From 52b55afce072579c11944aeaf94ff16a988ab54a Mon Sep 17 00:00:00 2001
From: Bala FA <bala.gluster@gmail.com>
Date: Mon, 4 Jul 2016 08:31:40 +0530
Subject: [PATCH] FS: check whether disk format is FS or not. (#2083)

Fixes #2060
---
 fs-v1-errors.go   | 22 ++++++++++++++++++++++
 fs-v1-metadata.go |  5 +++++
 fs-v1.go          |  4 +++-
 fs-v1_test.go     | 28 +++++++++++++++++++++++++---
 4 files changed, 55 insertions(+), 4 deletions(-)
 create mode 100644 fs-v1-errors.go

diff --git a/fs-v1-errors.go b/fs-v1-errors.go
new file mode 100644
index 000000000..f2f3f3100
--- /dev/null
+++ b/fs-v1-errors.go
@@ -0,0 +1,22 @@
+/*
+ * Minio Cloud Storage, (C) 2016 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 main
+
+import "errors"
+
+// errFSDiskFormat - returned when given disk format is other than FS format.
+var errFSDiskFormat = errors.New("Disk is not in FS format.")
diff --git a/fs-v1-metadata.go b/fs-v1-metadata.go
index 7399b446b..d4070235f 100644
--- a/fs-v1-metadata.go
+++ b/fs-v1-metadata.go
@@ -93,6 +93,11 @@ func newFSFormatV1() (format formatConfigV1) {
 	}
 }
 
+// isFSFormat - returns whether given formatConfigV1 is FS type or not.
+func isFSFormat(format formatConfigV1) bool {
+	return format.Format == "fs"
+}
+
 // writes FS format (format.json) into minioMetaBucket.
 func writeFSFormatData(storage StorageAPI, fsFormat formatConfigV1) error {
 	metadataBytes, err := json.Marshal(fsFormat)
diff --git a/fs-v1.go b/fs-v1.go
index 0dd67ec73..cc1c416b1 100644
--- a/fs-v1.go
+++ b/fs-v1.go
@@ -103,7 +103,7 @@ func newFSObjects(disk string) (ObjectLayer, error) {
 
 	// loading format.json from minioMetaBucket.
 	// Note: The format.json content is ignored, reserved for future use.
-	_, err = loadFormatFS(storage)
+	format, err := loadFormatFS(storage)
 	if err != nil {
 		if err == errFileNotFound {
 			// format.json doesn't exist, create it inside minioMetaBucket.
@@ -114,6 +114,8 @@ func newFSObjects(disk string) (ObjectLayer, error) {
 		} else {
 			return nil, err
 		}
+	} else if !isFSFormat(format) {
+		return nil, errFSDiskFormat
 	}
 
 	// Register the callback that should be called when the process shuts down.
diff --git a/fs-v1_test.go b/fs-v1_test.go
index 49f9e6131..8e6a2ad36 100644
--- a/fs-v1_test.go
+++ b/fs-v1_test.go
@@ -31,9 +31,31 @@ func TestNewFS(t *testing.T) {
 	disk := filepath.Join(os.TempDir(), "minio-"+nextSuffix())
 	defer removeAll(disk)
 
-	// Initializes single disk, validate if there is no error.
-	_, err := newFSObjects(disk)
+	// Setup to test errFSDiskFormat.
+	disks := []string{}
+	for i := 0; i < 6; i++ {
+		xlDisk := filepath.Join(os.TempDir(), "minio-"+nextSuffix())
+		defer removeAll(xlDisk)
+		disks = append(disks, xlDisk)
+	}
+
+	// Initializes all disks with XL
+	_, err := newXLObjects(disks)
 	if err != nil {
-		t.Fatalf("Unable to initialize erasure, %s", err)
+		t.Fatalf("Unable to initialize XL object, %s", err)
+	}
+
+	testCases := []struct {
+		disk        string
+		expectedErr error
+	}{
+		{disk, nil},
+		{disks[0], errFSDiskFormat},
+	}
+
+	for _, testCase := range testCases {
+		if _, err := newFSObjects(testCase.disk); err != testCase.expectedErr {
+			t.Fatalf("expected: %s, got: %s", testCase.expectedErr, err)
+		}
 	}
 }