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package wclayer
import (
"context"
"io/ioutil"
"os"
"path/filepath"
"strings"
"github.com/Microsoft/go-winio"
"github.com/Microsoft/hcsshim/internal/hcserror"
"github.com/Microsoft/hcsshim/internal/oc"
"github.com/Microsoft/hcsshim/internal/safefile"
"go.opencensus.io/trace"
)
// 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(ctx context.Context, path string, importFolderPath string, parentLayerPaths []string) (err error) {
title := "hcsshim::ImportLayer"
ctx, span := trace.StartSpan(ctx, title)
defer span.End()
defer func() { oc.SetSpanStatus(span, err) }()
span.AddAttributes(
trace.StringAttribute("path", path),
trace.StringAttribute("importFolderPath", importFolderPath),
trace.StringAttribute("parentLayerPaths", strings.Join(parentLayerPaths, ", ")))
// Generate layer descriptors
layers, err := layerPathsToDescriptors(ctx, parentLayerPaths)
if err != nil {
return err
}
err = importLayer(&stdDriverInfo, path, importFolderPath, layers)
if err != nil {
return hcserror.New(err, title+" - failed", "")
}
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
}
type legacyLayerWriterWrapper struct {
ctx context.Context
s *trace.Span
*legacyLayerWriter
path string
parentLayerPaths []string
}
func (r *legacyLayerWriterWrapper) Close() (err error) {
defer r.s.End()
defer func() { oc.SetSpanStatus(r.s, err) }()
defer os.RemoveAll(r.root.Name())
defer r.legacyLayerWriter.CloseRoots()
err = r.legacyLayerWriter.Close()
if err != nil {
return err
}
if err = ImportLayer(r.ctx, r.destRoot.Name(), r.path, r.parentLayerPaths); err != nil {
return err
}
for _, name := range r.Tombstones {
if err = safefile.RemoveRelative(name, r.destRoot); err != nil && !os.IsNotExist(err) {
return err
}
}
// Add any hard links that were collected.
for _, lnk := range r.PendingLinks {
if err = safefile.RemoveRelative(lnk.Path, r.destRoot); err != nil && !os.IsNotExist(err) {
return err
}
if err = safefile.LinkRelative(lnk.Target, lnk.TargetRoot, lnk.Path, r.destRoot); err != nil {
return err
}
}
// The reapplyDirectoryTimes must be called AFTER we are done with Tombstone
// deletion and hard link creation. This is because Tombstone deletion and hard link
// creation updates the directory last write timestamps so that will change the
// timestamps added by the `Add` call. Some container applications depend on the
// correctness of these timestamps and so we should change the timestamps back to
// the original value (i.e the value provided in the Add call) after this
// processing is done.
err = reapplyDirectoryTimes(r.destRoot, r.changedDi)
if err != nil {
return err
}
// Prepare the utility VM for use if one is present in the layer.
if r.HasUtilityVM {
err := safefile.EnsureNotReparsePointRelative("UtilityVM", r.destRoot)
if err != nil {
return err
}
err = ProcessUtilityVMImage(r.ctx, filepath.Join(r.destRoot.Name(), "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(ctx context.Context, path string, parentLayerPaths []string) (_ LayerWriter, err error) {
ctx, span := trace.StartSpan(ctx, "hcsshim::NewLayerWriter")
defer func() {
if err != nil {
oc.SetSpanStatus(span, err)
span.End()
}
}()
span.AddAttributes(
trace.StringAttribute("path", path),
trace.StringAttribute("parentLayerPaths", strings.Join(parentLayerPaths, ", ")))
if len(parentLayerPaths) == 0 {
// This is a base layer. It gets imported differently.
f, err := safefile.OpenRoot(path)
if err != nil {
return nil, err
}
return &baseLayerWriter{
ctx: ctx,
s: span,
root: f,
}, nil
}
importPath, err := ioutil.TempDir("", "hcs")
if err != nil {
return nil, err
}
w, err := newLegacyLayerWriter(importPath, parentLayerPaths, path)
if err != nil {
return nil, err
}
return &legacyLayerWriterWrapper{
ctx: ctx,
s: span,
legacyLayerWriter: w,
path: importPath,
parentLayerPaths: parentLayerPaths,
}, nil
}
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