refactor: move from io/ioutil to io and os package

The io/ioutil package has been deprecated as of Go 1.16, see
https://golang.org/doc/go1.16#ioutil. This commit replaces the existing
io/ioutil functions with their new definitions in io and os packages.

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

mount/fmountat_linux_test.go

@@ -17,7 +17,6 @@
 package mount
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"syscall"
@@ -46,7 +45,7 @@ func makeTestForFMountat(fn fMountatCaseFunc) func(t *testing.T) {
 	return func(t *testing.T) {
 		t.Parallel()
 
-		suiteDir, err := ioutil.TempDir("", "fmountat-test-")
+		suiteDir, err := os.MkdirTemp("", "fmountat-test-")
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -94,7 +93,7 @@ func testFMountatNormal(t *testing.T, root string) {
 	defer umount(t, fsdir)
 
 	// check hi file
-	content, err := ioutil.ReadFile(filepath.Join(fsdir, "hi"))
+	content, err := os.ReadFile(filepath.Join(fsdir, "hi"))
 	if err != nil {
 		t.Fatalf("failed to read file: %+v", err)
 	}

mount/lookup_linux_test.go

@@ -18,7 +18,6 @@ package mount
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -42,7 +41,7 @@ func checkLookup(t *testing.T, fsType, mntPoint, dir string) {
 
 func testLookup(t *testing.T, fsType string) {
 	testutil.RequiresRoot(t)
-	mnt, err := ioutil.TempDir("", "containerd-mountinfo-test-lookup")
+	mnt, err := os.MkdirTemp("", "containerd-mountinfo-test-lookup")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -69,7 +68,7 @@ func testLookup(t *testing.T, fsType string) {
 	assert.Check(t, strings.HasPrefix(loop.Device, "/dev/loop"))
 	checkLookup(t, fsType, mnt, mnt)
 
-	newMnt, err := ioutil.TempDir("", "containerd-mountinfo-test-newMnt")
+	newMnt, err := os.MkdirTemp("", "containerd-mountinfo-test-newMnt")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -100,19 +99,19 @@ func TestLookupWithXFS(t *testing.T) {
 }
 
 func TestLookupWithOverlay(t *testing.T) {
-	lower, err := ioutil.TempDir("", "containerd-mountinfo-test-lower")
+	lower, err := os.MkdirTemp("", "containerd-mountinfo-test-lower")
 	assert.NilError(t, err)
 	defer os.RemoveAll(lower)
 
-	upper, err := ioutil.TempDir("", "containerd-mountinfo-test-upper")
+	upper, err := os.MkdirTemp("", "containerd-mountinfo-test-upper")
 	assert.NilError(t, err)
 	defer os.RemoveAll(upper)
 
-	work, err := ioutil.TempDir("", "containerd-mountinfo-test-work")
+	work, err := os.MkdirTemp("", "containerd-mountinfo-test-work")
 	assert.NilError(t, err)
 	defer os.RemoveAll(work)
 
-	overlay, err := ioutil.TempDir("", "containerd-mountinfo-test-overlay")
+	overlay, err := os.MkdirTemp("", "containerd-mountinfo-test-overlay")
 	assert.NilError(t, err)
 	defer os.RemoveAll(overlay)
 

mount/losetup_linux_test.go

@@ -17,7 +17,6 @@
 package mount
 
 import (
-	"io/ioutil"
 	"os"
 	"testing"
 
@@ -29,7 +28,7 @@ var randomData = []byte("randomdata")
 func createTempFile(t *testing.T) string {
 	t.Helper()
 
-	f, err := ioutil.TempFile("", "losetup")
+	f, err := os.CreateTemp("", "losetup")
 	if err != nil {
 		t.Fatal(err)
 	}

mount/mount_linux_test.go

@@ -18,7 +18,6 @@ package mount
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -105,7 +104,7 @@ func TestFUSEHelper(t *testing.T) {
 	if err != nil {
 		t.Skip("fuse-overlayfs not installed")
 	}
-	td, err := ioutil.TempDir("", "fuse")
+	td, err := os.MkdirTemp("", "fuse")
 	if err != nil {
 		t.Fatal(err)
 	}

mount/temp.go

@@ -18,7 +18,6 @@ package mount
 
 import (
 	"context"
-	"io/ioutil"
 	"os"
 
 	"github.com/containerd/containerd/log"
@@ -31,7 +30,7 @@ var tempMountLocation = getTempDir()
 // The mounts are valid during the call to the f.
 // Finally we will unmount and remove the temp dir regardless of the result of f.
 func WithTempMount(ctx context.Context, mounts []Mount, f func(root string) error) (err error) {
-	root, uerr := ioutil.TempDir(tempMountLocation, "containerd-mount")
+	root, uerr := os.MkdirTemp(tempMountLocation, "containerd-mount")
 	if uerr != nil {
 		return errors.Wrapf(uerr, "failed to create temp dir")
 	}