Move diff to core/diff

Signed-off-by: Derek McGowan <derek@mcg.dev>

core/diff/proxy/differ.go

@@ -0,0 +1,100 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package proxy
+
+import (
+	"context"
+
+	diffapi "github.com/containerd/containerd/v2/api/services/diff/v1"
+	"github.com/containerd/containerd/v2/core/diff"
+	"github.com/containerd/containerd/v2/errdefs"
+	"github.com/containerd/containerd/v2/mount"
+	"github.com/containerd/containerd/v2/oci"
+	"github.com/containerd/containerd/v2/pkg/epoch"
+	"github.com/containerd/containerd/v2/protobuf"
+	ptypes "github.com/containerd/containerd/v2/protobuf/types"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+
+	"google.golang.org/protobuf/types/known/timestamppb"
+)
+
+// NewDiffApplier returns a new comparer and applier which communicates
+// over a GRPC connection.
+func NewDiffApplier(client diffapi.DiffClient) interface{} {
+	return &diffRemote{
+		client: client,
+	}
+}
+
+type diffRemote struct {
+	client diffapi.DiffClient
+}
+
+func (r *diffRemote) Apply(ctx context.Context, desc ocispec.Descriptor, mounts []mount.Mount, opts ...diff.ApplyOpt) (ocispec.Descriptor, error) {
+	var config diff.ApplyConfig
+	for _, opt := range opts {
+		if err := opt(ctx, desc, &config); err != nil {
+			return ocispec.Descriptor{}, err
+		}
+	}
+
+	payloads := make(map[string]*ptypes.Any)
+	for k, v := range config.ProcessorPayloads {
+		payloads[k] = protobuf.FromAny(v)
+	}
+
+	req := &diffapi.ApplyRequest{
+		Diff:     oci.DescriptorToProto(desc),
+		Mounts:   mount.ToProto(mounts),
+		Payloads: payloads,
+		SyncFs:   config.SyncFs,
+	}
+	resp, err := r.client.Apply(ctx, req)
+	if err != nil {
+		return ocispec.Descriptor{}, errdefs.FromGRPC(err)
+	}
+	return oci.DescriptorFromProto(resp.Applied), nil
+}
+
+func (r *diffRemote) Compare(ctx context.Context, a, b []mount.Mount, opts ...diff.Opt) (ocispec.Descriptor, error) {
+	var config diff.Config
+	for _, opt := range opts {
+		if err := opt(&config); err != nil {
+			return ocispec.Descriptor{}, err
+		}
+	}
+	if tm := epoch.FromContext(ctx); tm != nil && config.SourceDateEpoch == nil {
+		config.SourceDateEpoch = tm
+	}
+	var sourceDateEpoch *timestamppb.Timestamp
+	if config.SourceDateEpoch != nil {
+		sourceDateEpoch = timestamppb.New(*config.SourceDateEpoch)
+	}
+	req := &diffapi.DiffRequest{
+		Left:            mount.ToProto(a),
+		Right:           mount.ToProto(b),
+		MediaType:       config.MediaType,
+		Ref:             config.Reference,
+		Labels:          config.Labels,
+		SourceDateEpoch: sourceDateEpoch,
+	}
+	resp, err := r.client.Diff(ctx, req)
+	if err != nil {
+		return ocispec.Descriptor{}, errdefs.FromGRPC(err)
+	}
+	return oci.DescriptorFromProto(resp.Diff), nil
+}