82 lines
2.7 KiB
Python
82 lines
2.7 KiB
Python
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from django.core.exceptions import ImproperlyConfigured, SuspiciousFileOperation
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from django.template.utils import get_app_template_dirs
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from django.utils._os import safe_join
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from django.utils.functional import cached_property
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class BaseEngine:
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# Core methods: engines have to provide their own implementation
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# (except for from_string which is optional).
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def __init__(self, params):
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"""
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Initialize the template engine.
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`params` is a dict of configuration settings.
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"""
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params = params.copy()
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self.name = params.pop("NAME")
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self.dirs = list(params.pop("DIRS"))
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self.app_dirs = params.pop("APP_DIRS")
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if params:
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raise ImproperlyConfigured(
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"Unknown parameters: {}".format(", ".join(params))
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)
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@property
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def app_dirname(self):
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raise ImproperlyConfigured(
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"{} doesn't support loading templates from installed "
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"applications.".format(self.__class__.__name__)
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)
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def from_string(self, template_code):
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"""
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Create and return a template for the given source code.
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This method is optional.
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"""
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raise NotImplementedError(
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"subclasses of BaseEngine should provide a from_string() method"
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)
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def get_template(self, template_name):
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"""
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Load and return a template for the given name.
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Raise TemplateDoesNotExist if no such template exists.
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"""
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raise NotImplementedError(
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"subclasses of BaseEngine must provide a get_template() method"
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)
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# Utility methods: they are provided to minimize code duplication and
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# security issues in third-party backends.
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@cached_property
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def template_dirs(self):
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"""
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Return a list of directories to search for templates.
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"""
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# Immutable return value because it's cached and shared by callers.
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template_dirs = tuple(self.dirs)
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if self.app_dirs:
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template_dirs += get_app_template_dirs(self.app_dirname)
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return template_dirs
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def iter_template_filenames(self, template_name):
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"""
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Iterate over candidate files for template_name.
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Ignore files that don't lie inside configured template dirs to avoid
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directory traversal attacks.
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"""
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for template_dir in self.template_dirs:
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try:
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yield safe_join(template_dir, template_name)
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except SuspiciousFileOperation:
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# The joined path was located outside of this template_dir
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# (it might be inside another one, so this isn't fatal).
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pass
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