etcdserver,pkg: remove temp files in snap dir when etcdserver starting

- Backporting: etcd-io#12846
- Reference: etcd-io#14232

etcdserver/server.go

@@ -25,6 +25,7 @@ import (
 	"os"
 	"path"
 	"regexp"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -323,6 +324,17 @@ func NewServer(cfg ServerConfig) (srv *EtcdServer, err error) {
 			plog.Fatalf("create snapshot directory error: %v", err)
 		}
 	}
+
+	if err = fileutil.RemoveMatchFile(cfg.Logger, cfg.SnapDir(), func(fileName string) bool {
+		return strings.HasPrefix(fileName, "tmp")
+	}); err != nil {
+		cfg.Logger.Error(
+			"failed to remove temp file(s) in snapshot directory",
+			zap.String("path", cfg.SnapDir()),
+			zap.Error(err),
+		)
+	}
+
 	ss := snap.New(cfg.Logger, cfg.SnapDir())
 
 	bepath := cfg.backendPath()

pkg/fileutil/fileutil.go

@@ -127,3 +127,35 @@ func CheckDirPermission(dir string, perm os.FileMode) error {
 	}
 	return nil
 }
+
+// RemoveMatchFile deletes file if matchFunc is true on an existing dir
+// Returns error if the dir does not exist or remove file fail
+func RemoveMatchFile(lg *zap.Logger, dir string, matchFunc func(fileName string) bool) error {
+	if lg == nil {
+		lg = zap.NewNop()
+	}
+	if !Exist(dir) {
+		return fmt.Errorf("directory %s does not exist", dir)
+	}
+	fileNames, err := ReadDir(dir)
+	if err != nil {
+		return err
+	}
+	var removeFailedFiles []string
+	for _, fileName := range fileNames {
+		if matchFunc(fileName) {
+			file := filepath.Join(dir, fileName)
+			if err = os.Remove(file); err != nil {
+				removeFailedFiles = append(removeFailedFiles, fileName)
+				lg.Error("remove file failed",
+					zap.String("file", file),
+					zap.Error(err))
+				continue
+			}
+		}
+	}
+	if len(removeFailedFiles) != 0 {
+		return fmt.Errorf("remove file(s) %v error", removeFailedFiles)
+	}
+	return nil
+}

pkg/fileutil/fileutil_test.go

@@ -166,3 +166,45 @@ func TestDirPermission(t *testing.T) {
 		t.Errorf("expected error, got nil")
 	}
 }
+
+func TestRemoveMatchFile(t *testing.T) {
+	tmpdir := t.TempDir()
+	defer os.RemoveAll(tmpdir)
+	f, err := ioutil.TempFile(tmpdir, "tmp")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+	f, err = ioutil.TempFile(tmpdir, "foo.tmp")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+
+	err = RemoveMatchFile(zaptest.NewLogger(t), tmpdir, func(fileName string) bool {
+		return strings.HasPrefix(fileName, "tmp")
+	})
+	if err != nil {
+		t.Errorf("expected nil, got error")
+	}
+	fnames, err := ReadDir(tmpdir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(fnames) != 1 {
+		t.Errorf("expected exist 1 files, got %d", len(fnames))
+	}
+
+	f, err = ioutil.TempFile(tmpdir, "tmp")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+	err = RemoveMatchFile(zaptest.NewLogger(t), tmpdir, func(fileName string) bool {
+		os.Remove(filepath.Join(tmpdir, fileName))
+		return strings.HasPrefix(fileName, "tmp")
+	})
+	if err == nil {
+		t.Errorf("expected error, got nil")
+	}
+}