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

cmd/puppeth/genesis_test.go

@@ -19,7 +19,7 @@ package main
 import (
 	"bytes"
 	"encoding/json"
-	"io/ioutil"
+	"os"
 	"reflect"
 	"strings"
 	"testing"
@@ -30,7 +30,7 @@ import (
 
 // Tests the go-ethereum to Aleth chainspec conversion for the Stureby testnet.
 func TestAlethSturebyConverter(t *testing.T) {
-	blob, err := ioutil.ReadFile("testdata/stureby_geth.json")
+	blob, err := os.ReadFile("testdata/stureby_geth.json")
 	if err != nil {
 		t.Fatalf("could not read file: %v", err)
 	}
@@ -43,7 +43,7 @@ func TestAlethSturebyConverter(t *testing.T) {
 		t.Fatalf("failed creating chainspec: %v", err)
 	}
 
-	expBlob, err := ioutil.ReadFile("testdata/stureby_aleth.json")
+	expBlob, err := os.ReadFile("testdata/stureby_aleth.json")
 	if err != nil {
 		t.Fatalf("could not read file: %v", err)
 	}
@@ -69,7 +69,7 @@ func TestAlethSturebyConverter(t *testing.T) {
 
 // Tests the go-ethereum to Parity chainspec conversion for the Stureby testnet.
 func TestParitySturebyConverter(t *testing.T) {
-	blob, err := ioutil.ReadFile("testdata/stureby_geth.json")
+	blob, err := os.ReadFile("testdata/stureby_geth.json")
 	if err != nil {
 		t.Fatalf("could not read file: %v", err)
 	}
@@ -85,7 +85,7 @@ func TestParitySturebyConverter(t *testing.T) {
 	if err != nil {
 		t.Fatalf("failed encoding chainspec: %v", err)
 	}
-	expBlob, err := ioutil.ReadFile("testdata/stureby_parity.json")
+	expBlob, err := os.ReadFile("testdata/stureby_parity.json")
 	if err != nil {
 		t.Fatalf("could not read file: %v", err)
 	}

cmd/puppeth/ssh.go

@@ -21,7 +21,6 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"net"
 	"os"
 	"os/user"
@@ -96,7 +95,7 @@ func dial(server string, pubkey []byte) (*sshClient, error) {
 	}
 	if err != nil {
 		path := filepath.Join(user.HomeDir, ".ssh", identity)
-		if buf, err := ioutil.ReadFile(path); err != nil {
+		if buf, err := os.ReadFile(path); err != nil {
 			log.Warn("No SSH key, falling back to passwords", "path", path, "err", err)
 		} else {
 			key, err := ssh.ParsePrivateKey(buf)

cmd/puppeth/wizard.go

@@ -19,7 +19,6 @@ package main
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"math/big"
 	"net"
 	"net/url"
@@ -65,7 +64,7 @@ func (c config) flush() {
 	os.MkdirAll(filepath.Dir(c.path), 0755)
 
 	out, _ := json.MarshalIndent(c, "", "  ")
-	if err := ioutil.WriteFile(c.path, out, 0644); err != nil {
+	if err := os.WriteFile(c.path, out, 0644); err != nil {
 		log.Warn("Failed to save puppeth configs", "file", c.path, "err", err)
 	}
 }

cmd/puppeth/wizard_genesis.go

@@ -21,7 +21,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"math/big"
 	"math/rand"
 	"net/http"
@@ -263,7 +262,7 @@ func (w *wizard) manageGenesis() {
 
 		// Export the native genesis spec used by puppeth and Geth
 		gethJson := filepath.Join(folder, fmt.Sprintf("%s.json", w.network))
-		if err := ioutil.WriteFile(gethJson, out, 0644); err != nil {
+		if err := os.WriteFile(gethJson, out, 0644); err != nil {
 			log.Error("Failed to save genesis file", "err", err)
 			return
 		}
@@ -305,7 +304,7 @@ func saveGenesis(folder, network, client string, spec interface{}) {
 	path := filepath.Join(folder, fmt.Sprintf("%s-%s.json", network, client))
 
 	out, _ := json.MarshalIndent(spec, "", "  ")
-	if err := ioutil.WriteFile(path, out, 0644); err != nil {
+	if err := os.WriteFile(path, out, 0644); err != nil {
 		log.Error("Failed to save genesis file", "client", client, "err", err)
 		return
 	}

cmd/puppeth/wizard_intro.go

@@ -19,7 +19,6 @@ package main
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -73,7 +72,7 @@ func (w *wizard) run() {
 	// Load initial configurations and connect to all live servers
 	w.conf.path = filepath.Join(os.Getenv("HOME"), ".puppeth", w.network)
 
-	blob, err := ioutil.ReadFile(w.conf.path)
+	blob, err := os.ReadFile(w.conf.path)
 	if err != nil {
 		log.Warn("No previous configurations found", "path", w.conf.path)
 	} else if err := json.Unmarshal(blob, &w.conf); err != nil {