style: gofumpt all the things (#9829)

Literally `gofumpt -w .` from the top level dir. Guaranteed to be minor
style changes only and nothing else.

@imsodin per request?

lib/osutil/atomic.go

@@ -101,7 +101,7 @@ func (w *AtomicWriter) Close() error {
 		// On Windows, we might not be allowed to rename over the file
 		// because it's read-only. Get us some write permissions and try
 		// again.
-		_ = w.fs.Chmod(w.path, 0644)
+		_ = w.fs.Chmod(w.path, 0o644)
 		err = w.fs.Rename(w.next.Name(), w.path)
 	}
 	if err != nil {

lib/osutil/atomic_test.go

@@ -17,7 +17,7 @@ func TestCreateAtomicCreate(t *testing.T) {
 	os.RemoveAll("testdata")
 	defer os.RemoveAll("testdata")
 
-	if err := os.Mkdir("testdata", 0755); err != nil {
+	if err := os.Mkdir("testdata", 0o755); err != nil {
 		t.Fatal(err)
 	}
 
@@ -52,10 +52,11 @@ func TestCreateAtomicCreate(t *testing.T) {
 }
 
 func TestCreateAtomicReplace(t *testing.T) {
-	testCreateAtomicReplace(t, 0666)
+	testCreateAtomicReplace(t, 0o666)
 }
+
 func TestCreateAtomicReplaceReadOnly(t *testing.T) {
-	testCreateAtomicReplace(t, 0444) // windows compatible read-only bits
+	testCreateAtomicReplace(t, 0o444) // windows compatible read-only bits
 }
 
 func testCreateAtomicReplace(t *testing.T, oldPerms os.FileMode) {
@@ -66,7 +67,7 @@ func testCreateAtomicReplace(t *testing.T, oldPerms os.FileMode) {
 
 	os.RemoveAll(testdir)
 
-	if err := os.Mkdir(testdir, 0755); err != nil {
+	if err := os.Mkdir(testdir, 0o755); err != nil {
 		t.Fatal(err)
 	}
 

lib/osutil/atomic_unix_test.go

@@ -38,7 +38,7 @@ func TestTempFilePermissions(t *testing.T) {
 	// The temp file should have 0600 permissions at the most, or we have a
 	// security problem in CreateAtomic.
 	t.Logf("Got 0%03o", info.Mode())
-	if info.Mode()&^0600 != 0 {
+	if info.Mode()&^0o600 != 0 {
 		t.Errorf("Permission 0%03o is too generous", info.Mode())
 	}
 }

lib/osutil/osutil.go

@@ -84,14 +84,14 @@ func Copy(method fs.CopyRangeMethod, src, dst fs.Filesystem, from, to string) (e
 func withPreparedTarget(filesystem fs.Filesystem, from, to string, f func() error) error {
 	// Make sure the destination directory is writeable
 	toDir := filepath.Dir(to)
-	if info, err := filesystem.Stat(toDir); err == nil && info.IsDir() && info.Mode()&0200 == 0 {
-		filesystem.Chmod(toDir, 0755)
+	if info, err := filesystem.Stat(toDir); err == nil && info.IsDir() && info.Mode()&0o200 == 0 {
+		filesystem.Chmod(toDir, 0o755)
 		defer filesystem.Chmod(toDir, info.Mode())
 	}
 
 	// On Windows, make sure the destination file is writeable (or we can't delete it)
 	if build.IsWindows {
-		filesystem.Chmod(to, 0666)
+		filesystem.Chmod(to, 0o666)
 		if !strings.EqualFold(from, to) {
 			err := filesystem.Remove(to)
 			if err != nil && !fs.IsNotExist(err) {

lib/osutil/tempfile.go

@@ -16,8 +16,10 @@ import (
 	"github.com/syncthing/syncthing/lib/fs"
 )
 
-var rand uint32
-var randmu sync.Mutex
+var (
+	rand   uint32
+	randmu sync.Mutex
+)
 
 func reseed() uint32 {
 	return uint32(time.Now().UnixNano() + int64(os.Getpid()))
@@ -48,7 +50,7 @@ func TempFile(filesystem fs.Filesystem, dir, prefix string) (f fs.File, err erro
 	nconflict := 0
 	for i := 0; i < 10000; i++ {
 		name := filepath.Join(dir, prefix+nextSuffix())
-		f, err = filesystem.OpenFile(name, fs.OptReadWrite|fs.OptCreate|fs.OptExclusive, 0600)
+		f, err = filesystem.OpenFile(name, fs.OptReadWrite|fs.OptCreate|fs.OptExclusive, 0o600)
 		if fs.IsExist(err) {
 			if nconflict++; nconflict > 10 {
 				randmu.Lock()