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package wclayer
import (
"io/ioutil"
"os"
"github.com/Microsoft/go-winio"
"github.com/Microsoft/hcsshim/internal/hcserror"
"github.com/sirupsen/logrus"
)
// ExportLayer will create a folder at exportFolderPath and fill that folder with
// the transport format version of the layer identified by layerId. This transport
// format includes any metadata required for later importing the layer (using
// ImportLayer), and requires the full list of parent layer paths in order to
// perform the export.
func ExportLayer(path string, exportFolderPath string, parentLayerPaths []string) (err error) {
title := "hcsshim::ExportLayer"
fields := logrus.Fields{
"path": path,
"exportFolderPath": exportFolderPath,
}
logrus.WithFields(fields).Debug(title)
defer func() {
if err != nil {
fields[logrus.ErrorKey] = err
logrus.WithFields(fields).Error(err)
} else {
logrus.WithFields(fields).Debug(title + " - succeeded")
}
}()
// Generate layer descriptors
layers, err := layerPathsToDescriptors(parentLayerPaths)
if err != nil {
return err
}
err = exportLayer(&stdDriverInfo, path, exportFolderPath, layers)
if err != nil {
return hcserror.New(err, title+" - failed", "")
}
return nil
}
type LayerReader interface {
Next() (string, int64, *winio.FileBasicInfo, error)
Read(b []byte) (int, error)
Close() error
}
// NewLayerReader returns a new layer reader for reading the contents of an on-disk layer.
// The caller must have taken the SeBackupPrivilege privilege
// to call this and any methods on the resulting LayerReader.
func NewLayerReader(path string, parentLayerPaths []string) (LayerReader, error) {
exportPath, err := ioutil.TempDir("", "hcs")
if err != nil {
return nil, err
}
err = ExportLayer(path, exportPath, parentLayerPaths)
if err != nil {
os.RemoveAll(exportPath)
return nil, err
}
return &legacyLayerReaderWrapper{newLegacyLayerReader(exportPath)}, nil
}
type legacyLayerReaderWrapper struct {
*legacyLayerReader
}
func (r *legacyLayerReaderWrapper) Close() error {
err := r.legacyLayerReader.Close()
os.RemoveAll(r.root)
return err
}
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