imagetools inspect: add --format flag

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

vendor/github.com/moby/buildkit/util/contentutil/copy.go

@@ -0,0 +1,94 @@
+package contentutil
+
+import (
+	"context"
+	"io"
+	"sync"
+
+	"github.com/containerd/containerd/content"
+	"github.com/containerd/containerd/images"
+	"github.com/moby/buildkit/util/resolver/limited"
+	"github.com/moby/buildkit/util/resolver/retryhandler"
+	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/pkg/errors"
+)
+
+func Copy(ctx context.Context, ingester content.Ingester, provider content.Provider, desc ocispecs.Descriptor, ref string, logger func([]byte)) error {
+	if _, err := retryhandler.New(limited.FetchHandler(ingester, &localFetcher{provider}, ref), logger)(ctx, desc); err != nil {
+		return err
+	}
+	return nil
+}
+
+type localFetcher struct {
+	content.Provider
+}
+
+func (f *localFetcher) Fetch(ctx context.Context, desc ocispecs.Descriptor) (io.ReadCloser, error) {
+	r, err := f.Provider.ReaderAt(ctx, desc)
+	if err != nil {
+		return nil, err
+	}
+	return &rc{ReaderAt: r}, nil
+}
+
+type rc struct {
+	content.ReaderAt
+	offset int64
+}
+
+func (r *rc) Read(b []byte) (int, error) {
+	n, err := r.ReadAt(b, r.offset)
+	r.offset += int64(n)
+	if n > 0 && err == io.EOF {
+		err = nil
+	}
+	return n, err
+}
+
+func (r *rc) Seek(offset int64, whence int) (int64, error) {
+	switch whence {
+	case io.SeekStart:
+		r.offset = offset
+	case io.SeekCurrent:
+		r.offset += offset
+	case io.SeekEnd:
+		r.offset = r.Size() - offset
+	}
+	return r.offset, nil
+}
+
+func CopyChain(ctx context.Context, ingester content.Ingester, provider content.Provider, desc ocispecs.Descriptor) error {
+	var m sync.Mutex
+	manifestStack := []ocispecs.Descriptor{}
+
+	filterHandler := images.HandlerFunc(func(ctx context.Context, desc ocispecs.Descriptor) ([]ocispecs.Descriptor, error) {
+		switch desc.MediaType {
+		case images.MediaTypeDockerSchema2Manifest, ocispecs.MediaTypeImageManifest,
+			images.MediaTypeDockerSchema2ManifestList, ocispecs.MediaTypeImageIndex:
+			m.Lock()
+			manifestStack = append(manifestStack, desc)
+			m.Unlock()
+			return nil, images.ErrStopHandler
+		default:
+			return nil, nil
+		}
+	})
+	handlers := []images.Handler{
+		images.ChildrenHandler(provider),
+		filterHandler,
+		retryhandler.New(limited.FetchHandler(ingester, &localFetcher{provider}, ""), func(_ []byte) {}),
+	}
+
+	if err := images.Dispatch(ctx, images.Handlers(handlers...), nil, desc); err != nil {
+		return errors.WithStack(err)
+	}
+
+	for i := len(manifestStack) - 1; i >= 0; i-- {
+		if err := Copy(ctx, ingester, provider, manifestStack[i], "", nil); err != nil {
+			return errors.WithStack(err)
+		}
+	}
+
+	return nil
+}