1 files changed, 156 insertions, 0 deletions
diff --git a/vendor/github.com/Microsoft/hcsshim/exportlayer.go b/vendor/github.com/Microsoft/hcsshim/exportlayer.go
new file mode 100644
index 000000000..d7025f20b
--- /dev/null
+++ b/vendor/github.com/Microsoft/hcsshim/exportlayer.go
@@ -0,0 +1,156 @@
+package hcsshim
+
+import (
+	"io"
+	"io/ioutil"
+	"os"
+	"syscall"
+
+	"github.com/Microsoft/go-winio"
+	"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(info DriverInfo, layerId string, exportFolderPath string, parentLayerPaths []string) error {
+	title := "hcsshim::ExportLayer "
+	logrus.Debugf(title+"flavour %d layerId %s folder %s", info.Flavour, layerId, exportFolderPath)
+
+	// Generate layer descriptors
+	layers, err := layerPathsToDescriptors(parentLayerPaths)
+	if err != nil {
+		return err
+	}
+
+	// Convert info to API calling convention
+	infop, err := convertDriverInfo(info)
+	if err != nil {
+		logrus.Error(err)
+		return err
+	}
+
+	err = exportLayer(&infop, layerId, exportFolderPath, layers)
+	if err != nil {
+		err = makeErrorf(err, title, "layerId=%s flavour=%d folder=%s", layerId, info.Flavour, exportFolderPath)
+		logrus.Error(err)
+		return err
+	}
+
+	logrus.Debugf(title+"succeeded flavour=%d layerId=%s folder=%s", info.Flavour, layerId, exportFolderPath)
+	return nil
+}
+
+type LayerReader interface {
+	Next() (string, int64, *winio.FileBasicInfo, error)
+	Read(b []byte) (int, error)
+	Close() error
+}
+
+// FilterLayerReader provides an interface for extracting the contents of an on-disk layer.
+type FilterLayerReader struct {
+	context uintptr
+}
+
+// Next reads the next available file from a layer, ensuring that parent directories are always read
+// before child files and directories.
+//
+// Next returns the file's relative path, size, and basic file metadata. Read() should be used to
+// extract a Win32 backup stream with the remainder of the metadata and the data.
+func (r *FilterLayerReader) Next() (string, int64, *winio.FileBasicInfo, error) {
+	var fileNamep *uint16
+	fileInfo := &winio.FileBasicInfo{}
+	var deleted uint32
+	var fileSize int64
+	err := exportLayerNext(r.context, &fileNamep, fileInfo, &fileSize, &deleted)
+	if err != nil {
+		if err == syscall.ERROR_NO_MORE_FILES {
+			err = io.EOF
+		} else {
+			err = makeError(err, "ExportLayerNext", "")
+		}
+		return "", 0, nil, err
+	}
+	fileName := convertAndFreeCoTaskMemString(fileNamep)
+	if deleted != 0 {
+		fileInfo = nil
+	}
+	if fileName[0] == '\\' {
+		fileName = fileName[1:]
+	}
+	return fileName, fileSize, fileInfo, nil
+}
+
+// Read reads from the current file's Win32 backup stream.
+func (r *FilterLayerReader) Read(b []byte) (int, error) {
+	var bytesRead uint32
+	err := exportLayerRead(r.context, b, &bytesRead)
+	if err != nil {
+		return 0, makeError(err, "ExportLayerRead", "")
+	}
+	if bytesRead == 0 {
+		return 0, io.EOF
+	}
+	return int(bytesRead), nil
+}
+
+// Close frees resources associated with the layer reader. It will return an
+// error if there was an error while reading the layer or of the layer was not
+// completely read.
+func (r *FilterLayerReader) Close() (err error) {
+	if r.context != 0 {
+		err = exportLayerEnd(r.context)
+		if err != nil {
+			err = makeError(err, "ExportLayerEnd", "")
+		}
+		r.context = 0
+	}
+	return
+}
+
+// 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(info DriverInfo, layerID string, parentLayerPaths []string) (LayerReader, error) {
+	if procExportLayerBegin.Find() != nil {
+		// The new layer reader is not available on this Windows build. Fall back to the
+		// legacy export code path.
+		path, err := ioutil.TempDir("", "hcs")
+		if err != nil {
+			return nil, err
+		}
+		err = ExportLayer(info, layerID, path, parentLayerPaths)
+		if err != nil {
+			os.RemoveAll(path)
+			return nil, err
+		}
+		return &legacyLayerReaderWrapper{newLegacyLayerReader(path)}, nil
+	}
+
+	layers, err := layerPathsToDescriptors(parentLayerPaths)
+	if err != nil {
+		return nil, err
+	}
+	infop, err := convertDriverInfo(info)
+	if err != nil {
+		return nil, err
+	}
+	r := &FilterLayerReader{}
+	err = exportLayerBegin(&infop, layerID, layers, &r.context)
+	if err != nil {
+		return nil, makeError(err, "ExportLayerBegin", "")
+	}
+	return r, err
+}
+
+type legacyLayerReaderWrapper struct {
+	*legacyLayerReader
+}
+
+func (r *legacyLayerReaderWrapper) Close() error {
+	err := r.legacyLayerReader.Close()
+	os.RemoveAll(r.root)
+	return err
+}