114 lines
2.7 KiB
Go
114 lines
2.7 KiB
Go
package chrootarchive
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import (
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"bytes"
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"encoding/json"
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"flag"
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"path/filepath"
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"runtime"
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"strings"
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"syscall"
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"github.com/docker/docker/pkg/archive"
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"github.com/docker/docker/pkg/reexec"
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)
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var chrootArchiver = &archive.Archiver{Untar}
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func chroot(path string) error {
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if err := syscall.Chroot(path); err != nil {
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return err
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}
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return syscall.Chdir("/")
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}
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func untar() {
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runtime.LockOSThread()
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flag.Parse()
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if err := chroot(flag.Arg(0)); err != nil {
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fatal(err)
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}
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var options *archive.TarOptions
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if err := json.NewDecoder(strings.NewReader(flag.Arg(1))).Decode(&options); err != nil {
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fatal(err)
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}
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if err := archive.Unpack(os.Stdin, "/", options); err != nil {
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fatal(err)
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}
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// fully consume stdin in case it is zero padded
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if _, err := ioutil.ReadAll(os.Stdin); err != nil {
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fatal(err)
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}
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os.Exit(0)
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}
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func Untar(tarArchive io.Reader, dest string, options *archive.TarOptions) error {
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if tarArchive == nil {
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return fmt.Errorf("Empty archive")
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}
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if options == nil {
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options = &archive.TarOptions{}
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}
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if options.Excludes == nil {
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options.Excludes = []string{}
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}
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var (
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buf bytes.Buffer
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enc = json.NewEncoder(&buf)
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)
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if err := enc.Encode(options); err != nil {
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return fmt.Errorf("Untar json encode: %v", err)
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}
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if _, err := os.Stat(dest); os.IsNotExist(err) {
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if err := os.MkdirAll(dest, 0777); err != nil {
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return err
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}
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}
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dest = filepath.Clean(dest)
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decompressedArchive, err := archive.DecompressStream(tarArchive)
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if err != nil {
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return err
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}
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defer decompressedArchive.Close()
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cmd := reexec.Command("docker-untar", dest, buf.String())
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cmd.Stdin = decompressedArchive
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out, err := cmd.CombinedOutput()
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if err != nil {
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return fmt.Errorf("Untar %s %s", err, out)
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}
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return nil
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}
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func TarUntar(src, dst string) error {
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return chrootArchiver.TarUntar(src, dst)
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}
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// CopyWithTar creates a tar archive of filesystem path `src`, and
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// unpacks it at filesystem path `dst`.
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// The archive is streamed directly with fixed buffering and no
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// intermediary disk IO.
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func CopyWithTar(src, dst string) error {
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return chrootArchiver.CopyWithTar(src, dst)
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}
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// CopyFileWithTar emulates the behavior of the 'cp' command-line
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// for a single file. It copies a regular file from path `src` to
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// path `dst`, and preserves all its metadata.
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//
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// If `dst` ends with a trailing slash '/', the final destination path
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// will be `dst/base(src)`.
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func CopyFileWithTar(src, dst string) (err error) {
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return chrootArchiver.CopyFileWithTar(src, dst)
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}
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// UntarPath is a convenience function which looks for an archive
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// at filesystem path `src`, and unpacks it at `dst`.
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func UntarPath(src, dst string) error {
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return chrootArchiver.UntarPath(src, dst)
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}
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