fix: removes the NoSuchTagSet error in GetObjecTagging

Fixes #1686

GetObjectTagging previously returned a `NoSuchTagSet` error when no object tags were set. This has been fixed, and an empty tag set is now returned instead.

backend/posix/posix.go

@@ -3785,10 +3785,10 @@ func (p *Posix) GetObject(_ context.Context, input *s3.GetObjectInput) (*s3.GetO
 
 		var tagCount *int32
 		tags, err := p.getAttrTags(bucket, object, versionId)
-		if err != nil && !errors.Is(err, s3err.GetAPIError(s3err.ErrBucketTaggingNotFound)) {
+		if err != nil {
 			return nil, err
 		}
-		if tags != nil {
+		if len(tags) != 0 {
 			tgCount := int32(len(tags))
 			tagCount = &tgCount
 		}
@@ -3865,10 +3865,10 @@ func (p *Posix) GetObject(_ context.Context, input *s3.GetObjectInput) (*s3.GetO
 
 	var tagCount *int32
 	tags, err := p.getAttrTags(bucket, object, versionId)
-	if err != nil && !errors.Is(err, s3err.GetAPIError(s3err.ErrBucketTaggingNotFound)) {
+	if err != nil {
 		return nil, err
 	}
-	if tags != nil {
+	if len(tags) != 0 {
 		tgCount := int32(len(tags))
 		tagCount = &tgCount
 	}
@@ -4090,10 +4090,10 @@ func (p *Posix) HeadObject(ctx context.Context, input *s3.HeadObjectInput) (*s3.
 
 	var tagCount *int32
 	tags, err := p.getAttrTags(bucket, object, versionId)
-	if err != nil && !errors.Is(err, s3err.GetAPIError(s3err.ErrBucketTaggingNotFound)) {
+	if err != nil {
 		return nil, err
 	}
-	if tags != nil {
+	if len(tags) != 0 {
 		tc := int32(len(tags))
 		tagCount = &tc
 	}
@@ -4874,6 +4874,10 @@ func (p *Posix) getAttrTags(bucket, object, versionId string) (map[string]string
 		return nil, s3err.GetAPIError(s3err.ErrNoSuchKey)
 	}
 	if errors.Is(err, meta.ErrNoSuchKey) {
+		if object != "" {
+			// return empty tag set for object tagging
+			return tags, nil
+		}
 		return nil, s3err.GetAPIError(s3err.ErrBucketTaggingNotFound)
 	}
 	if err != nil {

tests/integration/GetObjectTagging.go

@@ -48,14 +48,19 @@ func GetObjectTagging_unset_tags(s *S3Conf) error {
 			return err
 		}
 		ctx, cancel := context.WithTimeout(context.Background(), shortTimeout)
-		_, err = s3client.GetObjectTagging(ctx, &s3.GetObjectTaggingInput{
+		res, err := s3client.GetObjectTagging(ctx, &s3.GetObjectTaggingInput{
 			Bucket: &bucket,
 			Key:    &obj,
 		})
 		cancel()
-		if err := checkApiErr(err, s3err.GetAPIError(s3err.ErrBucketTaggingNotFound)); err != nil {
+		if err != nil {
 			return err
 		}
+
+		if len(res.TagSet) != 0 {
+			return fmt.Errorf("expected empty tag set, instead got %v", res.TagSet)
+		}
+
 		return nil
 	})
 }

tests/integration/group-tests.go

@@ -778,6 +778,7 @@ func TestFullFlow(ts *TestState) {
 	TestDeleteObjects(ts)
 	TestCopyObject(ts)
 	TestPutObjectTagging(ts)
+	TestGetObjectTagging(ts)
 	TestDeleteObjectTagging(ts)
 	TestCreateMultipartUpload(ts)
 	TestUploadPart(ts)

tests/integration/versioning.go

@@ -3400,12 +3400,20 @@ func Versioning_PutGetDeleteObjectTagging_success(s *S3Conf) error {
 		}
 
 		ctx, cancel = context.WithTimeout(context.Background(), shortTimeout)
-		_, err = s3client.GetObjectTagging(ctx, &s3.GetObjectTaggingInput{
+		r, err := s3client.GetObjectTagging(ctx, &s3.GetObjectTaggingInput{
 			Bucket:    &bucket,
 			Key:       &obj,
 			VersionId: versionId,
 		})
 		cancel()
-		return checkApiErr(err, s3err.GetAPIError(s3err.ErrBucketTaggingNotFound))
+		if err != nil {
+			return err
+		}
+
+		if len(r.TagSet) != 0 {
+			return fmt.Errorf("expected empty tag set, instead got %v", r.TagSet)
+		}
+
+		return nil
 	}, withVersioning(types.BucketVersioningStatusEnabled))
 }