AbsOverlay takes an overlay description string (a path, optionally followed by a colon with an option string, like ":ro" or ":rw"), and replaces any relative path in the description string with an absolute one.

CheckLower checks if the underlying filesystem of the provided path can be used as lower overlay directory.

CheckRootless checks whether the kernel overlay driver supports unprivileged use in a user namespace.

CheckUpper checks if the underlying filesystem of the provided path can be used as an upper overlay directory.

detachAndDelete performs an unmount system call on the specified directory, followed by deletion of the directory and all of its contents.

DetachMount performs an unmount system call on the specified directory.

ensureOverlayDir checks if a directory already exists; if it doesn't, and createIfMissing is true, it attempts to create it with the specified permissions.

IsIncompatible returns if the error corresponds to an incompatible filesystem error.

NewItemFromString takes a string argument, as passed to --overlay, and returns an Item struct describing the requested overlay.

UnprivOverlaysSupported checks whether there is kernel support for unprivileged overlays.

Item represents information about a single overlay item (as specified, for example, in a single --overlay argument).

Set represents a set of overlay directories which will be overlain on top of some filesystem mount point.