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>

pkg/apparmor/apparmor_linux.go

@@ -17,7 +17,6 @@
 package apparmor
 
 import (
-	"io/ioutil"
 	"os"
 	"sync"
 )
@@ -36,7 +35,7 @@ func hostSupports() bool {
 	checkAppArmor.Do(func() {
 		// see https://github.com/opencontainers/runc/blob/0d49470392206f40eaab3b2190a57fe7bb3df458/libcontainer/apparmor/apparmor_linux.go
 		if _, err := os.Stat("/sys/kernel/security/apparmor"); err == nil && os.Getenv("container") == "" {
-			buf, err := ioutil.ReadFile("/sys/module/apparmor/parameters/enabled")
+			buf, err := os.ReadFile("/sys/module/apparmor/parameters/enabled")
 			appArmorSupported = err == nil && len(buf) > 1 && buf[0] == 'Y'
 		}
 	})

pkg/cri/io/logger.go

@@ -21,7 +21,6 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"time"
 
 	"github.com/sirupsen/logrus"
@@ -43,7 +42,7 @@ const (
 
 // NewDiscardLogger creates logger which discards all the input.
 func NewDiscardLogger() io.WriteCloser {
-	return cioutil.NewNopWriteCloser(ioutil.Discard)
+	return cioutil.NewNopWriteCloser(io.Discard)
 }
 
 // NewCRILogger returns a write closer which redirect container log into

pkg/cri/io/logger_test.go

@@ -18,7 +18,7 @@ package io
 
 import (
 	"bytes"
-	"io/ioutil"
+	"io"
 	"strings"
 	"testing"
 	"time"
@@ -237,7 +237,7 @@ func TestRedirectLogs(t *testing.T) {
 		},
 	} {
 		t.Logf("TestCase %q", desc)
-		rc := ioutil.NopCloser(strings.NewReader(test.input))
+		rc := io.NopCloser(strings.NewReader(test.input))
 		buf := bytes.NewBuffer(nil)
 		wc := cioutil.NewNopWriteCloser(buf)
 		redirectLogs("test-path", rc, wc, test.stream, test.maxLen)

pkg/cri/opts/container.go

@@ -18,7 +18,6 @@ package opts
 
 import (
 	"context"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 
@@ -67,7 +66,7 @@ func WithVolumes(volumeMounts map[string]string) containerd.NewContainerOpts {
 		if err != nil {
 			return err
 		}
-		root, err := ioutil.TempDir("", "ctd-volume")
+		root, err := os.MkdirTemp("", "ctd-volume")
 		if err != nil {
 			return err
 		}
@@ -108,7 +107,7 @@ func WithVolumes(volumeMounts map[string]string) containerd.NewContainerOpts {
 // copyExistingContents copies from the source to the destination and
 // ensures the ownership is appropriately set.
 func copyExistingContents(source, destination string) error {
-	dstList, err := ioutil.ReadDir(destination)
+	dstList, err := os.ReadDir(destination)
 	if err != nil {
 		return err
 	}

pkg/cri/opts/spec_linux.go

@@ -19,7 +19,6 @@ package opts
 import (
 	"context"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"sort"
@@ -533,7 +532,7 @@ var (
 // cgroup v1.
 func cgroupv1HasHugetlb() (bool, error) {
 	_cgroupv1HasHugetlbOnce.Do(func() {
-		if _, err := ioutil.ReadDir("/sys/fs/cgroup/hugetlb"); err != nil {
+		if _, err := os.ReadDir("/sys/fs/cgroup/hugetlb"); err != nil {
 			_cgroupv1HasHugetlbErr = errors.Wrap(err, "readdir /sys/fs/cgroup/hugetlb")
 			_cgroupv1HasHugetlb = false
 		} else {
@@ -548,7 +547,7 @@ func cgroupv1HasHugetlb() (bool, error) {
 // cgroup v2.
 func cgroupv2HasHugetlb() (bool, error) {
 	_cgroupv2HasHugetlbOnce.Do(func() {
-		controllers, err := ioutil.ReadFile("/sys/fs/cgroup/cgroup.controllers")
+		controllers, err := os.ReadFile("/sys/fs/cgroup/cgroup.controllers")
 		if err != nil {
 			_cgroupv2HasHugetlbErr = errors.Wrap(err, "read /sys/fs/cgroup/cgroup.controllers")
 			return
@@ -696,7 +695,7 @@ func nullOpt(_ context.Context, _ oci.Client, _ *containers.Container, _ *runtim
 }
 
 func getCurrentOOMScoreAdj() (int, error) {
-	b, err := ioutil.ReadFile("/proc/self/oom_score_adj")
+	b, err := os.ReadFile("/proc/self/oom_score_adj")
 	if err != nil {
 		return 0, errors.Wrap(err, "could not get the daemon oom_score_adj")
 	}

pkg/cri/server/helpers_linux_test.go

@@ -17,7 +17,6 @@
 package server
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -66,11 +65,11 @@ func TestEnsureRemoveAllWithMount(t *testing.T) {
 		t.Skip("skipping test that requires root")
 	}
 
-	dir1, err := ioutil.TempDir("", "test-ensure-removeall-with-dir1")
+	dir1, err := os.MkdirTemp("", "test-ensure-removeall-with-dir1")
 	if err != nil {
 		t.Fatal(err)
 	}
-	dir2, err := ioutil.TempDir("", "test-ensure-removeall-with-dir2")
+	dir2, err := os.MkdirTemp("", "test-ensure-removeall-with-dir2")
 	if err != nil {
 		t.Fatal(err)
 	}

pkg/cri/server/helpers_test.go

@@ -18,7 +18,7 @@ package server
 
 import (
 	"context"
-	"io/ioutil"
+	"os"
 	"testing"
 	"time"
 
@@ -489,7 +489,7 @@ func TestEnsureRemoveAllNotExist(t *testing.T) {
 }
 
 func TestEnsureRemoveAllWithDir(t *testing.T) {
-	dir, err := ioutil.TempDir("", "test-ensure-removeall-with-dir")
+	dir, err := os.MkdirTemp("", "test-ensure-removeall-with-dir")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -499,7 +499,7 @@ func TestEnsureRemoveAllWithDir(t *testing.T) {
 }
 
 func TestEnsureRemoveAllWithFile(t *testing.T) {
-	tmp, err := ioutil.TempFile("", "test-ensure-removeall-with-dir")
+	tmp, err := os.CreateTemp("", "test-ensure-removeall-with-dir")
 	if err != nil {
 		t.Fatal(err)
 	}

pkg/cri/server/image_pull.go

@@ -21,10 +21,10 @@ import (
 	"crypto/x509"
 	"encoding/base64"
 	"fmt"
-	"io/ioutil"
 	"net"
 	"net/http"
 	"net/url"
+	"os"
 	"path/filepath"
 	"strings"
 	"time"
@@ -301,7 +301,7 @@ func (c *criService) getTLSConfig(registryTLSConfig criconfig.TLSConfig) (*tls.C
 		if err != nil {
 			return nil, errors.Wrap(err, "failed to get system cert pool")
 		}
-		caCert, err := ioutil.ReadFile(registryTLSConfig.CAFile)
+		caCert, err := os.ReadFile(registryTLSConfig.CAFile)
 		if err != nil {
 			return nil, errors.Wrap(err, "failed to load CA file")
 		}

pkg/cri/server/restart.go

@@ -17,7 +17,6 @@
 package server
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	goruntime "runtime"
@@ -458,7 +457,7 @@ func (c *criService) loadImages(ctx context.Context, cImages []containerd.Image)
 
 func cleanupOrphanedIDDirs(ctx context.Context, cntrs []containerd.Container, base string) error {
 	// Cleanup orphaned id directories.
-	dirs, err := ioutil.ReadDir(base)
+	dirs, err := os.ReadDir(base)
 	if err != nil && !os.IsNotExist(err) {
 		return errors.Wrap(err, "failed to read base directory")
 	}

pkg/cri/server/service_test.go

@@ -18,7 +18,6 @@ package server
 
 import (
 	"encoding/json"
-	"io/ioutil"
 	"os"
 	"testing"
 
@@ -73,7 +72,7 @@ func newTestCRIService() *criService {
 func TestLoadBaseOCISpec(t *testing.T) {
 	spec := oci.Spec{Version: "1.0.2", Hostname: "default"}
 
-	file, err := ioutil.TempFile("", "spec-test-")
+	file, err := os.CreateTemp("", "spec-test-")
 	require.NoError(t, err)
 
 	defer func() {

pkg/cri/server/update_runtime_config_test.go

@@ -17,7 +17,6 @@
 package server
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -94,11 +93,11 @@ func TestUpdateRuntimeConfig(t *testing.T) {
 		},
 	} {
 		t.Run(name, func(t *testing.T) {
-			testDir, err := ioutil.TempDir(os.TempDir(), "test-runtime-config")
+			testDir, err := os.MkdirTemp(os.TempDir(), "test-runtime-config")
 			require.NoError(t, err)
 			defer os.RemoveAll(testDir)
 			templateName := filepath.Join(testDir, "template")
-			err = ioutil.WriteFile(templateName, []byte(testTemplate), 0666)
+			err = os.WriteFile(templateName, []byte(testTemplate), 0666)
 			require.NoError(t, err)
 			confDir := filepath.Join(testDir, "net.d")
 			confName := filepath.Join(confDir, cniConfigFileName)
@@ -131,7 +130,7 @@ func TestUpdateRuntimeConfig(t *testing.T) {
 				_, err := os.Stat(confName)
 				assert.Error(t, err)
 			} else {
-				got, err := ioutil.ReadFile(confName)
+				got, err := os.ReadFile(confName)
 				assert.NoError(t, err)
 				assert.Equal(t, expected, string(got))
 			}

pkg/cri/store/container/status.go

@@ -18,7 +18,6 @@ package container
 
 import (
 	"encoding/json"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"sync"
@@ -182,7 +181,7 @@ func StoreStatus(root, id string, status Status) (StatusStorage, error) {
 // writing to the file during loading.
 func LoadStatus(root, id string) (Status, error) {
 	path := filepath.Join(root, "status")
-	data, err := ioutil.ReadFile(path)
+	data, err := os.ReadFile(path)
 	if err != nil {
 		return Status{}, errors.Wrapf(err, "failed to read status from %q", path)
 	}

pkg/cri/store/container/status_test.go

@@ -19,7 +19,6 @@ package container
 import (
 	"encoding/json"
 	"errors"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -115,7 +114,7 @@ func TestStatus(t *testing.T) {
 	assert := assertlib.New(t)
 	require := requirelib.New(t)
 
-	tempDir, err := ioutil.TempDir(os.TempDir(), "status-test")
+	tempDir, err := os.MkdirTemp(os.TempDir(), "status-test")
 	require.NoError(err)
 	defer os.RemoveAll(tempDir)
 	statusFile := filepath.Join(tempDir, "status")

pkg/cri/store/image/sort_test.go

@@ -18,7 +18,6 @@ package image
 
 import (
 	"io"
-	"io/ioutil"
 	"math/rand"
 	"testing"
 
@@ -27,7 +26,7 @@ import (
 
 func TestReferenceSorting(t *testing.T) {
 	digested := func(seed int64) string {
-		b, err := ioutil.ReadAll(io.LimitReader(rand.New(rand.NewSource(seed)), 64))
+		b, err := io.ReadAll(io.LimitReader(rand.New(rand.NewSource(seed)), 64))
 		if err != nil {
 			panic(err)
 		}

pkg/ioutil/write_closer_test.go

@@ -17,7 +17,6 @@
 package ioutil
 
 import (
-	"io/ioutil"
 	"os"
 	"sort"
 	"strconv"
@@ -69,7 +68,7 @@ func TestSerialWriteCloser(t *testing.T) {
 			testData[i] = []byte(repeatNumber(i, dataLen) + "\n")
 		}
 
-		f, err := ioutil.TempFile("", "serial-write-closer")
+		f, err := os.CreateTemp("", "serial-write-closer")
 		require.NoError(t, err)
 		defer os.RemoveAll(f.Name())
 		defer f.Close()
@@ -91,7 +90,7 @@ func TestSerialWriteCloser(t *testing.T) {
 		wc.Close()
 
 		// Check test result
-		content, err := ioutil.ReadFile(f.Name())
+		content, err := os.ReadFile(f.Name())
 		require.NoError(t, err)
 		resultData := strings.Split(strings.TrimSpace(string(content)), "\n")
 		require.Len(t, resultData, goroutine)

pkg/os/os.go

@@ -18,7 +18,6 @@ package os
 
 import (
 	"io"
-	"io/ioutil"
 	"os"
 
 	"github.com/moby/sys/symlink"
@@ -78,9 +77,9 @@ func (RealOS) CopyFile(src, dest string, perm os.FileMode) error {
 	return err
 }
 
-// WriteFile will call ioutil.WriteFile to write data into a file.
+// WriteFile will call os.WriteFile to write data into a file.
 func (RealOS) WriteFile(filename string, data []byte, perm os.FileMode) error {
-	return ioutil.WriteFile(filename, data, perm)
+	return os.WriteFile(filename, data, perm)
 }
 
 // Hostname will call os.Hostname to get the hostname of the host.

pkg/os/os_windows_test.go

@@ -19,7 +19,6 @@ package os
 import (
 	"context"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -162,7 +161,7 @@ func setupVHDVolume(t *testing.T, vhdPath string) string {
 }
 
 func writeFile(t *testing.T, path string, content []byte) {
-	if err := ioutil.WriteFile(path, content, 0644); err != nil {
+	if err := os.WriteFile(path, content, 0644); err != nil {
 		t.Fatal(err)
 	}
 }

pkg/process/io_test.go

@@ -21,8 +21,8 @@ package process
 
 import (
 	"context"
-	"io/ioutil"
 	"net/url"
+	"os"
 	"testing"
 
 	"github.com/containerd/containerd/namespaces"
@@ -68,6 +68,6 @@ func TestNewBinaryIOCleanup(t *testing.T) {
 
 func descriptorCount(t *testing.T) int {
 	t.Helper()
-	files, _ := ioutil.ReadDir("/proc/self/fd")
+	files, _ := os.ReadDir("/proc/self/fd")
 	return len(files)
 }

pkg/testutil/helpers.go

@@ -19,7 +19,6 @@ package testutil
 import (
 	"flag"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -53,7 +52,7 @@ func DumpDir(t *testing.T, root string) {
 			}
 			t.Log(fi.Mode(), fmt.Sprintf("%10s", ""), path, "->", target)
 		} else if fi.Mode().IsRegular() {
-			p, err := ioutil.ReadFile(path)
+			p, err := os.ReadFile(path)
 			if err != nil {
 				t.Logf("error reading file: %v", err)
 				return nil