mount: Add From/ToProto helpers

Helpers to convert from containerd's [Mount] to its protobuf structure for
[Mount] and vice-versa appear three times. It seems sane to just expose
this facility in /mount.

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

contrib/diffservice/service.go

@@ -50,7 +50,7 @@ func (s *service) Apply(ctx context.Context, er *diffapi.ApplyRequest) (*diffapi
 		ocidesc ocispec.Descriptor
 		err     error
 		desc    = toDescriptor(er.Diff)
-		mounts  = toMounts(er.Mounts)
+		mounts  = mount.FromProto(er.Mounts)
 	)
 
 	var opts []diff.ApplyOpt
@@ -79,8 +79,8 @@ func (s *service) Diff(ctx context.Context, dr *diffapi.DiffRequest) (*diffapi.D
 	var (
 		ocidesc ocispec.Descriptor
 		err     error
-		aMounts = toMounts(dr.Left)
-		bMounts = toMounts(dr.Right)
+		aMounts = mount.FromProto(dr.Left)
+		bMounts = mount.FromProto(dr.Right)
 	)
 
 	var opts []diff.Opt
@@ -108,19 +108,6 @@ func (s *service) Diff(ctx context.Context, dr *diffapi.DiffRequest) (*diffapi.D
 	}, nil
 }
 
-func toMounts(apim []*types.Mount) []mount.Mount {
-	mounts := make([]mount.Mount, len(apim))
-	for i, m := range apim {
-		mounts[i] = mount.Mount{
-			Type:    m.Type,
-			Source:  m.Source,
-			Target:  m.Target,
-			Options: m.Options,
-		}
-	}
-	return mounts
-}
-
 func toDescriptor(d *types.Descriptor) ocispec.Descriptor {
 	return ocispec.Descriptor{
 		MediaType:   d.MediaType,

contrib/snapshotservice/service.go

@@ -20,7 +20,6 @@ import (
 	"context"
 
 	snapshotsapi "github.com/containerd/containerd/api/services/snapshots/v1"
-	"github.com/containerd/containerd/api/types"
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/mount"
 	"github.com/containerd/containerd/protobuf"
@@ -51,7 +50,7 @@ func (s service) Prepare(ctx context.Context, pr *snapshotsapi.PrepareSnapshotRe
 	}
 
 	return &snapshotsapi.PrepareSnapshotResponse{
-		Mounts: fromMounts(mounts),
+		Mounts: mount.ToProto(mounts),
 	}, nil
 }
 
@@ -65,7 +64,7 @@ func (s service) View(ctx context.Context, pr *snapshotsapi.ViewSnapshotRequest)
 		return nil, errdefs.ToGRPC(err)
 	}
 	return &snapshotsapi.ViewSnapshotResponse{
-		Mounts: fromMounts(mounts),
+		Mounts: mount.ToProto(mounts),
 	}, nil
 }
 
@@ -75,7 +74,7 @@ func (s service) Mounts(ctx context.Context, mr *snapshotsapi.MountsRequest) (*s
 		return nil, errdefs.ToGRPC(err)
 	}
 	return &snapshotsapi.MountsResponse{
-		Mounts: fromMounts(mounts),
+		Mounts: mount.ToProto(mounts),
 	}, nil
 }
 
@@ -199,19 +198,6 @@ func fromInfo(info snapshots.Info) *snapshotsapi.Info {
 	}
 }
 
-func fromMounts(mounts []mount.Mount) []*types.Mount {
-	out := make([]*types.Mount, len(mounts))
-	for i, m := range mounts {
-		out[i] = &types.Mount{
-			Type:    m.Type,
-			Source:  m.Source,
-			Target:  m.Target,
-			Options: m.Options,
-		}
-	}
-	return out
-}
-
 func toInfo(info *snapshotsapi.Info) snapshots.Info {
 	return snapshots.Info{
 		Name:    info.Name,