Method FindRoot

src/cmd/linuxkit/cache/resolvabledescriptor.go:52–72

FindRoot find the root ResolvableDescriptor, representing an Image or Index, for a given imageName.

(imageName string)

// FindRoot find the root ResolvableDescriptor, representing an Image or Index, for
// a given imageName.
func (p *Provider) FindRoot(imageName string) (ResolvableDescriptor, error) {
	matcher := match.Name(imageName)
	rootIndex, err := p.Index()
	// of there is no root index, we are broken
	if err != nil {
		return nil, fmt.Errorf("invalid image cache: %v", err)
	}

	// first try the root tag as an image itself
	images, err := partial.FindImages(rootIndex, matcher)
	if err == nil && len(images) > 0 {
		// if we found the root tag as an image, just use it
		return layoutImage{img: images[0]}, nil
	}
	// we did not find the root tag as an image, it is an index, get the index
	indexes, err := partial.FindIndexes(rootIndex, matcher)
	if err == nil && len(indexes) >= 1 {
		return layoutIndex{idx: indexes[0]}, nil
	}
	return nil, fmt.Errorf("could not find image or index for %s", imageName)
}