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281 lines
9.3 KiB
Python
281 lines
9.3 KiB
Python
2 years ago
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"""
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Serve Shared Static Files
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=========================
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.. autoclass:: SharedDataMiddleware
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:members: is_allowed
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:copyright: 2007 Pallets
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:license: BSD-3-Clause
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"""
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import mimetypes
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import os
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import pkgutil
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import posixpath
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import typing as t
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from datetime import datetime
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from datetime import timezone
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from io import BytesIO
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from time import time
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from zlib import adler32
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from ..http import http_date
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from ..http import is_resource_modified
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from ..security import safe_join
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from ..utils import get_content_type
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from ..wsgi import get_path_info
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from ..wsgi import wrap_file
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_TOpener = t.Callable[[], t.Tuple[t.IO[bytes], datetime, int]]
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_TLoader = t.Callable[[t.Optional[str]], t.Tuple[t.Optional[str], t.Optional[_TOpener]]]
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if t.TYPE_CHECKING:
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from _typeshed.wsgi import StartResponse
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from _typeshed.wsgi import WSGIApplication
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from _typeshed.wsgi import WSGIEnvironment
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class SharedDataMiddleware:
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"""A WSGI middleware which provides static content for development
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environments or simple server setups. Its usage is quite simple::
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import os
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from werkzeug.middleware.shared_data import SharedDataMiddleware
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app = SharedDataMiddleware(app, {
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'/shared': os.path.join(os.path.dirname(__file__), 'shared')
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})
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The contents of the folder ``./shared`` will now be available on
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``http://example.com/shared/``. This is pretty useful during development
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because a standalone media server is not required. Files can also be
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mounted on the root folder and still continue to use the application because
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the shared data middleware forwards all unhandled requests to the
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application, even if the requests are below one of the shared folders.
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If `pkg_resources` is available you can also tell the middleware to serve
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files from package data::
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app = SharedDataMiddleware(app, {
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'/static': ('myapplication', 'static')
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})
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This will then serve the ``static`` folder in the `myapplication`
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Python package.
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The optional `disallow` parameter can be a list of :func:`~fnmatch.fnmatch`
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rules for files that are not accessible from the web. If `cache` is set to
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`False` no caching headers are sent.
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Currently the middleware does not support non-ASCII filenames. If the
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encoding on the file system happens to match the encoding of the URI it may
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work but this could also be by accident. We strongly suggest using ASCII
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only file names for static files.
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The middleware will guess the mimetype using the Python `mimetype`
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module. If it's unable to figure out the charset it will fall back
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to `fallback_mimetype`.
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:param app: the application to wrap. If you don't want to wrap an
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application you can pass it :exc:`NotFound`.
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:param exports: a list or dict of exported files and folders.
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:param disallow: a list of :func:`~fnmatch.fnmatch` rules.
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:param cache: enable or disable caching headers.
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:param cache_timeout: the cache timeout in seconds for the headers.
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:param fallback_mimetype: The fallback mimetype for unknown files.
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.. versionchanged:: 1.0
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The default ``fallback_mimetype`` is
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``application/octet-stream``. If a filename looks like a text
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mimetype, the ``utf-8`` charset is added to it.
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.. versionadded:: 0.6
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Added ``fallback_mimetype``.
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.. versionchanged:: 0.5
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Added ``cache_timeout``.
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"""
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def __init__(
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self,
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app: "WSGIApplication",
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exports: t.Union[
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t.Dict[str, t.Union[str, t.Tuple[str, str]]],
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t.Iterable[t.Tuple[str, t.Union[str, t.Tuple[str, str]]]],
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],
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disallow: None = None,
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cache: bool = True,
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cache_timeout: int = 60 * 60 * 12,
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fallback_mimetype: str = "application/octet-stream",
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) -> None:
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self.app = app
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self.exports: t.List[t.Tuple[str, _TLoader]] = []
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self.cache = cache
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self.cache_timeout = cache_timeout
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if isinstance(exports, dict):
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exports = exports.items()
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for key, value in exports:
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if isinstance(value, tuple):
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loader = self.get_package_loader(*value)
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elif isinstance(value, str):
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if os.path.isfile(value):
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loader = self.get_file_loader(value)
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else:
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loader = self.get_directory_loader(value)
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else:
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raise TypeError(f"unknown def {value!r}")
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self.exports.append((key, loader))
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if disallow is not None:
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from fnmatch import fnmatch
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self.is_allowed = lambda x: not fnmatch(x, disallow)
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self.fallback_mimetype = fallback_mimetype
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def is_allowed(self, filename: str) -> bool:
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"""Subclasses can override this method to disallow the access to
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certain files. However by providing `disallow` in the constructor
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this method is overwritten.
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"""
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return True
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def _opener(self, filename: str) -> _TOpener:
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return lambda: (
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open(filename, "rb"),
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datetime.fromtimestamp(os.path.getmtime(filename), tz=timezone.utc),
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int(os.path.getsize(filename)),
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)
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def get_file_loader(self, filename: str) -> _TLoader:
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return lambda x: (os.path.basename(filename), self._opener(filename))
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def get_package_loader(self, package: str, package_path: str) -> _TLoader:
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load_time = datetime.now(timezone.utc)
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provider = pkgutil.get_loader(package)
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reader = provider.get_resource_reader(package) # type: ignore
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def loader(
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path: t.Optional[str],
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) -> t.Tuple[t.Optional[str], t.Optional[_TOpener]]:
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if path is None:
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return None, None
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path = safe_join(package_path, path)
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if path is None:
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return None, None
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basename = posixpath.basename(path)
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try:
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resource = reader.open_resource(path)
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except OSError:
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return None, None
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if isinstance(resource, BytesIO):
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return (
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basename,
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lambda: (resource, load_time, len(resource.getvalue())),
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)
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return (
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basename,
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lambda: (
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resource,
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datetime.fromtimestamp(
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os.path.getmtime(resource.name), tz=timezone.utc
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),
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os.path.getsize(resource.name),
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),
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)
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return loader
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def get_directory_loader(self, directory: str) -> _TLoader:
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def loader(
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path: t.Optional[str],
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) -> t.Tuple[t.Optional[str], t.Optional[_TOpener]]:
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if path is not None:
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path = safe_join(directory, path)
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if path is None:
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return None, None
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else:
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path = directory
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if os.path.isfile(path):
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return os.path.basename(path), self._opener(path)
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return None, None
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return loader
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def generate_etag(self, mtime: datetime, file_size: int, real_filename: str) -> str:
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real_filename = os.fsencode(real_filename)
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timestamp = mtime.timestamp()
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checksum = adler32(real_filename) & 0xFFFFFFFF
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return f"wzsdm-{timestamp}-{file_size}-{checksum}"
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def __call__(
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self, environ: "WSGIEnvironment", start_response: "StartResponse"
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) -> t.Iterable[bytes]:
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path = get_path_info(environ)
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file_loader = None
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for search_path, loader in self.exports:
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if search_path == path:
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real_filename, file_loader = loader(None)
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if file_loader is not None:
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break
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if not search_path.endswith("/"):
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search_path += "/"
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if path.startswith(search_path):
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real_filename, file_loader = loader(path[len(search_path) :])
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if file_loader is not None:
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break
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if file_loader is None or not self.is_allowed(real_filename): # type: ignore
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return self.app(environ, start_response)
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guessed_type = mimetypes.guess_type(real_filename) # type: ignore
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mime_type = get_content_type(guessed_type[0] or self.fallback_mimetype, "utf-8")
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f, mtime, file_size = file_loader()
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headers = [("Date", http_date())]
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if self.cache:
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timeout = self.cache_timeout
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etag = self.generate_etag(mtime, file_size, real_filename) # type: ignore
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headers += [
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("Etag", f'"{etag}"'),
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("Cache-Control", f"max-age={timeout}, public"),
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]
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if not is_resource_modified(environ, etag, last_modified=mtime):
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f.close()
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start_response("304 Not Modified", headers)
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return []
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headers.append(("Expires", http_date(time() + timeout)))
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else:
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headers.append(("Cache-Control", "public"))
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headers.extend(
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(
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("Content-Type", mime_type),
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("Content-Length", str(file_size)),
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("Last-Modified", http_date(mtime)),
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)
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)
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start_response("200 OK", headers)
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return wrap_file(environ, f)
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