build: Bump quic-go to 0.24.0

This way, we don't need a second loop over the Availabilities to remove
the selected item.

build.go

@@ -20,7 +20,6 @@ import (
 	"flag"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -723,7 +722,7 @@ func shouldBuildSyso(dir string) (string, error) {
 	}
 
 	jsonPath := filepath.Join(dir, "versioninfo.json")
-	err = ioutil.WriteFile(jsonPath, bs, 0644)
+	err = os.WriteFile(jsonPath, bs, 0644)
 	if err != nil {
 		return "", errors.New("failed to create " + jsonPath + ": " + err.Error())
 	}
@@ -762,12 +761,12 @@ func shouldCleanupSyso(sysoFilePath string) {
 // exists. The permission bits are copied as well. If dst already exists and
 // the contents are identical to src the modification time is not updated.
 func copyFile(src, dst string, perm os.FileMode) error {
-	in, err := ioutil.ReadFile(src)
+	in, err := os.ReadFile(src)
 	if err != nil {
 		return err
 	}
 
-	out, err := ioutil.ReadFile(dst)
+	out, err := os.ReadFile(dst)
 	if err != nil {
 		// The destination probably doesn't exist, we should create
 		// it.
@@ -783,7 +782,7 @@ func copyFile(src, dst string, perm os.FileMode) error {
 
 copy:
 	os.MkdirAll(filepath.Dir(dst), 0777)
-	if err := ioutil.WriteFile(dst, in, perm); err != nil {
+	if err := os.WriteFile(dst, in, perm); err != nil {
 		return err
 	}
 
@@ -958,7 +957,7 @@ func rmr(paths ...string) {
 }
 
 func getReleaseVersion() (string, error) {
-	bs, err := ioutil.ReadFile("RELEASE")
+	bs, err := os.ReadFile("RELEASE")
 	if err != nil {
 		return "", err
 	}
@@ -1290,11 +1289,11 @@ func zipFile(out string, files []archiveFile) {
 
 		if strings.HasSuffix(f.dst, ".txt") {
 			// Text file. Read it and convert line endings.
-			bs, err := ioutil.ReadAll(sf)
+			bs, err := io.ReadAll(sf)
 			if err != nil {
 				log.Fatal(err)
 			}
-			bs = bytes.Replace(bs, []byte{'\n'}, []byte{'\n', '\r'}, -1)
+			bs = bytes.Replace(bs, []byte{'\n'}, []byte{'\r', '\n'}, -1)
 			fh.UncompressedSize = uint32(len(bs))
 			fh.UncompressedSize64 = uint64(len(bs))
 

cmd/stcrashreceiver/main.go

@@ -17,7 +17,6 @@ import (
 	"flag"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"net/http"
 	"os"
@@ -58,7 +57,7 @@ func main() {
 func handleFailureFn(dsn, failureDir string) func(w http.ResponseWriter, req *http.Request) {
 	return func(w http.ResponseWriter, req *http.Request) {
 		lr := io.LimitReader(req.Body, maxRequestSize)
-		bs, err := ioutil.ReadAll(lr)
+		bs, err := io.ReadAll(lr)
 		req.Body.Close()
 		if err != nil {
 			http.Error(w, err.Error(), 500)

cmd/stcrashreceiver/sentry.go

@@ -9,7 +9,7 @@ package main
 import (
 	"bytes"
 	"errors"
-	"io/ioutil"
+	"io"
 	"regexp"
 	"strings"
 	"sync"
@@ -93,7 +93,7 @@ func parseCrashReport(path string, report []byte) (*raven.Packet, error) {
 	}
 
 	r := bytes.NewReader(report)
-	ctx, err := stack.ParseDump(r, ioutil.Discard, false)
+	ctx, err := stack.ParseDump(r, io.Discard, false)
 	if err != nil {
 		return nil, err
 	}

cmd/stcrashreceiver/sentry_test.go

@@ -8,7 +8,7 @@ package main
 
 import (
 	"fmt"
-	"io/ioutil"
+	"os"
 	"testing"
 )
 
@@ -59,7 +59,7 @@ func TestParseVersion(t *testing.T) {
 }
 
 func TestParseReport(t *testing.T) {
-	bs, err := ioutil.ReadFile("_testdata/panic.log")
+	bs, err := os.ReadFile("_testdata/panic.log")
 	if err != nil {
 		t.Fatal(err)
 	}

cmd/stcrashreceiver/sourcecodeloader.go

@@ -9,7 +9,7 @@ package main
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"path/filepath"
 	"strings"
@@ -80,7 +80,7 @@ func (l *githubSourceCodeLoader) Load(filename string, line, context int) ([][]b
 			fmt.Println("Loading source:", resp.Status)
 			return nil, 0
 		}
-		data, err := ioutil.ReadAll(resp.Body)
+		data, err := io.ReadAll(resp.Body)
 		_ = resp.Body.Close()
 		if err != nil {
 			fmt.Println("Loading source:", err.Error())

cmd/stcrashreceiver/stcrashreceiver.go

@@ -10,7 +10,6 @@ import (
 	"bytes"
 	"compress/gzip"
 	"io"
-	"io/ioutil"
 	"log"
 	"net/http"
 	"os"
@@ -96,7 +95,7 @@ func (r *crashReceiver) servePut(reportID, fullPath string, w http.ResponseWrite
 	// Read at most maxRequestSize of report data.
 	log.Println("Receiving report", reportID)
 	lr := io.LimitReader(req.Body, maxRequestSize)
-	bs, err := ioutil.ReadAll(lr)
+	bs, err := io.ReadAll(lr)
 	if err != nil {
 		log.Println("Reading report:", err)
 		http.Error(w, "Internal server error", http.StatusInternalServerError)
@@ -110,7 +109,7 @@ func (r *crashReceiver) servePut(reportID, fullPath string, w http.ResponseWrite
 	gw.Close()
 
 	// Create an output file with the compressed report
-	err = ioutil.WriteFile(fullPath, buf.Bytes(), 0644)
+	err = os.WriteFile(fullPath, buf.Bytes(), 0644)
 	if err != nil {
 		log.Println("Saving report:", err)
 		http.Error(w, "Internal server error", http.StatusInternalServerError)

cmd/stcrashreceiver/util.go

@@ -10,9 +10,9 @@ import (
 	"bytes"
 	"compress/gzip"
 	"fmt"
-	"io/ioutil"
 	"net"
 	"net/http"
+	"os"
 	"path/filepath"
 	"time"
 
@@ -53,5 +53,5 @@ func compressAndWrite(bs []byte, fullPath string) error {
 	gw.Close()
 
 	// Create an output file with the compressed report
-	return ioutil.WriteFile(fullPath, buf.Bytes(), 0644)
+	return os.WriteFile(fullPath, buf.Bytes(), 0644)
 }

cmd/stdiscosrv/apisrv.go

@@ -419,7 +419,7 @@ func fixupAddresses(remote *net.TCPAddr, addresses []string) []string {
 
 			// If zero port was specified, use remote port.
 			if port == "0" && remote.Port > 0 {
-				port = fmt.Sprintf("%d", remote.Port)
+				port = strconv.Itoa(remote.Port)
 			}
 		}
 

cmd/strelaypoolsrv/main.go

@@ -11,7 +11,6 @@ import (
 	"flag"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"net"
 	"net/http"
@@ -560,7 +559,7 @@ func limit(addr string, cache *lru.Cache, lock sync.Mutex, intv time.Duration, b
 }
 
 func loadRelays(file string) []*relay {
-	content, err := ioutil.ReadFile(file)
+	content, err := os.ReadFile(file)
 	if err != nil {
 		log.Println("Failed to load relays: " + err.Error())
 		return nil
@@ -598,11 +597,11 @@ func saveRelays(file string, relays []*relay) error {
 	for _, relay := range relays {
 		content += relay.uri.String() + "\n"
 	}
-	return ioutil.WriteFile(file, []byte(content), 0777)
+	return os.WriteFile(file, []byte(content), 0777)
 }
 
 func createTestCertificate() tls.Certificate {
-	tmpDir, err := ioutil.TempDir("", "relaypoolsrv")
+	tmpDir, err := os.MkdirTemp("", "relaypoolsrv")
 	if err != nil {
 		log.Fatal(err)
 	}

cmd/strelaysrv/main.go

@@ -200,7 +200,7 @@ func main() {
 		go natSvc.Serve(ctx)
 		defer cancel()
 		found := make(chan struct{})
-		mapping.OnChanged(func(_ *nat.Mapping, _, _ []nat.Address) {
+		mapping.OnChanged(func() {
 			select {
 			case found <- struct{}{}:
 			default:

cmd/strelaysrv/pool.go

@@ -6,7 +6,7 @@ import (
 	"bytes"
 	"crypto/tls"
 	"encoding/json"
-	"io/ioutil"
+	"io"
 	"log"
 	"net/http"
 	"net/url"
@@ -56,7 +56,7 @@ func poolHandler(pool string, uri *url.URL, mapping mapping, ownCert tls.Certifi
 			continue
 		}
 
-		bs, err := ioutil.ReadAll(resp.Body)
+		bs, err := io.ReadAll(resp.Body)
 		resp.Body.Close()
 		if err != nil {
 			log.Printf("Error joining pool %v: reading response: %v", pool, err)

cmd/stsigtool/main.go

@@ -9,7 +9,6 @@ package main
 import (
 	"flag"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 
@@ -69,7 +68,7 @@ func gen() {
 }
 
 func sign(keyname, dataname string) {
-	privkey, err := ioutil.ReadFile(keyname)
+	privkey, err := os.ReadFile(keyname)
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -95,7 +94,7 @@ func sign(keyname, dataname string) {
 }
 
 func verifyWithFile(signame, dataname, keyname string) {
-	pubkey, err := ioutil.ReadFile(keyname)
+	pubkey, err := os.ReadFile(keyname)
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -103,7 +102,7 @@ func verifyWithFile(signame, dataname, keyname string) {
 }
 
 func verifyWithKey(signame, dataname string, pubkey []byte) {
-	sig, err := ioutil.ReadFile(signame)
+	sig, err := os.ReadFile(signame)
 	if err != nil {
 		log.Fatal(err)
 	}

cmd/syncthing/cli/main.go

@@ -9,7 +9,7 @@ package cli
 import (
 	"bufio"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"os"
 	"strings"
 
@@ -151,7 +151,7 @@ func parseFlags(c *preCli) error {
 		}
 	}
 	// We don't want kong to print anything nor os.Exit (e.g. on -h)
-	parser, err := kong.New(c, kong.Writers(ioutil.Discard, ioutil.Discard), kong.Exit(func(int) {}))
+	parser, err := kong.New(c, kong.Writers(io.Discard, io.Discard), kong.Exit(func(int) {}))
 	if err != nil {
 		return err
 	}

cmd/syncthing/cli/pending.go

@@ -0,0 +1,29 @@
+// Copyright (C) 2021 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package cli
+
+import (
+	"github.com/urfave/cli"
+)
+
+var pendingCommand = cli.Command{
+	Name:     "pending",
+	HideHelp: true,
+	Usage:    "Pending subcommand group",
+	Subcommands: []cli.Command{
+		{
+			Name:   "devices",
+			Usage:  "Show pending devices",
+			Action: expects(0, indexDumpOutput("cluster/pending/devices")),
+		},
+		{
+			Name:   "folders",
+			Usage:  "Show pending folders",
+			Action: expects(0, indexDumpOutput("cluster/pending/folders")),
+		},
+	},
+}

cmd/syncthing/cli/show.go

@@ -35,6 +35,7 @@ var showCommand = cli.Command{
 			Usage:  "Report about connections to other devices",
 			Action: expects(0, indexDumpOutput("system/connections")),
 		},
+		pendingCommand,
 		{
 			Name:   "usage",
 			Usage:  "Show usage report",

cmd/syncthing/cli/utils.go

@@ -10,7 +10,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"mime"
 	"net/http"
 	"os"
@@ -23,7 +23,7 @@ import (
 )
 
 func responseToBArray(response *http.Response) ([]byte, error) {
-	bytes, err := ioutil.ReadAll(response.Body)
+	bytes, err := io.ReadAll(response.Body)
 	if err != nil {
 		return nil, err
 	}

cmd/syncthing/cmdutil/options_common.go

@@ -0,0 +1,15 @@
+// Copyright (C) 2021 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package cmdutil
+
+// CommonOptions are reused among several subcommands
+type CommonOptions struct {
+	buildCommonOptions
+	ConfDir         string `name:"config" placeholder:"PATH" help:"Set configuration directory (config and keys)"`
+	HomeDir         string `name:"home" placeholder:"PATH" help:"Set configuration and data directory"`
+	NoDefaultFolder bool   `env:"STNODEFAULTFOLDER" help:"Don't create the \"default\" folder on first startup"`
+}

cmd/syncthing/cmdutil/options_others.go

@@ -7,8 +7,8 @@
 //go:build !windows
 // +build !windows
 
-package main
+package cmdutil
 
-type buildServeOptions struct {
+type buildCommonOptions struct {
 	HideConsole bool `hidden:""`
 }

cmd/syncthing/cmdutil/options_windows.go

@@ -4,8 +4,8 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this file,
 // You can obtain one at https://mozilla.org/MPL/2.0/.
 
-package main
+package cmdutil
 
-type buildServeOptions struct {
+type buildCommonOptions struct {
 	HideConsole bool `name:"no-console" help:"Hide console window"`
 }

cmd/syncthing/crash_reporting.go

@@ -10,7 +10,6 @@ import (
 	"bytes"
 	"context"
 	"fmt"
-	"io/ioutil"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -62,7 +61,7 @@ func uploadPanicLogs(ctx context.Context, urlBase, dir string) {
 // the log contents. A HEAD request is made to see if the log has already
 // been reported. If not, a PUT is made with the log contents.
 func uploadPanicLog(ctx context.Context, urlBase, file string) error {
-	data, err := ioutil.ReadFile(file)
+	data, err := os.ReadFile(file)
 	if err != nil {
 		return err
 	}

cmd/syncthing/decrypt/decrypt.go

@@ -12,8 +12,8 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
+	"os"
 	"path/filepath"
 
 	"github.com/syncthing/syncthing/lib/config"
@@ -112,7 +112,7 @@ func (c *CLI) withContinue(err error) error {
 // error.
 func (c *CLI) getFolderID() (string, error) {
 	tokenPath := filepath.Join(c.Path, c.TokenPath)
-	bs, err := ioutil.ReadFile(tokenPath)
+	bs, err := os.ReadFile(tokenPath)
 	if err != nil {
 		return "", fmt.Errorf("reading folder token: %w", err)
 	}

cmd/syncthing/generate/generate.go

@@ -0,0 +1,144 @@
+// Copyright (C) 2021 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+// Package generate implements the `syncthing generate` subcommand.
+package generate
+
+import (
+	"bufio"
+	"context"
+	"crypto/tls"
+	"fmt"
+	"log"
+	"os"
+
+	"github.com/syncthing/syncthing/cmd/syncthing/cmdutil"
+	"github.com/syncthing/syncthing/lib/config"
+	"github.com/syncthing/syncthing/lib/events"
+	"github.com/syncthing/syncthing/lib/fs"
+	"github.com/syncthing/syncthing/lib/locations"
+	"github.com/syncthing/syncthing/lib/osutil"
+	"github.com/syncthing/syncthing/lib/protocol"
+	"github.com/syncthing/syncthing/lib/syncthing"
+)
+
+type CLI struct {
+	cmdutil.CommonOptions
+	GUIUser     string `placeholder:"STRING" help:"Specify new GUI authentication user name"`
+	GUIPassword string `placeholder:"STRING" help:"Specify new GUI authentication password (use - to read from standard input)"`
+}
+
+func (c *CLI) Run() error {
+	log.SetFlags(0)
+
+	if c.HideConsole {
+		osutil.HideConsole()
+	}
+
+	if c.HomeDir != "" {
+		if c.ConfDir != "" {
+			return fmt.Errorf("--home must not be used together with --config")
+		}
+		c.ConfDir = c.HomeDir
+	}
+	if c.ConfDir == "" {
+		c.ConfDir = locations.GetBaseDir(locations.ConfigBaseDir)
+	}
+
+	// Support reading the password from a pipe or similar
+	if c.GUIPassword == "-" {
+		reader := bufio.NewReader(os.Stdin)
+		password, _, err := reader.ReadLine()
+		if err != nil {
+			return fmt.Errorf("Failed reading GUI password: %w", err)
+		}
+		c.GUIPassword = string(password)
+	}
+
+	if err := Generate(c.ConfDir, c.GUIUser, c.GUIPassword, c.NoDefaultFolder); err != nil {
+		return fmt.Errorf("Failed to generate config and keys: %w", err)
+	}
+	return nil
+}
+
+func Generate(confDir, guiUser, guiPassword string, noDefaultFolder bool) error {
+	dir, err := fs.ExpandTilde(confDir)
+	if err != nil {
+		return err
+	}
+
+	if err := syncthing.EnsureDir(dir, 0700); err != nil {
+		return err
+	}
+	locations.SetBaseDir(locations.ConfigBaseDir, dir)
+
+	var myID protocol.DeviceID
+	certFile, keyFile := locations.Get(locations.CertFile), locations.Get(locations.KeyFile)
+	cert, err := tls.LoadX509KeyPair(certFile, keyFile)
+	if err == nil {
+		log.Println("WARNING: Key exists; will not overwrite.")
+	} else {
+		cert, err = syncthing.GenerateCertificate(certFile, keyFile)
+		if err != nil {
+			return fmt.Errorf("create certificate: %w", err)
+		}
+	}
+	myID = protocol.NewDeviceID(cert.Certificate[0])
+	log.Println("Device ID:", myID)
+
+	cfgFile := locations.Get(locations.ConfigFile)
+	var cfg config.Wrapper
+	if _, err := os.Stat(cfgFile); err == nil {
+		if guiUser == "" && guiPassword == "" {
+			log.Println("WARNING: Config exists; will not overwrite.")
+			return nil
+		}
+
+		if cfg, _, err = config.Load(cfgFile, myID, events.NoopLogger); err != nil {
+			return fmt.Errorf("load config: %w", err)
+		}
+	} else {
+		if cfg, err = syncthing.DefaultConfig(cfgFile, myID, events.NoopLogger, noDefaultFolder); err != nil {
+			return fmt.Errorf("create config: %w", err)
+		}
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	go cfg.Serve(ctx)
+	defer cancel()
+
+	var updateErr error
+	waiter, err := cfg.Modify(func(cfg *config.Configuration) {
+		updateErr = updateGUIAuthentication(&cfg.GUI, guiUser, guiPassword)
+	})
+	if err != nil {
+		return fmt.Errorf("modify config: %w", err)
+	}
+
+	waiter.Wait()
+	if updateErr != nil {
+		return updateErr
+	}
+	if err := cfg.Save(); err != nil {
+		return fmt.Errorf("save config: %w", err)
+	}
+	return nil
+}
+
+func updateGUIAuthentication(guiCfg *config.GUIConfiguration, guiUser, guiPassword string) error {
+	if guiUser != "" && guiCfg.User != guiUser {
+		guiCfg.User = guiUser
+		log.Println("Updated GUI authentication user name:", guiUser)
+	}
+
+	if guiPassword != "" && guiCfg.Password != guiPassword {
+		if err := guiCfg.HashAndSetPassword(guiPassword); err != nil {
+			return fmt.Errorf("Failed to set GUI authentication password: %w", err)
+		}
+		log.Println("Updated GUI authentication password.")
+	}
+	return nil
+}

cmd/syncthing/main.go

@@ -12,7 +12,6 @@ import (
 	"crypto/tls"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"net/http"
 	_ "net/http/pprof" // Need to import this to support STPROFILER.
@@ -36,6 +35,7 @@ import (
 	"github.com/syncthing/syncthing/cmd/syncthing/cli"
 	"github.com/syncthing/syncthing/cmd/syncthing/cmdutil"
 	"github.com/syncthing/syncthing/cmd/syncthing/decrypt"
+	"github.com/syncthing/syncthing/cmd/syncthing/generate"
 	"github.com/syncthing/syncthing/lib/build"
 	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/db"
@@ -132,32 +132,30 @@ var (
 // commands and options here are top level commands to syncthing.
 // Cli is just a placeholder for the help text (see main).
 var entrypoint struct {
-	Serve   serveOptions `cmd:"" help:"Run Syncthing"`
-	Decrypt decrypt.CLI  `cmd:"" help:"Decrypt or verify an encrypted folder"`
-	Cli     struct{}     `cmd:"" help:"Command line interface for Syncthing"`
+	Serve    serveOptions `cmd:"" help:"Run Syncthing"`
+	Generate generate.CLI `cmd:"" help:"Generate key and config, then exit"`
+	Decrypt  decrypt.CLI  `cmd:"" help:"Decrypt or verify an encrypted folder"`
+	Cli      struct{}     `cmd:"" help:"Command line interface for Syncthing"`
 }
 
 // serveOptions are the options for the `syncthing serve` command.
 type serveOptions struct {
-	buildServeOptions
+	cmdutil.CommonOptions
 	AllowNewerConfig bool   `help:"Allow loading newer than current config version"`
 	Audit            bool   `help:"Write events to audit file"`
 	AuditFile        string `name:"auditfile" placeholder:"PATH" help:"Specify audit file (use \"-\" for stdout, \"--\" for stderr)"`
 	BrowserOnly      bool   `help:"Open GUI in browser"`
-	ConfDir          string `name:"config" placeholder:"PATH" help:"Set configuration directory (config and keys)"`
 	DataDir          string `name:"data" placeholder:"PATH" help:"Set data directory (database and logs)"`
 	DeviceID         bool   `help:"Show the device ID"`
-	GenerateDir      string `name:"generate" placeholder:"PATH" help:"Generate key and config in specified dir, then exit"`
+	GenerateDir      string `name:"generate" placeholder:"PATH" help:"Generate key and config in specified dir, then exit"` //DEPRECATED: replaced by subcommand!
 	GUIAddress       string `name:"gui-address" placeholder:"URL" help:"Override GUI address (e.g. \"http://192.0.2.42:8443\")"`
 	GUIAPIKey        string `name:"gui-apikey" placeholder:"API-KEY" help:"Override GUI API key"`
-	HomeDir          string `name:"home" placeholder:"PATH" help:"Set configuration and data directory"`
 	LogFile          string `name:"logfile" default:"${logFile}" placeholder:"PATH" help:"Log file name (see below)"`
 	LogFlags         int    `name:"logflags" default:"${logFlags}" placeholder:"BITS" help:"Select information in log line prefix (see below)"`
 	LogMaxFiles      int    `placeholder:"N" default:"${logMaxFiles}" name:"log-max-old-files" help:"Number of old files to keep (zero to keep only current)"`
 	LogMaxSize       int    `placeholder:"BYTES" default:"${logMaxSize}" help:"Maximum size of any file (zero to disable log rotation)"`
 	NoBrowser        bool   `help:"Do not start browser"`
 	NoRestart        bool   `env:"STNORESTART" help:"Do not restart Syncthing when exiting due to API/GUI command, upgrade, or crash"`
-	NoDefaultFolder  bool   `env:"STNODEFAULTFOLDER" help:"Don't create the \"default\" folder on first startup"`
 	NoUpgrade        bool   `env:"STNOUPGRADE" help:"Disable automatic upgrades"`
 	Paths            bool   `help:"Show configuration paths"`
 	Paused           bool   `help:"Start with all devices and folders paused"`
@@ -339,7 +337,7 @@ func (options serveOptions) Run() error {
 	}
 
 	if options.GenerateDir != "" {
-		if err := generate(options.GenerateDir, options.NoDefaultFolder); err != nil {
+		if err := generate.Generate(options.GenerateDir, "", "", options.NoDefaultFolder); err != nil {
 			l.Warnln("Failed to generate config and keys:", err)
 			os.Exit(svcutil.ExitError.AsInt())
 		}
@@ -347,7 +345,7 @@ func (options serveOptions) Run() error {
 	}
 
 	// Ensure that our home directory exists.
-	if err := ensureDir(locations.GetBaseDir(locations.ConfigBaseDir), 0700); err != nil {
+	if err := syncthing.EnsureDir(locations.GetBaseDir(locations.ConfigBaseDir), 0700); err != nil {
 		l.Warnln("Failure on home directory:", err)
 		os.Exit(svcutil.ExitError.AsInt())
 	}
@@ -413,8 +411,8 @@ func openGUI(myID protocol.DeviceID) error {
 	if err != nil {
 		return err
 	}
-	if cfg.GUI().Enabled {
-		if err := openURL(cfg.GUI().URL()); err != nil {
+	if guiCfg := cfg.GUI(); guiCfg.Enabled {
+		if err := openURL(guiCfg.URL()); err != nil {
 			return err
 		}
 	} else {
@@ -423,46 +421,6 @@ func openGUI(myID protocol.DeviceID) error {
 	return nil
 }
 
-func generate(generateDir string, noDefaultFolder bool) error {
-	dir, err := fs.ExpandTilde(generateDir)
-	if err != nil {
-		return err
-	}
-
-	if err := ensureDir(dir, 0700); err != nil {
-		return err
-	}
-
-	var myID protocol.DeviceID
-	certFile, keyFile := filepath.Join(dir, "cert.pem"), filepath.Join(dir, "key.pem")
-	cert, err := tls.LoadX509KeyPair(certFile, keyFile)
-	if err == nil {
-		l.Warnln("Key exists; will not overwrite.")
-	} else {
-		cert, err = syncthing.GenerateCertificate(certFile, keyFile)
-		if err != nil {
-			return errors.Wrap(err, "create certificate")
-		}
-	}
-	myID = protocol.NewDeviceID(cert.Certificate[0])
-	l.Infoln("Device ID:", myID)
-
-	cfgFile := filepath.Join(dir, "config.xml")
-	if _, err := os.Stat(cfgFile); err == nil {
-		l.Warnln("Config exists; will not overwrite.")
-		return nil
-	}
-	cfg, err := syncthing.DefaultConfig(cfgFile, myID, events.NoopLogger, noDefaultFolder)
-	if err != nil {
-		return err
-	}
-	err = cfg.Save()
-	if err != nil {
-		return errors.Wrap(err, "save config")
-	}
-	return nil
-}
-
 func debugFacilities() string {
 	facilities := l.Facilities()
 
@@ -541,7 +499,7 @@ func upgradeViaRest() error {
 		return err
 	}
 	if resp.StatusCode != 200 {
-		bs, err := ioutil.ReadAll(resp.Body)
+		bs, err := io.ReadAll(resp.Body)
 		defer resp.Body.Close()
 		if err != nil {
 			return err
@@ -800,29 +758,6 @@ func resetDB() error {
 	return os.RemoveAll(locations.Get(locations.Database))
 }
 
-func ensureDir(dir string, mode fs.FileMode) error {
-	fs := fs.NewFilesystem(fs.FilesystemTypeBasic, dir)
-	err := fs.MkdirAll(".", mode)
-	if err != nil {
-		return err
-	}
-
-	if fi, err := fs.Stat("."); err == nil {
-		// Apprently the stat may fail even though the mkdirall passed. If it
-		// does, we'll just assume things are in order and let other things
-		// fail (like loading or creating the config...).
-		currentMode := fi.Mode() & 0777
-		if currentMode != mode {
-			err := fs.Chmod(".", mode)
-			// This can fail on crappy filesystems, nothing we can do about it.
-			if err != nil {
-				l.Warnln(err)
-			}
-		}
-	}
-	return nil
-}
-
 func standbyMonitor(app *syncthing.App, cfg config.Wrapper) {
 	restartDelay := 60 * time.Second
 	now := time.Now()

cmd/syncthing/monitor_test.go

@@ -8,7 +8,6 @@ package main
 
 import (
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -18,7 +17,7 @@ import (
 func TestRotatedFile(t *testing.T) {
 	// Verify that log rotation happens.
 
-	dir, err := ioutil.TempDir("", "syncthing")
+	dir, err := os.MkdirTemp("", "syncthing")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -179,7 +178,7 @@ func TestAutoClosedFile(t *testing.T) {
 	}
 
 	// The file should have both writes in it.
-	bs, err := ioutil.ReadFile(file)
+	bs, err := os.ReadFile(file)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -199,7 +198,7 @@ func TestAutoClosedFile(t *testing.T) {
 	}
 
 	// It should now contain three writes, as the file is always opened for appending
-	bs, err = ioutil.ReadFile(file)
+	bs, err = os.ReadFile(file)
 	if err != nil {
 		t.Fatal(err)
 	}

cmd/ursrv/main.go

@@ -13,7 +13,6 @@ import (
 	"encoding/json"
 	"html/template"
 	"io"
-	"io/ioutil"
 	"log"
 	"net"
 	"net/http"
@@ -162,7 +161,7 @@ func main() {
 	if err != nil {
 		log.Fatalln("template:", err)
 	}
-	bs, err := ioutil.ReadAll(fd)
+	bs, err := io.ReadAll(fd)
 	if err != nil {
 		log.Fatalln("template:", err)
 	}
@@ -324,7 +323,7 @@ func newDataHandler(db *sql.DB, w http.ResponseWriter, r *http.Request) {
 	rep.Address = addr
 
 	lr := &io.LimitedReader{R: r.Body, N: 40 * 1024}
-	bs, _ := ioutil.ReadAll(lr)
+	bs, _ := io.ReadAll(lr)
 	if err := json.Unmarshal(bs, &rep); err != nil {
 		log.Println("decode:", err)
 		if debug {

go.mod

@@ -30,7 +30,7 @@ require (
 	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51
 	github.com/klauspost/cpuid/v2 v2.0.9 // indirect
 	github.com/lib/pq v1.10.3
-	github.com/lucas-clemente/quic-go v0.23.0
+	github.com/lucas-clemente/quic-go v0.24.0
 	github.com/maruel/panicparse v1.6.1
 	github.com/maxbrunsfeld/counterfeiter/v6 v6.3.0
 	github.com/minio/sha256-simd v1.0.0

go.sum

@@ -242,8 +242,8 @@ github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/lib/pq v1.10.3 h1:v9QZf2Sn6AmjXtQeFpdoq/eaNtYP6IN+7lcrygsIAtg=
 github.com/lib/pq v1.10.3/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
 github.com/lucas-clemente/quic-go v0.22.0/go.mod h1:vF5M1XqhBAHgbjKcJOXY3JZz3GP0T3FQhz/uyOUS38Q=
-github.com/lucas-clemente/quic-go v0.23.0 h1:5vFnKtZ6nHDFsc/F3uuiF4T3y/AXaQdxjUqiVw26GZE=
-github.com/lucas-clemente/quic-go v0.23.0/go.mod h1:paZuzjXCE5mj6sikVLMvqXk8lJV2AsqtJ6bDhjEfxx0=
+github.com/lucas-clemente/quic-go v0.24.0 h1:ToR7SIIEdrgOhgVTHvPgdVRJfgVy+N0wQAagH7L4d5g=
+github.com/lucas-clemente/quic-go v0.24.0/go.mod h1:paZuzjXCE5mj6sikVLMvqXk8lJV2AsqtJ6bDhjEfxx0=
 github.com/lunixbochs/vtclean v1.0.0/go.mod h1:pHhQNgMf3btfWnGBVipUOjRYhoOsdGqdm/+2c2E2WMI=
 github.com/mailru/easyjson v0.0.0-20190312143242-1de009706dbe/go.mod h1:C1wdFJiN94OJF2b5HbByQZoLdCWB1Yqtg26g4irojpc=
 github.com/marten-seemann/qpack v0.2.1/go.mod h1:F7Gl5L1jIgN1D11ucXefiuJS9UMVP2opoCp2jDKb7wc=

gui/default/index.html

@@ -428,6 +428,13 @@
                           <div ng-if="model[folder.id].ignorePatterns">
                             <a href="" ng-click="editFolderExisting(folder, '#folder-ignores')"><i class="small" translate>Reduced by ignore patterns</i></a>
                           </div>
+                          <div ng-if="folder.ignoreDelete">
+                            <i class="small">
+                              <span translate style="white-space: normal;">Altered by ignoring deletes.</span>
+                              <br>
+                              <a href="https://docs.syncthing.net/advanced/folder-ignoredelete" target="_blank"><span class="fas fa-question-circle"></span>&nbsp;<span translate>Help</span></a>
+                            </i>
+                          </div>
                         </td>
                       </tr>
                       <tr ng-if="model[folder.id].needTotalItems > 0">

gui/default/syncthing/device/removeDeviceDialogView.html

@@ -1,9 +1,11 @@
 <modal id="remove-device-confirmation" status="warning" icon="fas fa-question-circle" heading="{{'Remove Device' | translate}}" large="no" closeable="yes">
   <div class="modal-body">
-    <p ng-model="currentDevice.name" style="overflow: hidden; text-overflow: ellipsis; white-space: nowrap;">
-      <span translate translate-value-name="{{currentDevice.name}}">Are you sure you want to remove device {%name%}?</span>
+    <p ng-model="currentDevice.name" translate translate-value-name="{{currentDevice.name}}">
+      Are you sure you want to remove device {%name%}?
+    </p>
+    <p ng-if="willBeReintroducedBy" translate translate-value-reintroducer="{{willBeReintroducedBy}}">
+      {%reintroducer%} might reintroduce this device.
     </p>
-    <p ng-if="willBeReintroducedBy" translate translate-value-reintroducer="{{willBeReintroducedBy}}">{%reintroducer%} might reintroduce this device.</p>
   </div>
   <div class="modal-footer">
     <button type="button" class="btn btn-warning pull-left btn-sm" data-dismiss="modal" ng-click="deleteDevice()">

gui/default/syncthing/folder/removeFolderDialogView.html

@@ -1,7 +1,7 @@
 <modal id="remove-folder-confirmation" status="warning" icon="fas fa-question-circle" heading="{{'Remove Folder' | translate}}" large="no" closeable="yes">
   <div class="modal-body">
-    <p style="overflow: hidden; text-overflow: ellipsis; white-space: nowrap;">
-      <span translate translate-value-label="{{currentFolder.label}}">Are you sure you want to remove folder {%label%}?</span>
+    <p translate translate-value-label="{{currentFolder.label}}">
+      Are you sure you want to remove folder {%label%}?
     </p>
     <p translate>
       No files will be deleted as a result of this operation.

lib/api/api.go

@@ -15,7 +15,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"net"
 	"net/http"
@@ -94,6 +93,8 @@ type service struct {
 	systemLog logger.Recorder
 }
 
+var _ config.Verifier = &service{}
+
 type Service interface {
 	suture.Service
 	config.Committer
@@ -380,7 +381,7 @@ func (s *service) Serve(ctx context.Context) error {
 		ReadTimeout: 15 * time.Second,
 		// Prevent the HTTP server from logging stuff on its own. The things we
 		// care about we log ourselves from the handlers.
-		ErrorLog: log.New(ioutil.Discard, "", 0),
+		ErrorLog: log.New(io.Discard, "", 0),
 	}
 
 	l.Infoln("GUI and API listening on", listener.Addr())
@@ -1096,7 +1097,7 @@ func (s *service) getSystemError(w http.ResponseWriter, r *http.Request) {
 }
 
 func (s *service) postSystemError(w http.ResponseWriter, r *http.Request) {
-	bs, _ := ioutil.ReadAll(r.Body)
+	bs, _ := io.ReadAll(r.Body)
 	r.Body.Close()
 	l.Warnln(string(bs))
 }
@@ -1163,7 +1164,7 @@ func (s *service) getSupportBundle(w http.ResponseWriter, r *http.Request) {
 	// Panic files
 	if panicFiles, err := filepath.Glob(filepath.Join(locations.GetBaseDir(locations.ConfigBaseDir), "panic*")); err == nil {
 		for _, f := range panicFiles {
-			if panicFile, err := ioutil.ReadFile(f); err != nil {
+			if panicFile, err := os.ReadFile(f); err != nil {
 				l.Warnf("Support bundle: failed to load %s: %s", filepath.Base(f), err)
 			} else {
 				files = append(files, fileEntry{name: filepath.Base(f), data: panicFile})
@@ -1172,7 +1173,7 @@ func (s *service) getSupportBundle(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Archived log (default on Windows)
-	if logFile, err := ioutil.ReadFile(locations.Get(locations.LogFile)); err == nil {
+	if logFile, err := os.ReadFile(locations.Get(locations.LogFile)); err == nil {
 		files = append(files, fileEntry{name: "log-ondisk.txt", data: logFile})
 	}
 
@@ -1231,7 +1232,7 @@ func (s *service) getSupportBundle(w http.ResponseWriter, r *http.Request) {
 	zipFilePath := filepath.Join(locations.GetBaseDir(locations.ConfigBaseDir), zipFileName)
 
 	// Write buffer zip to local zip file (back up)
-	if err := ioutil.WriteFile(zipFilePath, zipFilesBuffer.Bytes(), 0600); err != nil {
+	if err := os.WriteFile(zipFilePath, zipFilesBuffer.Bytes(), 0600); err != nil {
 		l.Warnln("Support bundle: support bundle zip could not be created:", err)
 	}
 
@@ -1321,7 +1322,7 @@ func (s *service) getDBIgnores(w http.ResponseWriter, r *http.Request) {
 func (s *service) postDBIgnores(w http.ResponseWriter, r *http.Request) {
 	qs := r.URL.Query()
 
-	bs, err := ioutil.ReadAll(r.Body)
+	bs, err := io.ReadAll(r.Body)
 	r.Body.Close()
 	if err != nil {
 		http.Error(w, err.Error(), 500)
@@ -1612,7 +1613,7 @@ func (s *service) getFolderVersions(w http.ResponseWriter, r *http.Request) {
 func (s *service) postFolderVersionsRestore(w http.ResponseWriter, r *http.Request) {
 	qs := r.URL.Query()
 
-	bs, err := ioutil.ReadAll(r.Body)
+	bs, err := io.ReadAll(r.Body)
 	r.Body.Close()
 	if err != nil {
 		http.Error(w, err.Error(), 500)

lib/api/api_test.go

@@ -13,7 +13,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net"
 	"net/http"
 	"net/http/httptest"
@@ -223,7 +222,7 @@ func expectURLToContain(t *testing.T, url, exp string) {
 		return
 	}
 
-	data, err := ioutil.ReadAll(res.Body)
+	data, err := io.ReadAll(res.Body)
 	res.Body.Close()
 	if err != nil {
 		t.Error(err)
@@ -508,7 +507,7 @@ func testHTTPRequest(t *testing.T, baseURL string, tc httpTestCase, apikey strin
 		return
 	}
 
-	data, err := ioutil.ReadAll(resp.Body)
+	data, err := io.ReadAll(resp.Body)
 	if err != nil {
 		t.Errorf("Unexpected error reading %s: %v", tc.URL, err)
 		return
@@ -1137,7 +1136,7 @@ func TestBrowse(t *testing.T) {
 
 	pathSep := string(os.PathSeparator)
 
-	tmpDir, err := ioutil.TempDir("", "syncthing")
+	tmpDir, err := os.MkdirTemp("", "syncthing")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1146,7 +1145,7 @@ func TestBrowse(t *testing.T) {
 	if err := os.Mkdir(filepath.Join(tmpDir, "dir"), 0755); err != nil {
 		t.Fatal(err)
 	}
-	if err := ioutil.WriteFile(filepath.Join(tmpDir, "file"), []byte("hello"), 0644); err != nil {
+	if err := os.WriteFile(filepath.Join(tmpDir, "file"), []byte("hello"), 0644); err != nil {
 		t.Fatal(err)
 	}
 	if err := os.Mkdir(filepath.Join(tmpDir, "MiXEDCase"), 0755); err != nil {
@@ -1251,7 +1250,7 @@ func TestConfigChanges(t *testing.T) {
 			APIKey:     testAPIKey,
 		},
 	}
-	tmpFile, err := ioutil.TempFile("", "syncthing-testConfig-")
+	tmpFile, err := os.CreateTemp("", "syncthing-testConfig-")
 	if err != nil {
 		panic(err)
 	}
@@ -1393,7 +1392,7 @@ func runningInContainer() bool {
 		return false
 	}
 
-	bs, err := ioutil.ReadFile("/proc/1/cgroup")
+	bs, err := os.ReadFile("/proc/1/cgroup")
 	if err != nil {
 		return false
 	}

lib/api/auto/auto_test.go

@@ -9,7 +9,7 @@ package auto_test
 import (
 	"bytes"
 	"compress/gzip"
-	"io/ioutil"
+	"io"
 	"strings"
 	"testing"
 
@@ -28,7 +28,7 @@ func TestAssets(t *testing.T) {
 
 	var gr *gzip.Reader
 	gr, _ = gzip.NewReader(strings.NewReader(idx.Content))
-	html, _ := ioutil.ReadAll(gr)
+	html, _ := io.ReadAll(gr)
 
 	if !bytes.Contains(html, []byte("<html")) {
 		t.Fatal("No html in index.html")

lib/api/confighandler.go

@@ -9,7 +9,6 @@ package api
 import (
 	"encoding/json"
 	"io"
-	"io/ioutil"
 	"net/http"
 
 	"github.com/julienschmidt/httprouter"
@@ -407,7 +406,7 @@ func (c *configMuxBuilder) adjustLDAP(w http.ResponseWriter, r *http.Request, ld
 
 // Unmarshals the content of the given body and stores it in to (i.e. to must be a pointer).
 func unmarshalTo(body io.ReadCloser, to interface{}) error {
-	bs, err := ioutil.ReadAll(body)
+	bs, err := io.ReadAll(body)
 	body.Close()
 	if err != nil {
 		return err

lib/assets/assets_test.go

@@ -10,7 +10,6 @@ import (
 	"bytes"
 	"compress/gzip"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
 	"strconv"
@@ -31,7 +30,7 @@ func compress(s string) string {
 func decompress(p []byte) (out []byte) {
 	r, err := gzip.NewReader(bytes.NewBuffer(p))
 	if err == nil {
-		out, err = ioutil.ReadAll(r)
+		out, err = io.ReadAll(r)
 	}
 	if err != nil {
 		panic(err)
@@ -81,7 +80,7 @@ func testServe(t *testing.T, gzip bool) {
 			t.Errorf("unexpected ETag %q", etag)
 		}
 
-		body, _ := ioutil.ReadAll(res.Body)
+		body, _ := io.ReadAll(res.Body)
 
 		// Content-Length is the number of bytes in the encoded (compressed) body
 		// (https://stackoverflow.com/a/3819303).

lib/config/config.go

@@ -12,7 +12,6 @@ import (
 	"encoding/xml"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net"
 	"net/url"
 	"os"
@@ -163,7 +162,7 @@ func ReadXML(r io.Reader, myID protocol.DeviceID) (Configuration, int, error) {
 }
 
 func ReadJSON(r io.Reader, myID protocol.DeviceID) (Configuration, error) {
-	bs, err := ioutil.ReadAll(r)
+	bs, err := io.ReadAll(r)
 	if err != nil {
 		return Configuration{}, err
 	}

lib/config/config_test.go

@@ -13,7 +13,6 @@ import (
 	"encoding/xml"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -502,7 +501,7 @@ func TestFolderPath(t *testing.T) {
 }
 
 func TestFolderCheckPath(t *testing.T) {
-	n, err := ioutil.TempDir("", "")
+	n, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -595,6 +594,41 @@ func TestNewSaveLoad(t *testing.T) {
 	}
 }
 
+func TestWindowsLineEndings(t *testing.T) {
+	if runtime.GOOS != "windows" {
+		t.Skip("Windows specific")
+	}
+
+	dir, err := os.MkdirTemp("", "syncthing-test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+
+	path := filepath.Join(dir, "config.xml")
+	os.Remove(path)
+	defer os.Remove(path)
+
+	intCfg := New(device1)
+	cfg := wrap(path, intCfg, device1)
+	defer cfg.stop()
+
+	if err := cfg.Save(); err != nil {
+		t.Error(err)
+	}
+
+	bs, err := os.ReadFile(path)
+	if err != nil {
+		t.Error(err)
+	}
+
+	unixLineEndings := bytes.Count(bs, []byte("\n"))
+	windowsLineEndings := bytes.Count(bs, []byte("\r\n"))
+	if unixLineEndings == 0 || windowsLineEndings != unixLineEndings {
+		t.Error("expected there to be a non-zero number of Windows line endings")
+	}
+}
+
 func TestPrepare(t *testing.T) {
 	var cfg Configuration
 
@@ -643,8 +677,8 @@ func TestCopy(t *testing.T) {
 		t.Error("Config should have changed")
 	}
 	if !bytes.Equal(bsOrig, bsCopy) {
-		// ioutil.WriteFile("a", bsOrig, 0644)
-		// ioutil.WriteFile("b", bsCopy, 0644)
+		// os.WriteFile("a", bsOrig, 0644)
+		// os.WriteFile("b", bsCopy, 0644)
 		t.Error("Copy should be unchanged")
 	}
 }
@@ -1266,7 +1300,7 @@ func copyToTmp(path string) (string, error) {
 		return "", err
 	}
 	defer orig.Close()
-	temp, err := ioutil.TempFile("", "syncthing-configTest-")
+	temp, err := os.CreateTemp("", "syncthing-configTest-")
 	if err != nil {
 		return "", err
 	}

lib/config/wrapper.go

@@ -31,14 +31,14 @@ const (
 
 var errTooManyModifications = errors.New("too many concurrent config modifications")
 
-// The Committer interface is implemented by objects that need to know about
-// or have a say in configuration changes.
+// The Committer and Verifier interfaces are implemented by objects
+// that need to know about or have a say in configuration changes.
 //
 // When the configuration is about to be changed, VerifyConfiguration() is
-// called for each subscribing object, with the old and new configuration. A
-// nil error is returned if the new configuration is acceptable (i.e. does not
-// contain any errors that would prevent it from being a valid config).
-// Otherwise an error describing the problem is returned.
+// called for each subscribing object that implements it, with copies of the
+// old and new configuration. A nil error is returned if the new configuration
+// is acceptable (i.e., does not contain any errors that would prevent it from
+// being a valid config). Otherwise an error describing the problem is returned.
 //
 // If any subscriber returns an error from VerifyConfiguration(), the
 // configuration change is not committed and an error is returned to whoever
@@ -55,11 +55,16 @@ var errTooManyModifications = errors.New("too many concurrent config modificatio
 // configuration (e.g. calling Wrapper.SetFolder), that are also acquired in any
 // methods of the Committer interface.
 type Committer interface {
-	VerifyConfiguration(from, to Configuration) error
 	CommitConfiguration(from, to Configuration) (handled bool)
 	String() string
 }
 
+// A Verifier can determine if a new configuration is acceptable.
+// See the description for Committer, above.
+type Verifier interface {
+	VerifyConfiguration(from, to Configuration) error
+}
+
 // Waiter allows to wait for the given config operation to complete.
 type Waiter interface {
 	Wait()
@@ -300,6 +305,10 @@ func (w *wrapper) replaceLocked(to Configuration) (Waiter, error) {
 	}
 
 	for _, sub := range w.subs {
+		sub, ok := sub.(Verifier)
+		if !ok {
+			continue
+		}
 		l.Debugln(sub, "verifying configuration")
 		if err := sub.VerifyConfiguration(from.Copy(), to.Copy()); err != nil {
 			l.Debugln(sub, "rejected config:", err)
@@ -493,7 +502,7 @@ func (w *wrapper) Save() error {
 		return err
 	}
 
-	if err := w.cfg.WriteXML(fd); err != nil {
+	if err := w.cfg.WriteXML(osutil.LineEndingsWriter(fd)); err != nil {
 		l.Debugln("WriteXML:", err)
 		fd.Close()
 		return err

lib/connections/limiter.go

@@ -122,10 +122,6 @@ func (lim *limiter) processDevicesConfigurationLocked(from, to config.Configurat
 	}
 }
 
-func (lim *limiter) VerifyConfiguration(from, to config.Configuration) error {
-	return nil
-}
-
 func (lim *limiter) CommitConfiguration(from, to config.Configuration) bool {
 	// to ensure atomic update of configuration
 	lim.mu.Lock()

lib/connections/service.go

@@ -706,10 +706,6 @@ func (s *service) logListenAddressesChangedEvent(l ListenerAddresses) {
 	})
 }
 
-func (s *service) VerifyConfiguration(from, to config.Configuration) error {
-	return nil
-}
-
 func (s *service) CommitConfiguration(from, to config.Configuration) bool {
 	newDevices := make(map[protocol.DeviceID]bool, len(to.Devices))
 	for _, dev := range to.Devices {

lib/connections/tcp_listen.go

@@ -76,7 +76,7 @@ func (t *tcpListener) serve(ctx context.Context) error {
 	defer l.Infof("TCP listener (%v) shutting down", tcaddr)
 
 	mapping := t.natService.NewMapping(nat.TCP, tcaddr.IP, tcaddr.Port)
-	mapping.OnChanged(func(_ *nat.Mapping, _, _ []nat.Address) {
+	mapping.OnChanged(func() {
 		t.notifyAddressesChanged(t)
 	})
 	// Should be called after t.mapping is nil'ed out.

lib/discover/global.go

@@ -14,7 +14,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"net/url"
 	"strconv"
@@ -173,7 +172,7 @@ func (c *globalClient) Lookup(ctx context.Context, device protocol.DeviceID) (ad
 		return nil, err
 	}
 
-	bs, err := ioutil.ReadAll(resp.Body)
+	bs, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return nil, err
 	}

lib/discover/global_test.go

@@ -9,7 +9,7 @@ package discover
 import (
 	"context"
 	"crypto/tls"
-	"io/ioutil"
+	"io"
 	"net"
 	"net/http"
 	"strings"
@@ -232,7 +232,7 @@ func (s *fakeDiscoveryServer) handler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if r.Method == "POST" {
-		s.announce, _ = ioutil.ReadAll(r.Body)
+		s.announce, _ = io.ReadAll(r.Body)
 		w.WriteHeader(204)
 	} else {
 		w.Header().Set("Content-Type", "application/json")

lib/discover/manager.go

@@ -227,10 +227,6 @@ func (m *manager) Cache() map[protocol.DeviceID]CacheEntry {
 	return res
 }
 
-func (m *manager) VerifyConfiguration(_, _ config.Configuration) error {
-	return nil
-}
-
 func (m *manager) CommitConfiguration(_, to config.Configuration) (handled bool) {
 	m.mut.Lock()
 	defer m.mut.Unlock()

lib/fs/basicfs_test.go

@@ -7,7 +7,6 @@
 package fs
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -21,7 +20,7 @@ import (
 
 func setup(t *testing.T) (*BasicFilesystem, string) {
 	t.Helper()
-	dir, err := ioutil.TempDir("", "")
+	dir, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatal(err)
 	}

lib/fs/basicfs_watch_test.go

@@ -13,7 +13,6 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -530,7 +529,7 @@ func renameTestFile(name string, old string, new string) {
 func modifyTestFile(name string, file string, content string) {
 	joined := filepath.Join(testDirAbs, name, file)
 
-	err := ioutil.WriteFile(joined, []byte(content), 0755)
+	err := os.WriteFile(joined, []byte(content), 0755)
 	if err != nil {
 		panic(fmt.Sprintf("Failed to modify test file %s: %s", joined, err))
 	}

lib/fs/fakefs.go

@@ -12,7 +12,6 @@ import (
 	"fmt"
 	"hash/fnv"
 	"io"
-	"io/ioutil"
 	"math/rand"
 	"net/url"
 	"os"
@@ -89,11 +88,9 @@ func newFakeFilesystem(rootURI string, _ ...Option) *fakeFS {
 	fakeFSMut.Lock()
 	defer fakeFSMut.Unlock()
 
-	root := rootURI
 	var params url.Values
 	uri, err := url.Parse(rootURI)
 	if err == nil {
-		root = uri.Path
 		params = uri.Query()
 	}
 
@@ -157,7 +154,7 @@ func newFakeFilesystem(rootURI string, _ ...Option) *fakeFS {
 	// the filesystem initially.
 	fs.latency, _ = time.ParseDuration(params.Get("latency"))
 
-	fakeFSCache[root] = fs
+	fakeFSCache[rootURI] = fs
 	return fs
 }
 
@@ -789,7 +786,7 @@ func (f *fakeFile) readShortAt(p []byte, offs int64) (int, error) {
 		diff := offs - minOffs
 		if diff > 0 {
 			lr := io.LimitReader(f.rng, diff)
-			io.Copy(ioutil.Discard, lr)
+			io.Copy(io.Discard, lr)
 		}
 
 		f.offset = offs

lib/fs/fakefs_test.go

@@ -10,7 +10,6 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"path"
 	"path/filepath"
@@ -88,7 +87,7 @@ func TestFakeFS(t *testing.T) {
 	}
 
 	// Read
-	bs0, err := ioutil.ReadAll(fd)
+	bs0, err := io.ReadAll(fd)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -101,7 +100,7 @@ func TestFakeFS(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	bs1, err := ioutil.ReadAll(fd)
+	bs1, err := io.ReadAll(fd)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -139,7 +138,7 @@ func testFakeFSRead(t *testing.T, fs Filesystem) {
 
 	// Read
 	fd.Seek(0, io.SeekStart)
-	bs0, err := ioutil.ReadAll(fd)
+	bs0, err := io.ReadAll(fd)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -154,7 +153,7 @@ func testFakeFSRead(t *testing.T, fs Filesystem) {
 	if n != len(buf0) {
 		t.Fatal("short read")
 	}
-	buf1, err := ioutil.ReadAll(fd)
+	buf1, err := io.ReadAll(fd)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -252,7 +251,7 @@ func TestFakeFSCaseInsensitive(t *testing.T) {
 func createTestDir(t *testing.T) (string, bool) {
 	t.Helper()
 
-	testDir, err := ioutil.TempDir("", "")
+	testDir, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatalf("could not create temporary dir for testing: %s", err)
 	}
@@ -328,7 +327,7 @@ func testFakeFSCaseInsensitive(t *testing.T, fs Filesystem) {
 		t.Fatal(err)
 	}
 
-	bs2, err := ioutil.ReadAll(fd2)
+	bs2, err := io.ReadAll(fd2)
 	if err != nil {
 		t.Fatal(err)
 	}

lib/fs/filesystem.go

@@ -253,7 +253,7 @@ func IsInternal(file string) bool {
 // - /foo/bar -> foo/bar
 // - / -> "."
 func Canonicalize(file string) (string, error) {
-	pathSep := string(PathSeparator)
+	const pathSep = string(PathSeparator)
 
 	if strings.HasPrefix(file, pathSep+pathSep) {
 		// The relative path may pretend to be an absolute path within

lib/fs/filesystem_copy_range_test.go

@@ -9,7 +9,6 @@ package fs
 import (
 	"bytes"
 	"io"
-	"io/ioutil"
 	"math/rand"
 	"os"
 	"path/filepath"
@@ -257,7 +256,7 @@ func TestCopyRange(tttt *testing.T) {
 		paths = []string{""}
 	}
 	for _, path := range paths {
-		testPath, err := ioutil.TempDir(path, "")
+		testPath, err := os.MkdirTemp(path, "")
 		if err != nil {
 			tttt.Fatal(err)
 		}
@@ -273,7 +272,7 @@ func TestCopyRange(tttt *testing.T) {
 						tt.Run(testCase.name, func(t *testing.T) {
 							srcBuf := make([]byte, testCase.srcSize)
 							dstBuf := make([]byte, testCase.dstSize)
-							td, err := ioutil.TempDir(testPath, "")
+							td, err := os.MkdirTemp(testPath, "")
 							if err != nil {
 								t.Fatal(err)
 							}

lib/fs/mtimefs_test.go

@@ -8,7 +8,6 @@ package fs
 
 import (
 	"errors"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -20,9 +19,9 @@ func TestMtimeFS(t *testing.T) {
 	os.RemoveAll("testdata")
 	defer os.RemoveAll("testdata")
 	os.Mkdir("testdata", 0755)
-	ioutil.WriteFile("testdata/exists0", []byte("hello"), 0644)
-	ioutil.WriteFile("testdata/exists1", []byte("hello"), 0644)
-	ioutil.WriteFile("testdata/exists2", []byte("hello"), 0644)
+	os.WriteFile("testdata/exists0", []byte("hello"), 0644)
+	os.WriteFile("testdata/exists1", []byte("hello"), 0644)
+	os.WriteFile("testdata/exists2", []byte("hello"), 0644)
 
 	// a random time with nanosecond precision
 	testTime := time.Unix(1234567890, 123456789)
@@ -83,7 +82,7 @@ func TestMtimeFS(t *testing.T) {
 }
 
 func TestMtimeFSWalk(t *testing.T) {
-	dir, err := ioutil.TempDir("", "")
+	dir, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -93,7 +92,7 @@ func TestMtimeFSWalk(t *testing.T) {
 	mtimefs := newMtimeFS(underlying, make(mapStore))
 	mtimefs.chtimes = failChtimes
 
-	if err := ioutil.WriteFile(filepath.Join(dir, "file"), []byte("hello"), 0644); err != nil {
+	if err := os.WriteFile(filepath.Join(dir, "file"), []byte("hello"), 0644); err != nil {
 		t.Fatal(err)
 	}
 
@@ -137,7 +136,7 @@ func TestMtimeFSWalk(t *testing.T) {
 }
 
 func TestMtimeFSOpen(t *testing.T) {
-	dir, err := ioutil.TempDir("", "")
+	dir, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -147,7 +146,7 @@ func TestMtimeFSOpen(t *testing.T) {
 	mtimefs := newMtimeFS(underlying, make(mapStore))
 	mtimefs.chtimes = failChtimes
 
-	if err := ioutil.WriteFile(filepath.Join(dir, "file"), []byte("hello"), 0644); err != nil {
+	if err := os.WriteFile(filepath.Join(dir, "file"), []byte("hello"), 0644); err != nil {
 		t.Fatal(err)
 	}
 
@@ -200,7 +199,7 @@ func TestMtimeFSInsensitive(t *testing.T) {
 		os.RemoveAll("testdata")
 		defer os.RemoveAll("testdata")
 		os.Mkdir("testdata", 0755)
-		ioutil.WriteFile("testdata/FiLe", []byte("hello"), 0644)
+		os.WriteFile("testdata/FiLe", []byte("hello"), 0644)
 
 		// a random time with nanosecond precision
 		testTime := time.Unix(1234567890, 123456789)

lib/fs/util.go

@@ -47,25 +47,13 @@ func getHomeDir() (string, error) {
 	return os.UserHomeDir()
 }
 
-var (
-	windowsDisallowedCharacters = string([]rune{
-		'<', '>', ':', '"', '|', '?', '*',
-		0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
-		11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
-		21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
-		31,
-	})
-	windowsDisallowedNames = []string{"CON", "PRN", "AUX", "NUL",
-		"COM0", "COM1", "COM2", "COM3", "COM4", "COM5", "COM6", "COM7", "COM8", "COM9",
-		"LPT0", "LPT1", "LPT2", "LPT3", "LPT4", "LPT5", "LPT6", "LPT7", "LPT8", "LPT9",
-	}
-)
+const windowsDisallowedCharacters = (`<>:"|?*` +
+	"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f" +
+	"\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f")
 
 func WindowsInvalidFilename(name string) error {
 	// None of the path components should end in space or period, or be a
-	// reserved name. COM0 and LPT0 are missing from the Microsoft docs,
-	// but Windows Explorer treats them as invalid too.
-	// (https://docs.microsoft.com/windows/win32/fileio/naming-a-file)
+	// reserved name.
 	for _, part := range strings.Split(name, `\`) {
 		if len(part) == 0 {
 			continue
@@ -110,7 +98,7 @@ func WindowsInvalidFilename(name string) error {
 func SanitizePath(path string) string {
 	var b strings.Builder
 
-	disallowed := `<>:"'/\|?*[]{};:!@$%&^#` + windowsDisallowedCharacters
+	const disallowed = `'/\[]{};:!@$%&^#` + windowsDisallowedCharacters
 	prev := ' '
 	for _, c := range path {
 		if !unicode.IsPrint(c) || c == unicode.ReplacementChar ||
@@ -132,15 +120,27 @@ func SanitizePath(path string) string {
 }
 
 func windowsIsReserved(part string) bool {
-	upperCased := strings.ToUpper(part)
-	for _, disallowed := range windowsDisallowedNames {
-		if upperCased == disallowed {
-			return true
-		}
-		if strings.HasPrefix(upperCased, disallowed+".") {
-			// nul.txt.jpg is also disallowed
-			return true
-		}
+	// nul.txt.jpg is also disallowed.
+	dot := strings.IndexByte(part, '.')
+	if dot != -1 {
+		part = part[:dot]
+	}
+
+	// Check length to skip allocating ToUpper.
+	if len(part) != 3 && len(part) != 4 {
+		return false
+	}
+
+	// COM0 and LPT0 are missing from the Microsoft docs,
+	// but Windows Explorer treats them as invalid too.
+	// (https://docs.microsoft.com/windows/win32/fileio/naming-a-file)
+	switch strings.ToUpper(part) {
+	case "CON", "PRN", "AUX", "NUL",
+		"COM0", "COM1", "COM2", "COM3", "COM4",
+		"COM5", "COM6", "COM7", "COM8", "COM9",
+		"LPT0", "LPT1", "LPT2", "LPT3", "LPT4",
+		"LPT5", "LPT6", "LPT7", "LPT8", "LPT9":
+		return true
 	}
 	return false
 }

lib/fs/util_test.go

@@ -117,3 +117,15 @@ func TestSanitizePathFuzz(t *testing.T) {
 		}
 	}
 }
+
+func benchmarkWindowsInvalidFilename(b *testing.B, name string) {
+	for i := 0; i < b.N; i++ {
+		WindowsInvalidFilename(name)
+	}
+}
+func BenchmarkWindowsInvalidFilenameValid(b *testing.B) {
+	benchmarkWindowsInvalidFilename(b, "License.txt.gz")
+}
+func BenchmarkWindowsInvalidFilenameNUL(b *testing.B) {
+	benchmarkWindowsInvalidFilename(b, "nul.txt.gz")
+}

lib/ignore/ignore.go

@@ -595,8 +595,9 @@ func WriteIgnores(filesystem fs.Filesystem, path string, content []string) error
 		return err
 	}
 
+	wr := osutil.LineEndingsWriter(fd)
 	for _, line := range content {
-		fmt.Fprintln(fd, line)
+		fmt.Fprintln(wr, line)
 	}
 
 	if err := fd.Close(); err != nil {

lib/ignore/ignore_test.go

@@ -10,7 +10,6 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -232,7 +231,7 @@ func TestCaseSensitivity(t *testing.T) {
 }
 
 func TestCaching(t *testing.T) {
-	dir, err := ioutil.TempDir("", "")
+	dir, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -425,7 +424,7 @@ flamingo
 *.crow
 	`
 	// Caches per file, hence write the patterns to a file.
-	dir, err := ioutil.TempDir("", "")
+	dir, err := os.MkdirTemp("", "")
 	if err != nil {
 		b.Fatal(err)
 	}
@@ -466,7 +465,7 @@ flamingo
 }
 
 func TestCacheReload(t *testing.T) {
-	dir, err := ioutil.TempDir("", "")
+	dir, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -989,7 +988,7 @@ func TestIssue4689(t *testing.T) {
 }
 
 func TestIssue4901(t *testing.T) {
-	dir, err := ioutil.TempDir("", "")
+	dir, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1001,7 +1000,7 @@ func TestIssue4901(t *testing.T) {
 	puppy
 	`
 
-	if err := ioutil.WriteFile(filepath.Join(dir, ".stignore"), []byte(stignore), 0777); err != nil {
+	if err := os.WriteFile(filepath.Join(dir, ".stignore"), []byte(stignore), 0777); err != nil {
 		t.Fatalf(err.Error())
 	}
 
@@ -1020,7 +1019,7 @@ func TestIssue4901(t *testing.T) {
 		}
 	}
 
-	if err := ioutil.WriteFile(filepath.Join(dir, "unicorn-lazor-death"), []byte(" "), 0777); err != nil {
+	if err := os.WriteFile(filepath.Join(dir, "unicorn-lazor-death"), []byte(" "), 0777); err != nil {
 		t.Fatalf(err.Error())
 	}
 
@@ -1193,3 +1192,42 @@ func TestEmptyPatterns(t *testing.T) {
 		}
 	}
 }
+
+func TestWindowsLineEndings(t *testing.T) {
+	if runtime.GOOS != "windows" {
+		t.Skip("Windows specific")
+	}
+
+	lines := "foo\nbar\nbaz\n"
+
+	dir, err := os.MkdirTemp("", "syncthing-test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+
+	ffs := fs.NewFilesystem(fs.FilesystemTypeBasic, dir)
+	m := New(ffs)
+	if err := m.Parse(strings.NewReader(lines), ".stignore"); err != nil {
+		t.Fatal(err)
+	}
+	if err := WriteIgnores(ffs, ".stignore", m.Lines()); err != nil {
+		t.Fatal(err)
+	}
+
+	fd, err := ffs.Open(".stignore")
+	if err != nil {
+		t.Fatal(err)
+	}
+	bs, err := io.ReadAll(fd)
+	fd.Close()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	unixLineEndings := bytes.Count(bs, []byte("\n"))
+	windowsLineEndings := bytes.Count(bs, []byte("\r\n"))
+	if unixLineEndings == 0 || windowsLineEndings != unixLineEndings {
+		t.Error("expected there to be a non-zero number of Windows line endings")
+	}
+}

lib/logger/logger.go

@@ -10,7 +10,6 @@ package logger
 import (
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"strings"
@@ -75,7 +74,7 @@ func New() Logger {
 	if os.Getenv("LOGGER_DISCARD") != "" {
 		// Hack to completely disable logging, for example when running
 		// benchmarks.
-		return newLogger(ioutil.Discard)
+		return newLogger(io.Discard)
 	}
 	return newLogger(controlStripper{os.Stdout})
 }

lib/logger/logger_test.go

@@ -6,7 +6,7 @@ package logger
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"log"
 	"strings"
 	"testing"
@@ -186,12 +186,12 @@ func TestControlStripper(t *testing.T) {
 }
 
 func BenchmarkLog(b *testing.B) {
-	l := newLogger(controlStripper{ioutil.Discard})
+	l := newLogger(controlStripper{io.Discard})
 	benchmarkLogger(b, l)
 }
 
 func BenchmarkLogNoStripper(b *testing.B) {
-	l := newLogger(ioutil.Discard)
+	l := newLogger(io.Discard)
 	benchmarkLogger(b, l)
 }
 

lib/model/deviceactivity.go

@@ -26,20 +26,19 @@ func newDeviceActivity() *deviceActivity {
 	}
 }
 
-func (m *deviceActivity) leastBusy(availability []Availability) (Availability, bool) {
+// Returns the index of the least busy device, or -1 if all are too busy.
+func (m *deviceActivity) leastBusy(availability []Availability) int {
 	m.mut.Lock()
 	low := 2<<30 - 1
-	found := false
-	var selected Availability
-	for _, info := range availability {
-		if usage := m.act[info.ID]; usage < low {
+	best := -1
+	for i := range availability {
+		if usage := m.act[availability[i].ID]; usage < low {
 			low = usage
-			selected = info
-			found = true
+			best = i
 		}
 	}
 	m.mut.Unlock()
-	return selected, found
+	return best
 }
 
 func (m *deviceActivity) using(availability Availability) {

lib/model/deviceactivity_test.go

@@ -19,42 +19,42 @@ func TestDeviceActivity(t *testing.T) {
 	devices := []Availability{n0, n1, n2}
 	na := newDeviceActivity()
 
-	if lb, ok := na.leastBusy(devices); !ok || lb != n0 {
+	if lb := na.leastBusy(devices); lb != 0 {
 		t.Errorf("Least busy device should be n0 (%v) not %v", n0, lb)
 	}
-	if lb, ok := na.leastBusy(devices); !ok || lb != n0 {
+	if lb := na.leastBusy(devices); lb != 0 {
 		t.Errorf("Least busy device should still be n0 (%v) not %v", n0, lb)
 	}
 
-	lb, _ := na.leastBusy(devices)
-	na.using(lb)
-	if lb, ok := na.leastBusy(devices); !ok || lb != n1 {
+	lb := na.leastBusy(devices)
+	na.using(devices[lb])
+	if lb := na.leastBusy(devices); lb != 1 {
 		t.Errorf("Least busy device should be n1 (%v) not %v", n1, lb)
 	}
-	lb, _ = na.leastBusy(devices)
-	na.using(lb)
-	if lb, ok := na.leastBusy(devices); !ok || lb != n2 {
+	lb = na.leastBusy(devices)
+	na.using(devices[lb])
+	if lb := na.leastBusy(devices); lb != 2 {
 		t.Errorf("Least busy device should be n2 (%v) not %v", n2, lb)
 	}
 
-	lb, _ = na.leastBusy(devices)
-	na.using(lb)
-	if lb, ok := na.leastBusy(devices); !ok || lb != n0 {
+	lb = na.leastBusy(devices)
+	na.using(devices[lb])
+	if lb := na.leastBusy(devices); lb != 0 {
 		t.Errorf("Least busy device should be n0 (%v) not %v", n0, lb)
 	}
 
 	na.done(n1)
-	if lb, ok := na.leastBusy(devices); !ok || lb != n1 {
+	if lb := na.leastBusy(devices); lb != 1 {
 		t.Errorf("Least busy device should be n1 (%v) not %v", n1, lb)
 	}
 
 	na.done(n2)
-	if lb, ok := na.leastBusy(devices); !ok || lb != n1 {
+	if lb := na.leastBusy(devices); lb != 1 {
 		t.Errorf("Least busy device should still be n1 (%v) not %v", n1, lb)
 	}
 
 	na.done(n0)
-	if lb, ok := na.leastBusy(devices); !ok || lb != n0 {
+	if lb := na.leastBusy(devices); lb != 0 {
 		t.Errorf("Least busy device should be n0 (%v) not %v", n0, lb)
 	}
 }

lib/model/folder_recvonly.go

@@ -68,7 +68,7 @@ func (f *receiveOnlyFolder) Revert() {
 }
 
 func (f *receiveOnlyFolder) revert() error {
-	l.Infof("Reverting folder %v", f.Description)
+	l.Infof("Reverting folder %v", f.Description())
 
 	f.setState(FolderScanning)
 	defer f.setState(FolderIdle)

lib/model/folder_sendrecv.go

@@ -1532,8 +1532,8 @@ loop:
 		// Select the least busy device to pull the block from. If we found no
 		// feasible device at all, fail the block (and in the long run, the
 		// file).
-		selected, found := activity.leastBusy(candidates)
-		if !found {
+		found := activity.leastBusy(candidates)
+		if found == -1 {
 			if lastError != nil {
 				state.fail(errors.Wrap(lastError, "pull"))
 			} else {
@@ -1542,7 +1542,9 @@ loop:
 			break
 		}
 
-		candidates = removeAvailability(candidates, selected)
+		selected := candidates[found]
+		candidates[found] = candidates[len(candidates)-1]
+		candidates = candidates[:len(candidates)-1]
 
 		// Fetch the block, while marking the selected device as in use so that
 		// leastBusy can select another device when someone else asks.
@@ -1804,16 +1806,6 @@ func (f *sendReceiveFolder) inConflict(current, replacement protocol.Vector) boo
 	return false
 }
 
-func removeAvailability(availabilities []Availability, availability Availability) []Availability {
-	for i := range availabilities {
-		if availabilities[i] == availability {
-			availabilities[i] = availabilities[len(availabilities)-1]
-			return availabilities[:len(availabilities)-1]
-		}
-	}
-	return availabilities
-}
-
 func (f *sendReceiveFolder) moveForConflict(name, lastModBy string, scanChan chan<- string) error {
 	if isConflict(name) {
 		l.Infoln("Conflict for", name, "which is already a conflict copy; not copying again.")

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/folder_summary.go

@@ -178,7 +178,11 @@ func (c *folderSummaryService) listenForUpdates(ctx context.Context) error {
 		// This loop needs to be fast so we don't miss too many events.
 
 		select {
-		case ev := <-sub.C():
+		case ev, ok := <-sub.C():
+			if !ok {
+				<-ctx.Done()
+				return ctx.Err()
+			}
 			c.processUpdate(ev)
 		case <-ctx.Done():
 			return ctx.Err()

lib/model/model.go

@@ -168,6 +168,8 @@ type model struct {
 	foldersRunning int32
 }
 
+var _ config.Verifier = &model{}
+
 type folderFactory func(*model, *db.FileSet, *ignore.Matcher, config.FolderConfiguration, versioner.Versioner, events.Logger, *util.Semaphore) service
 
 var (

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/progressemitter.go

@@ -212,11 +212,6 @@ func (t *ProgressEmitter) computeProgressUpdates() []progressUpdate {
 	return progressUpdates
 }
 
-// VerifyConfiguration implements the config.Committer interface
-func (t *ProgressEmitter) VerifyConfiguration(from, to config.Configuration) error {
-	return nil
-}
-
 // CommitConfiguration implements the config.Committer interface
 func (t *ProgressEmitter) CommitConfiguration(_, to config.Configuration) bool {
 	t.mut.Lock()

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")
 	}

lib/nat/service.go

@@ -45,10 +45,6 @@ func NewService(id protocol.DeviceID, cfg config.Wrapper) *Service {
 	return s
 }
 
-func (s *Service) VerifyConfiguration(from, to config.Configuration) error {
-	return nil
-}
-
 func (s *Service) CommitConfiguration(from, to config.Configuration) bool {
 	s.mut.Lock()
 	if !s.enabled && to.Options.NATEnabled {
@@ -125,11 +121,15 @@ func (s *Service) process(ctx context.Context) (int, time.Duration) {
 
 	s.mut.RLock()
 	for _, mapping := range s.mappings {
-		if mapping.expires.Before(time.Now()) {
+		mapping.mut.RLock()
+		expires := mapping.expires
+		mapping.mut.RUnlock()
+
+		if expires.Before(time.Now()) {
 			toRenew = append(toRenew, mapping)
 		} else {
 			toUpdate = append(toUpdate, mapping)
-			mappingRenewIn := time.Until(mapping.expires)
+			mappingRenewIn := time.Until(expires)
 			if mappingRenewIn < renewIn {
 				renewIn = mappingRenewIn
 			}
@@ -206,41 +206,36 @@ func (s *Service) RemoveMapping(mapping *Mapping) {
 // Optionally takes renew flag which indicates whether or not we should renew
 // mappings with existing natds
 func (s *Service) updateMapping(ctx context.Context, mapping *Mapping, nats map[string]Device, renew bool) {
-	var added, removed []Address
-
 	renewalTime := time.Duration(s.cfg.Options().NATRenewalM) * time.Minute
+
+	mapping.mut.Lock()
+
 	mapping.expires = time.Now().Add(renewalTime)
+	change := s.verifyExistingLocked(ctx, mapping, nats, renew)
+	add := s.acquireNewLocked(ctx, mapping, nats)
 
-	newAdded, newRemoved := s.verifyExistingMappings(ctx, mapping, nats, renew)
-	added = append(added, newAdded...)
-	removed = append(removed, newRemoved...)
+	mapping.mut.Unlock()
 
-	newAdded, newRemoved = s.acquireNewMappings(ctx, mapping, nats)
-	added = append(added, newAdded...)
-	removed = append(removed, newRemoved...)
-
-	if len(added) > 0 || len(removed) > 0 {
-		mapping.notify(added, removed)
+	if change || add {
+		mapping.notify()
 	}
 }
 
-func (s *Service) verifyExistingMappings(ctx context.Context, mapping *Mapping, nats map[string]Device, renew bool) ([]Address, []Address) {
-	var added, removed []Address
-
+func (s *Service) verifyExistingLocked(ctx context.Context, mapping *Mapping, nats map[string]Device, renew bool) (change bool) {
 	leaseTime := time.Duration(s.cfg.Options().NATLeaseM) * time.Minute
 
-	for id, address := range mapping.addressMap() {
+	for id, address := range mapping.extAddresses {
 		select {
 		case <-ctx.Done():
-			return nil, nil
+			return false
 		default:
 		}
 
 		// Delete addresses for NATDevice's that do not exist anymore
 		nat, ok := nats[id]
 		if !ok {
-			mapping.removeAddress(id)
-			removed = append(removed, address)
+			mapping.removeAddressLocked(id)
+			change = true
 			continue
 		} else if renew {
 			// Only perform renewals on the nat's that have the right local IP
@@ -256,35 +251,32 @@ func (s *Service) verifyExistingMappings(ctx context.Context, mapping *Mapping,
 			addr, err := s.tryNATDevice(ctx, nat, mapping.address.Port, address.Port, leaseTime)
 			if err != nil {
 				l.Debugf("Failed to renew %s -> mapping on %s", mapping, address, id)
-				mapping.removeAddress(id)
-				removed = append(removed, address)
+				mapping.removeAddressLocked(id)
+				change = true
 				continue
 			}
 
 			l.Debugf("Renewed %s -> %s mapping on %s", mapping, address, id)
 
 			if !addr.Equal(address) {
-				mapping.removeAddress(id)
-				mapping.setAddress(id, addr)
-				removed = append(removed, address)
-				added = append(added, address)
+				mapping.removeAddressLocked(id)
+				mapping.setAddressLocked(id, addr)
+				change = true
 			}
 		}
 	}
 
-	return added, removed
+	return change
 }
 
-func (s *Service) acquireNewMappings(ctx context.Context, mapping *Mapping, nats map[string]Device) ([]Address, []Address) {
-	var added, removed []Address
-
+func (s *Service) acquireNewLocked(ctx context.Context, mapping *Mapping, nats map[string]Device) (change bool) {
 	leaseTime := time.Duration(s.cfg.Options().NATLeaseM) * time.Minute
-	addrMap := mapping.addressMap()
+	addrMap := mapping.extAddresses
 
 	for id, nat := range nats {
 		select {
 		case <-ctx.Done():
-			return nil, nil
+			return false
 		default:
 		}
 
@@ -310,11 +302,11 @@ func (s *Service) acquireNewMappings(ctx context.Context, mapping *Mapping, nats
 
 		l.Debugf("Acquired %s -> %s mapping on %s", mapping, addr, id)
 
-		mapping.setAddress(id, addr)
-		added = append(added, addr)
+		mapping.setAddressLocked(id, addr)
+		change = true
 	}
 
-	return added, removed
+	return change
 }
 
 // tryNATDevice tries to acquire a port mapping for the given internal address to

lib/nat/structs.go

@@ -14,7 +14,7 @@ import (
 	"github.com/syncthing/syncthing/lib/sync"
 )
 
-type MappingChangeSubscriber func(*Mapping, []Address, []Address)
+type MappingChangeSubscriber func()
 
 type Mapping struct {
 	protocol Protocol
@@ -26,55 +26,41 @@ type Mapping struct {
 	mut          sync.RWMutex
 }
 
-func (m *Mapping) setAddress(id string, address Address) {
-	m.mut.Lock()
-	if existing, ok := m.extAddresses[id]; !ok || !existing.Equal(address) {
-		l.Infof("New NAT port mapping: external %s address %s to local address %s.", m.protocol, address, m.address)
-		m.extAddresses[id] = address
-	}
-	m.mut.Unlock()
+func (m *Mapping) setAddressLocked(id string, address Address) {
+	l.Infof("New NAT port mapping: external %s address %s to local address %s.", m.protocol, address, m.address)
+	m.extAddresses[id] = address
 }
 
-func (m *Mapping) removeAddress(id string) {
-	m.mut.Lock()
+func (m *Mapping) removeAddressLocked(id string) {
 	addr, ok := m.extAddresses[id]
 	if ok {
 		l.Infof("Removing NAT port mapping: external %s address %s, NAT %s is no longer available.", m.protocol, addr, id)
 		delete(m.extAddresses, id)
 	}
-	m.mut.Unlock()
 }
 
 func (m *Mapping) clearAddresses() {
 	m.mut.Lock()
-	var removed []Address
+	change := len(m.extAddresses) > 0
 	for id, addr := range m.extAddresses {
 		l.Debugf("Clearing mapping %s: ID: %s Address: %s", m, id, addr)
-		removed = append(removed, addr)
 		delete(m.extAddresses, id)
 	}
 	m.expires = time.Time{}
 	m.mut.Unlock()
-	if len(removed) > 0 {
-		m.notify(nil, removed)
+	if change {
+		m.notify()
 	}
 }
 
-func (m *Mapping) notify(added, removed []Address) {
+func (m *Mapping) notify() {
 	m.mut.RLock()
 	for _, subscriber := range m.subscribers {
-		subscriber(m, added, removed)
+		subscriber()
 	}
 	m.mut.RUnlock()
 }
 
-func (m *Mapping) addressMap() map[string]Address {
-	m.mut.RLock()
-	addrMap := m.extAddresses
-	m.mut.RUnlock()
-	return addrMap
-}
-
 func (m *Mapping) Protocol() Protocol {
 	return m.protocol
 }

lib/nat/structs_test.go

@@ -7,7 +7,6 @@
 package nat
 
 import (
-	"io/ioutil"
 	"net"
 	"os"
 	"testing"
@@ -60,7 +59,7 @@ func TestMappingValidGateway(t *testing.T) {
 }
 
 func TestMappingClearAddresses(t *testing.T) {
-	tmpFile, err := ioutil.TempFile("", "syncthing-testConfig-")
+	tmpFile, err := os.CreateTemp("", "syncthing-testConfig-")
 	if err != nil {
 		t.Fatal(err)
 	}

lib/osutil/atomic.go

@@ -43,7 +43,7 @@ func CreateAtomic(path string) (*AtomicWriter, error) {
 // permissions.
 func CreateAtomicFilesystem(filesystem fs.Filesystem, path string) (*AtomicWriter, error) {
 	// The security of this depends on the tempfile having secure
-	// permissions, 0600, from the beginning. This is what ioutil.TempFile
+	// permissions, 0600, from the beginning. This is what os.CreateTemp
 	// does. We have a test that verifies that that is the case, should this
 	// ever change in the standard library in the future.
 	fd, err := TempFile(filesystem, filepath.Dir(path), TempPrefix)

lib/osutil/atomic_test.go

@@ -8,7 +8,6 @@ package osutil
 
 import (
 	"bytes"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -35,7 +34,7 @@ func TestCreateAtomicCreate(t *testing.T) {
 		t.Fatal("written bytes", n, "!= 5")
 	}
 
-	if _, err := ioutil.ReadFile("testdata/file"); err == nil {
+	if _, err := os.ReadFile("testdata/file"); err == nil {
 		t.Fatal("file should not exist")
 	}
 
@@ -43,7 +42,7 @@ func TestCreateAtomicCreate(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	bs, err := ioutil.ReadFile("testdata/file")
+	bs, err := os.ReadFile("testdata/file")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -62,7 +61,7 @@ func TestCreateAtomicReplaceReadOnly(t *testing.T) {
 func testCreateAtomicReplace(t *testing.T, oldPerms os.FileMode) {
 	t.Helper()
 
-	testdir, err := ioutil.TempDir("", "syncthing")
+	testdir, err := os.MkdirTemp("", "syncthing")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -75,7 +74,7 @@ func testCreateAtomicReplace(t *testing.T, oldPerms os.FileMode) {
 		t.Fatal(err)
 	}
 
-	if err := ioutil.WriteFile(testfile, []byte("some old data"), oldPerms); err != nil {
+	if err := os.WriteFile(testfile, []byte("some old data"), oldPerms); err != nil {
 		t.Fatal(err)
 	}
 
@@ -103,7 +102,7 @@ func testCreateAtomicReplace(t *testing.T, oldPerms os.FileMode) {
 		t.Fatal(err)
 	}
 
-	bs, err := ioutil.ReadFile(testfile)
+	bs, err := os.ReadFile(testfile)
 	if err != nil {
 		t.Fatal(err)
 	}

lib/osutil/atomic_unix_test.go

@@ -12,7 +12,6 @@
 package osutil
 
 import (
-	"io/ioutil"
 	"os"
 	"syscall"
 	"testing"
@@ -24,7 +23,7 @@ func TestTempFilePermissions(t *testing.T) {
 	oldMask := syscall.Umask(0)
 	defer syscall.Umask(oldMask)
 
-	fd, err := ioutil.TempFile("", "test")
+	fd, err := os.CreateTemp("", "test")
 	if err != nil {
 		t.Fatal(err)
 	}

lib/osutil/lowprio_windows.go

@@ -7,43 +7,19 @@
 package osutil
 
 import (
-	"syscall"
-
 	"github.com/pkg/errors"
-)
-
-const (
-	// https://docs.microsoft.com/windows/win32/api/processthreadsapi/nf-processthreadsapi-setpriorityclass
-	aboveNormalPriorityClass   = 0x00008000
-	belowNormalPriorityClass   = 0x00004000
-	highPriorityClass          = 0x00000080
-	idlePriorityClass          = 0x00000040
-	normalPriorityClass        = 0x00000020
-	processModeBackgroundBegin = 0x00100000
-	processModeBackgroundEnd   = 0x00200000
-	realtimePriorityClass      = 0x00000100
+	"golang.org/x/sys/windows"
 )
 
 // SetLowPriority lowers the process CPU scheduling priority, and possibly
 // I/O priority depending on the platform and OS.
 func SetLowPriority() error {
-	modkernel32 := syscall.NewLazyDLL("kernel32.dll")
-	setPriorityClass := modkernel32.NewProc("SetPriorityClass")
-
-	if err := setPriorityClass.Find(); err != nil {
-		return errors.Wrap(err, "find proc")
-	}
-
-	handle, err := syscall.GetCurrentProcess()
+	handle, err := windows.GetCurrentProcess()
 	if err != nil {
-		return errors.Wrap(err, "get process handler")
+		return errors.Wrap(err, "get process handle")
 	}
-	defer syscall.CloseHandle(handle)
+	defer windows.CloseHandle(handle)
 
-	res, _, err := setPriorityClass.Call(uintptr(handle), belowNormalPriorityClass)
-	if res != 0 {
-		// "If the function succeeds, the return value is nonzero."
-		return nil
-	}
+	err = windows.SetPriorityClass(handle, windows.BELOW_NORMAL_PRIORITY_CLASS)
 	return errors.Wrap(err, "set priority class") // wraps nil as nil
 }

lib/osutil/osutil_test.go

@@ -7,7 +7,7 @@
 package osutil_test
 
 import (
-	"io/ioutil"
+	"io"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -83,7 +83,7 @@ func TestIsDeleted(t *testing.T) {
 func TestRenameOrCopy(t *testing.T) {
 	mustTempDir := func() string {
 		t.Helper()
-		tmpDir, err := ioutil.TempDir("", "")
+		tmpDir, err := os.MkdirTemp("", "")
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -131,7 +131,7 @@ func TestRenameOrCopy(t *testing.T) {
 			if err != nil {
 				t.Fatal(err)
 			}
-			buf, err := ioutil.ReadAll(fd)
+			buf, err := io.ReadAll(fd)
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -147,7 +147,7 @@ func TestRenameOrCopy(t *testing.T) {
 		if fd, err := test.dst.Open("new"); err != nil {
 			t.Fatal(err)
 		} else {
-			if buf, err := ioutil.ReadAll(fd); err != nil {
+			if buf, err := io.ReadAll(fd); err != nil {
 				t.Fatal(err)
 			} else if string(buf) != content {
 				t.Fatalf("expected %s got %s", content, string(buf))

lib/osutil/replacingwriter.go

@@ -9,6 +9,7 @@ package osutil
 import (
 	"bytes"
 	"io"
+	"runtime"
 )
 
 type ReplacingWriter struct {
@@ -46,3 +47,16 @@ func (w ReplacingWriter) Write(bs []byte) (int, error) {
 
 	return written, err
 }
+
+// LineEndingsWriter returns a writer that writes platform-appropriate line
+// endings. (This is a no-op on non-Windows platforms.)
+func LineEndingsWriter(w io.Writer) io.Writer {
+	if runtime.GOOS != "windows" {
+		return w
+	}
+	return &ReplacingWriter{
+		Writer: w,
+		From:   '\n',
+		To:     []byte{'\r', '\n'},
+	}
+}

lib/osutil/traversessymlink_test.go

@@ -7,7 +7,6 @@
 package osutil_test
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -18,7 +17,7 @@ import (
 )
 
 func TestTraversesSymlink(t *testing.T) {
-	tmpDir, err := ioutil.TempDir(".", ".test-TraversesSymlink-")
+	tmpDir, err := os.MkdirTemp(".", ".test-TraversesSymlink-")
 	if err != nil {
 		panic("Failed to create temporary testing dir")
 	}
@@ -71,7 +70,7 @@ func TestTraversesSymlink(t *testing.T) {
 }
 
 func TestIssue4875(t *testing.T) {
-	tmpDir, err := ioutil.TempDir("", ".test-Issue4875-")
+	tmpDir, err := os.MkdirTemp("", ".test-Issue4875-")
 	if err != nil {
 		panic("Failed to create temporary testing dir")
 	}

lib/protocol/deviceid.go

@@ -214,18 +214,3 @@ func untypeoify(s string) string {
 	s = strings.ReplaceAll(s, "8", "B")
 	return s
 }
-
-// DeviceIDs is a sortable slice of DeviceID
-type DeviceIDs []DeviceID
-
-func (l DeviceIDs) Len() int {
-	return len(l)
-}
-
-func (l DeviceIDs) Less(a, b int) bool {
-	return l[a].Compare(l[b]) == -1
-}
-
-func (l DeviceIDs) Swap(a, b int) {
-	l[a], l[b] = l[b], l[a]
-}

lib/protocol/protocol_test.go

@@ -10,7 +10,7 @@ import (
 	"encoding/json"
 	"errors"
 	"io"
-	"io/ioutil"
+	"os"
 	"runtime"
 	"sync"
 	"testing"
@@ -432,8 +432,8 @@ func testMarshal(t *testing.T, prefix string, m1, m2 message) bool {
 	bs1, _ := json.MarshalIndent(m1, "", "  ")
 	bs2, _ := json.MarshalIndent(m2, "", "  ")
 	if !bytes.Equal(bs1, bs2) {
-		ioutil.WriteFile(prefix+"-1.txt", bs1, 0644)
-		ioutil.WriteFile(prefix+"-2.txt", bs2, 0644)
+		os.WriteFile(prefix+"-1.txt", bs1, 0644)
+		os.WriteFile(prefix+"-2.txt", bs2, 0644)
 		return false
 	}
 

lib/rc/rc.go

@@ -14,7 +14,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"net/http"
 	"net/url"
@@ -393,7 +392,7 @@ func (p *Process) Model(folder string) (Model, error) {
 }
 
 func (p *Process) readResponse(resp *http.Response) ([]byte, error) {
-	bs, err := ioutil.ReadAll(resp.Body)
+	bs, err := io.ReadAll(resp.Body)
 	resp.Body.Close()
 	if err != nil {
 		return bs, err

lib/relay/client/static.go

@@ -141,7 +141,17 @@ func (c *staticClient) connect(ctx context.Context) error {
 		return err
 	}
 
-	conn := tls.Client(tcpConn, c.config)
+	// Copy the TLS config and set the server name we're connecting to. In
+	// many cases this will be an IP address, in which case it's a no-op. In
+	// other cases it will be a hostname, which will cause the TLS stack to
+	// send SNI.
+	cfg := c.config
+	if host, _, err := net.SplitHostPort(c.uri.Host); err == nil {
+		cfg = cfg.Clone()
+		cfg.ServerName = host
+	}
+
+	conn := tls.Client(tcpConn, cfg)
 
 	if err := conn.SetDeadline(time.Now().Add(c.connectTimeout)); err != nil {
 		conn.Close()

lib/scanner/walk_test.go

@@ -13,7 +13,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -376,7 +375,7 @@ func TestWalkSymlinkWindows(t *testing.T) {
 
 func TestWalkRootSymlink(t *testing.T) {
 	// Create a folder with a symlink in it
-	tmp, err := ioutil.TempDir("", "")
+	tmp, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -709,7 +708,7 @@ func TestStopWalk(t *testing.T) {
 }
 
 func TestIssue4799(t *testing.T) {
-	tmp, err := ioutil.TempDir("", "")
+	tmp, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -771,7 +770,7 @@ func TestRecurseInclude(t *testing.T) {
 }
 
 func TestIssue4841(t *testing.T) {
-	tmp, err := ioutil.TempDir("", "")
+	tmp, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatal(err)
 	}

lib/sync/sync.go

@@ -19,11 +19,7 @@ import (
 	"github.com/sasha-s/go-deadlock"
 )
 
-type clock interface {
-	Now() time.Time
-}
-
-var defaultClock clock = (*standardClock)(nil)
+var timeNow = time.Now
 
 type Mutex interface {
 	Lock()
@@ -86,7 +82,7 @@ func (h holder) String() string {
 	if h.at == "" {
 		return "not held"
 	}
-	return fmt.Sprintf("at %s goid: %d for %s", h.at, h.goid, defaultClock.Now().Sub(h.time))
+	return fmt.Sprintf("at %s goid: %d for %s", h.at, h.goid, timeNow().Sub(h.time))
 }
 
 type loggedMutex struct {
@@ -101,7 +97,7 @@ func (m *loggedMutex) Lock() {
 
 func (m *loggedMutex) Unlock() {
 	currentHolder := m.holder.Load().(holder)
-	duration := defaultClock.Now().Sub(currentHolder.time)
+	duration := timeNow().Sub(currentHolder.time)
 	if duration >= threshold {
 		l.Debugf("Mutex held for %v. Locked at %s unlocked at %s", duration, currentHolder.at, getHolder().at)
 	}
@@ -125,7 +121,7 @@ type loggedRWMutex struct {
 }
 
 func (m *loggedRWMutex) Lock() {
-	start := defaultClock.Now()
+	start := timeNow()
 
 	atomic.StoreInt32(&m.logUnlockers, 1)
 	m.RWMutex.Lock()
@@ -153,7 +149,7 @@ func (m *loggedRWMutex) Lock() {
 
 func (m *loggedRWMutex) Unlock() {
 	currentHolder := m.holder.Load().(holder)
-	duration := defaultClock.Now().Sub(currentHolder.time)
+	duration := timeNow().Sub(currentHolder.time)
 	if duration >= threshold {
 		l.Debugf("RWMutex held for %v. Locked at %s unlocked at %s", duration, currentHolder.at, getHolder().at)
 	}
@@ -205,9 +201,9 @@ type loggedWaitGroup struct {
 }
 
 func (wg *loggedWaitGroup) Wait() {
-	start := defaultClock.Now()
+	start := timeNow()
 	wg.WaitGroup.Wait()
-	duration := defaultClock.Now().Sub(start)
+	duration := timeNow().Sub(start)
 	if duration >= threshold {
 		l.Debugf("WaitGroup took %v at %s", duration, getHolder())
 	}
@@ -219,7 +215,7 @@ func getHolder() holder {
 	return holder{
 		at:   fmt.Sprintf("%s:%d", file, line),
 		goid: goid(),
-		time: defaultClock.Now(),
+		time: timeNow(),
 	}
 }
 
@@ -300,9 +296,3 @@ func (w *TimeoutCondWaiter) Wait() bool {
 func (w *TimeoutCondWaiter) Stop() {
 	w.timer.Stop()
 }
-
-type standardClock struct{}
-
-func (*standardClock) Now() time.Time {
-	return time.Now()
-}

lib/sync/sync_test.go

@@ -57,10 +57,10 @@ func TestTypes(t *testing.T) {
 }
 
 func TestMutex(t *testing.T) {
-	oldClock := defaultClock
+	oldClock := timeNow
 	clock := newTestClock()
-	defaultClock = clock
-	defer func() { defaultClock = oldClock }()
+	timeNow = clock.Now
+	defer func() { timeNow = oldClock }()
 
 	debug = true
 	l.SetDebug("sync", true)
@@ -97,10 +97,10 @@ func TestMutex(t *testing.T) {
 }
 
 func TestRWMutex(t *testing.T) {
-	oldClock := defaultClock
+	oldClock := timeNow
 	clock := newTestClock()
-	defaultClock = clock
-	defer func() { defaultClock = oldClock }()
+	timeNow = clock.Now
+	defer func() { timeNow = oldClock }()
 
 	debug = true
 	l.SetDebug("sync", true)
@@ -170,10 +170,10 @@ func TestRWMutex(t *testing.T) {
 }
 
 func TestWaitGroup(t *testing.T) {
-	oldClock := defaultClock
+	oldClock := timeNow
 	clock := newTestClock()
-	defaultClock = clock
-	defer func() { defaultClock = oldClock }()
+	timeNow = clock.Now
+	defer func() { timeNow = oldClock }()
 
 	debug = true
 	l.SetDebug("sync", true)

lib/syncthing/auditservice.go

@@ -38,7 +38,11 @@ func (s *auditService) Serve(ctx context.Context) error {
 
 	for {
 		select {
-		case ev := <-sub.C():
+		case ev, ok := <-sub.C():
+			if !ok {
+				<-ctx.Done()
+				return ctx.Err()
+			}
 			enc.Encode(ev)
 		case <-ctx.Done():
 			return ctx.Err()

lib/syncthing/syncthing_test.go

@@ -7,7 +7,6 @@
 package syncthing
 
 import (
-	"io/ioutil"
 	"os"
 	"testing"
 	"time"
@@ -22,7 +21,7 @@ import (
 
 func tempCfgFilename(t *testing.T) string {
 	t.Helper()
-	f, err := ioutil.TempFile("", "syncthing-testConfig-")
+	f, err := os.CreateTemp("", "syncthing-testConfig-")
 	if err != nil {
 		t.Fatal(err)
 	}

lib/syncthing/utils.go

@@ -10,7 +10,6 @@ import (
 	"crypto/tls"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 
 	"github.com/pkg/errors"
@@ -24,6 +23,29 @@ import (
 	"github.com/syncthing/syncthing/lib/tlsutil"
 )
 
+func EnsureDir(dir string, mode fs.FileMode) error {
+	fs := fs.NewFilesystem(fs.FilesystemTypeBasic, dir)
+	err := fs.MkdirAll(".", mode)
+	if err != nil {
+		return err
+	}
+
+	if fi, err := fs.Stat("."); err == nil {
+		// Apprently the stat may fail even though the mkdirall passed. If it
+		// does, we'll just assume things are in order and let other things
+		// fail (like loading or creating the config...).
+		currentMode := fi.Mode() & 0777
+		if currentMode != mode {
+			err := fs.Chmod(".", mode)
+			// This can fail on crappy filesystems, nothing we can do about it.
+			if err != nil {
+				l.Warnln(err)
+			}
+		}
+	}
+	return nil
+}
+
 func LoadOrGenerateCertificate(certFile, keyFile string) (tls.Certificate, error) {
 	cert, err := tls.LoadX509KeyPair(certFile, keyFile)
 	if err != nil {
@@ -110,12 +132,12 @@ func archiveAndSaveConfig(cfg config.Wrapper, originalVersion int) error {
 }
 
 func copyFile(src, dst string) error {
-	bs, err := ioutil.ReadFile(src)
+	bs, err := os.ReadFile(src)
 	if err != nil {
 		return err
 	}
 
-	if err := ioutil.WriteFile(dst, bs, 0600); err != nil {
+	if err := os.WriteFile(dst, bs, 0600); err != nil {
 		// Attempt to clean up
 		os.Remove(dst)
 		return err

lib/syncthing/verboseservice.go

@@ -31,7 +31,11 @@ func (s *verboseService) Serve(ctx context.Context) error {
 	defer sub.Unsubscribe()
 	for {
 		select {
-		case ev := <-sub.C():
+		case ev, ok := <-sub.C():
+			if !ok {
+				<-ctx.Done()
+				return ctx.Err()
+			}
 			formatted := s.formatEvent(ev)
 			if formatted != "" {
 				l.Verboseln(formatted)

lib/upgrade/upgrade_supported.go

@@ -19,7 +19,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"os"
 	"path"
@@ -284,7 +283,7 @@ func readTarGz(archiveName, dir string, r io.Reader) (string, error) {
 }
 
 func readZip(archiveName, dir string, r io.Reader) (string, error) {
-	body, err := ioutil.ReadAll(r)
+	body, err := io.ReadAll(r)
 	if err != nil {
 		return "", err
 	}
@@ -357,7 +356,7 @@ func archiveFileVisitor(dir string, tempFile *string, signature *[]byte, archive
 
 	case "release.sig":
 		l.Debugf("found signature %s", archivePath)
-		*signature, err = ioutil.ReadAll(io.LimitReader(filedata, maxSignatureSize))
+		*signature, err = io.ReadAll(io.LimitReader(filedata, maxSignatureSize))
 		if err != nil {
 			return err
 		}
@@ -392,7 +391,7 @@ func verifyUpgrade(archiveName, tempName string, sig []byte) error {
 	// multireader. This ensures that it is not only a bonafide syncthing
 	// binary, but it is also of exactly the platform and version we expect.
 
-	mr := io.MultiReader(bytes.NewBufferString(archiveName+"\n"), fd)
+	mr := io.MultiReader(strings.NewReader(archiveName+"\n"), fd)
 	err = signature.Verify(SigningKey, sig, mr)
 	fd.Close()
 
@@ -407,7 +406,7 @@ func verifyUpgrade(archiveName, tempName string, sig []byte) error {
 func writeBinary(dir string, inFile io.Reader) (filename string, err error) {
 	// Write the binary to a temporary file.
 
-	outFile, err := ioutil.TempFile(dir, "syncthing")
+	outFile, err := os.CreateTemp(dir, "syncthing")
 	if err != nil {
 		return "", err
 	}

lib/upnp/upnp.go

@@ -38,7 +38,7 @@ import (
 	"context"
 	"encoding/xml"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net"
 	"net/http"
 	"net/url"
@@ -467,7 +467,7 @@ func soapRequest(ctx context.Context, url, service, function, message string) ([
 		return resp, err
 	}
 
-	resp, _ = ioutil.ReadAll(r.Body)
+	resp, _ = io.ReadAll(r.Body)
 	l.Debugf("SOAP Response: %s\n\n%s\n\n", r.Status, resp)
 
 	r.Body.Close()

lib/ur/failurereporting.go

@@ -188,10 +188,6 @@ func (h *failureHandler) addReport(data FailureData, evTime time.Time) {
 	}
 }
 
-func (h *failureHandler) VerifyConfiguration(_, _ config.Configuration) error {
-	return nil
-}
-
 func (h *failureHandler) CommitConfiguration(from, to config.Configuration) bool {
 	if from.Options.CREnabled != to.Options.CREnabled || from.Options.CRURL != to.Options.CRURL {
 		h.optsChan <- to.Options

lib/ur/usage_report.go

@@ -390,10 +390,6 @@ func (s *Service) Serve(ctx context.Context) error {
 	}
 }
 
-func (s *Service) VerifyConfiguration(from, to config.Configuration) error {
-	return nil
-}
-
 func (s *Service) CommitConfiguration(from, to config.Configuration) bool {
 	if from.Options.URAccepted != to.Options.URAccepted || from.Options.URUniqueID != to.Options.URUniqueID || from.Options.URURL != to.Options.URURL {
 		select {

lib/versioner/external_test.go

@@ -7,7 +7,6 @@
 package versioner
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -85,7 +84,7 @@ func prepForRemoval(t *testing.T, file string) {
 	if err := os.MkdirAll(filepath.Dir(file), 0755); err != nil {
 		t.Fatal(err)
 	}
-	if err := ioutil.WriteFile(file, []byte("hello\n"), 0644); err != nil {
+	if err := os.WriteFile(file, []byte("hello\n"), 0644); err != nil {
 		t.Fatal(err)
 	}
 }

lib/versioner/simple_test.go

@@ -7,8 +7,8 @@
 package versioner
 
 import (
-	"io/ioutil"
 	"math"
+	"os"
 	"path/filepath"
 	"testing"
 	"time"
@@ -55,7 +55,7 @@ func TestSimpleVersioningVersionCount(t *testing.T) {
 		t.Skip("Test takes some time, skipping.")
 	}
 
-	dir, err := ioutil.TempDir("", "")
+	dir, err := os.MkdirTemp("", "")
 	//defer os.RemoveAll(dir)
 	if err != nil {
 		t.Error(err)

lib/versioner/staggered_test.go

@@ -7,7 +7,7 @@
 package versioner
 
 import (
-	"io/ioutil"
+	"os"
 	"path/filepath"
 	"sort"
 	"strconv"
@@ -133,11 +133,11 @@ func TestCreateVersionPath(t *testing.T) {
 	)
 
 	// Create a test dir and file
-	tmpDir, err := ioutil.TempDir("", "")
+	tmpDir, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatal(err)
 	}
-	if err := ioutil.WriteFile(filepath.Join(tmpDir, archiveFile), []byte("sup"), 0644); err != nil {
+	if err := os.WriteFile(filepath.Join(tmpDir, archiveFile), []byte("sup"), 0644); err != nil {
 		t.Fatal(err)
 	}
 

lib/versioner/trashcan_test.go

@@ -7,7 +7,8 @@
 package versioner
 
 import (
-	"io/ioutil"
+	"io"
+	"os"
 	"testing"
 	"time"
 
@@ -19,12 +20,12 @@ func TestTrashcanArchiveRestoreSwitcharoo(t *testing.T) {
 	// This tests that trashcan versioner restoration correctly archives existing file, because trashcan versioner
 	// files are untagged, archiving existing file to replace with a restored version technically should collide in
 	// in names.
-	tmpDir1, err := ioutil.TempDir("", "")
+	tmpDir1, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	tmpDir2, err := ioutil.TempDir("", "")
+	tmpDir2, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -105,7 +106,7 @@ func readFile(t *testing.T, filesystem fs.Filesystem, name string) string {
 		t.Fatal(err)
 	}
 	defer fd.Close()
-	buf, err := ioutil.ReadAll(fd)
+	buf, err := io.ReadAll(fd)
 	if err != nil {
 		t.Fatal(err)
 	}

lib/versioner/versioner_test.go

@@ -9,7 +9,6 @@ package versioner
 import (
 	"context"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -56,7 +55,7 @@ func TestVersionerCleanOut(t *testing.T) {
 			oldTime := time.Now().Add(-8 * 24 * time.Hour)
 			for file, shouldRemove := range testcases {
 				os.MkdirAll(filepath.Dir(file), 0777)
-				if err := ioutil.WriteFile(file, []byte("data"), 0644); err != nil {
+				if err := os.WriteFile(file, []byte("data"), 0644); err != nil {
 					t.Fatal(err)
 				}
 				if shouldRemove {

lib/watchaggregator/aggregator.go

@@ -162,8 +162,10 @@ func (a *aggregator) mainLoop(in <-chan fs.Event, out chan<- []string, cfg confi
 		select {
 		case event := <-in:
 			a.newEvent(event, inProgress)
-		case event := <-inProgressItemSubscription.C():
-			updateInProgressSet(event, inProgress)
+		case event, ok := <-inProgressItemSubscription.C():
+			if ok {
+				updateInProgressSet(event, inProgress)
+			}
 		case <-a.notifyTimer.C:
 			a.actOnTimer(out)
 		case interval := <-a.notifyTimerResetChan:
@@ -419,10 +421,6 @@ func (a *aggregator) String() string {
 	return fmt.Sprintf("aggregator/%s:", a.folderCfg.Description())
 }
 
-func (a *aggregator) VerifyConfiguration(from, to config.Configuration) error {
-	return nil
-}
-
 func (a *aggregator) CommitConfiguration(from, to config.Configuration) bool {
 	for _, folderCfg := range to.Folders {
 		if folderCfg.ID == a.folderID {

lib/weakhash/weakhash_test.go

@@ -13,7 +13,6 @@ import (
 	"bytes"
 	"context"
 	"io"
-	"io/ioutil"
 	"os"
 	"reflect"
 	"testing"
@@ -22,7 +21,7 @@ import (
 var payload = []byte("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz")
 
 func TestFinder(t *testing.T) {
-	f, err := ioutil.TempFile("", "")
+	f, err := os.CreateTemp("", "")
 	if err != nil {
 		t.Error(err)
 	}