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|
package pkgtools
import (
"archive/tar"
"fmt"
"io"
"os"
"path"
"path/filepath"
"github.com/pkg/errors"
"golang.org/x/sys/unix"
)
type TarReader interface {
Next() (*tar.Header, error)
Read([]byte) (int, error)
}
const NewDirMod = 0755
func tarCreateBlockDev(target string, header *tar.Header) error {
mode := uint32(header.Mode & 07777)
mode |= unix.S_IFBLK
dev := unix.Mkdev(uint32(header.Devmajor), uint32(header.Devminor))
err := unix.Mknod(target, mode, int(dev))
return err
}
func tarCreateCharDev(target string, header *tar.Header) error {
mode := uint32(header.Mode & 07777)
mode |= unix.S_IFCHR
dev := unix.Mkdev(uint32(header.Devmajor), uint32(header.Devminor))
err := unix.Mknod(target, mode, int(dev))
return err
}
func tarCreateDir(target string) error {
err := os.MkdirAll(target, NewDirMod)
return err
}
func tarCreateFifo(target string, header *tar.Header) error {
mode := uint32(header.Mode & 07777)
mode |= unix.S_IFIFO
dev := unix.Mkdev(uint32(header.Devmajor), uint32(header.Devminor))
err := unix.Mknod(target, mode, int(dev))
return err
}
func tarCreateReg(target string, r io.Reader, header *tar.Header) error {
f, err := os.OpenFile(
target,
os.O_CREATE|os.O_RDWR,
os.FileMode(header.Mode),
)
if err != nil {
// it could be an error due to writing over a running executable.
err = os.Remove(target)
if err != nil {
return err
}
f, err = os.OpenFile(
target,
os.O_CREATE|os.O_RDWR,
os.FileMode(header.Mode),
)
if err != nil {
return err
}
}
defer f.Close()
// copy over contents
if _, err := io.Copy(f, r); err != nil {
return err
}
return nil
}
func tarCreateLink(root string, header *tar.Header) error {
oldName := filepath.Join(root, header.Linkname)
if filepath.IsAbs(header.Linkname) {
filepath.Join(root, oldName)
}
newName := filepath.Join(root, header.Name)
err := os.Link(oldName, newName)
if err != nil {
_ = os.Remove(newName)
err = os.Link(oldName, newName)
}
return err
}
func tarCreateSymlink(root string, header *tar.Header) error {
oldName := filepath.Join(root, header.Linkname)
if filepath.IsAbs(header.Linkname) {
filepath.Join(root, oldName)
}
newName := filepath.Join(root, header.Name)
err := os.Symlink(oldName, newName)
if err != nil {
_ = os.Remove(newName)
err = os.Symlink(oldName, newName)
}
return err
}
type TarFilter interface {
FilterTar(header *tar.Header, r io.Reader) error
}
type TarFilterFunc func(
header *tar.Header,
r io.Reader,
) error
func (f TarFilterFunc) FilterTar(h *tar.Header, r io.Reader) error {
return f(h, r)
}
type TarCfg struct {
Root string
Chown bool
Chmod bool
// Strict bails out when anything unexpected is encountered.
Strict bool
}
type TarExtracter struct {
cfg *TarCfg
}
func NewTarExtractor(cfg *TarCfg) *TarExtracter {
return &TarExtracter{cfg}
}
func (s *TarExtracter) FilterTar(
header *tar.Header,
r io.Reader,
) error {
target := path.Join(s.cfg.Root, header.Name)
if s.cfg.Strict {
if len(header.PAXRecords) > 0 {
return errors.Errorf(
"%s: contains unsupported PAXRecords, bailing out",
header.Name,
)
}
if len(header.Xattrs) > 0 {
return errors.Errorf(
"%s: contains unsupported extended attributes, bailing out",
header.Name,
)
}
}
var err error
switch header.Typeflag {
case tar.TypeBlock:
err = tarCreateBlockDev(target, header)
case tar.TypeChar:
err = tarCreateCharDev(target, header)
case tar.TypeFifo:
err = tarCreateFifo(target, header)
case tar.TypeDir:
err = tarCreateDir(target)
case tar.TypeReg:
err = tarCreateReg(target, r, header)
case tar.TypeLink:
err = tarCreateLink(s.cfg.Root, header)
case tar.TypeSymlink:
err = tarCreateSymlink(s.cfg.Root, header)
default:
err = errors.Errorf("unhandled file type '%c'", header.Typeflag)
}
if err != nil {
return errors.Wrap(err, "unpacking tar archive")
}
if s.cfg.Chown {
if err = os.Chown(target, header.Uid, header.Gid); err != nil {
fmt.Fprintln(os.Stderr, err)
}
}
if s.cfg.Chmod {
if err = os.Chmod(target, header.FileInfo().Mode()); err != nil {
fmt.Fprintln(os.Stderr, err)
}
}
return nil
}
func FilterTar(
r TarReader,
filters ...TarFilter,
) error {
for {
header, err := r.Next()
if err == io.EOF {
break
} else if err != nil {
return err
}
if header == nil {
continue
}
for _, f := range filters {
// TODO: how do we dup r?
err := f.FilterTar(header, r)
if err != nil {
return err
}
}
}
return nil
}
func ExtractTar(
cfg *TarCfg,
fp string,
) error {
f, err := os.Open(fp)
if err != nil {
return err
}
defer f.Close()
r := tar.NewReader(f)
err = FilterTar(r, NewTarExtractor(cfg))
return errors.Wrap(err, "extracting tar file")
}
|
