GODT-1977: fix launcher for v2 to v3 updates.

internal/updater/install_darwin.go

@@ -61,3 +61,7 @@ func (i *InstallerDarwin) InstallUpdate(_ *semver.Version, r io.Reader) error {
 
 	return syncFolders(oldBundle, newBundle)
 }
+
+func (i *InstallerDarwin) IsAlreadyInstalled(version *semver.Version) bool {
+	return false
+}

internal/updater/install_default.go

@@ -25,6 +25,7 @@ import (
 
 	"github.com/Masterminds/semver/v3"
 	"github.com/ProtonMail/proton-bridge/v2/internal/versioner"
+	"github.com/sirupsen/logrus"
 )
 
 type InstallerDefault struct {
@@ -40,3 +41,15 @@ func NewInstaller(versioner *versioner.Versioner) *InstallerDefault {
 func (i *InstallerDefault) InstallUpdate(version *semver.Version, r io.Reader) error {
 	return i.versioner.InstallNewVersion(version, r)
 }
+
+func (i *InstallerDefault) IsAlreadyInstalled(version *semver.Version) bool {
+	versions, err := i.versioner.ListVersions()
+	if err != nil {
+		logrus.WithField("version", version).
+			WithError(err).Error("Failed to determine whether version is installed")
+
+		return false
+	}
+
+	return versions.HasVersion(version)
+}

internal/updater/updater.go

@@ -30,8 +30,9 @@ import (
 )
 
 var (
-	ErrDownloadVerify = errors.New("failed to download or verify the update")
-	ErrInstall        = errors.New("failed to install the update")
+	ErrDownloadVerify         = errors.New("failed to download or verify the update")
+	ErrInstall                = errors.New("failed to install the update")
+	ErrUpdateAlreadyInstalled = errors.New("update is already installed")
 )
 
 type Downloader interface {
@@ -39,6 +40,7 @@ type Downloader interface {
 }
 
 type Installer interface {
+	IsAlreadyInstalled(*semver.Version) bool
 	InstallUpdate(*semver.Version, io.Reader) error
 }
 
@@ -84,6 +86,10 @@ func (u *Updater) GetVersionInfo(ctx context.Context, downloader Downloader, cha
 }
 
 func (u *Updater) InstallUpdate(ctx context.Context, downloader Downloader, update VersionInfo) error {
+	if u.installer.IsAlreadyInstalled(update.Version) {
+		return ErrUpdateAlreadyInstalled
+	}
+
 	b, err := downloader.DownloadAndVerify(
 		ctx,
 		u.verifier,