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>

integration/client/client_test.go

@@ -22,7 +22,6 @@ import (
 	"flag"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"testing"
 	"time"
@@ -90,7 +89,7 @@ func TestMain(m *testing.M) {
 	if !noDaemon {
 		sys.ForceRemoveAll(defaultRoot)
 
-		stdioFile, err := ioutil.TempFile("", "")
+		stdioFile, err := os.CreateTemp("", "")
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "could not create a new stdio temp file: %s\n", err)
 			os.Exit(1)
@@ -497,7 +496,7 @@ func TestClientReconnect(t *testing.T) {
 }
 
 func createShimDebugConfig() string {
-	f, err := ioutil.TempFile("", "containerd-config-")
+	f, err := os.CreateTemp("", "containerd-config-")
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "Failed to create config file: %s\n", err)
 		os.Exit(1)

integration/client/container_checkpoint_test.go

@@ -22,7 +22,6 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -455,7 +454,7 @@ func TestCheckpointRestoreWithImagePath(t *testing.T) {
 	}
 
 	// create image path store criu image files
-	crDir, err := ioutil.TempDir("", "test-cr")
+	crDir, err := os.MkdirTemp("", "test-cr")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -473,7 +472,7 @@ func TestCheckpointRestoreWithImagePath(t *testing.T) {
 	task.Delete(ctx)
 
 	// check image files have been dumped into image path
-	if files, err := ioutil.ReadDir(imagePath); err != nil || len(files) == 0 {
+	if files, err := os.ReadDir(imagePath); err != nil || len(files) == 0 {
 		t.Fatal("failed to checkpoint with image path set")
 	}
 

integration/client/container_linux_test.go

@@ -21,7 +21,6 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -573,7 +572,7 @@ func TestDaemonReconnectsToShimIOPipesOnRestart(t *testing.T) {
 
 	<-statusC
 
-	stdioContents, err := ioutil.ReadFile(ctrdStdioFilePath)
+	stdioContents, err := os.ReadFile(ctrdStdioFilePath)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1963,7 +1962,7 @@ func TestContainerNoSTDIN(t *testing.T) {
 	}
 	defer container.Delete(ctx, WithSnapshotCleanup)
 
-	task, err := container.NewTask(ctx, cio.NewCreator(cio.WithStreams(nil, ioutil.Discard, ioutil.Discard)))
+	task, err := container.NewTask(ctx, cio.NewCreator(cio.WithStreams(nil, io.Discard, io.Discard)))
 	if err != nil {
 		t.Fatal(err)
 	}

integration/client/container_test.go

@@ -20,7 +20,6 @@ import (
 	"bytes"
 	"context"
 	"io"
-	"io/ioutil"
 	"os"
 	"path"
 	"runtime"
@@ -231,7 +230,7 @@ func TestContainerOutput(t *testing.T) {
 }
 
 func withByteBuffers(stdout io.Writer) cio.Opt {
-	// TODO: could this use ioutil.Discard?
+	// TODO: could this use io.Discard?
 	return func(streams *cio.Streams) {
 		streams.Stdin = new(bytes.Buffer)
 		streams.Stdout = stdout
@@ -515,7 +514,7 @@ func TestContainerCloseIO(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	task, err := container.NewTask(ctx, cio.NewCreator(cio.WithStreams(r, stdout, ioutil.Discard)))
+	task, err := container.NewTask(ctx, cio.NewCreator(cio.WithStreams(r, stdout, io.Discard)))
 	if err != nil {
 		t.Fatal(err)
 	}

integration/client/daemon_config_linux_test.go

@@ -21,7 +21,6 @@ import (
 	"bytes"
 	"context"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -52,7 +51,7 @@ func newDaemonWithConfig(t *testing.T, configTOML string) (*Client, *daemon, fun
 		buf               = bytes.NewBuffer(nil)
 	)
 
-	tempDir, err := ioutil.TempDir("", "containerd-test-new-daemon-with-config")
+	tempDir, err := os.MkdirTemp("", "containerd-test-new-daemon-with-config")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -63,7 +62,7 @@ func newDaemonWithConfig(t *testing.T, configTOML string) (*Client, *daemon, fun
 	}()
 
 	configTOMLFile := filepath.Join(tempDir, "config.toml")
-	if err = ioutil.WriteFile(configTOMLFile, []byte(configTOML), 0600); err != nil {
+	if err = os.WriteFile(configTOMLFile, []byte(configTOML), 0600); err != nil {
 		t.Fatal(err)
 	}
 
@@ -119,7 +118,7 @@ func newDaemonWithConfig(t *testing.T, configTOML string) (*Client, *daemon, fun
 
 // TestDaemonRuntimeRoot ensures plugin.linux.runtime_root is not ignored
 func TestDaemonRuntimeRoot(t *testing.T) {
-	runtimeRoot, err := ioutil.TempDir("", "containerd-test-runtime-root")
+	runtimeRoot, err := os.MkdirTemp("", "containerd-test-runtime-root")
 	if err != nil {
 		t.Fatal(err)
 	}

integration/client/import_test.go

@@ -22,7 +22,6 @@ import (
 	"encoding/json"
 	"io"
 
-	"io/ioutil"
 	"math/rand"
 	"reflect"
 	"testing"
@@ -285,7 +284,7 @@ func checkImages(t *testing.T, target digest.Digest, actual []images.Image, name
 }
 
 func createContent(size int64, seed int64) ([]byte, digest.Digest) {
-	b, err := ioutil.ReadAll(io.LimitReader(rand.New(rand.NewSource(seed)), size))
+	b, err := io.ReadAll(io.LimitReader(rand.New(rand.NewSource(seed)), size))
 	if err != nil {
 		panic(err)
 	}