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|
package winlayers
import (
"archive/tar"
"context"
"io"
"runtime"
"strings"
"sync"
"github.com/containerd/containerd/archive"
"github.com/containerd/containerd/archive/compression"
"github.com/containerd/containerd/content"
"github.com/containerd/containerd/diff"
"github.com/containerd/containerd/images"
"github.com/containerd/containerd/mount"
cerrdefs "github.com/containerd/errdefs"
digest "github.com/opencontainers/go-digest"
ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
"github.com/pkg/errors"
)
func NewFileSystemApplierWithWindows(cs content.Provider, a diff.Applier) diff.Applier {
if runtime.GOOS == "windows" {
return a
}
return &winApplier{
cs: cs,
a: a,
}
}
type winApplier struct {
cs content.Provider
a diff.Applier
}
func (s *winApplier) Apply(ctx context.Context, desc ocispecs.Descriptor, mounts []mount.Mount, opts ...diff.ApplyOpt) (d ocispecs.Descriptor, err error) {
// HACK:, containerd doesn't know about vnd.docker.image.rootfs.diff.tar.zstd, but that
// media type is compatible w/ the oci type, so just lie and say it's the oci type
if desc.MediaType == images.MediaTypeDockerSchema2Layer+".zstd" {
desc.MediaType = ocispecs.MediaTypeImageLayerZstd
}
if !hasWindowsLayerMode(ctx) {
return s.apply(ctx, desc, mounts, opts...)
}
compressed, err := images.DiffCompression(ctx, desc.MediaType)
if err != nil {
return ocispecs.Descriptor{}, errors.Wrapf(cerrdefs.ErrNotImplemented, "unsupported diff media type: %v", desc.MediaType)
}
var ocidesc ocispecs.Descriptor
if err := mount.WithTempMount(ctx, mounts, func(root string) error {
ra, err := s.cs.ReaderAt(ctx, desc)
if err != nil {
return errors.Wrap(err, "failed to get reader from content store")
}
defer ra.Close()
r := content.NewReader(ra)
if compressed != "" {
ds, err := compression.DecompressStream(r)
if err != nil {
return err
}
defer ds.Close()
r = ds
}
digester := digest.Canonical.Digester()
rc := &readCounter{
r: io.TeeReader(r, digester.Hash()),
}
rc2, discard := filter(rc, func(hdr *tar.Header) bool {
if strings.HasPrefix(hdr.Name, "Files/") {
hdr.Name = strings.TrimPrefix(hdr.Name, "Files/")
hdr.Linkname = strings.TrimPrefix(hdr.Linkname, "Files/")
// TODO: could convert the windows PAX headers to xattr here to reuse
// the original ones in diff for parent directories and file modifications
return true
}
return false
})
if _, err := archive.Apply(ctx, root, rc2); err != nil {
discard(err)
return err
}
// Read any trailing data
if _, err := io.Copy(io.Discard, rc); err != nil {
discard(err)
return err
}
ocidesc = ocispecs.Descriptor{
MediaType: ocispecs.MediaTypeImageLayer,
Size: rc.c,
Digest: digester.Digest(),
}
return nil
}); err != nil {
return ocispecs.Descriptor{}, err
}
return ocidesc, nil
}
type readCounter struct {
r io.Reader
c int64
}
func (rc *readCounter) Read(p []byte) (n int, err error) {
n, err = rc.r.Read(p)
rc.c += int64(n)
return
}
func filter(in io.Reader, f func(*tar.Header) bool) (io.Reader, func(error)) {
pr, pw := io.Pipe()
rc := &readCanceler{Reader: in}
go func() {
tarReader := tar.NewReader(rc)
tarWriter := tar.NewWriter(pw)
pw.CloseWithError(func() error {
for {
h, err := tarReader.Next()
if err == io.EOF {
break
}
if err != nil {
return err
}
if f(h) {
if err := tarWriter.WriteHeader(h); err != nil {
return err
}
if h.Size > 0 {
//nolint:gosec // never read into memory
if _, err := io.Copy(tarWriter, tarReader); err != nil {
return err
}
}
} else if h.Size > 0 {
//nolint:gosec // never read into memory
if _, err := io.Copy(io.Discard, tarReader); err != nil {
return err
}
}
}
return tarWriter.Close()
}())
}()
discard := func(err error) {
rc.cancel(err)
pw.CloseWithError(err)
}
return pr, discard
}
type readCanceler struct {
mu sync.Mutex
io.Reader
err error
}
func (r *readCanceler) Read(b []byte) (int, error) {
r.mu.Lock()
if r.err != nil {
r.mu.Unlock()
return 0, r.err
}
n, err := r.Reader.Read(b)
r.mu.Unlock()
return n, err
}
func (r *readCanceler) cancel(err error) {
r.mu.Lock()
r.err = err
r.mu.Unlock()
}
|
