示例#1
0
func (app *App) UnlockDirectory() (err error) {
	if app.lockFile == nil {
		return nil
	}

	if !caravel.FileExists(app.lockFile.Name()) {
		return nil
	}

	log.Info("Releasing the API lock...")
	err = lockapi.UnlockFile(app.lockFile)
	if err != nil {
		return err
	}
	log.Notice("Lock released")

	log.Info("Closing lock file...")
	err = app.lockFile.Close()
	if err != nil {
		return err
	}
	log.Notice("Lock file closed")

	log.Info("Deleting lock file...")
	err = os.Remove(app.lockFile.Name())
	if err != nil {
		return err
	}
	log.Notice("Lock file deleted")

	app.lockFile = nil

	return nil
}
示例#2
0
func (app *App) GetReferenceDescriptor() (referenceDescriptor descriptors.AppDescriptor, err error) {
	if app.referenceDescriptorCached {
		return app.referenceDescriptor, nil
	}

	app.referenceDescriptorCached = true

	localDescriptor := app.GetLocalDescriptor()
	remoteDescriptor := app.GetRemoteDescriptor()

	if remoteDescriptor == nil && localDescriptor == nil {
		return nil, fmt.Errorf("Cannot run the application: it is not installed and cannot be downloaded")
	}

	if remoteDescriptor == nil {
		if localDescriptor.IsSkipUpdateCheck() {
			log.Info("The remote descriptor is missing as requested, so the local descriptor will be used")
		} else {
			log.Warning("The remote descriptor is missing, so the local descriptor will be used")
		}
		app.referenceDescriptor = localDescriptor
	} else if localDescriptor == nil {
		log.Notice("The local descriptor is missing, so the remote descriptor will be used")
		app.referenceDescriptor = remoteDescriptor
	} else if remoteDescriptor.GetAppVersion().NewerThan(localDescriptor.GetAppVersion()) {
		log.Notice("Switching to the remote descriptor, as it is more recent")
		app.referenceDescriptor = remoteDescriptor
	} else {
		log.Notice("Keeping the local descriptor, as the remote descriptor is NOT more recent")
		app.referenceDescriptor = localDescriptor
	}

	return app.referenceDescriptor, nil
}
示例#3
0
func (app *App) GetLocalDescriptor() (localDescriptor descriptors.AppDescriptor) {
	if app.localDescriptorCached {
		return app.localDescriptor
	}

	app.localDescriptorCached = true

	if !caravel.FileExists(app.localDescriptorPath) {
		log.Notice("The local descriptor is missing")
		return nil
	}

	log.Notice("The local descriptor has been found! Opening it...")
	localDescriptor, err := descriptors.NewAppDescriptorFromPath(app.localDescriptorPath)
	if err != nil {
		log.Warning(err.Error())
		return nil
	}
	log.Notice("Local descriptor ready")

	log.Debug("The local descriptor is: %#v", localDescriptor)

	app.localDescriptor = localDescriptor

	return localDescriptor
}
示例#4
0
func (app *App) installPackage(
	packageName string,
	settings config.Settings,
	progressCallback caravel.RetrievalProgressCallback) (err error) {

	remoteDescriptor := app.GetRemoteDescriptor()

	packageURL, err := remoteDescriptor.GetRemoteFileURL(packageName)
	if err != nil {
		return err
	}

	log.Debug("Creating package temp file...")
	packageTempFile, err := ioutil.TempFile(os.TempDir(), packageName)
	if err != nil {
		return err
	}
	packageTempFilePath := packageTempFile.Name()
	log.Debug("Package temp file created '%v'", packageTempFilePath)

	defer func() {
		packageTempFile.Close()

		log.Debug("Deleting package temp file: '%v'", packageTempFilePath)
		tempFileRemovalErr := os.Remove(packageTempFilePath)
		if tempFileRemovalErr != nil {
			log.Warning("Could not remove the package temp file! '%v'", tempFileRemovalErr)
		} else {
			log.Notice("Package temp file removed")
		}
	}()

	log.Info("Retrieving package: %v", packageURL)
	err = caravel.RetrieveChunksFromURL(packageURL, packageTempFile, settings.GetBufferSize(), progressCallback)
	if err != nil {
		return err
	}
	log.Notice("Package retrieved")

	log.Debug("Closing the package temp file...")
	packageTempFile.Close()
	if err != nil {
		return err
	}
	log.Notice("Package temp file closed")

	err = os.MkdirAll(app.filesDirectory, 0700)
	if err != nil {
		return err
	}

	log.Info("Extracting the package. Skipping levels: %v...", remoteDescriptor.GetSkipPackageLevels())
	err = caravel.ExtractZipSkipLevels(packageTempFilePath, app.filesDirectory, remoteDescriptor.GetSkipPackageLevels())
	if err != nil {
		return err
	}
	log.Notice("Package extracted")

	return nil
}
示例#5
0
func (app *App) GetRemoteDescriptor() (remoteDescriptor descriptors.AppDescriptor) {
	if app.remoteDescriptorCached {
		return app.remoteDescriptor
	}

	app.remoteDescriptorCached = true

	bootDescriptor := app.bootDescriptor
	localDescriptor := app.GetLocalDescriptor()

	var remoteDescriptorURL *url.URL
	var err error

	if localDescriptor != nil {
		if localDescriptor.IsSkipUpdateCheck() {
			log.Notice("Skipping update check, as requested by the local descriptor")
			return nil
		}

		remoteDescriptorURL, err = localDescriptor.GetRemoteFileURL(localDescriptor.GetDescriptorFileName())
	} else {
		remoteDescriptorURL, err = bootDescriptor.GetRemoteFileURL(bootDescriptor.GetDescriptorFileName())
	}

	if err != nil {
		log.Warning(err.Error())
		return nil
	}

	log.Notice("The remote descriptor's URL is: %v", remoteDescriptorURL)

	log.Info("Retrieving the remote descriptor...")
	remoteDescriptorBytes, err := caravel.RetrieveFromURL(remoteDescriptorURL)
	if err != nil {
		log.Warning(err.Error())
		return nil
	}
	log.Notice("Remote descriptor retrieved")

	log.Info("Opening the remote descriptor...")
	remoteDescriptor, err = descriptors.NewAppDescriptorFromBytes(remoteDescriptorBytes)
	if err != nil {
		log.Warning(err.Error())
		return nil
	}
	log.Notice("Remote descriptor ready")

	log.Debug("The remote descriptor is: %#v", remoteDescriptor)

	app.remoteDescriptor = remoteDescriptor

	return remoteDescriptor
}
示例#6
0
func (app *App) PrepareCommand(commandLine []string) (command *exec.Cmd) {
	if caravel.DirectoryExists(app.filesDirectory) {
		os.Chdir(app.filesDirectory)
		log.Notice("Files directory set as the current directory")
	} else {
		os.Chdir(app.Directory)
		log.Notice("App directory set as the current directory")
	}

	if len(commandLine) == 1 {
		return exec.Command(commandLine[0])
	}

	return exec.Command(commandLine[0], commandLine[1:]...)
}
示例#7
0
func (app *App) LockDirectory() (err error) {
	if app.lockFile != nil {
		return nil
	}

	lockFilePath := filepath.Join(app.Directory, lockFileName)

	log.Info("The lock file is: %v", lockFilePath)

	log.Info("Opening the lock file...")
	lockFile, err := os.OpenFile(lockFilePath, os.O_CREATE|os.O_TRUNC|os.O_RDWR, 0600)
	if err != nil {
		return err
	}

	log.Info("Obtaining the API lock...")
	err = lockapi.TryLockFile(lockFile)
	if err != nil {
		lockFile.Close()
		return err
	}
	log.Notice("Lock acquired")

	app.lockFile = lockFile

	return nil
}
示例#8
0
func runEngineWithGtk(launcher launchers.Launcher, bootDescriptorPath string) guiOutcomeStruct {
	log.Debug("Creating the GTK+ user interface...")

	userInterface, err := gtkui.NewGtkUserInterface(launcher)
	if err != nil {
		return guiOutcomeStruct{
			userInterface: nil,
			err:           err,
		}
	}

	log.Debug("User interface created")

	//----------------------------------------------------------------------------
	log.Info("Opening boot descriptor: '%v'...", bootDescriptorPath)

	bootDescriptor, err := descriptors.NewAppDescriptorFromPath(bootDescriptorPath)
	if err != nil {
		return guiOutcomeStruct{
			userInterface: userInterface,
			err:           err,
		}
	}

	log.Notice("Boot descriptor ready")
	//----------------------------------------------------------------------------

	log.Debug("Starting the launch process...")

	err = engine.Run(launcher, userInterface, bootDescriptor)
	return guiOutcomeStruct{
		userInterface: userInterface,
		err:           err,
	}
}
示例#9
0
func NewAppDescriptorFromBytes(descriptorBytes []byte) (descriptor AppDescriptor, err error) {
	basicDescriptor, err := createBasicDescriptor(descriptorBytes)
	if err != nil {
		return nil, err
	}

	descriptorVersion, err := versioning.ParseVersion(basicDescriptor.DescriptorVersion)
	if err != nil {
		return nil, fmt.Errorf("Invalid Descriptor Version: %v", err.Error())
	}

	switch descriptorVersion.Major {
	case 3:
		log.Notice("V3 descriptor found! Deserializing it")
		descriptor, err = createV3Descriptor(descriptorBytes)

	case 2:
	case 1:
		log.Notice("V1/V2 descriptor found! Deserializing it")
		descriptor, err = createV1V2Descriptor(descriptorBytes)

	default:
		return nil, fmt.Errorf("Unsupported descriptor version (%v). Please, consider updating MoonDeploy - your current version is %v.",
			descriptorVersion,
			moondeploy.Version)
	}

	err = descriptor.Init()
	if err != nil {
		return nil, err
	}

	err = validate(descriptor)
	if err != nil {
		return nil, err
	}

	return descriptor, nil
}
示例#10
0
/*
ServeDirectory activates a basic static web server on the given port, serving
from the given source directory.
A client can stop it by accessing its "/moondeploy.quit" path.
*/
func ServeDirectory(sourceDirectory string, port int) (err error) {
	fileServer := http.FileServer(http.Dir(sourceDirectory))
	http.Handle("/", fileServer)

	http.HandleFunc("/moondeploy.quit", func(http.ResponseWriter, *http.Request) {
		log.Notice("OK")
		os.Exit(v3.ExitCodeSuccess)
	})

	portString := ":" + strconv.Itoa(port)

	return http.ListenAndServe(portString, nil)
}
示例#11
0
func StartGUI(launcher launchers.Launcher, bootDescriptorPath string) (err error) {
	bootDescriptor, err := descriptors.NewAppDescriptorFromPath(bootDescriptorPath)
	if err != nil {
		return err
	}

	bashTerminal := terminals.NewBashTerminal()

	userInterface := termui.NewTerminalUserInterface(launcher, bashTerminal)

	result := engine.Run(launcher, userInterface, bootDescriptor)

	log.Notice("OK")

	return result
}
示例#12
0
func (app *App) CreateDesktopShortcut(launcher launchers.Launcher, referenceDescriptor descriptors.AppDescriptor) (err error) {
	desktopDir, err := caravel.GetUserDesktop()
	if err != nil {
		return err
	}

	if !caravel.DirectoryExists(desktopDir) {
		return fmt.Errorf("Expected desktop dir '%v' not found", desktopDir)
	}

	shortcutFileName := caravel.FormatFileName(referenceDescriptor.GetName()) + ".desktop"
	log.Debug("Shortcut file name: '%v'", shortcutFileName)

	shortcutFilePath := filepath.Join(desktopDir, shortcutFileName)

	log.Info("Creating desktop shortcut: '%v'...", shortcutFilePath)

	shortcutFile, err := os.OpenFile(shortcutFilePath, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0700)
	if err != nil {
		return err
	}
	defer func() {
		shortcutFile.Close()
		if err != nil {
			os.Remove(shortcutFilePath)
		}
	}()

	actualIconPath := app.GetActualIconPath(launcher)

	shortcutContent := fmt.Sprintf(linuxShortcutContent,
		referenceDescriptor.GetName(),
		referenceDescriptor.GetDescription(),
		launcher.GetExecutable(),
		app.GetLocalDescriptorPath(),
		actualIconPath)

	_, err = shortcutFile.Write([]byte(shortcutContent))
	if err != nil {
		return err
	}

	log.Notice("Desktop shortcut created")

	return nil
}
示例#13
0
func (app *App) CreateDesktopShortcut(launcher launchers.Launcher, referenceDescriptor descriptors.AppDescriptor) (err error) {
	desktopDir, err := caravel.GetUserDesktop()
	if err != nil {
		return err
	}

	if !caravel.DirectoryExists(desktopDir) {
		return fmt.Errorf("Expected desktop dir '%v' not found", desktopDir)
	}

	scriptFileName := caravel.FormatFileName(referenceDescriptor.GetName())
	log.Debug("Bash shortcut name: '%v'", scriptFileName)

	scriptFilePath := filepath.Join(desktopDir, scriptFileName)
	log.Info("Creating Bash shortcut: '%v'...", scriptFilePath)

	scriptFile, err := os.OpenFile(scriptFilePath, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0700)
	if err != nil {
		return err
	}
	defer func() {
		scriptFile.Close()

		if err != nil {
			os.Remove(scriptFilePath)
		}
	}()

	scriptContent := fmt.Sprintf(macScriptContentFormat,
		launcher.GetExecutable(),
		app.localDescriptorPath)

	_, err = scriptFile.Write([]byte(scriptContent))
	if err != nil {
		return err
	}

	log.Notice("Bash shortcut script created")

	return nil
}
示例#14
0
func (app *App) Launch(command *exec.Cmd, settings config.Settings, userInterface ui.UserInterface) (err error) {
	log.Info("Starting the app...")

	log.Debug("Hiding the user interface...")
	userInterface.Hide()
	log.Notice("User interface hidden")

	if settings.IsSkipAppOutput() {
		return command.Run()
	}
	var outputBytes []byte
	outputBytes, err = command.CombinedOutput()

	if outputBytes != nil && len(outputBytes) > 0 {
		log.Info("------------------------------")
		log.Info(string(outputBytes))
		log.Info("------------------------------")
	}

	return err
}
示例#15
0
func getActualBaseURL(descriptor AppDescriptor) *url.URL {
	var actualBaseURL *url.URL

	for _, searchStrategy := range actualBaseURLSearchStrategies {
		actualBaseURL = searchStrategy(descriptor)

		if actualBaseURL != nil {
			log.Notice("The actual base URL has been found by a search strategy!")
			break
		}
	}

	if actualBaseURL == nil {
		log.Debug("The actual base URL just matches the declared base URL")
		actualBaseURL = descriptor.GetDeclaredBaseURL()
	}

	actualBaseURLCache[descriptor.GetDeclaredBaseURL().String()] = actualBaseURL

	return actualBaseURL
}
示例#16
0
func (app *App) SaveReferenceDescriptor() (referenceDescriptorSaved bool) {
	referenceDescriptor, err := app.GetReferenceDescriptor()
	if err != nil {
		log.Warning("Cannot save the reference descriptor: %v", err)
		return false
	}

	log.Info("Saving the reference descriptor as the local descriptor...")
	referenceDescriptorBytes, err := referenceDescriptor.GetBytes()
	if err != nil {
		log.Error("Could not serialize the reference descriptor: %v", err)
		return false
	}

	err = ioutil.WriteFile(app.localDescriptorPath, referenceDescriptorBytes, 0600)
	if err != nil {
		log.Error("Could not save the reference descriptor: %v", err)
		return false
	}

	log.Notice("Reference descriptor saved")
	return true
}
示例#17
0
func StartGUI(launcher launchers.Launcher, bootDescriptorPath string) (err error) {
	log.Debug("Initializing GTK...")
	gtkui.InitGTK()
	log.Debug("GTK initialized")

	guiOutcomeChannel := make(chan guiOutcomeStruct)
	defer close(guiOutcomeChannel)

	go backgroundOrchestrator(launcher, bootDescriptorPath, guiOutcomeChannel)

	log.Debug("Starting GTK main loop...")
	gtk.Main()

	log.SetCallback(func(level logging.Level, message string) {})
	log.Debug("GTK main loop terminated")

	select {
	case guiOutcome := <-guiOutcomeChannel:
		log.Debug("Outcome retrieved from the GUI channel")

		if guiOutcome.userInterface != nil && guiOutcome.userInterface.IsClosedByUser() {
			return &engine.ExecutionCanceled{}
		}

		err = guiOutcome.err
		if err != nil {
			log.Warning("Err is: %v", err)
			return err
		}

		log.Notice("OK")
		return nil
	default:
		log.Debug("The user has manually closed the program")
		return &engine.ExecutionCanceled{}
	}
}
示例#18
0
/*
Run is the entry point you must employ to create a custom installer, for example to
employ custom settings or a brand-new user interface, based on any technology
*/
func Run(
	launcher launchers.Launcher,
	userInterface ui.UserInterface,
	bootDescriptor descriptors.AppDescriptor) (err error) {

	settings := launcher.GetSettings()

	//----------------------------------------------------------------------------

	setupUserInterface(launcher, userInterface)
	defer dismissUserInterface(userInterface)

	//----------------------------------------------------------------------------

	userInterface.SetHeader("Performing startup operations")

	log.Debug("The boot descriptor is: %#v", bootDescriptor)

	//----------------------------------------------------------------------------

	userInterface.SetApp(bootDescriptor.GetName())

	//----------------------------------------------------------------------------

	appGallery := apps.NewAppGallery(settings.GetGalleryDirectory())
	log.Debug("The app gallery is: %#v", appGallery)

	//----------------------------------------------------------------------------

	log.Info("Resolving the app...")
	app, err := appGallery.GetApp(bootDescriptor)
	if err != nil {
		return err
	}
	log.Notice("The app directory is: '%v'", app.Directory)

	log.Debug("App is: %#v", app)

	firstRun := !app.DirectoryExists()
	log.Debug("Is this a first run for the app? %v", firstRun)

	//----------------------------------------------------------------------------

	if firstRun {
		log.Info("Now asking the user if the app can run...")

		canRun := app.CanPerformFirstRun(userInterface)
		if !canRun {
			return &ExecutionCanceled{}
		}

		log.Debug("The user agreed to proceed")

		log.Info("Ensuring the app dir is available...")
		err = app.EnsureDirectory()
		if err != nil {
			return err
		}
		log.Notice("App dir available")
	}

	//----------------------------------------------------------------------------

	log.Info("Locking the app dir...")
	err = app.LockDirectory()
	if err != nil {
		return err
	}
	defer func() {
		unlockErr := app.UnlockDirectory()
		if unlockErr != nil {
			log.Warning(unlockErr.Error())
		}
	}()

	log.Notice("App dir locked")

	//----------------------------------------------------------------------------

	log.Info("Checking for conflicting local descriptors...")
	err = app.CheckForConflictingLocalDescriptors()
	if err != nil {
		return err
	}
	log.Notice("No conflicting local descriptors found")

	//----------------------------------------------------------------------------

	log.Info("Resolving the local descriptor...")
	localDescriptor := app.GetLocalDescriptor()

	startedWithLocalDescriptor := localDescriptor != nil
	log.Debug("Started with local descriptor? %v", startedWithLocalDescriptor)

	if startedWithLocalDescriptor {
		log.Info("Checking that local descriptor and boot descriptor actually match...")
		err = descriptors.CheckDescriptorMatch(localDescriptor, bootDescriptor)
		if err != nil {
			return err
		}
		log.Notice("The descriptors match correctly")
	}

	//----------------------------------------------------------------------------

	log.Info("Resolving the remote descriptor...")
	remoteDescriptor := app.GetRemoteDescriptor()

	if remoteDescriptor != nil {
		log.Info("Checking that remote descriptor and boot descriptor actually match...")
		err = descriptors.CheckDescriptorMatch(remoteDescriptor, bootDescriptor)
		if err != nil {
			return err
		}
		log.Notice("The descriptors match correctly")
	}

	//----------------------------------------------------------------------------

	log.Info("Now choosing the reference descriptor...")
	referenceDescriptor, err := app.GetReferenceDescriptor()
	if err != nil {
		return err
	}
	log.Notice("Reference descriptor chosen")

	log.Debug("The reference descriptor is: %#v", referenceDescriptor)

	//----------------------------------------------------------------------------

	err = referenceDescriptor.CheckRequirements()
	if err != nil {
		return err
	}

	//----------------------------------------------------------------------------

	userInterface.SetApp(referenceDescriptor.GetTitle())

	//----------------------------------------------------------------------------

	log.Info("Resolving the OS-specific app command line...")
	commandLine := referenceDescriptor.GetCommandLine()
	log.Notice("Command line resolved")

	log.Debug("Command line is: %v", commandLine)

	//----------------------------------------------------------------------------

	err = app.CheckFiles(settings, userInterface)
	if err != nil {
		return err
	}

	//----------------------------------------------------------------------------

	userInterface.SetHeader("Preparing the command...")

	log.Info("Creating the command...")
	command := app.PrepareCommand(commandLine)
	log.Notice("Command created")

	log.Debug("Command path: %v", command.Path)
	log.Debug("Command arguments: %v", command.Args)

	//----------------------------------------------------------------------------

	referenceDescriptorSaved := app.SaveReferenceDescriptor()

	if !startedWithLocalDescriptor && referenceDescriptorSaved {
		if userInterface.AskForDesktopShortcut(referenceDescriptor) {
			log.Info("Creating desktop shortcut...")

			err = app.CreateDesktopShortcut(launcher, referenceDescriptor)
			if err != nil {
				log.Warning("Could not create desktop shortcut: %v", err)
			} else {
				log.Notice("Desktop shortcut created")
			}
		} else {
			log.Info("The user refused to create a desktop shortcut")
		}
	}

	//----------------------------------------------------------------------------

	app.UnlockDirectory()

	//----------------------------------------------------------------------------

	userInterface.SetHeader("Launching the application")
	userInterface.SetStatus("")

	return app.Launch(command, settings, userInterface)
}
示例#19
0
func GetGitHubDescriptorInfo(baseURL *url.URL, descriptorFileName string) *GitHubDescriptorInfo {
	projectParams := latestVersionURLRegex.FindStringSubmatch(baseURL.String())
	if projectParams == nil {
		log.Debug("The URL does not reference a 'latest' release on GitHub")
		return nil
	}
	log.Debug("The URL references a 'latest' release on GitHub")

	gitHubUser := projectParams[1]
	gitHubRepo := projectParams[2]

	apiLatestVersionURL, err := url.Parse(fmt.Sprintf(
		apiLatestVersionURLTemplate,
		gitHubUser,
		gitHubRepo))
	if err != nil {
		log.Warning(err.Error())
		return nil
	}

	log.Debug("Calling GitHub's API, at '%v'...", apiLatestVersionURL)

	apiResponseBytes, err := caravel.RetrieveFromURL(apiLatestVersionURL)
	if err != nil {
		log.Warning(err.Error())
		return nil
	}
	log.Debug("API returned OK")

	log.Debug("Deserializing the API response...")
	var latestVersionResponse latestVersionResponse
	err = json.Unmarshal(apiResponseBytes, &latestVersionResponse)
	if err != nil {
		log.Warning(err.Error())
		return nil
	}
	log.Debug("Response correctly deserialized: %#v", latestVersionResponse)

	log.Debug("Now processing the response fields...")

	result := &GitHubDescriptorInfo{}

	for _, asset := range latestVersionResponse.Assets {
		if asset.Name == descriptorFileName {
			result.DescriptorURL, err = url.Parse(asset.BrowserDownloadURL)
			if err != nil {
				log.Warning("Error while parsing the BrowserDownloadURL: %v", err.Error())
				return nil
			}
			break
		}
	}

	if result.DescriptorURL == nil {
		log.Warning("The app descriptor ('%v') could not be found as an asset of the latest release", descriptorFileName)
		return nil
	}

	tagComponents := tagRegex.FindStringSubmatch(latestVersionResponse.TagName)
	if tagComponents == nil {
		log.Warning("GitHub's release tag must be in the format: <any string, even empty><VERSION>, not '%v'", latestVersionResponse.TagName)
		return nil
	}

	result.Version, err = versioning.ParseVersion(tagComponents[1])
	if err != nil {
		log.Warning("Error while parsing the version: %v", err.Error())
		return nil
	}

	log.Notice("Response fields correctly processed")

	return result
}
示例#20
0
func (app *App) CheckFiles(
	settings config.Settings,
	userInterface ui.UserInterface) (err error) {

	localDescriptor := app.GetLocalDescriptor()
	remoteDescriptor := app.GetRemoteDescriptor()

	if remoteDescriptor == nil {
		log.Notice("Skipping file check, as the remote descriptor is missing")
		return nil
	}

	userInterface.SetHeader("Checking the app files")
	log.Notice("Computing differences...")

	packagesToUpdate := app.getPackagesToUpdate()

	if len(packagesToUpdate) == 0 {
		log.Notice("All the packages are up-to-date")
		return nil
	}

	if localDescriptor != nil && caravel.FileExists(app.GetLocalDescriptorPath()) {
		log.Info("Deleting the local descriptor before starting the update process...")
		err = os.Remove(app.GetLocalDescriptorPath())
		if err != nil {
			return err
		}
		log.Notice("Local descriptor deleted")
	}

	retrieveAllPackages := (len(packagesToUpdate) == len(remoteDescriptor.GetPackageVersions()))
	log.Notice("Must retrieve all the remote packages? %v", retrieveAllPackages)

	if retrieveAllPackages {
		log.Info("Removing app files dir...")
		err = os.RemoveAll(app.filesDirectory)
		if err != nil {
			return err
		}
		log.Notice("App files dir removed")
	}

	for packageIndex, packageName := range packagesToUpdate {
		userInterface.SetHeader(
			fmt.Sprintf("Updating package %v of %v: %v",
				packageIndex+1,
				len(packagesToUpdate),
				packageName))

		log.Notice("Downloading %v...", packageName)

		err = app.installPackage(
			packageName,
			settings,
			func(retrievedSize int64, totalSize int64) {
				log.Notice("Retrieved: %v / %v bytes", retrievedSize, totalSize)
				userInterface.SetProgress(float64(retrievedSize) / float64(totalSize))
			})
		if err != nil {
			return err
		}
	}

	log.Notice("App files checked")
	return nil
}