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service_windows.go
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service_windows.go
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// Copyright (c) 2013-2016 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package main
import (
"fmt"
"os"
"path/filepath"
"time"
"github.com/btcsuite/winsvc/eventlog"
"github.com/btcsuite/winsvc/mgr"
"github.com/btcsuite/winsvc/svc"
)
const (
// svcName is the name of btcd service.
svcName = "btcdsvc"
// svcDisplayName is the service name that will be shown in the windows
// services list. Not the svcName is the "real" name which is used
// to control the service. This is only for display purposes.
svcDisplayName = "Btcd Service"
// svcDesc is the description of the service.
svcDesc = "Downloads and stays synchronized with the bitcoin block " +
"chain and provides chain services to applications."
)
// elog is used to send messages to the Windows event log.
var elog *eventlog.Log
// logServiceStartOfDay logs information about btcd when the main server has
// been started to the Windows event log.
func logServiceStartOfDay(srvr *server) {
var message string
message += fmt.Sprintf("Version %s\n", version())
message += fmt.Sprintf("Configuration directory: %s\n", defaultHomeDir)
message += fmt.Sprintf("Configuration file: %s\n", cfg.ConfigFile)
message += fmt.Sprintf("Data directory: %s\n", cfg.DataDir)
elog.Info(1, message)
}
// btcdService houses the main service handler which handles all service
// updates and launching btcdMain.
type btcdService struct{}
// Execute is the main entry point the winsvc package calls when receiving
// information from the Windows service control manager. It launches the
// long-running btcdMain (which is the real meat of btcd), handles service
// change requests, and notifies the service control manager of changes.
func (s *btcdService) Execute(args []string, r <-chan svc.ChangeRequest, changes chan<- svc.Status) (bool, uint32) {
// Service start is pending.
const cmdsAccepted = svc.AcceptStop | svc.AcceptShutdown
changes <- svc.Status{State: svc.StartPending}
// Start btcdMain in a separate goroutine so the service can start
// quickly. Shutdown (along with a potential error) is reported via
// doneChan. serverChan is notified with the main server instance once
// it is started so it can be gracefully stopped.
doneChan := make(chan error)
serverChan := make(chan *server)
go func() {
err := btcdMain(serverChan)
doneChan <- err
}()
// Service is now started.
changes <- svc.Status{State: svc.Running, Accepts: cmdsAccepted}
var mainServer *server
loop:
for {
select {
case c := <-r:
switch c.Cmd {
case svc.Interrogate:
changes <- c.CurrentStatus
case svc.Stop, svc.Shutdown:
// Service stop is pending. Don't accept any
// more commands while pending.
changes <- svc.Status{State: svc.StopPending}
// Signal the main function to exit.
shutdownRequestChannel <- struct{}{}
default:
elog.Error(1, fmt.Sprintf("Unexpected control "+
"request #%d.", c))
}
case srvr := <-serverChan:
mainServer = srvr
logServiceStartOfDay(mainServer)
case err := <-doneChan:
if err != nil {
elog.Error(1, err.Error())
}
break loop
}
}
// Service is now stopped.
changes <- svc.Status{State: svc.Stopped}
return false, 0
}
// installService attempts to install the btcd service. Typically this should
// be done by the msi installer, but it is provided here since it can be useful
// for development.
func installService() error {
// Get the path of the current executable. This is needed because
// os.Args[0] can vary depending on how the application was launched.
// For example, under cmd.exe it will only be the name of the app
// without the path or extension, but under mingw it will be the full
// path including the extension.
exePath, err := filepath.Abs(os.Args[0])
if err != nil {
return err
}
if filepath.Ext(exePath) == "" {
exePath += ".exe"
}
// Connect to the windows service manager.
serviceManager, err := mgr.Connect()
if err != nil {
return err
}
defer serviceManager.Disconnect()
// Ensure the service doesn't already exist.
service, err := serviceManager.OpenService(svcName)
if err == nil {
service.Close()
return fmt.Errorf("service %s already exists", svcName)
}
// Install the service.
service, err = serviceManager.CreateService(svcName, exePath, mgr.Config{
DisplayName: svcDisplayName,
Description: svcDesc,
})
if err != nil {
return err
}
defer service.Close()
// Support events to the event log using the standard "standard" Windows
// EventCreate.exe message file. This allows easy logging of custom
// messges instead of needing to create our own message catalog.
eventlog.Remove(svcName)
eventsSupported := uint32(eventlog.Error | eventlog.Warning | eventlog.Info)
return eventlog.InstallAsEventCreate(svcName, eventsSupported)
}
// removeService attempts to uninstall the btcd service. Typically this should
// be done by the msi uninstaller, but it is provided here since it can be
// useful for development. Not the eventlog entry is intentionally not removed
// since it would invalidate any existing event log messages.
func removeService() error {
// Connect to the windows service manager.
serviceManager, err := mgr.Connect()
if err != nil {
return err
}
defer serviceManager.Disconnect()
// Ensure the service exists.
service, err := serviceManager.OpenService(svcName)
if err != nil {
return fmt.Errorf("service %s is not installed", svcName)
}
defer service.Close()
// Remove the service.
return service.Delete()
}
// startService attempts to start the btcd service.
func startService() error {
// Connect to the windows service manager.
serviceManager, err := mgr.Connect()
if err != nil {
return err
}
defer serviceManager.Disconnect()
service, err := serviceManager.OpenService(svcName)
if err != nil {
return fmt.Errorf("could not access service: %v", err)
}
defer service.Close()
err = service.Start(os.Args)
if err != nil {
return fmt.Errorf("could not start service: %v", err)
}
return nil
}
// controlService allows commands which change the status of the service. It
// also waits for up to 10 seconds for the service to change to the passed
// state.
func controlService(c svc.Cmd, to svc.State) error {
// Connect to the windows service manager.
serviceManager, err := mgr.Connect()
if err != nil {
return err
}
defer serviceManager.Disconnect()
service, err := serviceManager.OpenService(svcName)
if err != nil {
return fmt.Errorf("could not access service: %v", err)
}
defer service.Close()
status, err := service.Control(c)
if err != nil {
return fmt.Errorf("could not send control=%d: %v", c, err)
}
// Send the control message.
timeout := time.Now().Add(10 * time.Second)
for status.State != to {
if timeout.Before(time.Now()) {
return fmt.Errorf("timeout waiting for service to go "+
"to state=%d", to)
}
time.Sleep(300 * time.Millisecond)
status, err = service.Query()
if err != nil {
return fmt.Errorf("could not retrieve service "+
"status: %v", err)
}
}
return nil
}
// performServiceCommand attempts to run one of the supported service commands
// provided on the command line via the service command flag. An appropriate
// error is returned if an invalid command is specified.
func performServiceCommand(command string) error {
var err error
switch command {
case "install":
err = installService()
case "remove":
err = removeService()
case "start":
err = startService()
case "stop":
err = controlService(svc.Stop, svc.Stopped)
default:
err = fmt.Errorf("invalid service command [%s]", command)
}
return err
}
// serviceMain checks whether we're being invoked as a service, and if so uses
// the service control manager to start the long-running server. A flag is
// returned to the caller so the application can determine whether to exit (when
// running as a service) or launch in normal interactive mode.
func serviceMain() (bool, error) {
// Don't run as a service if the user explicitly requested it. This is
// needed to run btcd on Windows in CI environments like Travis.
// We can't use the config struct to access the value because that's not
// parsed yet. But we add the flag to the struct anyway so the parser
// won't complain about it later.
noService := false
for _, arg := range os.Args {
if arg == "--nowinservice" {
noService = true
break
}
}
if noService {
return false, nil
}
// Don't run as a service if we're running interactively (or that can't
// be determined due to an error).
isInteractive, err := svc.IsAnInteractiveSession()
if err != nil {
return false, err
}
if isInteractive {
return false, nil
}
elog, err = eventlog.Open(svcName)
if err != nil {
return false, err
}
defer elog.Close()
err = svc.Run(svcName, &btcdService{})
if err != nil {
elog.Error(1, fmt.Sprintf("Service start failed: %v", err))
return true, err
}
return true, nil
}
// Set windows specific functions to real functions.
func init() {
runServiceCommand = performServiceCommand
winServiceMain = serviceMain
}