fix: copy-object with replace metadata-directive

In copy-object, if the source and destination are the same then
X-Amz-Metadata-Directive must be set to "REPLACE" in order to use
this api call to update the metadata of the object in place.

The default X-Amz-Metadata-Directive is "COPY" if not specified.
"COPY" is only valid if source and destination are not the same
object.

When "REPLACE" selected, metadata does not have to differ for the
call to be successful. The "REPLACE" always sets the incoming
metadata (even if empty or the same as the source).

Fixes #734

backend/posix/posix.go

@@ -805,20 +805,6 @@ func (p *Posix) loadUserMetaData(bucket, object string, m map[string]string) (st
 	return contentType, contentEncoding
 }
 
-func compareUserMetadata(meta1, meta2 map[string]string) bool {
-	if len(meta1) != len(meta2) {
-		return false
-	}
-
-	for key, val := range meta1 {
-		if meta2[key] != val {
-			return false
-		}
-	}
-
-	return true
-}
-
 func isValidMeta(val string) bool {
 	if strings.HasPrefix(val, metaHdr) {
 		return true
@@ -2012,42 +1998,47 @@ func (p *Posix) CopyObject(ctx context.Context, input *s3.CopyObjectInput) (*s3.
 		return nil, s3err.GetAPIError(s3err.ErrNoSuchKey)
 	}
 
-	meta := make(map[string]string)
-	p.loadUserMetaData(srcBucket, srcObject, meta)
+	mdmap := make(map[string]string)
+	p.loadUserMetaData(srcBucket, srcObject, mdmap)
+
+	var etag string
 
 	dstObjdPath := filepath.Join(dstBucket, dstObject)
 	if dstObjdPath == objPath {
-		if compareUserMetadata(meta, input.Metadata) {
+		if input.MetadataDirective == types.MetadataDirectiveCopy {
 			return &s3.CopyObjectOutput{}, s3err.GetAPIError(s3err.ErrInvalidCopyDest)
-		} else {
-			for key := range meta {
-				err := p.meta.DeleteAttribute(dstBucket, dstObject, key)
-				if err != nil {
-					return nil, fmt.Errorf("delete user metadata: %w", err)
-				}
+		}
+
+		for key := range mdmap {
+			err := p.meta.DeleteAttribute(dstBucket, dstObject, key)
+			if err != nil && !errors.Is(err, meta.ErrNoSuchKey) {
+				return nil, fmt.Errorf("delete user metadata: %w", err)
 			}
-			for k, v := range input.Metadata {
-				err := p.meta.StoreAttribute(dstBucket, dstObject,
-					fmt.Sprintf("%v.%v", metaHdr, k), []byte(v))
-				if err != nil {
-					return nil, fmt.Errorf("set user attr %q: %w", k, err)
-				}
+		}
+		for k, v := range input.Metadata {
+			err := p.meta.StoreAttribute(dstBucket, dstObject,
+				fmt.Sprintf("%v.%v", metaHdr, k), []byte(v))
+			if err != nil {
+				return nil, fmt.Errorf("set user attr %q: %w", k, err)
 			}
 		}
-	}
 
-	contentLength := fi.Size()
+		b, _ := p.meta.RetrieveAttribute(dstBucket, dstObject, etagkey)
+		etag = string(b)
+	} else {
+		contentLength := fi.Size()
 
-	etag, err := p.PutObject(ctx,
-		&s3.PutObjectInput{
-			Bucket:        &dstBucket,
-			Key:           &dstObject,
-			Body:          f,
-			ContentLength: &contentLength,
-			Metadata:      meta,
-		})
-	if err != nil {
-		return nil, err
+		etag, err = p.PutObject(ctx,
+			&s3.PutObjectInput{
+				Bucket:        &dstBucket,
+				Key:           &dstObject,
+				Body:          f,
+				ContentLength: &contentLength,
+				Metadata:      input.Metadata,
+			})
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	fi, err = os.Stat(dstObjdPath)

s3api/controllers/base.go

@@ -1533,6 +1533,7 @@ func (c S3ApiController) PutActions(ctx *fiber.Ctx) error {
 	copySrcModifSince := ctx.Get("X-Amz-Copy-Source-If-Modified-Since")
 	copySrcUnmodifSince := ctx.Get("X-Amz-Copy-Source-If-Unmodified-Since")
 	copySrcRange := ctx.Get("X-Amz-Copy-Source-Range")
+	directive := ctx.Get("X-Amz-Metadata-Directive")
 
 	// Permission headers
 	acl := ctx.Get("X-Amz-Acl")
@@ -2054,6 +2055,22 @@ func (c S3ApiController) PutActions(ctx *fiber.Ctx) error {
 
 		metadata := utils.GetUserMetaData(&ctx.Request().Header)
 
+		if directive != "" && directive != "COPY" && directive != "REPLACE" {
+			return SendXMLResponse(ctx, nil,
+				s3err.GetAPIError(s3err.ErrInvalidMetadataDirective),
+				&MetaOpts{
+					Logger:      c.logger,
+					MetricsMng:  c.mm,
+					Action:      metrics.ActionCopyObject,
+					BucketOwner: parsedAcl.Owner,
+				})
+		}
+
+		metaDirective := types.MetadataDirectiveCopy
+		if directive == "REPLACE" {
+			metaDirective = types.MetadataDirectiveReplace
+		}
+
 		res, err := c.be.CopyObject(ctx.Context(),
 			&s3.CopyObjectInput{
 				Bucket:                      &bucket,
@@ -2065,6 +2082,7 @@ func (c S3ApiController) PutActions(ctx *fiber.Ctx) error {
 				CopySourceIfUnmodifiedSince: umtime,
 				ExpectedBucketOwner:         &acct.Access,
 				Metadata:                    metadata,
+				MetadataDirective:           metaDirective,
 				StorageClass:                types.StorageClass(storageClass),
 			})
 		if err == nil {

s3err/s3err.go

@@ -130,6 +130,7 @@ const (
 	ErrMalformedACL
 	ErrUnexpectedContent
 	ErrMissingSecurityHeader
+	ErrInvalidMetadataDirective
 
 	// Non-AWS errors
 	ErrExistingObjectIsDirectory
@@ -514,6 +515,11 @@ var errorCodeResponse = map[ErrorCode]APIError{
 		Description:    "Your request was missing a required header",
 		HTTPStatusCode: http.StatusNotFound,
 	},
+	ErrInvalidMetadataDirective: {
+		Code:           "InvalidArgument",
+		Description:    "Unknown metadata directive.",
+		HTTPStatusCode: http.StatusBadRequest,
+	},
 
 	// non aws errors
 	ErrExistingObjectIsDirectory: {

tests/integration/group-tests.go

@@ -199,6 +199,7 @@ func TestCopyObject(s *S3Conf) {
 	CopyObject_non_existing_dst_bucket(s)
 	CopyObject_not_owned_source_bucket(s)
 	CopyObject_copy_to_itself(s)
+	CopyObject_copy_to_itself_invalid_directive(s)
 	CopyObject_to_itself_with_new_metadata(s)
 	CopyObject_CopySource_starting_with_slash(s)
 	CopyObject_non_existing_dir_object(s)
@@ -620,6 +621,7 @@ func GetIntTests() IntTests {
 		"CopyObject_non_existing_dst_bucket":                                  CopyObject_non_existing_dst_bucket,
 		"CopyObject_not_owned_source_bucket":                                  CopyObject_not_owned_source_bucket,
 		"CopyObject_copy_to_itself":                                           CopyObject_copy_to_itself,
+		"CopyObject_copy_to_itself_invalid_directive":                         CopyObject_copy_to_itself_invalid_directive,
 		"CopyObject_to_itself_with_new_metadata":                              CopyObject_to_itself_with_new_metadata,
 		"CopyObject_CopySource_starting_with_slash":                           CopyObject_CopySource_starting_with_slash,
 		"CopyObject_non_existing_dir_object":                                  CopyObject_non_existing_dir_object,

tests/integration/tests.go

@@ -4268,6 +4268,29 @@ func CopyObject_copy_to_itself(s *S3Conf) error {
 	})
 }
 
+func CopyObject_copy_to_itself_invalid_directive(s *S3Conf) error {
+	testName := "CopyObject_copy_to_itself_invalid_directive"
+	return actionHandler(s, testName, func(s3client *s3.Client, bucket string) error {
+		obj := "my-obj"
+		err := putObjects(s3client, []string{obj}, bucket)
+		if err != nil {
+			return err
+		}
+		ctx, cancel := context.WithTimeout(context.Background(), shortTimeout)
+		_, err = s3client.CopyObject(ctx, &s3.CopyObjectInput{
+			Bucket:            &bucket,
+			Key:               &obj,
+			CopySource:        getPtr(fmt.Sprintf("%v/%v", bucket, obj)),
+			MetadataDirective: types.MetadataDirective("invalid"),
+		})
+		cancel()
+		if err := checkApiErr(err, s3err.GetAPIError(s3err.ErrInvalidMetadataDirective)); err != nil {
+			return err
+		}
+		return nil
+	})
+}
+
 func CopyObject_to_itself_with_new_metadata(s *S3Conf) error {
 	testName := "CopyObject_to_itself_with_new_metadata"
 	return actionHandler(s, testName, func(s3client *s3.Client, bucket string) error {
@@ -4284,6 +4307,7 @@ func CopyObject_to_itself_with_new_metadata(s *S3Conf) error {
 			Metadata: map[string]string{
 				"Hello": "World",
 			},
+			MetadataDirective: types.MetadataDirectiveReplace,
 		})
 		cancel()
 		if err != nil {