cleanup object-lock/bucket tagging for gateways (#9548)

This PR is to ensure that we call the relevant object
layer APIs for necessary S3 API level functionalities
allowing gateway implementations to return proper
errors as NotImplemented{}

This allows for all our tests in mint to behave
appropriately and can be handled appropriately as
well.

cmd/bucket-tagging.go

@@ -0,0 +1,61 @@
+/*
+ * MinIO Cloud Storage, (C) 2020 MinIO, Inc.
+ *
+ * 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 cmd
+
+import (
+	"context"
+	"encoding/xml"
+	"path"
+
+	"github.com/minio/minio-go/v6/pkg/tags"
+)
+
+func saveBucketTagging(ctx context.Context, objAPI ObjectLayer, bucket string, t *tags.Tags) error {
+	data, err := xml.Marshal(t)
+	if err != nil {
+		return toObjectErr(err, bucket)
+	}
+	configFile := path.Join(bucketConfigPrefix, bucket, bucketTaggingConfigFile)
+	if err := saveConfig(ctx, objAPI, configFile, data); err != nil {
+		return toObjectErr(err, bucket)
+	}
+	return nil
+}
+
+func deleteBucketTagging(ctx context.Context, objAPI ObjectLayer, bucket string) error {
+	configFile := path.Join(bucketConfigPrefix, bucket, bucketTaggingConfigFile)
+	if err := deleteConfig(ctx, objAPI, configFile); err != nil && err != errConfigNotFound {
+		return toObjectErr(err, bucket)
+	}
+	return nil
+}
+
+func readBucketTagging(ctx context.Context, objAPI ObjectLayer, bucket string) (*tags.Tags, error) {
+	configFile := path.Join(bucketConfigPrefix, bucket, bucketTaggingConfigFile)
+	configData, err := readConfig(ctx, objAPI, configFile)
+	if err != nil {
+		if err == errConfigNotFound {
+			return nil, BucketTaggingNotFound{Bucket: bucket}
+		}
+		return nil, toObjectErr(err, bucket)
+	}
+	t := &tags.Tags{}
+	if err = xml.Unmarshal(configData, t); err != nil {
+		return nil, toObjectErr(err, bucket)
+	}
+	return t, nil
+}