Golang hcsshim.NewLayerReader函數代碼示例

// Changes produces a list of changes between the specified layer
// and its parent layer. If parent is "", then all changes will be ADD changes.
// The layer should be mounted when calling this function
func (d *Driver) Changes(id, parent string) ([]archive.Change, error) {
	rID, err := d.resolveID(id)
	if err != nil {
		return nil, err
	}
	parentChain, err := d.getLayerChain(rID)
	if err != nil {
		return nil, err
	}

	// this is assuming that the layer is unmounted
	if err := hcsshim.UnprepareLayer(d.info, rID); err != nil {
		return nil, err
	}
	defer func() {
		if err := hcsshim.PrepareLayer(d.info, rID, parentChain); err != nil {
			logrus.Warnf("Failed to Deactivate %s: %s", rID, err)
		}
	}()

	var changes []archive.Change
	err = winio.RunWithPrivilege(winio.SeBackupPrivilege, func() error {
		r, err := hcsshim.NewLayerReader(d.info, id, parentChain)
		if err != nil {
			return err
		}
		defer r.Close()

		for {
			name, _, fileInfo, err := r.Next()
			if err == io.EOF {
				return nil
			}
			if err != nil {
				return err
			}
			name = filepath.ToSlash(name)
			if fileInfo == nil {
				changes = append(changes, archive.Change{Path: name, Kind: archive.ChangeDelete})
			} else {
				// Currently there is no way to tell between an add and a modify.
				changes = append(changes, archive.Change{Path: name, Kind: archive.ChangeModify})
			}
		}
	})
	if err != nil {
		return nil, err
	}

	return changes, nil
}

// exportLayer generates an archive from a layer based on the given ID.
func (d *Driver) exportLayer(id string, parentLayerPaths []string) (archive.Archive, error) {
	if hcsshim.IsTP4() {
		// Export in TP4 format to maintain compatibility with existing images and
		// because ExportLayer is somewhat broken on TP4 and can't work with the new
		// scheme.
		tempFolder, err := ioutil.TempDir("", "hcs")
		if err != nil {
			return nil, err
		}
		defer func() {
			if err != nil {
				os.RemoveAll(tempFolder)
			}
		}()

		if err = hcsshim.ExportLayer(d.info, id, tempFolder, parentLayerPaths); err != nil {
			return nil, err
		}
		archive, err := archive.Tar(tempFolder, archive.Uncompressed)
		if err != nil {
			return nil, err
		}
		return ioutils.NewReadCloserWrapper(archive, func() error {
			err := archive.Close()
			os.RemoveAll(tempFolder)
			return err
		}), nil
	}

	var r hcsshim.LayerReader
	r, err := hcsshim.NewLayerReader(d.info, id, parentLayerPaths)
	if err != nil {
		return nil, err
	}

	archive, w := io.Pipe()
	go func() {
		err := writeTarFromLayer(r, w)
		cerr := r.Close()
		if err == nil {
			err = cerr
		}
		w.CloseWithError(err)
	}()

	return archive, nil
}

// exportLayer generates an archive from a layer based on the given ID.
func (d *Driver) exportLayer(id string, parentLayerPaths []string) (archive.Archive, error) {
	var r hcsshim.LayerReader
	r, err := hcsshim.NewLayerReader(d.info, id, parentLayerPaths)
	if err != nil {
		return nil, err
	}

	archive, w := io.Pipe()
	go func() {
		err := writeTarFromLayer(r, w)
		cerr := r.Close()
		if err == nil {
			err = cerr
		}
		w.CloseWithError(err)
	}()

	return archive, nil
}

// exportLayer generates an archive from a layer based on the given ID.
func (d *Driver) exportLayer(id string, parentLayerPaths []string) (archive.Archive, error) {
	archive, w := io.Pipe()
	go func() {
		err := winio.RunWithPrivilege(winio.SeBackupPrivilege, func() error {
			r, err := hcsshim.NewLayerReader(d.info, id, parentLayerPaths)
			if err != nil {
				return err
			}

			err = writeTarFromLayer(r, w)
			cerr := r.Close()
			if err == nil {
				err = cerr
			}
			return err
		})
		w.CloseWithError(err)
	}()

	return archive, nil
}

// Changes produces a list of changes between the specified layer
// and its parent layer. If parent is "", then all changes will be ADD changes.
func (d *Driver) Changes(id, parent string) ([]archive.Change, error) {
	rID, err := d.resolveID(id)
	if err != nil {
		return nil, err
	}
	parentChain, err := d.getLayerChain(rID)
	if err != nil {
		return nil, err
	}

	d.Lock()
	if d.info.Flavour == filterDriver {
		if d.active[rID] == 0 {
			if err = hcsshim.ActivateLayer(d.info, rID); err != nil {
				d.Unlock()
				return nil, err
			}
			defer func() {
				if err := hcsshim.DeactivateLayer(d.info, rID); err != nil {
					logrus.Warnf("Failed to Deactivate %s: %s", rID, err)
				}
			}()
		} else {
			if err = hcsshim.UnprepareLayer(d.info, rID); err != nil {
				d.Unlock()
				return nil, err
			}
			defer func() {
				if err := hcsshim.PrepareLayer(d.info, rID, parentChain); err != nil {
					logrus.Warnf("Failed to re-PrepareLayer %s: %s", rID, err)
				}
			}()
		}
	}
	d.Unlock()

	r, err := hcsshim.NewLayerReader(d.info, id, parentChain)
	if err != nil {
		return nil, err
	}
	defer r.Close()

	var changes []archive.Change
	for {
		name, _, fileInfo, err := r.Next()
		if err == io.EOF {
			break
		}
		if err != nil {
			return nil, err
		}
		name = filepath.ToSlash(name)
		if fileInfo == nil {
			changes = append(changes, archive.Change{name, archive.ChangeDelete})
		} else {
			// Currently there is no way to tell between an add and a modify.
			changes = append(changes, archive.Change{name, archive.ChangeModify})
		}
	}
	return changes, nil
}