FS: remove .minio directory if .minio/multipart is empty. (#1899)

fixes #1886

object-common.go

@@ -17,9 +17,11 @@
 package main
 
 import (
+	"os"
 	"path/filepath"
 	"strings"
 	"sync"
+	"syscall"
 )
 
 const (
@@ -27,6 +29,17 @@ const (
 	blockSizeV1 = 10 * 1024 * 1024 // 10MiB.
 )
 
+// Register callback functions that needs to be called when process shutsdown.
+// For now, SIGINT triggers the callbacks, in future controller can trigger
+// shutdown callbacks.
+func registerShutdown(callback func()) {
+	go func() {
+		trapCh := signalTrap(os.Interrupt, syscall.SIGTERM)
+		<-trapCh
+		callback()
+	}()
+}
+
 // House keeping code needed for FS.
 func fsHouseKeeping(storageDisk StorageAPI) error {
 	// Attempt to create `.minio`.