webdav-handler-rs/doc/APPLE-Finder-hints.md

APPLE-FINDER-HINTS

The Apple Finder (and other subsystems) seem to probe for a few files at the root of the filesystems to get a hint about the behaviour they should show processing this filesystem.

It also looks for files with extra localization information in every directory, and for resource fork data (the ._ files).

FILES

• .metadata_never_index prevents the system from indexing all of the data
• .ql_disablethumbnails prevent the system from downloading all files that look like an image or a video to create a thumbnail
• .ql_disablecache not really sure but it sounds useful

The .ql_ files are configuration for the "QuickLook" functionality of the Finder.

The .metadata_never_index file appears to be a hint for the Spotlight indexing system.

Additionally, the Finder probes for a .localized file in every directory it encounters, and it does a PROPSTAT for every file in the directory prefixed with ._.

OPTIMIZATIONS

For a macOS client we return the metadata for a zero-sized file if it does a PROPSTAT of /.metadata_never_index or /.ql_disablethumbnails.

We always return a 404 Not Found for a PROPSTAT of any .localized file.

Furthermore, we disallow moving, removing etc of those files. The files do not show up in a PROPSTAT of the rootdirectory.

If a PROPFIND with Depth: 1 is done on a directory, we add the directory pathname to an LRU cache, and the pathname of each file of which the name starts with ._. Since we then know which ._ files exist, it is easy to return a fast 404 for PROPSTAT request for ._ files that do not exist. The cache is kept consistent by checking the timestamp on the parent directory, and a timeout.