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>

contrib/fuzz/archive_fuzzer.go

@@ -18,7 +18,6 @@ package fuzz
 import (
 	"bytes"
 	"context"
-	"io/ioutil"
 	"os"
 
 	fuzz "github.com/AdaLogics/go-fuzz-headers"
@@ -37,7 +36,7 @@ func FuzzApply(data []byte) int {
 		return 0
 	}
 	maxIters := 20
-	tmpDir, err := ioutil.TempDir("", "prefix-test")
+	tmpDir, err := os.MkdirTemp("", "prefix-test")
 	if err != nil {
 		return 0
 	}
@@ -63,7 +62,7 @@ func FuzzImportIndex(data []byte) int {
 	}
 	ctx := context.Background()
 	r := bytes.NewReader(tarBytes)
-	tmpdir, err := ioutil.TempDir("", "fuzzing-")
+	tmpdir, err := os.MkdirTemp("", "fuzzing-")
 	if err != nil {
 		return 0
 	}

contrib/fuzz/container_fuzzer.go

@@ -27,7 +27,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"os"
 	"strings"
@@ -148,7 +147,7 @@ func checkIfShouldRestart(err error) {
 // startDaemon() starts the daemon.
 func startDaemon(ctx context.Context, shouldTearDown bool) {
 	buf := bytes.NewBuffer(nil)
-	stdioFile, err := ioutil.TempFile("", "")
+	stdioFile, err := os.CreateTemp("", "")
 	if err != nil {
 		// We panic here as it is a fuzz-blocker that
 		// may need fixing

contrib/fuzz/content_fuzzer.go

@@ -21,7 +21,6 @@ import (
 	"context"
 	_ "crypto/sha256" // required by go-digest
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -101,7 +100,7 @@ func FuzzCSWalk(data []byte) int {
 	ctx := context.Background()
 	expected := map[digest.Digest]struct{}{}
 	found := map[digest.Digest]struct{}{}
-	tmpdir, err := ioutil.TempDir("", "fuzzing-")
+	tmpdir, err := os.MkdirTemp("", "fuzzing-")
 	if err != nil {
 		return 0
 	}
@@ -145,7 +144,7 @@ func FuzzArchiveExport(data []byte) int {
 		return 0
 	}
 	ctx := context.Background()
-	tmpdir, err := ioutil.TempDir("", "fuzzing-")
+	tmpdir, err := os.MkdirTemp("", "fuzzing-")
 	if err != nil {
 		return 0
 	}

contrib/fuzz/docker_fuzzer.go

@@ -25,7 +25,7 @@ package docker
 import (
 	"context"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -67,7 +67,7 @@ func FuzzFetcher(data []byte) int {
 	if err != nil {
 		return 0
 	}
-	b, err := ioutil.ReadAll(rc)
+	b, err := io.ReadAll(rc)
 	if err != nil {
 		return 0
 	}