Move manifest package to schema1

As we begin our march towards multi-arch, we must prepare for the reality of
multiple manifest schemas. This is the beginning of a set of changes to
facilitate this. We are both moving this package into its target position where
it may live peacefully next to other manfiest versions.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

manifest/schema1/manifest.go

@@ -0,0 +1,125 @@
+package schema1
+
+import (
+	"encoding/json"
+
+	"github.com/docker/distribution/digest"
+	"github.com/docker/distribution/manifest"
+	"github.com/docker/libtrust"
+)
+
+// TODO(stevvooe): When we rev the manifest format, the contents of this
+// package should be moved to manifest/v1.
+
+const (
+	// ManifestMediaType specifies the mediaType for the current version. Note
+	// that for schema version 1, the the media is optionally
+	// "application/json".
+	ManifestMediaType = "application/vnd.docker.distribution.manifest.v1+json"
+)
+
+var (
+	// SchemaVersion provides a pre-initialized version structure for this
+	// packages version of the manifest.
+	SchemaVersion = manifest.Versioned{
+		SchemaVersion: 1,
+	}
+)
+
+// Manifest provides the base accessible fields for working with V2 image
+// format in the registry.
+type Manifest struct {
+	manifest.Versioned
+
+	// Name is the name of the image's repository
+	Name string `json:"name"`
+
+	// Tag is the tag of the image specified by this manifest
+	Tag string `json:"tag"`
+
+	// Architecture is the host architecture on which this image is intended to
+	// run
+	Architecture string `json:"architecture"`
+
+	// FSLayers is a list of filesystem layer blobSums contained in this image
+	FSLayers []FSLayer `json:"fsLayers"`
+
+	// History is a list of unstructured historical data for v1 compatibility
+	History []History `json:"history"`
+}
+
+// SignedManifest provides an envelope for a signed image manifest, including
+// the format sensitive raw bytes. It contains fields to
+type SignedManifest struct {
+	Manifest
+
+	// Raw is the byte representation of the ImageManifest, used for signature
+	// verification. The value of Raw must be used directly during
+	// serialization, or the signature check will fail. The manifest byte
+	// representation cannot change or it will have to be re-signed.
+	Raw []byte `json:"-"`
+}
+
+// UnmarshalJSON populates a new ImageManifest struct from JSON data.
+func (sm *SignedManifest) UnmarshalJSON(b []byte) error {
+	var manifest Manifest
+	if err := json.Unmarshal(b, &manifest); err != nil {
+		return err
+	}
+
+	sm.Manifest = manifest
+	sm.Raw = make([]byte, len(b), len(b))
+	copy(sm.Raw, b)
+
+	return nil
+}
+
+// Payload returns the raw, signed content of the signed manifest. The
+// contents can be used to calculate the content identifier.
+func (sm *SignedManifest) Payload() ([]byte, error) {
+	jsig, err := libtrust.ParsePrettySignature(sm.Raw, "signatures")
+	if err != nil {
+		return nil, err
+	}
+
+	// Resolve the payload in the manifest.
+	return jsig.Payload()
+}
+
+// Signatures returns the signatures as provided by
+// (*libtrust.JSONSignature).Signatures. The byte slices are opaque jws
+// signatures.
+func (sm *SignedManifest) Signatures() ([][]byte, error) {
+	jsig, err := libtrust.ParsePrettySignature(sm.Raw, "signatures")
+	if err != nil {
+		return nil, err
+	}
+
+	// Resolve the payload in the manifest.
+	return jsig.Signatures()
+}
+
+// MarshalJSON returns the contents of raw. If Raw is nil, marshals the inner
+// contents. Applications requiring a marshaled signed manifest should simply
+// use Raw directly, since the the content produced by json.Marshal will be
+// compacted and will fail signature checks.
+func (sm *SignedManifest) MarshalJSON() ([]byte, error) {
+	if len(sm.Raw) > 0 {
+		return sm.Raw, nil
+	}
+
+	// If the raw data is not available, just dump the inner content.
+	return json.Marshal(&sm.Manifest)
+}
+
+// FSLayer is a container struct for BlobSums defined in an image manifest
+type FSLayer struct {
+	// BlobSum is the tarsum of the referenced filesystem image layer
+	BlobSum digest.Digest `json:"blobSum"`
+}
+
+// History stores unstructured v1 compatibility information
+type History struct {
+	// V1Compatibility is the raw v1 compatibility information
+	V1Compatibility string `json:"v1Compatibility"`
+}