172 lines
2.8 KiB
Go
172 lines
2.8 KiB
Go
package main
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import (
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"archive/tar"
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"compress/gzip"
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"fmt"
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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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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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io.Copy(out, bootImg)
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return
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}
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func buildBootImgLZ4(out io.Writer, ctx *renderContext) (err error) {
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lz4Out := lz4.NewWriter(out)
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if err = buildBootImg(lz4Out, ctx); err != nil {
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return
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}
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lz4Out.Close()
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return
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}
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func buildBootImgGZ(out io.Writer, ctx *renderContext) (err error) {
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gzOut := gzip.NewWriter(out)
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if err = buildBootImg(gzOut, ctx); err != nil {
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return
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}
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gzOut.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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path, err := ctx.distFetch("grub-support", "1.0.0")
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if err != nil {
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return
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}
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baseImage, err := os.Open(path)
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if err != nil {
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return
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}
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defer baseImage.Close()
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baseImageGz, err := gzip.NewReader(baseImage)
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if err != nil {
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return
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}
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defer baseImageGz.Close()
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_, err = io.Copy(bootImg, baseImageGz)
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if err != nil {
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return
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}
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log.Print("running losetup...")
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cmd := exec.Command("losetup", "--find", "--show", "--partscan", bootImg.Name())
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cmd.Stderr = os.Stderr
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devb, err := cmd.Output()
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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 func() {
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log.Print("detaching ", dev)
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run("losetup", "-d", dev)
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}()
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log.Print("device: ", dev)
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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 fmt.Errorf("failed to mount %s to %s: %v", dev+"p1", tempDir, err)
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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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// 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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