Upgrade pmctl to only do a self upgrade when the update is already available

pmctl/upgrade.go

@@ -13,7 +13,7 @@ import (
 
 func checkForUpgrade() (update *updates.File) {
 	info := info.GetInfo()
-	file, err := getFile("pmctl/pmctl")
+	file, err := updates.GetLocalPlatformFile("pmctl/pmctl")
 	if err != nil {
 		return nil
 	}

updates/get.go

@@ -13,6 +13,7 @@ import (
 
 var (
 	ErrNotFound = errors.New("the requested file could not be found")
+	ErrNotAvailableLocally = errors.New("the requested file is not available locally")
 )
 
 // GetPlatformFile returns the latest platform specific file identified by the given identifier.
@@ -21,13 +22,28 @@ func GetPlatformFile(identifier string) (*File, error) {
 	// From https://golang.org/pkg/runtime/#GOARCH
 	// GOOS is the running program's operating system target: one of darwin, freebsd, linux, and so on.
 	// GOARCH is the running program's architecture target: one of 386, amd64, arm, s390x, and so on.
-	return loadOrFetchFile(identifier)
+	return loadOrFetchFile(identifier, true)
+}
+
+// GetLocalPlatformFile returns the latest platform specific file identified by the given identifier, that is available locally.
+func GetLocalPlatformFile(identifier string) (*File, error) {
+	identifier = path.Join(fmt.Sprintf("%s_%s", runtime.GOOS, runtime.GOARCH), identifier)
+	// From https://golang.org/pkg/runtime/#GOARCH
+	// GOOS is the running program's operating system target: one of darwin, freebsd, linux, and so on.
+	// GOARCH is the running program's architecture target: one of 386, amd64, arm, s390x, and so on.
+	return loadOrFetchFile(identifier, false)
 }
 
 // GetFile returns the latest generic file identified by the given identifier.
 func GetFile(identifier string) (*File, error) {
 	identifier = path.Join("all", identifier)
-	return loadOrFetchFile(identifier)
+	return loadOrFetchFile(identifier, true)
+}
+
+// GetLocalFile returns the latest generic file identified by the given identifier, that is available locally.
+func GetLocalFile(identifier string) (*File, error) {
+	identifier = path.Join("all", identifier)
+	return loadOrFetchFile(identifier, false)
 }
 
 func getLatestFilePath(identifier string) (versionedFilePath, version string, stable bool, ok bool) {
@@ -49,7 +65,7 @@ func getLatestFilePath(identifier string) (versionedFilePath, version string, st
 	return GetVersionedPath(identifier, version), version, false, true
 }
 
-func loadOrFetchFile(identifier string) (*File, error) {
+func loadOrFetchFile(identifier string, fetch bool) (*File, error) {
 	versionedFilePath, version, stable, ok := getLatestFilePath(identifier)
 	if !ok {
 		// TODO: if in development mode, search updates dir for sideloaded apps
@@ -70,6 +86,10 @@ func loadOrFetchFile(identifier string) (*File, error) {
 		return nil, fmt.Errorf("could not prepare tmp directory for download: %s", err)
 	}
 
+	if (!fetch) {
+		return nil, ErrNotAvailableLocally
+	}
+
 	// download file
 	log.Tracef("updates: starting download of %s", versionedFilePath)
 	for tries := 0; tries < 5; tries++ {

updates/updater.go

@@ -23,9 +23,14 @@ func updater() {
 
 func CheckForUpdates() error {
 
+	// be sure that pmctl is part of the "used" updates
+	_, err := GetLocalFile("pmctl/pmctl")
+	if err != nil {
+		log.Errorf("updates: failed to mark pmctl/pmctl as used to ensure updates: %s", err)
+	}
+
 	// download new index
 	var data []byte
-	var err error
 	for tries := 0; tries < 3; tries++ {
 		data, err = fetchData("stable.json", tries)
 		if err == nil {