The zip archiver handed out its cached directory tree directly. Any
caller which filters a listing in place (as the core listing code
does) altered the cache, so later listings of the same directory could
be corrupted.
Return a copy of the cached listing instead.
A zip containing a file entry whose name refers to the archive's own
root (".", "/" or "") was presented as a single file called "." and
all its other entries disappeared. A file at the root can only be the
archive member the backend was pointed at, so with no root such an
entry is skipped like any other unsafe name.
When a zip archive was mounted at a subdirectory root, readZip used a bare
strings.HasPrefix to decide which entries fell inside the root. This
matched on a raw string prefix rather than a path boundary, so mounting
root "foo" also exposed sibling entries such as "foobar/..." with their
names left uncorrected.
Require a path boundary when filtering by root.
The zip backend mounts a zip file as a browsable Fs. Go's archive/zip
does not sanitize entry names, and readZip applied path.Clean but did
not reject a cleaned name that still pointed outside the archive. A
crafted zip could make rclone copy/sync attempt writes outside the
intended destination.
Sanitize entry names with sanitize.Path - the same check used by
rclone archive extract - skipping any entry with a ".." path
component, whether separated by "/" or "\". A backslash is otherwise
kept as an ordinary character in the name, as archive extract does. It
is up to the destination backend to make names safe for its storage.
Skipped entries are logged as a single count per archive so a crafted
archive with many escaping entries cannot flood the log.
Nick Craig-Wood