Merge pull request #3273 from JoeKar/fix/save-atomically

save: Perform write process safe

cmd/micro/clean.go

@@ -3,8 +3,8 @@ package main
 import (
 	"bufio"
 	"encoding/gob"
+	"errors"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"sort"
@@ -12,6 +12,7 @@ import (
 
 	"github.com/zyedidia/micro/v2/internal/buffer"
 	"github.com/zyedidia/micro/v2/internal/config"
+	"github.com/zyedidia/micro/v2/internal/util"
 )
 
 func shouldContinue() bool {
@@ -39,7 +40,16 @@ func CleanConfig() {
 	}
 
 	fmt.Println("Cleaning default settings")
-	config.WriteSettings(filepath.Join(config.ConfigDir, "settings.json"))
+
+	settingsFile := filepath.Join(config.ConfigDir, "settings.json")
+	err := config.WriteSettings(settingsFile)
+	if err != nil {
+		if errors.Is(err, util.ErrOverwrite) {
+			fmt.Println(err.Error())
+		} else {
+			fmt.Println("Error writing settings.json file: " + err.Error())
+		}
+	}
 
 	// detect unused options
 	var unusedOptions []string
@@ -67,16 +77,20 @@ func CleanConfig() {
 			fmt.Printf("%s (value: %v)\n", s, config.GlobalSettings[s])
 		}
 
-		fmt.Printf("These options will be removed from %s\n", filepath.Join(config.ConfigDir, "settings.json"))
+		fmt.Printf("These options will be removed from %s\n", settingsFile)
 
 		if shouldContinue() {
 			for _, s := range unusedOptions {
 				delete(config.GlobalSettings, s)
 			}
 
-			err := config.OverwriteSettings(filepath.Join(config.ConfigDir, "settings.json"))
+			err := config.OverwriteSettings(settingsFile)
 			if err != nil {
-				fmt.Println("Error writing settings.json file: " + err.Error())
+				if errors.Is(err, util.ErrOverwrite) {
+					fmt.Println(err.Error())
+				} else {
+					fmt.Println("Error overwriting settings.json file: " + err.Error())
+				}
 			}
 
 			fmt.Println("Removed unused options")
@@ -85,12 +99,13 @@ func CleanConfig() {
 	}
 
 	// detect incorrectly formatted buffer/ files
-	files, err := ioutil.ReadDir(filepath.Join(config.ConfigDir, "buffers"))
+	buffersPath := filepath.Join(config.ConfigDir, "buffers")
+	files, err := os.ReadDir(buffersPath)
 	if err == nil {
 		var badFiles []string
 		var buffer buffer.SerializedBuffer
 		for _, f := range files {
-			fname := filepath.Join(config.ConfigDir, "buffers", f.Name())
+			fname := filepath.Join(buffersPath, f.Name())
 			file, e := os.Open(fname)
 
 			if e == nil {
@@ -105,9 +120,9 @@ func CleanConfig() {
 		}
 
 		if len(badFiles) > 0 {
-			fmt.Printf("Detected %d files with an invalid format in %s\n", len(badFiles), filepath.Join(config.ConfigDir, "buffers"))
+			fmt.Printf("Detected %d files with an invalid format in %s\n", len(badFiles), buffersPath)
 			fmt.Println("These files store cursor and undo history.")
-			fmt.Printf("Removing badly formatted files in %s\n", filepath.Join(config.ConfigDir, "buffers"))
+			fmt.Printf("Removing badly formatted files in %s\n", buffersPath)
 
 			if shouldContinue() {
 				removed := 0

cmd/micro/debug.go

@@ -18,7 +18,7 @@ func (NullWriter) Write(data []byte) (n int, err error) {
 // InitLog sets up the debug log system for micro if it has been enabled by compile-time variables
 func InitLog() {
 	if util.Debug == "ON" {
-		f, err := os.OpenFile("log.txt", os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0666)
+		f, err := os.OpenFile("log.txt", os.O_RDWR|os.O_CREATE|os.O_TRUNC, util.FileMode)
 		if err != nil {
 			log.Fatalf("error opening file: %v", err)
 		}

cmd/micro/micro.go

@@ -4,10 +4,10 @@ import (
 	"flag"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/signal"
+	"path/filepath"
 	"regexp"
 	"runtime"
 	"runtime/pprof"
@@ -99,7 +99,7 @@ func InitFlags() {
 		fmt.Println("Version:", util.Version)
 		fmt.Println("Commit hash:", util.CommitHash)
 		fmt.Println("Compiled on", util.CompileDate)
-		os.Exit(0)
+		exit(0)
 	}
 
 	if *flagOptions {
@@ -115,7 +115,7 @@ func InitFlags() {
 			fmt.Printf("-%s value\n", k)
 			fmt.Printf("    \tDefault value: '%v'\n", v)
 		}
-		os.Exit(0)
+		exit(0)
 	}
 
 	if util.Debug == "OFF" && *flagDebug {
@@ -136,7 +136,7 @@ func DoPluginFlags() {
 			CleanConfig()
 		}
 
-		os.Exit(0)
+		exit(0)
 	}
 }
 
@@ -209,7 +209,7 @@ func LoadInput(args []string) []*buffer.Buffer {
 		// Option 2
 		// The input is not a terminal, so something is being piped in
 		// and we should read from stdin
-		input, err = ioutil.ReadAll(os.Stdin)
+		input, err = io.ReadAll(os.Stdin)
 		if err != nil {
 			screen.TermMessage("Error reading from stdin: ", err)
 			input = []byte{}
@@ -223,12 +223,55 @@ func LoadInput(args []string) []*buffer.Buffer {
 	return buffers
 }
 
+func checkBackup(name string) error {
+	target := filepath.Join(config.ConfigDir, name)
+	backup := util.AppendBackupSuffix(target)
+	if info, err := os.Stat(backup); err == nil {
+		input, err := os.ReadFile(backup)
+		if err == nil {
+			t := info.ModTime()
+			msg := fmt.Sprintf(buffer.BackupMsg, target, t.Format("Mon Jan _2 at 15:04, 2006"), backup)
+			choice := screen.TermPrompt(msg, []string{"r", "i", "a", "recover", "ignore", "abort"}, true)
+
+			if choice%3 == 0 {
+				// recover
+				err := os.WriteFile(target, input, util.FileMode)
+				if err != nil {
+					return err
+				}
+				return os.Remove(backup)
+			} else if choice%3 == 1 {
+				// delete
+				return os.Remove(backup)
+			} else if choice%3 == 2 {
+				// abort
+				return errors.New("Aborted")
+			}
+		}
+	}
+	return nil
+}
+
+func exit(rc int) {
+	for _, b := range buffer.OpenBuffers {
+		if !b.Modified() {
+			b.Fini()
+		}
+	}
+
+	if screen.Screen != nil {
+		screen.Screen.Fini()
+	}
+
+	os.Exit(rc)
+}
+
 func main() {
 	defer func() {
 		if util.Stdout.Len() > 0 {
 			fmt.Fprint(os.Stdout, util.Stdout.String())
 		}
-		os.Exit(0)
+		exit(0)
 	}()
 
 	var err error
@@ -256,6 +299,12 @@ func main() {
 	config.InitRuntimeFiles(true)
 	config.InitPlugins()
 
+	err = checkBackup("settings.json")
+	if err != nil {
+		screen.TermMessage(err)
+		exit(1)
+	}
+
 	err = config.ReadSettings()
 	if err != nil {
 		screen.TermMessage(err)
@@ -288,7 +337,7 @@ func main() {
 	if err != nil {
 		fmt.Println(err)
 		fmt.Println("Fatal: Micro could not initialize a Screen.")
-		os.Exit(1)
+		exit(1)
 	}
 	m := clipboard.SetMethod(config.GetGlobalOption("clipboard").(string))
 	clipErr := clipboard.Initialize(m)
@@ -307,7 +356,7 @@ func main() {
 			for _, b := range buffer.OpenBuffers {
 				b.Backup()
 			}
-			os.Exit(1)
+			exit(1)
 		}
 	}()
 
@@ -316,6 +365,12 @@ func main() {
 		screen.TermMessage(err)
 	}
 
+	err = checkBackup("bindings.json")
+	if err != nil {
+		screen.TermMessage(err)
+		exit(1)
+	}
+
 	action.InitBindings()
 	action.InitCommands()
 
@@ -434,24 +489,12 @@ func DoEvent() {
 		}
 	case f := <-timerChan:
 		f()
+	case b := <-buffer.BackupCompleteChan:
+		b.RequestedBackup = false
 	case <-sighup:
-		for _, b := range buffer.OpenBuffers {
-			if !b.Modified() {
-				b.Fini()
-			}
-		}
-		os.Exit(0)
+		exit(0)
 	case <-util.Sigterm:
-		for _, b := range buffer.OpenBuffers {
-			if !b.Modified() {
-				b.Fini()
-			}
-		}
-
-		if screen.Screen != nil {
-			screen.Screen.Fini()
-		}
-		os.Exit(0)
+		exit(0)
 	}
 
 	if e, ok := event.(*tcell.EventError); ok {
@@ -459,16 +502,7 @@ func DoEvent() {
 
 		if e.Err() == io.EOF {
 			// shutdown due to terminal closing/becoming inaccessible
-			for _, b := range buffer.OpenBuffers {
-				if !b.Modified() {
-					b.Fini()
-				}
-			}
-
-			if screen.Screen != nil {
-				screen.Screen.Fini()
-			}
-			os.Exit(0)
+			exit(0)
 		}
 		return
 	}

internal/action/actions.go

@@ -1003,6 +1003,9 @@ func (h *BufPane) SaveAsCB(action string, callback func()) bool {
 						h.completeAction(action)
 						return
 					}
+				} else {
+					InfoBar.Error(err)
+					return
 				}
 			} else {
 				InfoBar.YNPrompt(
@@ -1039,7 +1042,6 @@ func (h *BufPane) saveBufToFile(filename string, action string, callback func())
 				if err != nil {
 					InfoBar.Error(err)
 				} else {
-					h.Buf.Path = filename
 					h.Buf.SetName(filename)
 					InfoBar.Message("Saved " + filename)
 					if callback != nil {
@@ -1065,7 +1067,6 @@ func (h *BufPane) saveBufToFile(filename string, action string, callback func())
 			InfoBar.Error(err)
 		}
 	} else {
-		h.Buf.Path = filename
 		h.Buf.SetName(filename)
 		InfoBar.Message("Saved " + filename)
 		if callback != nil {

internal/action/bindings.go

@@ -4,7 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"io/fs"
 	"os"
 	"path/filepath"
 	"regexp"
@@ -14,6 +14,7 @@ import (
 	"github.com/micro-editor/json5"
 	"github.com/zyedidia/micro/v2/internal/config"
 	"github.com/zyedidia/micro/v2/internal/screen"
+	"github.com/zyedidia/micro/v2/internal/util"
 	"github.com/micro-editor/tcell/v2"
 )
 
@@ -23,9 +24,13 @@ var Binder = map[string]func(e Event, action string){
 	"terminal": TermMapEvent,
 }
 
+func writeFile(name string, txt []byte) error {
+	return util.SafeWrite(name, txt, false)
+}
+
 func createBindingsIfNotExist(fname string) {
-	if _, e := os.Stat(fname); os.IsNotExist(e) {
-		ioutil.WriteFile(fname, []byte("{}"), 0644)
+	if _, e := os.Stat(fname); errors.Is(e, fs.ErrNotExist) {
+		writeFile(fname, []byte("{}"))
 	}
 }
 
@@ -37,7 +42,7 @@ func InitBindings() {
 	createBindingsIfNotExist(filename)
 
 	if _, e := os.Stat(filename); e == nil {
-		input, err := ioutil.ReadFile(filename)
+		input, err := os.ReadFile(filename)
 		if err != nil {
 			screen.TermMessage("Error reading bindings.json file: " + err.Error())
 			return
@@ -265,7 +270,7 @@ func TryBindKey(k, v string, overwrite bool) (bool, error) {
 	filename := filepath.Join(config.ConfigDir, "bindings.json")
 	createBindingsIfNotExist(filename)
 	if _, e = os.Stat(filename); e == nil {
-		input, err := ioutil.ReadFile(filename)
+		input, err := os.ReadFile(filename)
 		if err != nil {
 			return false, errors.New("Error reading bindings.json file: " + err.Error())
 		}
@@ -304,7 +309,8 @@ func TryBindKey(k, v string, overwrite bool) (bool, error) {
 		BindKey(k, v, Binder["buffer"])
 
 		txt, _ := json.MarshalIndent(parsed, "", "    ")
-		return true, ioutil.WriteFile(filename, append(txt, '\n'), 0644)
+		txt = append(txt, '\n')
+		return true, writeFile(filename, txt)
 	}
 	return false, e
 }
@@ -317,7 +323,7 @@ func UnbindKey(k string) error {
 	filename := filepath.Join(config.ConfigDir, "bindings.json")
 	createBindingsIfNotExist(filename)
 	if _, e = os.Stat(filename); e == nil {
-		input, err := ioutil.ReadFile(filename)
+		input, err := os.ReadFile(filename)
 		if err != nil {
 			return errors.New("Error reading bindings.json file: " + err.Error())
 		}
@@ -354,7 +360,8 @@ func UnbindKey(k string) error {
 		}
 
 		txt, _ := json.MarshalIndent(parsed, "", "    ")
-		return ioutil.WriteFile(filename, append(txt, '\n'), 0644)
+		txt = append(txt, '\n')
+		return writeFile(filename, txt)
 	}
 	return e
 }

internal/action/command.go

@@ -658,7 +658,16 @@ func SetGlobalOptionNative(option string, nativeValue interface{}) error {
 		delete(b.LocalSettings, option)
 	}
 
-	return config.WriteSettings(filepath.Join(config.ConfigDir, "settings.json"))
+	err := config.WriteSettings(filepath.Join(config.ConfigDir, "settings.json"))
+	if err != nil {
+		if errors.Is(err, util.ErrOverwrite) {
+			screen.TermMessage(err)
+			err = errors.Unwrap(err)
+		}
+		return err
+	}
+
+	return nil
 }
 
 func SetGlobalOption(option, value string) error {
@@ -783,7 +792,11 @@ func (h *BufPane) BindCmd(args []string) {
 
 	_, err := TryBindKey(parseKeyArg(args[0]), args[1], true)
 	if err != nil {
-		InfoBar.Error(err)
+		if errors.Is(err, util.ErrOverwrite) {
+			screen.TermMessage(err)
+		} else {
+			InfoBar.Error(err)
+		}
 	}
 }
 
@@ -796,7 +809,11 @@ func (h *BufPane) UnbindCmd(args []string) {
 
 	err := UnbindKey(parseKeyArg(args[0]))
 	if err != nil {
-		InfoBar.Error(err)
+		if errors.Is(err, util.ErrOverwrite) {
+			screen.TermMessage(err)
+		} else {
+			InfoBar.Error(err)
+		}
 	}
 }
 
@@ -890,7 +907,10 @@ func (h *BufPane) SaveCmd(args []string) {
 	if len(args) == 0 {
 		h.Save()
 	} else {
-		h.Buf.SaveAs(args[0])
+		err := h.Buf.SaveAs(args[0])
+		if err != nil {
+			InfoBar.Error(err)
+		}
 	}
 }
 

internal/buffer/autocomplete.go

@@ -2,7 +2,7 @@ package buffer
 
 import (
 	"bytes"
-	"io/ioutil"
+	"io/fs"
 	"os"
 	"sort"
 	"strings"
@@ -109,15 +109,15 @@ func FileComplete(b *Buffer) ([]string, []string) {
 	sep := string(os.PathSeparator)
 	dirs := strings.Split(input, sep)
 
-	var files []os.FileInfo
+	var files []fs.DirEntry
 	var err error
 	if len(dirs) > 1 {
 		directories := strings.Join(dirs[:len(dirs)-1], sep) + sep
 
 		directories, _ = util.ReplaceHome(directories)
-		files, err = ioutil.ReadDir(directories)
+		files, err = os.ReadDir(directories)
 	} else {
-		files, err = ioutil.ReadDir(".")
+		files, err = os.ReadDir(".")
 	}
 
 	if err != nil {

internal/buffer/backup.go

@@ -1,24 +1,26 @@
 package buffer
 
 import (
+	"errors"
 	"fmt"
-	"io"
+	"io/fs"
 	"os"
 	"path/filepath"
-	"sync/atomic"
-	"time"
 
 	"github.com/zyedidia/micro/v2/internal/config"
 	"github.com/zyedidia/micro/v2/internal/screen"
 	"github.com/zyedidia/micro/v2/internal/util"
-	"golang.org/x/text/encoding"
 )
 
-const backupMsg = `A backup was detected for this file. This likely means that micro
-crashed while editing this file, or another instance of micro is currently
-editing this file.
+const BackupMsg = `A backup was detected for:
 
-The backup was created on %s, and the file is
+%s
+
+This likely means that micro crashed while editing this file,
+or another instance of micro is currently editing this file,
+or an error occurred while saving this file so it may be corrupted.
+
+The backup was created on %s and its path is:
 
 %s
 
@@ -30,90 +32,80 @@ The backup was created on %s, and the file is
 
 Options: [r]ecover, [i]gnore, [a]bort: `
 
-var backupRequestChan chan *Buffer
+const backupSeconds = 8
 
-func backupThread() {
-	for {
-		time.Sleep(time.Second * 8)
-
-		for len(backupRequestChan) > 0 {
-			b := <-backupRequestChan
-			bfini := atomic.LoadInt32(&(b.fini)) != 0
-			if !bfini {
-				b.Backup()
-			}
-		}
-	}
-}
+var BackupCompleteChan chan *Buffer
 
 func init() {
-	backupRequestChan = make(chan *Buffer, 10)
-
-	go backupThread()
+	BackupCompleteChan = make(chan *Buffer, 10)
 }
 
 func (b *Buffer) RequestBackup() {
-	if !b.requestedBackup {
+	if !b.RequestedBackup {
 		select {
 		case backupRequestChan <- b:
 		default:
 			// channel is full
 		}
-		b.requestedBackup = true
+		b.RequestedBackup = true
 	}
 }
 
-// Backup saves the current buffer to ConfigDir/backups
+func (b *Buffer) backupDir() string {
+	backupdir, err := util.ReplaceHome(b.Settings["backupdir"].(string))
+	if backupdir == "" || err != nil {
+		backupdir = filepath.Join(config.ConfigDir, "backups")
+	}
+	return backupdir
+}
+
+func (b *Buffer) keepBackup() bool {
+	return b.forceKeepBackup || b.Settings["permbackup"].(bool)
+}
+
+// Backup saves the current buffer to the backups directory
 func (b *Buffer) Backup() error {
 	if !b.Settings["backup"].(bool) || b.Path == "" || b.Type != BTDefault {
 		return nil
 	}
 
-	backupdir, err := util.ReplaceHome(b.Settings["backupdir"].(string))
-	if backupdir == "" || err != nil {
-		backupdir = filepath.Join(config.ConfigDir, "backups")
-	}
-	if _, err := os.Stat(backupdir); os.IsNotExist(err) {
+	backupdir := b.backupDir()
+	if _, err := os.Stat(backupdir); errors.Is(err, fs.ErrNotExist) {
 		os.Mkdir(backupdir, os.ModePerm)
 	}
 
-	name := filepath.Join(backupdir, util.EscapePath(b.AbsPath))
-
-	err = overwriteFile(name, encoding.Nop, func(file io.Writer) (e error) {
-		if len(b.lines) == 0 {
-			return
+	name := util.DetermineEscapePath(backupdir, b.AbsPath)
+	if _, err := os.Stat(name); errors.Is(err, fs.ErrNotExist) {
+		_, err = b.overwriteFile(name)
+		if err == nil {
+			BackupCompleteChan <- b
 		}
+		return err
+	}
 
-		// end of line
-		eol := []byte{'\n'}
+	tmp := util.AppendBackupSuffix(name)
+	_, err := b.overwriteFile(tmp)
+	if err != nil {
+		os.Remove(tmp)
+		return err
+	}
+	err = os.Rename(tmp, name)
+	if err != nil {
+		os.Remove(tmp)
+		return err
+	}
 
-		// write lines
-		if _, e = file.Write(b.lines[0].data); e != nil {
-			return
-		}
-
-		for _, l := range b.lines[1:] {
-			if _, e = file.Write(eol); e != nil {
-				return
-			}
-			if _, e = file.Write(l.data); e != nil {
-				return
-			}
-		}
-		return
-	}, false)
-
-	b.requestedBackup = false
+	BackupCompleteChan <- b
 
 	return err
 }
 
 // RemoveBackup removes any backup file associated with this buffer
 func (b *Buffer) RemoveBackup() {
-	if !b.Settings["backup"].(bool) || b.Settings["permbackup"].(bool) || b.Path == "" || b.Type != BTDefault {
+	if !b.Settings["backup"].(bool) || b.keepBackup() || b.Path == "" || b.Type != BTDefault {
 		return
 	}
-	f := filepath.Join(config.ConfigDir, "backups", util.EscapePath(b.AbsPath))
+	f := util.DetermineEscapePath(b.backupDir(), b.AbsPath)
 	os.Remove(f)
 }
 
@@ -121,13 +113,13 @@ func (b *Buffer) RemoveBackup() {
 // Returns true if a backup was applied
 func (b *Buffer) ApplyBackup(fsize int64) (bool, bool) {
 	if b.Settings["backup"].(bool) && !b.Settings["permbackup"].(bool) && len(b.Path) > 0 && b.Type == BTDefault {
-		backupfile := filepath.Join(config.ConfigDir, "backups", util.EscapePath(b.AbsPath))
+		backupfile := util.DetermineEscapePath(b.backupDir(), b.AbsPath)
 		if info, err := os.Stat(backupfile); err == nil {
 			backup, err := os.Open(backupfile)
 			if err == nil {
 				defer backup.Close()
 				t := info.ModTime()
-				msg := fmt.Sprintf(backupMsg, t.Format("Mon Jan _2 at 15:04, 2006"), util.EscapePath(b.AbsPath))
+				msg := fmt.Sprintf(BackupMsg, b.Path, t.Format("Mon Jan _2 at 15:04, 2006"), backupfile)
 				choice := screen.TermPrompt(msg, []string{"r", "i", "a", "recover", "ignore", "abort"}, true)
 
 				if choice%3 == 0 {

internal/buffer/buffer.go

@@ -7,7 +7,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
+	"io/fs"
 	"os"
 	"path"
 	"path/filepath"
@@ -25,13 +25,12 @@ import (
 	"github.com/zyedidia/micro/v2/internal/screen"
 	"github.com/zyedidia/micro/v2/internal/util"
 	"github.com/zyedidia/micro/v2/pkg/highlight"
+	"golang.org/x/text/encoding"
 	"golang.org/x/text/encoding/htmlindex"
 	"golang.org/x/text/encoding/unicode"
 	"golang.org/x/text/transform"
 )
 
-const backupTime = 8000
-
 var (
 	// OpenBuffers is a list of the currently open buffers
 	OpenBuffers []*Buffer
@@ -89,6 +88,8 @@ type SharedBuffer struct {
 	// LocalSettings customized by the user for this buffer only
 	LocalSettings map[string]bool
 
+	encoding encoding.Encoding
+
 	Suggestions   []string
 	Completions   []string
 	CurSuggestion int
@@ -101,7 +102,8 @@ type SharedBuffer struct {
 	diffLock          sync.RWMutex
 	diff              map[int]DiffStatus
 
-	requestedBackup bool
+	RequestedBackup bool
+	forceKeepBackup bool
 
 	// ReloadDisabled allows the user to disable reloads if they
 	// are viewing a file that is constantly changing
@@ -237,17 +239,20 @@ func NewBufferFromFileAtLoc(path string, btype BufType, cursorLoc Loc) (*Buffer,
 		return nil, err
 	}
 
-	f, err := os.OpenFile(filename, os.O_WRONLY, 0)
-	readonly := os.IsPermission(err)
-	f.Close()
-
 	fileInfo, serr := os.Stat(filename)
-	if serr != nil && !os.IsNotExist(serr) {
+	if serr != nil && !errors.Is(serr, fs.ErrNotExist) {
 		return nil, serr
 	}
 	if serr == nil && fileInfo.IsDir() {
 		return nil, errors.New("Error: " + filename + " is a directory and cannot be opened")
 	}
+	if serr == nil && !fileInfo.Mode().IsRegular() {
+		return nil, errors.New("Error: " + filename + " is not a regular file and cannot be opened")
+	}
+
+	f, err := os.OpenFile(filename, os.O_WRONLY, 0)
+	readonly := errors.Is(err, fs.ErrPermission)
+	f.Close()
 
 	file, err := os.Open(filename)
 	if err == nil {
@@ -255,7 +260,7 @@ func NewBufferFromFileAtLoc(path string, btype BufType, cursorLoc Loc) (*Buffer,
 	}
 
 	var buf *Buffer
-	if os.IsNotExist(err) {
+	if errors.Is(err, fs.ErrNotExist) {
 		// File does not exist -- create an empty buffer with that name
 		buf = NewBufferFromString("", filename, btype)
 	} else if err != nil {
@@ -335,9 +340,9 @@ func NewBuffer(r io.Reader, size int64, path string, startcursor Loc, btype BufT
 		}
 		config.UpdatePathGlobLocals(b.Settings, absPath)
 
-		enc, err := htmlindex.Get(b.Settings["encoding"].(string))
+		b.encoding, err = htmlindex.Get(b.Settings["encoding"].(string))
 		if err != nil {
-			enc = unicode.UTF8
+			b.encoding = unicode.UTF8
 			b.Settings["encoding"] = "utf-8"
 		}
 
@@ -348,7 +353,7 @@ func NewBuffer(r io.Reader, size int64, path string, startcursor Loc, btype BufT
 			return NewBufferFromString("", "", btype)
 		}
 		if !hasBackup {
-			reader := bufio.NewReader(transform.NewReader(r, enc.NewDecoder()))
+			reader := bufio.NewReader(transform.NewReader(r, b.encoding.NewDecoder()))
 
 			var ff FileFormat = FFAuto
 
@@ -389,7 +394,7 @@ func NewBuffer(r io.Reader, size int64, path string, startcursor Loc, btype BufT
 	// we know the filetype now, so update per-filetype settings
 	config.UpdateFileTypeLocals(b.Settings, b.Settings["filetype"].(string))
 
-	if _, err := os.Stat(filepath.Join(config.ConfigDir, "buffers")); os.IsNotExist(err) {
+	if _, err := os.Stat(filepath.Join(config.ConfigDir, "buffers")); errors.Is(err, fs.ErrNotExist) {
 		os.Mkdir(filepath.Join(config.ConfigDir, "buffers"), os.ModePerm)
 	}
 
@@ -540,7 +545,7 @@ func (b *Buffer) ReOpen() error {
 	}
 
 	reader := bufio.NewReader(transform.NewReader(file, enc.NewDecoder()))
-	data, err := ioutil.ReadAll(reader)
+	data, err := io.ReadAll(reader)
 	txt := string(data)
 
 	if err != nil {

internal/buffer/save.go

@@ -5,18 +5,19 @@ import (
 	"bytes"
 	"errors"
 	"io"
+	"io/fs"
 	"os"
 	"os/exec"
 	"os/signal"
 	"path/filepath"
 	"runtime"
+	"sync/atomic"
+	"time"
 	"unicode"
 
 	"github.com/zyedidia/micro/v2/internal/config"
 	"github.com/zyedidia/micro/v2/internal/screen"
 	"github.com/zyedidia/micro/v2/internal/util"
-	"golang.org/x/text/encoding"
-	"golang.org/x/text/encoding/htmlindex"
 	"golang.org/x/text/transform"
 )
 
@@ -24,74 +25,178 @@ import (
 // because hashing is too slow
 const LargeFileThreshold = 50000
 
-// overwriteFile opens the given file for writing, truncating if one exists, and then calls
-// the supplied function with the file as io.Writer object, also making sure the file is
-// closed afterwards.
-func overwriteFile(name string, enc encoding.Encoding, fn func(io.Writer) error, withSudo bool) (err error) {
+type wrappedFile struct {
+	writeCloser io.WriteCloser
+	withSudo    bool
+	screenb     bool
+	cmd         *exec.Cmd
+	sigChan     chan os.Signal
+}
+
+type saveResponse struct {
+	size int
+	err  error
+}
+
+type saveRequest struct {
+	buf              *Buffer
+	path             string
+	withSudo         bool
+	newFile          bool
+	saveResponseChan chan saveResponse
+}
+
+var saveRequestChan chan saveRequest
+var backupRequestChan chan *Buffer
+
+func init() {
+	saveRequestChan = make(chan saveRequest, 10)
+	backupRequestChan = make(chan *Buffer, 10)
+
+	go func() {
+		duration := backupSeconds * float64(time.Second)
+		backupTicker := time.NewTicker(time.Duration(duration))
+
+		for {
+			select {
+			case sr := <-saveRequestChan:
+				size, err := sr.buf.safeWrite(sr.path, sr.withSudo, sr.newFile)
+				sr.saveResponseChan <- saveResponse{size, err}
+			case <-backupTicker.C:
+				for len(backupRequestChan) > 0 {
+					b := <-backupRequestChan
+					bfini := atomic.LoadInt32(&(b.fini)) != 0
+					if !bfini {
+						b.Backup()
+					}
+				}
+			}
+		}
+	}()
+}
+
+func openFile(name string, withSudo bool) (wrappedFile, error) {
+	var err error
 	var writeCloser io.WriteCloser
 	var screenb bool
 	var cmd *exec.Cmd
-	var c chan os.Signal
+	var sigChan chan os.Signal
 
 	if withSudo {
 		cmd = exec.Command(config.GlobalSettings["sucmd"].(string), "dd", "bs=4k", "of="+name)
-
-		if writeCloser, err = cmd.StdinPipe(); err != nil {
-			return
+		writeCloser, err = cmd.StdinPipe()
+		if err != nil {
+			return wrappedFile{}, err
 		}
 
-		c = make(chan os.Signal, 1)
+		sigChan = make(chan os.Signal, 1)
 		signal.Reset(os.Interrupt)
-		signal.Notify(c, os.Interrupt)
+		signal.Notify(sigChan, os.Interrupt)
 
 		screenb = screen.TempFini()
 		// need to start the process now, otherwise when we flush the file
 		// contents to its stdin it might hang because the kernel's pipe size
 		// is too small to handle the full file contents all at once
-		if err = cmd.Start(); err != nil {
+		err = cmd.Start()
+		if err != nil {
 			screen.TempStart(screenb)
 
 			signal.Notify(util.Sigterm, os.Interrupt)
-			signal.Stop(c)
+			signal.Stop(sigChan)
 
-			return
+			return wrappedFile{}, err
 		}
-	} else if writeCloser, err = os.OpenFile(name, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0666); err != nil {
-		return
-	}
-
-	w := bufio.NewWriter(transform.NewWriter(writeCloser, enc.NewEncoder()))
-	err = fn(w)
-
-	if err2 := w.Flush(); err2 != nil && err == nil {
-		err = err2
-	}
-	// Call Sync() on the file to make sure the content is safely on disk.
-	// Does not work with sudo as we don't have direct access to the file.
-	if !withSudo {
-		f := writeCloser.(*os.File)
-		if err2 := f.Sync(); err2 != nil && err == nil {
-			err = err2
+	} else {
+		writeCloser, err = os.OpenFile(name, os.O_WRONLY|os.O_CREATE, util.FileMode)
+		if err != nil {
+			return wrappedFile{}, err
 		}
 	}
-	if err2 := writeCloser.Close(); err2 != nil && err == nil {
-		err = err2
+
+	return wrappedFile{writeCloser, withSudo, screenb, cmd, sigChan}, nil
+}
+
+func (wf wrappedFile) Write(b *Buffer) (int, error) {
+	file := bufio.NewWriter(transform.NewWriter(wf.writeCloser, b.encoding.NewEncoder()))
+
+	b.Lock()
+	defer b.Unlock()
+
+	if len(b.lines) == 0 {
+		return 0, nil
 	}
 
-	if withSudo {
+	// end of line
+	var eol []byte
+	if b.Endings == FFDos {
+		eol = []byte{'\r', '\n'}
+	} else {
+		eol = []byte{'\n'}
+	}
+
+	if !wf.withSudo {
+		f := wf.writeCloser.(*os.File)
+		err := f.Truncate(0)
+		if err != nil {
+			return 0, err
+		}
+	}
+
+	// write lines
+	size, err := file.Write(b.lines[0].data)
+	if err != nil {
+		return 0, err
+	}
+
+	for _, l := range b.lines[1:] {
+		if _, err = file.Write(eol); err != nil {
+			return 0, err
+		}
+		if _, err = file.Write(l.data); err != nil {
+			return 0, err
+		}
+		size += len(eol) + len(l.data)
+	}
+
+	err = file.Flush()
+	if err == nil && !wf.withSudo {
+		// Call Sync() on the file to make sure the content is safely on disk.
+		f := wf.writeCloser.(*os.File)
+		err = f.Sync()
+	}
+	return size, err
+}
+
+func (wf wrappedFile) Close() error {
+	err := wf.writeCloser.Close()
+	if wf.withSudo {
 		// wait for dd to finish and restart the screen if we used sudo
-		err := cmd.Wait()
-		screen.TempStart(screenb)
+		err := wf.cmd.Wait()
+		screen.TempStart(wf.screenb)
 
 		signal.Notify(util.Sigterm, os.Interrupt)
-		signal.Stop(c)
+		signal.Stop(wf.sigChan)
 
 		if err != nil {
 			return err
 		}
 	}
+	return err
+}
 
-	return
+func (b *Buffer) overwriteFile(name string) (int, error) {
+	file, err := openFile(name, false)
+	if err != nil {
+		return 0, err
+	}
+
+	size, err := file.Write(b)
+
+	err2 := file.Close()
+	if err2 != nil && err == nil {
+		err = err2
+	}
+	return size, err
 }
 
 // Save saves the buffer to its default path
@@ -152,19 +257,35 @@ func (b *Buffer) saveToFile(filename string, withSudo bool, autoSave bool) error
 		}
 	}
 
-	// Update the last time this file was updated after saving
-	defer func() {
-		b.ModTime, _ = util.GetModTime(filename)
-		err = b.Serialize()
-	}()
+	filename, err = util.ReplaceHome(filename)
+	if err != nil {
+		return err
+	}
 
-	// Removes any tilde and replaces with the absolute path to home
-	absFilename, _ := util.ReplaceHome(filename)
+	newFile := false
+	fileInfo, err := os.Stat(filename)
+	if err != nil {
+		if !errors.Is(err, fs.ErrNotExist) {
+			return err
+		}
+		newFile = true
+	}
+	if err == nil && fileInfo.IsDir() {
+		return errors.New("Error: " + filename + " is a directory and cannot be saved")
+	}
+	if err == nil && !fileInfo.Mode().IsRegular() {
+		return errors.New("Error: " + filename + " is not a regular file and cannot be saved")
+	}
+
+	absFilename, err := filepath.Abs(filename)
+	if err != nil {
+		return err
+	}
 
 	// Get the leading path to the file | "." is returned if there's no leading path provided
 	if dirname := filepath.Dir(absFilename); dirname != "." {
 		// Check if the parent dirs don't exist
-		if _, statErr := os.Stat(dirname); os.IsNotExist(statErr) {
+		if _, statErr := os.Stat(dirname); errors.Is(statErr, fs.ErrNotExist) {
 			// Prompt to make sure they want to create the dirs that are missing
 			if b.Settings["mkparents"].(bool) {
 				// Create all leading dir(s) since they don't exist
@@ -178,49 +299,22 @@ func (b *Buffer) saveToFile(filename string, withSudo bool, autoSave bool) error
 		}
 	}
 
-	var fileSize int
-
-	enc, err := htmlindex.Get(b.Settings["encoding"].(string))
+	saveResponseChan := make(chan saveResponse)
+	saveRequestChan <- saveRequest{b, absFilename, withSudo, newFile, saveResponseChan}
+	result := <-saveResponseChan
+	err = result.err
 	if err != nil {
-		return err
-	}
+		if errors.Is(err, util.ErrOverwrite) {
+			screen.TermMessage(err)
+			err = errors.Unwrap(err)
 
-	fwriter := func(file io.Writer) (e error) {
-		if len(b.lines) == 0 {
-			return
+			b.UpdateModTime()
 		}
-
-		// end of line
-		var eol []byte
-		if b.Endings == FFDos {
-			eol = []byte{'\r', '\n'}
-		} else {
-			eol = []byte{'\n'}
-		}
-
-		// write lines
-		if fileSize, e = file.Write(b.lines[0].data); e != nil {
-			return
-		}
-
-		for _, l := range b.lines[1:] {
-			if _, e = file.Write(eol); e != nil {
-				return
-			}
-			if _, e = file.Write(l.data); e != nil {
-				return
-			}
-			fileSize += len(eol) + len(l.data)
-		}
-		return
-	}
-
-	if err = overwriteFile(absFilename, enc, fwriter, withSudo); err != nil {
 		return err
 	}
 
 	if !b.Settings["fastdirty"].(bool) {
-		if fileSize > LargeFileThreshold {
+		if result.size > LargeFileThreshold {
 			// For large files 'fastdirty' needs to be on
 			b.Settings["fastdirty"] = true
 		} else {
@@ -229,9 +323,64 @@ func (b *Buffer) saveToFile(filename string, withSudo bool, autoSave bool) error
 	}
 
 	b.Path = filename
-	absPath, _ := filepath.Abs(filename)
-	b.AbsPath = absPath
+	b.AbsPath = absFilename
 	b.isModified = false
+	b.UpdateModTime()
 	b.ReloadSettings(true)
+
+	err = b.Serialize()
 	return err
 }
+
+// safeWrite writes the buffer to a file in a "safe" way, preventing loss of the
+// contents of the file if it fails to write the new contents.
+// This means that the file is not overwritten directly but by writing to the
+// backup file first.
+func (b *Buffer) safeWrite(path string, withSudo bool, newFile bool) (int, error) {
+	file, err := openFile(path, withSudo)
+	if err != nil {
+		return 0, err
+	}
+
+	defer func() {
+		if newFile && err != nil {
+			os.Remove(path)
+		}
+	}()
+
+	backupDir := b.backupDir()
+	if _, err := os.Stat(backupDir); err != nil {
+		if !errors.Is(err, fs.ErrNotExist) {
+			return 0, err
+		}
+		if err = os.Mkdir(backupDir, os.ModePerm); err != nil {
+			return 0, err
+		}
+	}
+
+	backupName := util.DetermineEscapePath(backupDir, path)
+	_, err = b.overwriteFile(backupName)
+	if err != nil {
+		os.Remove(backupName)
+		return 0, err
+	}
+
+	b.forceKeepBackup = true
+	size, err := file.Write(b)
+	if err != nil {
+		err = util.OverwriteError{err, backupName}
+		return size, err
+	}
+	b.forceKeepBackup = false
+
+	if !b.keepBackup() {
+		os.Remove(backupName)
+	}
+
+	err2 := file.Close()
+	if err2 != nil && err == nil {
+		err = err2
+	}
+
+	return size, err
+}

internal/buffer/serialize.go

@@ -1,15 +1,13 @@
 package buffer
 
 import (
+	"bytes"
 	"encoding/gob"
 	"errors"
-	"io"
 	"os"
 	"path/filepath"
 	"time"
 
-	"golang.org/x/text/encoding"
-
 	"github.com/zyedidia/micro/v2/internal/config"
 	"github.com/zyedidia/micro/v2/internal/util"
 )
@@ -31,16 +29,18 @@ func (b *Buffer) Serialize() error {
 		return nil
 	}
 
-	name := filepath.Join(config.ConfigDir, "buffers", util.EscapePath(b.AbsPath))
-
-	return overwriteFile(name, encoding.Nop, func(file io.Writer) error {
-		err := gob.NewEncoder(file).Encode(SerializedBuffer{
-			b.EventHandler,
-			b.GetActiveCursor().Loc,
-			b.ModTime,
-		})
+	var buf bytes.Buffer
+	err := gob.NewEncoder(&buf).Encode(SerializedBuffer{
+		b.EventHandler,
+		b.GetActiveCursor().Loc,
+		b.ModTime,
+	})
+	if err != nil {
 		return err
-	}, false)
+	}
+
+	name := util.DetermineEscapePath(filepath.Join(config.ConfigDir, "buffers"), b.AbsPath)
+	return util.SafeWrite(name, buf.Bytes(), true)
 }
 
 // Unserialize loads the buffer info from config.ConfigDir/buffers
@@ -50,7 +50,7 @@ func (b *Buffer) Unserialize() error {
 	if b.Path == "" {
 		return nil
 	}
-	file, err := os.Open(filepath.Join(config.ConfigDir, "buffers", util.EscapePath(b.AbsPath)))
+	file, err := os.Open(util.DetermineEscapePath(filepath.Join(config.ConfigDir, "buffers"), b.AbsPath))
 	if err == nil {
 		defer file.Close()
 		var buffer SerializedBuffer

internal/buffer/settings.go

@@ -7,6 +7,8 @@ import (
 	"github.com/zyedidia/micro/v2/internal/config"
 	ulua "github.com/zyedidia/micro/v2/internal/lua"
 	"github.com/zyedidia/micro/v2/internal/screen"
+	"golang.org/x/text/encoding/htmlindex"
+	"golang.org/x/text/encoding/unicode"
 	luar "layeh.com/gopher-luar"
 )
 
@@ -97,6 +99,12 @@ func (b *Buffer) DoSetOptionNative(option string, nativeValue interface{}) {
 			b.UpdateRules()
 		}
 	} else if option == "encoding" {
+		enc, err := htmlindex.Get(b.Settings["encoding"].(string))
+		if err != nil {
+			enc = unicode.UTF8
+			b.Settings["encoding"] = "utf-8"
+		}
+		b.encoding = enc
 		b.isModified = true
 	} else if option == "readonly" && b.Type.Kind == BTDefault.Kind {
 		b.Type.Readonly = nativeValue.(bool)

internal/config/plugin_installer.go

@@ -5,7 +5,6 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -396,7 +395,7 @@ func (pv *PluginVersion) DownloadAndInstall(out io.Writer) error {
 		return err
 	}
 	defer resp.Body.Close()
-	data, err := ioutil.ReadAll(resp.Body)
+	data, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return err
 	}

internal/config/rtfiles.go

@@ -2,7 +2,6 @@ package config
 
 import (
 	"errors"
-	"io/ioutil"
 	"log"
 	"os"
 	"path"
@@ -81,7 +80,7 @@ func (rf realFile) Name() string {
 }
 
 func (rf realFile) Data() ([]byte, error) {
-	return ioutil.ReadFile(string(rf))
+	return os.ReadFile(string(rf))
 }
 
 func (af assetFile) Name() string {
@@ -107,7 +106,7 @@ func AddRealRuntimeFile(fileType RTFiletype, file RuntimeFile) {
 // AddRuntimeFilesFromDirectory registers each file from the given directory for
 // the filetype which matches the file-pattern
 func AddRuntimeFilesFromDirectory(fileType RTFiletype, directory, pattern string) {
-	files, _ := ioutil.ReadDir(directory)
+	files, _ := os.ReadDir(directory)
 	for _, f := range files {
 		if ok, _ := filepath.Match(pattern, f.Name()); !f.IsDir() && ok {
 			fullPath := filepath.Join(directory, f.Name())
@@ -194,14 +193,14 @@ func InitPlugins() {
 
 	// Search ConfigDir for plugin-scripts
 	plugdir := filepath.Join(ConfigDir, "plug")
-	files, _ := ioutil.ReadDir(plugdir)
+	files, _ := os.ReadDir(plugdir)
 
 	isID := regexp.MustCompile(`^[_A-Za-z0-9]+$`).MatchString
 
 	for _, d := range files {
 		plugpath := filepath.Join(plugdir, d.Name())
 		if stat, err := os.Stat(plugpath); err == nil && stat.IsDir() {
-			srcs, _ := ioutil.ReadDir(plugpath)
+			srcs, _ := os.ReadDir(plugpath)
 			p := new(Plugin)
 			p.Name = d.Name()
 			p.DirName = d.Name()
@@ -209,7 +208,7 @@ func InitPlugins() {
 				if strings.HasSuffix(f.Name(), ".lua") {
 					p.Srcs = append(p.Srcs, realFile(filepath.Join(plugdir, d.Name(), f.Name())))
 				} else if strings.HasSuffix(f.Name(), ".json") {
-					data, err := ioutil.ReadFile(filepath.Join(plugdir, d.Name(), f.Name()))
+					data, err := os.ReadFile(filepath.Join(plugdir, d.Name(), f.Name()))
 					if err != nil {
 						continue
 					}

internal/config/settings.go

@@ -4,7 +4,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -156,6 +155,10 @@ var (
 	VolatileSettings map[string]bool
 )
 
+func writeFile(name string, txt []byte) error {
+	return util.SafeWrite(name, txt, false)
+}
+
 func init() {
 	ModifiedSettings = make(map[string]bool)
 	VolatileSettings = make(map[string]bool)
@@ -222,7 +225,7 @@ func ReadSettings() error {
 	parsedSettings = make(map[string]interface{})
 	filename := filepath.Join(ConfigDir, "settings.json")
 	if _, e := os.Stat(filename); e == nil {
-		input, err := ioutil.ReadFile(filename)
+		input, err := os.ReadFile(filename)
 		if err != nil {
 			settingsParseError = true
 			return errors.New("Error reading settings.json file: " + err.Error())
@@ -356,7 +359,8 @@ func WriteSettings(filename string) error {
 		}
 
 		txt, _ := json.MarshalIndent(parsedSettings, "", "    ")
-		err = ioutil.WriteFile(filename, append(txt, '\n'), 0644)
+		txt = append(txt, '\n')
+		err = writeFile(filename, txt)
 	}
 	return err
 }
@@ -377,8 +381,9 @@ func OverwriteSettings(filename string) error {
 			}
 		}
 
-		txt, _ := json.MarshalIndent(settings, "", "    ")
-		err = ioutil.WriteFile(filename, append(txt, '\n'), 0644)
+		txt, _ := json.MarshalIndent(parsedSettings, "", "    ")
+		txt = append(txt, '\n')
+		err = writeFile(filename, txt)
 	}
 	return err
 }

internal/info/history.go

@@ -1,12 +1,16 @@
 package info
 
 import (
+	"bytes"
 	"encoding/gob"
+	"errors"
+	"io/fs"
 	"os"
 	"path/filepath"
 	"strings"
 
 	"github.com/zyedidia/micro/v2/internal/config"
+	"github.com/zyedidia/micro/v2/internal/screen"
 	"github.com/zyedidia/micro/v2/internal/util"
 )
 
@@ -17,24 +21,23 @@ func (i *InfoBuf) LoadHistory() {
 	if config.GetGlobalOption("savehistory").(bool) {
 		file, err := os.Open(filepath.Join(config.ConfigDir, "buffers", "history"))
 		var decodedMap map[string][]string
-		if err == nil {
-			defer file.Close()
-			decoder := gob.NewDecoder(file)
-			err = decoder.Decode(&decodedMap)
-
-			if err != nil {
-				i.Error("Error loading history:", err)
-				return
+		if err != nil {
+			if !errors.Is(err, fs.ErrNotExist) {
+				i.Error("Error loading history: ", err)
 			}
+			return
+		}
+
+		defer file.Close()
+		err = gob.NewDecoder(file).Decode(&decodedMap)
+		if err != nil {
+			i.Error("Error decoding history: ", err)
+			return
 		}
 
 		if decodedMap != nil {
 			i.History = decodedMap
-		} else {
-			i.History = make(map[string][]string)
 		}
-	} else {
-		i.History = make(map[string][]string)
 	}
 }
 
@@ -49,16 +52,18 @@ func (i *InfoBuf) SaveHistory() {
 			}
 		}
 
-		file, err := os.Create(filepath.Join(config.ConfigDir, "buffers", "history"))
-		if err == nil {
-			defer file.Close()
-			encoder := gob.NewEncoder(file)
+		var buf bytes.Buffer
+		err := gob.NewEncoder(&buf).Encode(i.History)
+		if err != nil {
+			screen.TermMessage("Error encoding history: ", err)
+			return
+		}
 
-			err = encoder.Encode(i.History)
-			if err != nil {
-				i.Error("Error saving history:", err)
-				return
-			}
+		filename := filepath.Join(config.ConfigDir, "buffers", "history")
+		err = util.SafeWrite(filename, buf.Bytes(), true)
+		if err != nil {
+			screen.TermMessage("Error saving history: ", err)
+			return
 		}
 	}
 }

internal/util/util.go

@@ -6,7 +6,9 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"net/http"
+	"net/url"
 	"os"
 	"os/user"
 	"path/filepath"
@@ -43,8 +45,44 @@ var (
 	Stdout *bytes.Buffer
 	// Sigterm is a channel where micro exits when written
 	Sigterm chan os.Signal
+
+	// To be used for fails on (over-)write with safe writes
+	ErrOverwrite = OverwriteError{}
 )
 
+// To be used for file writes before umask is applied
+const FileMode os.FileMode = 0666
+
+const OverwriteFailMsg = `An error occurred while writing to the file:
+
+%s
+
+The file may be corrupted now. The good news is that it has been
+successfully backed up. Next time you open this file with Micro,
+Micro will ask if you want to recover it from the backup.
+
+The backup path is:
+
+%s`
+
+// OverwriteError is a custom error to add additional information
+type OverwriteError struct {
+	What       error
+	BackupName string
+}
+
+func (e OverwriteError) Error() string {
+	return fmt.Sprintf(OverwriteFailMsg, e.What, e.BackupName)
+}
+
+func (e OverwriteError) Is(target error) bool {
+	return target == ErrOverwrite
+}
+
+func (e OverwriteError) Unwrap() error {
+	return e.What
+}
+
 func init() {
 	var err error
 	SemVersion, err = semver.Make(Version)
@@ -408,8 +446,17 @@ func GetModTime(path string) (time.Time, error) {
 	return info.ModTime(), nil
 }
 
-// EscapePath replaces every path separator in a given path with a %
-func EscapePath(path string) string {
+func AppendBackupSuffix(path string) string {
+	return path + ".micro-backup"
+}
+
+// EscapePathUrl encodes the path in URL query form
+func EscapePathUrl(path string) string {
+	return url.QueryEscape(filepath.ToSlash(path))
+}
+
+// EscapePathLegacy replaces every path separator in a given path with a %
+func EscapePathLegacy(path string) string {
 	path = filepath.ToSlash(path)
 	if runtime.GOOS == "windows" {
 		// ':' is not valid in a path name on Windows but is ok on Unix
@@ -418,6 +465,24 @@ func EscapePath(path string) string {
 	return strings.ReplaceAll(path, "/", "%")
 }
 
+// DetermineEscapePath escapes a path, determining whether it should be escaped
+// using URL encoding (preferred, since it encodes unambiguously) or
+// legacy encoding with '%' (for backward compatibility, if the legacy-escaped
+// path exists in the given directory).
+func DetermineEscapePath(dir string, path string) string {
+	url := filepath.Join(dir, EscapePathUrl(path))
+	if _, err := os.Stat(url); err == nil {
+		return url
+	}
+
+	legacy := filepath.Join(dir, EscapePathLegacy(path))
+	if _, err := os.Stat(legacy); err == nil {
+		return legacy
+	}
+
+	return url
+}
+
 // GetLeadingWhitespace returns the leading whitespace of the given byte array
 func GetLeadingWhitespace(b []byte) []byte {
 	ws := []byte{}
@@ -590,3 +655,77 @@ func HttpRequest(method string, url string, headers []string) (resp *http.Respon
 	}
 	return client.Do(req)
 }
+
+// SafeWrite writes bytes to a file in a "safe" way, preventing loss of the
+// contents of the file if it fails to write the new contents.
+// This means that the file is not overwritten directly but by writing to a
+// temporary file first.
+//
+// If rename is true, write is performed atomically, by renaming the temporary
+// file to the target file after the data is successfully written to the
+// temporary file. This guarantees that the file will not remain in a corrupted
+// state, but it also has limitations, e.g. the file should not be a symlink
+// (otherwise SafeWrite silently replaces this symlink with a regular file),
+// the file creation date in Linux is not preserved (since the file inode
+// changes) etc. Use SafeWrite with rename=true for files that are only created
+// and used by micro for its own needs and are not supposed to be used directly
+// by the user.
+//
+// If rename is false, write is performed by overwriting the target file after
+// the data is successfully written to the temporary file.
+// This means that the target file may remain corrupted if overwrite fails,
+// but in such case the temporary file is preserved as a backup so the file
+// can be recovered later. So it is less convenient than atomic write but more
+// universal. Use SafeWrite with rename=false for files that may be managed
+// directly by the user, like settings.json and bindings.json.
+func SafeWrite(path string, bytes []byte, rename bool) error {
+	var err error
+	if _, err = os.Stat(path); err != nil {
+		if !errors.Is(err, fs.ErrNotExist) {
+			return err
+		}
+		// Force rename for new files!
+		rename = true
+	}
+
+	var file *os.File
+	if !rename {
+		file, err = os.OpenFile(path, os.O_WRONLY|os.O_CREATE, FileMode)
+		if err != nil {
+			return err
+		}
+		defer file.Close()
+	}
+
+	tmp := AppendBackupSuffix(path)
+	err = os.WriteFile(tmp, bytes, FileMode)
+	if err != nil {
+		os.Remove(tmp)
+		return err
+	}
+
+	if rename {
+		err = os.Rename(tmp, path)
+	} else {
+		err = file.Truncate(0)
+		if err == nil {
+			_, err = file.Write(bytes)
+		}
+		if err == nil {
+			err = file.Sync()
+		}
+	}
+	if err != nil {
+		if rename {
+			os.Remove(tmp)
+		} else {
+			err = OverwriteError{err, tmp}
+		}
+		return err
+	}
+
+	if !rename {
+		os.Remove(tmp)
+	}
+	return nil
+}

runtime/syntax/make_headers.go

@@ -6,7 +6,6 @@ package main
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"strings"
 	"time"
@@ -34,7 +33,7 @@ func main() {
 	if len(os.Args) > 1 {
 		os.Chdir(os.Args[1])
 	}
-	files, _ := ioutil.ReadDir(".")
+	files, _ := os.ReadDir(".")
 	for _, f := range files {
 		fname := f.Name()
 		if strings.HasSuffix(fname, ".yaml") {
@@ -46,7 +45,7 @@ func main() {
 func convert(name string) {
 	filename := name + ".yaml"
 	var hdr HeaderYaml
-	source, err := ioutil.ReadFile(filename)
+	source, err := os.ReadFile(filename)
 	if err != nil {
 		panic(err)
 	}
@@ -68,7 +67,7 @@ func encode(name string, c HeaderYaml) {
 
 func decode(name string) Header {
 	start := time.Now()
-	data, _ := ioutil.ReadFile(name + ".hdr")
+	data, _ := os.ReadFile(name + ".hdr")
 	strs := bytes.Split(data, []byte{'\n'})
 	var hdr Header
 	hdr.FileType = string(strs[0])

runtime/syntax/syntax_converter.go

@@ -4,7 +4,6 @@ package main
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"regexp"
 	"strings"
@@ -161,6 +160,6 @@ func main() {
 		return
 	}
 
-	data, _ := ioutil.ReadFile(os.Args[1])
+	data, _ := os.ReadFile(os.Args[1])
 	fmt.Print(generateFile(parseFile(string(data), os.Args[1])))
 }

tools/info-plist.go

@@ -37,7 +37,7 @@ func main() {
 	</plist>
 	`
 
-	err := os.WriteFile("/tmp/micro-info.plist", []byte(rawInfoPlist), 0644)
+	err := os.WriteFile("/tmp/micro-info.plist", []byte(rawInfoPlist), 0666)
 	if err != nil {
 		panic(err)
 	}

tools/remove-nightly-assets.go

@@ -4,7 +4,7 @@ package main
 
 import (
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"os/exec"
 	"strings"
@@ -19,7 +19,7 @@ func main() {
 		return
 	}
 	defer resp.Body.Close()
-	body, err := ioutil.ReadAll(resp.Body)
+	body, err := io.ReadAll(resp.Body)
 
 	var data interface{}
 

tools/testgen.go

@@ -4,7 +4,6 @@ package main
 
 import (
 	"fmt"
-	"io/ioutil"
 	"log"
 	"os"
 	"regexp"
@@ -210,7 +209,7 @@ func main() {
 	var tests []test
 
 	for _, filename := range os.Args[1:] {
-		source, err := ioutil.ReadFile(filename)
+		source, err := os.ReadFile(filename)
 		if err != nil {
 			log.Fatalln(err)
 		}