Support priv/unpriv image extraction

Optionally add back privileged extraction which can be enabled with
LUET_PRIVILEGED_EXTRACT=true

Signed-off-by: Ettore Di Giacinto <mudler@sabayon.org>

pkg/helpers/imgworker/pull.go

@@ -0,0 +1,129 @@
+package imgworker
+
+// FROM Slightly adapted from genuinetools/img worker
+
+import (
+	"fmt"
+
+	"github.com/containerd/containerd/images"
+	"github.com/containerd/containerd/platforms"
+	"github.com/docker/distribution/reference"
+	"github.com/moby/buildkit/cache"
+	"github.com/moby/buildkit/exporter"
+	imageexporter "github.com/moby/buildkit/exporter/containerimage"
+	"github.com/moby/buildkit/source"
+	"github.com/moby/buildkit/source/containerimage"
+)
+
+// ListedImage represents an image structure returuned from ListImages.
+// It extends containerd/images.Image with extra fields.
+type ListedImage struct {
+	images.Image
+	ContentSize int64
+}
+
+// Pull retrieves an image from a remote registry.
+func (c *Client) Pull(image string) (*ListedImage, error) {
+
+	ctx := c.ctx
+
+	sm, err := c.getSessionManager()
+	if err != nil {
+		return nil, err
+	}
+
+	// Parse the image name and tag.
+	named, err := reference.ParseNormalizedNamed(image)
+	if err != nil {
+		return nil, fmt.Errorf("parsing image name %q failed: %v", image, err)
+	}
+	// Add the latest lag if they did not provide one.
+	named = reference.TagNameOnly(named)
+	image = named.String()
+
+	// Get the identifier for the image.
+	identifier, err := source.NewImageIdentifier(image)
+	if err != nil {
+		return nil, err
+	}
+
+	// Create the worker opts.
+	opt, err := c.createWorkerOpt()
+	if err != nil {
+		return nil, fmt.Errorf("creating worker opt failed: %v", err)
+	}
+
+	cm, err := cache.NewManager(cache.ManagerOpt{
+		Snapshotter:    opt.Snapshotter,
+		MetadataStore:  opt.MetadataStore,
+		ContentStore:   opt.ContentStore,
+		LeaseManager:   opt.LeaseManager,
+		GarbageCollect: opt.GarbageCollect,
+		Applier:        opt.Applier,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	// Create the source for the pull.
+	srcOpt := containerimage.SourceOpt{
+		Snapshotter:   opt.Snapshotter,
+		ContentStore:  opt.ContentStore,
+		Applier:       opt.Applier,
+		CacheAccessor: cm,
+		ImageStore:    opt.ImageStore,
+		RegistryHosts: opt.RegistryHosts,
+		LeaseManager:  opt.LeaseManager,
+	}
+	src, err := containerimage.NewSource(srcOpt)
+	if err != nil {
+		return nil, err
+	}
+	s, err := src.Resolve(ctx, identifier, sm)
+	if err != nil {
+		return nil, err
+	}
+	ref, err := s.Snapshot(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	// Create the exporter for the pull.
+	iw, err := imageexporter.NewImageWriter(imageexporter.WriterOpt{
+		Snapshotter:  opt.Snapshotter,
+		ContentStore: opt.ContentStore,
+		Differ:       opt.Differ,
+	})
+	if err != nil {
+		return nil, err
+	}
+	expOpt := imageexporter.Opt{
+		SessionManager: sm,
+		ImageWriter:    iw,
+		Images:         opt.ImageStore,
+		RegistryHosts:  opt.RegistryHosts,
+		LeaseManager:   opt.LeaseManager,
+	}
+	exp, err := imageexporter.New(expOpt)
+	if err != nil {
+		return nil, err
+	}
+	e, err := exp.Resolve(ctx, map[string]string{"name": image})
+	if err != nil {
+		return nil, err
+	}
+	if _, err := e.Export(ctx, exporter.Source{Ref: ref}); err != nil {
+		return nil, err
+	}
+	// Get the image.
+	img, err := opt.ImageStore.Get(ctx, image)
+	if err != nil {
+		return nil, fmt.Errorf("getting image %s from image store failed: %v", image, err)
+	}
+	size, err := img.Size(ctx, opt.ContentStore, platforms.Default())
+	if err != nil {
+		return nil, fmt.Errorf("calculating size of image %s failed: %v", img.Name, err)
+	}
+
+	return &ListedImage{Image: img, ContentSize: size}, nil
+}