mirror of https://github.com/k3s-io/k3s
89 lines
2.0 KiB
Go
89 lines
2.0 KiB
Go
// Package ociwclayer provides functions for importing and exporting Windows
|
|
// container layers from and to their OCI tar representation.
|
|
package ociwclayer
|
|
|
|
import (
|
|
"archive/tar"
|
|
"context"
|
|
"io"
|
|
"path/filepath"
|
|
|
|
"github.com/Microsoft/go-winio/backuptar"
|
|
"github.com/Microsoft/hcsshim"
|
|
)
|
|
|
|
var driverInfo = hcsshim.DriverInfo{}
|
|
|
|
// ExportLayerToTar writes an OCI layer tar stream from the provided on-disk layer.
|
|
// The caller must specify the parent layers, if any, ordered from lowest to
|
|
// highest layer.
|
|
//
|
|
// The layer will be mounted for this process, so the caller should ensure that
|
|
// it is not currently mounted.
|
|
func ExportLayerToTar(ctx context.Context, w io.Writer, path string, parentLayerPaths []string) error {
|
|
err := hcsshim.ActivateLayer(driverInfo, path)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer func() {
|
|
_ = hcsshim.DeactivateLayer(driverInfo, path)
|
|
}()
|
|
|
|
// Prepare and unprepare the layer to ensure that it has been initialized.
|
|
err = hcsshim.PrepareLayer(driverInfo, path, parentLayerPaths)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
err = hcsshim.UnprepareLayer(driverInfo, path)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
r, err := hcsshim.NewLayerReader(driverInfo, path, parentLayerPaths)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
err = writeTarFromLayer(ctx, r, w)
|
|
cerr := r.Close()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
return cerr
|
|
}
|
|
|
|
func writeTarFromLayer(ctx context.Context, r hcsshim.LayerReader, w io.Writer) error {
|
|
t := tar.NewWriter(w)
|
|
for {
|
|
select {
|
|
case <-ctx.Done():
|
|
return ctx.Err()
|
|
default:
|
|
}
|
|
|
|
name, size, fileInfo, err := r.Next()
|
|
if err == io.EOF {
|
|
break
|
|
}
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if fileInfo == nil {
|
|
// Write a whiteout file.
|
|
hdr := &tar.Header{
|
|
Name: filepath.ToSlash(filepath.Join(filepath.Dir(name), whiteoutPrefix+filepath.Base(name))),
|
|
}
|
|
err := t.WriteHeader(hdr)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
} else {
|
|
err = backuptar.WriteTarFileFromBackupStream(t, r, name, size, fileInfo)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
}
|
|
}
|
|
return t.Close()
|
|
}
|