Add ownership inspection to mount tester image

hack/verify-flags/excluded-flags.txt

@@ -3,6 +3,7 @@ concurrent_rc_syncs
 etcd_mutation_timeout
 file_content
 file_mode
+file_owner
 file_perm
 fs_type
 gke_context
@@ -12,6 +13,7 @@ kube_master_url
 max_in_flight
 max_par
 new_file_0644
+new_file_0660
 new_file_0666
 new_file_0777
 pods_per_node

test/images/mount-tester-user/Dockerfile

@@ -12,5 +12,5 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM gcr.io/google_containers/mounttest:0.4
+FROM gcr.io/google_containers/mounttest:0.5
 USER 1001

test/images/mount-tester-user/Makefile

@@ -1,6 +1,6 @@
 all: push
 
-TAG = 0.2
+TAG = 0.3
 
 image:
 	sudo docker build -t gcr.io/google_containers/mounttest-user:$(TAG) .

test/images/mount-tester/Makefile

@@ -1,6 +1,6 @@
 all: push
 
-TAG = 0.4
+TAG = 0.5
 
 mt: mt.go
 	CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -ldflags '-w' ./mt.go

test/images/mount-tester/mt.go

@@ -29,8 +29,10 @@ var (
 	fsTypePath                = ""
 	fileModePath              = ""
 	filePermPath              = ""
+	fileOwnerPath             = ""
 	newFilePath0644           = ""
 	newFilePath0666           = ""
+	newFilePath0660           = ""
 	newFilePath0777           = ""
 	readFileContentPath       = ""
 	readFileContentInLoopPath = ""
@@ -41,8 +43,10 @@ func init() {
 	flag.StringVar(&fsTypePath, "fs_type", "", "Path to print the fs type for")
 	flag.StringVar(&fileModePath, "file_mode", "", "Path to print the mode bits of")
 	flag.StringVar(&filePermPath, "file_perm", "", "Path to print the perms of")
+	flag.StringVar(&fileOwnerPath, "file_owner", "", "Path to print the owning UID and GID of")
 	flag.StringVar(&newFilePath0644, "new_file_0644", "", "Path to write to and read from with perm 0644")
 	flag.StringVar(&newFilePath0666, "new_file_0666", "", "Path to write to and read from with perm 0666")
+	flag.StringVar(&newFilePath0660, "new_file_0660", "", "Path to write to and read from with perm 0660")
 	flag.StringVar(&newFilePath0777, "new_file_0777", "", "Path to write to and read from with perm 0777")
 	flag.StringVar(&readFileContentPath, "file_content", "", "Path to read the file content from")
 	flag.StringVar(&readFileContentInLoopPath, "file_content_in_loop", "", "Path to read the file content in loop from")
@@ -86,6 +90,11 @@ func main() {
 		errs = append(errs, err)
 	}
 
+	err = readWriteNewFile(newFilePath0660, 0660)
+	if err != nil {
+		errs = append(errs, err)
+	}
+
 	err = readWriteNewFile(newFilePath0777, 0777)
 	if err != nil {
 		errs = append(errs, err)
@@ -101,6 +110,11 @@ func main() {
 		errs = append(errs, err)
 	}
 
+	err = fileOwner(fileOwnerPath)
+	if err != nil {
+		errs = append(errs, err)
+	}
+
 	err = readFileContent(readFileContentPath)
 	if err != nil {
 		errs = append(errs, err)
@@ -171,6 +185,22 @@ func filePerm(path string) error {
 	return nil
 }
 
+func fileOwner(path string) error {
+	if path == "" {
+		return nil
+	}
+
+	buf := syscall.Stat_t{}
+	if err := syscall.Stat(path, &buf); err != nil {
+		fmt.Printf("error from stat(%q): %v\n", path, err)
+		return err
+	}
+
+	fmt.Printf("owner UID of %q: %v\n", path, buf.Uid)
+	fmt.Printf("owner GID of %q: %v\n", path, buf.Gid)
+	return nil
+}
+
 func readFileContent(path string) error {
 	if path == "" {
 		return nil