Minio handle for list_objects_v2 with a blank ContinuationToken (#5940)

minio will now return an error for a blank continuation token in list_objects_v2,so as in s3.

Fixes #5931

cmd/api-resources_test.go

@@ -29,6 +29,7 @@ func TestListObjectsV2Resources(t *testing.T) {
 		fetchOwner                           bool
 		maxKeys                              int
 		encodingType                         string
+		errCode                              APIErrorCode
 	}{
 		{
 			values: url.Values{
@@ -47,6 +48,7 @@ func TestListObjectsV2Resources(t *testing.T) {
 			fetchOwner:   true,
 			maxKeys:      100,
 			encodingType: "gzip",
+			errCode:      ErrNone,
 		},
 		{
 			values: url.Values{
@@ -64,11 +66,34 @@ func TestListObjectsV2Resources(t *testing.T) {
 			fetchOwner:   true,
 			maxKeys:      1000,
 			encodingType: "gzip",
+			errCode:      ErrNone,
+		},
+		{
+			values: url.Values{
+				"prefix":             []string{"photos/"},
+				"continuation-token": []string{""},
+				"start-after":        []string{"start-after"},
+				"delimiter":          []string{"/"},
+				"fetch-owner":        []string{"true"},
+				"encoding-type":      []string{"gzip"},
+			},
+			prefix:       "",
+			token:        "",
+			startAfter:   "",
+			delimiter:    "",
+			fetchOwner:   false,
+			maxKeys:      0,
+			encodingType: "",
+			errCode:      ErrIncorrectContinuationToken,
 		},
 	}
 
 	for i, testCase := range testCases {
-		prefix, token, startAfter, delimiter, fetchOwner, maxKeys, encodingType := getListObjectsV2Args(testCase.values)
+		prefix, token, startAfter, delimiter, fetchOwner, maxKeys, encodingType, errCode := getListObjectsV2Args(testCase.values)
+
+		if errCode != testCase.errCode {
+			t.Errorf("Test %d: Expected error code:%d, got %d", i+1, testCase.errCode, errCode)
+		}
 		if prefix != testCase.prefix {
 			t.Errorf("Test %d: Expected %s, got %s", i+1, testCase.prefix, prefix)
 		}