Don't make modifications to /dev there are no devices in the configur…

…ation

Signed-off-by: Mrunal Patel <mrunalp@gmail.com>

libcontainer/rootfs_linux.go

@@ -27,6 +27,8 @@ func setupRootfs(config *configs.Config, console *linuxConsole) (err error) {
 	if err := prepareRoot(config); err != nil {
 		return newSystemError(err)
 	}
+
+	setupDev := len(config.Devices) == 0
 	for _, m := range config.Mounts {
 		for _, precmd := range m.PremountCmds {
 			if err := mountCmd(precmd); err != nil {
@@ -43,14 +45,16 @@ func setupRootfs(config *configs.Config, console *linuxConsole) (err error) {
 			}
 		}
 	}
-	if err := createDevices(config); err != nil {
-		return newSystemError(err)
-	}
-	if err := setupPtmx(config, console); err != nil {
-		return newSystemError(err)
-	}
-	if err := setupDevSymlinks(config.Rootfs); err != nil {
-		return newSystemError(err)
+	if !setupDev {
+		if err := createDevices(config); err != nil {
+			return newSystemError(err)
+		}
+		if err := setupPtmx(config, console); err != nil {
+			return newSystemError(err)
+		}
+		if err := setupDevSymlinks(config.Rootfs); err != nil {
+			return newSystemError(err)
+		}
 	}
 	if err := syscall.Chdir(config.Rootfs); err != nil {
 		return newSystemError(err)
@@ -63,8 +67,10 @@ func setupRootfs(config *configs.Config, console *linuxConsole) (err error) {
 	if err != nil {
 		return newSystemError(err)
 	}
-	if err := reOpenDevNull(config.Rootfs); err != nil {
-		return newSystemError(err)
+	if !setupDev {
+		if err := reOpenDevNull(config.Rootfs); err != nil {
+			return newSystemError(err)
+		}
 	}
 	if config.Readonlyfs {
 		if err := setReadonly(); err != nil {