple.Safari/Data"
                                  "/Library/Cookies/Cookies.binarycookies")
        return open(path, "rb")


def _safari_parse_cookies_header(data):
    p = DataParser(data)
    p.expect_bytes(b"cook", "database signature")
    number_of_pages = p.read_uint(big_endian=True)
    page_sizes = [p.read_uint(big_endian=True)
                  for _ in range(number_of_pages)]
    return page_sizes, p.cursor


def _safari_parse_cookies_page(data, jar):
    p = DataParser(data)
    p.expect_bytes(b"\x00\x00\x01\x00", "page signature")
    number_of_cookies = p.read_uint()
    record_offsets = [p.read_uint() for _ in range(number_of_cookies)]
    if number_of_cookies == 0:
        logger.debug("a cookies page of size %s has no cookies", len(data))
        return

    p.skip_to(record_offsets[0], "unknown page header field")

    for i, record_offset in enumerate(record_offsets):
        p.skip_to(record_offset, "space between records")
        record_length = _safari_parse_cookies_record(
            data[record_offset:], jar)
        p.read_bytes(record_length)
    p.skip_to_end("space in between pages")


def _safari_parse_cookies_record(data, cookiejar):
    p = DataParser(data)
    record_size = p.read_uint()
    p.skip(4, "unknown record field 1")
    flags = p.read_uint()
    is_secure = bool(flags & 0x0001)
    p.skip(4, "unknown record field 2")
    domain_offset = p.read_uint()
    name_offset = p.read_uint()
    path_offset = p.read_uint()
    value_offset = p.read_uint()
    p.skip(8, "unknown record field 3")
    expiration_date = _mac_absolute_time_to_posix(p.read_double())
    _creation_date = _mac_absolute_time_to_posix(p.read_double())  # noqa: F841

    try:
        p.skip_to(domain_offset)
        domain = p.read_cstring()

        p.skip_to(name_offset)
        name = p.read_cstring()

        p.skip_to(path_offset)
        path = p.read_cstring()

        p.skip_to(value_offset)
        value = p.read_cstring()
    except UnicodeDecodeError:
        logger.warning("failed to parse Safari cookie "
                       "because UTF-8 decoding failed")
        return record_size

    p.skip_to(record_size, "space at the end of the record")

    cookiejar.set_cookie(Cookie(
        0, name, value, None, False,
        domain, bool(domain), domain.startswith("."),
        path, bool(path), is_secure, expiration_date, False,
        None, None, {},
    ))

    return record_size


# --------------------------------------------------------------------
# chrome

def _chrome_cookies_database(profile, config):
    if profile is None:
        search_root = config["directory"]
    elif _is_path(profile):
        search_root = profile
        config["directory"] = (os.path.dirname(profile)
                               if config["profiles"] else profile)
    elif config["profiles"]:
        search_root = os.path.join(config["directory"], profile)
    else:
        logger.warning("%s does not support profiles", config["browser"])
        search_root = config["directory"]

    path = _find_most_recently_used_file(search_root, "Cookies")
    if path is None:
        raise FileNotFoundError("Unable to find {} cookies database in "
                                "'{}'".format(config["browser"], search_root))
    return path


def _get_chromium_based_browser_settings(browser_name):
    # https://chromium.googlesource.com/chromium
    # /src/+/HEAD/docs/user_data_dir.md
    join = os.path.join

    if sys.platform in ("win32", "cygwin"):
        appdata_local = os.path.expandvars("%LOCALAPPDATA%")
        appdata_roaming = os.path.expandvars("%APPDATA%")
        browser_dir = {
            "brave"   : join(appdata_local,
                             R"BraveSoftware\Brave-Browser\User Data"),
            "chrome"  : join(appdata_local, R"Google\Chrome\User Data"),
            "chromium": join(appdata_local, R"Chromium\User Data"),
            "edge"    : join(appdata_local, R"Microsoft\Edge\User Data"),
            "opera"   : join(appdata_roaming, R"Opera Software\Opera Stable"),
            "vivaldi" : join(appdata_local, R"Vivaldi\User Data"),
        }[browser_name]

    elif sys.platform == "darwin":
        appdata = os.path.expanduser("~/Library/Application Support")
        browser_dir = {
            "brave"   : join(appdata, "BraveSoftware/Brave-Browser"),
            "chrome"  : join(appdata, "Google/Chrome"),
            "chromium": join(appdata, "Chromium"),
            "edge"    : join(appdata, "Microsoft Edge"),
            "opera"   : join(appdata, "com.operasoftware.Opera"),
            "vivaldi" : join(appdata, "Vivaldi"),
        }[browser_name]

    else:
        config = (os.environ.get("XDG_CONFIG_HOME") or
                  os.path.expanduser("~/.config"))
        browser_dir = {
            "brave"   : join(config, "BraveSoftware/Brave-Browser"),
            "chrome"  : join(config, "google-chrome"),
            "chromium": join(config, "chromium"),
            "edge"    : join(config, "microsoft-edge"),
            "opera"   : join(config, "opera"),
            "vivaldi" : join(config, "vivaldi"),
        }[browser_name]

    # Linux keyring names can be determined by snooping on dbus
    # while opening the browser in KDE:
    # dbus-monitor "interface="org.kde.KWallet"" "type=method_return"
    keyring_name = {
        "brave"   : "Brave",
        "chrome"  : "Chrome",
        "chromium": "Chromium",
        "edge"    : "Microsoft Edge" if sys.platform == "darwin" else
                    "Chromium",
        "opera"   : "Opera" if sys.platform == "darwin" else "Chromium",
        "vivaldi" : "Vivaldi" if sys.platform == "darwin" else "Chrome",
    }[browser_name]

    browsers_without_profiles = {"opera"}

    return {
        "browser"  : browser_name,
        "directory": browser_dir,
        "keyring"  : keyring_name,
        "profiles" : browser_name not in browsers_without_profiles
    }


class ChromeCookieDecryptor:
    """
    Overview:

        Linux:
        - cookies are either v10 or v11
            - v10: AES-CBC encrypted with a fixed key
            - v11: AES-CBC encrypted with an OS protected key (keyring)
            - v11 keys can be stored in various places depending on the
              activate desktop environment [2]

        Mac:
        - cookies are either v10 or not v10
            - v10: AES-CBC encrypted with an OS protected key (keyring)
              and more key derivation iterations than linux
            - not v10: "old data" stored as plaintext

        Windows:
        - cookies are either v10 or not v10
            - v10: AES-GCM encrypted with a key which is encrypted with DPAPI
            - not v10: encrypted with DPAPI

    Sources:
    - [1] https://chromium.googlesource.com/chromium/src/+/refs/heads
          /main/components/os_crypt/
    - [2] https://chromium.googlesource.com/chromium/src/+/refs/heads
          /main/components/os_crypt/key_storage_linux.cc
        - KeyStorageLinux::CreateService
    """

    def decrypt(self, encrypted_value):
        raise NotImplementedError("Must be implemented by sub classes")

    @property
    def cookie_counts(self):
        raise NotImplementedError("Must be implemented by sub classes")


def get_cookie_decryptor(browser_root, browser_keyring_name, *, keyring=None):
    if sys.platform in ("win32", "cygwin"):
        return WindowsChromeCookieDecryptor(browser_root)
    elif sys.platform == "darwin":
        return MacChromeCookieDecryptor(browser_keyring_name)
    else:
        return LinuxChromeCookieDecryptor(
            browser_keyring_name, keyring=keyring)


class LinuxChromeCookieDecryptor(ChromeCookieDecryptor):
    def __init__(self, browser_keyring_name, *, keyring=None):
        self._v10_key = self.derive_key(b"peanuts")
        password = _get_linux_keyring_password(browser_keyring_name, keyring)
        self._v11_key = None if password is None else self.derive_key(password)
        self._cookie_counts = {"v10": 0, "v11": 0, "other": 0}

    @staticmethod
    def derive_key(password):
        # values from
        # https://chromium.googlesource.com/chromium/src/+/refs/heads
        # /main/components/os_crypt/os_crypt_linux.cc
        return pbkdf2_sha1(password, salt=b"saltysalt",
                           iterations=1, key_length=16)

    @property
    def cookie_counts(self):
        return self._cookie_counts

    def decrypt(self, encrypted_value):
        version = encrypted_value[:3]
        ciphertext = encrypted_value[3:]

        if version == b"v10":
            self._cookie_counts["v10"] += 1
            return _decrypt_aes_cbc(ciphertext, self._v10_key)

        elif version == b"v11":
            self._cookie_counts["v11"] += 1
            if self._v11_key is None:
                logger.warning("cannot decrypt v11 cookies: no key found")
                return None
            return _decrypt_aes_cbc(ciphertext, self._v11_key)

        else:
            self._cookie_counts["other"] += 1
            return None


class MacChromeCookieDecryptor(ChromeCookieDecryptor):
    def __init__(self, browser_keyring_name):
        password = _get_mac_keyring_password(browser_keyring_name)
        self._v10_key = None if password is None else self.derive_key(password)
        self._cookie_counts = {"v10": 0, "other": 0}

    @staticmethod
    def derive_key(password):
        # values from
        # https://chromium.googlesource.com/chromium/src/+/refs/heads
        # /main/components/os_crypt/os_crypt_mac.mm
        return pbkdf2_sha1(password, salt=b"saltysalt",
                           iterations=1003, key_length=16)

    @property
    def cookie_counts(self):
        return self._cookie_counts

    def decrypt(self, encrypted_value):
        version = encrypted_value[:3]
        ciphertext = encrypted_value[3:]

        if version == b"v10":
            self._cookie_counts["v10"] += 1
            if self._v10_key is None:
                logger.warning("cannot decrypt v10 cookies: no key found")
                return None

            return _decrypt_aes_cbc(ciphertext, self._v10_key)

        else:
            self._cookie_counts["other"] += 1
            # other prefixes are considered "old data",
            # which were stored as plaintext
            # https://chromium.googlesource.com/chromium/src/+/refs/heads
            # /main/components/os_crypt/os_crypt_mac.mm
            return encrypted_value


class WindowsChromeCookieDecryptor(ChromeCookieDecryptor):
    def __init__(self, browser_root):
        self._v10_key = _get_windows_v10_key(browser_root)
        self._cookie_counts = {"v10": 0, "other": 0}

    @property
    def cookie_counts(self):
        return self._cookie_counts

    def decrypt(self, encrypted_value):
        version = encrypted_value[:3]
        ciphertext = encrypted_value[3:]

        if version == b"v10":
            self._cookie_counts["v10"] += 1
            if self._v10_key is None:
                logger.warning("cannot decrypt v10 cookies: no key found")
                return None

            # https://chromium.googlesource.com/chromium/src/+/refs/heads
            # /main/components/os_crypt/os_crypt_win.cc
            #   kNonceLength
            nonce_length = 96 // 8
            # boringssl
            #   EVP_AEAD_AES_GCM_TAG_LEN
            authentication_tag_length = 16

            raw_ciphertext = ciphertext
            nonce = raw_ciphertext[:nonce_length]
            ciphertext = raw_ciphertext[
                nonce_length:-authentication_tag_length]
            authentication_tag = raw_ciphertext[-authentication_tag_length:]

            return _decrypt_aes_gcm(
                ciphertext, self._v10_key, nonce, authentication_tag)

        else:
            self._cookie_counts["other"] += 1
            # any other prefix means the data is DPAPI encrypted
            # https://chromium.googlesource.com/chromium/src/+/refs/heads
            # /main/components/os_crypt/os_crypt_win.cc
            return _decrypt_windows_dpapi(encrypted_value).decode()


# --------------------------------------------------------------------
# keyring

def _choose_linux_keyring():
    """
    https://chromium.googlesource.com/chromium/src/+/refs/heads
    /main/components/os_crypt/key_storage_util_linux.cc
    SelectBackend
    """
    desktop_environment = _get_linux_desktop_environment(os.environ)
    logger.debug("Detected desktop environment: %s", desktop_environment)
    if desktop_environment == DE_KDE:
        return KEYRING_KWALLET
    if desktop_environment == DE_OTHER:
        return KEYRING_BASICTEXT
    return KEYRING_GNOMEKEYRING


def _get_kwallet_network_wallet():
    """ The name of the wallet used to store network passwords.

    https://chromium.googlesource.com/chromium/src/+/refs/heads
    /main/components/os_crypt/kwallet_dbus.cc
    KWalletDBus::NetworkWallet
    which does a dbus call to the following function:
    https://api.kde.org/frameworks/kwallet/html/classKWallet_1_1Wallet.html
    Wallet::NetworkWallet
    """
    default_wallet = "kdewallet"
    try:
        proc, stdout = Popen_communicate(
            "dbus-send", "--session", "--print-reply=literal",
            "--dest=org.kde.kwalletd5",
            "/modules/kwalletd5",
            "org.kde.KWallet.networkWallet"
        )

        if proc.returncode != 0:
            logger.warning("failed to read NetworkWallet")
            return default_wallet
        else:
            network_wallet = stdout.decode().strip()
            logger.debug("NetworkWallet = '%s'", network_wallet)
            return network_wallet
    except Exception as exc:
        logger.warning("exception while obtaining NetworkWallet (%s: %s)",
                       exc.__class__.__name__, exc)
        return default_wallet


def _get_kwallet_password(browser_keyring_name):
    logger.debug("using kwallet-query to obtain password from kwallet")

    if shutil.which("kwallet-query") is None:
        logger.error(
            "kwallet-query command not found. KWallet and kwallet-query "
            "must be installed to read from KWallet. kwallet-query should be "
            "included in the kwallet package for your distribution")
        return b""

    network_wallet = _get_kwallet_network_wallet()

    try:
        proc, stdout = Popen_communicate(
            "kwallet-query",
            "--read-password", browser_keyring_name + " Safe Storage",
            "--folder", browser_keyring_name + " Keys",
            network_wallet,
        )

        if proc.returncode != 0:
            logger.error("kwallet-query failed with return code {}. "
                         "Please consult the kwallet-query man page "
                         "for details".format(proc.returncode))
            return b""

        if stdout.lower().startswith(b"failed to read"):
            logger.debug("Failed to read password from kwallet. "
                         "Using empty string instead")
            # This sometimes occurs in KDE because chrome does not check
            # hasEntry and instead just tries to read the value (which
            # kwallet returns "") whereas kwallet-query checks hasEntry.
            # To verify this:
            # dbus-monitor "interface="org.kde.KWallet"" "type=method_return"
            # while starting chrome.
            # This may be a bug, as the intended behaviour is to generate a
            # random password and store it, but that doesn't matter here.
            return b""
        else:
            logger.debug("password found")
            if stdout[-1:] == b"\n":
                stdout = stdout[:-1]
            return stdout
    except Exception as exc:
        logger.warning("exception running kwallet-query (%s: %s)",
                       exc.__class__.__name__, exc)
        return b""


def _get_gnome_keyring_password(browser_keyring_name):
    try:
        import secretstorage
    except ImportError:
        logger.error("secretstorage not available")
        return b""

    # Gnome keyring does not seem to organise keys in the same way as KWallet,
    # using `dbus-monitor` during startup, it can be observed that chromium
    # lists all keys and presumably searches for its key in the list.
    # It appears that we must do the same.
    # https://github.com/jaraco/keyring/issues/556
    with contextlib.closing(secretstorage.dbus_init()) as con:
        col = secretstorage.get_default_collection(con)
        label = browser_keyring_name + " Safe Storage"
        for item in col.get_all_items():
            if item.get_label() == label:
                return item.get_secret()
        else:
            logger.error("failed to read from keyring")
            return b""


def _get_linux_keyring_password(browser_keyring_name, keyring):
    # Note: chrome/chromium can be run with the following flags
    # to determine which keyring backend it has chosen to use
    # - chromium --enable-logging=stderr --v=1 2>&1 | grep key_storage_
    #
    # Chromium supports --password-store=<basic|gnome|kwallet>
    # so the automatic detection will not be sufficient in all cases.

    if not keyring:
        keyring = _choose_linux_keyring()
    logger.debug("Chosen keyring: %s", keyring)

    if keyring == KEYRING_KWALLET:
        return _get_kwallet_password(browser_keyring_name)
    elif keyring == KEYRING_GNOMEKEYRING:
        return _get_gnome_keyring_password(browser_keyring_name)
    elif keyring == KEYRING_BASICTEXT:
        # when basic text is chosen, all cookies are stored as v10
        # so no keyring password is required
        return None
    assert False, "Unknown keyring " + keyring


def _get_mac_keyring_password(browser_keyring_name):
    logger.debug("using find-generic-password to obtain "
                 "password from OSX keychain")
    try:
        proc, stdout = Popen_communicate(
            "security", "find-generic-password",
            "-w",  # write password to stdout
            "-a", browser_keyring_name,  # match "account"
            "-s", browser_keyring_name + " Safe Storage",  # match "service"
        )

        if stdout[-1:] == b"\n":
            stdout = stdout[:-1]
        return stdout
    except Exception as exc:
        logger.warning("exception running find-generic-password (%s: %s)",
                       exc.__class__.__name__, exc)
        return None


def _get_windows_v10_key(browser_root):
    path = _find_most_recently_used_file(browser_root, "Local State")
    if path is None:
        logger.error("could not find local state file")
        return None
    logger.debug("Found local state file at '%s'", path)
    with open(path, encoding="utf8") as f:
        data = json.load(f)
    try:
        base64_key = data["os_crypt"]["encrypted_key"]
    except KeyError:
        logger.error("no encrypted key in Local State")
        return None
    encrypted_key = binascii.a2b_base64(base64_key)
    prefix = b"DPAPI"
    if not encrypted_key.startswith(prefix):
        logger.error("invalid key")
        return None
    return _decrypt_windows_dpapi(encrypted_key[len(prefix):])


# --------------------------------------------------------------------
# utility

class ParserError(Exception):
    pass


class DataParser:
    def __init__(self, data):
        self.cursor = 0
        self._data = data

    def read_bytes(self, num_bytes):
        if num_bytes < 0:
            raise ParserError("invalid read of {} bytes".format(num_bytes))
        end = self.cursor + num_bytes
        if end > len(self._data):
            raise ParserError("reached end of input")
        data = self._data[self.cursor:end]
        self.cursor = end
        return data

    def expect_bytes(self, expected_value, message):
        value = self.read_bytes(len(expected_value))
        if value != expected_value:
            raise ParserError("unexpected value: {} != {} ({})".format(
                value, expected_value, message))

    def read_uint(self, big_endian=False):
        data_format = ">I" if big_endian else "<I"
        return struct.unpack(data_format, self.read_bytes(4))[0]

    def read_double(self, big_endian=False):
        data_format = ">d" if big_endian else "<d"
        return struct.unpack(data_format, self.read_bytes(8))[0]

    def read_cstring(self):
        buffer = []
        while True:
            c = self.read_bytes(1)
            if c == b"\x00":
                return b"".join(buffer).decode()
            else:
                buffer.append(c)

    def skip(self, num_bytes, description="unknown"):
        if num_bytes > 0:
            logger.debug("skipping {} bytes ({}): {!r}".format(
                num_bytes, description, self.read_bytes(num_bytes)))
        elif num_bytes < 0:
            raise ParserError("invalid skip of {} bytes".format(num_bytes))

    def skip_to(self, offset, description="unknown"):
        self.skip(offset - self.cursor, description)

    def skip_to_end(self, description="unknown"):
        self.skip_to(len(self._data), description)


class DatabaseCopy():

    def __init__(self, path):
        self.path = path
        self.directory = self.database = None

    def __enter__(self):
        try:
            self.directory = tempfile.TemporaryDirectory(prefix="gallery-dl-")
            path_copy = os.path.join(self.directory.name, "copy.sqlite")
            shutil.copyfile(self.path, path_copy)
            self.database = db = sqlite3.connect(
                path_copy, isolation_level=None, check_same_thread=False)
            return db
        except BaseException:
            if self.directory:
                self.directory.cleanup()
            raise

    def __exit__(self, exc, value, tb):
        self.database.close()
        self.directory.cleanup()


def Popen_communicate(*args):
    proc = subprocess.Popen(
        args, stdout=subprocess.PIPE, stderr=subprocess.DEVNULL)
    try:
        stdout, stderr = proc.communicate()
    except BaseException:  # Including KeyboardInterrupt
        proc.kill()
        proc.wait()
        raise
    return proc, stdout


"""
https://chromium.googlesource.com/chromium/src/+/refs/heads
/main/base/nix/xdg_util.h - DesktopEnvironment
"""
DE_OTHER = "other"
DE_CINNAMON = "cinnamon"
DE_GNOME = "gnome"
DE_KDE = "kde"
DE_PANTHEON = "pantheon"
DE_UNITY = "unity"
DE_XFCE = "xfce"


"""
https://chromium.googlesource.com/chromium/src/+/refs/heads
/main/components/os_crypt/key_storage_util_linux.h - SelectedLinuxBackend
"""
KEYRING_KWALLET = "kwallet"
KEYRING_GNOMEKEYRING = "gnomekeyring"
KEYRING_BASICTEXT = "basictext"
SUPPORTED_KEYRINGS = {"kwallet", "gnomekeyring", "basictext"}


def _get_linux_desktop_environment(env):
    """
    Ref: https://chromium.googlesource.com/chromium/src/+/refs/heads
         /main/base/nix/xdg_util.cc - GetDesktopEnvironment
    """
    xdg_current_desktop = env.get("XDG_CURRENT_DESKTOP")
    desktop_session = env.get("DESKTOP_SESSION")

    if xdg_current_desktop:
        xdg_current_desktop = (xdg_current_desktop.partition(":")[0]
                               .strip().lower())

        if xdg_current_desktop == "unity":
            if desktop_session and "gnome-fallback" in desktop_session:
                return DE_GNOME
            else:
                return DE_UNITY
        elif xdg_current_desktop == "gnome":
            return DE_GNOME
        elif xdg_current_desktop == "x-cinnamon":
            return DE_CINNAMON
        elif xdg_current_desktop == "kde":
            return DE_KDE
        elif xdg_current_desktop == "pantheon":
            return DE_PANTHEON
        elif xdg_current_desktop == "xfce":
            return DE_XFCE

    if desktop_session:
        if desktop_session in ("mate", "gnome"):
            return DE_GNOME
        if "kde" in desktop_session:
            return DE_KDE
        if "xfce" in desktop_session:
            return DE_XFCE

    if "GNOME_DESKTOP_SESSION_ID" in env:
        return DE_GNOME
    if "KDE_FULL_SESSION" in env:
        return DE_KDE
    return DE_OTHER


def _mac_absolute_time_to_posix(timestamp):
    return int((datetime(2001, 1, 1, 0, 0, tzinfo=timezone.utc) +
                timedelta(seconds=timestamp)).timestamp())


def pbkdf2_sha1(password, salt, iterations, key_length):
    return pbkdf2_hmac("sha1", password, salt, iterations, key_length)


def _decrypt_aes_cbc(ciphertext, key, initialization_vector=b" " * 16):
    plaintext = aes.unpad_pkcs7(
        aes.aes_cbc_decrypt_bytes(ciphertext, key, initialization_vector))
    try:
        return plaintext.decode()
    except UnicodeDecodeError:
        logger.warning("failed to decrypt cookie (AES-CBC) because UTF-8 "
                       "decoding failed. Possibly the key is wrong?")
        return None


def _decrypt_aes_gcm(ciphertext, key, nonce, authentication_tag):
    try:
        plaintext = aes.aes_gcm_decrypt_and_verify_bytes(
            ciphertext, key, authentication_tag, nonce)
    except ValueError:
        logger.warning("failed to decrypt cookie (AES-GCM) because MAC check "
                       "failed. Possibly the key is wrong?")
        return None

    try:
        return plaintext.decode()
    except UnicodeDecodeError:
        logger.warning("failed to decrypt cookie (AES-GCM) because UTF-8 "
                       "decoding failed. Possibly the key is wrong?")
        return None


def _decrypt_windows_dpapi(ciphertext):
    """
    References:
        - https://docs.microsoft.com/en-us/windows
          /win32/api/dpapi/nf-dpapi-cryptunprotectdata
    """
    from ctypes.wintypes import DWORD

    class DATA_BLOB(ctypes.Structure):
        _fields_ = [("cbData", DWORD),
                    ("pbData", ctypes.POINTER(ctypes.c_char))]

    buffer = ctypes.create_string_buffer(ciphertext)
    blob_in = DATA_BLOB(ctypes.sizeof(buffer), buffer)
    blob_out = DATA_BLOB()
    ret = ctypes.windll.crypt32.CryptUnprotectData(
        ctypes.byref(blob_in),  # pDataIn
        None,  # ppszDataDescr: human readable description of pDataIn
        None,  # pOptionalEntropy: salt?
        None,  # pvReserved: must be NULL
        None,  # pPromptStruct: information about prompts to display
        0,  # dwFlags
        ctypes.byref(blob_out)  # pDataOut
    )
    if not ret:
        logger.warning("failed to decrypt with DPAPI")
        return None

    result = ctypes.string_at(blob_out.pbData, blob_out.cbData)
    ctypes.windll.kernel32.LocalFree(blob_out.pbData)
    return result


def _find_most_recently_used_file(root, filename):
    # if there are multiple browser profiles, take the most recently used one
    paths = []
    for curr_root, dirs, files in os.walk(root):
        for file in files:
            if file == filename:
                paths.append(os.path.join(curr_root, file))
    if not paths:
        return None
    return max(paths, key=lambda path: os.lstat(path).st_mtime)


def _is_path(value):
    return os.path.sep in value


def _parse_browser_specification(
        browser, profile=None, keyring=None, container=None):
    if browser not in SUPPORTED_BROWSERS:
        raise ValueError("unsupported browser '{}'".format(browser))
    if keyring and keyring not in SUPPORTED_KEYRINGS:
        raise ValueError("unsupported keyring '{}'".format(keyring))
    if profile and _is_path(profile):
        profile = os.path.expanduser(profile)
    return browser, profile, keyring, container