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

internal/app/migration.go

@@ -0,0 +1,106 @@
+// 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 (
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/allan-simon/go-singleinstance"
+	"github.com/hashicorp/go-multierror"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+func migrateOldVersions() (allErrors error) {
+	cacheDir, cacheError := os.UserCacheDir()
+	if cacheError != nil {
+		allErrors = multierror.Append(allErrors, errors.Wrap(cacheError, "cannot get os cache"))
+		return // not need to continue for now (with more migrations might be still ok to continue)
+	}
+
+	if err := killV2AppAndRemoveV2LockFiles(filepath.Join(cacheDir, "protonmail", "bridge", "bridge.lock")); err != nil {
+		allErrors = multierror.Append(allErrors, errors.Wrap(err, "cannot migrate lockfiles"))
+	}
+
+	return
+}
+
+func killV2AppAndRemoveV2LockFiles(lockFilePathV2 string) error {
+	l := logrus.WithField("path", lockFilePathV2)
+
+	if _, err := os.Stat(lockFilePathV2); os.IsNotExist(err) {
+		l.Debug("no v2 lockfile")
+		return nil
+	}
+
+	lock, err := singleinstance.CreateLockFile(lockFilePathV2)
+
+	if err == nil {
+		l.Debug("no other v2 instance is running")
+
+		if errClose := lock.Close(); errClose != nil {
+			l.WithError(errClose).Error("Cannot close lock file")
+		}
+
+		return os.Remove(lockFilePathV2)
+	}
+
+	// The other instance is an older version, so we should kill it.
+	pid, err := getPID(lockFilePathV2)
+	if err != nil {
+		return errors.Wrap(err, "cannot get v2 pid")
+	}
+
+	if err := killPID(pid); err != nil {
+		return errors.Wrapf(err, "cannot kill v2 app (PID %d)", pid)
+	}
+
+	// Need to wait some time to release file lock
+	time.Sleep(time.Second)
+
+	return nil
+}
+
+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 killPID(pid int) error {
+	p, err := os.FindProcess(pid)
+	if err != nil {
+		return err
+	}
+
+	return p.Kill()
+}