all: Remove usage of deprecated io/ioutil (#7971)

As of Go 1.16 io/ioutil is deprecated. This replaces usage with the
corresponding functions in package os and package io.

lib/model/folder_sendrecv_test.go

@@ -13,7 +13,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -680,8 +679,8 @@ func TestIssue3164(t *testing.T) {
 	ignDir := filepath.Join("issue3164", "oktodelete")
 	subDir := filepath.Join(ignDir, "foobar")
 	must(t, ffs.MkdirAll(subDir, 0777))
-	must(t, ioutil.WriteFile(filepath.Join(tmpDir, subDir, "file"), []byte("Hello"), 0644))
-	must(t, ioutil.WriteFile(filepath.Join(tmpDir, ignDir, "file"), []byte("Hello"), 0644))
+	must(t, os.WriteFile(filepath.Join(tmpDir, subDir, "file"), []byte("Hello"), 0644))
+	must(t, os.WriteFile(filepath.Join(tmpDir, ignDir, "file"), []byte("Hello"), 0644))
 	file := protocol.FileInfo{
 		Name: "issue3164",
 	}

lib/model/model_test.go

@@ -12,7 +12,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"math/rand"
 	"os"
 	"path/filepath"
@@ -2152,7 +2151,7 @@ func TestIssue2782(t *testing.T) {
 	if err := os.MkdirAll(testDir+"/syncdir", 0755); err != nil {
 		t.Skip(err)
 	}
-	if err := ioutil.WriteFile(testDir+"/syncdir/file", []byte("hello, world\n"), 0644); err != nil {
+	if err := os.WriteFile(testDir+"/syncdir/file", []byte("hello, world\n"), 0644); err != nil {
 		t.Skip(err)
 	}
 	if err := os.Symlink("syncdir", testDir+"/synclink"); err != nil {
@@ -2763,7 +2762,7 @@ func TestVersionRestore(t *testing.T) {
 	// In each file, we write the filename as the content
 	// We verify that the content matches at the expected filenames
 	// after the restore operation.
-	dir, err := ioutil.TempDir("", "")
+	dir, err := os.MkdirTemp("", "")
 	must(t, err)
 	defer os.RemoveAll(dir)
 
@@ -2900,7 +2899,7 @@ func TestVersionRestore(t *testing.T) {
 		}
 		defer fd.Close()
 
-		content, err := ioutil.ReadAll(fd)
+		content, err := io.ReadAll(fd)
 		if err != nil {
 			t.Error(err)
 		}
@@ -2930,7 +2929,7 @@ func TestVersionRestore(t *testing.T) {
 				must(t, err)
 				defer fd.Close()
 
-				content, err := ioutil.ReadAll(fd)
+				content, err := io.ReadAll(fd)
 				if err != nil {
 					t.Error(err)
 				}

lib/model/requests_test.go

@@ -10,7 +10,6 @@ import (
 	"bytes"
 	"context"
 	"errors"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -236,7 +235,7 @@ func TestRequestVersioningSymlinkAttack(t *testing.T) {
 
 	// Create a temporary directory that we will use as target to see if
 	// we can escape to it
-	tmpdir, err := ioutil.TempDir("", "syncthing-test")
+	tmpdir, err := os.MkdirTemp("", "syncthing-test")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -681,7 +680,7 @@ func TestRequestSymlinkWindows(t *testing.T) {
 }
 
 func equalContents(path string, contents []byte) error {
-	if bs, err := ioutil.ReadFile(path); err != nil {
+	if bs, err := os.ReadFile(path); err != nil {
 		return err
 	} else if !bytes.Equal(bs, contents) {
 		return errors.New("incorrect data")

lib/model/testutils_test.go

@@ -8,7 +8,6 @@ package model
 
 import (
 	"context"
-	"io/ioutil"
 	"os"
 	"testing"
 	"time"
@@ -76,7 +75,7 @@ func init() {
 }
 
 func createTmpWrapper(cfg config.Configuration) (config.Wrapper, context.CancelFunc) {
-	tmpFile, err := ioutil.TempFile("", "syncthing-testConfig-")
+	tmpFile, err := os.CreateTemp("", "syncthing-testConfig-")
 	if err != nil {
 		panic(err)
 	}
@@ -215,7 +214,7 @@ func cleanupModelAndRemoveDir(m *testModel, dir string) {
 }
 
 func createTmpDir() string {
-	tmpDir, err := ioutil.TempDir("", "syncthing_testFolder-")
+	tmpDir, err := os.MkdirTemp("", "syncthing_testFolder-")
 	if err != nil {
 		panic("Failed to create temporary testing dir")
 	}