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