forked from oras-project/oras
/
utils.go
164 lines (150 loc) · 3.64 KB
/
utils.go
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package content
import (
"archive/tar"
"compress/gzip"
"fmt"
"io"
"os"
"path/filepath"
"strings"
digest "github.com/opencontainers/go-digest"
ocispec "github.com/opencontainers/image-spec/specs-go/v1"
"github.com/pkg/errors"
)
// ResolveName resolves name from descriptor
func ResolveName(desc ocispec.Descriptor) (string, bool) {
name, ok := desc.Annotations[ocispec.AnnotationTitle]
return name, ok
}
// tarDirectory walks the directory specified by path, and tar those files with a new
// path prefix.
func tarDirectory(root, prefix string, w io.Writer) error {
tw := tar.NewWriter(w)
defer tw.Close()
if err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
if err != nil {
return err
}
// Rename path
name, err := filepath.Rel(root, path)
if err != nil {
return err
}
name = filepath.Join(prefix, name)
name = filepath.ToSlash(name)
// Generate header
var link string
mode := info.Mode()
if mode&os.ModeSymlink != 0 {
if link, err = os.Readlink(path); err != nil {
return err
}
}
header, err := tar.FileInfoHeader(info, link)
if err != nil {
return errors.Wrap(err, path)
}
header.Name = name
header.Uid = 0
header.Gid = 0
header.Uname = ""
header.Gname = ""
// Write file
if err := tw.WriteHeader(header); err != nil {
return errors.Wrap(err, "tar")
}
if mode.IsRegular() {
file, err := os.Open(path)
if err != nil {
return err
}
defer file.Close()
if _, err := io.Copy(tw, file); err != nil {
return errors.Wrap(err, path)
}
}
return nil
}); err != nil {
return err
}
return nil
}
// extractTarDirectory extracts tar file to a directory specified by the `root`
// parameter. The file name prefix is ensured to be the string specified by the
// `prefix` parameter and is trimmed.
func extractTarDirectory(root, prefix string, r io.Reader) error {
tr := tar.NewReader(r)
for {
header, err := tr.Next()
if err != nil {
if err == io.EOF {
return nil
}
return err
}
// Name check
name := header.Name
path, err := filepath.Rel(prefix, name)
if err != nil {
return err
}
if strings.HasPrefix(path, "../") {
return fmt.Errorf("%q does not have prefix %q", name, prefix)
}
path = filepath.Join(root, path)
// Create content
switch header.Typeflag {
case tar.TypeReg:
err = writeFile(path, tr, header.FileInfo().Mode())
case tar.TypeDir:
err = os.MkdirAll(path, header.FileInfo().Mode())
case tar.TypeLink:
err = os.Link(header.Linkname, path)
case tar.TypeSymlink:
err = os.Symlink(header.Linkname, path)
default:
continue // Non-regular files are skipped
}
if err != nil {
return err
}
// Change access time and modification time if possible (error ignored)
os.Chtimes(path, header.AccessTime, header.ModTime)
}
}
func writeFile(path string, r io.Reader, perm os.FileMode) error {
file, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
if err != nil {
return err
}
defer file.Close()
_, err = io.Copy(file, r)
return err
}
func extractTarGzip(root, prefix, filename, checksum string) error {
file, err := os.Open(filename)
if err != nil {
return err
}
defer file.Close()
zr, err := gzip.NewReader(file)
if err != nil {
return err
}
defer zr.Close()
var r io.Reader = zr
var verifier digest.Verifier
if checksum != "" {
if digest, err := digest.Parse(checksum); err == nil {
verifier = digest.Verifier()
r = io.TeeReader(r, verifier)
}
}
if err := extractTarDirectory(root, prefix, r); err != nil {
return err
}
if verifier != nil && !verifier.Verified() {
return errors.New("content digest mismatch")
}
return nil
}