fsStorage should use appendStorage with offsets

- also takes in 'blockSize' cli option.
 - robustness fixes

cmd/erasure-demo/fs.go

@@ -14,7 +14,7 @@ import (
 func fsGetList(config inputConfig) (io.Reader, error) {
 	var objectStorage storage.ObjectStorage
 	rootDir := path.Join(config.rootDir, config.storageDriver)
-	objectStorage, _ = fsstorage.NewStorage(rootDir)
+	objectStorage, _ = fsstorage.NewStorage(rootDir, config.blockSize)
 	objectList, err := objectStorage.List()
 	if err != nil {
 		return nil, err
@@ -30,7 +30,7 @@ func fsGetList(config inputConfig) (io.Reader, error) {
 func fsGet(config inputConfig, objectPath string) (io.Reader, error) {
 	var objectStorage storage.ObjectStorage
 	rootDir := path.Join(config.rootDir, config.storageDriver)
-	objectStorage, _ = fsstorage.NewStorage(rootDir)
+	objectStorage, _ = fsstorage.NewStorage(rootDir, config.blockSize)
 	object, err := objectStorage.Get(objectPath)
 	if err != nil {
 		return nil, err
@@ -45,7 +45,7 @@ func fsPut(config inputConfig, objectPath string, reader io.Reader) error {
 		return err
 	}
 	var objectStorage storage.ObjectStorage
-	objectStorage, _ = fsstorage.NewStorage(rootDir)
+	objectStorage, _ = fsstorage.NewStorage(rootDir, config.blockSize)
 	if err = objectStorage.Put(objectPath, reader); err != nil {
 		return err
 	}

cmd/erasure-demo/get.go

@@ -46,5 +46,8 @@ func get(c *cli.Context) {
 			log.Fatal("Unknown driver")
 		}
 	}
+	if objectReader == nil {
+		log.Fatal("Object not found")
+	}
 	io.Copy(os.Stdout, objectReader)
 }

cmd/erasure-demo/main.go

@@ -72,6 +72,16 @@ func main() {
 					Value: "erasure",
 					Usage: "erasure",
 				},
+				cli.StringFlag{
+					Name:  "protection-level",
+					Value: "10,6",
+					Usage: "data,parity",
+				},
+				cli.StringFlag{
+					Name:  "block-size",
+					Value: "1M",
+					Usage: "Size of blocks. Examples: 1K, 1M, full",
+				},
 			},
 		},
 		{