640 lines
21 KiB
Python
640 lines
21 KiB
Python
"""Translation helper functions."""
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import functools
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import gettext as gettext_module
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import os
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import re
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import sys
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import warnings
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from asgiref.local import Local
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from django.apps import apps
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from django.conf import settings
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from django.conf.locale import LANG_INFO
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from django.core.exceptions import AppRegistryNotReady
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from django.core.signals import setting_changed
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from django.dispatch import receiver
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from django.utils.regex_helper import _lazy_re_compile
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from django.utils.safestring import SafeData, mark_safe
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from . import to_language, to_locale
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# Translations are cached in a dictionary for every language.
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# The active translations are stored by threadid to make them thread local.
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_translations = {}
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_active = Local()
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# The default translation is based on the settings file.
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_default = None
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# magic gettext number to separate context from message
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CONTEXT_SEPARATOR = "\x04"
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# Maximum number of characters that will be parsed from the Accept-Language
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# header to prevent possible denial of service or memory exhaustion attacks.
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# About 10x longer than the longest value shown on MDN’s Accept-Language page.
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ACCEPT_LANGUAGE_HEADER_MAX_LENGTH = 500
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# Format of Accept-Language header values. From RFC 9110 Sections 12.4.2 and
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# 12.5.4, and RFC 5646 Section 2.1.
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accept_language_re = _lazy_re_compile(
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r"""
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# "en", "en-au", "x-y-z", "es-419", "*"
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([A-Za-z]{1,8}(?:-[A-Za-z0-9]{1,8})*|\*)
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# Optional "q=1.00", "q=0.8"
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(?:\s*;\s*q=(0(?:\.[0-9]{,3})?|1(?:\.0{,3})?))?
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# Multiple accepts per header.
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(?:\s*,\s*|$)
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""",
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re.VERBOSE,
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)
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language_code_re = _lazy_re_compile(
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r"^[a-z]{1,8}(?:-[a-z0-9]{1,8})*(?:@[a-z0-9]{1,20})?$", re.IGNORECASE
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)
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language_code_prefix_re = _lazy_re_compile(r"^/(\w+([@-]\w+){0,2})(/|$)")
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@receiver(setting_changed)
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def reset_cache(*, setting, **kwargs):
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"""
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Reset global state when LANGUAGES setting has been changed, as some
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languages should no longer be accepted.
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"""
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if setting in ("LANGUAGES", "LANGUAGE_CODE"):
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check_for_language.cache_clear()
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get_languages.cache_clear()
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get_supported_language_variant.cache_clear()
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class TranslationCatalog:
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"""
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Simulate a dict for DjangoTranslation._catalog so as multiple catalogs
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with different plural equations are kept separate.
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"""
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def __init__(self, trans=None):
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self._catalogs = [trans._catalog.copy()] if trans else [{}]
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self._plurals = [trans.plural] if trans else [lambda n: int(n != 1)]
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def __getitem__(self, key):
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for cat in self._catalogs:
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try:
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return cat[key]
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except KeyError:
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pass
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raise KeyError(key)
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def __setitem__(self, key, value):
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self._catalogs[0][key] = value
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def __contains__(self, key):
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return any(key in cat for cat in self._catalogs)
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def items(self):
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for cat in self._catalogs:
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yield from cat.items()
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def keys(self):
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for cat in self._catalogs:
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yield from cat.keys()
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def update(self, trans):
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# Merge if plural function is the same, else prepend.
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for cat, plural in zip(self._catalogs, self._plurals):
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if trans.plural.__code__ == plural.__code__:
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cat.update(trans._catalog)
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break
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else:
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self._catalogs.insert(0, trans._catalog.copy())
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self._plurals.insert(0, trans.plural)
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def get(self, key, default=None):
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missing = object()
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for cat in self._catalogs:
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result = cat.get(key, missing)
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if result is not missing:
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return result
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return default
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def plural(self, msgid, num):
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for cat, plural in zip(self._catalogs, self._plurals):
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tmsg = cat.get((msgid, plural(num)))
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if tmsg is not None:
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return tmsg
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raise KeyError
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class DjangoTranslation(gettext_module.GNUTranslations):
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"""
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Set up the GNUTranslations context with regard to output charset.
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This translation object will be constructed out of multiple GNUTranslations
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objects by merging their catalogs. It will construct an object for the
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requested language and add a fallback to the default language, if it's
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different from the requested language.
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"""
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domain = "django"
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def __init__(self, language, domain=None, localedirs=None):
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"""Create a GNUTranslations() using many locale directories"""
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gettext_module.GNUTranslations.__init__(self)
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if domain is not None:
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self.domain = domain
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self.__language = language
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self.__to_language = to_language(language)
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self.__locale = to_locale(language)
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self._catalog = None
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# If a language doesn't have a catalog, use the Germanic default for
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# pluralization: anything except one is pluralized.
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self.plural = lambda n: int(n != 1)
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if self.domain == "django":
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if localedirs is not None:
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# A module-level cache is used for caching 'django' translations
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warnings.warn(
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"localedirs is ignored when domain is 'django'.", RuntimeWarning
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)
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localedirs = None
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self._init_translation_catalog()
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if localedirs:
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for localedir in localedirs:
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translation = self._new_gnu_trans(localedir)
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self.merge(translation)
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else:
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self._add_installed_apps_translations()
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self._add_local_translations()
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if (
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self.__language == settings.LANGUAGE_CODE
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and self.domain == "django"
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and self._catalog is None
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):
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# default lang should have at least one translation file available.
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raise OSError(
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"No translation files found for default language %s."
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% settings.LANGUAGE_CODE
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)
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self._add_fallback(localedirs)
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if self._catalog is None:
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# No catalogs found for this language, set an empty catalog.
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self._catalog = TranslationCatalog()
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def __repr__(self):
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return "<DjangoTranslation lang:%s>" % self.__language
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def _new_gnu_trans(self, localedir, use_null_fallback=True):
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"""
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Return a mergeable gettext.GNUTranslations instance.
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A convenience wrapper. By default gettext uses 'fallback=False'.
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Using param `use_null_fallback` to avoid confusion with any other
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references to 'fallback'.
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"""
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return gettext_module.translation(
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domain=self.domain,
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localedir=localedir,
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languages=[self.__locale],
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fallback=use_null_fallback,
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)
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def _init_translation_catalog(self):
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"""Create a base catalog using global django translations."""
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settingsfile = sys.modules[settings.__module__].__file__
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localedir = os.path.join(os.path.dirname(settingsfile), "locale")
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translation = self._new_gnu_trans(localedir)
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self.merge(translation)
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def _add_installed_apps_translations(self):
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"""Merge translations from each installed app."""
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try:
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app_configs = reversed(apps.get_app_configs())
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except AppRegistryNotReady:
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raise AppRegistryNotReady(
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"The translation infrastructure cannot be initialized before the "
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"apps registry is ready. Check that you don't make non-lazy "
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"gettext calls at import time."
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)
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for app_config in app_configs:
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localedir = os.path.join(app_config.path, "locale")
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if os.path.exists(localedir):
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translation = self._new_gnu_trans(localedir)
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self.merge(translation)
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def _add_local_translations(self):
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"""Merge translations defined in LOCALE_PATHS."""
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for localedir in reversed(settings.LOCALE_PATHS):
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translation = self._new_gnu_trans(localedir)
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self.merge(translation)
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def _add_fallback(self, localedirs=None):
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"""Set the GNUTranslations() fallback with the default language."""
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# Don't set a fallback for the default language or any English variant
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# (as it's empty, so it'll ALWAYS fall back to the default language)
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if self.__language == settings.LANGUAGE_CODE or self.__language.startswith(
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"en"
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):
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return
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if self.domain == "django":
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# Get from cache
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default_translation = translation(settings.LANGUAGE_CODE)
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else:
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default_translation = DjangoTranslation(
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settings.LANGUAGE_CODE, domain=self.domain, localedirs=localedirs
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)
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self.add_fallback(default_translation)
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def merge(self, other):
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"""Merge another translation into this catalog."""
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if not getattr(other, "_catalog", None):
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return # NullTranslations() has no _catalog
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if self._catalog is None:
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# Take plural and _info from first catalog found (generally Django's).
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self.plural = other.plural
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self._info = other._info.copy()
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self._catalog = TranslationCatalog(other)
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else:
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self._catalog.update(other)
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if other._fallback:
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self.add_fallback(other._fallback)
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def language(self):
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"""Return the translation language."""
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return self.__language
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def to_language(self):
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"""Return the translation language name."""
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return self.__to_language
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def ngettext(self, msgid1, msgid2, n):
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try:
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tmsg = self._catalog.plural(msgid1, n)
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except KeyError:
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if self._fallback:
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return self._fallback.ngettext(msgid1, msgid2, n)
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if n == 1:
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tmsg = msgid1
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else:
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tmsg = msgid2
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return tmsg
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def translation(language):
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"""
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Return a translation object in the default 'django' domain.
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"""
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global _translations
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if language not in _translations:
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_translations[language] = DjangoTranslation(language)
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return _translations[language]
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def activate(language):
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"""
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Fetch the translation object for a given language and install it as the
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current translation object for the current thread.
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"""
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if not language:
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return
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_active.value = translation(language)
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def deactivate():
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"""
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Uninstall the active translation object so that further _() calls resolve
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to the default translation object.
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"""
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if hasattr(_active, "value"):
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del _active.value
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def deactivate_all():
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"""
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Make the active translation object a NullTranslations() instance. This is
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useful when we want delayed translations to appear as the original string
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for some reason.
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"""
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_active.value = gettext_module.NullTranslations()
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_active.value.to_language = lambda *args: None
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def get_language():
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"""Return the currently selected language."""
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t = getattr(_active, "value", None)
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if t is not None:
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try:
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return t.to_language()
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except AttributeError:
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pass
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# If we don't have a real translation object, assume it's the default language.
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return settings.LANGUAGE_CODE
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def get_language_bidi():
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"""
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Return selected language's BiDi layout.
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* False = left-to-right layout
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* True = right-to-left layout
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"""
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lang = get_language()
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if lang is None:
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return False
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else:
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base_lang = get_language().split("-")[0]
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return base_lang in settings.LANGUAGES_BIDI
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def catalog():
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"""
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Return the current active catalog for further processing.
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This can be used if you need to modify the catalog or want to access the
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whole message catalog instead of just translating one string.
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"""
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global _default
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t = getattr(_active, "value", None)
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if t is not None:
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return t
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if _default is None:
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_default = translation(settings.LANGUAGE_CODE)
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return _default
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def gettext(message):
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"""
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Translate the 'message' string. It uses the current thread to find the
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translation object to use. If no current translation is activated, the
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message will be run through the default translation object.
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"""
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global _default
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eol_message = message.replace("\r\n", "\n").replace("\r", "\n")
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if eol_message:
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_default = _default or translation(settings.LANGUAGE_CODE)
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translation_object = getattr(_active, "value", _default)
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result = translation_object.gettext(eol_message)
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else:
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# Return an empty value of the corresponding type if an empty message
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# is given, instead of metadata, which is the default gettext behavior.
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result = type(message)("")
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if isinstance(message, SafeData):
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return mark_safe(result)
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return result
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def pgettext(context, message):
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msg_with_ctxt = "%s%s%s" % (context, CONTEXT_SEPARATOR, message)
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result = gettext(msg_with_ctxt)
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if CONTEXT_SEPARATOR in result:
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# Translation not found
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result = message
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elif isinstance(message, SafeData):
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result = mark_safe(result)
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return result
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def gettext_noop(message):
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"""
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Mark strings for translation but don't translate them now. This can be
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used to store strings in global variables that should stay in the base
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language (because they might be used externally) and will be translated
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later.
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"""
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return message
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def do_ntranslate(singular, plural, number, translation_function):
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global _default
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t = getattr(_active, "value", None)
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if t is not None:
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return getattr(t, translation_function)(singular, plural, number)
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if _default is None:
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_default = translation(settings.LANGUAGE_CODE)
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return getattr(_default, translation_function)(singular, plural, number)
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def ngettext(singular, plural, number):
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"""
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Return a string of the translation of either the singular or plural,
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based on the number.
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"""
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return do_ntranslate(singular, plural, number, "ngettext")
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def npgettext(context, singular, plural, number):
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msgs_with_ctxt = (
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"%s%s%s" % (context, CONTEXT_SEPARATOR, singular),
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"%s%s%s" % (context, CONTEXT_SEPARATOR, plural),
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number,
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)
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result = ngettext(*msgs_with_ctxt)
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if CONTEXT_SEPARATOR in result:
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# Translation not found
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result = ngettext(singular, plural, number)
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return result
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def all_locale_paths():
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"""
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Return a list of paths to user-provides languages files.
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"""
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globalpath = os.path.join(
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os.path.dirname(sys.modules[settings.__module__].__file__), "locale"
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)
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app_paths = []
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for app_config in apps.get_app_configs():
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locale_path = os.path.join(app_config.path, "locale")
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if os.path.exists(locale_path):
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app_paths.append(locale_path)
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return [globalpath, *settings.LOCALE_PATHS, *app_paths]
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@functools.lru_cache(maxsize=1000)
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def check_for_language(lang_code):
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"""
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Check whether there is a global language file for the given language
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code. This is used to decide whether a user-provided language is
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available.
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lru_cache should have a maxsize to prevent from memory exhaustion attacks,
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as the provided language codes are taken from the HTTP request. See also
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<https://www.djangoproject.com/weblog/2007/oct/26/security-fix/>.
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"""
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# First, a quick check to make sure lang_code is well-formed (#21458)
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if lang_code is None or not language_code_re.search(lang_code):
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return False
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return any(
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gettext_module.find("django", path, [to_locale(lang_code)]) is not None
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for path in all_locale_paths()
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)
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@functools.lru_cache
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def get_languages():
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"""
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Cache of settings.LANGUAGES in a dictionary for easy lookups by key.
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Convert keys to lowercase as they should be treated as case-insensitive.
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"""
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return {key.lower(): value for key, value in dict(settings.LANGUAGES).items()}
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@functools.lru_cache(maxsize=1000)
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def get_supported_language_variant(lang_code, strict=False):
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"""
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Return the language code that's listed in supported languages, possibly
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selecting a more generic variant. Raise LookupError if nothing is found.
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If `strict` is False (the default), look for a country-specific variant
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when neither the language code nor its generic variant is found.
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lru_cache should have a maxsize to prevent from memory exhaustion attacks,
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as the provided language codes are taken from the HTTP request. See also
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<https://www.djangoproject.com/weblog/2007/oct/26/security-fix/>.
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"""
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if lang_code:
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# If 'zh-hant-tw' is not supported, try special fallback or subsequent
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# language codes i.e. 'zh-hant' and 'zh'.
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possible_lang_codes = [lang_code]
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try:
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possible_lang_codes.extend(LANG_INFO[lang_code]["fallback"])
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except KeyError:
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pass
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i = None
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while (i := lang_code.rfind("-", 0, i)) > -1:
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possible_lang_codes.append(lang_code[:i])
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generic_lang_code = possible_lang_codes[-1]
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supported_lang_codes = get_languages()
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for code in possible_lang_codes:
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if code.lower() in supported_lang_codes and check_for_language(code):
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return code
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if not strict:
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# if fr-fr is not supported, try fr-ca.
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for supported_code in supported_lang_codes:
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if supported_code.startswith(generic_lang_code + "-"):
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return supported_code
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raise LookupError(lang_code)
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def get_language_from_path(path, strict=False):
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"""
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Return the language code if there's a valid language code found in `path`.
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If `strict` is False (the default), look for a country-specific variant
|
||
when neither the language code nor its generic variant is found.
|
||
"""
|
||
regex_match = language_code_prefix_re.match(path)
|
||
if not regex_match:
|
||
return None
|
||
lang_code = regex_match[1]
|
||
try:
|
||
return get_supported_language_variant(lang_code, strict=strict)
|
||
except LookupError:
|
||
return None
|
||
|
||
|
||
def get_language_from_request(request, check_path=False):
|
||
"""
|
||
Analyze the request to find what language the user wants the system to
|
||
show. Only languages listed in settings.LANGUAGES are taken into account.
|
||
If the user requests a sublanguage where we have a main language, we send
|
||
out the main language.
|
||
|
||
If check_path is True, the URL path prefix will be checked for a language
|
||
code, otherwise this is skipped for backwards compatibility.
|
||
"""
|
||
if check_path:
|
||
lang_code = get_language_from_path(request.path_info)
|
||
if lang_code is not None:
|
||
return lang_code
|
||
|
||
lang_code = request.COOKIES.get(settings.LANGUAGE_COOKIE_NAME)
|
||
if (
|
||
lang_code is not None
|
||
and lang_code in get_languages()
|
||
and check_for_language(lang_code)
|
||
):
|
||
return lang_code
|
||
|
||
try:
|
||
return get_supported_language_variant(lang_code)
|
||
except LookupError:
|
||
pass
|
||
|
||
accept = request.META.get("HTTP_ACCEPT_LANGUAGE", "")
|
||
for accept_lang, unused in parse_accept_lang_header(accept):
|
||
if accept_lang == "*":
|
||
break
|
||
|
||
if not language_code_re.search(accept_lang):
|
||
continue
|
||
|
||
try:
|
||
return get_supported_language_variant(accept_lang)
|
||
except LookupError:
|
||
continue
|
||
|
||
try:
|
||
return get_supported_language_variant(settings.LANGUAGE_CODE)
|
||
except LookupError:
|
||
return settings.LANGUAGE_CODE
|
||
|
||
|
||
@functools.lru_cache(maxsize=1000)
|
||
def _parse_accept_lang_header(lang_string):
|
||
"""
|
||
Parse the lang_string, which is the body of an HTTP Accept-Language
|
||
header, and return a tuple of (lang, q-value), ordered by 'q' values.
|
||
|
||
Return an empty tuple if there are any format errors in lang_string.
|
||
"""
|
||
result = []
|
||
pieces = accept_language_re.split(lang_string.lower())
|
||
if pieces[-1]:
|
||
return ()
|
||
for i in range(0, len(pieces) - 1, 3):
|
||
first, lang, priority = pieces[i : i + 3]
|
||
if first:
|
||
return ()
|
||
if priority:
|
||
priority = float(priority)
|
||
else:
|
||
priority = 1.0
|
||
result.append((lang, priority))
|
||
result.sort(key=lambda k: k[1], reverse=True)
|
||
return tuple(result)
|
||
|
||
|
||
def parse_accept_lang_header(lang_string):
|
||
"""
|
||
Parse the value of the Accept-Language header up to a maximum length.
|
||
|
||
The value of the header is truncated to a maximum length to avoid potential
|
||
denial of service and memory exhaustion attacks. Excessive memory could be
|
||
used if the raw value is very large as it would be cached due to the use of
|
||
functools.lru_cache() to avoid repetitive parsing of common header values.
|
||
"""
|
||
# If the header value doesn't exceed the maximum allowed length, parse it.
|
||
if len(lang_string) <= ACCEPT_LANGUAGE_HEADER_MAX_LENGTH:
|
||
return _parse_accept_lang_header(lang_string)
|
||
|
||
# If there is at least one comma in the value, parse up to the last comma
|
||
# before the max length, skipping any truncated parts at the end of the
|
||
# header value.
|
||
if (index := lang_string.rfind(",", 0, ACCEPT_LANGUAGE_HEADER_MAX_LENGTH)) > 0:
|
||
return _parse_accept_lang_header(lang_string[:index])
|
||
|
||
# Don't attempt to parse if there is only one language-range value which is
|
||
# longer than the maximum allowed length and so truncated.
|
||
return ()
|