bump containers/image to v5.0.0, buildah to v1.11.4

Move to containers/image v5 and containers/buildah to v1.11.4.

Replace an equality check with a type assertion when checking for a
docker.ErrUnauthorizedForCredentials in `podman login`.

Signed-off-by: Nalin Dahyabhai <nalin@redhat.com>

vendor/github.com/containers/image/v5/docker/tarfile/dest.go

@@ -0,0 +1,415 @@
+package tarfile
+
+import (
+	"archive/tar"
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/containers/image/v5/docker/reference"
+	"github.com/containers/image/v5/internal/tmpdir"
+	"github.com/containers/image/v5/manifest"
+	"github.com/containers/image/v5/types"
+	"github.com/opencontainers/go-digest"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+// Destination is a partial implementation of types.ImageDestination for writing to an io.Writer.
+type Destination struct {
+	writer   io.Writer
+	tar      *tar.Writer
+	repoTags []reference.NamedTagged
+	// Other state.
+	blobs  map[digest.Digest]types.BlobInfo // list of already-sent blobs
+	config []byte
+}
+
+// NewDestination returns a tarfile.Destination for the specified io.Writer.
+func NewDestination(dest io.Writer, ref reference.NamedTagged) *Destination {
+	repoTags := []reference.NamedTagged{}
+	if ref != nil {
+		repoTags = append(repoTags, ref)
+	}
+	return &Destination{
+		writer:   dest,
+		tar:      tar.NewWriter(dest),
+		repoTags: repoTags,
+		blobs:    make(map[digest.Digest]types.BlobInfo),
+	}
+}
+
+// AddRepoTags adds the specified tags to the destination's repoTags.
+func (d *Destination) AddRepoTags(tags []reference.NamedTagged) {
+	d.repoTags = append(d.repoTags, tags...)
+}
+
+// SupportedManifestMIMETypes tells which manifest mime types the destination supports
+// If an empty slice or nil it's returned, then any mime type can be tried to upload
+func (d *Destination) SupportedManifestMIMETypes() []string {
+	return []string{
+		manifest.DockerV2Schema2MediaType, // We rely on the types.Image.UpdatedImage schema conversion capabilities.
+	}
+}
+
+// SupportsSignatures returns an error (to be displayed to the user) if the destination certainly can't store signatures.
+// Note: It is still possible for PutSignatures to fail if SupportsSignatures returns nil.
+func (d *Destination) SupportsSignatures(ctx context.Context) error {
+	return errors.Errorf("Storing signatures for docker tar files is not supported")
+}
+
+// AcceptsForeignLayerURLs returns false iff foreign layers in manifest should be actually
+// uploaded to the image destination, true otherwise.
+func (d *Destination) AcceptsForeignLayerURLs() bool {
+	return false
+}
+
+// MustMatchRuntimeOS returns true iff the destination can store only images targeted for the current runtime OS. False otherwise.
+func (d *Destination) MustMatchRuntimeOS() bool {
+	return false
+}
+
+// IgnoresEmbeddedDockerReference returns true iff the destination does not care about Image.EmbeddedDockerReferenceConflicts(),
+// and would prefer to receive an unmodified manifest instead of one modified for the destination.
+// Does not make a difference if Reference().DockerReference() is nil.
+func (d *Destination) IgnoresEmbeddedDockerReference() bool {
+	return false // N/A, we only accept schema2 images where EmbeddedDockerReferenceConflicts() is always false.
+}
+
+// HasThreadSafePutBlob indicates whether PutBlob can be executed concurrently.
+func (d *Destination) HasThreadSafePutBlob() bool {
+	return false
+}
+
+// PutBlob writes contents of stream and returns data representing the result (with all data filled in).
+// inputInfo.Digest can be optionally provided if known; it is not mandatory for the implementation to verify it.
+// inputInfo.Size is the expected length of stream, if known.
+// May update cache.
+// WARNING: The contents of stream are being verified on the fly.  Until stream.Read() returns io.EOF, the contents of the data SHOULD NOT be available
+// to any other readers for download using the supplied digest.
+// If stream.Read() at any time, ESPECIALLY at end of input, returns an error, PutBlob MUST 1) fail, and 2) delete any data stored so far.
+func (d *Destination) PutBlob(ctx context.Context, stream io.Reader, inputInfo types.BlobInfo, cache types.BlobInfoCache, isConfig bool) (types.BlobInfo, error) {
+	// Ouch, we need to stream the blob into a temporary file just to determine the size.
+	// When the layer is decompressed, we also have to generate the digest on uncompressed datas.
+	if inputInfo.Size == -1 || inputInfo.Digest.String() == "" {
+		logrus.Debugf("docker tarfile: input with unknown size, streaming to disk first ...")
+		streamCopy, err := ioutil.TempFile(tmpdir.TemporaryDirectoryForBigFiles(), "docker-tarfile-blob")
+		if err != nil {
+			return types.BlobInfo{}, err
+		}
+		defer os.Remove(streamCopy.Name())
+		defer streamCopy.Close()
+
+		digester := digest.Canonical.Digester()
+		tee := io.TeeReader(stream, digester.Hash())
+		// TODO: This can take quite some time, and should ideally be cancellable using ctx.Done().
+		size, err := io.Copy(streamCopy, tee)
+		if err != nil {
+			return types.BlobInfo{}, err
+		}
+		_, err = streamCopy.Seek(0, os.SEEK_SET)
+		if err != nil {
+			return types.BlobInfo{}, err
+		}
+		inputInfo.Size = size // inputInfo is a struct, so we are only modifying our copy.
+		if inputInfo.Digest == "" {
+			inputInfo.Digest = digester.Digest()
+		}
+		stream = streamCopy
+		logrus.Debugf("... streaming done")
+	}
+
+	// Maybe the blob has been already sent
+	ok, reusedInfo, err := d.TryReusingBlob(ctx, inputInfo, cache, false)
+	if err != nil {
+		return types.BlobInfo{}, err
+	}
+	if ok {
+		return reusedInfo, nil
+	}
+
+	if isConfig {
+		buf, err := ioutil.ReadAll(stream)
+		if err != nil {
+			return types.BlobInfo{}, errors.Wrap(err, "Error reading Config file stream")
+		}
+		d.config = buf
+		if err := d.sendFile(inputInfo.Digest.Hex()+".json", inputInfo.Size, bytes.NewReader(buf)); err != nil {
+			return types.BlobInfo{}, errors.Wrap(err, "Error writing Config file")
+		}
+	} else {
+		// Note that this can't be e.g. filepath.Join(l.Digest.Hex(), legacyLayerFileName); due to the way
+		// writeLegacyLayerMetadata constructs layer IDs differently from inputinfo.Digest values (as described
+		// inside it), most of the layers would end up in subdirectories alone without any metadata; (docker load)
+		// tries to load every subdirectory as an image and fails if the config is missing.  So, keep the layers
+		// in the root of the tarball.
+		if err := d.sendFile(inputInfo.Digest.Hex()+".tar", inputInfo.Size, stream); err != nil {
+			return types.BlobInfo{}, err
+		}
+	}
+	d.blobs[inputInfo.Digest] = types.BlobInfo{Digest: inputInfo.Digest, Size: inputInfo.Size}
+	return types.BlobInfo{Digest: inputInfo.Digest, Size: inputInfo.Size}, nil
+}
+
+// TryReusingBlob checks whether the transport already contains, or can efficiently reuse, a blob, and if so, applies it to the current destination
+// (e.g. if the blob is a filesystem layer, this signifies that the changes it describes need to be applied again when composing a filesystem tree).
+// info.Digest must not be empty.
+// If canSubstitute, TryReusingBlob can use an equivalent equivalent of the desired blob; in that case the returned info may not match the input.
+// If the blob has been succesfully reused, returns (true, info, nil); info must contain at least a digest and size.
+// If the transport can not reuse the requested blob, TryReusingBlob returns (false, {}, nil); it returns a non-nil error only on an unexpected failure.
+// May use and/or update cache.
+func (d *Destination) TryReusingBlob(ctx context.Context, info types.BlobInfo, cache types.BlobInfoCache, canSubstitute bool) (bool, types.BlobInfo, error) {
+	if info.Digest == "" {
+		return false, types.BlobInfo{}, errors.Errorf("Can not check for a blob with unknown digest")
+	}
+	if blob, ok := d.blobs[info.Digest]; ok {
+		return true, types.BlobInfo{Digest: info.Digest, Size: blob.Size}, nil
+	}
+	return false, types.BlobInfo{}, nil
+}
+
+func (d *Destination) createRepositoriesFile(rootLayerID string) error {
+	repositories := map[string]map[string]string{}
+	for _, repoTag := range d.repoTags {
+		if val, ok := repositories[repoTag.Name()]; ok {
+			val[repoTag.Tag()] = rootLayerID
+		} else {
+			repositories[repoTag.Name()] = map[string]string{repoTag.Tag(): rootLayerID}
+		}
+	}
+
+	b, err := json.Marshal(repositories)
+	if err != nil {
+		return errors.Wrap(err, "Error marshaling repositories")
+	}
+	if err := d.sendBytes(legacyRepositoriesFileName, b); err != nil {
+		return errors.Wrap(err, "Error writing config json file")
+	}
+	return nil
+}
+
+// PutManifest writes manifest to the destination.
+// The instanceDigest value is expected to always be nil, because this transport does not support manifest lists, so
+// there can be no secondary manifests.
+// FIXME? This should also receive a MIME type if known, to differentiate between schema versions.
+// If the destination is in principle available, refuses this manifest type (e.g. it does not recognize the schema),
+// but may accept a different manifest type, the returned error must be an ManifestTypeRejectedError.
+func (d *Destination) PutManifest(ctx context.Context, m []byte, instanceDigest *digest.Digest) error {
+	if instanceDigest != nil {
+		return errors.New(`Manifest lists are not supported for docker tar files`)
+	}
+	// We do not bother with types.ManifestTypeRejectedError; our .SupportedManifestMIMETypes() above is already providing only one alternative,
+	// so the caller trying a different manifest kind would be pointless.
+	var man manifest.Schema2
+	if err := json.Unmarshal(m, &man); err != nil {
+		return errors.Wrap(err, "Error parsing manifest")
+	}
+	if man.SchemaVersion != 2 || man.MediaType != manifest.DockerV2Schema2MediaType {
+		return errors.Errorf("Unsupported manifest type, need a Docker schema 2 manifest")
+	}
+
+	layerPaths, lastLayerID, err := d.writeLegacyLayerMetadata(man.LayersDescriptors)
+	if err != nil {
+		return err
+	}
+
+	if len(man.LayersDescriptors) > 0 {
+		if err := d.createRepositoriesFile(lastLayerID); err != nil {
+			return err
+		}
+	}
+
+	repoTags := []string{}
+	for _, tag := range d.repoTags {
+		// For github.com/docker/docker consumers, this works just as well as
+		//   refString := ref.String()
+		// because when reading the RepoTags strings, github.com/docker/docker/reference
+		// normalizes both of them to the same value.
+		//
+		// Doing it this way to include the normalized-out `docker.io[/library]` does make
+		// a difference for github.com/projectatomic/docker consumers, with the
+		// “Add --add-registry and --block-registry options to docker daemon” patch.
+		// These consumers treat reference strings which include a hostname and reference
+		// strings without a hostname differently.
+		//
+		// Using the host name here is more explicit about the intent, and it has the same
+		// effect as (docker pull) in projectatomic/docker, which tags the result using
+		// a hostname-qualified reference.
+		// See https://github.com/containers/image/issues/72 for a more detailed
+		// analysis and explanation.
+		refString := fmt.Sprintf("%s:%s", tag.Name(), tag.Tag())
+		repoTags = append(repoTags, refString)
+	}
+
+	items := []ManifestItem{{
+		Config:       man.ConfigDescriptor.Digest.Hex() + ".json",
+		RepoTags:     repoTags,
+		Layers:       layerPaths,
+		Parent:       "",
+		LayerSources: nil,
+	}}
+	itemsBytes, err := json.Marshal(&items)
+	if err != nil {
+		return err
+	}
+
+	// FIXME? Do we also need to support the legacy format?
+	return d.sendBytes(manifestFileName, itemsBytes)
+}
+
+// writeLegacyLayerMetadata writes legacy VERSION and configuration files for all layers
+func (d *Destination) writeLegacyLayerMetadata(layerDescriptors []manifest.Schema2Descriptor) (layerPaths []string, lastLayerID string, err error) {
+	var chainID digest.Digest
+	lastLayerID = ""
+	for i, l := range layerDescriptors {
+		// This chainID value matches the computation in docker/docker/layer.CreateChainID …
+		if chainID == "" {
+			chainID = l.Digest
+		} else {
+			chainID = digest.Canonical.FromString(chainID.String() + " " + l.Digest.String())
+		}
+		// … but note that this image ID does not match docker/docker/image/v1.CreateID. At least recent
+		// versions allocate new IDs on load, as long as the IDs we use are unique / cannot loop.
+		//
+		// Overall, the goal of computing a digest dependent on the full history is to avoid reusing an image ID
+		// (and possibly creating a loop in the "parent" links) if a layer with the same DiffID appears two or more
+		// times in layersDescriptors.  The ChainID values are sufficient for this, the v1.CreateID computation
+		// which also mixes in the full image configuration seems unnecessary, at least as long as we are storing
+		// only a single image per tarball, i.e. all DiffID prefixes are unique (can’t differ only with
+		// configuration).
+		layerID := chainID.Hex()
+
+		physicalLayerPath := l.Digest.Hex() + ".tar"
+		// The layer itself has been stored into physicalLayerPath in PutManifest.
+		// So, use that path for layerPaths used in the non-legacy manifest
+		layerPaths = append(layerPaths, physicalLayerPath)
+		// ... and create a symlink for the legacy format;
+		if err := d.sendSymlink(filepath.Join(layerID, legacyLayerFileName), filepath.Join("..", physicalLayerPath)); err != nil {
+			return nil, "", errors.Wrap(err, "Error creating layer symbolic link")
+		}
+
+		b := []byte("1.0")
+		if err := d.sendBytes(filepath.Join(layerID, legacyVersionFileName), b); err != nil {
+			return nil, "", errors.Wrap(err, "Error writing VERSION file")
+		}
+
+		// The legacy format requires a config file per layer
+		layerConfig := make(map[string]interface{})
+		layerConfig["id"] = layerID
+
+		// The root layer doesn't have any parent
+		if lastLayerID != "" {
+			layerConfig["parent"] = lastLayerID
+		}
+		// The root layer configuration file is generated by using subpart of the image configuration
+		if i == len(layerDescriptors)-1 {
+			var config map[string]*json.RawMessage
+			err := json.Unmarshal(d.config, &config)
+			if err != nil {
+				return nil, "", errors.Wrap(err, "Error unmarshaling config")
+			}
+			for _, attr := range [7]string{"architecture", "config", "container", "container_config", "created", "docker_version", "os"} {
+				layerConfig[attr] = config[attr]
+			}
+		}
+		b, err := json.Marshal(layerConfig)
+		if err != nil {
+			return nil, "", errors.Wrap(err, "Error marshaling layer config")
+		}
+		if err := d.sendBytes(filepath.Join(layerID, legacyConfigFileName), b); err != nil {
+			return nil, "", errors.Wrap(err, "Error writing config json file")
+		}
+
+		lastLayerID = layerID
+	}
+	return layerPaths, lastLayerID, nil
+}
+
+type tarFI struct {
+	path      string
+	size      int64
+	isSymlink bool
+}
+
+func (t *tarFI) Name() string {
+	return t.path
+}
+func (t *tarFI) Size() int64 {
+	return t.size
+}
+func (t *tarFI) Mode() os.FileMode {
+	if t.isSymlink {
+		return os.ModeSymlink
+	}
+	return 0444
+}
+func (t *tarFI) ModTime() time.Time {
+	return time.Unix(0, 0)
+}
+func (t *tarFI) IsDir() bool {
+	return false
+}
+func (t *tarFI) Sys() interface{} {
+	return nil
+}
+
+// sendSymlink sends a symlink into the tar stream.
+func (d *Destination) sendSymlink(path string, target string) error {
+	hdr, err := tar.FileInfoHeader(&tarFI{path: path, size: 0, isSymlink: true}, target)
+	if err != nil {
+		return nil
+	}
+	logrus.Debugf("Sending as tar link %s -> %s", path, target)
+	return d.tar.WriteHeader(hdr)
+}
+
+// sendBytes sends a path into the tar stream.
+func (d *Destination) sendBytes(path string, b []byte) error {
+	return d.sendFile(path, int64(len(b)), bytes.NewReader(b))
+}
+
+// sendFile sends a file into the tar stream.
+func (d *Destination) sendFile(path string, expectedSize int64, stream io.Reader) error {
+	hdr, err := tar.FileInfoHeader(&tarFI{path: path, size: expectedSize}, "")
+	if err != nil {
+		return nil
+	}
+	logrus.Debugf("Sending as tar file %s", path)
+	if err := d.tar.WriteHeader(hdr); err != nil {
+		return err
+	}
+	// TODO: This can take quite some time, and should ideally be cancellable using a context.Context.
+	size, err := io.Copy(d.tar, stream)
+	if err != nil {
+		return err
+	}
+	if size != expectedSize {
+		return errors.Errorf("Size mismatch when copying %s, expected %d, got %d", path, expectedSize, size)
+	}
+	return nil
+}
+
+// PutSignatures would add the given signatures to the docker tarfile (currently not supported).
+// The instanceDigest value is expected to always be nil, because this transport does not support manifest lists, so
+// there can be no secondary manifests.  MUST be called after PutManifest (signatures reference manifest contents).
+func (d *Destination) PutSignatures(ctx context.Context, signatures [][]byte, instanceDigest *digest.Digest) error {
+	if instanceDigest != nil {
+		return errors.Errorf(`Manifest lists are not supported for docker tar files`)
+	}
+	if len(signatures) != 0 {
+		return errors.Errorf("Storing signatures for docker tar files is not supported")
+	}
+	return nil
+}
+
+// Commit finishes writing data to the underlying io.Writer.
+// It is the caller's responsibility to close it, if necessary.
+func (d *Destination) Commit(ctx context.Context) error {
+	return d.tar.Close()
+}

vendor/github.com/containers/image/v5/docker/tarfile/doc.go

@@ -0,0 +1,3 @@
+// Package tarfile is an internal implementation detail of some transports.
+// Do not use outside of the github.com/containers/image repo!
+package tarfile

vendor/github.com/containers/image/v5/docker/tarfile/src.go

@@ -0,0 +1,490 @@
+package tarfile
+
+import (
+	"archive/tar"
+	"bytes"
+	"context"
+	"encoding/json"
+	"io"
+	"io/ioutil"
+	"os"
+	"path"
+	"sync"
+
+	"github.com/containers/image/v5/internal/tmpdir"
+	"github.com/containers/image/v5/manifest"
+	"github.com/containers/image/v5/pkg/compression"
+	"github.com/containers/image/v5/types"
+	digest "github.com/opencontainers/go-digest"
+	"github.com/pkg/errors"
+)
+
+// Source is a partial implementation of types.ImageSource for reading from tarPath.
+type Source struct {
+	tarPath              string
+	removeTarPathOnClose bool // Remove temp file on close if true
+	// The following data is only available after ensureCachedDataIsPresent() succeeds
+	tarManifest       *ManifestItem // nil if not available yet.
+	configBytes       []byte
+	configDigest      digest.Digest
+	orderedDiffIDList []digest.Digest
+	knownLayers       map[digest.Digest]*layerInfo
+	// Other state
+	generatedManifest []byte    // Private cache for GetManifest(), nil if not set yet.
+	cacheDataLock     sync.Once // Private state for ensureCachedDataIsPresent to make it concurrency-safe
+	cacheDataResult   error     // Private state for ensureCachedDataIsPresent
+}
+
+type layerInfo struct {
+	path string
+	size int64
+}
+
+// TODO: We could add support for multiple images in a single archive, so
+//       that people could use docker-archive:opensuse.tar:opensuse:leap as
+//       the source of an image.
+// 	To do for both the NewSourceFromFile and NewSourceFromStream functions
+
+// NewSourceFromFile returns a tarfile.Source for the specified path.
+func NewSourceFromFile(path string) (*Source, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, errors.Wrapf(err, "error opening file %q", path)
+	}
+	defer file.Close()
+
+	// If the file is already not compressed we can just return the file itself
+	// as a source. Otherwise we pass the stream to NewSourceFromStream.
+	stream, isCompressed, err := compression.AutoDecompress(file)
+	if err != nil {
+		return nil, errors.Wrapf(err, "Error detecting compression for file %q", path)
+	}
+	defer stream.Close()
+	if !isCompressed {
+		return &Source{
+			tarPath: path,
+		}, nil
+	}
+	return NewSourceFromStream(stream)
+}
+
+// NewSourceFromStream returns a tarfile.Source for the specified inputStream,
+// which can be either compressed or uncompressed. The caller can close the
+// inputStream immediately after NewSourceFromFile returns.
+func NewSourceFromStream(inputStream io.Reader) (*Source, error) {
+	// FIXME: use SystemContext here.
+	// Save inputStream to a temporary file
+	tarCopyFile, err := ioutil.TempFile(tmpdir.TemporaryDirectoryForBigFiles(), "docker-tar")
+	if err != nil {
+		return nil, errors.Wrap(err, "error creating temporary file")
+	}
+	defer tarCopyFile.Close()
+
+	succeeded := false
+	defer func() {
+		if !succeeded {
+			os.Remove(tarCopyFile.Name())
+		}
+	}()
+
+	// In order to be compatible with docker-load, we need to support
+	// auto-decompression (it's also a nice quality-of-life thing to avoid
+	// giving users really confusing "invalid tar header" errors).
+	uncompressedStream, _, err := compression.AutoDecompress(inputStream)
+	if err != nil {
+		return nil, errors.Wrap(err, "Error auto-decompressing input")
+	}
+	defer uncompressedStream.Close()
+
+	// Copy the plain archive to the temporary file.
+	//
+	// TODO: This can take quite some time, and should ideally be cancellable
+	//       using a context.Context.
+	if _, err := io.Copy(tarCopyFile, uncompressedStream); err != nil {
+		return nil, errors.Wrapf(err, "error copying contents to temporary file %q", tarCopyFile.Name())
+	}
+	succeeded = true
+
+	return &Source{
+		tarPath:              tarCopyFile.Name(),
+		removeTarPathOnClose: true,
+	}, nil
+}
+
+// tarReadCloser is a way to close the backing file of a tar.Reader when the user no longer needs the tar component.
+type tarReadCloser struct {
+	*tar.Reader
+	backingFile *os.File
+}
+
+func (t *tarReadCloser) Close() error {
+	return t.backingFile.Close()
+}
+
+// openTarComponent returns a ReadCloser for the specific file within the archive.
+// This is linear scan; we assume that the tar file will have a fairly small amount of files (~layers),
+// and that filesystem caching will make the repeated seeking over the (uncompressed) tarPath cheap enough.
+// The caller should call .Close() on the returned stream.
+func (s *Source) openTarComponent(componentPath string) (io.ReadCloser, error) {
+	f, err := os.Open(s.tarPath)
+	if err != nil {
+		return nil, err
+	}
+	succeeded := false
+	defer func() {
+		if !succeeded {
+			f.Close()
+		}
+	}()
+
+	tarReader, header, err := findTarComponent(f, componentPath)
+	if err != nil {
+		return nil, err
+	}
+	if header == nil {
+		return nil, os.ErrNotExist
+	}
+	if header.FileInfo().Mode()&os.ModeType == os.ModeSymlink { // FIXME: untested
+		// We follow only one symlink; so no loops are possible.
+		if _, err := f.Seek(0, os.SEEK_SET); err != nil {
+			return nil, err
+		}
+		// The new path could easily point "outside" the archive, but we only compare it to existing tar headers without extracting the archive,
+		// so we don't care.
+		tarReader, header, err = findTarComponent(f, path.Join(path.Dir(componentPath), header.Linkname))
+		if err != nil {
+			return nil, err
+		}
+		if header == nil {
+			return nil, os.ErrNotExist
+		}
+	}
+
+	if !header.FileInfo().Mode().IsRegular() {
+		return nil, errors.Errorf("Error reading tar archive component %s: not a regular file", header.Name)
+	}
+	succeeded = true
+	return &tarReadCloser{Reader: tarReader, backingFile: f}, nil
+}
+
+// findTarComponent returns a header and a reader matching path within inputFile,
+// or (nil, nil, nil) if not found.
+func findTarComponent(inputFile io.Reader, path string) (*tar.Reader, *tar.Header, error) {
+	t := tar.NewReader(inputFile)
+	for {
+		h, err := t.Next()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return nil, nil, err
+		}
+		if h.Name == path {
+			return t, h, nil
+		}
+	}
+	return nil, nil, nil
+}
+
+// readTarComponent returns full contents of componentPath.
+func (s *Source) readTarComponent(path string) ([]byte, error) {
+	file, err := s.openTarComponent(path)
+	if err != nil {
+		return nil, errors.Wrapf(err, "Error loading tar component %s", path)
+	}
+	defer file.Close()
+	bytes, err := ioutil.ReadAll(file)
+	if err != nil {
+		return nil, err
+	}
+	return bytes, nil
+}
+
+// ensureCachedDataIsPresent loads data necessary for any of the public accessors.
+// It is safe to call this from multi-threaded code.
+func (s *Source) ensureCachedDataIsPresent() error {
+	s.cacheDataLock.Do(func() {
+		s.cacheDataResult = s.ensureCachedDataIsPresentPrivate()
+	})
+	return s.cacheDataResult
+}
+
+// ensureCachedDataIsPresentPrivate is a private implementation detail of ensureCachedDataIsPresent.
+// Call ensureCachedDataIsPresent instead.
+func (s *Source) ensureCachedDataIsPresentPrivate() error {
+	// Read and parse manifest.json
+	tarManifest, err := s.loadTarManifest()
+	if err != nil {
+		return err
+	}
+
+	// Check to make sure length is 1
+	if len(tarManifest) != 1 {
+		return errors.Errorf("Unexpected tar manifest.json: expected 1 item, got %d", len(tarManifest))
+	}
+
+	// Read and parse config.
+	configBytes, err := s.readTarComponent(tarManifest[0].Config)
+	if err != nil {
+		return err
+	}
+	var parsedConfig manifest.Schema2Image // There's a lot of info there, but we only really care about layer DiffIDs.
+	if err := json.Unmarshal(configBytes, &parsedConfig); err != nil {
+		return errors.Wrapf(err, "Error decoding tar config %s", tarManifest[0].Config)
+	}
+
+	knownLayers, err := s.prepareLayerData(&tarManifest[0], &parsedConfig)
+	if err != nil {
+		return err
+	}
+
+	// Success; commit.
+	s.tarManifest = &tarManifest[0]
+	s.configBytes = configBytes
+	s.configDigest = digest.FromBytes(configBytes)
+	s.orderedDiffIDList = parsedConfig.RootFS.DiffIDs
+	s.knownLayers = knownLayers
+	return nil
+}
+
+// loadTarManifest loads and decodes the manifest.json.
+func (s *Source) loadTarManifest() ([]ManifestItem, error) {
+	// FIXME? Do we need to deal with the legacy format?
+	bytes, err := s.readTarComponent(manifestFileName)
+	if err != nil {
+		return nil, err
+	}
+	var items []ManifestItem
+	if err := json.Unmarshal(bytes, &items); err != nil {
+		return nil, errors.Wrap(err, "Error decoding tar manifest.json")
+	}
+	return items, nil
+}
+
+// Close removes resources associated with an initialized Source, if any.
+func (s *Source) Close() error {
+	if s.removeTarPathOnClose {
+		return os.Remove(s.tarPath)
+	}
+	return nil
+}
+
+// LoadTarManifest loads and decodes the manifest.json
+func (s *Source) LoadTarManifest() ([]ManifestItem, error) {
+	return s.loadTarManifest()
+}
+
+func (s *Source) prepareLayerData(tarManifest *ManifestItem, parsedConfig *manifest.Schema2Image) (map[digest.Digest]*layerInfo, error) {
+	// Collect layer data available in manifest and config.
+	if len(tarManifest.Layers) != len(parsedConfig.RootFS.DiffIDs) {
+		return nil, errors.Errorf("Inconsistent layer count: %d in manifest, %d in config", len(tarManifest.Layers), len(parsedConfig.RootFS.DiffIDs))
+	}
+	knownLayers := map[digest.Digest]*layerInfo{}
+	unknownLayerSizes := map[string]*layerInfo{} // Points into knownLayers, a "to do list" of items with unknown sizes.
+	for i, diffID := range parsedConfig.RootFS.DiffIDs {
+		if _, ok := knownLayers[diffID]; ok {
+			// Apparently it really can happen that a single image contains the same layer diff more than once.
+			// In that case, the diffID validation ensures that both layers truly are the same, and it should not matter
+			// which of the tarManifest.Layers paths is used; (docker save) actually makes the duplicates symlinks to the original.
+			continue
+		}
+		layerPath := tarManifest.Layers[i]
+		if _, ok := unknownLayerSizes[layerPath]; ok {
+			return nil, errors.Errorf("Layer tarfile %s used for two different DiffID values", layerPath)
+		}
+		li := &layerInfo{ // A new element in each iteration
+			path: layerPath,
+			size: -1,
+		}
+		knownLayers[diffID] = li
+		unknownLayerSizes[layerPath] = li
+	}
+
+	// Scan the tar file to collect layer sizes.
+	file, err := os.Open(s.tarPath)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+	t := tar.NewReader(file)
+	for {
+		h, err := t.Next()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return nil, err
+		}
+		if li, ok := unknownLayerSizes[h.Name]; ok {
+			// Since GetBlob will decompress layers that are compressed we need
+			// to do the decompression here as well, otherwise we will
+			// incorrectly report the size. Pretty critical, since tools like
+			// umoci always compress layer blobs. Obviously we only bother with
+			// the slower method of checking if it's compressed.
+			uncompressedStream, isCompressed, err := compression.AutoDecompress(t)
+			if err != nil {
+				return nil, errors.Wrapf(err, "Error auto-decompressing %s to determine its size", h.Name)
+			}
+			defer uncompressedStream.Close()
+
+			uncompressedSize := h.Size
+			if isCompressed {
+				uncompressedSize, err = io.Copy(ioutil.Discard, uncompressedStream)
+				if err != nil {
+					return nil, errors.Wrapf(err, "Error reading %s to find its size", h.Name)
+				}
+			}
+			li.size = uncompressedSize
+			delete(unknownLayerSizes, h.Name)
+		}
+	}
+	if len(unknownLayerSizes) != 0 {
+		return nil, errors.Errorf("Some layer tarfiles are missing in the tarball") // This could do with a better error reporting, if this ever happened in practice.
+	}
+
+	return knownLayers, nil
+}
+
+// GetManifest returns the image's manifest along with its MIME type (which may be empty when it can't be determined but the manifest is available).
+// It may use a remote (= slow) service.
+// If instanceDigest is not nil, it contains a digest of the specific manifest instance to retrieve (when the primary manifest is a manifest list);
+// this never happens if the primary manifest is not a manifest list (e.g. if the source never returns manifest lists).
+// This source implementation does not support manifest lists, so the passed-in instanceDigest should always be nil,
+// as the primary manifest can not be a list, so there can be no secondary instances.
+func (s *Source) GetManifest(ctx context.Context, instanceDigest *digest.Digest) ([]byte, string, error) {
+	if instanceDigest != nil {
+		// How did we even get here? GetManifest(ctx, nil) has returned a manifest.DockerV2Schema2MediaType.
+		return nil, "", errors.New(`Manifest lists are not supported by "docker-daemon:"`)
+	}
+	if s.generatedManifest == nil {
+		if err := s.ensureCachedDataIsPresent(); err != nil {
+			return nil, "", err
+		}
+		m := manifest.Schema2{
+			SchemaVersion: 2,
+			MediaType:     manifest.DockerV2Schema2MediaType,
+			ConfigDescriptor: manifest.Schema2Descriptor{
+				MediaType: manifest.DockerV2Schema2ConfigMediaType,
+				Size:      int64(len(s.configBytes)),
+				Digest:    s.configDigest,
+			},
+			LayersDescriptors: []manifest.Schema2Descriptor{},
+		}
+		for _, diffID := range s.orderedDiffIDList {
+			li, ok := s.knownLayers[diffID]
+			if !ok {
+				return nil, "", errors.Errorf("Internal inconsistency: Information about layer %s missing", diffID)
+			}
+			m.LayersDescriptors = append(m.LayersDescriptors, manifest.Schema2Descriptor{
+				Digest:    diffID, // diffID is a digest of the uncompressed tarball
+				MediaType: manifest.DockerV2Schema2LayerMediaType,
+				Size:      li.size,
+			})
+		}
+		manifestBytes, err := json.Marshal(&m)
+		if err != nil {
+			return nil, "", err
+		}
+		s.generatedManifest = manifestBytes
+	}
+	return s.generatedManifest, manifest.DockerV2Schema2MediaType, nil
+}
+
+// uncompressedReadCloser is an io.ReadCloser that closes both the uncompressed stream and the underlying input.
+type uncompressedReadCloser struct {
+	io.Reader
+	underlyingCloser   func() error
+	uncompressedCloser func() error
+}
+
+func (r uncompressedReadCloser) Close() error {
+	var res error
+	if err := r.uncompressedCloser(); err != nil {
+		res = err
+	}
+	if err := r.underlyingCloser(); err != nil && res == nil {
+		res = err
+	}
+	return res
+}
+
+// HasThreadSafeGetBlob indicates whether GetBlob can be executed concurrently.
+func (s *Source) HasThreadSafeGetBlob() bool {
+	return true
+}
+
+// GetBlob returns a stream for the specified blob, and the blob’s size (or -1 if unknown).
+// The Digest field in BlobInfo is guaranteed to be provided, Size may be -1 and MediaType may be optionally provided.
+// May update BlobInfoCache, preferably after it knows for certain that a blob truly exists at a specific location.
+func (s *Source) GetBlob(ctx context.Context, info types.BlobInfo, cache types.BlobInfoCache) (io.ReadCloser, int64, error) {
+	if err := s.ensureCachedDataIsPresent(); err != nil {
+		return nil, 0, err
+	}
+
+	if info.Digest == s.configDigest { // FIXME? Implement a more general algorithm matching instead of assuming sha256.
+		return ioutil.NopCloser(bytes.NewReader(s.configBytes)), int64(len(s.configBytes)), nil
+	}
+
+	if li, ok := s.knownLayers[info.Digest]; ok { // diffID is a digest of the uncompressed tarball,
+		underlyingStream, err := s.openTarComponent(li.path)
+		if err != nil {
+			return nil, 0, err
+		}
+		closeUnderlyingStream := true
+		defer func() {
+			if closeUnderlyingStream {
+				underlyingStream.Close()
+			}
+		}()
+
+		// In order to handle the fact that digests != diffIDs (and thus that a
+		// caller which is trying to verify the blob will run into problems),
+		// we need to decompress blobs. This is a bit ugly, but it's a
+		// consequence of making everything addressable by their DiffID rather
+		// than by their digest...
+		//
+		// In particular, because the v2s2 manifest being generated uses
+		// DiffIDs, any caller of GetBlob is going to be asking for DiffIDs of
+		// layers not their _actual_ digest. The result is that copy/... will
+		// be verifing a "digest" which is not the actual layer's digest (but
+		// is instead the DiffID).
+
+		uncompressedStream, _, err := compression.AutoDecompress(underlyingStream)
+		if err != nil {
+			return nil, 0, errors.Wrapf(err, "Error auto-decompressing blob %s", info.Digest)
+		}
+
+		newStream := uncompressedReadCloser{
+			Reader:             uncompressedStream,
+			underlyingCloser:   underlyingStream.Close,
+			uncompressedCloser: uncompressedStream.Close,
+		}
+		closeUnderlyingStream = false
+
+		return newStream, li.size, nil
+	}
+
+	return nil, 0, errors.Errorf("Unknown blob %s", info.Digest)
+}
+
+// GetSignatures returns the image's signatures.  It may use a remote (= slow) service.
+// This source implementation does not support manifest lists, so the passed-in instanceDigest should always be nil,
+// as there can be no secondary manifests.
+func (s *Source) GetSignatures(ctx context.Context, instanceDigest *digest.Digest) ([][]byte, error) {
+	if instanceDigest != nil {
+		// How did we even get here? GetManifest(ctx, nil) has returned a manifest.DockerV2Schema2MediaType.
+		return nil, errors.Errorf(`Manifest lists are not supported by "docker-daemon:"`)
+	}
+	return [][]byte{}, nil
+}
+
+// LayerInfosForCopy returns either nil (meaning the values in the manifest are fine), or updated values for the layer
+// blobsums that are listed in the image's manifest.  If values are returned, they should be used when using GetBlob()
+// to read the image's layers.
+// This source implementation does not support manifest lists, so the passed-in instanceDigest should always be nil,
+// as the primary manifest can not be a list, so there can be no secondary manifests.
+// The Digest field is guaranteed to be provided; Size may be -1.
+// WARNING: The list may contain duplicates, and they are semantically relevant.
+func (s *Source) LayerInfosForCopy(context.Context, *digest.Digest) ([]types.BlobInfo, error) {
+	return nil, nil
+}

vendor/github.com/containers/image/v5/docker/tarfile/types.go

@@ -0,0 +1,28 @@
+package tarfile
+
+import (
+	"github.com/containers/image/v5/manifest"
+	"github.com/opencontainers/go-digest"
+)
+
+// Various data structures.
+
+// Based on github.com/docker/docker/image/tarexport/tarexport.go
+const (
+	manifestFileName           = "manifest.json"
+	legacyLayerFileName        = "layer.tar"
+	legacyConfigFileName       = "json"
+	legacyVersionFileName      = "VERSION"
+	legacyRepositoriesFileName = "repositories"
+)
+
+// ManifestItem is an element of the array stored in the top-level manifest.json file.
+type ManifestItem struct {
+	Config       string
+	RepoTags     []string
+	Layers       []string
+	Parent       imageID                                      `json:",omitempty"`
+	LayerSources map[digest.Digest]manifest.Schema2Descriptor `json:",omitempty"`
+}
+
+type imageID string