Fix missing CompleteMultipartUpload Etag. (#3227)

Fixes #3224

cmd/fs-v1-multipart.go

@@ -660,7 +660,7 @@ func (fs fsObjects) CompleteMultipartUpload(bucket string, object string, upload
 	defer appendPathLock.Unlock()
 
 	// Calculate s3 compatible md5sum for complete multipart.
-	s3MD5, err := getCompleteMultipartMD5(parts...)
+	s3MD5, err := getCompleteMultipartMD5(parts)
 	if err != nil {
 		return "", err
 	}

cmd/object-api-multipart_test.go

@@ -1864,7 +1864,7 @@ func testObjectCompleteMultipartUpload(obj ObjectLayer, instanceType string, t T
 			},
 		},
 	}
-	s3MD5, err := getCompleteMultipartMD5(inputParts[3].parts...)
+	s3MD5, err := getCompleteMultipartMD5(inputParts[3].parts)
 	if err != nil {
 		t.Fatalf("Obtaining S3MD5 failed")
 	}

cmd/object-handlers.go

@@ -877,7 +877,6 @@ func (api objectAPIHandlers) CompleteMultipartUploadHandler(w http.ResponseWrite
 	}
 
 	md5Sum, err = objectAPI.CompleteMultipartUpload(bucket, object, uploadID, completeParts)
-
 	if err != nil {
 		err = errorCause(err)
 		errorIf(err, "Unable to complete multipart upload.")
@@ -903,6 +902,9 @@ func (api objectAPIHandlers) CompleteMultipartUploadHandler(w http.ResponseWrite
 		return
 	}
 
+	// Set etag.
+	w.Header().Set("ETag", "\""+md5Sum+"\"")
+
 	// Write success response.
 	w.Write(encodedSuccessResponse)
 	w.(http.Flusher).Flush()

cmd/object-handlers_test.go

@@ -1507,7 +1507,7 @@ func testAPICompleteMultipartHandler(obj ObjectLayer, instanceType, bucketName s
 	}
 
 	// on successful complete multipart operation the s3MD5 for the parts uploaded will be returned.
-	s3MD5, err := getCompleteMultipartMD5(inputParts[3].parts...)
+	s3MD5, err := getCompleteMultipartMD5(inputParts[3].parts)
 	if err != nil {
 		t.Fatalf("Obtaining S3MD5 failed")
 	}

cmd/object-utils.go

@@ -141,7 +141,7 @@ func getUUID() (uuidStr string) {
 }
 
 // Create an s3 compatible MD5sum for complete multipart transaction.
-func getCompleteMultipartMD5(parts ...completePart) (string, error) {
+func getCompleteMultipartMD5(parts []completePart) (string, error) {
 	var finalMD5Bytes []byte
 	for _, part := range parts {
 		md5Bytes, err := hex.DecodeString(part.ETag)

cmd/object-utils_test.go

@@ -158,7 +158,7 @@ func TestGetCompleteMultipartMD5(t *testing.T) {
 	}
 
 	for i, test := range testCases {
-		result, err := getCompleteMultipartMD5(test.parts...)
+		result, err := getCompleteMultipartMD5(test.parts)
 		if result != test.expectedResult {
 			t.Fatalf("test %d failed: expected: result=%v, got=%v", i+1, test.expectedResult, result)
 		}

cmd/server_test.go

@@ -2503,5 +2503,12 @@ func (s *TestSuiteCommon) TestObjectMultipart(c *C) {
 	c.Assert(err, IsNil)
 	// verify whether complete multipart was successful.
 	c.Assert(response.StatusCode, Equals, http.StatusOK)
-
+	var parts []completePart
+	for _, part := range completeUploads.Parts {
+		part.ETag = strings.Trim(part.ETag, "\"")
+		parts = append(parts, part)
+	}
+	etag, err := getCompleteMultipartMD5(parts)
+	c.Assert(err, IsNil)
+	c.Assert(strings.Trim(response.Header.Get("Etag"), "\""), Equals, etag)
 }

cmd/xl-v1-multipart.go

@@ -664,7 +664,7 @@ func (xl xlObjects) CompleteMultipartUpload(bucket string, object string, upload
 		return "", traceError(InvalidUploadID{UploadID: uploadID})
 	}
 	// Calculate s3 compatible md5sum for complete multipart.
-	s3MD5, err := getCompleteMultipartMD5(parts...)
+	s3MD5, err := getCompleteMultipartMD5(parts)
 	if err != nil {
 		return "", err
 	}