manifest: slight cleanup of init / registration

Change the marshal-funcs to a regular function instead of definining
as part of an init and remove some intermediate variables.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

manifest/manifestlist/manifestlist.go

@@ -24,27 +24,26 @@ var SchemaVersion = manifest.Versioned{
 }
 
 func init() {
-	manifestListFunc := func(b []byte) (distribution.Manifest, distribution.Descriptor, error) {
+	if err := distribution.RegisterManifestSchema(MediaTypeManifestList, unmarshalManifestList); err != nil {
-		m := new(DeserializedManifestList)
+		panic(fmt.Sprintf("Unable to register manifest: %s", err))
-		err := m.UnmarshalJSON(b)
+	}
-		if err != nil {
+}
+
+func unmarshalManifestList(b []byte) (distribution.Manifest, distribution.Descriptor, error) {
+	m := &DeserializedManifestList{}
+	if err := m.UnmarshalJSON(b); err != nil {
 		return nil, distribution.Descriptor{}, err
 	}
 
 	if m.MediaType != MediaTypeManifestList {
-			err = fmt.Errorf("mediaType in manifest list should be '%s' not '%s'",
+		return nil, distribution.Descriptor{}, fmt.Errorf("mediaType in manifest list should be '%s' not '%s'", MediaTypeManifestList, m.MediaType)
-				MediaTypeManifestList, m.MediaType)
-
-			return nil, distribution.Descriptor{}, err
 	}
 
-		dgst := digest.FromBytes(b)
+	return m, distribution.Descriptor{
-		return m, distribution.Descriptor{Digest: dgst, Size: int64(len(b)), MediaType: MediaTypeManifestList}, err
+		Digest:    digest.FromBytes(b),
-	}
+		Size:      int64(len(b)),
-	err := distribution.RegisterManifestSchema(MediaTypeManifestList, manifestListFunc)
+		MediaType: MediaTypeManifestList,
-	if err != nil {
+	}, nil
-		panic(fmt.Sprintf("Unable to register manifest: %s", err))
-	}
 }
 
 // PlatformSpec specifies a platform where a particular image manifest is

manifest/ocischema/index.go

@@ -19,35 +19,31 @@ var IndexSchemaVersion = manifest.Versioned{
 }
 
 func init() {
-	imageIndexFunc := func(b []byte) (distribution.Manifest, distribution.Descriptor, error) {
+	if err := distribution.RegisterManifestSchema(v1.MediaTypeImageIndex, unmarshalImageIndex); err != nil {
+		panic(fmt.Sprintf("Unable to register OCI Image Index: %s", err))
+	}
+}
+
+func unmarshalImageIndex(b []byte) (distribution.Manifest, distribution.Descriptor, error) {
 	if err := validateIndex(b); err != nil {
 		return nil, distribution.Descriptor{}, err
 	}
-		m := new(DeserializedImageIndex)
+
-		err := m.UnmarshalJSON(b)
+	m := &DeserializedImageIndex{}
-		if err != nil {
+	if err := m.UnmarshalJSON(b); err != nil {
 		return nil, distribution.Descriptor{}, err
 	}
 
 	if m.MediaType != "" && m.MediaType != v1.MediaTypeImageIndex {
-			err = fmt.Errorf("if present, mediaType in image index should be '%s' not '%s'",
+		return nil, distribution.Descriptor{}, fmt.Errorf("if present, mediaType in image index should be '%s' not '%s'", v1.MediaTypeImageIndex, m.MediaType)
-				v1.MediaTypeImageIndex, m.MediaType)
-
-			return nil, distribution.Descriptor{}, err
 	}
 
-		dgst := digest.FromBytes(b)
 	return m, distribution.Descriptor{
 		MediaType:   v1.MediaTypeImageIndex,
-			Digest:      dgst,
+		Digest:      digest.FromBytes(b),
 		Size:        int64(len(b)),
 		Annotations: m.Annotations,
-		}, err
+	}, nil
-	}
-	err := distribution.RegisterManifestSchema(v1.MediaTypeImageIndex, imageIndexFunc)
-	if err != nil {
-		panic(fmt.Sprintf("Unable to register OCI Image Index: %s", err))
-	}
 }
 
 // ImageIndex references manifests for various platforms.

manifest/ocischema/manifest.go

@@ -19,28 +19,27 @@ var SchemaVersion = manifest.Versioned{
 }
 
 func init() {
-	ocischemaFunc := func(b []byte) (distribution.Manifest, distribution.Descriptor, error) {
+	if err := distribution.RegisterManifestSchema(v1.MediaTypeImageManifest, unmarshalOCISchema); err != nil {
+		panic(fmt.Sprintf("Unable to register manifest: %s", err))
+	}
+}
+
+func unmarshalOCISchema(b []byte) (distribution.Manifest, distribution.Descriptor, error) {
 	if err := validateManifest(b); err != nil {
 		return nil, distribution.Descriptor{}, err
 	}
-		m := new(DeserializedManifest)
+
-		err := m.UnmarshalJSON(b)
+	m := &DeserializedManifest{}
-		if err != nil {
+	if err := m.UnmarshalJSON(b); err != nil {
 		return nil, distribution.Descriptor{}, err
 	}
 
-		dgst := digest.FromBytes(b)
 	return m, distribution.Descriptor{
 		MediaType:   v1.MediaTypeImageManifest,
-			Digest:      dgst,
+		Digest:      digest.FromBytes(b),
 		Size:        int64(len(b)),
 		Annotations: m.Annotations,
-		}, err
+	}, nil
-	}
-	err := distribution.RegisterManifestSchema(v1.MediaTypeImageManifest, ocischemaFunc)
-	if err != nil {
-		panic(fmt.Sprintf("Unable to register manifest: %s", err))
-	}
 }
 
 // Manifest defines a ocischema manifest.

manifest/schema2/manifest.go

@@ -41,20 +41,22 @@ var SchemaVersion = manifest.Versioned{
 }
 
 func init() {
-	schema2Func := func(b []byte) (distribution.Manifest, distribution.Descriptor, error) {
+	if err := distribution.RegisterManifestSchema(MediaTypeManifest, unmarshalSchema2); err != nil {
-		m := new(DeserializedManifest)
+		panic(fmt.Sprintf("Unable to register manifest: %s", err))
-		err := m.UnmarshalJSON(b)
+	}
-		if err != nil {
+}
+
+func unmarshalSchema2(b []byte) (distribution.Manifest, distribution.Descriptor, error) {
+	m := &DeserializedManifest{}
+	if err := m.UnmarshalJSON(b); err != nil {
 		return nil, distribution.Descriptor{}, err
 	}
 
-		dgst := digest.FromBytes(b)
+	return m, distribution.Descriptor{
-		return m, distribution.Descriptor{Digest: dgst, Size: int64(len(b)), MediaType: MediaTypeManifest}, err
+		Digest:    digest.FromBytes(b),
-	}
+		Size:      int64(len(b)),
-	err := distribution.RegisterManifestSchema(MediaTypeManifest, schema2Func)
+		MediaType: MediaTypeManifest,
-	if err != nil {
+	}, nil
-		panic(fmt.Sprintf("Unable to register manifest: %s", err))
-	}
 }
 
 // Manifest defines a schema2 manifest.