Platforms: Add From/ToProto helpers for types

Helpers to convert from a slice of platforms to our protobuf representation
and vice-versa appear a couple times. It seems sane to just expose this facility
in the platforms pkg.

Signed-off-by: Danny Canter <danny@dcantah.dev>

pkg/transfer/archive/exporter.go

@@ -156,15 +156,7 @@ func (iis *ImageExportStream) UnmarshalAny(ctx context.Context, sm streaming.Str
 		return err
 	}
 
-	var specified []v1.Platform
-	for _, p := range s.Platforms {
-		specified = append(specified, v1.Platform{
-			OS:           p.OS,
-			Architecture: p.Architecture,
-			Variant:      p.Variant,
-		})
-	}
-
+	specified := platforms.FromProto(s.Platforms)
 	iis.stream = tstreaming.WriteByteStream(ctx, stream)
 	iis.mediaType = s.MediaType
 	iis.platforms = specified

pkg/transfer/image/imagestore.go

@@ -363,7 +363,7 @@ func (is *Store) MarshalAny(context.Context, streaming.StreamCreator) (typeurl.A
 		Labels:          is.imageLabels,
 		ManifestLimit:   uint32(is.manifestLimit),
 		AllMetadata:     is.allMetadata,
-		Platforms:       platformsToProto(is.platforms),
+		Platforms:       platforms.ToProto(is.platforms),
 		ExtraReferences: referencesToProto(is.extraReferences),
 		Unpacks:         unpackToProto(is.unpacks),
 	}
@@ -380,37 +380,13 @@ func (is *Store) UnmarshalAny(ctx context.Context, sm streaming.StreamGetter, a
 	is.imageLabels = s.Labels
 	is.manifestLimit = int(s.ManifestLimit)
 	is.allMetadata = s.AllMetadata
-	is.platforms = platformFromProto(s.Platforms)
+	is.platforms = platforms.FromProto(s.Platforms)
 	is.extraReferences = referencesFromProto(s.ExtraReferences)
 	is.unpacks = unpackFromProto(s.Unpacks)
 
 	return nil
 }
 
-func platformsToProto(platforms []ocispec.Platform) []*types.Platform {
-	ap := make([]*types.Platform, len(platforms))
-	for i := range platforms {
-		p := types.Platform{
-			OS:           platforms[i].OS,
-			Architecture: platforms[i].Architecture,
-			Variant:      platforms[i].Variant,
-		}
-
-		ap[i] = &p
-	}
-	return ap
-}
-
-func platformFromProto(platforms []*types.Platform) []ocispec.Platform {
-	op := make([]ocispec.Platform, len(platforms))
-	for i := range platforms {
-		op[i].OS = platforms[i].OS
-		op[i].Architecture = platforms[i].Architecture
-		op[i].Variant = platforms[i].Variant
-	}
-	return op
-}
-
 func referencesToProto(references []Reference) []*transfertypes.ImageReference {
 	ir := make([]*transfertypes.ImageReference, len(references))
 	for i := range references {

platforms/platforms.go

@@ -116,6 +116,7 @@ import (
 
 	specs "github.com/opencontainers/image-spec/specs-go/v1"
 
+	"github.com/containerd/containerd/api/types"
 	"github.com/containerd/containerd/errdefs"
 )
 
@@ -262,3 +263,30 @@ func Normalize(platform specs.Platform) specs.Platform {
 
 	return platform
 }
+
+// ToProto converts from a slice of [Platform] to a slice of
+// the protobuf definition [types.Platform].
+func ToProto(platforms []Platform) []*types.Platform {
+	ap := make([]*types.Platform, len(platforms))
+	for i := range platforms {
+		p := types.Platform{
+			OS:           platforms[i].OS,
+			Architecture: platforms[i].Architecture,
+			Variant:      platforms[i].Variant,
+		}
+		ap[i] = &p
+	}
+	return ap
+}
+
+// FromProto converts a slice of the protobuf definition [types.Platform]
+// to a slice of [Platform].
+func FromProto(platforms []*types.Platform) []Platform {
+	op := make([]Platform, len(platforms))
+	for i := range platforms {
+		op[i].OS = platforms[i].OS
+		op[i].Architecture = platforms[i].Architecture
+		op[i].Variant = platforms[i].Variant
+	}
+	return op
+}

services/introspection/local.go

@@ -24,9 +24,9 @@ import (
 	"sync"
 
 	api "github.com/containerd/containerd/api/services/introspection/v1"
-	"github.com/containerd/containerd/api/types"
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/filters"
+	"github.com/containerd/containerd/platforms"
 	"github.com/containerd/containerd/plugin"
 	ptypes "github.com/containerd/containerd/protobuf/types"
 	"github.com/containerd/containerd/services"
@@ -189,15 +189,6 @@ func adaptPlugin(o interface{}) filters.Adaptor {
 func pluginsToPB(plugins []*plugin.Plugin) []*api.Plugin {
 	var pluginsPB []*api.Plugin
 	for _, p := range plugins {
-		var platforms []*types.Platform
-		for _, p := range p.Meta.Platforms {
-			platforms = append(platforms, &types.Platform{
-				OS:           p.OS,
-				Architecture: p.Architecture,
-				Variant:      p.Variant,
-			})
-		}
-
 		var requires []string
 		for _, r := range p.Registration.Requires {
 			requires = append(requires, r.String())
@@ -231,7 +222,7 @@ func pluginsToPB(plugins []*plugin.Plugin) []*api.Plugin {
 			Type:         p.Registration.Type.String(),
 			ID:           p.Registration.ID,
 			Requires:     requires,
-			Platforms:    platforms,
+			Platforms:    platforms.ToProto(p.Meta.Platforms),
 			Capabilities: p.Meta.Capabilities,
 			Exports:      p.Meta.Exports,
 			InitErr:      initErr,