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

cmd/devp2p/dnscmd.go

@@ -20,7 +20,6 @@ import (
 	"crypto/ecdsa"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"time"
@@ -253,7 +252,7 @@ func dnsNukeRoute53(ctx *cli.Context) error {
 
 // loadSigningKey loads a private key in Ethereum keystore format.
 func loadSigningKey(keyfile string) *ecdsa.PrivateKey {
-	keyjson, err := ioutil.ReadFile(keyfile)
+	keyjson, err := os.ReadFile(keyfile)
 	if err != nil {
 		exit(fmt.Errorf("failed to read the keyfile at '%s': %v", keyfile, err))
 	}
@@ -382,7 +381,7 @@ func writeTreeMetadata(directory string, def *dnsDefinition) {
 		exit(err)
 	}
 	metaFile, _ := treeDefinitionFiles(directory)
-	if err := ioutil.WriteFile(metaFile, metaJSON, 0644); err != nil {
+	if err := os.WriteFile(metaFile, metaJSON, 0644); err != nil {
 		exit(err)
 	}
 }
@@ -411,7 +410,7 @@ func writeTXTJSON(file string, txt map[string]string) {
 		fmt.Println()
 		return
 	}
-	if err := ioutil.WriteFile(file, txtJSON, 0644); err != nil {
+	if err := os.WriteFile(file, txtJSON, 0644); err != nil {
 		exit(err)
 	}
 }

cmd/devp2p/enrcmd.go

@@ -22,7 +22,6 @@ import (
 	"encoding/hex"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net"
 	"os"
 	"strconv"
@@ -54,9 +53,9 @@ func enrdump(ctx *cli.Context) error {
 		var b []byte
 		var err error
 		if file == "-" {
-			b, err = ioutil.ReadAll(os.Stdin)
+			b, err = io.ReadAll(os.Stdin)
 		} else {
-			b, err = ioutil.ReadFile(file)
+			b, err = os.ReadFile(file)
 		}
 		if err != nil {
 			return err

cmd/devp2p/internal/ethtest/chain.go

@@ -21,7 +21,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"math/big"
 	"os"
 	"strings"
@@ -153,7 +152,7 @@ func loadChain(chainfile string, genesis string) (*Chain, error) {
 }
 
 func loadGenesis(genesisFile string) (core.Genesis, error) {
-	chainConfig, err := ioutil.ReadFile(genesisFile)
+	chainConfig, err := os.ReadFile(genesisFile)
 	if err != nil {
 		return core.Genesis{}, err
 	}

cmd/devp2p/nodeset.go

@@ -20,7 +20,6 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"sort"
 	"time"
@@ -66,7 +65,7 @@ func writeNodesJSON(file string, nodes nodeSet) {
 		os.Stdout.Write(nodesJSON)
 		return
 	}
-	if err := ioutil.WriteFile(file, nodesJSON, 0644); err != nil {
+	if err := os.WriteFile(file, nodesJSON, 0644); err != nil {
 		exit(err)
 	}
 }