feat: boot.img.lz4

cmd/dkl-local-server/boot-img.go

@@ -0,0 +1,144 @@
+package main
+
+import (
+	"archive/tar"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"syscall"
+
+	"github.com/pierrec/lz4"
+)
+
+func buildBootImg(out io.Writer, ctx *renderContext) (err error) {
+	bootImg, err := ioutil.TempFile(os.TempDir(), "boot.img-")
+	if err != nil {
+		return
+	}
+	defer rmTempFile(bootImg)
+
+	// 2MB + 2GB + 2MB + 34 sectors
+	bootImg.Truncate(2<<30 + 4<<20 + 34*512)
+
+	// partition
+	err = run("sgdisk",
+		"--new=0:4096:+2G", "--typecode=0:EF00", "-c", "0:boot",
+		"--new=0:0:+2M", "--typecode=0:EF02", "-c", "0:BIOS-BOOT",
+		"--hybrid=1:2", "--print", bootImg.Name())
+	if err != nil {
+		return
+	}
+
+	err = setupBootImage(bootImg, ctx)
+	if err != nil {
+		return
+	}
+
+	// send the result
+	bootImg.Seek(0, os.SEEK_SET)
+
+	lz4Out := lz4.NewWriter(out)
+	io.Copy(lz4Out, bootImg)
+	lz4Out.Close()
+
+	return
+}
+
+func setupBootImage(bootImg *os.File, ctx *renderContext) (err error) {
+	devb, err := exec.Command("losetup", "--find", "--show", "--partscan", bootImg.Name()).CombinedOutput()
+	if err != nil {
+		return
+	}
+
+	dev := strings.TrimSpace(string(devb))
+	defer run("losetup", "-d", dev)
+
+	log.Print("device: ", dev)
+
+	err = run("mkfs.vfat", "-n", "DKLBOOT", dev+"p1")
+	if err != nil {
+		return
+	}
+
+	tempDir := bootImg.Name() + ".p1.mount"
+
+	err = os.Mkdir(tempDir, 0755)
+	if err != nil {
+		return
+	}
+
+	defer func() {
+		log.Print("Removing ", tempDir)
+		os.RemoveAll(tempDir)
+	}()
+
+	err = syscall.Mount(dev+"p1", tempDir, "vfat", 0, "")
+	if err != nil {
+		return
+	}
+
+	defer func() {
+		log.Print("Unmounting ", tempDir)
+		syscall.Unmount(tempDir, 0)
+	}()
+
+	// setup grub
+	err = run("/scripts/grub_install.sh", bootImg.Name(), dev, tempDir)
+	if err != nil {
+		return
+	}
+
+	// add system elements
+	tarOut, tarIn := io.Pipe()
+	go func() {
+		err2 := buildBootTar(tarIn, ctx)
+		tarIn.Close()
+		if err2 != nil {
+			err = err2
+		}
+	}()
+
+	defer tarOut.Close()
+
+	tarRd := tar.NewReader(tarOut)
+
+	for {
+		hdr, err := tarRd.Next()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return err
+		}
+
+		log.Print("tar: extracting ", hdr.Name)
+
+		outPath := filepath.Join(tempDir, hdr.Name)
+		os.MkdirAll(filepath.Dir(outPath), 0755)
+
+		f, err := os.Create(outPath)
+		if err != nil {
+			return err
+		}
+
+		_, err = io.Copy(f, tarRd)
+		f.Close()
+
+		if err != nil {
+			return err
+		}
+	}
+
+	return
+}
+
+func run(program string, args ...string) (err error) {
+	cmd := exec.Command(program, args...)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}