Import/Export backend

internal/cmd/restart.go

@@ -0,0 +1,108 @@
+// Copyright (c) 2020 Proton Technologies AG
+//
+// This file is part of ProtonMail Bridge.
+//
+// ProtonMail 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.
+//
+// ProtonMail 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 ProtonMail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+
+	"github.com/ProtonMail/proton-bridge/internal/frontend"
+	"github.com/ProtonMail/proton-bridge/pkg/config"
+	"github.com/urfave/cli"
+)
+
+const (
+	// After how many crashes app gives up starting.
+	maxAllowedCrashes = 10
+)
+
+var (
+	// How many crashes happened so far in a row.
+	// It will be filled from args by `filterRestartNumberFromArgs`.
+	// Every call of `HandlePanic` will increase this number.
+	// Then it will be passed as argument to the next try by `RestartApp`.
+	numberOfCrashes = 0 //nolint[gochecknoglobals]
+)
+
+// filterRestartNumberFromArgs removes flag with a number how many restart we already did.
+// See restartApp how that number is used.
+func filterRestartNumberFromArgs() {
+	tmp := os.Args[:0]
+	for i, arg := range os.Args {
+		if !strings.HasPrefix(arg, "--restart_") {
+			tmp = append(tmp, arg)
+			continue
+		}
+		var err error
+		numberOfCrashes, err = strconv.Atoi(os.Args[i][10:])
+		if err != nil {
+			numberOfCrashes = maxAllowedCrashes
+		}
+	}
+	os.Args = tmp
+}
+
+// DisableRestart disables restart once `RestartApp` is called.
+func DisableRestart() {
+	numberOfCrashes = maxAllowedCrashes
+}
+
+// RestartApp starts a new instance in background.
+func RestartApp() {
+	if numberOfCrashes >= maxAllowedCrashes {
+		log.Error("Too many crashes")
+		return
+	}
+	if exeFile, err := os.Executable(); err == nil {
+		arguments := append(os.Args[1:], fmt.Sprintf("--restart_%d", numberOfCrashes))
+		cmd := exec.Command(exeFile, arguments...) //nolint[gosec]
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		cmd.Stdin = os.Stdin
+		if err := cmd.Start(); err != nil {
+			log.Error("Restart failed: ", err)
+		}
+	}
+}
+
+// PanicHandler defines HandlePanic which can be used anywhere in defer.
+type PanicHandler struct {
+	AppName string
+	Config  *config.Config
+	Err     *error // Pointer to error of cli action.
+}
+
+// HandlePanic should be called in defer to ensure restart of app after error.
+func (ph *PanicHandler) HandlePanic() {
+	r := recover()
+	if r == nil {
+		return
+	}
+
+	config.HandlePanic(ph.Config, fmt.Sprintf("Recover: %v", r))
+	frontend.HandlePanic(ph.AppName)
+
+	*ph.Err = cli.NewExitError("Panic and restart", 255)
+	numberOfCrashes++
+	log.Error("Restarting after panic")
+	RestartApp()
+	os.Exit(255)
+}