GODT-2056: kill old bridge from v2 lock file.

internal/app/singleinstance.go

@@ -0,0 +1,70 @@
+// 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/>.
+
+package app
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/Masterminds/semver/v3"
+	"github.com/ProtonMail/proton-bridge/v2/internal/focus"
+	"github.com/allan-simon/go-singleinstance"
+	"github.com/sirupsen/logrus"
+)
+
+// checkSingleInstance checks if another instance of the application is already running.
+// It tries to create a lock file at the given path.
+// If it succeeds, it returns the lock file and a nil error.
+//
+// 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, curVersion *semver.Version) (*os.File, error) {
+	if lock, err := singleinstance.CreateLockFile(lockFilePath); err == nil {
+		logrus.WithField("path", lockFilePath).Debug("Created lock file; no other instance is running")
+		return lock, nil
+	}
+
+	logrus.Debug("Failed to create lock file; another instance is running")
+
+	// We couldn't create the lock file, so another instance is probably running.
+	// Check if it's an older version of the app.
+	lastVersion, ok := focus.TryVersion()
+	if !ok {
+		return nil, fmt.Errorf("failed to determine version of running instance")
+	}
+
+	if !lastVersion.LessThan(curVersion) {
+		return nil, fmt.Errorf("running instance is newer than this one")
+	}
+
+	// The other instance is an older version, so we should kill it.
+	pid, err := getPID(lockFilePath)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := killPID(pid); err != nil {
+		return nil, err
+	}
+
+	// Need to wait some time to release file lock
+	time.Sleep(time.Second)
+
+	return singleinstance.CreateLockFile(lockFilePath)
+}