motiejus/undocker
1
Fork 0
Code Packages Releases Activity

simplify flattener api

Browse Source
This commit is contained in:
Motiejus Jakštys
2021-05-24 00:11:58 +03:00
parent e2cf760c12
commit 9ca0d8019c
5 changed files with 18 additions and 38 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
rootfs/rootfs.go
View File

@@ -27,11 +27,6 @@ var (
)
type (
// RootFS accepts a docker layer tarball and flattens it.
RootFS struct {
rd io.ReadSeeker
}
dockerManifestJSON []struct {
Layers []string `json:"Layers"`
}
@@ -42,14 +37,11 @@ type (
}
)
// New creates a new RootFS'er.
func New(rd io.ReadSeeker) *RootFS {
return &RootFS{rd: rd}
}
// Flatten flattens a docker image to an open tarball.
func (r *RootFS) Flatten(w io.Writer) (err error) {
tr := tar.NewReader(r.rd)
// Flatten flattens a docker image to a tarball. The underlying io.Writer
// should be an open file handle, which the caller is responsible for closing
// themselves
func Flatten(rd io.ReadSeeker, w io.Writer) (err error) {
tr := tar.NewReader(rd)
var closer func() error
// layerOffsets maps a layer name (a9b123c0daa/layer.tar) to it's offset
@@ -74,7 +66,7 @@ func (r *RootFS) Flatten(w io.Writer) (err error) {
return fmt.Errorf("decode %s: %w", _manifestJSON, err)
}
case strings.HasSuffix(hdr.Name, _layerSuffix):
here, err := r.rd.Seek(0, io.SeekCurrent)
here, err := rd.Seek(0, io.SeekCurrent)
if err != nil {
return err
}
@@ -107,10 +99,10 @@ func (r *RootFS) Flatten(w io.Writer) (err error) {
// iterate over all files, construct `file2layer`, `whreaddir`, `wh`
for i, no := range layers {
if _, err := r.rd.Seek(no.offset, io.SeekStart); err != nil {
if _, err := rd.Seek(no.offset, io.SeekStart); err != nil {
return err
}
tr, closer = openTargz(r.rd)
tr, closer = openTargz(rd)
for {
hdr, err := tr.Next()
if err == io.EOF {
@@ -154,10 +146,10 @@ func (r *RootFS) Flatten(w io.Writer) (err error) {
}()
// iterate through all layers, all files, and write files.
for i, no := range layers {
if _, err := r.rd.Seek(no.offset, io.SeekStart); err != nil {
if _, err := rd.Seek(no.offset, io.SeekStart); err != nil {
return err
}
tr, closer = openTargz(r.rd)
tr, closer = openTargz(rd)
for {
hdr, err := tr.Next()
if err == io.EOF {

2
rootfs/rootfs_test.go
View File

@@ -186,7 +186,7 @@ func TestRootFS(t *testing.T) {
in := bytes.NewReader(tt.image.Buffer().Bytes())
out := bytes.Buffer{}
err := New(in).Flatten(&out)
err := Flatten(in, &out)
if tt.wantErr != "" {
assert.EqualError(t, err, tt.wantErr)
return