do a quick arch check to ensure both chosen arch && user program matc…

…hes (#1676)

* do a quick arch check to ensure both chosen arch && user program matches

* .

fs/manifest.go

@@ -51,8 +51,26 @@ func (m *Manifest) AddNetworkConfig(networkConfig *ManifestNetworkConfig) {
 	m.root["ip6addr"] = networkConfig.IPv6
 }
 
+// b7 = 183 = arm; 3e = 62 = x86
+func archCheck(imgpath string) string {
+	f, err := os.Open(imgpath)
+	if err != nil {
+		fmt.Println(err)
+	}
+	defer f.Close()
+
+	h := make([]byte, 19)
+	_, err = f.Read(h)
+
+	if h[18] == 183 {
+		return "arm"
+	}
+
+	return "amd64"
+}
+
 // AddUserProgram adds user program
-func (m *Manifest) AddUserProgram(imgpath string) (err error) {
+func (m *Manifest) AddUserProgram(imgpath string, arm bool) (err error) {
 	parts := strings.Split(imgpath, "/")
 	if parts[0] == "." {
 		parts = parts[1:]
@@ -62,6 +80,15 @@ func (m *Manifest) AddUserProgram(imgpath string) (err error) {
 	if filepath.IsAbs(imgpath) {
 		imgpath = filepath.Join(m.targetRoot, imgpath)
 	}
+
+	fmt.Printf("adding user program of %s\n", imgpath)
+	a := archCheck(imgpath)
+	if arm && a != "arm" || !arm && a == "arm" {
+		fmt.Printf("you are trying to mix %s [%s] with the wrong kernel\n", imgpath, a)
+		fmt.Printf("try re-creating the image with --arch=")
+		os.Exit(1)
+	}
+
 	err = m.AddFile(program, imgpath)
 	if err != nil {
 		return

lepton/image.go

@@ -387,13 +387,14 @@ func BuildManifest(c *types.Config) (*fs.Manifest, error) {
 
 	m := fs.NewManifest(c.TargetRoot)
 
+	arm := false
 	if strings.Contains(c.Kernel, "arm") {
-		addCommonFilesToManifest(m, true)
-	} else {
-		addCommonFilesToManifest(m, false)
+		arm = true
 	}
 
-	err = m.AddUserProgram(c.Program)
+	addCommonFilesToManifest(m, arm)
+
+	err = m.AddUserProgram(c.Program, arm)
 	if err != nil {
 		return nil, err
 	}