motiejus/undocker
1
Fork 0
Code Packages Releases Activity

doc

Browse Source
This commit is contained in:
Motiejus Jakštys
2021-05-24 00:11:58 +03:00
parent ce8ce9f59e
commit 4c7afb8afa
5 changed files with 249 additions and 90 deletions
Download Patch File Download Diff File Expand all files Collapse all files

176
rootfs/rootfs_test.go
View File

@@ -14,11 +14,11 @@ import (
func TestRootFS(t *testing.T) {
layer0 := tarball{
dir{name: "/", uid: 0},
file{name: "/file", uid: 0, contents: []byte("from 0")},
file{name: "/file", uid: 0, contents: bytes.NewBufferString("from 0")},
}
layer1 := tarball{
file{name: "/file", uid: 1, contents: []byte("from 1")},
file{name: "/file", uid: 1, contents: bytes.NewBufferString("from 1")},
}
layer2 := tarball{
@@ -44,34 +44,95 @@ func TestRootFS(t *testing.T) {
{
name: "basic file overwrite, layer order mixed",
image: tarball{
file{name: "layer1/layer.tar", contents: layer1.bytes(t)},
file{name: "layer0/layer.tar", contents: layer0.bytes(t)},
file{name: "layer1/layer.tar", contents: layer1},
file{name: "layer0/layer.tar", contents: layer0},
manifest{"layer0/layer.tar", "layer1/layer.tar"},
},
want: []extractable{
dir{name: "/", uid: 0},
file{name: "/file", uid: 1, contents: []byte("from 1")},
file{name: "/file", uid: 1, contents: bytes.NewBufferString("from 1")},
},
},
{
name: "directory overwrite retains original dir",
image: tarball{
file{name: "layer2/layer.tar", contents: layer2.bytes(t)},
file{name: "layer0/layer.tar", contents: layer0.bytes(t)},
file{name: "layer1/layer.tar", contents: layer1.bytes(t)},
file{name: "layer2/layer.tar", contents: layer2},
file{name: "layer0/layer.tar", contents: layer0},
file{name: "layer1/layer.tar", contents: layer1},
manifest{"layer0/layer.tar", "layer1/layer.tar", "layer2/layer.tar"},
},
want: []extractable{
dir{name: "/", uid: 0},
file{name: "/file", uid: 1, contents: []byte("from 1")},
file{name: "/file", uid: 1, contents: bytes.NewBufferString("from 1")},
dir{name: "/", uid: 2},
},
},
{
name: "simple whiteout",
image: tarball{
file{name: "layer0/layer.tar", contents: tarball{
file{name: "filea"},
file{name: "fileb"},
dir{name: "dira"},
dir{name: "dirb"},
}},
file{name: "layer1/layer.tar", contents: tarball{
hardlink{name: ".wh.filea"},
hardlink{name: ".wh.dira"},
}},
manifest{"layer0/layer.tar", "layer1/layer.tar"},
},
want: []extractable{
file{name: "fileb"},
dir{name: "dirb"},
},
},
{
name: "whiteout with override",
image: tarball{
file{name: "layer0/layer.tar", contents: tarball{
file{name: "filea", contents: bytes.NewBufferString("from 0")},
}},
file{name: "layer1/layer.tar", contents: tarball{
hardlink{name: ".wh.filea"},
}},
file{name: "layer2/layer.tar", contents: tarball{
file{name: "filea", contents: bytes.NewBufferString("from 3")},
}},
manifest{
"layer0/layer.tar",
"layer1/layer.tar",
"layer2/layer.tar",
},
},
want: []extractable{
file{name: "filea", contents: bytes.NewBufferString("from 3")},
},
},
{
name: "files and directories do not whiteout",
image: tarball{
file{name: "layer0/layer.tar", contents: tarball{
dir{name: "dir"},
file{name: "file"},
}},
file{name: "layer1/layer.tar", contents: tarball{
dir{name: ".wh.dir"},
file{name: ".wh.file"},
}},
},
want: []extractable{
dir{name: "dir"},
dir{name: ".wh.dir"},
file{name: "file"},
file{name: ".wh.file"},
},
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
in := bytes.NewReader(tt.image.bytes(t))
in := bytes.NewReader(tt.image.Bytes())
out := bytes.Buffer{}
err := RootFS(in, &out)
@@ -81,15 +142,31 @@ func TestRootFS(t *testing.T) {
}
require.NoError(t, err)
got := extract(t, &out)
assert.Equal(t, got, tt.want)
assert.Equal(t, tt.want, got)
})
}
}
// Helpers
type tarrable interface {
tar(*testing.T, *tar.Writer)
type tarrer interface {
tar(*tar.Writer)
}
type byter interface {
Bytes() []byte
}
type tarball []tarrer
func (tb tarball) Bytes() []byte {
buf := bytes.Buffer{}
tw := tar.NewWriter(&buf)
for _, member := range tb {
member.tar(tw)
}
tw.Close()
return buf.Bytes()
}
// extractable is an empty interface for comparing extracted outputs in tests.
@@ -101,63 +178,70 @@ type dir struct {
uid int
}
func (d dir) tar(t *testing.T, tw *tar.Writer) {
t.Helper()
func (d dir) tar(tw *tar.Writer) {
hdr := &tar.Header{
Typeflag: tar.TypeDir,
Name: d.name,
Mode: 0644,
Uid: d.uid,
}
require.NoError(t, tw.WriteHeader(hdr))
tw.WriteHeader(hdr)
}
type file struct {
name string
uid int
contents []byte
contents byter
}
func (f file) tar(t *testing.T, tw *tar.Writer) {
t.Helper()
func (f file) tar(tw *tar.Writer) {
var contentbytes []byte
if f.contents != nil {
contentbytes = f.contents.Bytes()
}
hdr := &tar.Header{
Typeflag: tar.TypeReg,
Name: f.name,
Mode: 0644,
Uid: f.uid,
Size: int64(len(f.contents)),
Size: int64(len(contentbytes)),
}
require.NoError(t, tw.WriteHeader(hdr))
_, err := tw.Write(f.contents)
require.NoError(t, err)
tw.WriteHeader(hdr)
tw.Write(contentbytes)
}
type manifest []string
func (m manifest) tar(t *testing.T, tw *tar.Writer) {
t.Helper()
func (m manifest) tar(tw *tar.Writer) {
b, err := json.Marshal(dockerManifestJSON{{Layers: m}})
require.NoError(t, err)
file{name: "manifest.json", uid: 0, contents: b}.tar(t, tw)
}
type tarball []tarrable
func (tb tarball) bytes(t *testing.T) []byte {
t.Helper()
buf := bytes.Buffer{}
tw := tar.NewWriter(&buf)
for _, member := range tb {
member.tar(t, tw)
if err != nil {
panic("testerr")
}
require.NoError(t, tw.Close())
return buf.Bytes()
file{
name: "manifest.json",
uid: 0,
contents: bytes.NewBuffer(b),
}.tar(tw)
}
func extract(t *testing.T, f io.Reader) []extractable {
type hardlink struct {
name string
uid int
}
func (h hardlink) tar(tw *tar.Writer) {
tw.WriteHeader(&tar.Header{
Typeflag: tar.TypeLink,
Name: h.name,
Mode: 0644,
Uid: h.uid,
})
}
func extract(t *testing.T, r io.Reader) []extractable {
t.Helper()
ret := []extractable{}
tr := tar.NewReader(f)
tr := tar.NewReader(r)
for {
hdr, err := tr.Next()
if err == io.EOF {
@@ -170,9 +254,13 @@ func extract(t *testing.T, f io.Reader) []extractable {
case tar.TypeDir:
elem = dir{name: hdr.Name, uid: hdr.Uid}
case tar.TypeReg:
buf := bytes.Buffer{}
io.Copy(&buf, tr)
elem = file{name: hdr.Name, uid: hdr.Uid, contents: buf.Bytes()}
f := file{name: hdr.Name, uid: hdr.Uid}
if hdr.Size > 0 {
var buf bytes.Buffer
io.Copy(&buf, tr)
f.contents = &buf
}
elem = f
}
ret = append(ret, elem)
}