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package hcsshim
import (
"errors"
"io/ioutil"
"os"
"path/filepath"
"github.com/Microsoft/go-winio"
"github.com/sirupsen/logrus"
)
// ImportLayer will take the contents of the folder at importFolderPath and import
// that into a layer with the id layerId. Note that in order to correctly populate
// the layer and interperet the transport format, all parent layers must already
// be present on the system at the paths provided in parentLayerPaths.
func ImportLayer(info DriverInfo, layerID string, importFolderPath string, parentLayerPaths []string) error {
title := "hcsshim::ImportLayer "
logrus.Debugf(title+"flavour %d layerId %s folder %s", info.Flavour, layerID, importFolderPath)
// 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 = importLayer(&infop, layerID, importFolderPath, layers)
if err != nil {
err = makeErrorf(err, title, "layerId=%s flavour=%d folder=%s", layerID, info.Flavour, importFolderPath)
logrus.Error(err)
return err
}
logrus.Debugf(title+"succeeded flavour=%d layerId=%s folder=%s", info.Flavour, layerID, importFolderPath)
return nil
}
// LayerWriter is an interface that supports writing a new container image layer.
type LayerWriter interface {
// Add adds a file to the layer with given metadata.
Add(name string, fileInfo *winio.FileBasicInfo) error
// AddLink adds a hard link to the layer. The target must already have been added.
AddLink(name string, target string) error
// Remove removes a file that was present in a parent layer from the layer.
Remove(name string) error
// Write writes data to the current file. The data must be in the format of a Win32
// backup stream.
Write(b []byte) (int, error)
// Close finishes the layer writing process and releases any resources.
Close() error
}
// FilterLayerWriter provides an interface to write the contents of a layer to the file system.
type FilterLayerWriter struct {
context uintptr
}
// Add adds a file or directory to the layer. The file's parent directory must have already been added.
//
// name contains the file's relative path. fileInfo contains file times and file attributes; the rest
// of the file metadata and the file data must be written as a Win32 backup stream to the Write() method.
// winio.BackupStreamWriter can be used to facilitate this.
func (w *FilterLayerWriter) Add(name string, fileInfo *winio.FileBasicInfo) error {
if name[0] != '\\' {
name = `\` + name
}
err := importLayerNext(w.context, name, fileInfo)
if err != nil {
return makeError(err, "ImportLayerNext", "")
}
return nil
}
// AddLink adds a hard link to the layer. The target of the link must have already been added.
func (w *FilterLayerWriter) AddLink(name string, target string) error {
return errors.New("hard links not yet supported")
}
// Remove removes a file from the layer. The file must have been present in the parent layer.
//
// name contains the file's relative path.
func (w *FilterLayerWriter) Remove(name string) error {
if name[0] != '\\' {
name = `\` + name
}
err := importLayerNext(w.context, name, nil)
if err != nil {
return makeError(err, "ImportLayerNext", "")
}
return nil
}
// Write writes more backup stream data to the current file.
func (w *FilterLayerWriter) Write(b []byte) (int, error) {
err := importLayerWrite(w.context, b)
if err != nil {
err = makeError(err, "ImportLayerWrite", "")
return 0, err
}
return len(b), err
}
// Close completes the layer write operation. The error must be checked to ensure that the
// operation was successful.
func (w *FilterLayerWriter) Close() (err error) {
if w.context != 0 {
err = importLayerEnd(w.context)
if err != nil {
err = makeError(err, "ImportLayerEnd", "")
}
w.context = 0
}
return
}
type legacyLayerWriterWrapper struct {
*legacyLayerWriter
info DriverInfo
layerID string
path string
parentLayerPaths []string
}
func (r *legacyLayerWriterWrapper) Close() error {
defer os.RemoveAll(r.root)
err := r.legacyLayerWriter.Close()
if err != nil {
return err
}
// Use the original path here because ImportLayer does not support long paths for the source in TP5.
// But do use a long path for the destination to work around another bug with directories
// with MAX_PATH - 12 < length < MAX_PATH.
info := r.info
fullPath, err := makeLongAbsPath(filepath.Join(info.HomeDir, r.layerID))
if err != nil {
return err
}
info.HomeDir = ""
if err = ImportLayer(info, fullPath, r.path, r.parentLayerPaths); err != nil {
return err
}
// Add any hard links that were collected.
for _, lnk := range r.PendingLinks {
if err = os.Remove(lnk.Path); err != nil && !os.IsNotExist(err) {
return err
}
if err = os.Link(lnk.Target, lnk.Path); err != nil {
return err
}
}
// Prepare the utility VM for use if one is present in the layer.
if r.HasUtilityVM {
err = ProcessUtilityVMImage(filepath.Join(fullPath, "UtilityVM"))
if err != nil {
return err
}
}
return nil
}
// NewLayerWriter returns a new layer writer for creating a layer on disk.
// The caller must have taken the SeBackupPrivilege and SeRestorePrivilege privileges
// to call this and any methods on the resulting LayerWriter.
func NewLayerWriter(info DriverInfo, layerID string, parentLayerPaths []string) (LayerWriter, error) {
if len(parentLayerPaths) == 0 {
// This is a base layer. It gets imported differently.
return &baseLayerWriter{
root: filepath.Join(info.HomeDir, layerID),
}, nil
}
if procImportLayerBegin.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
}
return &legacyLayerWriterWrapper{
legacyLayerWriter: newLegacyLayerWriter(path, parentLayerPaths, filepath.Join(info.HomeDir, layerID)),
info: info,
layerID: layerID,
path: path,
parentLayerPaths: parentLayerPaths,
}, nil
}
layers, err := layerPathsToDescriptors(parentLayerPaths)
if err != nil {
return nil, err
}
infop, err := convertDriverInfo(info)
if err != nil {
return nil, err
}
w := &FilterLayerWriter{}
err = importLayerBegin(&infop, layerID, layers, &w.context)
if err != nil {
return nil, makeError(err, "ImportLayerStart", "")
}
return w, nil
}
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