Add /usr/bin/unudhcpd to initfs (MR 13)

This will replace the busybox dhcp server.

With this change, mkinitfs depends on the 'unudhcpd' packge in Alpine to
provide the binary at /usr/bin/unudhcpd.

.gitlab-ci.yml

@@ -31,7 +31,7 @@ gofmt linting:
     - apk -q update --repository http://dl-4.alpinelinux.org/alpine/edge/testing
     - apk -q add --repository http://dl-4.alpinelinux.org/alpine/edge/testing go staticcheck
   script:
-    - .gitlab-ci/check_linting.sh
+    - .ci/check_linting.sh
 
 build:
   stage: build

main.go

@@ -86,18 +86,29 @@ func bootDeploy(workDir string, outDir string) error {
 	if len(kernels) == 0 {
 		return errors.New("Unable to find any kernels at " + filepath.Join(outDir, "vmlinuz*"))
 	}
-	kernFile, err := os.Open(kernels[0])
+
+	// Pick a kernel that does not have suffixes added by boot-deploy
+	var kernFile string
+	for _, f := range kernels {
+		if strings.HasSuffix(f, "-dtb") || strings.HasSuffix(f, "-mtk") {
+			continue
+		}
+		kernFile = f
+		break
+	}
+
+	kernFd, err := os.Open(kernFile)
 	if err != nil {
 		return err
 	}
-	defer kernFile.Close()
+	defer kernFd.Close()
 
 	kernFileCopy, err := os.Create(filepath.Join(workDir, "vmlinuz"))
 	if err != nil {
 		return err
 	}
 
-	if _, err = io.Copy(kernFileCopy, kernFile); err != nil {
+	if _, err = io.Copy(kernFileCopy, kernFd); err != nil {
 		return err
 	}
 	kernFileCopy.Close()
@@ -403,6 +414,7 @@ func getInitfsFiles(files misc.StringSet, devinfo deviceinfo.DeviceInfo) error {
 		"/usr/sbin/telnetd":   false,
 		"/sbin/kpartx":        false,
 		"/etc/deviceinfo":     false,
+		"/usr/bin/unudhcpd":   false,
 	}
 
 	// Hook files & scripts