GODT-1743: Terminate running bridge if has old version.

internal/app/base/singleinstance_unix.go

@@ -0,0 +1,101 @@
+// Copyright (c) 2022 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
+
+//go:build !windows
+// +build !windows
+
+package base
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/Masterminds/semver/v3"
+	"github.com/ProtonMail/proton-bridge/v2/internal/config/settings"
+	"github.com/ProtonMail/proton-bridge/v2/internal/constants"
+	"github.com/allan-simon/go-singleinstance"
+	"golang.org/x/sys/unix"
+)
+
+// checkSingleInstance returns error if a bridge instance is already running
+// This instance should be stop and window of running window should be brought
+// to focus.
+//
+// For macOS and Linux when already running version is older than this instance
+// it will kill old and continue with this new bridge (i.e. no error returned).
+func checkSingleInstance(lockFilePath string, settingsObj *settings.Settings) (*os.File, error) {
+	if lock, err := singleinstance.CreateLockFile(lockFilePath); err == nil {
+		// Bridge is not runnig, continue normally
+		return lock, nil
+	}
+
+	if err := runningVersionIsOlder(settingsObj); err != nil {
+		return nil, err
+	}
+
+	pid, err := getPID(lockFilePath)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := unix.Kill(pid, unix.SIGTERM); err != nil {
+		return nil, err
+	}
+
+	// Need to wait some time to release file lock
+	time.Sleep(time.Second)
+
+	return singleinstance.CreateLockFile(lockFilePath)
+}
+
+func getPID(lockFilePath string) (int, error) {
+	file, err := os.Open(filepath.Clean(lockFilePath))
+	if err != nil {
+		return 0, err
+	}
+	defer func() { _ = file.Close() }()
+
+	rawPID := make([]byte, 10) // PID is probably up to 7 digits long, 10 should be enough
+	n, err := file.Read(rawPID)
+	if err != nil {
+		return 0, err
+	}
+
+	return strconv.Atoi(strings.TrimSpace(string(rawPID[:n])))
+}
+
+func runningVersionIsOlder(settingsObj *settings.Settings) error {
+	currentVer, err := semver.StrictNewVersion(constants.Version)
+	if err != nil {
+		return err
+	}
+
+	runningVer, err := semver.StrictNewVersion(settingsObj.Get(settings.LastVersionKey))
+	if err != nil {
+		return err
+	}
+
+	if !runningVer.LessThan(currentVer) {
+		return errors.New("running version is not older")
+	}
+
+	return nil
+}