add integration test for --workdir=/

Docker-DCO-1.1-Signed-off-by: Tibor Vass <teabee89@gmail.com> (github: tiborvass)
Upstream-commit: baacc7006b35badb2e9ba807451ab158936d7832
Component: engine

components/engine/integration-cli/docker_cli_run_test.go

@@ -945,4 +945,18 @@ func TestModeHostname(t *testing.T) {
 	deleteAllContainers()
 
 	logDone("run - hostname and several network modes")
-}
+}
+
+func TestRootWorkdir(t *testing.T) {
+	s, _, err := cmd(t, "run", "--workdir", "/", "busybox", "pwd")
+	if err != nil {
+		t.Fatal(s, err)
+	}
+	if s != "/\n" {
+		t.Fatalf("pwd returned '%s' (expected /\\n)", s)
+	}
+
+	deleteAllContainers()
+
+	logDone("run - workdir /")
+}

components/engine/pkg/symlink/fs.go

@@ -27,13 +27,12 @@ func FollowSymlinkInScope(link, root string) (string, error) {
 		return root, nil
 	}
 
-
 	if !strings.HasPrefix(filepath.Dir(link), root) {
 		return "", fmt.Errorf("%s is not within %s", link, root)
 	}
 
 	prev := "/"
-	
+
 	for _, p := range strings.Split(link, "/") {
 		prev = filepath.Join(prev, p)
 		prev = filepath.Clean(prev)