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archive: Expose ChangeWriter to allow customized diff computing

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Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>
This commit is contained in:
ktock 2021-06-17 15:25:40 +09:00
parent ba70277fb7
commit 4a46ea2f4b
2 changed files with 25 additions and 8 deletions
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31
archive/tar.go
View File

@ -91,7 +91,7 @@ func WriteDiff(ctx context.Context, w io.Writer, a, b string, opts ...WriteDiffO
// based off AUFS whiteouts.
// See https://github.com/opencontainers/image-spec/blob/master/layer.md
func writeDiffNaive(ctx context.Context, w io.Writer, a, b string, _ WriteDiffOptions) error {
cw := newChangeWriter(w, b)
cw := NewChangeWriter(w, b)
err := fs.Changes(ctx, a, b, cw.HandleChange)
if err != nil {
return errors.Wrap(err, "failed to create diff tar stream")
@ -462,7 +462,17 @@ func mkparent(ctx context.Context, path, root string, parents []string) error {
return nil
}
type changeWriter struct {
// ChangeWriter provides tar stream from filesystem change information.
// The privided tar stream is styled as an OCI layer. Change information
// (add/modify/delete/unmodified) for each file needs to be passed to this
// writer through HandleChange method.
//
// This should be used combining with continuity's diff computing functionality
// (e.g. `fs.Change` of github.com/containerd/continuity/fs).
//
// See also https://github.com/opencontainers/image-spec/blob/master/layer.md for details
// about OCI layers
type ChangeWriter struct {
tw *tar.Writer
source string
whiteoutT time.Time
@ -471,8 +481,11 @@ type changeWriter struct {
addedDirs map[string]struct{}
}
func newChangeWriter(w io.Writer, source string) *changeWriter {
return &changeWriter{
// NewChangeWriter returns ChangeWriter that writes tar stream of the source directory
// to the privided writer. Change information (add/modify/delete/unmodified) for each
// file needs to be passed through HandleChange method.
func NewChangeWriter(w io.Writer, source string) *ChangeWriter {
return &ChangeWriter{
tw: tar.NewWriter(w),
source: source,
whiteoutT: time.Now(),
@ -482,7 +495,10 @@ func newChangeWriter(w io.Writer, source string) *changeWriter {
}
}
func (cw *changeWriter) HandleChange(k fs.ChangeKind, p string, f os.FileInfo, err error) error {
// HandleChange receives filesystem change information and reflect that information to
// the result tar stream. This function implements `fs.ChangeFunc` of continuity
// (github.com/containerd/continuity/fs) and should be used with that package.
func (cw *ChangeWriter) HandleChange(k fs.ChangeKind, p string, f os.FileInfo, err error) error {
if err != nil {
return err
}
@ -630,14 +646,15 @@ func (cw *changeWriter) HandleChange(k fs.ChangeKind, p string, f os.FileInfo, e
return nil
}
func (cw *changeWriter) Close() error {
// Close closes this writer.
func (cw *ChangeWriter) Close() error {
if err := cw.tw.Close(); err != nil {
return errors.Wrap(err, "failed to close tar writer")
}
return nil
}
func (cw *changeWriter) includeParents(hdr *tar.Header) error {
func (cw *ChangeWriter) includeParents(hdr *tar.Header) error {
if cw.addedDirs == nil {
return nil
}

2
archive/tar_linux_test.go
View File

@ -71,7 +71,7 @@ func TestOverlayApplyNoParents(t *testing.T) {
fstest.FSSuite(t, overlayDiffApplier{
tmp: base,
diff: func(ctx context.Context, w io.Writer, a, b string, _ ...WriteDiffOpt) error {
cw := newChangeWriter(w, b)
cw := NewChangeWriter(w, b)
cw.addedDirs = nil
err := fs.Changes(ctx, a, b, cw.HandleChange)
if err != nil {