all: replace uses of ioutil with io and os (#24869)

cmd/geth/accountcmd.go

@@ -18,7 +18,7 @@ package main
 
 import (
 	"fmt"
-	"io/ioutil"
+	"os"
 
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/accounts/keystore"
@@ -320,7 +320,7 @@ func importWallet(ctx *cli.Context) error {
 	if len(keyfile) == 0 {
 		utils.Fatalf("keyfile must be given as argument")
 	}
-	keyJSON, err := ioutil.ReadFile(keyfile)
+	keyJSON, err := os.ReadFile(keyfile)
 	if err != nil {
 		utils.Fatalf("Could not read wallet file: %v", err)
 	}

cmd/geth/accountcmd_test.go

@@ -18,6 +18,7 @@ package main
 
 import (
 	"io/ioutil"
+	"os"
 	"path/filepath"
 	"runtime"
 	"strings"
@@ -113,11 +114,11 @@ func TestAccountImport(t *testing.T) {
 func importAccountWithExpect(t *testing.T, key string, expected string) {
 	dir := t.TempDir()
 	keyfile := filepath.Join(dir, "key.prv")
-	if err := ioutil.WriteFile(keyfile, []byte(key), 0600); err != nil {
+	if err := os.WriteFile(keyfile, []byte(key), 0600); err != nil {
 		t.Error(err)
 	}
 	passwordFile := filepath.Join(dir, "password.txt")
-	if err := ioutil.WriteFile(passwordFile, []byte("foobar"), 0600); err != nil {
+	if err := os.WriteFile(passwordFile, []byte("foobar"), 0600); err != nil {
 		t.Error(err)
 	}
 	geth := runGeth(t, "--lightkdf", "account", "import", keyfile, "-password", passwordFile)

cmd/geth/dao_test.go

@@ -17,8 +17,8 @@
 package main
 
 import (
-	"io/ioutil"
 	"math/big"
+	"os"
 	"path/filepath"
 	"testing"
 
@@ -110,7 +110,7 @@ func testDAOForkBlockNewChain(t *testing.T, test int, genesis string, expectBloc
 	// Start a Geth instance with the requested flags set and immediately terminate
 	if genesis != "" {
 		json := filepath.Join(datadir, "genesis.json")
-		if err := ioutil.WriteFile(json, []byte(genesis), 0600); err != nil {
+		if err := os.WriteFile(json, []byte(genesis), 0600); err != nil {
 			t.Fatalf("test %d: failed to write genesis file: %v", test, err)
 		}
 		runGeth(t, "--datadir", datadir, "--networkid", "1337", "init", json).WaitExit()

cmd/geth/genesis_test.go

@@ -17,7 +17,7 @@
 package main
 
 import (
-	"io/ioutil"
+	"os"
 	"path/filepath"
 	"testing"
 )
@@ -76,7 +76,7 @@ func TestCustomGenesis(t *testing.T) {
 
 		// Initialize the data directory with the custom genesis block
 		json := filepath.Join(datadir, "genesis.json")
-		if err := ioutil.WriteFile(json, []byte(tt.genesis), 0600); err != nil {
+		if err := os.WriteFile(json, []byte(tt.genesis), 0600); err != nil {
 			t.Fatalf("test %d: failed to write genesis file: %v", i, err)
 		}
 		runGeth(t, "--datadir", datadir, "init", json).WaitExit()

cmd/geth/version_check.go

@@ -20,8 +20,9 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
+	"os"
 	"regexp"
 	"strings"
 
@@ -112,14 +113,14 @@ func checkCurrent(url, current string) error {
 // fetch makes an HTTP request to the given url and returns the response body
 func fetch(url string) ([]byte, error) {
 	if filep := strings.TrimPrefix(url, "file://"); filep != url {
-		return ioutil.ReadFile(filep)
+		return os.ReadFile(filep)
 	}
 	res, err := http.Get(url)
 	if err != nil {
 		return nil, err
 	}
 	defer res.Body.Close()
-	body, err := ioutil.ReadAll(res.Body)
+	body, err := io.ReadAll(res.Body)
 	if err != nil {
 		return nil, err
 	}

cmd/geth/version_check_test.go

@@ -20,6 +20,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
+	"os"
 	"path/filepath"
 	"regexp"
 	"strconv"
@@ -49,7 +50,7 @@ func TestVerification(t *testing.T) {
 
 func testVerification(t *testing.T, pubkey, sigdir string) {
 	// Data to verify
-	data, err := ioutil.ReadFile("./testdata/vcheck/data.json")
+	data, err := os.ReadFile("./testdata/vcheck/data.json")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -59,7 +60,7 @@ func testVerification(t *testing.T, pubkey, sigdir string) {
 		t.Fatal(err)
 	}
 	for _, f := range files {
-		sig, err := ioutil.ReadFile(filepath.Join(sigdir, f.Name()))
+		sig, err := os.ReadFile(filepath.Join(sigdir, f.Name()))
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -87,7 +88,7 @@ func versionUint(v string) int {
 
 // TestMatching can be used to check that the regexps are correct
 func TestMatching(t *testing.T) {
-	data, _ := ioutil.ReadFile("./testdata/vcheck/vulnerabilities.json")
+	data, _ := os.ReadFile("./testdata/vcheck/vulnerabilities.json")
 	var vulns []vulnJson
 	if err := json.Unmarshal(data, &vulns); err != nil {
 		t.Fatal(err)