Function mountsToLayerAndParents

plugins/diff/windows/windows.go:323–353

(mounts []mount.Mount)

}

func mountsToLayerAndParents(mounts []mount.Mount) (string, []string, error) {
	if len(mounts) != 1 {
		return "", nil, fmt.Errorf("number of mounts should always be 1 for Windows layers: %w", errdefs.ErrInvalidArgument)
	}
	mnt := mounts[0]

	if mnt.Type != "windows-layer" {
		// This is a special case error. When this is received the diff service
		// will attempt the next differ in the chain which for Windows is the
		// lcow differ that we want.
		return "", nil, fmt.Errorf("windowsDiff does not support layer type %s: %w", mnt.Type, errdefs.ErrNotImplemented)
	}

	parentLayerPaths, err := mnt.GetParentPaths()
	if err != nil {
		return "", nil, err
	}

	if mnt.ReadOnly() {
		if len(parentLayerPaths) == 0 {
			// rootfs.CreateDiff creates a new, empty View to diff against,
			// when diffing something with no parent.
			// This makes perfect sense for a walking Diff, but for WCOW,
			// we have to recognise this as "diff against nothing"
			return "", nil, nil
		}
		// Ignore the dummy sandbox.
		return parentLayerPaths[0], parentLayerPaths[1:], nil
	}
	return mnt.Source, parentLayerPaths, nil
}

// mountPairToLayerStack ensures that the two sets of mount-lists are actually a correct
// parent-and-child, or orphan-and-empty-list, and return the full list of layers, starting