Enhance ExistsPath check

It should return error when the check fails (e.g. no permissions, symlink link
loop etc.)

pkg/kubelet/cm/container_manager_linux_test.go

@@ -92,8 +92,8 @@ func (mi *fakeMountInterface) MakeFile(pathname string) error {
 	return nil
 }
 
-func (mi *fakeMountInterface) ExistsPath(pathname string) bool {
-	return true
+func (mi *fakeMountInterface) ExistsPath(pathname string) (bool, error) {
+	return true, errors.New("not implemented")
 }
 
 func (mi *fakeMountInterface) PrepareSafeSubpath(subPath mount.Subpath) (newHostPath string, cleanupAction func(), err error) {

pkg/kubelet/kubelet_pods.go

@@ -60,7 +60,6 @@ import (
 	"k8s.io/kubernetes/pkg/kubelet/status"
 	kubetypes "k8s.io/kubernetes/pkg/kubelet/types"
 	"k8s.io/kubernetes/pkg/kubelet/util/format"
-	utilfile "k8s.io/kubernetes/pkg/util/file"
 	mountutil "k8s.io/kubernetes/pkg/util/mount"
 	volumeutil "k8s.io/kubernetes/pkg/volume/util"
 	"k8s.io/kubernetes/pkg/volume/util/volumepathhandler"
@@ -181,7 +180,7 @@ func makeMounts(pod *v1.Pod, podDir string, container *v1.Container, hostName, h
 			}
 			hostPath = filepath.Join(volumePath, mount.SubPath)
 
-			if subPathExists, err := utilfile.FileOrSymlinkExists(hostPath); err != nil {
+			if subPathExists, err := mounter.ExistsPath(hostPath); err != nil {
 				glog.Errorf("Could not determine if subPath %s exists; will not attempt to change its permissions", hostPath)
 			} else if !subPathExists {
 				// Create the sub path now because if it's auto-created later when referenced, it may have an

pkg/util/mount/BUILD

@@ -72,11 +72,15 @@ go_library(
         "//vendor/k8s.io/utils/exec:go_default_library",
     ] + select({
         "@io_bazel_rules_go//go/platform:linux": [
+            "//pkg/util/file:go_default_library",
             "//pkg/util/io:go_default_library",
             "//pkg/util/nsenter:go_default_library",
             "//vendor/golang.org/x/sys/unix:go_default_library",
             "//vendor/k8s.io/apimachinery/pkg/util/sets:go_default_library",
         ],
+        "@io_bazel_rules_go//go/platform:windows": [
+            "//pkg/util/file:go_default_library",
+        ],
         "//conditions:default": [],
     }),
 )

pkg/util/mount/exec_mount.go

@@ -136,7 +136,7 @@ func (m *execMounter) MakeDir(pathname string) error {
 	return m.wrappedMounter.MakeDir(pathname)
 }
 
-func (m *execMounter) ExistsPath(pathname string) bool {
+func (m *execMounter) ExistsPath(pathname string) (bool, error) {
 	return m.wrappedMounter.ExistsPath(pathname)
 }
 

pkg/util/mount/exec_mount_test.go

@@ -147,8 +147,8 @@ func (fm *fakeMounter) MakeFile(pathname string) error {
 func (fm *fakeMounter) MakeDir(pathname string) error {
 	return nil
 }
-func (fm *fakeMounter) ExistsPath(pathname string) bool {
-	return false
+func (fm *fakeMounter) ExistsPath(pathname string) (bool, error) {
+	return false, errors.New("not implemented")
 }
 func (fm *fakeMounter) GetFileType(pathname string) (FileType, error) {
 	return FileTypeFile, nil

pkg/util/mount/exec_mount_unsupported.go

@@ -83,8 +83,8 @@ func (mounter *execMounter) MakeFile(pathname string) error {
 	return nil
 }
 
-func (mounter *execMounter) ExistsPath(pathname string) bool {
-	return true
+func (mounter *execMounter) ExistsPath(pathname string) (bool, error) {
+	return true, errors.New("not implemented")
 }
 
 func (mounter *execMounter) PrepareSafeSubpath(subPath Subpath) (newHostPath string, cleanupAction func(), err error) {

pkg/util/mount/fake.go

@@ -201,8 +201,8 @@ func (f *FakeMounter) MakeFile(pathname string) error {
 	return nil
 }
 
-func (f *FakeMounter) ExistsPath(pathname string) bool {
-	return false
+func (f *FakeMounter) ExistsPath(pathname string) (bool, error) {
+	return false, errors.New("not implemented")
 }
 
 func (f *FakeMounter) PrepareSafeSubpath(subPath Subpath) (newHostPath string, cleanupAction func(), err error) {

pkg/util/mount/mount.go

@@ -91,9 +91,9 @@ type Interface interface {
 	// else. E.g. if the directory already exists, it may exists outside of the
 	// base due to symlinks.
 	SafeMakeDir(pathname string, base string, perm os.FileMode) error
-	// ExistsPath checks whether the path exists.
-	// Will operate in the host mount namespace if kubelet is running in a container
-	ExistsPath(pathname string) bool
+	// Will operate in the host mount namespace if kubelet is running in a container.
+	// Error is returned on any other error than "file not found".
+	ExistsPath(pathname string) (bool, error)
 	// CleanSubPaths removes any bind-mounts created by PrepareSafeSubpath in given
 	// pod volume directory.
 	CleanSubPaths(podDir string, volumeName string) error

pkg/util/mount/mount_linux.go

@@ -33,6 +33,7 @@ import (
 	"github.com/golang/glog"
 	"golang.org/x/sys/unix"
 	"k8s.io/apimachinery/pkg/util/sets"
+	utilfile "k8s.io/kubernetes/pkg/util/file"
 	utilio "k8s.io/kubernetes/pkg/util/io"
 	utilexec "k8s.io/utils/exec"
 )
@@ -447,12 +448,8 @@ func (mounter *Mounter) MakeFile(pathname string) error {
 	return nil
 }
 
-func (mounter *Mounter) ExistsPath(pathname string) bool {
-	_, err := os.Stat(pathname)
-	if err != nil {
-		return false
-	}
-	return true
+func (mounter *Mounter) ExistsPath(pathname string) (bool, error) {
+	return utilfile.FileExists(pathname)
 }
 
 // formatAndMount uses unix utils to format and mount the given disk

pkg/util/mount/mount_unsupported.go

@@ -21,8 +21,6 @@ package mount
 import (
 	"errors"
 	"os"
-
-	"github.com/golang/glog"
 )
 
 type Mounter struct {
@@ -110,9 +108,8 @@ func (mounter *Mounter) MakeFile(pathname string) error {
 	return unsupportedErr
 }
 
-func (mounter *Mounter) ExistsPath(pathname string) bool {
-	glog.Errorf("%s", unsupportedErr)
-	return true
+func (mounter *Mounter) ExistsPath(pathname string) (bool, error) {
+	return true, errors.New("not implemented")
 }
 
 func (mounter *Mounter) PrepareSafeSubpath(subPath Subpath) (newHostPath string, cleanupAction func(), err error) {

pkg/util/mount/mount_windows.go

@@ -29,6 +29,8 @@ import (
 	"syscall"
 
 	"github.com/golang/glog"
+
+	utilfile "k8s.io/kubernetes/pkg/util/file"
 )
 
 // Mounter provides the default implementation of mount.Interface
@@ -147,9 +149,13 @@ func (mounter *Mounter) IsLikelyNotMountPoint(file string) (bool, error) {
 	if stat.Mode()&os.ModeSymlink != 0 {
 		target, err := os.Readlink(file)
 		if err != nil {
-			return true, fmt.Errorf("Readlink error: %v", err)
+			return true, fmt.Errorf("readlink error: %v", err)
 		}
-		return !mounter.ExistsPath(target), nil
+		exists, err := mounter.ExistsPath(target)
+		if err != nil {
+			return true, err
+		}
+		return !exists, nil
 	}
 
 	return true, nil
@@ -232,12 +238,8 @@ func (mounter *Mounter) MakeFile(pathname string) error {
 }
 
 // ExistsPath checks whether the path exists
-func (mounter *Mounter) ExistsPath(pathname string) bool {
-	_, err := os.Stat(pathname)
-	if err != nil {
-		return false
-	}
-	return true
+func (mounter *Mounter) ExistsPath(pathname string) (bool, error) {
+	return utilfile.FileExists(pathname)
 }
 
 // check whether hostPath is within volume path

pkg/util/mount/nsenter_mount.go

@@ -27,6 +27,7 @@ import (
 	"strings"
 
 	"github.com/golang/glog"
+	utilfile "k8s.io/kubernetes/pkg/util/file"
 	utilio "k8s.io/kubernetes/pkg/util/io"
 	"k8s.io/kubernetes/pkg/util/nsenter"
 )
@@ -281,13 +282,15 @@ func (mounter *NsenterMounter) MakeFile(pathname string) error {
 	return nil
 }
 
-func (mounter *NsenterMounter) ExistsPath(pathname string) bool {
-	args := []string{pathname}
-	_, err := mounter.ne.Exec("ls", args).CombinedOutput()
-	if err == nil {
-		return true
+func (mounter *NsenterMounter) ExistsPath(pathname string) (bool, error) {
+	// Resolve the symlinks but allow the target not to exist. EvalSymlinks
+	// would return an generic error when the target does not exist.
+	hostPath, err := mounter.ne.EvalSymlinks(pathname, false /* mustExist */)
+	if err != nil {
+		return false, err
 	}
-	return false
+	kubeletpath := mounter.ne.KubeletPath(hostPath)
+	return utilfile.FileExists(kubeletpath)
 }
 
 func (mounter *NsenterMounter) CleanSubPaths(podDir string, volumeName string) error {

pkg/util/mount/nsenter_mount_unsupported.go

@@ -83,8 +83,8 @@ func (*NsenterMounter) MakeFile(pathname string) error {
 	return nil
 }
 
-func (*NsenterMounter) ExistsPath(pathname string) bool {
-	return true
+func (*NsenterMounter) ExistsPath(pathname string) (bool, error) {
+	return true, errors.New("not implemented")
 }
 
 func (*NsenterMounter) SafeMakeDir(pathname string, base string, perm os.FileMode) error {

pkg/util/removeall/removeall_test.go

@@ -75,8 +75,8 @@ func (mounter *fakeMounter) MakeFile(pathname string) error {
 	return nil
 }
 
-func (mounter *fakeMounter) ExistsPath(pathname string) bool {
-	return true
+func (mounter *fakeMounter) ExistsPath(pathname string) (bool, error) {
+	return true, errors.New("not implemented")
 }
 
 func (mounter *fakeMounter) PrepareSafeSubpath(subPath mount.Subpath) (newHostPath string, cleanupAction func(), err error) {

pkg/volume/host_path/host_path.go

@@ -350,7 +350,8 @@ type fileTypeChecker struct {
 }
 
 func (ftc *fileTypeChecker) Exists() bool {
-	return ftc.mounter.ExistsPath(ftc.path)
+	exists, err := ftc.mounter.ExistsPath(ftc.path)
+	return exists && err == nil
 }
 
 func (ftc *fileTypeChecker) IsFile() bool {

pkg/volume/host_path/host_path_test.go

@@ -369,8 +369,8 @@ func (fftc *fakeFileTypeChecker) MakeDir(pathname string) error {
 	return nil
 }
 
-func (fftc *fakeFileTypeChecker) ExistsPath(pathname string) bool {
-	return true
+func (fftc *fakeFileTypeChecker) ExistsPath(pathname string) (bool, error) {
+	return true, nil
 }
 
 func (fftc *fakeFileTypeChecker) GetFileType(_ string) (utilmount.FileType, error) {