refactor: move from io/ioutil to io and os packages

The io/ioutil package has been deprecated as of Go 1.16 [1]. This commit
replaces the existing io/ioutil functions with their new definitions in
io and os packages.

Reference: https://golang.org/doc/go1.16#ioutil
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

tempfork/gliderlabs/ssh/agent.go

@@ -2,8 +2,8 @@ package ssh
 
 import (
 	"io"
-	"io/ioutil"
 	"net"
+	"os"
 	"path"
 	"sync"
 
@@ -36,7 +36,7 @@ func AgentRequested(sess Session) bool {
 // NewAgentListener sets up a temporary Unix socket that can be communicated
 // to the session environment and used for forwarding connections.
 func NewAgentListener() (net.Listener, error) {
-	dir, err := ioutil.TempDir("", agentTempDir)
+	dir, err := os.MkdirTemp("", agentTempDir)
 	if err != nil {
 		return nil, err
 	}

tempfork/gliderlabs/ssh/example_test.go

@@ -3,7 +3,7 @@ package ssh_test
 import (
 	"errors"
 	"io"
-	"io/ioutil"
+	"os"
 
 	"tailscale.com/tempfork/gliderlabs/ssh"
 )
@@ -29,7 +29,7 @@ func ExampleNoPty() {
 func ExamplePublicKeyAuth() {
 	ssh.ListenAndServe(":2222", nil,
 		ssh.PublicKeyAuth(func(ctx ssh.Context, key ssh.PublicKey) error {
-			data, err := ioutil.ReadFile("/path/to/allowed/key.pub")
+			data, err := os.ReadFile("/path/to/allowed/key.pub")
 			if err != nil {
 				return err
 			}

tempfork/gliderlabs/ssh/options.go

@@ -1,7 +1,7 @@
 package ssh
 
 import (
-	"io/ioutil"
+	"os"
 
 	gossh "github.com/tailscale/golang-x-crypto/ssh"
 )
@@ -26,7 +26,7 @@ func PublicKeyAuth(fn PublicKeyHandler) Option {
 // from a PEM file at filepath.
 func HostKeyFile(filepath string) Option {
 	return func(srv *Server) error {
-		pemBytes, err := ioutil.ReadFile(filepath)
+		pemBytes, err := os.ReadFile(filepath)
 		if err != nil {
 			return err
 		}

tempfork/gliderlabs/ssh/tcpip_test.go

@@ -5,7 +5,6 @@ package ssh
 
 import (
 	"bytes"
-	"io/ioutil"
 	"net"
 	"strconv"
 	"strings"
@@ -61,7 +60,7 @@ func TestLocalPortForwardingWorks(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Error connecting to %v: %v", l.Addr().String(), err)
 	}
-	result, err := ioutil.ReadAll(conn)
+	result, err := io.ReadAll(conn)
 	if err != nil {
 		t.Fatal(err)
 	}