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Fix media repository failing when media store path contains symlinks (#11446)
This commit is contained in:
Sean Quah
GitHub
parent
435f044807
commit
858d80bf0f
3 changed files with 176 additions and 41 deletions
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@ -43,47 +43,75 @@ GetPathMethod = TypeVar(
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)
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def _wrap_with_jail_check(func: GetPathMethod) -> GetPathMethod:
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def _wrap_with_jail_check(relative: bool) -> Callable[[GetPathMethod], GetPathMethod]:
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"""Wraps a path-returning method to check that the returned path(s) do not escape
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the media store directory.
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The path-returning method may return either a single path, or a list of paths.
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The check is not expected to ever fail, unless `func` is missing a call to
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`_validate_path_component`, or `_validate_path_component` is buggy.
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Args:
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func: The `MediaFilePaths` method to wrap. The method may return either a single
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path, or a list of paths. Returned paths may be either absolute or relative.
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relative: A boolean indicating whether the wrapped method returns paths relative
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to the media store directory.
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Returns:
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The method, wrapped with a check to ensure that the returned path(s) lie within
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the media store directory. Raises a `ValueError` if the check fails.
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A method which will wrap a path-returning method, adding a check to ensure that
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the returned path(s) lie within the media store directory. The check will raise
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a `ValueError` if it fails.
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"""
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@functools.wraps(func)
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def _wrapped(
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self: "MediaFilePaths", *args: Any, **kwargs: Any
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) -> Union[str, List[str]]:
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path_or_paths = func(self, *args, **kwargs)
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def _wrap_with_jail_check_inner(func: GetPathMethod) -> GetPathMethod:
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@functools.wraps(func)
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def _wrapped(
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self: "MediaFilePaths", *args: Any, **kwargs: Any
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) -> Union[str, List[str]]:
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path_or_paths = func(self, *args, **kwargs)
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if isinstance(path_or_paths, list):
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paths_to_check = path_or_paths
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else:
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paths_to_check = [path_or_paths]
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if isinstance(path_or_paths, list):
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paths_to_check = path_or_paths
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else:
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paths_to_check = [path_or_paths]
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for path in paths_to_check:
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# path may be an absolute or relative path, depending on the method being
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# wrapped. When "appending" an absolute path, `os.path.join` discards the
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# previous path, which is desired here.
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normalized_path = os.path.normpath(os.path.join(self.real_base_path, path))
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if (
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os.path.commonpath([normalized_path, self.real_base_path])
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!= self.real_base_path
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):
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raise ValueError(f"Invalid media store path: {path!r}")
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for path in paths_to_check:
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# Construct the path that will ultimately be used.
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# We cannot guess whether `path` is relative to the media store
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# directory, since the media store directory may itself be a relative
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# path.
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if relative:
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path = os.path.join(self.base_path, path)
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normalized_path = os.path.normpath(path)
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return path_or_paths
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# Now that `normpath` has eliminated `../`s and `./`s from the path,
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# `os.path.commonpath` can be used to check whether it lies within the
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# media store directory.
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if (
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os.path.commonpath([normalized_path, self.normalized_base_path])
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!= self.normalized_base_path
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):
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# The path resolves to outside the media store directory,
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# or `self.base_path` is `.`, which is an unlikely configuration.
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raise ValueError(f"Invalid media store path: {path!r}")
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return cast(GetPathMethod, _wrapped)
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# Note that `os.path.normpath`/`abspath` has a subtle caveat:
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# `a/b/c/../c` will normalize to `a/b/c`, but the former refers to a
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# different path if `a/b/c` is a symlink. That is, the check above is
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# not perfect and may allow a certain restricted subset of untrustworthy
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# paths through. Since the check above is secondary to the main
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# `_validate_path_component` checks, it's less important for it to be
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# perfect.
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#
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# As an alternative, `os.path.realpath` will resolve symlinks, but
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# proves problematic if there are symlinks inside the media store.
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# eg. if `url_store/` is symlinked to elsewhere, its canonical path
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# won't match that of the main media store directory.
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return path_or_paths
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return cast(GetPathMethod, _wrapped)
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return _wrap_with_jail_check_inner
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ALLOWED_CHARACTERS = set(
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@ -127,9 +155,7 @@ class MediaFilePaths:
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def __init__(self, primary_base_path: str):
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self.base_path = primary_base_path
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# The media store directory, with all symlinks resolved.
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self.real_base_path = os.path.realpath(primary_base_path)
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self.normalized_base_path = os.path.normpath(self.base_path)
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# Refuse to initialize if paths cannot be validated correctly for the current
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# platform.
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@ -140,7 +166,7 @@ class MediaFilePaths:
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# for certain homeservers there, since ":"s aren't allowed in paths.
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assert os.name == "posix"
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@_wrap_with_jail_check
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@_wrap_with_jail_check(relative=True)
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def local_media_filepath_rel(self, media_id: str) -> str:
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return os.path.join(
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"local_content",
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@ -151,7 +177,7 @@ class MediaFilePaths:
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local_media_filepath = _wrap_in_base_path(local_media_filepath_rel)
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@_wrap_with_jail_check
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@_wrap_with_jail_check(relative=True)
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def local_media_thumbnail_rel(
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self, media_id: str, width: int, height: int, content_type: str, method: str
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) -> str:
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@ -167,7 +193,7 @@ class MediaFilePaths:
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local_media_thumbnail = _wrap_in_base_path(local_media_thumbnail_rel)
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@_wrap_with_jail_check
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@_wrap_with_jail_check(relative=False)
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def local_media_thumbnail_dir(self, media_id: str) -> str:
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"""
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Retrieve the local store path of thumbnails of a given media_id
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@ -185,7 +211,7 @@ class MediaFilePaths:
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_validate_path_component(media_id[4:]),
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)
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@_wrap_with_jail_check
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@_wrap_with_jail_check(relative=True)
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def remote_media_filepath_rel(self, server_name: str, file_id: str) -> str:
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return os.path.join(
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"remote_content",
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@ -197,7 +223,7 @@ class MediaFilePaths:
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remote_media_filepath = _wrap_in_base_path(remote_media_filepath_rel)
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@_wrap_with_jail_check
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@_wrap_with_jail_check(relative=True)
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def remote_media_thumbnail_rel(
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self,
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server_name: str,
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@ -223,7 +249,7 @@ class MediaFilePaths:
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# Legacy path that was used to store thumbnails previously.
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# Should be removed after some time, when most of the thumbnails are stored
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# using the new path.
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@_wrap_with_jail_check
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@_wrap_with_jail_check(relative=True)
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def remote_media_thumbnail_rel_legacy(
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self, server_name: str, file_id: str, width: int, height: int, content_type: str
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) -> str:
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@ -238,6 +264,7 @@ class MediaFilePaths:
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_validate_path_component(file_name),
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)
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@_wrap_with_jail_check(relative=False)
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def remote_media_thumbnail_dir(self, server_name: str, file_id: str) -> str:
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return os.path.join(
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self.base_path,
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@ -248,7 +275,7 @@ class MediaFilePaths:
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_validate_path_component(file_id[4:]),
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)
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@_wrap_with_jail_check
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@_wrap_with_jail_check(relative=True)
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def url_cache_filepath_rel(self, media_id: str) -> str:
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if NEW_FORMAT_ID_RE.match(media_id):
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# Media id is of the form <DATE><RANDOM_STRING>
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@ -268,7 +295,7 @@ class MediaFilePaths:
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url_cache_filepath = _wrap_in_base_path(url_cache_filepath_rel)
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@_wrap_with_jail_check
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@_wrap_with_jail_check(relative=False)
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def url_cache_filepath_dirs_to_delete(self, media_id: str) -> List[str]:
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"The dirs to try and remove if we delete the media_id file"
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if NEW_FORMAT_ID_RE.match(media_id):
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@ -290,7 +317,7 @@ class MediaFilePaths:
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),
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]
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@_wrap_with_jail_check
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@_wrap_with_jail_check(relative=True)
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def url_cache_thumbnail_rel(
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self, media_id: str, width: int, height: int, content_type: str, method: str
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) -> str:
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@ -318,7 +345,7 @@ class MediaFilePaths:
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url_cache_thumbnail = _wrap_in_base_path(url_cache_thumbnail_rel)
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@_wrap_with_jail_check
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@_wrap_with_jail_check(relative=True)
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def url_cache_thumbnail_directory_rel(self, media_id: str) -> str:
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# Media id is of the form <DATE><RANDOM_STRING>
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# E.g.: 2017-09-28-fsdRDt24DS234dsf
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@ -341,7 +368,7 @@ class MediaFilePaths:
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url_cache_thumbnail_directory_rel
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)
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@_wrap_with_jail_check
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@_wrap_with_jail_check(relative=False)
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def url_cache_thumbnail_dirs_to_delete(self, media_id: str) -> List[str]:
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"The dirs to try and remove if we delete the media_id thumbnails"
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# Media id is of the form <DATE><RANDOM_STRING>
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